This study aimed to evaluate the ingestive behavior of steers on Brachiaria brizantha pasture fed diets with increasing levels of concentrate supplementation. Thirty-two crossbred steers in the finishing phase with average weight of 420 ± 8 kg were distributed in a completely randomized design with four treatments and eight replicates per treatment. Their behavior was assessed every 5 min for 24 h, in the middle of the experimental period. Variance and regression analyses at 0.05 % probability were adopted. The times spent grazing and ruminating reduced linearly (P <0.05), whereas the times spent at the trough (eating) and on other activities increased linearly (P <0.05) as the supplementation levels were elevated. The total feeding and chewing times decreased linearly (P <0.05) as the concentrate levels in the diet were elevated. By increasing the supplementation levels, the number of bites per day decreased linearly (P <0.05), and the feed efficiency of dry matter increased quadratically. Rumination efficiency of dry matter increased linearly (P <0.05) with increasing levels of concentrate supplementation. Grazing and rumination activities are reduced when the time devoted to other activities and at the trough are increased, as a result of the substitution effect.

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ResumoObjetivou-se avaliar o desempenho de bovinos Nelore em pastagem de capim-Tanzânia (Panicum maximum Jacq. cv. Tanzânia-1) adubado com nitrogênio ou consorciado com estilosantes Campo Grande (Stylosanthes ssp). Utilizou-se um delineamento experimental em blocos ao acaso com parcelas subdivididas, com três repetições e quatro tratamentos: Tanzânia + Estilosantes; Tanzânia + 75 kg de N ha -1 ano -1 ; Tanzânia + 150 kg de N ha -1 ano -1 ; Tanzânia + 225 kg de N ha -1 ano -1 . Nas subparcelas foram avaliadas as estações. O maior ganho médio diário (GMD) durante o outono foi observado nos tratamentos em consórcio e 75 kg de N ha -1 ano -1 . O GMD observado nos tratamentos com 150 e 225 kg de N ha -1 ano -1 foram superiores aos demais na primavera e verão. A taxa de lotação (TL) foi semelhante entre as estações avaliadas. Foi observada maior TL quando foram utilizadas as maiores doses de adubação nitrogenada. O ganho de peso vivo por área foi superior na primavera e no verão quando comparado ao outono. A inclusão de leguminosas no sistema pecuário diminui a dependência do uso excessivo de fertilizantes nitrogenados e contribui no desempenho animal. Palavras-chave: Forragicultura, ganho médio diário, leguminosa, massa de forragem, taxa de lotação AbstractThe objective was to evaluate of Nelore performance on pasture of Tanzania (Panicum maximum Jacq. cv. Tanzania-1) fertilized with nitrogen or mixed with Stylosanthes Campo Grande (Stylosanthes spp). It was used a randomized complete blocks with split plots design and three replicates of four treatments: Stylosanthes + Tanzania; Tanzania + 75 kg de N ha -1 ano -1 ; Tanzania + 150 kg de N ha -1 ano -1 ; Tanzania + 225 kg de N ha -1 ano -1 . Plots were assessed by stations. The highest average daily gain (ADG) during the fall was observed in treatment in the consortium and 75 kg de N ha -1 ano -1 . The ADG in the treatments of 150 and 225 kg de N ha -1 ano -1 were superior to others in spring and summer. Stocking rate (SR) was similar between the stations studied. The value of SR was higher when it was used the highest dose of nitrogen fertilizer. The weight gain per area was higher in the spring and summer compared to autumn. The inclusion of legumes in livestock system reduces the dependence of the overuse of nitrogen fertilizers.

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The aim of this study was to evaluate the effect on intake, digestibility and fractionation of carbohydrates and proteins of cottonseed cake as an alternative protein source in rams diets. The diets were composed of corn silage, soybean meal, ground corn, urea, and cottonseed cake (0, 70, 140 and 210 g/kg dry matter (DM)) in a roughage/concentrate ratio of 50:50. Thirty-two Santa Ines rams, average age 12 months and weight 27.48 ± 4.96 kg were distributed in a completely randomised design. A reduction of 0.161 g/day in crude protein (CP) intake was observed for each gram of cottonseed cake inclusion. The intake of non-fiber carbohydrate (NFC) decreased by 0.511 g/day for each gram of cottonseed cake inclusion. Similarly, the ratio between intake of DM (p = 0.034), CP (p < 0.001), NFC (p = 0.004) and body weight decreased with cottonseed cake inclusion. Inclusion of cottonseed cake caused decreases in the digestibility coefficients of DM (p < 0.001), CP (p < 0.001) and NFC (p = 0.002). A reduction of 0.716 g was observed in carbohydrate fraction A + B1 (p = 0.006). The inclusion of cottonseed cake in the rams feed should be carried out with caution because this by-product promotes linear reduction in intake and digestibility nutrient, in addition to modifying the amounts of digestible and indigestible fractions in the diets.