Introduction
In cow–calf herds, calf morbidity and mortality affect productivity by increasing treatment costs, reducing weaning weights, and limiting the number of available calves for sale at weaning (Ganaba et al., Reference Ganaba, Bigras-Poulin, Bélanger and Couture1995). In western Canada, the average herd-level treatment risk of preweaning disease is estimated at 9.4% (Pearson et al., Reference Pearson, Pajor, Caulkett, Levy, Campbell and Windeyer2019a). The leading causes of treatment are neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) (Ganaba et al., Reference Ganaba, Bigras-Poulin, Bélanger and Couture1995; Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016; Pearson et al., Reference Pearson, Pajor, Caulkett, Levy, Campbell and Windeyer2019a; Waldner et al., Reference Waldner, Jelinski and McIntyre-Zimmer2013). Furthermore, sick calves have increased mortality risk compared to healthy ones (Busato et al., Reference Busato, Steiner, Martin, Shoukri and Gaillard1997; Ganaba et al., Reference Ganaba, Bigras-Poulin, Bélanger and Couture1995; Mõtus et al., Reference Mõtus, Viltrop and Emanuelson2018). Thus, preventing NCD and BRD in preweaned beef calves is critical.
Neonatal calf diarrhea is a multifactorial infectious syndrome that affects the gastrointestinal tract of calves (Acres et al., Reference Acres, Saunders and Radostits1977; Cho and Yoon, Reference Cho and Yoon2014; Muktar et al., Reference Muktar, Mamo, Tesfaye and Belina2015). In beef calves, clinical cases usually occur during the first month of life (Clement et al., Reference Clement, King, Salman, Wittum, Casper and Odde1995; Smith et al., Reference Smith, Grotelueschen, Knott, Clowser and Nason2008), although the onset of clinical signs varies depending on the agents involved (Cho and Yoon, Reference Cho and Yoon2014). Escherichia coli (E. coli) (Acres et al., Reference Acres, Saunders and Radostits1977; Myers, Reference Myers1976), bovine rotavirus (BRoV) (Cornaglia et al., Reference Cornaglia, Fernández, Gottschalk, Barrandeguy, Luchelli, Pasini, Saif, Parraud, Romat and Schudel1992), bovine coronavirus (BCoV) (Torres-Medina et al., Reference Torres-Medina, Schlafer and Mebus1985), and Cryptosporidium parvum (Thomson et al., Reference Thomson, Hamilton, Hope, Katzer, Mabbott, Morrison and Innes2017) are frequently the causative agents of NCD, alone or in combination. Case definitions usually focus on reduced fecal consistency (Myers, Reference Myers1976), weakness, anorexia, and dehydration (Acres et al., Reference Acres, Saunders and Radostits1977; Wilson et al., Reference Wilson, Habing, Winder and Renaud2023). In western Canada, on average 3–5.5% of calves are treated for NCD (Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016; Pearson et al., Reference Pearson, Pajor, Caulkett, Levy, Campbell and Windeyer2019a; Waldner et al., Reference Waldner, Jelinski and McIntyre-Zimmer2013), but the range of affected calves may vary widely across herds (Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022). Minimizing the impact of NCD could optimize calf health and increase economic revenue for producers.
Bovine respiratory disease is a multifactorial respiratory syndrome (Taylor et al., Reference Taylor, Fulton, Lehenbauer, Step and Confer2010). During the preweaning period, it typically affects calves from 3 weeks of age until weaning (United States Department of Agriculture Animal and Plant Health Inspection Service Veterinary Services National Animal Health Monitoring System, 1997). Clinical disease is triggered by a combined effect of viruses and bacteria (Cuasck et al., Reference Cusack, Mc Meniman and Lean2003), and the disease risk is often enhanced by stress-related factors that cause immunosuppression or sudden changes in environmental conditions (Taylor et al., Reference Taylor, Fulton, Lehenbauer, Step and Confer2010). Typical pathogens involved include Mannheimia haemolytica (M. haemolytica), Pasteurella multocida, Histophilus somni, Mycoplasma bovis, bovine herpesvirus type 1 (BHV1), bovine respiratory syncytial virus (BRSV), parainfluenza virus type 3 (PIV3), BCoV, and bovine viral diarrhoea virus (BVDV) (Campbell, Reference Campbell2022). Early clinical signs involve depression, loss of appetite, and body temperature above 104°F. More advanced cases may present with difficulty breathing, coughing, and nasal discharge (Kasimanickam, Reference Kasimanickam2010). In western Canada, the average herd-level treatment risk for BRD during the preweaning stage has been estimated between 2.7% and 3.8% (Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016; Waldner et al., Reference Waldner, Jelinski and McIntyre-Zimmer2013). However, its impact also varies across herds (Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022) and between years (Muggli-Cockett et al., Reference Muggli-Cockett, Cundiff and Gregory1992). Therefore, preventing BRD in cow–calf herds is also essential to ensuring good calf health and economic returns to producers.
Given the detrimental effects of NCD and BRD on calf health, disease control strategies are a cornerstone for optimizing the production of calves and ensuring economic returns. Prevention is more beneficial than treatment of affected animals (Thrusfield and Christley, Reference Thrusfield and Christley2018). For instance, the per annum cost of prevention of BRD in beef cow–calf herds in the United States was estimated at $13.74 USD per calf compared to $32.45 USD for treatment (Wang et al., Reference Wang, Schneider, Hubbard, Grotelueschen, Daly, Stokka and Smith2018). While identifying practices that should be recommended to control disease in farms is essential to boost cow–calf productivity, there is still a knowledge gap concerning which are these are currently most effective, and this information has not been compiled before. This leads to the question: What is the effectiveness of management practices to prevent beef calf morbidity and mortality caused by NCD and BRD during the preweaning stage?
The objective of this systematic review was to assess and summarize the evidence on the effectiveness of management practices to prevent calf morbidity and mortality from NCD and BRD on beef cow–calf herds. A secondary objective was to assess the generalizability of this evidence to cow–calf operations in western Canada.
Materials and methods
The methods used for this systematic review were described previously (Sanguinetti et al., Reference Sanguinetti, Strong, Agbese, Adams, Campbell, Checkley, de Jong, Ganshorn and Windeyer2021, Reference Santinello, Diana, De Marchi, Scali, Bertocchi, Lorenzi, Alborali and Penasa2025) and will be described briefly here. This study followed the preferred reporting items for systematic reviews and meta-analyses reporting guideline (PRISMA 2020) (Page et al., Reference Page, McKenzie, Bossuyt, Boutron, Hoffmann, Mulrow, Shamseer, Tetzlaff, Akl, Brennan, Chou, Glanville, Grimshaw, Hróbjartsson, Lalu, Li, Loder, Mayo-Wilson, McDonald, McGuinness, Stewart, Thomas, Tricco, Welch, Whiting and Moher2021) and a series of articles for conducting systematic reviews in veterinary medicine (O’Connor et al., Reference O’Connor, Anderson, Goodell and Sargeant2014; O’Connor and Sargeant, Reference O’Connor and Sargeant2014; Sargeant et al., Reference Sargeant, Kelton and O’Connor2014a, Reference Sargeant, Kelton and O’Connor2014b; Sargeant and O’Connor, Reference Sargeant and O’Connor2014).
Protocol and registration
Before starting the review, a protocol was developed following the PRISMA-P guidelines (Moher et al., Reference Moher, Shamseer, Clarke, Ghersi, Liberati, Petticrew, Shekelle, Stewart and Group2015) and published in the Digital Repository of the University of Calgary (https://prism.ucalgary.ca) and online with Systematic Reviews for Animals and Food (http://www.syreaf.org/) (Sanguinetti et al., Reference Sanguinetti, Adams, Campbell, Checkley and Windeyer2021).
Eligibility criteria
Population
The population of interest was preweaned beef calves.
Interventions and comparators
The interventions of interest were practices related to colostrum management, breeding and calving, nutritional management, biosecurity, and vaccination used in calves or pregnant dams. Studies were required to have a concurrent comparison group (i.e., placebo or alternate practice).
Outcomes
The outcomes of interest were treatment for, or morbidity or mortality from NCD and BRD.
Study designs and report characteristics
Eligible study designs were randomized controlled trials (RCTs), controlled trials (CTs), and observational studies that statistically assessed the relationship between an intervention (i.e., practice) and an outcome of interest. Only studies reporting naturally occurring diseases and written in English were included.
Information sources and search strategy
Electronic databases used for the literature search included CAB Abstracts, MEDLINE on the Ovid platform, Web of Science, and ProQuest Dissertations. The first search was carried out on 20/5/2021 and updated on 5/4/2023 to incorporate recent publications. Covidence (Veritas Health Innovation, Melbourne, Australia) was used to import, de-duplicate, and classify studies.
Screening and selection process
Two independent reviewers assessed the relevancy of studies in two stages. The first stage involved title and abstract screening, and the second involved full-text review. Details concerning signalling questions and conflict resolution are shown in the protocol and in the related manuscript (Sanguinetti et al., Reference Sanguinetti, Strong, Agbese, Adams, Campbell, Checkley, de Jong, Ganshorn and Windeyer2021, Reference Santinello, Diana, De Marchi, Scali, Bertocchi, Lorenzi, Alborali and Penasa2025).
Data collection process
Data were extracted by two reviewers using Microsoft Excel (Microsoft Corporation, Redmond, WA). During this stage, studies were anonymized by using a numeric code (Table 1). Study-level information and individual practice assessments (PAs) were isolated and extracted from each study. The term PA refers to the statistical assessment between a practice and an outcome of interest. Each PA was identified using an alphanumeric code in accordance with the numeric code given to each study (Tables 4–9; Supplementary material 1). Associations or effects were considered statistically significant if P ≤ 0.05. The terms statistically significant associations (A) or no statistically significant associations (NA) were used to describe the findings of PAs from observational studies. The terms statistically significant effects (E) or no statistically significant effects (NE) were used to describe the findings of PAs from RCTs and CTs. Preference was given to extracting univariable analyses over multivariable ones if both were reported because of concerns about a lack of independence among practices. If possible, estimates were extracted from tables, focusing on the directionality of findings (i.e., protective or harmful) instead of the specific estimate.
Characteristics of studies included in a systematic review on the effect of management practices on pre-weaned calf morbidity and mortality from neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) in beef cow–calf herds
RCT, randomized controlled trial; CT, controlled trial; Y–Se, organic selenium; Na–Se, sodium selenite; BRSV, bovine respiratory syncytial virus; PI3, parainfluenza virus type 3.
a Estimates calculated by the reviewers from published results (Cohen et al., Reference Cohen, King, Guenther and Janzen1991; Myers et al., Reference Myers1980)
Risk of bias
The methods used to evaluate the risk of bias were based on the Rob2 tool (Sterne et al., Reference Sterne, Savović, Page, Elbers, Blencowe, Boutron, Cates, Cheng, Corbett, Eldridge, Emberson, Hernán, Hopewell, Hróbjartsson, Junqueira, Jüni, Kirkham, Lasserson, Li, McAleenan, Reeves, Shepperd, Shrier, Stewart, Tilling, White, Whiting and Higgins2019) and ROBINS I tool (Sterne et al., Reference Sterne, Hernán, Reeves, Savović, Berkman, Viswanathan, Henry, Altman, Ansari, Boutron, Carpenter, Chan, Churchill, Deeks, Hróbjartsson, Kirkham, Jüni, Loke, Pigott, Ramsay, Regidor, Rothstein, Sandhu, Santaguida, Schünemann, Shea, Shrier, Tugwell, Turner, Valentine, Waddington, Waters, Wells, Whiting and Higgins2016). Two reviewers conducted this assessment. Modifications were made to make them relevant to veterinary medicine (Sargeant and O’Connor, Reference Sargeant and O’Connor2014).
Data synthesis
The evidence concerning calf morbidity and mortality from NCD and BRD was summarized using a narrative structure, organized by practices with evidence showing statistically significant associations or effects then practices without statistically significant associations or effects. A summary of findings table was created for all PAs. If the body of evidence for a specific practice had more than three PAs from different studies assessing the same outcomes, the certainty of the body of evidence was assessed using the GRADE approach (Schünemann et al., Reference Schünemann, Brożek, Guyatt and Oxman2013). This assessment considered consistency in the directionality of findings across PAs (i.e., protective or harmful). Bodies of evidence whose PAs had at least 60–70% of their findings indicating the same direction were considered to have a consistent directionality of findings, those with 40–59% were considered semi-consistent, and those with less than 40% of findings indicating the same direction were considered inconsistent. Also, the GRADE approach assessed how comparable the practices and comparison groups were across PAs and how comparable the productiion conditions in the PAs were relative to those on western Canadian cow–calf operations.
Results
Of the 4942 studies initially retrieved, 17 studies were deemed relevant (Fig. 1). Five studies only reported NCD-related outcomes, seven only BRD-related outcomes, and five studies reported both outcomes separately or NCD and BRD combined (Table 1).
PRISMA flowchart of a systematic review on the effect of management practices on preweaned calf morbidity and mortality from neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) in beef herds. aGeneral mortality; bMorbidity and mortality from NCD and BRD.
Practices with statistically significant associations or effects detected: Neonatal calf diarrhea
Timing of the calving season
Two out of three PAs reported that early calving herds had higher odds of treating 10% of calves, and calves from early calving herds had a higher risk than those from late calving herds (A: 20a, 2c; NA: 4d (Table 2)). The directionality of findings was consistent, yet the certainty of this evidence was low (Table 3).
Summary of findings and risk of bias assessment (ROB) for breeding and calving season management practices with significant associations or effects on neonatal calf diarrhea (NCD) from studies within a systematic review on the effect of management practices on preweaned calf morbidity and mortality in beef cow–calf herds
a Suspect reverse causation or herds that use these practices have a higher baseline risk than those that do not (Clement et al., Reference Clement, King, Wittum, Biwer, Fleck, Salman and Odde1993; Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022)
Assessment of the certainty of findings of management practices with significant effects or associations using the GRADE approach within a systematic review on the effect of management practices on preweaned calf morbidity and mortality associated with neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) in beef cow–calf herds
Length of the calving season
One out of three PAs found that the odds of a herd having NCD detected were higher in those with longer calving seasons than those with shorter ones (A: 3b; NA: 2b, 4e [Table 2]). The directionality of the findings was inconsistent, and the certainty of the evidence was low (Table 3).
Other breeding and calving season management practices
Three out of four PAs found statistically significant associations of breeding and calving practices with NCD (A: 2a, 25r, 25a (Table 2); NA: 25b [Supplementary material 1]). However, the directionality of the findings for the timing of the breeding and calving of heifers and cows was contradictory across PAs. One PA showed that calves born in herds where heifers were bred before cows had a higher risk of NCD than those born in herds where heifers were not bred before cows (2a). However, another PA reported that calves from herds where heifers calved earlier than cows had a lower risk of NCD than those from herds where this practice was not used (25r). Also, calves from herds that frequently night-checked during the calving season had a higher risk of NCD than those from herds that did infrequent night checks (25a). No statistically significant association was found between routinely bedding cow–calf pairs and NCD in calves (25b).
Nutritional management of dams
Three out of six PAs reported statistically significant findings between dam supplementation and NCD (E: 17a, 17b, 17c; NE: 16a (Table 4); (NA): 2d, 2e [Supplementary material 1]). Three out of four PAs found a beneficial effect of supplementing dams with selenium (Se) (E: 17a, 17b, 17c; NE: 16a). Three of these PAs belonged to the same study, where different sources and doses of Se were compared (17a, 17b, 17c). Overall, fewer calves born from dams supplemented with 0.5 ppm of organic Se by Saccharomyces cerevisiae (17c) had NCD compared to those born from dams supplemented with 0.5 ppm of Se as sodium selenite (Na-selenite) (17b) or 0.1 ppm of Se as Na-selenite (17a). No impact was found in feeding corn pre- or post-calving (2d, 2e).
Summary of findings and risk of bias assessment (ROB) for nutritional management with significant associations or effects on neonatal calf diarrhoea (NCD) from studies within a systematic review on the effect of management practices on preweaned calf morbidity and mortality in beef cow–calf herds
ppm, parts per million; Se, selenium; Na-selenite, sodium selenite; Y-Se, organic selenium; SQ, subcutaneous;
a suspect reverse-causation or herds that use these practices have a higher baseline risk than those that do not (Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022).
Nutritional management of calves
One out of three PAs found a statistically significant association between nutritional management in calves and NCD (A: 25h; NA: 25g, 4f [Table 4]). Specifically, one PA (25h) evaluating the impact of mineral and vitamin supplementation given to newborn calves showed that calves from herds that gave vitamin D and A injections close to birth had a higher risk of NCD than calves born from herds that did not.
Biosecurity
One out of five PAs found a statistically significant association between biocontainment practices and NCD outcomes (A: 25y (Table 5); NA: 25c, 25d, 25f, 25w [Supplementary material 1]). A single PA reported a statistically significant association between the use of nursery pastures and the herd-level risk of NCD (25y). Still, within this PA, the directionality of findings varied depending on the timing in which NCD was considered. Calves from herds that did not sort their cow–calf pairs had a higher risk of NCD from 24 h of birth until 5 days of age than those from herds that sorted. However, calves from herds that sorted pairs had a higher risk of NCD from 6 days of age until one month than those from herds that did not sort. There was no significant impact of managing cows and heifers together during the winter feeding (25c), winter feeding and calving in one area (25d), animals remaining in the calving area until or close to the end of the calving season (25f), or the number of times pairs were gathered (25w).
Summary of findings and risk of bias assessment (ROB) for biosecurity and vaccination practices with significant associations or effects on neonatal calf diarrhea (NCD) from studies within a systematic review on the effect of management practices on preweaned calf morbidity and mortality in beef cow–calf herds
ETEC, enterotoxigenic Escherichia coli; SQ, subcutaneous.
a Suspect reverse-causation or herds that use these practices have a higher baseline risk than those that do not (Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022)
Dam vaccination against NCD-related pathogens
Eight out of 10 PAs that assessed the impact of vaccinating dams against pathogens involved in NCD found a statistically significant impact on NCD (E: 14a1, 14a2, 14b1, 14b2, 14c1, 14c2, 15b; NE: 15a; A: 3a; NA: 20b [Table 5]). Seven out of eight PAs showed consistent findings indicating that vaccination using vaccines that contained E. coli antigens prevented NCD (E: 14a1, 14a2, 14b1, 14b2, 14c1, 14c2, 15b; NE: 15a). Six PAs belonged to the same multiple-year study in which several variations in how the vaccine was administered were considered including whether vaccination was given to heifers or cows, the percentage of dams vaccinated in the group (0-100%), and the number of vaccine doses given (14a1, 14a2, 14b1, 14b2, 14c1, 14c2). Calves born in groups where either 100% (14a1) or 50% (14a2) of dams were vaccinated with two doses of vaccine had a lower risk of NCD than calves born to a group of placebo dams (i.e., 0%). Similarly, calves born to a group of 100% vaccinated heifers with two doses (14b1), as well as those born to a group of 100% vaccinated cows with two doses (14b2), had lower risks of disease than those born to groups of placebo heifers and cows (i.e., 0%). Also, calves born to heifers had a higher risk of NCD than those born to cows. This was because calves born to 100% vaccinated heifers with two doses had a higher risk of NCD than those born to 100% vaccinated cows with two doses. Also, calves born to placebo heifers had a higher risk than those born to placebo cows. Calves born to heifers with one vaccine dose had a higher risk of disease than calves born to vaccinated cows with one dose (14c1). However, no differences were found between calves born to cows with two vaccine doses and those born to cows with one vaccine dose (14c2). Similarly, fewer calves born to dams vaccinated with a 4-strain E. coli bacterin vaccine died from NCD than calves born to placebo dams (15b). However, herds vaccinated against NCD were reported to have higher odds of detecting NCD and a higher incidence of calf mortality from NCD than unvaccinated herds (3a). The certainty of this body of evidence could not be assessed given that the outcomes reported differed across PAs (i.e., NCD morbidity versus NCD mortality).
Dam vaccination against disease caused by Clostridium spp.
A single PA reported that calves from herds that vaccinated dams against clostridial disease during the spring before calving had a lower risk of NCD than those born to unvaccinated dams or dams vaccinated in the fall (A: 20d [Table 5]).
Calf vaccination against NCD-related pathogens
A single PA found that calves from herds that were vaccinated against NCD pathogens had a higher risk of NCD than those from unvaccinated herds (A: 25z [Table 5]).
Practices with statistically significant effects or associations detected: Bovine Respiratory Disease
Colostrum management
One out of six PAs reported that colostrum practices affected BRD outcomes (A: 22e [Table 6]; NA: 4a, 4b, 4c, 13d, 24c [Supplementary material 1]). In one PA, BRD was more frequently detected in herds where colostrum was provided to at least one calf using an oesophageal tube or nipple bottle than those that did not provide colostrum to any calf (22e). However, none of the criteria used to determine whether a calf required colostrum intervention (e.g., verifying if the calf has nursed by observing fullness of udder; 4a, 4b, 4c), the sources of colostrum (e.g. frozen colostrum; 13d), or methods of feeding colostrum (24c) affected the risk or rate of BRD or the odds of a calf having BRD.
Summary of findings and risk of bias assessment (ROB) for colostrum, breeding, and calving season management with significant associations or effects on bovine respiratory disease (BRD) from studies within a systematic review on the effect of management practices on preweaned calf morbidity and mortality in beef cow–calf herds
a Some batches were removed because of metaphylactic treatment, but it is unclear if these were from batches having BRD or not having BRD.
Timing of the calving season
Four out of five PAs found that the timing of the calving season affected BRD (A: 20a, 22j, 25p, 4d; NA: 24a [Table 6]). However, important differences existed between PAs. For example, one PA assessed whether the month that calving started was associated with the herd-level risk of disease (25p), and another assessed the impact of having >50% of calves born in January through April (22j). Overall, the directionality of the findings for herd-level outcomes was semi-consistent across PAs (20a, 22j, 25p, 4d). Two PAs found that herds that calved earlier or during winter and early spring had higher odds of treating 10% of calves and a higher cumulative incidence of disease than those calving later or in the spring (A: 20a, 22j). However, other PAs reported different directionality of findings. Calves from herds that started calving in December or April had a higher risk of disease than those from herds that started in March (25p). A fourth PA reported that the relationship between the timing of the calving season and the herd-level treatment risk of BRD was somewhat affected by other factors, including the incidence of NCD in the herd (4d). Therefore, for herd-level outcomes, the certainty of the findings was low (Table 3).
Length of the calving season
Three out of five PAs found that herds with longer calving seasons had higher odds of detecting BRD, a higher incidence within batches, or calves had a higher risk of BRD mortality than those with shorter seasons (A: 3b, 22c; 13a; NA: 21e, 4e [Table 6]). The directionality of the findings was consistent across PAs, but the overall certainty for the body of evidence on morbidity was low (Table 3).
Intensive calving area
Two out of four PAs reported that calving in intensive calving areas increased the odds of detecting BRD in herds or the incidence in herds (A: 22d, 25s; NA: 21h, 25t (Table 6)). The directionality of findings across PAs was semi-consistent, and the certainty of this evidence was low (Table 3).
Nutritional management
A single PA found that herds that used intensive grazing had higher odds of having over 5% of calves treated for BRD than those that did not use this practice (A: 21a [Table 7]).
Summary of findings and risk of bias assessment (ROB) for nutritional management with significant associations or effects on bovine respiratory disease (BRD) from studies within a systematic review on the effect of management practices on preweaned calf morbidity and mortality in beef cow-calf herds
a Some batches were removed because of metaphylactic treatment, but it is unclear if these were from batches having BRD or not having BRD.
Nutritional management of calves
Two out of eight PAs found an impact of nutritional management in calves and BRD outcomes (A: 13c, 22k [Table 7]; NA: 13b, 18i, 25m [Table 7], 4f, 25g, 25h [Supplementary material 1]). Two out of five PAs reported that calf supplementation with concentrate or maize or providing creep feeding was statistically associated with BRD outcomes (A: 13c, 22k; NA: 13b, 18i, 25m). However, the directionality of the findings was inconsistent. One PA reported that in calf batches where calves were fed maize silage, the incidence of BRD was lower than those not feeding silage (13c), while another reported that herds that fed supplemental feed had a higher cumulative incidence of BRD in calves than those that did not supplement (22k). Therefore, the certainty of this body of evidence was low (Table 3). Furthermore, injecting vitamins A, D, E, or Se to calves near birth was not associated with BRD outcomes (NA: 4f, 25g, and 25h).
Biosecurity
Six out of 12 PAs reported that external biosecurity practices impacted BRD outcomes (A: 22g, 22i, 25x, 18j, 18k, 18l; NA: 21d, 18d, 13i [Table 8], 13j, 21b, 25n [Supplementary material 1]). Five out of eight PAs showed that introducing certain types of cattle to the herd impacted disease and, in most cases, these introductions resulted in herds having higher odds of detection, incidence, or rates than herds that did not introduce cattle, although it varied between PAs as to which production group was actually associated with increased disease (A: 22g, 22i, 25x, 18j, 18k; NA: 21d, 18d, 13i). A higher proportion of herds that introduced any cattle had BRD detected in preweaned calves than those that did not (22g). Similarly, herds that introduced at least one calf to the operation from an outside source had a higher incidence of BRD than those that did not introduce animals (22i). The evidence on this body of evidence could not be assessed. Specifically, the evidence on dam introduction showed inconsistency in the directionality of findings (A: 25x, 18j; NA: 18d, 13i). One PA showed that calves from herds where any cows or calves were purchased during the pre-breeding period or calving season had a higher risk of BRD than those from herds that did not purchase during these periods (25x). Conversely, another PA reported that herds that imported bred heifers had lower BRD rates in calves than those that did not import bred heifers (18j). Therefore, the certainty concerning whether the introduction of dams increased the risk of BRD was low (Table 3). A single PA reported that herds that imported steers had higher BRD rates than those that did not (18k). Also, herds that had 1–2 or >30 visitors each month had higher disease rates than those with 3–5 or 6–30 (18l). No statistically significant relationship was found between the distance to other bovine units (13j), fence line contact with other herds (21b), and the use of communal pastures (25n) and BRD.
Summary of findings and risk of bias assessment (ROB) for biosecurity practices with significant associations or effects on bovine respiratory disease (BRD) from studies within a systematic review on the effect of management practices on preweaned calf morbidity and mortality in beef cow–calf herds
a Suspect reverse-causation or herds that use these practices have a higher baseline risk than those that did not (Woolums et al., Reference Woolums, Berghaus, Smith, Daly, Stokka, White, Avra, Daniel and Jenerette2018; Woolums et al., Reference Woolums, Berghaus, Smith, White, Engelken, Irsik, Matlick, Jones, Ellis, Smith, Mason and Waggoner2013)
b Multivariable analyses were reported because univariable p values were ≤0.30 and were not reported for each variable in the univariable analysis.
Six out of 9 PAs found that biocontainment practices affected BRD outcomes (A: 25w, 25k, 25r, 25y, 22h, 21g; NA: 18h [Table 8], 22f, 12e [Supplementary material 1]). Calves born in herds that gathered cow–calf pairs between calving and pasture turnout had a higher risk of BRD than those born from herds that did not gather pairs (25w). Also, calves born in herds that overwintered and calved in the same area (25k) or calved heifers and cows together (25r) had a higher risk of BRD than those that did not use these practices. Three out of four PAs showed that the use of nursery pastures impacted BRD outcomes (A: 25y, 22h, 21g; NA: 18h). Similarly to what was found for NCD, the directionality of findings across PAs was inconsistent to show that it prevented BRD. One PA found that calves from herds that sorted cow–calf pairs into nursery pastures had a lower risk of BRD than those from herds that did not sort (25y). However, two PAs showed that herds that sorted cow–calf pairs had higher odds of detecting at least one calf (22h) or treating at least 5% of their calves for BRD than those that did not (21g). Therefore, the certainty of this evidence was very low (Table 3). No statistically significant relationship was found between navel dipping (22f) or the frequency of using calving pens to house sick calves (12e) and BRD outcomes.
Dam vaccination against BRD-related pathogens
Two out of four PAs reported that vaccinating dams against BRD-related pathogens impacted BRD outcomes (A: 22b, 25l; NA: 13f, 18b [Table 9]). However, the directionality of findings was contradictory across PAs; thus, there was no consistent evidence proving that vaccination prevented BRD. One PA showed that calves from herds where dams were vaccinated had a lower risk of BRD than those from herds where dams were not vaccinated (25l), while another PA showed that BRD was more frequently detected in herds where dams were vaccinated than those that were not (22b). The certainty of this body of evidence could not be assessed due to differences in the pathogens targeted in the vaccines.
Summary of findings and risk of bias assessment (ROB) for vaccination practices with significant associations or effects on bovine respiratory disease (BRD) from studies within a systematic review on the effect of management practices on preweaned calf morbidity and mortality in beef cow–calf herds
a Suspect reverse-causation or herds that use these practices have a higher baseline risk than those that did not (Assié et al., Reference Assié, Bareille, Beaudeau and Seegers2009; Hanzileck et al., Reference Hanzileck, Renter, White, Wagner, Dargatz, Sanderson, Scott and Larson2013; Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022; Woolums et al., Reference Woolums, Berghaus, Smith, White, Engelken, Irsik, Matlick, Jones, Ellis, Smith, Mason and Waggoner2013).
b Some batches were removed because of metaphylactic treatment but it is unclear if these were from batches having BRD or not having BRD.
Calf vaccination against BRD-related pathogens
Five out of 11 PAs reported that vaccinating calves against BRD-related pathogens impacted BRD (E: 23a; A: 13e, 22a 25u, 18c; NE: 23b, 12a, 12b, 12c; NA: 18a, 18f [Table 9]). However, substantial differences existed among these PAs. For example, some reported calf-level outcomes (12a, 12b, 12c, 21a, 21b), while others herd- or batch-level ones (13e, 18a, 18c, 18f, 25u, 22a). Besides this, the vaccines used targeted different pathogens (e.g., BRSV in 13e and Pasteurella spp. in 18a). There was no consistency in the directionality of the findings showing a beneficial impact of vaccination across PAs. Only one PA reported that vaccinating calves twice with an inactivated BRSV, PIV3, and M. haemolytica vaccine reduced the number of calves requiring BRD treatment as well as reduced mortality compared to unvaccinated calves (23a). Conversely, four PAs found that herds or batches that reported vaccinating calves had a higher incidence, odds of detecting, or rates than those that did not vaccinate (13e, 22a, 25u, 18c). The certainty of this body of evidence could not be assessed given differences in outcomes and details concerning the vaccines.
Practices with no statistically significant associations or effects detected with NCD- or BRD-related outcomes
Supplementary material 1 summarizes practices without statistical associations or effects with NCD- or BRD-related outcomes or combined outcomes. These include colostrum management, breeding and calving management, nutritional management of dams and calves, and biosecurity practices.
Risk of bias assessment
This review included 87 PAs from observational studies and 16 from RCTs and CTs (Supplementary materials 2 and 3). For observational studies, 84 PAs had a high overall risk of bias, 3 had some concerns, and none had a low risk of overall bias. For RCTs and CTs, 14 PAs had a high overall risk of bias, two had some concerns, and none had a low risk of bias.
For PAs from observational studies, 77 had a high information bias. This was associated with a lack of details concerning the practices assessed (e.g., frequently moved to different pastures to manage grass intensively [21a]) and not providing case definitions for NCD and BRD (e.g., 2c). Seventy-eight PAs had selective reporting issues (e.g., univariable analyses were not shown (25n) or only practices with statistically significant associations kept in multivariable models were reported [4d]). Furthermore, 34 PAs had a high selection bias (e.g., participants were not selected using systematic methods or a convenience sample was used [4d]).
For PAs from RCTs and CTs, 11 had high risk of selective reporting (e.g. the results of logistic regressions were not shown [17a]). Nine PAs had a high risk of information bias, mainly because no details were provided about the blinding process (e.g., 12a). Similarly, intervention groups were sometimes commingled or not kept independent from each other (e.g., 23a). Also, case definitions were not given for NCD and BRD (e.g., 17a). Eight PAs had a high risk of confounding bias (e.g., there were no details concerning the randomization process [14a]).
Discussion
The overall findings suggest that most practices with statistically significant impacts were common for both NCD and BRD; however, differences concerning consistency in the directionality of findings suggest that their impact on these outcomes may vary. Most of the studies included in this review were observational, and thus the magnitude or directionality of findings are not as reliable as they should be for RCTs. However, given the high risk of bias in many of the RCTs and CTs, the evidence from these study types may also be unreliable. Therefore, although this review was able to summarize many of the practices that may help reduce calfhood morbidity and mortality, the low certainty of evidence means the findings should be interpreted with caution. Therefore, future well-conducted RCTs and observational studies should attempt to minimize bias to provide reliable evidence and support recommended practices.
Calves from early calving herds consistently had a higher risk of NCD than calves from later calving herds in studies conducted in the United States and Canada (Clement et al., Reference Clement, King, Wittum, Biwer, Fleck, Salman and Odde1993; Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016; Waldner et al., Reference Waldner, Jelinski and McIntyre-Zimmer2013). This finding aligns with what was described for calf mortality (Sanguinetti et al., Reference Santinello, Diana, De Marchi, Scali, Bertocchi, Lorenzi, Alborali and Penasa2025). This might be because herds that calve early usually calve, at least partially, inside barns to protect newborn calves from the cold, which typically involves herds being managed more intensively than those calving on pasture (Ganaba et al., Reference Ganaba, Bigras-Poulin, Bélanger and Couture1995; Radostits, Reference Radostits1991). In barns, calves are exposed to an environment more favourable to pathogen transmission between animals (Assié et al., Reference Assié, Bareille, Beaudeau and Seegers2009; Doeschl-Wilson et al., Reference Dewell, Hungerford, Keen, Laegreid, Griffin, Rupp and Grotelueschen2021). Calves born in winter are also more prone to cold stress, which can decrease the intestinal absorption of immunoglobulins from colostrum (Olson et al., Reference Olson, Papasian and Ritter1980). Similarly, the body of evidence for BRD showed semi-consistent directionality of findings (Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016; Waldner et al., Reference Waldner, Jelinski and McIntyre-Zimmer2013, Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022; Woolums et al., Reference Woolums, Berghaus, Smith, White, Engelken, Irsik, Matlick, Jones, Ellis, Smith, Mason and Waggoner2013). Hypothetically, for BRD, this semi-consistent directionality of findings could indicate that other factors may be affecting the relationship between the timing of the calving season and BRD (Dohoo et al., Reference Dohoo, Martin and Stryhn2009). For example, one PA reported that the incidence of NCD in herds influenced the incidence of BRD (Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016), suggesting NCD could be an intervening or moderator variable between the timing of the calving season and BRD (Dohoo et al., Reference Dohoo, Martin and Stryhn2009).
Herds with longer calving seasons consistently showed that they had higher odds of having BRD detected and a higher incidence of BRD than those from herds with shorter calving seasons (Assié et al., Reference Assié, Bareille, Beaudeau and Seegers2009; Dutil et al., Reference Dutil, Fecteau, Bouchard, Dutremblay and Paré1999; Woolums et al., Reference Woolums, Berghaus, Smith, White, Engelken, Irsik, Matlick, Jones, Ellis, Smith, Mason and Waggoner2013). These findings align with those described previously for mortality (Sanguinetti et al., Reference Santinello, Diana, De Marchi, Scali, Bertocchi, Lorenzi, Alborali and Penasa2025). It may be that herds with longer calving seasons have a more heterogeneous crop of calves in terms of age (Larson and Tyler, Reference Larson and Tyler2005). Therefore, younger calves are at higher risk of getting sick, given that they are challenged with increasing amounts of pathogens excreted by older calves, which are more resistant to disease (Larson and Tyler, Reference Larson and Tyler2005). Limiting the calving season to 80 days can minimize pathogen amplification, reducing the risk of disease (Chenoweth and Sanderson, Reference Chenoweth and Sanderson2005; WCCS, 2017). In contrast to BRD, only one out of three PAs reported that the odds of detecting NCD were higher in herds with longer seasons compared to those with shorter ones (Clement et al., Reference Clement, King, Wittum, Biwer, Fleck, Salman and Odde1993; Dutil et al., Reference Dutil, Fecteau, Bouchard, Dutremblay and Paré1999; Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016), and this body of evidence showed inconsistent directionality of findings. This may be because these studies had variable disease risks, and this could affect the impact of the practice (Clement et al., Reference Clement, King, Wittum, Biwer, Fleck, Salman and Odde1993; Dutil et al., Reference Dutil, Fecteau, Bouchard, Dutremblay and Paré1999; Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016). However, this hypothesis could not be assessed because some studies reported herd-level incidence of NCD (Clement et al., Reference Clement, King, Wittum, Biwer, Fleck, Salman and Odde1993; Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016), while another reported the percentage of herds where NCD was detected (Dutil et al., Reference Dutil, Fecteau, Bouchard, Dutremblay and Paré1999).
The bodies of evidence on intensive calving and intensive nutritional practices showed that these were associated with an increased risk of disease in calves. Specifically, calving in intensive areas, frequently monitoring cows during night-time, creep-feeding calves, intensive grazing, and calf mineral and vitamin supplementation close to birth were shown to increase the odds of detection of BRD in herds, the cumulative incidence of BRD, or the herd-level incidence of BRD and NCD (Assié et al., Reference Assié, Bareille, Beaudeau and Seegers2009; Hanzliceck et al., Reference Hanzileck, Renter, White, Wagner, Dargatz, Sanderson, Scott and Larson2013; Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022, Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022; Woolums et al., Reference Woolums, Berghaus, Smith, Daly, Stokka, White, Avra, Daniel and Jenerette2018, Reference Woolums, Berghaus, Smith, White, Engelken, Irsik, Matlick, Jones, Ellis, Smith, Mason and Waggoner2013). In studies conducted in the United States and Canada, findings were semi-consistent for intensive calving areas. Under field conditions, intensive calving practices are largely related to each other. For example, to monitor dams in case they need assistance at calving, they are typically placed in pens or paddocks close to the working facilities, and these sites usually have a high stocking density (Chenoweth and Sanderson, Reference Chenoweth and Sanderson2005). One hypothetical explanation of why intensive calving practices increase the risk of disease is that close to parturition, dams may shed high amounts of pathogenic agents, including Cryptosporidium (Thomson et al., Reference Thomson, Innes, Jonsson and Katzer2019), Salmonella (Muñoz-Vargas et al., Reference Muñoz-Vargas, Pempek, Proudfoot, Eastridge, Rajala-Schultz, Wittum and Habing2022), or BRoV and BCoV (Bulgin et al., Reference Bulgin, Ward, Barrett and Lane1989). Therefore, calves born in these sites are exposed to environments with a higher pathogen load than those born in more extensive calving settings and thus pathogen transmission rates may be higher. Besides this, herds that are more intensively managed are more likely to monitor the health status of calves, and consequently, this may be reflected in treating more calves compared to those more extensively managed. Given this, herds that manage calving intensively may need to consider additional practices, such as increased bedding, using nursery pastures (i.e., Foothills calving system), or moving the calving area during the season (i.e., Sandhills calving system) to reduce environmental contamination. However, only one PA found that herds that used nursery pastures had a lower risk of NCD from 1 to 5 days of age than those not using them (Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022). Yet, no details concerning age differences between calves in the same pasture or stocking density in the pasture were provided. Furthermore, none assessed aspects of the Sandhills calving system. These two practices where calves are segregated by age are important given that they have been promoted in Canada and the US (Radostits and Acres, Reference Radostits and Acres1983; United States Department of Agriculture Animal and Plan Health Inspection Service Veterinary Services National Animal Health Monitoring System, 2021). Similarly, intensive nutritional practices increase the bunching of the herd. For example, creep-feeding tends to crowd calves around feed bunks. Therefore, although creep feeding may have benefits on post-weaning morbidity and mortality (Chenoweth and Sanderson, Reference Chenoweth and Sanderson2005), this practice may be detrimental during the preweaning stage if not done with attention to environmental conditions that may promote the spread of pathogens.
A limited body of evidence showed that the source of Se used to supplement dams affected the incidence of NCD in calves (Guyot et al., Reference Guyot, Spring, Andrieu and Rollin2007). Supplementing with organic Se was more beneficial than Na-selenite, regardless of the dose used. This is likely because organic forms of Se have higher absorption and bioavailability (Arshad et al., Reference Arshad, Ebeid and Hassan2021; Gunter et al., Reference Gunter, Beck and Phillips2003), and these have been associated with higher concentrations in blood and milk than those supplemented with inorganic forms (Slavik et al., Reference Slavik, Illek, Brix, Hlavicova, Rajmon and Jilek2013). Still, the benefits of Se supplementation of dams appear to be more evident in enhancing reproduction (Gunter et al., Reference Gunter, Beck and Phillips2003) than in benefitting calfhood health, given that the latter is more indirect. There are a number of additional factors that can impact if calves benefit from dam supplementation. These include the product itself (i.e., bioavailability), the dams’ initial mineral status, the efficiency of the mineral to pass through the placenta (Gooneratne and Christensen, Reference Gooneratne and Christensen1989; Pavlata et al., Reference Pavlata, Prasek, Podhorsk, Pechova and Haloun2003), colostrum, and milk (Slavik et al., Reference Slavik, Illek, Brix, Hlavicova, Rajmon and Jilek2013), and finally, the ability of the calf to nurse from its dam.
While none of the biosecurity practices assessed were associated with prevention of NCD or BRD, several practices were shown to be risk factors that increase the incidence of disease in herds. In general terms, introduction of animals to the herd increased the incidence of BRD (Hanzlicek et al., Reference Hanzileck, Renter, White, Wagner, Dargatz, Sanderson, Scott and Larson2013; Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022; Woolums et al., Reference Woolums, Berghaus, Smith, White, Engelken, Irsik, Matlick, Jones, Ellis, Smith, Mason and Waggoner2013). Similarly, another study not included in this review found that introducing more than 10 bulls in the herd increased the odds of NCD and BRD outbreaks (Wennekamp et al., Reference Wennekamp, Waldner, Parker, Windeyer, Larson and Campbell2021). This study was excluded from this review because the outbreak definition included other animals besides preweaned beef calves. Possible explanations for why the introduction of animals increases the risk of BRD include that purchased cattle are usually transported, which triggers stress, affects immunocompetence, and increases pathogen shedding (Chen et al., Reference Chen, Bernardino, Fausak, Van Noord and Maier2022; Taylor et al., Reference Taylor, Fulton, Lehenbauer, Step and Confer2010). Additionally, upon arrival, unless new purchases are quarantined, these are commingled with the herd, where social mixing takes place and exposes the herd to new pathogens (Chen et al., Reference Chen, Bernardino, Fausak, Van Noord and Maier2022; Hubbard et al., Reference Hubbard, Foster and Daigle2021). However, the specific body of evidence assessing the introduction of dams did not show consistent directionality of findings (Assié et al., Reference Assié, Bareille, Beaudeau and Seegers2009; Hanzileck et al., Reference Hanzileck, Renter, White, Wagner, Dargatz, Sanderson, Scott and Larson2013; Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022). One study reported that herds that introduced bred heifers had a lower rate of BRD than those that did not (Hanzileck et al., Reference Hanzileck, Renter, White, Wagner, Dargatz, Sanderson, Scott and Larson2013). This inconsistency could be because other management practices that were not reported could have potentially mitigated the impact of the introduction. For example, maybe these herds that introduced heifers had a set of disease control practices in place when introducing them, including purchasing from one trusted source, avoiding long-distance travelling, vaccination prior to introduction, and quarantining animals upon arrival (Chenoweth and Sanderson, Reference Chenoweth and Sanderson2005; Sanguinetti et al., Reference Santinello, Diana, De Marchi, Scali, Bertocchi, Lorenzi, Alborali and Penasa2025; Santinello et al., Reference Sanguinetti, Ganshorn, Agbese and Windeyer2024; Wennekamp et al., Reference Wennekamp, Waldner, Parker, Windeyer, Larson and Campbell2021).
The directionality of findings for the use of nursery pastures and calf vaccination against BRD-related pathogens was inconsistent in showing that these practices prevented BRD (Assié et al., Reference Assié, Bareille, Beaudeau and Seegers2009; Hanzileck et al., Reference Hanzileck, Renter, White, Wagner, Dargatz, Sanderson, Scott and Larson2013; Makoschey et al., Reference Makoschey, Bielsa, Oliviero, Roy, Pillet, Dufe, Valla and Cavirani2008; Van Donkersgoed et al., Reference Van Donkersgoed, Potter, Mollison and Harland1994; Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022; Woolums et al., Reference Woolums, Berghaus, Smith, White, Engelken, Irsik, Matlick, Jones, Ellis, Smith, Mason and Waggoner2013). As mentioned before, the use of nursery pastures or a series of calving pastures is intended to segregate calves by age to reduce the pathogen challenge to which newborn calves are exposed. This prevents newborn calves from being exposed to high pathogen concentrations in their environments (Chenoweth and Sanderson, Reference Chenoweth and Sanderson2005) and thus helps reduce the risk of disease in calves. Vaccination may enhance antigen-specific immunity (Thrusfield and Christley, Reference Thrusfield and Christley2018) and decrease the probability or severity of disease, including NCD and BRD (Callan and Garry, Reference Callan and Garry2002). Similar to the findings of this review, two other reviews that included challenge studies found scarce evidence to support or refute the practice (Chamorro and Palomares, Reference Chamorro and Palomares2020; Theurer et al., Reference Theurer, Larson and White2015). Reasons for the conflicting directionality of findings of the bodies of evidence of these two practices could be related to the fact that in some scenarios, herds that use these practices have a higher risk of disease than those that do not (Waldner et al., Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022). In this review, most studies are cross-sectional and cannot provide evidence on the temporal relationship between exposure and outcome (Van der Stede, Reference der Stede Wa2014; Dohoo et al., Reference Dohoo, Martin and Stryhn2009); thus, estimates are prone to reverse causation. Future RCTs or cohort studies could provide evidence on temporality and help elucidate the impact of various disease control practices. The cohort study design could be particularly beneficial given that it would be somewhat difficult to randomize cattle for some of the practices mentioned, such as calving pasture management and the biosecurity practices outlined above.
The directionality of findings could also be affected by the disease risk impacting the effectiveness of the practices. For example, PAs compiled for calf vaccination came from studies with disease risks varying from 3% to 28% (Hanzileck et al., Reference Hanzileck, Renter, White, Wagner, Dargatz, Sanderson, Scott and Larson2013; Makoschey et al., Reference Makoschey, Bielsa, Oliviero, Roy, Pillet, Dufe, Valla and Cavirani2008; Van Donkersgoed et al., Reference Van Donkersgoed, Potter, Mollison and Harland1994). Nevertheless, no clear pattern showed that PAs with significant associations or effects came from studies with higher disease risk compared to those with non-significant associations or effects from studies with lower disease risks, as seen elsewhere (Sanguinetti et al., Reference Santinello, Diana, De Marchi, Scali, Bertocchi, Lorenzi, Alborali and Penasa2025). Another potential reason for the inconsistent directionality of findings for vaccination is the interference by maternal antibodies when attempting to vaccinate calves (Windeyer and Gamsjäger, Reference Windeyer and Gamsjäger2019). For example, an RCT where calves were subcutaneously vaccinated twice from 3 to 5 weeks of age did not find a significant benefit of vaccination (Van Donkersgoed et al., Reference Van Donkersgoed, Potter, Mollison and Harland1994). However, no details were provided concerning dam vaccination nor the transfer of passive immunity (TPI) in these calves. Therefore, calf vaccination against BRD-related pathogens is likely an area that requires more well-conducted RCTs to help determine for which herds this practice is more beneficial to be implemented, as well as optimum timing and routes of administration. This is because there is some evidence that parenteral vaccination in the face of maternal antibodies may activate the cell-mediated response (Platt et al., Reference Platt, Widel, Kesl and Roth2009) and prime the immune system (Endsley et al., Reference Endsley, Roth, Ridpath and Neill2003), while intranasal vaccination may circumvent maternal antibodies and offers more immediate protection to calves (Ellis et al., Reference Ellis, Gow, Mahan and Leyh2013). Similarly, more research is needed to optimize the use of the nursery pastures or a series of calving pastures, as mentioned previously for NCD.
Vaccinating dams using vaccines that contained E. coli agents reduced the risk of NCD morbidity and mortality (Cornaglia et al., Reference Cornaglia, Fernández, Gottschalk, Barrandeguy, Luchelli, Pasini, Saif, Parraud, Romat and Schudel1992; Myers, Reference Myers1980). This aligns with the findings of another systematic review, which included dairy studies (Maier et al., Reference Maier, Breitenbuecher, Gomez, Samah, Fausak and Van Noord2022). Calves born from vaccinated dams have higher serum antibodies targeting E. coli and reduced odds of morbidity and mortality compared to those born from unvaccinated dams (Gamsjäger et al., Reference Gamsjäger, Haines, Lévy, Pajor, Campbell and Windeyer2023a; Wileman et al., Reference Wileman, Thomson, Olson, Jaeger, Pacheco, Bolte, Burkhardt, Emery and Straub2011). Therefore, by vaccinating dams according to label instructions (Compendium of Veterinary Products-Canada edition, 2021) and ensuring that the TPI is adequate (Gull, Reference Gull2022; Tizard, Reference Tizard2021), dam vaccination containing E. coli agents may help prevent NCD.
A limited body of evidence indicated that vaccinating dams against clostridial disease reduced the risk of NCD and that vaccination against BRD-related pathogens prevented BRD (Waldner et al., Reference Waldner, Jelinski and McIntyre-Zimmer2013, Reference Waldner, Wilhelm, Windeyer, Parker and Campbell2022). Another scoping review also described a scarcity of findings to support clostridial vaccination for NCD prevention (Maier et al., Reference Maier, Breitenbuecher, Gomez, Samah, Fausak and Van Noord2022). However, vaccination of dams against clostridial pathogens has been described as the most helpful practice to prevent NCD caused by Clostridium perfringens types C and D (Gull, Reference Gull2022). Furthermore, an expert consensus study conducted in western Canada reported that dam vaccination was useful to prevent calf mortality ‘very much for most herds’ (Sanguinetti et al., Reference Santinello, Diana, De Marchi, Scali, Bertocchi, Lorenzi, Alborali and Penasa2025). Similarly, calves with higher antibody titers against BHV1, PIV3, and BVDV had lower odds of being treated or dying than those with lower antibody titers (Gamsjäger et al., Reference Gamsjäger, Haines, Lévy, Pajor, Campbell and Windeyer2023a). Therefore, dam vaccination against clostridial pathogens and BRD-related agents may be beneficial, although reliable evidence is still lacking.
The overall strategy used in this review to retrieve relevant studies seemed appropriate for most practices; however, it may have been somewhat limited for retrieving colostrum management studies. The exclusion criteria removed studies where calf morbidity and mortality were not recorded for at least three months of age, meaning that colostrum studies that followed calves for a shorter period of time were not included. A recent systematic review assessing TPI in beef and dairy calves reported that cohort and RCTs had an average follow-up of 75.5 days long (Thompson and Smith, Reference Thompson and Smith2022). Among the included studies, most were cross-sectional studies with most doing follow-up during the entire preweaning period and did not report statistically significant associations with the outcomes of interest (Assié et al., Reference Assié, Bareille, Beaudeau and Seegers2009; Murray et al., Reference Murray, Fick, Pajor, Barkema, Jelinski and Windeyer2016; Pearson et al., Reference Pearson, Pajor, Campbell, Levy, Caulkett and Windeyer2019b; Pisello et al., Reference Pisello, Sala, Rueca, Passamonti, Pravettoni, Ranciati, Boccardo, Bergero and Forte2021; Woolums et al., Reference Woolums, Berghaus, Smith, White, Engelken, Irsik, Matlick, Jones, Ellis, Smith, Mason and Waggoner2013). However, cross-sectional studies are known to provide evidence of associations and not causation (Dohoo et al., Reference Dohoo, Martin and Stryhn2009), and most of them analysed their findings using multivariable models, the limitations of which have been extensively discussed elsewhere (Sanguinetti et al., Reference Santinello, Diana, De Marchi, Scali, Bertocchi, Lorenzi, Alborali and Penasa2025). Therefore, it is likely that these non-significant findings are related to the study design and statistical methods used rather than colostrum management not impacting NCD and BRD. Additionally, many colostrum studies assessed either the relationship between colostrum management and TPI (Gamsjäger et al., Reference Gamsjäger, Haines, Lévy, Pajor, Campbell and Windeyer2023b) or the relationship between the TPI and health outcomes (Dewell et al., Reference Doeschl-Wilson, Knap, Opriessnig and More2006; Gamsjäger et al., Reference Gamsjäger, Haines, Lévy, Pajor, Campbell and Windeyer2023a), but not the relationship between colostrum management and health. The intermediate outcome of TPI is relevant because calves with failed TPI have a higher risk of morbidity and mortality than those with adequate TPI (Homerosky et al., Reference Homerosky, Timsit, Pajor, Kastelic and Windeyer2017; Raboisson et al., Reference Raboisson, Trillat and Cahuzac2016; Thompson and Smith, Reference Thompson and Smith2022; Todd et al., Reference Todd, McGee, Tiernan, Crosson, O’Riordan, McClure, Lorenz and Earley2018; Windeyer et al., Reference Windeyer, Leslie, Godden, Hodgins, Lissemore and LeBlanc2014; Wittum and Perino, Reference Wittum and Perino1995). However, the inclusion criteria stated that only studies assessing the direct relationship between practices and morbidity and mortality could be included. Finally, other syndromes besides NCD and BRD, such as arthritis and omphalitis (Filteau et al., Reference Filteau, É, Fecteau, Dutil and DuTremblay2003; Waldner and Rosengren, Reference Waldner and Rosengren2009), were often included in morbidity outcomes, and these studies violated the inclusion criteria, again affecting the retrieval of relevant colostrum management studies. Given these limitations, the findings for colostrum management in this review may be unreliable, and there is still a gap in knowledge concerning recommended colostrum practices to prevent NCD and BRD.
Conclusions
This review compiled evidence concerning the impacts of management practices on calf health and its potential implications for guiding recommendations for western Canadian beef cow-calf herds. Evidence showed that many breeding and calving management, nutritional management, biosecurity, and vaccination can impact beef calf health. However, the consistency in the directionality of findings depended on the specific outcome NCD or BRD, suggesting that the impact of practices may vary depending on the outcome assessed. Furthermore, the impact of practices may also vary depending on other management, host, and environmental factors that were not assessed in the reported studies. Overall, the certainty of the bodies of evidence was low, meaning that more well-executed RCTs and cohort studies are needed to provide reliable evidence on the directionality of findings and the magnitude of their effects.
Open access
