Context Yields from Brazilian beef-production systems do not always match the expected potential of a forage-based beef-production system. This efficiency is dependent on adjustments of grazing intensity and supplement utilisation to achieve higher bodyweight gain and lower methane emission. Therefore, more studies are necessary to evaluate the association between pasture management and supplement doses. Aims The aim of the present study was to determine nutrient intake, nutrient digestibility, animal performance, carcass characteristics and enteric methane emissions of young Nellore bulls grazing Urochloa brizantha cv. Marandu pastures. Methods One hundred and forty-eight yearling bulls (230 ± 17 kg) were randomly assigned to a grazing-by-supplementation strategy that was designed to allocate three different sward heights with differing levels of supplementation during the wet season. Treatment combinations were (1) low sward height with high supplementation (LH-HS, 15-cm sward height and supplementation at 0.6% of bodyweight (BW)); (2) low height with moderate supplementation (LH-MS, 15 cm and 0.3% BW); (3) moderate height with moderate supplementation (MH-MS, 25 cm and 0.3% BW); (4) moderate height with low supplementation (MH-LS, 25 cm and 0.1% BW); (5) high height with low supplementation (HH-LS, 35 cm and 0.1% BW); and (6) high height with no supplementation (HH-WS, 35 cm). Key results Bulls in the HH groups had a greater herbage intake than did those in the LH groups (P < 0.01). Bulls in the LH-HS treatment resulted in a greater (P < 0.01) carcass average daily gain than that obtained with LH-MS, MH-LS or HH-WS treatment. Higher stocking rate with the LH treatment resulted in greater gains per hectare in terms of both BW and carcass (P < 0.01). Carcass yield was greater for bulls maintained with the LH-HS treatment (54.3% BW). Higher enteric methane emissions were observed from bulls under the HH treatments (P < 0.01). Conclusions Comparing carcass gains per hectare and low methane emissions, the present study indicated that pasture management towards a low sward height combined with 0.3% or 0.6% BW supplementation can result in a greater nutrient utilisation efficiency of bulls. Implications Results provided information to obtain better gains per animals and area, also decreasing methane emission of beef cattle production system.

The effects of differing post-weaning management systems applied during the wet season were evaluated on the performance of 108 young Nelore (Bos taurus indicus) bulls finished on grasslands or feedlot system during the dry season. In Exp. 1, three grazing heights (15 cm, 25 cm, and 35 cm) of Brachiaria brizantha (Hochst ex A. Rich) Stapf Marandu were evaluated during the wet season with bulls receiving 0.3% of body weight (BW) in supplementary feed. In Exp. 2, supplementation levels were decreased as grazing heights were increased such as: (1) low height (15 cm) and high supplementation (0.6% BW) (LH-HS); (2) moderate height (25 cm) and moderate supplementation (0.3% BW) (MH-MS); or (3) high height (35 cm) with no supplementation (HH-NS). In both experiments, at the end of the wet season, a half of the bulls were finished on grasslands and receiving 1.0 kg/100 kg BW of dietary supplementation while the remaining bulls were placed in a feedlot system. A non-linear regression test was applied (linear plateau) to estimate the point of stabilization of DMI on feedlot. The experimental design was completely randomized in a factorial arrangement 3 (post-weaning system) × 2 (finishing systems), consisting of three replicates (lots of three bulls) per treatment (n = 18, each Exp.). In the Exp. 1, the post-weaning system using 35 cm of grazing height had greater BW (P = 0.04) through the finishing phase in comparison with bulls grazing 15 cm of grazing height. However, the ADG during the initial 21 days of the finishing phase was changed by grazing height used during the post-weaning phase (P = 0.004), and by finishing system (P = 0.007). The post-weaning system did not alter the carcass weight (P = 0.63), but the bulls finished on grasslands exhibited greater carcass weight (P = 0.02) than bulls finished on feedlot. In the Exp. 2, non-supplemented bulls (HH-NS) took a longer time (±10%) to DMI stabilization on feedlot (P b 0.01). There were no changes in the carcass weight caused by post-weaning system (P = 0.84), or by finishing system (P = 0.14). The evaluated systems combining increasing grazing height and decreasing supplementation level during the post-weaning phase can be used during the wet season according to the economic background or production target, once these systems do not influence the finishing phase.

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To evaluate the foraging behaviour of yearling bulls grazing on Marandu grass, we conducted two experiments. In the first experiment (Exp. 1), three grazing heights of 15, 25, and 35 cm were evaluated, with bulls receiving 0.3% of body weight (BW) of supplement (161 g kg-1 crude protein (CP) and 20.1 MJ kg-1 gross energy (GE)); in the second experiment (Exp. 2), supplementation levels were decreased as grazing height increased: (1) low height (15 cm) and high supplementation (0.6% BW: 142 g kg-1 CP and 18.9 MJ kg-1 GE (LH-HS)); (2) moderate height (25 cm) and moderate supplementation (0.3% BW: 161 g kg-1 CP and 20.1 MJ kg-1 GE (MH-MS)) or (3) high height (35 cm) without supplementation (HH-WS). Ingestive behaviour was evaluated by direct visual observations, and intake using markers. It was used 9 paddocks each experiment. The experimental design was completely randomized, analysing effects by polynomial orthogonal contrasts (Exp. 1) and Tukey test (Exp. 2). In Exp. 1, a linear decreasing response to daily grazing time (P < 0.01) was observed, whereas a linear increasing response to herbage intake (P < 0.01) was observed with increased grazing height. In Exp. 2, LH-HS bulls had lower herbage intake (P < 0.01) than their counterparts. Bulls from both experiments showed increased grazing activity after 12 PM (P < 0.05). The herbage intake substitution effect of supplements can be explored as a production strategy, as the adjustment of supplementation levels can promote high dry matter intake as well as performance in beef cattle, in conditions of low grazing height or low forage allowance, even with a high stocking rate.

The food industry is continually growing with new products becoming available every year. Extrusion combines a number of unit operations in one energy efficient rapid continuous process and can be used to produce a wide variety of snacks foods. The objective of this study was to evaluate the effect of extrusion temperature, screw speed, and amount of cassava leaf flour mixed with cassava starch on the physical properties of extruded snacks processed using a single screw extruder. A central composite rotational design, including three factors with 20 treatments, was used in the experimental design. Dependent variables included the expansion index, specific volume, color, water absorption index, and water solubility index. Among the parameters examined, the amount of cassava leaf flour and extrusion temperature showed significant effects on extruded snack characteristics. Mixtures containing 10% of cassava leaf flour extruded at 100°C and 255 rpm shows favorable levels of expansion, color, water absorption index, and water solubility index. Key words: Extrusion, protein, starch, Manihot esculenta Crantz ResumoA indústria de alimentos está crescendo continuamente com novos produtos sendo lançados no mercado a cada ano. A extrusão combina diversas operações unitárias em um processo eficiente, rápido e contínuo e que pode ser usado para produzir uma ampla variedade de snacks. Este trabalho teve como objetivo avaliar o efeito da temperatura de extrusão, rotação de rosca e porcentagem de farinha de folhas de mandioca, misturada com fécula de mandioca, sobre as propriedades físicas dos snacks processados em extrusora monorosca. Foi utilizado o delineamento experimental central composto rotacional para três fatores totalizando 20 tratamentos, considerando como variáveis dependentes o índice de expansão (IE), volume específico (VE), cor (L*, a* e b*), o índice de absorção de água (IAA) e o índice de solubilidade em água (ISA). Dentre os parâmetros estudados a porcentagem de farinha de folhas de mandioca e a temperatura de extrusão exerceram efeito mais pronunciado sobre as características avaliadas nos snacks extrusados. Misturas contendo 10% de farinha de folhas de mandioca extrusadas a 100ºC e 255rpm apresentam valores adequados de expansão, cor, índice de absorção de água e índice de solubilidade em água.