Supplementation with different energy and protein sources on the feeding behavior and performance of dairy heifers grazing Marandu during the dry season

Abstract

This study aimed to evaluate the effect of supplementation different energy and protein sources in the dry season of the year, on body development and diurnal feeding behavior of crossbred Gir x Holstein dairy heifers 12.8 ± 4.6 months old, 215.50 ± 43.2 kg average body weight were distributed in Brachiaria brizantha cv. Marandu pasture with supplements being offered daily in proportion of 0.75% of the body weight. A completely randomized block design with a 2 x 2 factorial arrangement was used, with six replicates per treatment. Supplements contained whole soybean (WS) or whole cottonseed (WC) as the protein sources and citrus pulp (CPU) or corn (C) as the energy sources. Marandu grass pasture was managed according a rotational grazing system, six days grazing and 30 days of rest period. It was recorded the animals weight, height at withers, heart girt, rump length and corporal score after the grazing cycle. The considered behavioral variables were grazing time, ruminating time, idle time, trough time. No significant differences on the initial, heart girt, height at withers, rump length and corporal score final and initial to protein and energy sources. However, a significant effect was observed (P<0.05) in heifers supplemented with WC had greater final body weight and heart girt and average daily gain live weight (271.1 kg, 152.2 cm and 0.382 kg/animal, respectively) in comparison to those with WS (251.1 kg, 148.7 cm and 0.255 kg/animal, respectively). The CPU base supplement resulted in smaller grazing time and greater ruminating and idle time (P>0.05). The WS base supplemented animals had kept lesser time eating supplement in comparison to the WC base supplemented ones (P<0.05), with no variation in grazing, rumination or idle times regarding protein font (P>0.05). The hour of the day influenced all the considered behaviors (P<0.01).