Espécies de pastagem anual de verão são utilizadas no Brasil para fornecer forragem em épocas desfavoráveis e/ou atender categorias mais exigentes. Objetivou-se avaliar os parâmetros produtivos da forragem e o desenvolvimento de novilhos (195,0±13,40 kg; 14±0,19 meses) em pastagens de milheto ou sorgo forrageiro. Os tratamentos consistiram em: Pastagem de sorgo (Sorghum bicolor L. Moench) e Pastagem de milheto (Pennisetum americanum Leeke). O delineamento experimental foi de blocos ao acaso. O período experimental foi de 84 dias, subdivido em três períodos de avaliação. A pastagem de milheto proporcionou maior oferta de lâminas foliares (3,64 vs. 1,98 kg MS/100 kg de peso corporal), porém as demais características não diferiram entre as espécies forrageiras (P>0,05). A evolução de peso e estrutura corporal dos novilhos foi semelhante entre as forrageiras, assim como, a produtividade animal por unidade de área (P>0,05). Os períodos de avaliação influenciaram significativamente a produção vegetal e animal (P<0,05). O avanço no ciclo de utilização das pastagens resultou em piora na estrutura da forragem, com menor oferta de lâminas foliares, surgimento acentuado de espécies espontâneas e redução na produtividade da forragem. Houve evolução de peso e escore corporal com o avanço dos períodos de pastejo, com diferença significativa a cada 28 dias (P<0,05). Sorgo forrageiro e milheto apresentam parâmetros produtivos similares, mostrando-se como boas opções alimentares para novilhos em crescimento. O avanço no ciclo produtivo acarreta modificações na estrutura da pastagem, reduzindo a produtividade por área.

The objective was to evaluate the inclusion of chemical additives or bacterial inoculant in corn silage. The experimental design was completely randomized with five treatments: silage without additive; silage added with urea (3.0%); silage with limestone (3.0%); silage added with crystal sugar (3.0%); and silage with a bacterial inoculant. Five of them were opened during the fermentation process (15 days) to measure pH, and three were opened 60 days after ensiling to evaluate the ammonia nitrogen and organic acids content. For the pH at the end of the fermentation process, higher values were found for the limestone additive, followed by the silage with urea, which had higher participation of lactic acid, 19.06 ppm for limestone and 18.95 ppm for urea. Higher concentrations of acetic acid were observed in inoculant silages (18.49ppm) or silage without additive (18.46ppm). The ammonia nitrogen content was higher in the silage with urea (23.74mg dL-1), followed by the silage without additive (7.54mg dL-1), which also had the highest concentration of butyric acid (4.19ppm). The use of additives reduced the concentration of butyric acid in the silage. The bacterial inoculant was the most efficient in decreasing the pH of the ensiled material.

O objetivo deste estudo foi avaliar os componentes não carcaça de novilhas terminadas em pastagem de Tifton 85, suplementadas com três diferentes fontes energéticas. Foram utilizadas 30 novilhas, Charolês x Nelore, com idade e peso médio inicial de 26 meses e 274,5 kg. O delineamento foi o inteiramente casualizado, sendo as fontes energéticas utilizadas: grão de milho, grão de aveia branca ou grão de cevada, o nível de suplementação foi de 1% PV, com 10 repetições por estratégia de suplementação empregada. Os pesos de abate (PA), de corpo vazio (PCVZ) e a relação PCVZ/PA foram similares entre estratégias de suplementação. O peso total de órgãos relativos a 100 kg de PCVZ, foi superior para os animais suplementados com milho, 3,43% PCVZ. O peso relativo de rúmen-retículo foi superior para as fêmeas que receberam cevada, 1,72% PCVZ, porém o peso do trato gastrointestinal não diferiu entre as fontes energéticas utilizadas. O peso dos componentes periféricos e o total de gorduras não foram alteradas pelas diferentes fontes energéticas utilizadas. A suplementação com grão de aveia branca reduz o rendimento de órgãos internos e o rendimento de partes do trato gastrintestinal, em relação ao grão de milho e à cevada, respectivamente.

The effect of termination of steers in a feedlot using the total substitution of soybean meal by slow-release or agriculture urea on the non-carcass components was evaluated. Twenty-seven purebred and Charolais × Nellore castrated crossbred steers (mean age 20 months, mean initial weight 293 kg) were allocated to received concentrates containing slow degradation urea, soybean meal, or agricultural urea. The experimental design was in randomized blocks (breed predominance), with three treatments and nine replicates, with the animal being the experimental unit. Diets did not lead to significant differences in empty body weight (EBW). The similarity between treatments was also verified in relation to EBW/slaughter weight, with mean values of 0.87 for treatments containing urea and 0.88 for soybean meal treatment. The gastrointestinal contents, both in absolute weight and in relation to EBW, were similar between the rations evaluated, with mean values of 54.33 kg and 13.52%, respectively. Steers fed with slow-release urea had a 32.8% higher weight of omasum relative to 100 kg of EBW (P < 0.05) compared to the animals fed with soybean meal.

Effect of pre-and postpartum body development on the rebreeding of first-calf heifers. Cien. Inv. Agr. 46(3):243-252. The objective of this study was to evaluate the effect of live weight and body condition score, measured at different growth stages, on the rebreeding of first-calf heifers. A total of 120 Nellore and Charolais crossbred heifers born between 2004 and 2008 were assessed. Their average age was 26±1 months, they were all from the same herd, and they received the same management from birth. To conduct this study, pre-and postpartum measurements of first-calf heifers were taken. The data were submitted to analysis of variance, and the means were compared using Student's t-test at a significance level of α=0.05. A higher live weight of the heifer at 24 months enabled early calving within the first calving season (r=-0.30). First-calf heifers that rebred had a higher live weight at weaning (361 kg vs. 333 kg) than those that did not, although their live weights at calving were similar (344 kg vs. 332 kg). The rebreeding of first-calf heifers that gave birth with the same body condition score as in the first calving was dependent on positive live weight gain until the end of the following breeding season, especially during the calving-weaning period.

Dry matter and neutral detergent fiber contents act as physical regulators of voluntary intake in ruminants. Therefore, different levels of these components may interfere with animal performance and require careful assessment of the used raw material. This study was conducted with the purpose to assess the effect of soybean hulls and white oat in distinct or associated uses in the concentrate diet on the ingestive behavior of cattle. Thirty-six steers with an initial mean age of 20 months and initial mean weight of 226 kg were used. The diet was composed of 50% sorghum silage and 50% concentrate based on dry matter. The tested diets were soybean hulls (concentrate fraction composed mainly of soybean hulls), white oat grains (concentrate fraction composed mainly of white oat grains), and mixture (concentrate fraction composed of equal parts of soybean hulls and white oat grains). The experimental design was a randomized block design with 12 animals per diet. The data were compared by the PROC MIXED procedure with repeated measures in time, and the means were compared by the least significant difference test at 5% significance level. Diets presented different contents of neutral detergent fiber (66, 56, and 47%) and lignin (3.2, 3.7, and 4.1%) as the percentage of white oat grain increased in the diet. The total rumination time was lower (447 minutes) for animals that received equal parts of soybean hulls and white oat grains in the diet when compared to animals receiving a diet containing soybean hulls (483 minutes) and white oat grains (495 minutes), with no difference from each other. Animals fed a diet containing soybean hulls and white oat grains showed longer feeding time, a higher number of daily meals, shorter rumination time, shorter time spent chewing, and fewer number of chews per bolus and day. This diet results in a better dry matter and neutral detergent fiber rumination efficiencies.