PSXII-9 Effect of different levels of supplementation on the ingestive behavior of Nellore bulls raised on pasture during the dry season.

Abstract The objective of this study was to evaluate the effect of supplementation levels on the ingestive behavior of Nellore cattle raised on Uroclhoa Brizantha cv, Marandu pastures during the dry season under continuous stocking. Thirty-six Nellore bulls (body weight = 325 kg; age = 20 months) were blocked by body weight after 16 hours of fasting from solids and liquids and distributed into 12 paddocks of 1 hectare each (3 animals/paddock) to evaluate the following treatments: MS: animals supplemented only with mineral salt ad libitum; PS: animals receiving protein supplement offered at 1 g/kg BW (400 g crude protein/kg); and PES: animals receiving protein-energy supplement offered at 3 g/kg BW (300 g crude protein/kg). All animals were supplemented daily at 9:00 AM. The experimental period lasted 132 days and was divided into adaptation periods (-20 to -1) and evaluation periods (days 0 to 112). The ingestive behavior of all animals was evaluated from 6:00 AM on day 20 to 6:00 AM on day 21 (24 hours of evaluation), each 10 minutes. The time each animal remained idle, ruminating, at the trough and grazing was evaluated, in addition, the percentage of animals grazing throughout the day was analyzed. Data were analyzed by ANOVA using PROC MIXED, SAS 9,4. The percentage of animals grazing was analyzed as repeated measures over time using SAS REPEATED. Animals supplemented with SP presented similar idle time to MS and PES animals (9,39 vs, 8,79 and 9,84 hours/day; P >0,115), but PES animals remained idle longer than MS animals (9,84 vs, 8,79 hours/day; P = 0,008). No effect of treatments was observed for time grazing, at the trough and ruminating (P > 0,161). In general, at all supplementation levels, a greater proportion of animals grazed in the morning and late afternoon; however, MS animals started grazing earlier. In summary, increasing the supplementation level up to 3 g/kg of body weight does not interfere with grazing time, but increases idle time.