Invited opinion paper
Opinion paper: Are we on the right track toward livestock sector sustainability?
- I. Köhler-Rollefson, D. Steane
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- Published online by Cambridge University Press:
- 13 July 2017, pp. 2111-2112
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Breeding and genetics
Research Article
Evaluation of longevity modeling censored records in Nellore
- D. A. Garcia, G. J. M. Rosa, B. D. Valente, R. Carvalheiro, G. A. Fernandes Júnior, L. G. Albuquerque
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- 23 May 2017, pp. 2113-2119
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The aim of the present study was to evaluate the prediction ability of models that cope with longevity phenotypic expression as uncensored and censored in Nellore cattle. Longevity was defined as the difference between the dates of last weaned calf and cow birth. There were information of 77 353 females, being 61 097 cows with uncensored phenotypic information and 16 256 cows with censored records. These data were analyzed considering three different models: (1) Gaussian linear model (LM), in which only uncensored records were considered; and two models that consider both uncensored and censored records: (2) Censored Gaussian linear model (CLM); and (3) Weibull frailty hazard model (WM). For the model prediction ability comparisons, the data set was randomly divided into training and validation sets, containing 80% and 20% of the records, respectively. There were considered 10 repetitions applying the following restrictions: (a) at least three animals per contemporary group in the training set; and (b) sires with more than 10 progenies with uncensored records (352 sires) should have daughters in the training and validation sets. The variance components estimated using the whole data set in each model were used as true values in the prediction of breeding values of the animals in the training set. The WM model showed the best prediction ability, providing the lowest χ2 average and the highest number of sets in which a model had the smallest value of χ2 statistics. The CLM and LM models showed prediction abilities 2.6% and 3.7% less efficient than WM, respectively. In addition, the accuracies of sire breeding values for LM and CLM were lower than those obtained for WM. The percentages of bulls in common, considering only 10% of sires with the highest breeding values, were around 75% and 54%, respectively, between LM–CLM and LM–WM models, considering all sires, and 75% between LM–CLM and LM–WM, when only sires with more than 10 progenies with uncensored records were taken into account. These results are indicative of reranking of animals in terms of genetic merit between LM, CLM and WM. The model in which censored records of longevity were excluded from the analysis showed the lowest prediction ability. The WM provides the best predictive performance, therefore this model would be recommended to perform genetic evaluation of longevity in this population.
Inferring causal structures and comparing the causal effects among calving difficulty, gestation length and calf size in Japanese Black cattle
- K. Inoue, M. Hosono, Y. Tanimoto
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- 08 May 2017, pp. 2120-2128
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The objectives of this study were to infer phenotypic causal networks involving gestation length (GL) and calving difficulty (CD) for the primiparity of 1850 Japanese Black heifers, and the birth weight (BWT), withers height (WH) and chest girth (CHG) of their full blood calves, and to compare the causal effects among them. The inductive causation (IC) algorithm was employed to search for causal links among these traits; it was applied to the posterior distribution of the residual (co)variance matrix of a multiple-trait sire-maternal grand sire (MGS) model. The IC algorithm implemented with 95% and 90% highest posterior density intervals detected only one structure with links between GL and BWT (WH or CHG) and between BWT (WH or CHG) and CD, although their directions were not resolved. Therefore, a possible causal structure based on the networks obtained from the IC algorithm [GL→BWT (WH or CHG)→CD] was fitted using a structural equation model to infer causal structure coefficients between the traits. The structural coefficients of GL on BWT and of BWT on GL on the observable scale showed that an extra day of GL led to a 270-g gain in BWT, and a 1-kg increase in BWT increased the risk for dystocia by 1.1%, in the causal structure. Similarly, an increase in GL by 1 day resulted in a 2.1 (2.0)-mm growth in WH (CHG), and a 1-cm increase in WH (CHG) increased the risk of dystocia by 1.2% (0.9%). The structural equation model was also fitted to alternative causal structures, which involved the addition of a directed link from GL to CD, or GL→CD to the structures described above. The inferred structural coefficients with the alternative structures were almost the same as the corresponding ones that had GL→BWT (WH or CHG)→CD. However, the direct causal effect of the extra link from GL on CD was similar to the indirect causal effect of GL through the mediating effect of BWT (WH or CHG) on CD and significant (P<0.05). This suggest that maternal genetic effects might not be removed completely from the residual variance components in the sire-MGS model, and the application of the IC algorithm to the variances from the model could detect an incorrect structure. Nonetheless, fitting the structural equation model to the causal structure provided useful information such as the magnitude of the causal effects between the traits.
A model to infer the demographic structure evolution of endangered donkey populations
- F. J. Navas, J. Jordana, J. M. León, C. Barba, J. V. Delgado
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- 16 May 2017, pp. 2129-2138
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Stemming from The Worldwide Donkey Breeds Project, an initiative aiming at connecting international researchers and entities working with the donkey species, molecularly tested pedigree analyses were carried out to study the genetic diversity, structure and historical evolution of the Andalusian donkey breed since the 1980s to infer a model to study the situation of international endangered donkey breeds under the remarkably frequent unknown genetical background status behind them. Demographic and genetic variability parameters were evaluated using ENDOG (v4.8). Pedigree completeness and generation length were quantified for the four gametic pathways. Despite mean inbreeding was low, highly inbred animals were present in the pedigree. Average coancestry, relatedness, and non-random mating degree trends were computed. The effective population size based on individual inbreeding rate was about half when based on individual coancestry rate. Nei’s distances and equivalent subpopulations number indicated differentiated farms in a highly structured population. Although genetic diversity loss since the founder generations could be considered small, intraherd breeding policies and the excessive contribution of few ancestors to the gene pool could lead to narrower pedigree bottlenecks. Long average generation intervals could be considered when reducing inbreeding. Wright’s fixation statistics indicated slight inbreeding between farms. Pedigree shallowness suggested applying new breeding strategies to reliably estimate descriptive parameters and control the negative effects of inbreeding, which could indeed, mean the key to preserve such valuable animal resources avoiding the extinction they potentially head towards, making the present model become an international referent when assessing endangered donkey populations.
Nutrition
Research Article
Immune responses, intestinal microbiota, performance and blood characteristics of Japanese quail fed on diets containing camphor
- A. Sedaghat, M. A. Karimi Torshizi
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- 23 May 2017, pp. 2139-2146
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This study aimed to investigate the effect of supplemental camphor on the performance and immune functions of Japanese quail by feeding graded levels (0 (control), 250, 500, 750, 1000, 5000 or 10 000 ppm) of camphor during a 42-day feeding trial. In all, 280 1-day-old quail chicks were randomly assigned into 28 cages of 10 chicks each with separate feeders. The results clearly demonstrated that camphor did not have a significant effect on BW, BW gain, total experimental average daily feed intake, feed conversion ratio, internal organ relative weights and biochemical parameters such as uric acid, albumin, total protein and triglyceride; however, plasma cholesterol concentration was significantly different in a linear manner, in which 500 ppm of camphor resulted in a lower level of cholesterol. Alternatively, greater concentrations of glucose and high-density lipoprotein (HDL) were also found in 5000 and 1000 ppm of camphor groups, respectively. Cellular responses to the phytohaemagglutinin-P and 2,4-dinitro 1-chlorobenzene skin test were not influenced by dietary camphor. Humoral responses to secondary sheep red blood cells, avian influenza virus (AIV) and Newcastle disease virus (NDV) immunisations were positively influenced by camphor supplementation, in which greater secondary response to sheep erythrocytes belonged to 750 and 1000 ppm of camphor groups; whereas, diet supplementation with camphor had no significant effect on lymphoid organ weights and heterophil-to-lymphocyte ratio. The greatest AIV antibody titers were seen in groups, which received 1000 and 5000 ppm of camphor (P<0.05) and the values of NDV antibody titers increased with an increase in the camphor consumption. Furthermore, dietary inclusion of 500 ppm of camphor positively decreased coliform populations in the gastrointestinal tract (GIT). In addition, an increase in lactic acid bacteria was also observed in quails, which were fed on the diets containing 750 ppm camphor. Collectively, these data suggest that as a phytogenic feed additive, camphor may effectively act as a modulator of health status (by increasing glucose and HDL), GIT microbiota and immunological responses of the Japanese quail.
The effect of dietary faba bean and non-starch polysaccharide degrading enzymes on the growth performance and gut physiology of young turkeys
- D. Mikulski, J. Juskiewicz, B. Przybylska-Gornowicz, E. Sosnowska, B. A. Slominski, J. Jankowski, Z. Zdunczyk
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- 16 May 2017, pp. 2147-2155
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The aim of this study was to investigate the effect of dietary replacement of soya bean meal (SBM) with faba bean (FB) and a blend of non-starch polysaccharide (NSP) degrading enzymes on the gastrointestinal function, growth performance and welfare of young turkeys (1 to 56 days of age). An experiment with a 2×2 factorial design was performed to compare the efficacy of four diets: a SBM-based diet and a diet containing FB, with and without enzyme supplementation (C, FB, CE and FBE, respectively). In comparison with groups C, higher dry matter content and lower viscosity of the small intestinal digesta were noted in groups FB. The content of short-chain fatty acids (SCFAs) in the small intestinal digesta was higher in groups FB, but SCFA concentrations in the caecal digesta were comparable in groups C and FB. In comparison with control groups, similar BW gains, higher feed conversion ratio (FCR), higher dry matter content of excreta and milder symptoms of footpad dermatitis (FPD) were noted in groups FB. Enzyme supplementation increased the concentrations of acetate, butyrate and total SCFAs, but it did not increase the SCFA pool in the caecal digesta. The enzymatic preparation significantly improved FCR, reduced excreta hydration and the severity of FPD in turkeys. It can be concluded that in comparison with the SBM-based diet, the diet containing 30% of FB enables to achieve comparable BW gains accompanied by lower feed efficiency during the first 8 weeks of rearing. Non-starch polysaccharide-degrading enzymes can be used to improve the nutritional value of diets for young turkeys, but more desirable results of enzyme supplementation were noted in the SBM-based diet than in the FB-based diet.
Dietary supplementation with a nucleotide-rich yeast extract modulates gut immune response and microflora in weaned pigs in response to a sanitary challenge
- S. M. Waititu, F. Yin, R. Patterson, A. Yitbarek, J. C. Rodriguez-Lecompte, C. M. Nyachoti
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- Published online by Cambridge University Press:
- 20 June 2017, pp. 2156-2164
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An experiment was carried out to evaluate the short-term effect of supplementing a nucleotide-rich yeast extract (NRYE) on growth performance, gut structure, immunity and microflora of piglets raised under sanitary and unsanitary conditions. A total of 84, 21-day old piglets were used in this study; 42 piglets were raised in a room designated as the clean room that was washed once per week, whereas the other 42 piglets were raised in a room designated as the unclean room in which 7 kg of manure from the sow herd was spread on each pen floor on day 1 and 7 and the room was not washed throughout the experiment. The pigs were fed a corn–soybean meal-based diet without or with 0.1% NRYE. Each treatment had 7 replicate pens in each room, and each pen housed 3 pigs. Feed disappearance and BW were recorded on day 1 and 14. On day 14, one pig per pen was euthanized to collect ileum, mesenteric lymph nodes and spleen tissues, and cecum and colon digesta. Overall, NRYE supplementation did not affect growth performance in both clean and unclean conditions, improved kidney weight in both clean (P=0.0002) and unclean room (P<0.0001) and tended to improve the villus height/crypt depth ratio in the clean room (P=0.073). Supplementing NRYE was associated with upregulation of Ileal programmed cell death gene-1 (P=0.0003), interleukin (IL)-1β (P<0.0001), IL-6 (P=0.0003), IL-10 (P<0.0001) and tumor necrosis factor-α (TNF-α) (P<0.0001) in pigs raised in the unclean room. Supplementing the NRYE in pigs raised in the clean room suppressed growth of cecal Enterobacteriacea (P<0.0001) members and colonic Enterococcus spp. (P<0.019), improved proliferation of cecal Lactobacillus spp. (P<0.002) and colonic Clostridium cluster IV (P<0.011) and XVIa members (P<0.0002). Supplementing the NRYE in the unclean room improved proliferation of cecal Clostridium cluster IV (P<0.026) and suppressed proliferation of colonic Enterococcus spp. (P<0.037). In conclusion, supplementing the NRYE to piglets under unsanitary conditions improved ileal immune response by upregulating inflammatory cytokines, and positively modulated proliferation of beneficial gut bacteria and suppression of harmful ones in both clean and unclean rooms.
Energy and protein requirements of Santa Ines lambs, a breed of hair sheep
- E. S. Pereira, F. W. R. Lima, M. I. Marcondes, J. P. P. Rodrigues, A. C. N. Campos, L. P. Silva, L. R. Bezerra, M. W. F. Pereira, R. L. Oliveira
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- Published online by Cambridge University Press:
- 05 June 2017, pp. 2165-2174
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An experiment was carried to evaluate the energy and protein requirements for the growth and maintenance of lambs of different sex classes. In all, 38 hair lambs (13.0±1.49 kg initial BW and 2 months old) were allocated in a factorial design with diet restriction levels (ad libitum, 30% and 60% feed restriction) and sex classes (castrated and non-castrated males). Four animals from each sex class were slaughtered at the beginning of the trial as a reference group to estimate the initial empty BW and body composition. The remaining lambs were weighed weekly to calculate BW gain (BWG), and when the animals fed ad libitum reached an average BW of 30 kg, all of the experimental animals were slaughtered. Before slaughter, fasted BW (FBW) was determined after 18 h without feed and water. Feed restriction induced reductions in body fat and energy concentration, whereas water restriction showed the opposite effect, and the protein concentration was not affected. The increase in BW promoted increases in body fat and energy content, and these increases were greater in castrated lambs, whereas the protein content was similar between classes tending to stabilize. The net energy required for gain (NEg) and the net protein required for gain (NPg) were not affected by sex class; therefore, an equation was generated for the combined results of both castrated and non-castrated lambs. The NEg varied from 1.13 to 2.01 MJ/day for lambs with BW of 15 and 30 kg and BWG of 200 g. The NPg varied from 24.57 to 16.33 g/day for lambs with BW of 15 and 30 kg and BWG of 200 g. The metabolizable energy efficiency for gain (kg) was 0.37, and the metabolizable protein efficiency for gain (kpg) was 0.28. The net energy required for maintenance (NEm) and the net requirement of protein for maintenance (NPm) did not differ between castrated and non-castrated lambs, with values of 0.241 MJ/kg FBW0.75 per day and 1.30 g/kg FBW0.75 per day, respectively. The metabolizable energy efficiency for maintenance (km) was 0.60, and the efficiency of metabolizable protein use for maintenance (kpm) was 0.57. Nutritional requirements for growth and maintenance did not differ between castrated and non-castrated lambs. This study emphasizes the importance of updating the tables of international committees and of including data obtained from studies with sheep breeds raised in tropical conditions, with the purpose of improving the productive efficiency of the animals
Supplementing high-quality fresh forage to growing lambs fed a total mixed ration diet led to higher intake without altering nutrient utilization
- A. Pérez-Ruchel, J. L. Repetto, C. Cajarville
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- Published online by Cambridge University Press:
- 08 May 2017, pp. 2175-2183
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The effect of supplementing high-quality fresh forage, mainly based on alfalfa, to growing lambs fed with decreasing levels of total mixed ration (TMR) was studied on intake, digestion and ruminal environment. In total, 24 catheterized lambs (25.2±3.67 kg) housed in individual metabolism cages were assigned to one of four treatment diets: ‘TMR100’: TMR offered ad libitum; ‘TMR75’ and ‘TMR50’: TMR at a level of 0.75 and 0.50 of potential intake, respectively, complemented with fresh forage without restriction; ‘TMR0’: only fresh forage ad libitum. The feeding behavior, nutrient intake and digestibility, kinetics of passage and rumen environment were evaluated. As the level of TMR in the diet decreased, lambs increased the forage intake and spent more time eating and ruminating, less time resting and demonstrated a higher rate of intake. Those changes resulted in a higher nutrient intake of dry matter, organic matter, nitrogen, NDF and ADF, but a slightly lower organic matter digestibility, while no differences were detected in the output rate of particles. As a consequence, with the decrease of TMR and increase of forage intake, the ingested energy increased. Higher ruminal pH and NH3–N concentrations were observed for lower levels of TMR in the diet. The total volatile fatty acids, acetate and propionate concentrations presented a quadratic response. Total volatile fatty acids and acetate concentrations were higher and propionate concentration was lower in lambs consuming mixed diets (TMR50 and TMR75). We concluded that the inclusion of high-quality fresh forage in a combined diet with TMR in lambs had positive effects on nutrient intake without negative consequences on digestion and rumen environment.
Supplementation of grazing beef cows during gestation as a strategy to improve skeletal muscle development of the offspring
- D. C. Marquez, M. F. Paulino, L. N. Rennó, F. C. Villadiego, R. M. Ortega, D. S. Moreno, L. S. Martins, D. M. de Almeida, M. P. Gionbelli, M. R. Manso, L. P. Melo, F. H. Moura, M. S. Duarte
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- Published online by Cambridge University Press:
- 02 June 2017, pp. 2184-2192
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The appropriate supply of nutrients in pregnant cows has been associated with the optimal development of foetal tissues, performance of their progeny and their meat quality. The aim of this study was to evaluate supplementation effects of grazing cows in different stages of gestation on skeletal muscle development and performance of the progeny. Thereby, 27 Nellore cows were divided into three groups (n=9 for each group) and their progeny as follows: UNS, unsupplemented during gestation; MID, supplemented from 30 to 180 days of gestation; LATE, supplemented from 181 to 281 days of gestation. The percentage composition of the supplement provided for the matrices was the following: ground corn (26.25%), wheat bran (26.25%) and soya bean meal (47.5%). The supplement was formulated to contain 30% CP. Supplemented matrices received 150 kg of supplement (1 and 1.5 kg/day for cows in the MID and LATE groups, respectively). After birth, a biopsy was performed to obtain samples of skeletal muscle tissue from calves to determine number and size of muscle fibres and for messenger RNA (mRNA) expression analysis. The percentage composition of the supplement provided for the progeny was the following: ground corn grain (30%), wheat bran (30%), soya bean meal (35%) and molasses (5%). The supplement was formulated to contain 25% CP and offered in an amount of 6 g/kg BW. Performance of the progeny was monitored throughout the suckling period. Means were submitted to ANOVA and regression, and UNS, MID and LATE periods of supplementation were compared. Differences were considered at P<0.10. Birth weight, average daily gain and weaning weight of the offspring did not differ among treatments (P>0.10). Similarly, no differences were observed between calves for nutrient intake (P>0.10). However, greater subcutaneous fat thickness (P=0.006) was observed in the calves of LATE group. The ribeye area (P=0.077) was greater in calves born from supplemented compared with UNS cows. The supplementation of pregnant cows did not affect the muscle fibre size of their progeny (P=0.208). On the other hand, calves born from dams supplemented at mid-gestation had greater muscle fibre number (P=0.093) compared with calves from UNS group. Greater mRNA expression of peroxysome proliferator-activated receptor α (P=0.073) and fibroblast growth factor 2 (P=0.003) was observed in the calves born from MID cows. Although strategic supplementation did not affect the BW of offspring, it did cause changes in carcass traits, number of myofibres, and mRNA expression of a muscle hypertrophy and lipid oxidation markers in skeletal muscle of the offspring.
Restoration of in situ fiber degradation and the role of fibrolytic microbes and ruminal pH in cows fed grain-rich diets transiently or continuously
- P. Pourazad, R. Khiaosa-ard, B. U. Metzler-Zebeli, F. Klevenhusen, Q. Zebeli
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- Published online by Cambridge University Press:
- 22 May 2017, pp. 2193-2202
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In this study, we used two different grain-rich feeding models (continuous or transient) to determine their effects on in situ fiber degradation and abundances of important rumen fibrolytic microbes in the rumen. The role of the magnitude of ruminal pH drop during grain feeding in the fiber degradation was also determined. The study was performed in eight rumen-fistulated dry cows. They were fed forage-only diet (baseline), and then challenged with a 60% concentrate diet for 4 weeks, either continuously (n=4 cows) or transiently (n=4 cows). The cows of transient feeding had 1 week off concentrate in between. Ruminal degradation of grass silage and fiber-rich hay was determined by the in situ technique, and microbial abundances attached to incubated samples were analyzed by quantitative PCR. The in situ trials were performed at the baseline and in the 1st and the last week of concentrate feeding in the continuous model. The in situ trials were done in cows of the transient model at the baseline and in the 1st week of the re-challenge with concentrate. In situ degradation of NDF and ADF of the forage samples, and microbial abundances were determined at 0, 4, 8, 24 and 48 h of the incubation. Ruminal pH and temperature during the incubation were recorded using indwelling pH sensors. Compared with the respective baseline, both grain-rich feeding models lowered ruminal pH and increased the duration of pH below 5.5 and 5.8. Results of the grass silage incubation showed that in the continuous model the extent of NDF and ADF degradation was lower in the 1st, but not in the last week compared with the baseline. For the transient model, degradation of NDF of the silage was lower during the re-challenge compared with the baseline. Degradation of NDF and ADF of the hay was suppressed by both feeding models compared with the respective baseline. Changes in fiber degradation of either grass silage or hay were not related to the magnitude of ruminal pH depression during grain-rich feeding. In both feeding models total fungal numbers and relative abundance of Butyrivibrio fibrisolvens attached to the incubated forages were decreased by the challenge. Overall, Fibrobacter succinogenes was more sensitive to the grain challenge compared with Ruminococcus albus and Ruminococcus flavefaciens. The study provided evidence for a restored ruminal fiber degradation after prolonged time of grain-rich feeding, however depending on physical and chemical characteristics of forages.
Effect of feeding long or short wheat hay v. wheat silage in the ration of lactating cows on intake, milk production and digestibility
- Y. Shaani, M. Nikbachat, E. Yosef, Y. Ben-Meir, I. Mizrahi, J. Miron
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- Published online by Cambridge University Press:
- 23 May 2017, pp. 2203-2210
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The objective of this study was to evaluate in lactating cows the effect of either chopping or ensiling of wheat roughage on: intake, digestibility, lactation performance and animal behavior. Three groups of 14 lactating cows each, were fed total mixed rations (TMRs) based on either long wheat hay (HL), short wheat hay (HS) or wheat silage (SI), as the sole roughage source (30% of TMR dry matter (DM)). Parameters examined: sorting behavior, DM intake, milk yield and composition, rumination, recumbence, average daily rumen pH, digesta passage rate, and in-vivo digestibility. Performance data was summarized by day and analyzed using a proc-mixed model. The content of physically effective neutral detergent fiber (peNDF) was similar in the HL and SI and lower in the HS, resulting in similar differences among the three corresponding TMRs. In vitro DM digestibility of wheat silage was higher than that of the two hays (65.6% v. 62.8%) resulting in higher in vitro DM digestibility of the SI-TMR compared with the hay-based TMRs (79.3 v. 77.0%). HS-TMR was better than HL- or SI-TMRs at preventing feed sorting by cows after 12 or 24 h eating of the diets. Cows fed HS-TMR consumed more DM and NDF but less peNDF than the other two groups. Average daily rumen pH was similar in the three groups, but daily rumination time was highest in the cows fed HS-TMR. Rumen retention time was longest in cows fed HL-TMR. DM digestibility in cows fed SI-TMR was higher than that of HS and HL groups (65.2%, 61.8% and 62.4%, respectively), but NDF digestibility was similar in the three treatments. The highest intake of digestible DM was observed in cows fed SI-TMR, HS cows were intermediate and HL cows were the lowest. Consequently, cows fed SI-TMR had higher yields of milk, 4% fat corrected milk and energy-corrected milk (47.1, 42.9 and 43.2 kg/day, respectively) than cows fed HS-TMR (45.7, 41.0 and 41.0 kg/day, respectively) or HL-TMR (44.1, 40.3 and 40.3 kg/day, respectively). Net energy production (NEL+M+gain) per kg DM intake was highest in the SI-TMR, lowest in the HS-TMR and intermediate in the HL-TMR (1.52, 1.40 and 1.45, respectively). Animal welfare, as expressed in daily recumbence time and BW gain was similar in the SI and HS groups and higher than the HL cows.
The effect of varying proportion and chop length of lucerne silage in a maize silage-based total mixed ration on diet digestibility and milk yield in dairy cattle
- A. L. Thomson, D. J. Humphries, A. K. Jones, C. K. Reynolds
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- Published online by Cambridge University Press:
- 27 June 2017, pp. 2211-2219
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The objective was to assess the effects of inclusion rate and chop length of lucerne silage, when fed in a total mixed ration (TMR), on milk yield, dry matter (DM) intake (DMI) and digestion in dairy cows. Diets were formulated to contain a 50 : 50 ratio of forage : concentrate (DM basis) and to be isonitrogenous (170 g/kg CP). The forage portion of the offered diets was comprised of maize and lucerne silage in proportions (DM basis) of either 25 : 75 (high Lucerne (HL)) or 75 : 25 (low lucerne (LL)). Lucerne was harvested and conserved as silage at either a long (L) or short (S) chop length. These variables were combined in a 2×2 factorial arrangement to give four treatments (HLL, HLS, LLL, LLS) which were fed in a Latin square design study to Holstein dairy cows in two separate experiments. In total, 16 and 8 multiparous, mid-lactation cows were used in experiments 1 and 2, respectively. To ensure sufficient silage for both experiments, different cuts of lucerne silage (taken from the same sward) were used for each experiment: first cut for experiment 1 (which was of poorer quality) and second cut for experiment 2. Dry matter intake, milk yield and milk composition where measured in both experiments, and total tract digestibility and nitrogen (N) balance were assessed using four cows in experiment 2. In experiment 1, cows fed LL had increased DMI (+3.2 kg/day), compared with those fed HL. In contrast, there was no difference in DMI due to lucerne silage inclusion rate in experiment 2. A reduction in milk yield was observed with the HL treatment in both experiment 1 and 2 (−3.0 and −2.9 kg/day, respectively). The HL diet had reduced digestibility of DM and organic matter (OM) (−3% and −4%, respectively), and also reduced the efficiency of intake N conversion into milk N (−4%). The S chop length increased total tract digestibility of DM and OM (both +4%), regardless of inclusion rate. Inclusion of lucerne silage at 25% of forage DM increased milk yield relative to 75% inclusion, but a S chop length partially mitigated adverse effects of HL on DMI and milk yield in experiment 1 and on DM digestibility in experiment 2.
Jugular-infused methionine, lysine and branched-chain amino acids does not improve milk production in Holstein cows experiencing heat stress
- K. R. Kassube, J. D. Kaufman, K. G. Pohler, J. W. McFadden, A. G. Ríus
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- Published online by Cambridge University Press:
- 18 May 2017, pp. 2220-2228
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Poor utilization of amino acids contributes to losses of milk protein yield in dairy cows exposed to heat stress (HS). Our objective was to test the effect of essential amino acids on milk production in lactating dairy cows exposed to short-term HS conditions. To achieve this objective, 12 multiparous, lactating Holstein cows were assigned to two environments (thermoneutral (THN) or HS) from days 1 to 14 in a split-plot type cross-over design. All cows received 0 g/day of essential amino acids from days 1 to 7 (negative control (NC)) followed by an intravenous infusion of l-methionine (12 g/day), l-lysine (21 g/day), l-leucine (35 g/day), l-isoleucine (15 g/day) and l-valine (15 g/day, methionine, lysine and branched-chain amino acids (ML+BCAA)) from days 8 to 14. The basal diet was composed of ryegrass silage and hay, and a concentrate mix. This diet supplied 44 g of methionine, 125 g of lysine, 167 g of leucine, 98 g of isoleucine and 109 g of valine per day to the small intestine of THN cows. Temperature–humidity index was maintained below 66 for the THN environment, whereas the index was maintained above 68, peaking at 76, for 14 continuous h/day for the HS environment. Heat stress conditioning increased the udder temperature from 37.0°C to 39.6°C. Cows that received the ML+BCAA treatment had greater p.m. rectal and vaginal temperatures (0.50°C and 0.40°C, respectively), and respiration rate (8 breaths/min) compared with those on the NC treatment and exposed to a HS environment. However, neither NC nor ML+BCAA affected rectal or vaginal temperatures and respiration rates in the THN environment. Compared with THN, the HS environment reduced dry matter intake (1.48 kg/day), milk yield (2.82 kg/day) and milk protein yield (0.11 kg/day). However, compared with NC, the ML+BCAA treatment increased milk protein percent by 0.07 points. For the THN environment, the ML+BCAA treatment increased concentrations of milk urea nitrogen. For the HS environment, the ML+BCAA treatment decreased plasma concentrations of arginine, ornithine and citrulline; however, differences were not observed for the THN environment. In summary, HS elicited expected changes in production; however, infusions of ML+BCAA failed to increase milk protein yield. Lower dry matter intake and greater heat load in response to ML+BCAA contributed to the lack of response in milk production in HS cows. The ML+BCAA treatment may have reduced the breakdown of muscle protein in heat-stressed cows.
Physiology and functional biology of systems
Review Article
Animal Board Invited Review: Sheep birth distribution in past herds: a review for prehistoric Europe (6th to 3rd millennia BC)
- M. Balasse, A. Tresset, A. Bălăşescu, E. Blaise, C. Tornero, H. Gandois, D. Fiorillo, É. Á. Nyerges, D. Frémondeau, E. Banffy, M. Ivanova
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- Published online by Cambridge University Press:
- 23 May 2017, pp. 2229-2236
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In temperate latitudes sheep have a seasonal reproductive behaviour, which imposes strong constraints on husbandry in terms of work organization and availability of animal products. During the last 50 years, researchers have focused on understanding the mechanisms driving small ruminants’ reproduction cycles and finding ways to control them. This characteristic is inherited from their wild ancestor. However, the history of its evolution over the 10 millennia that separates present day European sheep from their Near Eastern ancestors’ remains to be written. This perspective echoes archaeologists’ current attempts at reconstructing ancient pastoral societies’ socio-economical organization. Information related to birth seasonality may be retrieved directly from archaeological sheep teeth. The methodology consists of reconstructing the seasonal cycle record in sheep molars, through sequential analysis of the stable oxygen isotope composition (δ18O) of enamel. Because the timing of tooth development is fixed within a species, inter-individual variability in this parameter reflects birth seasonality. A review of the data obtained from 10 European archaeological sites dated from the 6th to the 3rd millennia BC is provided. The results demonstrate a restricted breeding season for sheep: births occurred over a period of 3 to 4 months, from late winter to early summer at latitudes 43°N to 48°N, while a later onset was observed at a higher latitude (59°N). All conclusions concurred with currently held expectations based on present day sheep physiology, which, aside from the historical significance, contributes to the reinforcing of the methodological basis of the approach. Further study in this area will permit regional variability attributable to technical choices, within global schemes, to be fully reported.
Review: Deciphering animal robustness. A synthesis to facilitate its use in livestock breeding and management
- N. C. Friggens, F. Blanc, D. P. Berry, L. Puillet
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- 02 May 2017, pp. 2237-2251
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As the environments in which livestock are reared become more variable, animal robustness becomes an increasingly valuable attribute. Consequently, there is increasing focus on managing and breeding for it. However, robustness is a difficult phenotype to properly characterise because it is a complex trait composed of multiple components, including dynamic elements such as the rates of response to, and recovery from, environmental perturbations. In this review, the following definition of robustness is used: the ability, in the face of environmental constraints, to carry on doing the various things that the animal needs to do to favour its future ability to reproduce. The different elements of this definition are discussed to provide a clearer understanding of the components of robustness. The implications for quantifying robustness are that there is no single measure of robustness but rather that it is the combination of multiple and interacting component mechanisms whose relative value is context dependent. This context encompasses both the prevailing environment and the prevailing selection pressure. One key issue for measuring robustness is to be clear on the use to which the robustness measurements will employed. If the purpose is to identify biomarkers that may be useful for molecular phenotyping or genotyping, the measurements should focus on the physiological mechanisms underlying robustness. However, if the purpose of measuring robustness is to quantify the extent to which animals can adapt to limiting conditions then the measurements should focus on the life functions, the trade-offs between them and the animal’s capacity to increase resource acquisition. The time-related aspect of robustness also has important implications. Single time-point measurements are of limited value because they do not permit measurement of responses to (and recovery from) environmental perturbations. The exception being single measurements of the accumulated consequence of a good (or bad) adaptive capacity, such as productive longevity and lifetime efficiency. In contrast, repeated measurements over time have a high potential for quantification of the animal’s ability to cope with environmental challenges. Thus, we should be able to quantify differences in adaptive capacity from the data that are increasingly becoming available with the deployment of automated monitoring technology on farm. The challenge for future management and breeding will be how to combine various proxy measures to obtain reliable estimates of robustness components in large populations. A key aspect for achieving this is to define phenotypes from consideration of their biological properties and not just from available measures.
Research Article
Season of birth is associated with first-lactation milk yield in Holstein Friesian cattle
- M. Van Eetvelde, M. M. Kamal, L. Vandaele, G. Opsomer
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- 24 May 2017, pp. 2252-2259
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The aim of the present research was to assess factors associated with first-lactation milk yield in dairy heifers, including maternal and environmental factors, factors related to the development of the heifer and factors related to its offspring such as gender of the calf. In addition, the potential underlying mechanism, in particular metabolic adaptations, was further explored. Data on body growth, reproduction and milk yield of 74 Holstein Friesian heifers on three herds in Flanders (Belgium) were collected. At birth, body measurements of the heifers were recorded and blood samples were taken (in order) to determine basal glucose and insulin concentrations. Body measurements were assessed every 3 months until first calving, and gender and weight of their first calf were recorded. Information on fertility and milk yield of the heifer and its dam were collected from the herd databases. Daily temperature and photoperiod were recorded from the database of the Belgian Royal Meteorological Institute. Linear mixed models were run with herd as a random factor, to account for differences in herd management. Heifers grew 867±80.7 g/day during their first year of life and were inseminated at 14.8±1.34 months. First calving took place at 24.5±1.93 months, at a weight of 642±61.5 kg and heifers produced 8506±1064 kg energy corrected milk during their first 305-day lactation. Regression models revealed that none of the maternal factors such as milk yield and parity, nor the growth of the heifer during the 1st year of life were associated with milk yield during first lactation. Age, and to a lesser extent BW at first parturition were positively associated with first-lactation milk yield. In addition, the season of birth, but not calving, had a significant influence on milk yield, with winter-born heifers producing less than heifers born in any other season. The lower yielding winter-born heifers had higher insulin concentrations at birth, whereas glucose concentrations were similar, the latter being suggestive for lower insulin sensitivity of the peripheral tissues. Furthermore, environmental temperature at the end of gestation was negatively correlated with neonatal insulin concentrations. In conclusion, results of the present study suggest heifers born during the hotter months are born with a higher peripheral insulin sensitivity, finally leading to a higher first-lactation milk yield.
Impacts of stocking density on development and puberty attainment of replacement beef heifers
- K. M. Schubach, R. F. Cooke, A. P. Brandão, K. D. Lippolis, L. G. T. Silva, R. S. Marques, D. W. Bohnert
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- 19 May 2017, pp. 2260-2267
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In all, 60 Angus×Hereford heifers were ranked by age and BW (210±2 days and 220±2 kg) on day 0, and assigned to: (a) one of three drylot pens (10×14 m pens; 10 heifers/pen) resulting in a stocking density of 14 m2/heifer (HIDENS; n=3), or (b) one of three pastures (25 ha pastures; 10 heifers/pasture), resulting in a stocking density of 25 000 m2/heifer (LOWDENS; n=3). Pastures were harvested for hay before the beginning of this experiment, and negligible forage was available for grazing to LOWDENS heifers during the experiment (days 0 to 182). All heifers received the same limited-fed diet, which averaged (dry matter basis) 4.0 kg/heifer daily of hay and 3.0 kg/heifer daily of a corn-based concentrate. Heifer shrunk BW was recorded after 16 h of feed and water withdrawal on days −3 and 183 for BW gain calculation. On day 0, heifers were fitted with a pedometer behind their right shoulder. Each week, pedometer results were recorded and blood samples were collected for puberty evaluation via plasma progesterone. Plasma samples collected on days 0, 28, 56, 84, 112, 140, 161 and 182 were also analyzed for cortisol concentrations. On days 0, 49, 98, 147 and 182, hair samples were collected from the tail switch for analysis of hair cortisol concentrations. On days 28, 102 and 175, blood samples were collected for whole blood RNA isolation and analysis of heat shock protein (HSP) 70 and HSP72 mRNA expression. Heifers from LOWDENS had more (P<0.01) steps/week compared with HIDENS. No treatment effects were detected (P=0.82) for heifer BW gain. Plasma cortisol concentrations were greater (P⩽0.05) in LOWDENS compared with HIDENS heifers on days 84, 140, 161 and 182 (treatment×day interaction; P<0.01). Hair cortisol concentrations were greater (P<0.01) in HIDENS compared with LOWDENS heifers beginning on day 98 (treatment×day interaction; P<0.01). Heifers from LOWDENS had greater (P=0.04) mean mRNA expression of HSP72, and tended (P=0.09) to have greater mean mRNA expression of HSP70 compared with HIDENS. Heifers from HIDENS experienced delayed puberty attainment and had less (P<0.01) proportion of pubertal heifers on day 182 compared with LOWDENS (treatment×day interaction; P<0.01). In summary, HIDENS altered heifer stress-related and physiological responses, and delayed puberty attainment compared with LOWDENS.
MicroRNA-499-5p regulates porcine myofiber specification by controlling Sox6 expression
- X. Y. Wang, X. L. Chen, Z. Q. Huang, D. W. Chen, B. Yu, J. He, J. Q. Luo, Y. H. Luo, H. Chen, P. Zheng, J. Yu
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- 11 May 2017, pp. 2268-2274
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MicroRNAs (miRNAs) are a class of small non-coding RNAs that negatively regulate gene expression of target messenger RNAs (mRNAs) and miRNAs have been proven to play vital roles in skeletal muscle development. The miRNA-499-5p has been reported to be negatively related with the expression of Sox6, a critical transcription factor for the maintenance of fast-twitch skeletal muscle. In this study, we amplified a length of 2012-bp mRNA that contains a 1512-bp porcine Sox6 (pSox6) 3'UTR from skeletal muscle of a Duroc×Landrace×Yorkshire pig. By luciferase reporter assay we verified that pSox6 is a target of miR-499-5p. In extensor digitorum longus and Soleus muscles of pigs, the expression levels of miR-499-5p and pSox6 mRNA were also inversely correlated. Besides, overexpression of miR-499-5p in porcine satellite cells promoted the expression of MyHC I and MyHC IIa mRNA, along with a reduction of pSox6 mRNA. Taken together, these results indicate that miR-499-5p may facilitate the oxidative myofibers formation by downregulating pSox6 expression.
Behaviour, welfare and health
Research Article
A multiparametric approach to discriminate the impacts of different degrees of invasiveness of surgical procedures in sheep
- M. Faure, V. Paulmier, A. Boissy, A. de La Foye, A. de Boyer Des Roches, D. Durand
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- 04 May 2017, pp. 2275-2284
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Traumatic situations in animals induce responses including pain, expressed through behavioural and physiological pathways such as inflammation, oxidative stress, hypothalamic–pituitary–adrenal (HPA) axis and autonomic nervous system. As some of these systems can also be activated during excitement and situations with a positive valence, their use as a means to assess pain response is difficult. We explored (i) how these five aforementioned pathways change in sheep exposed to various degrees of invasiveness of surgical procedures despite a therapeutic regimen and (ii) whether a multiparametric analysis that combines information from these five pathways enhances the discrimination between these situations, and estimates the relative importance of these pathways in the response. We used 24 adult sheep split into four treatments: Control (C; no fasting, no anaesthesia, no surgery), Sham (S; fasting, anaesthesia, no surgery), Rumen Canulation (R; fasting, anaesthesia, rumen cannulation) and Rumen–Duodenal–Ileum cannulation (RDI; fasting, anaesthesia, cannulation of the rumen, duodenum and ileum). Sheep’ responses were measured for 5 days after surgery. When considering each behavioural or physiological pathway independently, discrimination between treatments was acceptable, its sensitivity (Se) ranging from 0% to 100%, and its specificity (Sp) ranging from 62% to 100%. The multiparametric analysis gathering information from the five pathways enhanced the effectiveness of discrimination between treatments (Se, 50% to 100%; Sp, 82% to 100%), and gave additional information on the relative contribution of each pathway to the global sheep response. Sheep global response was higher when exposed to a surgery, and increased with the surgery invasiveness. This response relied mostly on inflammation (absolute correlation for haptoglobin, 0.89), HPA (cortisol, 0.85) and behaviour (antalgic postures, 0.85). The multiparametric approach seems to be a promising tool to discriminate between different degrees of invasiveness of surgical procedures.