Consequence on reproduction of two feeding levels with opposite effects on milk yield and body condition loss in Holstein and Normande cows

E. Cutullic , Luc Delaby , G. Michel , Catherine Disenhaus (1)

1 PL - Production du lait

The objective of this study was to evaluate the respective effects of milk yield and body condition (BC) loss on cows' postpartum reproductive status taking breed differences into account. 105 Normande (dual-purpose) and 98 Holstein cows were assigned to a low or high feeding level (L-group: 50% grass silage and 50% haylage in winter, no concentrate at grazing; H-group: 55% maize silage, 15% alfalfa hay and 30% concentrate, 4kg concentrate at grazing). Milk progesterone assays led to determine commencement of luteal activity (CLA), postpartum ovarian activity profile, ovulation detection rate and late embryo mortality. Data were analysed by variance-covariance and logistic regression models. In both breeds, L-group cows had a lower 100-day average daily milk yield (MY) than the H-group cows but lost more BC (0-5 scale) (21.5 vs. 30.9 kg/day, -1.38 vs. -0.94 unit, N=102 and 101; P<0.001). Feeding level effect on MY was greater for Holstein than for Normande cows (+10.9 vs. +8.0 kg/day; P<0.05). As expected, Normande cows had shorter CLA, less prolonged luteal phase cycles and higher calving rate than Holstein cows (P<0.01). Feeding level had little effect on CLA and ovarian activity profile. In both breeds, ovulation detection rate was higher in the L-group (77% vs. 60%, N= 254 and 282; P<0.001). At 1st and 2nd inseminations, conception rate was improved in the H-group (74% vs. 57%, N=125 and 138; P<0.01), especially for Holstein cows (73% vs. 48%; P<0.01). As late embryo mortality frequency was very high in the H-Group Holstein cows (30% vs. 9%, N= 64 and 64; P<0.01), difference in calving rate was not significant between feeding groups (P>0.25). Owing to feeding level effects, MY and BC loss could affect reproduction at different stages. Consistent with the literature, a greater BC loss coincides with reduced conception rate. High milk yield coincides with depressed ovulation detection and embryo survival.

Mots clés: reproduction; milk yield; body condition loss

Domaines: Science des productions animales

E. Cutullic, Luc Delaby, G. Michel, Catherine Disenhaus. Consequence on reproduction of two feeding levels with opposite effects on milk yield and body condition loss in Holstein and Normande cows. Journal of Dairy Science, 2009, 92 (E-Suppl.) 1, non paginé. ⟨hal-00730135⟩