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Effects of feeding treatment on growth rates, metabolic profiles and age at puberty, and their relationships in dairy heifers
- F. Abeni, F. Petrera, Y. Le Cozler
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Puberty attainment in dairy heifers has been widely studied from a hormonal point of view, but few studies have focussed on puberty–blood profile relationships during growth. We led experiments to determine the effects of feeding treatments on growth parameters, age at puberty and plasma biochemical profiles, and the relationships between age at puberty and metabolic profiles at 6, 9, 12 and 15 months (mo) of age. Blood samples were collected from 67 Holstein heifers, born between September 2011 and February 2012, every 10 days from 5.5 mo of age until heifers were considered pubertal (plasma progesterone concentration greater than 1.0 ng/ml) or oestrus synchronisation (November 2012; 11 to 15 mo of age). Heifers born before 30 November were fed either a standard diet (SD, n=27) or an intensive-plane diet (ID1, n=27) from 0 to 6 mo of age. This strategy aimed to reach 190 to 200 kg (SD) or 220 to 230 kg (ID1) BW at 6 mo of age. All heifers born after 1 December received an intensive-plane diet (ID2, n=13) from birth until oestrus synchronisation, in order to reach a similar BW at first insemination as heifers born before 1 December. Only 56 heifers reached puberty before oestrus synchronisation, at an average age of 10.3±2.2 mo (6.2 to 14.4 mo) and a BW of 296±40 kg (224 to 369 kg). There was no difference among the three feeding treatments until 6 mo, but at 9, 12 and 15 mo of age, ID2 (n=11) heifers weighed 37, 52 and 30 kg more than SD (n=22) and ID1 (n=23) heifers (P<0.001), respectively. Glucose, non-esterified fatty acids, albumin, aspartate aminotransferase, alkaline phosphatase and tartrate-resistant acid phosphatase, calcium, phosphorus, potassium and iron decreased with age, whereas β-hydroxybutyric acid, total cholesterol, creatinine, the creatinine : albumin ratio, alanine aminotransferase and chloride increased. The feeding treatment significantly affected creatinine, the creatinine : albumin ratio, and phosphorus and sodium levels, which were higher for ID2 heifers compared with SD and ID1. A logistic regression based on plasma metabolites at 6 mo of age to explain puberty attainment before or at 12 mo of age showed a positive relationship with plasma cholesterol (odds ratio=9.05). In conclusion, the feeding treatment had minor consequences on plasma metabolites, but it did affect growth performance.
IgG1 variations in the colostrum of Holstein dairy cows
- Y. Le Cozler, R. Guatteo, E. Le Dréan, H. Turban, F. Leboeuf, K. Pecceu, J. Guinard-Flament
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High-immune quality colostrum (IgG1 concentration ⩾50 g/l) is crucial for the health and development of the young calf. Studies on colostrum quality tend to focus on external factors such as breed, parity or dry period length, but few have focused on within-cow variations. Here we ran experiments to gain a deeper insight into within-cow variation in IgG1 concentrations in dairy cow colostrum. Trials were performed in an experimental farm, located in the Western part of France. Colostrum from each quarter and a composite sample (mix of four quarters) were concomitantly collected on 77 Holstein dairy cows just after calving to assess the influence of sample type on IgG1 concentrations. Variation in IgG1 concentrations during the first milking was studied on samples from nine cows collected every minute from the start of milking. Repeatability of colostral IgG1 concentration was estimated from 2009 and 2010 data on 16 healthy cows. IgG1 concentrations were tested using a radial immunodiffusion method. Sensitivity and specificity were similar regardless of sample type tested (individual quarter or composite milk). Mean average IgG1 concentration was 54.1 g/l in composite colostrum, and was significantly higher in hind quarter teats (56.2 g/l) than front quarter teats (53.1 g/l). Average IgG1 concentration did not change significantly during colostrum milking, and the variations observed (15% or less) were likely due to the laboratory method (CV 15%). IgG1 concentrations in dam colostrum increased slightly from 2009 to 2010 due to BW and parity effects. In 56% of cases, colostrum quality could have been assessed on either individual or composite colostrum samples collected at any time during the first milking without affecting the reliability of the measurement. However, in other cases, differences were significant enough to mean that estimates of average IgG1 concentration in colostrum from any one quarter would not be reliable. It is concluded that colostrum quality, from an IgG1 concentration point of view, could be assessed with a composite sample taken at any time during the first milking.
Non-parametric approaches to the impact of Holstein heifer growth from birth to insemination on their dairy performance at lactation one
- C. SAUDER, H. CARDOT, C. DISENHAUS, Y. LE COZLER
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- The Journal of Agricultural Science / Volume 151 / Issue 4 / August 2013
- Published online by Cambridge University Press:
- 20 December 2012, pp. 578-589
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Parametric approaches have been used widely to model animal growth and study the impact of growth profile on performance. Individual variation is often not considered in such approaches. However, non-parametric modelling allows this. Such an approach, based on spline functions, was used to study the importance of growth profiles from age 0 to 15 months (i.e. insemination) on milk yield and composition in primiparous cows. A dataset of 447 heifers was used for analysis of growth performance; 296 of them were also used to study impact on lactation. All of them originated from a French experimental herd and were born between 1986 and 2006. Clustering methods were also tested. Comparison of spline methods showed that a cubic spline interpolation method, with no smoothing parameter, was best suited to studying heifer growth. Similarly, partitioning around medoids proved the most accurate clustering method for classifying heifer growth into groups. The results of these analyses agreed with those previously published, supporting the utility of these methods. A final study on the impact of breakdowns in the growth curves was performed. A breakdown was considered only when the derivative of the interpolation function was negative or zero. Of the 447 heifers initially used, 125 (Gr0), 175 (Gr1) and 147 (Gr2) had no, one, or two or more breakpoints during the 0–15 months of age period. Milk yield on a 305 d basis was significantly reduced with an increased number of breakpoints (6548 v. 6828 and 6905 kg for Gr2, Gr1 and Gr0 animals, respectively). Fat content was also higher in Gr2 than in Gr0 groups, but overall, no difference in total fat or protein-corrected milk production was noted. The intersection between groups for growth and groups for breakdowns confirmed that animals with two or more breakdowns belonged more frequently to the group with the lowest growth performance. These results offer the possibility of analysing large databases, originating from an automatic collecting system (e.g. milking robots) or from different herds, breeds, genetics, etc. These approaches could also be used for studies on body score index, girth development, lactation profiles, etc. and in other species, such as dairy goats or beef cattle. They could find use in the development of new models of prediction, e.g. the probability of heat appearance on an animal basis, which could be included among useful management tools.
A survey on dairy heifer farm management practices in a Western-European plainland, the French Pays de la Loire region
- Y. LE COZLER, O. RECOURSÉ, E. GANCHE, D. GIRAUD, J. DANEL, M. BERTIN, P. BRUNSCHWIG
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- The Journal of Agricultural Science / Volume 150 / Issue 4 / August 2012
- Published online by Cambridge University Press:
- 16 February 2012, pp. 518-533
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Despite practical information and applied results from numerous experimental studies and/or field observations, there is a persistent gap between scientific recommendations and on-farm reality. There are numerous published reports on the impact of dairy heifer herd management conditions on short-term, medium-term and long-term performances, but few studies on actual dairy heifer herd management practices – particularly in France. In an attempt to address this shortfall, a survey was conducted in 2010 on 449 herds located in the second largest dairy production region, the Pays de la Loire region (Western France). Economic-related aspects of heifer farming were not addressed. The essentially qualitative survey information was collected by 107 independent agricultural technologists. A quantitative analysis based on a small set of the most representative key production criteria was also conducted on a representative sub-sample of 286 herds. Mean herd size, at 46·6 cows per farm, and milk production, at 7953 kg milk/cow/lactation, were close to French national averages (47·3 cows per farm and 8109 kg milk/cow/lactation). The survey covered nine core themes and confirmed an all-round lack of precise monitoring on animal growth, as reported in earlier studies performed outside France. Most of the farmers surveyed considered animal weight a useful indicator for estimating growth performance. However, very few actually weighed their animals, despite the fact that 0·80 of the farmers surveyed aimed to calve their heifers before 30 months of age, with 0·55 of them setting a minimum calving weight target of at least 610 kg. Mean calf age at weaning was 2·9 months, but in practice this was >3·5 months in 0·31 of cases. Although farmers differ on certain practices, common core foci emerged: weight or age targets for pre-determined growth and development stages (at weaning or at service), recycling non-marketable milk for feeding young calves, essentially visual oestrus detection methods, and others. Based on the farmers’ declarations, the estimated time spent rearing a heifer from birth to calving ranges from 12 to 15 h per animal, with most farmers spending an estimated 0–2 h/day rearing their heifers. While almost two-thirds of farmers stated that rearing heifers was a necessity, 0·36 of this survey population claimed they enjoyed the work, whereas 0·02 of the farmers felt the work was purely a chore. Mirroring the conclusions from other countries, dairy heifer herd performances could be improved through better animal monitoring and management.
Rearing strategy and optimizing first-calving targets in dairy heifers: a review
- Y. Le Cozler, V. Lollivier, P. Lacasse, C. Disenhaus
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Much research has been carried out and published on dairy replacement management, in order to rear heifers as efficiently as possible, from both a technical and economical point of view. In most cases, the aim is to rear the heifers at the lowest cost possible without any deleterious effects on future performances. However, the importance of dairy heifer husbandry is not sufficiently well recognized and probably mishandled by most farmers. The present review aims to give an actual overview of rearing procedures in dairy heifers and possible ways to achieve optimal goals. For many years, it has been well known that rapid rearing lowers the age of sexual maturity and consequently may be an efficient way to reduce the non-producing period prior to conception. But this may impair mammary development and consequently future milk production, at least during first lactation. In addition, a growth rate that is too low may not only be costly but also result in animals that are too fat at first calving, creating problems such as calving difficulties, dystocia, etc. Genetic considerations must also be factored, i.e. frame, size, body weight, etc. have changed during the last 20 years and there are differences between breeds. As a result, some time-honoured recommendations may not be appropriate. The present paper reviews factors and management practices that may affect rearing and subsequent performance of dairy heifers.