Escore de enchimento ruminal como ferramenta de monitoramento da saúde em vacas leiteiras no período de transição

Abstract

The transition period is a critical phase in the productive lives of dairy cows, due to the increase in their nutritional requirement, concomitant with a physiological reduction in dry matter intake, and immune compromise. Due to these factors, this period is associated with a catabolic state, with a high incidence of metabolic-nutritional and infectious diseases, leading to economic losses and deterioration of animal welfare. Since many of these diseases are preceded by a decrease in dry matter intake (DMI), the evaluation of consumption indicators could serve to predict disease risk during the transitional period. As the rumen fill score (RFS) presents a good correlation with DMI, the present dissertation had two objectives: 1 – To correlate and compare rumen fill (RFS, 1 to 5) with blood indicators of negative energy balance. 2 – To validate the rumen fill score as a health monitoring tool and rate of return to cyclicality when it comes to dairy cows’ pre-calving. In order to answer the objectives, a cohort study was carried out with 113 Holstein multiparous cows, and the results of each objective are presented in 2 separate articles. To respond to objective 1 blood samples were collected to analyze the concentrations of βOH-butyrate (BHBA), non-esterified fatty acids (NEFA), cholesterol and calcium at week -2, -1, calving, + 1, + 2, +3, and simultaneously, RFS and cow’s body condition score (BCS) were measured. It was verified in this study that the RFS is correlated mainly with the BCS. Also, it was observed that the RFS was associated with blood indicators studied in pre and post partum periods, and cows with higher RFS (RFS 3) had higher concentrations of calcium, BHBA and cholesterol in prepartum. In the postpartum period, cows with RFS 1 had higher NEFA values and lower cholesterol than cows with RFS 3. To respond to objective 2, the RFS was measured at week -2, -1 and calving, clinical diseases were diagnosed and the return to cyclicity between the 4th and 8th week postpartum was evaluated. RFS was determined as a predictor of the most prevalent diseases (metritis, mastitis, placental retention, displaced abomasum and lameness). It was observed that EER≤2 two weeks before calving was a good predictor of all diseases described above, with sensitivity varying from 53% to 75% and specificity of 80%. On the other hand, cows with EER1 during prepartum and calving returned to cyclicity later and in a lower percentage when compared to cows with EER3. Therefore, the ruminal filling score correlated with the blood indicators during the transitional period, and served as a predictor for the diseases of the transition period and return to cyclicity. It can be used as a monitoring tool for the health of multiparous dairy cows.