Dry matter intake and feed efficiency of Nellore bulls finished with different feedlot time

The present study aims to evaluate the effect of feedlot time on dry matter intake (DMI) and feed efficiency (FE) of Nellore young bulls. Three hundred and fifty two animals (initial body weight (BW) = 389 ? 33.8 kg and 26 months old) were distributed into 36 pens (experimental unit) to evaluate the feedlot times, which consisted of 61, 89, 117 and 145 days . It was used nine pen by feedlot time. The diet was formulated according to the nutritional requirements for gain of 1.5 kg / day. The roughage: concentrate ratio during the adaptation (15 days) was 21:79; then passed to 12:88. It was used sugarcane bagasse as roughage and the concentrate was composed of corn, citrus pulp, peanut meal, protected fat, mineral core virginiamycin (25 ppm) and monensin (27ppm). The termination diet had 14% of crude protein and 76% of total digestible nutrients; (2.88 Mcal / kgDM). At the end of each feedlot time, the animals were weighed (with solid and liquid fasting for 16 hours) to determine the average daily gain (ADG) and body weight (BW). The data was analyzed using orthogonal contrasts in a block design (shared by initial body weight). The data was subjected to analysis by orthogonal contrasts using the MIXED procedure of SAS (9.0). The significance was declared at P <= 0.10. The ADG showed decreasing linear effect (P < 0.01), being observed values of 1.81, 1.62, 1.42 and 1.34 kg to 61, 89, 117 and 145 days of feedlot time respectively. There was no difference in the DMI (10.1 kg / day) between the feedlot times (P > 0.10). A feed conversion showed a linear increase (P < 0.01), being observed values of 5.72, 6.28, 6.97 and 7.62 kg DM for 61, 89, 117 and 145 days of confinement respectively. The FE showed decreasing linear effect (P < 0.01), being observed values of 0.176, 0.160, 0.144 and 0.132 for 61, 89, 117 and 145 days of feedlot time respectively. Factors related to changes in energy efficiency for deposition of tissues, especially fat in the finishing phase, may be associated with reduced feed efficiency of cattle fed in feedlot time for long-lasting periods.