Níveis e frequência de suplementação de novilhos de corte a pasto na estação seca

Abstract

The objective of this study was evaluate the levels of protein-energy supplementation, offered at different frequencies, to growing steers kept on Brachiaria decumbens pasture during the dry season. Twenty-five no castrated steers were used, 191 kg initial average weight, in a randomized complete block design, with five replications per treatment in a 2 × 2 + 1 factorial arrangement, that is, two protein-energy supplementation levels (0.3 and 0.6% on the basis of body weight (BW)), two supplement distribution frequencies - daily or on alternate days, plus an additional treatment (only mineral supplementation). Forage dry matter intake (FDMI) was estimated using two markers, chromic oxide and indigestible dry matter (DMi). The dry matter intake of the supplement was measured daily because the supplement was offered to each steer individually. The supplementation increased dry matter intake and the average daily gain (ADG) (1.66% of BW and 290 g/day), compared to the additional supplement (1.49% of BW and -107 g/day). The herbage dry matter and neutral detergent fiber intake were greater animals supplemented only with mineral mixture (1.48 and 1.1% BW), and smaller for the supplemented ones (1.27 and 0.95% of BW), respectively. Forage intake reduction did not differ among the supplemented levels (299 g/day). The supplementation with 0.6% BW presented a better average daily gain than the 0.3% BW (343 versus 238 g/day), but it was 39% less efficient at converting the supplement into live weight gain. There was no effect of frequency on the variables studied. Supplementation on alternate days seems to be an interesting alternative for cattle feeding, regardless of the amount of supplement offered.