Towards a better understanding of the respective effects of milk yield and body condition dynamics on reproduction in Holstein dairy cows

The overall reproductive performance has decreased over the last decades, involving changes in cyclicity, oestrous behaviour and fertility. High milk yield (MY), low body condition score (BCS) and large body condition (BC) loss have been identified as risk factors. However, these effects are often confounded, as high MY and body lipid reserve mobilization are correlated. The aim of this study was to evaluate the respective effects of MY and BC on post-partum ovarian cyclicity, oestrus and fertility of Holstein cows. This study provides novel information, as MY and BC change were uncoupled in the overall dataset that included 98 lactations and milk progesterone profiles. Cows were assigned to two feeding-level groups: high feed, which achieved high MY and moderate BC loss throughout lactation (8410 kg, −1.17 unit from calving to nadir BCS), and low feed, which limited MY and triggered a large BC loss (5719 kg, −1.54 unit). MY and BC had different effects at different stages of the reproductive process. Cyclicity as well as non-fertilization and early embryo mortality were mainly driven by body lipid reserves, whereas oestrous behaviour and late embryo mortality were related to MY. The results point to possible uncoupling between cyclicity, oestrus and early and late embryo survival allowing compensation along the reproductive process and leading to similar final reproductive performance. In compact calving systems, which require high pregnancy rates within a short period, higher MY strategies appear unsuitable even where BCS is maintained, owing to depressed oestrous behaviour and probably increased late embryo mortality, which delays rebreeding. Similarly, strategies that compromise cyclicity and fertility by excessively low BCS are unsuitabl

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

Genetic analysis of atypical progesterone profiles in Holstein-Friesian cows from experimental research herds

AbstractThe objective of this study was to quantify the genetic variation in normal and atypical progesterone profiles and investigate if this information could be useful in an improved genetic evaluation for fertility for dairy cows. The phenotypes derived from normal profiles included cycle length traits, including commencement of luteal activity (C-LA), interluteal interval, luteal phase length. and interovulatory interval. In total, 44,977 progesterone test-day records were available from 1,612 lactations on 1,122 primiparous and multiparous Holstein-Friesian cows from Ireland, the Netherlands, Sweden, and the United Kingdom. The atypical progesterone profiles studied were delayed cyclicity, prolonged luteal phase, and cessation of cyclicity. Variance components for the atypical progesterone profiles were estimated using a sire linear mixed model, whereas an animal linear mixed model was used to estimate variance components for the cycle length traits. Heritability was moderate for delayed cyclicity (0.24±0.05) and C-LA (0.18±0.04) but low for prolonged luteal phase (0.02±0.04), luteal phase length (0.08±0.05), interluteal interval (0.08±0.14), and interovulatory interval (0.03±0.04). No genetic variation was detected for cessation of cyclicity. Commencement of luteal activity, luteal phase length, and interovulatory interval were moderately to strongly genetically correlated with days from calving to first service (0.35±0.12, 0.25±0.14, and 0.76±0.24, respectively). Delayed cyclicity and C-LA are traits that can be important in both genetic evaluations and management of fertility to detect (earlier) cows at risk of compromised fertility. Delayed cyclicity and C-LA were both strongly genetically correlated with milk yield in early lactation (0.57±0.14 and 0.45±0.09, respectively), which may imply deterioration in these traits with selection for greater milk yield without cognizance of other traits

Projekt "Weidekuh-Genetik": Produktion, Fruchtbarkeit und Gesundheit

Ziel dieses Versuchs war es, die Schweizer Milchkuhrassen Holstein-Friesian (CH HF), Fleckvieh (CH FV) und Brown Swiss (CH BS) in Weidesystemen mit Blockabkalbung Ende Winter hinsichtlich Produktions-, Fruchtbarkeitsund Gesundheitsleistungen mit neuseeländischen Holstein-Friesian (NZ HF) zu vergleichen, die als Referenz für diesen Systemtyp gewählt wurden. Von 2007 bis 2009 wurden auf 15 Praxisbetrieben NZ HF Kühe Schweizer Kühen gegenübergestellt, wobei der Versuch insgesamt 259 Laktationen und 134 Kühe beinhaltete. Die CH HF und NZ HF wiesen die besseren Milchleistungen auf als die CH FV und CH BS (50,2 und 52,1 kg ECM / kg LG0,75 gegen 44,3 und 43,6 kg; P < 0,05). Der Anteil der nach sechs Wochen Besamungssaison trächtigen CH FV war tendenziell höher als bei den CH HF (81 % gegen 46% P < 0,10), die Rassen NZ HF und CH BS lagen dazwischen (66 % und 64 %). Die CH HF Kühe verfügen heute über ungenügende Fruchtbarkeitsleistungen für Systeme mit Blockabkalbung. Die Zweinutzungsrasse CH FV ist zwar weniger effizient in der Milchproduktion, scheint aber durch ihre guten Fruchtbarkeitsleistungen für diese Systeme geeignet zu sei

Projet "Quelle vache pour la pâture?": Production, reproduction et santé

L'objectif de cette étude était de comparer, en systèmes pâturants avec vêlages groupés de fin d'hiver, les performances de production, de reproduction et de santé de vaches laitières suisses de races Holstein (CH HF), Fleckvieh (CH FV) et Brown Swiss (CH BS) à des Holstein- Friesian d'origine néo-zélandaise (NZ HF) prises comme référence pour ce type de système. De 2007 à 2009, des vaches NZ HF ont été appariéesavec des vaches suisses sur 15 fermes commerciales, incluant au final 259 lactations de 134 vaches. Les vaches CH HF et NZ HF ont eu des meilleures performances laitières que les CH FV et CH BS (50,2 et 52,1 kg ECM / kg PV0,75 contre 44,3 et 43,6 kg; P < 0,05). La proportionde vaches CH FV gestantes en 6 semaines de reproduction était tendanciellement plus élevée que pour les vaches CH HF (81 % contre 46 %, P < 0,10), NZ HF et CH BS étant intermédiaires (66 et 64 %). Les vaches CH HF présentent aujourd'hui des performances de reproduction insuffisantes pour les systèmes en vêlages groupés. Inversement, les vaches mixtes CH FV sont moins efficaces en termes de production laitière mais apparaissent adaptées à ces systèmes de par leurs bonnes performances de reproduction

Feeding strategies and feed self-sufficiency of dairy farms in the lowland and mountain area of Western Switzerland

The feeding strategy and the feed self-sufficiency of 34 commercial dairy farms in the western part of Switzerland were investigated throughout the year 2010. Feed ration composition of farms from the lowlands with relatively high proportions of maize were compared to farms from the mountain area with relatively high proportions of herbage in the rations. Dairy feeds were categorized into herbage, whole-plant maize and concentrate. The proportions of dry matter (DM), net energy for lactation (NEL) and metabolizable protein (MP) sourced from herbage, maize and concentrates were calculated. Dairy farms located in the mountain area had higher proportions of herbage DM in the ration than farms located in the lowland (70% vs. 51 %), as well as herbage-sourced NEL (66 % vs. 47%) and herbage-sourced MP (68% vs. 49%). In contrast, lowland farms showed a higher proportion of maize DM in the ration (31% vs. 17 %). The degree of self-sufficiency of the total feed ration of mountain farms was shown to be larger for DM, NEL and especially MP. A general negative relationship between the proportion of maize DM in the ration and the dairy herd MP self-sufficiency could be observed

Feeding strategies and feed self-sufficiency of dairy farms in the lowland and mountain area of Western Switzerland

The feeding strategy and the feed self-sufficiency of 34 commercial dairy farms in the western part of Switzerland were investigated throughout the year 2010. Feed ration composition of farms from the lowlands with relatively high proportions of maize were compared to farms from the mountain area with relatively high proportions of herbage in the rations. Dairy feeds were categorized into herbage, whole-plant maize and concentrate. The proportions of dry matter (DM), net energy for lactation (NEL) and metabolizable protein (MP) sourced from herbage, maize and concentrates were calculated. Dairy farms located in the mountain area had higher proportions of herbage DM in the ration than farms located in the lowland (70% vs. 51 %), as well as herbage-sourced NEL (66 % vs. 47%) and herbage-sourced MP (68% vs. 49%). In contrast, lowland farms showed a higher proportion of maize DM in the ration (31% vs. 17 %). The degree of self-sufficiency of the total feed ration of mountain farms was shown to be larger for DM, NEL and especially MP. A general negative relationship between the proportion of maize DM in the ration and the dairy herd MP self-sufficiency could be observed

Projet "Quelle vache pour la pâture?": Synthèse et perspectives

L'essai visait à comparer les performances de vaches de races suisses Holstein, Swiss Fleckvieh et Brown Swiss à des Holstein-Friesian néo-zélandaises, sur des exploitations pratiquant la pâture intégrale avec vêlages saisonniers de fin d'hiver. Les deux types Holstein ont présenté les meilleures performances laitières et les Swiss Fleckvieh de l'essai une reproduction optimale. Laitières efficaces, même en systèmes bas-intrants, les Holstein suisses devraient présenter de meilleures performances de reproduction pour des vêlages groupés, même si nos simulations suggèrent que la production laitière a plus d'influence que la reproduction ou la performance carnée sur les performances économiques, ce qui confère un avantage aux deux types Holstein, les plus laitiers. Nos références économiques restent cependant à affiner pour ces systèmes spécifiques. Le choix des systèmes de production et le choix d'animaux efficaces dans ces systèmes reste un vaste domaine de recherche, en évolution constante. L'efficacité d'un animal dépend du système dans lequel il se trouve et la définition même de «l'efficacité d'utilisation des ressources» évolue avec nos connaissances en biologie, nutrition humaine, climatologie ou écologie

Projekt "Weidekuh-Genetik": Produktion, Zusammenfassung und Perspektiven

Der Versuch hatte zum Ziel, die Schweizer Rassen Holstein, Fleckvieh und Brown Swiss mit derjenigen neuseeländischer Holstein- Friesian auf Vollweidebetrieben mit saisonaler Abkalbung Ende Winter zu vergleichen. Die zwei Holsteintypen wiesen die besseren Milchleistungen auf, die Schweizer Fleckvieh des Versuchs dagegen eine optimale Fruchtbarkeit. Die Schweizer Holstein ist auch in Low-Input-Systemen eine effiziente Milchkuh, sie müsste jedoch für Blockabkalbung bessere Fruchtbarkeitsleistungen aufweisen, obwohl unsere Modellrechnungen allerdings darauf hin deuten, dass die Milchproduktion einen grösseren Einfluss als die Fruchtbarkeit oder die Fleischleistung hat, was hier den zwei milchbetonteren Holsteintypen einen wirtschaftlichen Vorteil verschafft. Die erhobenen Datensätze für diese spezifische Systeme müssen jedoch vervollständigt werden. Die Wahl von Produktionssystemen und effizienten Tieren für diese Systeme bleibt ein grosses und sich weiter entwickelndes Forschungsfeld. Die Effizienz eines Tieres hängt vom System ab und die Definition t der «Ressourcen- Effizienz» selbst entwickelt sich mit den wissenschaftlichen Fortschritten in der Tierproduktion, der menschlichen Ernährung, der Klimatologie und Ökologie weiter