Crude glycerin in diets for lactating cows grazing on tropical pasture: ingestive behavior

Abstract

The objective of this study was to evaluate the ingestive behavior of lactating dairy cows grazing on tropical pasture supplemented with different levels of crude glycerin in the diet. Ten lactating cows, ¾ Gir x ¼ Holstein Dairy cows, primiparous, and 109 ± 24 days of lactation, mean age 30 ± 6 months and mean body weight of 426.2 ± 68.29 kg, distributed into five treatments, in double (5x5) Latin square design, were used. The treatments consisted of inclusion levels of crude glycerin in the diet (0.0, 4.5, 9.0, 13.5, and 18.0% dry matter basis). The behavior evaluation was performed on the 14th day of each period, with observations every five minutes for a period of 24 hours. The results were analyzed statistically using analysis of variance and regression at 5% probability. For the grazing time, other activities, rumination, feeding trough, the number of grazing periods, other activities, rumination and feeding trough, as well as bit rate, number and time of chews per bolus, and efficiencies of eating and ruminating were not significant differences among crude glycerin levels in the diet (P>0.05). The inclusion of crude glycerin in diets for lactating cows in tropical pastures does not promote changes in ingestive behavior. The absence of negative effects related to the use of this byproduct in substitution of corn in these conditions allows its use in up to 18% crude glycerin in diets for dairy cows without changing the behavioral parameters related to food intake.