The effect of offering an energy and protein supplement to grazing Canchim beef cows either postpartum or both pre- and postpartum on lipid blood metabolites and folliculogenesis.

This study was designed to evaluate the effect of nutritional supplementation offered during the pre- and postpartum periods on serum cholesterol, triglycerides and total lipids of Canchim beef cows and their relationship with folliculogenesis. Thirty cows with predicted calving date between September and October, kept in pastures of Brachiaria brizantha cv. Marandú together with their calves, were randomly distributed into three experimental groups: the first received only a mineral mixture (Control Group, CG); the second group received a concentrate with 16%crude protein/kg dry matter (DM) and 3000 kcal digestible energy/kg DM offered for 45 days prepartum and 120 days postpartum (PREG); the third group received the concentrate from parturition until the 120th day postpartum (POSG). Consumption was estimated at 1% of body weight, and each cow received approximately 4.0 kg/day (fresh weight) of supplement. Blood samples were taken and an ultrasound examination of the ovaries was performed twice a week until the 60th day postpartum. The body condition score (BCS) and the weight of the cows were recorded at 15-day intervals from calving until the 60th day postpartum. Data are presented as mean+/-SEM. Mean weight and BCS at calving were, respectively, 448+/-54.9 kg and 6.2+/-0.25 (PREG); 432+/-71.1 kg and 5.5+/-0.69 (POSG); and 434+/-66.4 kg and 5.5+/-0.69 (CG). Total cholesterol (TC), triglycerides (TRIG) and total lipids (TLIP) were measured using colorimetry until the 60th day postpartum. TC averages were PREG 186+/-62.6 mg/dL, POSG 159+/-43.1mg/dL and CG 133+/-35.1mg/dL (P<0.05). For TRIG, the means were PREG 29+/-11.3mg/dL (P<0.05), POSG 24+/-8.1mg/dL and CG 26+/-12.1mg/dL (P>0.05). Serum concentrations of TLIP were PREG 588+/-145.6 mg/dL, POSG 512+/-137.6 mg/dL and CG 452+/-122.4 mg/dL (P<0.05). The first dominant follicle (DF) was identified on Day 21+/-10.3 (PREG), 36+/-28.5 (POSG) and 51+/-32.8 (CG) after calving. The difference between PREG and CG was significant (P<0.05). TC was positively correlated with the calving to first estrus interval (P<0.05). Results showed that nutritional supplementation before parturition assured good body condition at calving and suggested that it was effective at increasing cholesterol availability to maintain ovarian follicle function and to favor earlier resumption of ovarian activity.

Effects of biostimulation and nutritional supplementation on pubertal age and pregnancy rates of Nelore heifers (Bos indicus) in a tropical environment.

To determine effects of biostimulation (BIO) and dietary supplementation (BIO+S) on pubertal age and pregnancy rates, Nelore heifers (n=392) were randomly assigned to one of four treatment groups (n=98/group). All animals were in tropical environmental conditions, in the middle-west region of Brazil, grazing in pastures of Brachiaria brizantha, cv. Marandu; Panicum Maximum, cv. Tanzânia and Brachiaria humidícula. The heifers of the BIO group were kept in the presence of bulls while being maintained on pasture; the animals in the BIO+S group were kept in the presence of bulls while being managed on pasture and were fed a diet with greater energy and protein content to produce 0.49 kg of BW gain/day; the animals in control group (the NBIO) were kept away from bulls and under pasture conditions; and the animals in the NBIO+S group were kept away from bulls, were maintained on pasture, and were fed the same diet as the BIO+S group. Heifers were bred at 22-23 months of age, and pregnancy diagnosis was made 45 days after the end of the breeding season. There were differences (P<0.05) between groups regarding pubertal heifers up to 19 months (NPH), final body weight (FBW) and pregnancy rates (P<0.01), with an advantage for the animals in the BIO and BIO+S groups. Although the effect of a diet with greater protein and energy content was not clear in this experiment, the exposure of heifers to a male during the prepubertal period decreased age at the first breeding season, resulting in a significant reduction in age of first pregnancy in Nelore heifers kept under extensive management systems in a tropical environment.