Efeito de diferentes protocolos de suplementação de colina protegida em vacas leiteiras durante o período de transição

Abstract

The transition period is the most critical phase of the dairy production system. The large drop in dry matter intake peripartum and rising energy costs in early lactation result in negative energy balance (BEN). Dairy cows under BEN obtain energy from their fat reserves through mobilization of non-esterified fatty acids (NEFA). The elevation of this metabolite and its products in the bloodstream has drastic consequences to health, production and reproduction of dairy cows. The search for strategies to reduce this imbalance and improve the transition cow performance is a challenge to producers and experts in the field. Thus, the aim of this study was to evaluate the effect of the choline protected in production, uterine health, metabolism and reproduction in cows during the transition period with different supplementation times. In the first study were used 15 cows in the transition period. The treated group was supplemented with 80 grams of choline protected for 21 days before calving to 40 days. Blood samples were collected on days 21 and 10 before delivery and on days 10, 20 and 30 for postpartum evaluation of metabolic, liver and oxidative profile. The supplementation with choline did not change the fructosamine, cholesterol, NEFA hydroxybutyrate beta (BHB), growth factor similar to insulin (IGF-I), aspartate aminotransferase (AST), gamma glutamyltransferase (GGT) and total oxidants (TOS) levels. Weighing of milk was performed on days 10, 20 and 30 of lactation, and no treatment effect on production. At 60 days postpartum was conducted gynecological examination. After 60 days, the control group had more cases of endometritis, but no effect of treatment on the calving interval. Progesterone levels were larger in the control group than in the group treated at 60 days postpartum. Choline supplementation so it did not change the metabolic profile, but reduced the number of cases of endometritis at 60 days postpartum. In second study were used 54 cows, divided into three groups: control, cows supplemented by 10 antepartum days with protected choline (T10) and cows supplemented by 20 antepartum days with protected choline (T20). Blood samples were collected on days 10, 20 and 30 postpartum for determination of fructosamine, cholesterol, NEFA, BHB, AST, GGT and TOS levels. There was no difference between groups for any of the blood parameters. Milk production was evaluated on days 10, 20 and 30 of lactation, with no effect of treatments on the volume of milk produced. The interval between delivery and conception was lower in animals T20 group than the other groups. The protected choline did not change the metabolic profile of dairy cows under moderate negative energy balance. Prolonged use of choline reduced the number of cases of endometritis, while supplementation for 20 days in antepartum reduced the interval between parturition and conception.