ABSTRACT: Owing to the lack of information in the literature about the ideal feeding frequency adopted by feedlot systems, this study was designed to evaluate the effect of different feeding frequencies on performance, carcass traits, feeding behavior and rumen morphometrics of Nellore cattle. Forty-eight yearling bulls were housed in individual pens with an average initial body weight of 358.2 kg. The experiment was designed as a completely randomized block and the treatments were the feeding of cattle one, two, three, or four times daily (n = 12 per treatment). Orthogonal contrasts were used to assess linear, quadratic and cubic relationship between feeding frequency and the dependent variable. As feeding frequency increased, final body weight (p = 0.03) and average daily gain (p = 0.01; one: 0.98 kg d–1; two: 0.96 kg d–1; three: 1.18 kg d–1; four: 1.14 kg d–1) increased linearly and the feed:gain ratio decreased (p = 0.02). Also, as feeding frequency increased, hot carcass weight was affected cubically (p = 0.01; one: 246.9 kg; two: 243.0 kg; three: 263.1 kg; four: 258.1 kg). During the adaptation period dry matter intake variation was affected cubically (p ≤ 0.05; one: 16 %; two: 23 %; three: 14 %; four: 16 %). Increases in feeding frequency affected papillae height (p < 0.01) and papillae surface area (p < 0.01) cubically, as well as producing increases in the mitotic index (p = 0.05; one: 9 %; two: 11 %; three: 13 %; four: 13 %) and cells in proliferation (p = 0.05) linearly. Thus, Nellore yearling bulls should be fed three times daily in feedlot operations.

O objetivo com este estudo foi avaliar o efeito do probiótico a base de bactérias produtoras de lactato (DBR) e da monensina sódica (MON) sobre o desempenho produtivo e características de carcaça de bovinos Nelore terminados em confinamento. Foram utilizados 18 machos, não castrados, com média de idade de 18 meses e 362,0 ±30,0kg de peso vivo inicial, divididos em três tratamentos: 1) 2g de DBR; 2) 1g de DBR + 138mg de MON e; 3) 275mg de MON, caracterizando delineamento inteiramente casualizado, com 6 animais por tratamento, divididos em 18 baias (1 animal/baia) em sistema de alimentação do tipo Calan Gate. O experimento teve duração de 84 dias, os animais foram pesados e submetidos a avaliações de ultrassonografia a cada 28 dias. Não houve efeito dos aditivos alimentares em relação ao peso vivo final e consumo de massa seca em percentagem do peso vivo. O ganho de peso diário foi menor nos primeiros 28 e 56 dias de estudo para animais que consumiram MON e DBR+MON, porém não foram observadas diferenças entre os tratamentos no período total. Animais alimentados com DBR+MON apresentaram maior consumo de massa seca durante todo o estudo, porém pior conversão alimentar que aqueles alimentados com DBR ou MON. Animais alimentados com DBR+MON apresentaram menor rendimento de carcaça que aqueles suplementados com DBR apenas e animais suplementados com MON tiveram maior espessura de gordura subcutânea ao final do estudo. A suplementação com o DBR apenas, pode ser uma alternativa para substituir a monensina.

The objective of this study was to evaluate the effect of probiotic based on lactate-producing bacteria (DBR) and sodium monensin (MON) on feedlot performance and carcass traits of feedlot Nellore cattle. The experiment was designed as a completely randomized design, replicated 6 times, in which 18 18-months-old yearling Nellore bulls (362,0 ± 30,0kg) were fed in individual pens for 84 days (1 animal/pen) in Calan gate system according to the treatments: 1) 2g of DBR; 2) 1g of DBR + 138mg of MON and; 3) 275mg of MON. The experiment lasted 84 days; the animals were both weighed and evaluated by ultrasound every 28 days. There was no effect of feed additives on final body weight and dry matter intake, expressed as percentage of body weight. The average daily gain was lower in the first 28 and 56 days of the study for animals fed MON and MON+DBR, but overall, no differences were observed between treatments were detected. Animals fed MON+DBR showed higher dry matter intake throughout the study, but lower feed conversion than those fed with DBR or MON. Animals fed MON+DBR had decreased dressing percentage than those supplemented with DBR only. In addition, animals fed only MON had thicker back fat by the end of the study. Supplementation with DBR may eventually be an alternative to replace MON.