Associations between genetic merit for milk production and animal parameters and the fertility performance of dairy cows

To simulate the consequences of management in dairy herds, the use of individual-based herd models is very useful and has become common. Reproduction is a key driver of milk production and herd dynamics, whose influence has been magnified by the decrease in reproductive performance over the last decades. Moreover, feeding management influences milk yield (MY) and body reserves, which in turn influence reproductive performance. Therefore, our objective was to build an up-to-date animal reproduction model sensitive to both MY and body condition score (BCS). A dynamic and stochastic individual reproduction model was built mainly from data of a single recent long-term experiment. This model covers the whole reproductive process and is composed of a succession of discrete stochastic events, mainly calving, ovulations, conception and embryonic loss. Each reproductive step is sensitive to MY or BCS levels or changes. The model takes into account recent evolutions of reproductive performance, particularly concerning calving-to-first ovulation interval, cyclicity (normal cycle length, prevalence of prolonged luteal phase), oestrus expression and pregnancy (conception, early and late embryonic loss). A sensitivity analysis of the model to MY and BCS at calving was performed. The simulated performance was compared with observed data from the database used to build the model and from the bibliography to validate the model. Despite comprising a whole series of reproductive steps, the model made it possible to simulate realistic global reproduction outputs. It was able to well simulate the overall reproductive performance observed in farms in terms of both success rate (recalving rate) and reproduction delays (calving interval). This model has the purpose to be integrated in herd simulation models to usefully test the impact of management strategies on herd reproductive performance, and thus on calving patterns and culling rates.Keywords: dairy cow, reproduction, model, milk yield, body condition score Implications This paper describes an up-to-date stochastic reproduction model of Holstein dairy cows. This model is sensitive to both milk production and body reserves and takes into account the recent evolutions of reproductive performance in dairy cows. This model is able to well simulate the overall reproductive performance observed in commercial farms. Therefore, it can be used in dynamic individual-based herd simulation models to anticipate the consequences of management strategies (in terms of reproduction or feeding) on dairy herd demography and global performance.

Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 91%

An individual reproduction model sensitive to milk yield and body condition in Holstein dairy cows

Brun-Lafleur

Cutullic

Faverdin

et al. 2013

“…The practice of once-daily milking limits the expression of milk production potential and the mobilization of reserves without degrading the intake capacity, and has a comparatively favourable impact on reproduction performance (Ré mond and Pomiè s, 2005). Finally, the rates of success at AI are rather better in cows that do not express their milk production potential (Mackey et al, 2007) because of insufficient body condition at calving or a lack of feed allocation early in lactation (this study). It is important to improve our understanding of the complex relationship between body condition score at calving, the level of nutritive supply at the beginning of lactation and the expressed milk production potential, as well as the effects on the functions of 'lactation' and 'reproduction'.…”

Section: Discussionmentioning

confidence: 75%

“…However, the success of this aggressive genetic selection for production, predominantly within the North American Holstein Friesian genotype, has resulted in increased incidence of nutritional and metabolic problems at the beginning of lactation. More generally, these developments in selection have increased feed requirements of high genetic potential animals throughout their lactation, and resulted in a clear deterioration in other functions such as the capacity to reproduce (Barbat et al, 2005;Mackey et al, 2007). By contrast, dual-purpose breeds and animals selected on multiple criteria are characterized by lower milk production potential while preserving other zootechnical capacities.…”

Section: Introductionmentioning

confidence: 99%

Effect of different feeding strategies on lactation performance of Holstein and Normande dairy cows

Delaby

Faverdin

Michel

et al. 2009

The dairy farming systems of Western Europe are based on a simple feeding system composed of grazed and preserved grass, maize silage and concentrates in variable proportions. There is, nevertheless, a great diversity of feeding strategies between dairy farms. Over 5 years, we studied the direct and delayed effects of four feeding strategies on the lactation and reproduction performances of Holstein and Normande dairy cows. The four feeding strategies (denoted Hh, Hl, Lh and Ll) correspond to two total mixed rations applied in winter from calving to turnout (maize silage with 30% concentrate or grass silage with 15% concentrate), which were subsequently crossed with two levels of concentrate supplementation at grazing to 210 days. Each year, 72 dairy cows managed in grouped winter calving were assigned to the four strategies. Finally, the results of 325 lactations and 295 inseminated cows were analysed. The four strategies resulted in considerable variation in nutrient intake and, in particular, in differences in concentrates consumed, with values of 1407, 1026, 773 and 392 kg dry matter per cow for strategies Hh, Lh, Hl and Ll, respectively. Total milk production (7567, 7015, 6720 and 6238 kg per cow for treatments Hh, Lh, Hl and Ll, respectively), milk fat content (39.0, 37.1, 40.3 and 38.5 g/kg, respectively), milk protein content (33.0, 31.8, 33.1 and 31.6 g/kg, respectively), and the character of the lactation and body condition curves were all highly sensitive to the strategies applied. While no significant interaction was detected on total lactation yield, the Holstein cows reacted more dramatically to each dietary change at each period, compared with the Normande cows. Winter feeding did not affect the production of milk at pasture whereas, at pasture, the milk from the cows of the H groups in winter was higher in milk fat and protein content. Reproduction performance was unaffected by feeding strategy. The Holstein cows, well fed and producing the most milk (Hh and Hb), had the lowest rate of success at first artificial inseminations (21.5%). The dual-purpose Normande cows had a pregnancy rate 10 points higher than Holstein cows. This comparison of strongly contrasting feeding strategies confirms the immediate reactivity of dairy cows (in terms of milk performance and body condition) to variations of nutritive intake throughout lactation, with a weak carryover effect from feeding levels early in lactation. In contrast, reproduction performance was less sensitive to variation in nutrient supply. Keywords: dairy cows, feeding strategy, lactation, reproduction, breed ImplicationsThe main objective of this 5-year experiment was to describe the dairy cows' ability to adapt their lactation and reproductive functions to different feeding strategies applied during lactation. These original results provide practical information on breed, feeding system effects and their interaction, and will help advisors and farmers to choose the most efficient systems according to the economic circumstances. IntroductionIn Fra...

“…Focusing on feeding management While dealing with impaired reproductive performance of dairy cows, genetic factors (Mackey et al, 2007), nutrition (Robinson et al, 2006), health of the cow (Collard et al, 2000) and work organisation (Zaaijer and Noordhuizen, 2003) are very often referred to. These four fields are closely connected together.…”

Section: Resarch Approaches On the Links Between Reproduction And Nutmentioning

confidence: 99%

Understanding the reproductive performance of a dairy cattle herd by using both analytical and systemic approaches: a case study based on a system experiment

Gouttenoire¹,

Fiorelli²,

Trommenschlager³

et al. 2010

Reproductive performance has recently been a growing concern in cattle dairy systems, but few research methodologies are available to address it as a complex problem in a livestock farming system. The aim of this paper is to propose a methodology that combines both systemic and analytical approaches in order to better understand and improve reproductive performance in a cattle dairy system. The first phase of our methodology consists in a systemic approach to build the terms of the problem. It results in formalising a set of potential risk factors relevant for the particular system under consideration. The second phase is based on an analytical approach that involves both analysing the shapes of the individual lactation curves and carrying out logistic regression procedures to study the links between reproductive performance and the previously identified potential risk factors. It makes it possible to formulate hypotheses about the biotechnical phenomena underpinning reproductive performance. The last phase is another systemic approach that aims at suggesting new practices to improve the situation. It pays particular attention to the consistency of those suggestions with the farmer's general objectives. This methodology was applied to a French system experiment based on an organic low-input grazing system. It finally suggested to slightly modify the dates of the breeding period so as to improve reproductive performance. The formulated hypotheses leading to this suggestion involved both the breed (Holstein or Montbé liarde cows), the parity, the year and the calving date with regard to the turnout date as the identified risk factors of impaired performance. Possible use of such a methodology in any commercial farm encountering a biotechnical problem is discussed.