Associations among BCS, milk production and days-open in Walloon primiparous dairy cows

Conference (2009, August 27)

OptiVal + Optimisation des Valorisations issues du Contrôle des Performances à travers le développement d’outils pratiques de management visant à augmenter la rentabilité de toutes les exploitations laitières wallonnes. Deuxième rapport intermédiaire, avril 2009.

Report (2009)

Modeling milk urea of Walloon dairy cows in management perspectives.

in Journal of Dairy Science (2009), 92(7), 3529-40

The aim of this study was to develop an adapted random regression test-day model for milk urea (MU) and to study the possibility of using predictions and solutions given by the model for management ... [more ▼]

The aim of this study was to develop an adapted random regression test-day model for milk urea (MU) and to study the possibility of using predictions and solutions given by the model for management purposes. Data included 607,416 MU test-day records of first-lactation cows from 632 dairy herds in the Walloon Region of Belgium. Several advanced features were used. First, to detect the herd influence, the classical herd x test-day effect was split into 3 new effects: a fixed herd x year effect, a fixed herd x month-period effect, and a random herd test-day effect. A fixed time period regression was added in the model to take into account the yearly oscillations of MU on a population scale. Moreover, first autoregressive processes were introduced and allowed us to consider the link between successive test-day records. The variance component estimation indicated that large variance was associated with the random herd x test-day effect (48% of the total variance), suggesting the strong influence of herd management on the MU level. The heritability estimate was 0.13. By comparing observed and predicted MU levels at both the individual and herd levels, target ranges for MU concentrations were defined to take into account features of each cow and each herd. At the cow level, an MU record was considered as deviant if it was <200 or >400 mg/L (target range used in the field) and if the prediction error was >50 mg/L (indicating a significant deviation from the expected level). Approximately 7.5% of the MU records collected between June 2007 and May 2008 were beyond these thresholds. This combination allowed for the detection of potentially suspicious cows. At the herd level, the expected MU level was considered as the sum of the solutions for specific herd effects. A herd was considered as deviant from its target range when the prediction error was greater than the standard deviation of MU averaged by herd test day. Results showed that 6.7% of the herd test-day MU levels between June 2007 and May 2008 were considered deviant. These deviations seemed to occur more often during the grazing period. Although theoretical considerations developed in this study should be validated in the field, this research showed the potential use of a test-day model for analyzing functional traits to advise dairy farmers. [less ▲]

Le BCS, une méthode simple à la source de conseils variés : ration, repro et santé

in 14ième Carrefour des Productions animales: Les filières bovines dans la tourmente, Produire plus et mieux avec moins: Gembloux, le 11 février 2009 (2009)

Développement d’un outil de prédiction de la probabilité de réussite à l’insémination chez la vache laitière à partir des données du Contrôle Laitier

in 15ème Rencontres Recherches Ruminants, Paris, les 3 et 4 décembre 2008 (2008, December)

Alternative modelling of body condition score from Walloon Holstein cows to develop management tools

Conference (2008, June)

OptiVal: Vers de nouveaux outils de gestion pour les éleveurs laitiers wallons, Prédire la réussite à l’insémination

Poster (2008, January 23)

Predicting bovine milk urea concentration for future test-day records in a management perspective

in Proceedings of the British Society of Animal Science (2008)

Alternative modelling of body condition score from Walloon Holstein cows to develop management tools

in Proceedings ICAR 36th Session (2008)

First steps to model milk urea in a management perspective

Conference (2007, July)