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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. Brazilian beef production produces animal protein mainly by using fibrous feeds such as tropical grasses, which reduces the cost of production. However, grass production is variable during the year, so it is important to use supplementation to fulfil animal requirements. We aimed to determine the effects of different combinations of sward heights and supplementation levels on animal production variables. It was found that pasture management for different heights needs different supplementation levels to attend to animal requirements during the dry season, resulting in great production and probably positive economy to the owner. [ABSTRACT FROM AUTHOR]

The objective was to determine the effect of stockpiled forage type and protein supplementation on VFA production, serum metabolites, and heifer BW. Over 2 yr, spring-born, crossbred heifers (n = 45) were stratified by BW at weaning and randomly assigned to 1 of 3 forage treatments: 1) endophyte-infected tall fescue (TF; Festuca arundinacea), 2) big bluestem (Andropogon gerardi Vitman) and indiangrass (Sorghastrum nutans L.) combination (BI), or 3) switchgrass (SG; Panicum virgatum L.). Forage treatments were then randomly assigned to receive 1 of 2 supplement types: 1) 0.68 kg·heifer-1·d-1 of dried distiller's grains with solubles (DDGS; 28% CP, 74% RUP, and 88% TDN) or 2) 0.22 kg·heifer-1·d-1 of blood meal and fish meal (BF; 72.5% CP, 67.5% RUP, and 69.5% TDN), resulting in a 3 × 2 factorial arrangement of treatments. Treatments were initiated every year in January and terminated in April at the onset of a 60-d breeding season. Body weights and serum samples were collected approximately every 28 d from initiation of grazing until breeding. Serum glucose concentrations were greater (P = 0.05) for heifers grazing SG. Circulating NEFA concentrations were greater (P = 0.04) in TF heifers. Serum urea N (SUN) was not influenced (P = 0.37) by forage type. Ruminal acetate concentration and acetate:propionate ratio were greater (P = 0.04) in heifers grazing SG pastures. Heifer BW change from January to February and overall BW change were greater (P < 0.01) for TF heifers. However, BW change from March to April was not different (P = 0.84) among forage types. Serum glucose and SUN concentrations exhibited (P < 0.05) supplement type × sampling time interactions. Ruminal acetate tended to be greater (P = 0.09) and butyrate concentrations were greater (P < 0.01) for BF-supplemented heifers. The acetate:propionate ratio was not influenced (P = 0.15) by supplement type. Supplement type did not influence (P > 0.13) BW or BW change from January to February and January to April; however, heifers fed DDGS gained (P = 0.03) more BW from March to April. Heifer BW change from February to March exhibited (P < 0.05) a forage type × supplement interaction with BF heifers gaining more BW on BI pastures than DDGS heifers. Overall, developing heifers on low-quality native forages initially delayed BW gain; however, heifers seemed to quickly adapt to the lower-quality forage, resulting in similar BW gains in March and April. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the performance of beef heifers on Stapf. cv. Marandu grass pastures that were managed at three herbage allowances under continuous grazing with a variable stocking rate and were provided with mineral mix supplement or supplements with energy and protein. Seventy-two test heifers and 48 put-and-take heifers were used in a randomised design in a 3 × 2 factorial arrangement [three herbage allowances (1.5, 2.0, and 2.5 kg of green dry matter/kg of bodyweight, and two supplementation levels (mineral mix or 0.3% bodyweight of a mineral-protein-energy supplement)], with two replicates per treatment (paddocks), to maintain the preestablished forage allowance. No significant difference was observed in the gain per hectare as a function of the herbage allowance, but 2.5 kg green dry matter/kg bodyweight provided the greatest average daily gain of bodyweight (0.605 kg/ animal/day). The energy/protein supplementation provided the greatest average daily gain compared with animals fed only the mineral mix. The supplements in the diet of beef heifers fed at 0.3% of bodyweight increased bodyweight gains without compromising the gain per hectare at different herbage allowances. [ABSTRACT FROM AUTHOR]