Desempenho e comportamento ingestivo de novilhos e vacas sob freqüências de alimentação em confinamento

Abstract

The experiment was realized with the objective of study the performance and feeding behavior of steers and cull cows, feedlot finished, submitted to distincts feeding frequencies, two (7:00 and 19:00 hours), three (7:00, 13:00 and 19:00 hours) or four (7:00, 11:00, 15:00 and 19:00 hours) times a day. Charolais-Nellore crossbred steers, 21 months old, and cull cows, 66 months old, from the same population, were used. The diet was composed by corn silage (40%) and concentrate (60%). The performance datas were obtained by the weight and body condition of the animal at pre-established periods, by the measures of the quantity of the food that was supplied and the respective leftovers, chemical analysis of the diet ingredients and leftovers. The behavior parameters were obtained after three evaluations for 48 hours each one, with the register of animals activity at each 5 minutes, beyond the meansure of chews per bolus of rumination and duration of it. The interaction between feeding frequencies and feedlot period was significant for voluntary intake of dry matter (DM) and of digestible energy (DE). The increase of the feeding frequencies did not affect the average daily weight gain (1.54, 1.53 and 1.50 kg, repectively) and the efficiency of converting the dry matter (8.90, 8.59 and 8.31 kg of DM/kg of weight gain) and DE (26.42, 25.34 and 24.58 Mcal/kg of weight gain) into weight gain. Any significant interaction was observed for feeding frequency and animal category. The cows showed higher average daily intake of DM expressed by animal (13.92 vs. 10.76 kg) and per metabolic weight in relation to steers, causing any significant modification on average daily weight gain (1.60 and 1.45 kg, repectively). Cows were 17.72 and 17.30% less efficient then steers on converting DM and DE into weight gain, respectively. The interaction between animals category and feedlot period was significant for body condition gain. For cows, the body condition gain was more proimminent during the first two feedlot periods, while for the steers it was more proimminent during the last period. The interaction between feeding frequency x animal category did not affect the behavior parameters studied. Animals fed three times daily ruminated more time in the stand-up position than those fed four times (1.16 vs .68 hours). However, when rumination in the two positions (stand-up plus lay down) was considered, no difference was observed (6.76 vs 6.9 h). Animals fed three times also spent more time consuming water (.33 h) in relation to two (.25 h) or four (.19 h) times fed animals. Feeding frequency did not affect the leisure and ingestion activities. Animals remained in the stand-up position during 38.92% of the time and in the lay down position 61.02%. The feeding frequency did not affect the rumination activities, while the animal category affected the number of chews per bolus, per kg of dry matter consumed and the intake rate. Steers showed 55.7 chews/bolus and 2,163.32 chews per kg of dry matter consumed while the cows showed 51.69 and 1,591.13 chews, respectively. Dry matter intake rate was 3.01 kg/h for steers and 3.58 kg for cows.