Resumo A morfogênese é uma valiosa ferramenta para a compreensão da dinâmica do pasto, porém os estudos morfogênicos referentes à cultura do sorgo ainda são escassos. O objetivo do presente estudo foi avaliar os efeitos de diferentes níveis de suplementação sobre as características morfogênicas do sorgo forrageiro. O experimento foi conduzido na Universidade Federal de Santa Maria entre janeiro e abril de 2013. O delineamento experimental foi inteiramente casualizado, com medidas repetidas no tempo, com três tratamentos e duas repetições. Os tratamentos consistiram em S 0,8 = pastagem de sorgo + 0,8 % PV de suplementação, S 1,0 = pastagem de sorgo + 1,0 % PV de suplementação e S 1,2 = pastagem de sorgo + 1,2 % PV de suplementação. Ao aumentar o nível de suplementação ofertado, observou-se menor valor para Folhas Vivas (2,77, 3,34 e 3,55) e Taxa de Elongação Foliar (0,06, 0,09 e 0,08). Não foram influenciadas (P<0,05) pelos diferentes níveis de suplementação as variáveis Taxa de Aparecimento Foliar (0,0041, 0,0043 e 0,039), Taxa de Senescência Foliar (0,05, 0,06 e 0,11), Filocrono (283,96, 265,21 e 278,62), Duração de Vida da Folha (1081,1, 986,25 e 788,79) e Duração de Elongação Foliar (350,58, 312,83 e 326,36).

Abstract Morphogenesis is a valuable tool for the dynamics understanding of the pasture, however the morphogenetic studies related to sorghum culture are still scarce as well. The objective of the present study was to evaluate the effects of the different levels of supplementation on the morphogenetic characteristics of sorghum forage. The experiment was performed of UFSM from January to April 2013. The completely randomized experimental design was used, with measures repeated in time, with three treatments and two repetitions. The treatments consisted in S 0.8 = sorghum pasture + 0.8 % LW of supplementation, S 1.0 = sorghum pasture + 1.0 % LW of supplementation and S 1.2 = sorghum pasture + 1.2 % LW of supplementation. By increasing the supplementation level offered it was observed a lower value for the Number of Live Leafs (2.77, 3.34 and 3.55) and Leaf Elongation Rate (0.06, 0.09 and 0.08) characteristics. The variables Leaf Appearance Rate (0.0041, 0.0043 and 0.039), Leaf Senescence Rate (0.05, 0.06 and 0.11) and Phyllochron (283.96, 265.21 and 278.62) were not influenced (P˃0.05) by the different supplementation levels. There was a difference (P<0.05) among the evaluation periods for Leaf Life Span (1081.1, 986.25 and 788.79) and Leaf Elongation Length (350.58, 312.83 and 326.36).

RESUMO. Objetivou-se, neste estudo, avaliar os efeitos da sobressemeadura de Aveia ou Azevém sobre as características produtivas e composição morfológica do capim Tifton85 mantido sobre pastoreio contínuo. Os três tratamentos estudados foram Aveia + Tifton85, Azevém + Tifton85 e Tifton85, distribuídos em delineamento inteiramente casualizado, constituindo quatro repetições de área por tratamento. O tratamento Azevém + Tifton85 apresentou massa de forragem 27% superior ao tratamento Aveia + Tifton85. O percentual de folha de Tifto85 foi superior para o tratamento Aveia + Tifton85 (41%), enquanto o percentual de colmo + bainha foi superior no tratamento Azevém + Tifton85 (64%). Observou-se maior percentual de folhas de Tifton85 no tratamento Aveia + Tifton85, enquanto o tratamento Azevém + Tifton85 apresentou maior proporção do constituinte colmo + bainha. A sobressemeadura de espécies de clima temperada mostrou-se alternativa viável, visto que potencializa o ganho de peso dos animais sem prejudicar o reestabelecimento produtivo do Tifton85.

ABSTRACT. This study aimed to evaluate the effects of oat or ryegrass over seeding on the productive characteristics and morphological composition of Tifton85 grass under continuous grazing. The three studied treatments were: Oat + Tifton85, Ryegrass + Tifton85 and Tifton85, distributed in a completely randomized design, constituting four replications of area per treatment. The Ryegrass + Tifton85 treatment presented a forage mass 27% superior to the Oat + Tifton85 treatment. The leaf percentage of Tifton85 was superior for the treatment Oat + Tifton85 (41%), while the percentage of stem + sheath was superior in the treatment Ryegrass + Tifton85 (64%). There was a higher percentage of Tifton85 leaves in the treatment Oat + Tifton85, while the Ryegrass + Tifton85 treatment presented a higher proportion of the stem + sheath constituent. Overfeeding species of temperate climate has proven to be a viable alternative, since it potentiates the weight gain of animals without damaging the productive re-establishment of Tifton85.

In this article we research the influence of different sources of carbohydrates (corn, soybean hulls or wheat bran) upon the digestive behavior of 24 confined castrated steers with an initial average age and weight of 20 months and 330 kg born from the cross between Charolais and Nellore. The diet was composed of 40% sorghum silage and 60% concentrate. The time spent on total ruminating (an average of 454.6 min/day) was not influenced by the source of carbohydrate. The animals from the wheat bran treatment spent less time idle (718 min) in relation to those on the corn and soybean hulls treatments, which did not differ between themselves (an average of 792 min/day). The steers from the wheat bran treatment remained less time feeding (184 min/day) compared with those fed the other treatments, whose average time of permanence in this activity was 214 minutes per day. The other studied variables did not present a significant difference between the treatments. Inclusion of wheat bran in the diet of the confined steers results in less spent time idle, while steers feeding on soybean hulls spend less time feeding. The use of corn, soybean hulls, or wheat bran in the diet of the confined steers does not affect the total cudding time.

The objective of this study was to evaluate the effect of carbohydrate sources (corn, soybean hulls or wheat bran) in the diet on performance of feedlot steers in the finishing phase. Twenty-four Charolais × Nellore crossbred steers, aged 22 months and initial weight of 335.0±10.9 kg were used in the experiment. Diets contained 40% sorghum silage and 60% concentrate. The intakes of dry matter (DM; 10.68, 10.16 and 10.34 kg/day) and crude protein (1.66, 1.70 and 1.72 kg/day) were not affected by diets with corn, soybean hulls or wheat bran, respectively. The intakes of neutral and acid detergent fiber were higher for soybean hulls, but the diet containing corn provided higher intake of non-fibrous carbohydrates, total digestible nutrients and digestible energy. Weight gain was higher and better feed conversion for animals fed corn (1.57 kg/day, 6.85 kg DM/kg gain) or soybean hulls (1.58 kg/day and 6.61 kg DM/kg gain) compared with steers receiving wheat bran (1.29 kg/day and 8.14 kg DM/kg gain) in the diet. There was no significant effect of carbohydrate sources on the final body score (3.78 points), energy conversion (28.25 Mcal digestible energy/kg gain), hot carcass yield (57.63 kg/100 kg BW) and fat thickness (3.1 mm). From an economic point of view, soybean hulls can be an alternative source of carbohydrate to corn in diets of finishing steers with 60% concentrate.

Estudaram-se os efeitos da substituição na dieta da silagem de milho por silagem de girassol (0, 33 e 66% MS) no comportamento ingestivo de novilhos em confinamento. Utilizaram-se nove novilhos castrados com peso vivo e idade média inicial de 288 kg e 20 meses, respectivamente, pertencentes aos grupos genéticos Nelore, 21/32Charolês (C) 11/32Nelore (N) e 21/32N 11/32C. O delineamento experimental utilizado foi o de blocos ao acaso, com três repetições por tratamento. As dietas testadas foram: 100 % de silagem de milho e 0 % de silagem de girassol; 70,94% de silagem de milho e 29,06 % de silagem de girassol; 38,27 % de silagem de milho e 61,73 % de silagem de girassol, todas com relação volumoso:concentrado 60:40. O tempo destinado ao ócio deitado foi maior para os novilhos que consumiram apenas silagem de milho como volumoso em relação aos que consumiram silagem de girassol. O tempo despendido em ócio em pé foi semelhante entre as dietas com 33 (1,84 hora) e 66 % de silagem de girassol (1,96 hora) e menor para aquela sem silagem de girassol (1,62 hora). O tempo em ruminação dos animais aumentou com a inclusão da silagem de girassol na dieta e correspondeu a 8,61; 8,76 e 9,45 horas, respectivamente, para 0; 33 e 66 % de silagem de girassol. Animais alimentados somente com silagem de milho apresentam maior eficiência de ruminação da matéria seca e da fibra em detergente neutro. O tempo despendido por refeição diminui com o aumento da participação da silagem de girassol.

The objective of this experiment was to evaluate the effect of replacing corn silage with sunflower silage (0, 33 e 66% DM) on the ingestive behavior of fedlot steers. Nine castrated steers were used, with average 288 kg initial live weight and 20 month old from the Nellore (N), 21/32Charolais (C) 11/32N and 21/32N 11/32C genetic groups. A randomized complete block experimental design was used, with three replications per treatment. The tested diets were: 100% corn silage and 0% sunflower silage; 70.94% corn silage and 29.06% sunflower silage and 38.27% corn silage and 61.73% sunflower silage, all with a 60:40 roughage:concentrate ratio. Time spent lying idle was greater for steers that consumed only corn silage as roughage compared to those that consumed sunflower silage. Time spent standing idle was similar between 33 (1.84 h) and 66% sunflower silage (1.96 h) and lower for 0% sunflower silage (1.62 h). The animals rumination time increased with the inclusion of sunflower on diet, with values of 8.61; 8.76 and 9.45 h, respectively for 0; 33 and 66% sunflower silage. Animals fed only with corn silage show better dry matter and neutral detergent fiber rumination efficiencies. The time spent feeding decrease with higher participation of sunflower silage.

O objetivo neste estudo foi avaliar as partes não-integrantes da carcaça de tourinhos abatidos entre 14 e 16 meses de idade alimentados com diferentes níveis de concentrado na dieta. Os animais foram terminados em confinamento até atingirem em média 400 kg de peso vivo. Foram utilizados 16 tourinhos alimentados com 22, 40, 59 ou 79% de concentrado na dieta, distribuídos inteiramente ao acaso, com quatro repetições por tratamento. A idade e o peso médio inicial dos animais foram de 9,32 meses e 192,44 kg, respectivamente. O peso de corpo vazio (PCVZ) e o rendimento de carcaça expresso em valores ajustados para o PCVZ foram similares entre os níveis de concentrado na dieta. O aumento no nível de concentrado na dieta promoveu diminuição linear do peso absoluto de intestino e aumentos lineares dos pesos absolutos da gordura ruminal e do abomaso. Quando os componentes foram expressos em valores ajustados para PCVZ e peso de abate (PA), verificaram-se aumentos lineares para pesos de patas, coração, intestinos, gordura de toalete, gordura do rúmen, conteúdo do trato gastrintestinal e conteúdo de gordura interna e diminuição linear do peso de cabeça e omaso com o aumento do nível de concentrado na dieta. O peso de abomaso foi quadraticamente influenciado pelo nível de concentrado, com valores mínimos estimados para os níveis de 68,0; 66,7 e 69,2% de concentrado na dieta, em relação ao peso absoluto, ajustado para o PCVZ e PA, respectivamente. O aumento do nível de concentrado de 22 para 79% promoveu aumento nos pesos relativos do conteúdo do trato gastrintestinal e gordura interna e não influenciou o conjunto dos órgãos internos, o peso de corpo vazio e o rendimento de carcaça ajustado para o PCVZ de tourinhos abatidos aos 14-16 meses com 400 kg.

The objective of this trial was to evaluate the non-integrant body components of the carcass from young bulls slaughtered at 14-16 months of age, fed different concentrate levels in the diet. The animals were feedlot finished until reaching 400 kg of body weight. Sixteen bulls were randomly distributed into four treatments: 22; 40; 59 or 79% concentrate in the diet. The initial average age and weight were 9.3 months and 192.4 kg, respectively. The empty body weight (EBW) and carcass dressing ajusted for empty body weight were similar among the different concentrate levels. The increase in the concentrate level in the diet promoted linear decrease for intestine absolute weight, and linear increase for ruminal and abomasum absolute fat weight. When the components were expressed as adjusted EBW values and slaughter weight (SW), linear increases were observed for weight of feet, heart, intestine, trim fat, ruminal fat, gastrintestinal tract content and internal fat, and linear decreases were observed for weight of head and omasum as the concentrate level increased. The response of the abomasum weight according to the concentrate level was quadratic, with the minimum values estimated for the concentrate levels of 68.0, 66.7 and 69.2%, in relation to the absolute weight, adjusted for EBW and SW, respectively. The increase in the concentrate level from 22 to 79% increased the ajusted weights of gastrintestinal tract content and internal fat; however, it did not affect the total internal organs, empty body weight and carcass dressing ajusted for empty body weight of bulls slaughtered at 14-16 months of age with 400 kg.