Once-a-day milking of multiparous Holstein cows throughout the entire lactation: milk yield and composition, and nutritional status

Once-a-day milking of multiparous Holstein cows throughout the entire lactation: milk yield and composition, and nutritional status. Eighteen multiparous Holstein cows were distributed into two similar groups immediately after calving: the control group (M2) was milked twice a day throughout lactation whereas the other group (M1) was milked only once a day in the morning. During the indoor (winter) period, all animals received the same total mixed ration ad libitum. In the summer, they were turned to pasture at the same time. The seven cows of group M2 (2 cows were excluded) produced 7323 kg of milk on average in 305 days. The nine cows of group M1 produced 5114 kg of milk (–30%; P 0.10). Mean somatic cell count (log10 = 5.043 per mL and 4.946 per mL in groups M1 and M2, respectively) did not differ between the groups despite the sharp increase noted in group M1 during the last third of lactation. Casein and whey protein contents also were not significantly different between the groups. Plasmin and lipoprotein lipase activities were unchanged although the plasminogen-derived activity tended to be higher in the milk from group M1. The dry matter (feed) mean intake amount of the first 14 weeks of lactation did not differ between the two groups although it gradually became higher in the M2 group. Group M1 cows’ liveweight and body condition gradually improved over those of group M2, with a difference as high as 56 kg (P 0,10). Il en est de même des concentrations des cellules somatiques (log10 = 5,043 par mL et 4,946 par mL pour les lots 1M et 2M), malgré la forte augmentation observée dans le lot 1M au cours du dernier tiers de la lactation. La concentration des caséines et des protéines solubles n’a pas été significativement différente entre les lots. Les activités de la plasmine et de la lipoprotéine lipase n’ont pas été modifiées, mais l’activité dérivée du plasminogène a eu tendance à être plus élevée dans le lait du lot 1M. La quantité de matière sèche ingérée au cours des 14 premières semaines de lactation n’a pas été, en moyenne, différente entre les 2 lots, mais elle est progressivement devenue plus élevée dans le lot 2M. Le poids vif des vaches du lot 1M et leur état corporel sont progressivement devenus plus élevés que ceux du lot 2M, la différence atteignant 56 kg à la 36e semaine de lactation (P < 0,01) et 0,94 point de note d’état corporel (P = 0,02). Huit des neuf vaches du lot 1M et quatre des sept vaches du lot 2M ont été diagnostiquées fécondées. Les vaches du lot 1M n’ont présenté aucun trouble sanitaire particulier et aucun comportement anormal