Efecto de la grasa bypass sobre la reactivación ovárica postparto en vacas holstein friesian mestizas con condición corporal diferente

Abstract

The effect of bypass fat on productive and reproductive parameters in crossbred Holstein Friesian cows with different body condition (CC) was the objective of the study. Four treatments were analyzed: T1 (n=10) CC> 3.5 without fat bypass; T2 (n=10) CC> 3.5 with bypass grease; T3 (n=10) CC <2.5 without fat bypass and T4 (n=10) CC <2.5 with bypass fat. The CC and weight were evaluated on the 25th day before, at delivery and postpartum until day 65. Milk production was determined during the first two months of lactation. Ovarian reactivation was assessed by ultrasonography once a week. The first postpartum estrus (1CPP), preovulatory follicle (FPO), corpus luteum (CL) and progesterone levels (P4) at day 7 were evaluated. The first delivery interval (IPPS) and the number of inseminations per pregnancy (IA/P). Uterine health (SU) was determined at day 35 postpartum. A mixed linear model was used for the statistical analysis using the MIXED procedure. The T1 cows lost more CC than the other treatments (P <0.05); however, T2, T3 and T4 presented no difference (P> 0.05). Animals that received fat bypass (T2 and T4) lost less weight (P <0.05) compared to T1 and T3. T2 cows produced more milk (P <0.05) than T1, T3 and T4 animals. T2 presented less polymorph nuclear (8.12%), compared to T1, T3 and T4 (P <0.05). The number of IA/P used in T2 was lower (1.69) than T1, T3 and T4 (2.9, 2.5 and 2.5 respectively) (P <0.05). The CPI was reduced to 73.6 days in T2 and its P4 levels were higher (6.06 ng/ml), determining differences with the other treatments. The addition of fat bypass in the basal diet of lactating cows improved the productive and reproductive parameters.