Perfil metabólico e hormonal de vacas F1 Holandês-Zebu durante o pré e pós-parto e sua relação com a reprodução

Abstract

The aim of this study was evaluate mobilization of body reserves and metabolic and hormonal profile during transition period in crossbred Holstein Zebu cows, as well as measure milk production and composition and progesterone concentrations postpartum to indicate return to ovarian activity (active corpus luteum). Seventeen crossbred Holstein Zebu cows (parity three to eight; 4,130 kg milk/lactation), with calving date between June and July 2010, were used in this experiment. Blood samples were collected to measure glucose, insulin, NEFA and progesterone concentrations. Sampling was at days ten and five prepartum and two, five, ten, and then weekly postpartum until 60 days in milk (DIM). Weight and body condition score (BCS) were also recorded on the same days. Milk production measure and sampling for composition were performed weekly until 60 DIM. A randomized block design was utilized for statistical analysis, with analysis of variance and means tested with SNK (P=0.05). Milk production was 18.7 ± 3.6 kg/day (4.1% fat, 3.2% protein, 4.6% lactose, 12.8% total solids). Lowest weight and BCS occurred on day two postpartum. NEFA concentrations were highest between two and 17 days postpartum (0.484 ± 0.425 mmol/L), what shows this was the most intense period of negative energy balance. Lowest insulin concentration was observed in day five postpartum (6.6 ± 3.0 U/mL) (P<0.05) and highest glucose concentration at day two postpartum (66.1 ± 10.6 mg/dL) (P<0.05). After calving, progesterone concentrations were low until 38 DIM, when it reached 1.03 ± 0.77 ng/mL, indicating existence of functional corpus luteum.