Effect of the postpartum body reserve mobilization on the reproductive function in dairy cow

The body condition scoring technique (BCS) is used to evaluate body reserve s, their changes with respect to physiological stages and the energy balanc e of animals. The objective of this study was to evaluate the effect of the rate of body reserves mobilization after calving on the reproductive function in the pos tpartum dairy cow. The study was conducted on 216 Friesian and Holstein dai ry cows, belonging to 8 farms in the Temara-Skhirat province (northwest of Morocco). The body condition score (BCS) has been measured monthly for each cow, using a 1-9 scale. Milk samples have been collected once a week for e ach cow from newly calved cows until confirmation of pregnancy by rectal pa lpation, and this at least 2 month after an artificial insemination. These samples have been used to measure the levels of progesterone in skim milk. A diminution of the score of animals has been observed after calving indica ting a mobilization of their body reserves during this period; the most imp ortant diminution has been observed in cows of the farm F6, (20.5%), and th e less important diminution hi been observed in the farm F7, (9.0%). The la rgest intervals of calving to return to ovarian activity [C-ROA], calving t o first insemination [C-I1] and calving to conception [C-C] were observed i n the farm F6 (101.6 +/- 21.9 days; 112.3 +/- 21.5 days and 150.4 +/- 26.4 days respectively). The smallest [C-ROA] and [C-C] intervals were noted in the farm F7 (33.4 +/- 3.6 days and 89.8 +/- 4.7 days respectively). Signifi cant positive correlations were obtained between the duration of [C-ROA], [ C-I1] and [C-C] intervals and the degree of body reserve mobilization after calving (r = 0.88, p < 0.01; r = 0.74, p < 0.05; r = 0.85, p < 0.01 respec tively). In conclusion, it seems that the rate of body reserves mobilization after c alving has an effect on the reproductive function in the post-partum dairy cow.