Substituição parcial do milho por fontes energéticas para bovinos de corte em pastejo

Abstract

Resumo -O objetivo deste trabalho foi avaliar o efeito da substituição parcial do milho por fontes energéticas alternativas, em suplementos concentrados para bovinos de corte mantidos em pasto de Urochloa brizantha cultivar Marandu, durante o período das águas, no consumo e na digestibilidade aparente total dos alimentos. Foram utilizados cinco bovinos Nelore com peso médio corporal inicial de 367,8±4,31 kg. Utilizou-se o delineamento experimental quadrado latino 5x5, com cinco animais e cinco tratamentos. Foram avaliados: suplementos concentrados isoproteicos, com 30% de proteína bruta, formulados à base de grãos de milho, de milheto e de sorgo, e casca de soja; e um suplemento mineral (controle). Não foram observadas diferenças significativas no consumo de matéria seca (MS) total e de matéria orgânica (MO) entre os animais que receberam suplementação mineral e os que receberam suplementação concentrada; no entanto, estes últimos apresentaram menor (12,28%) consumo de MS de pasto. A suplementação concentrada aumentou o coeficiente de digestibilidade aparente total da MS, da MO, da proteína bruta e dos carboidratos não fibrosos que não foram influenciados pelas fontes de energia. Os grãos de milheto e de sorgo e a casca de soja podem ser utilizados em substituição parcial ao milho, na formulação de suplementos concentrados, sem prejudicar o consumo e a digestibilidade dos nutrientes da dieta.Termos para indexação: Brachiaria brizantha, consumo, digestibilidade, pasto, suplementação concentrada. Partial replacement of corn by energy sources for beef cattle at pastureAbstract -The objective of this work was to evaluate the effect of the partial replacement of corn by alternative energy sources in concentrate supplements for beef cattle kept on Urochloa brizantha cultivar Marandu pasture, during the rainy season, on feed intake and total apparent digestibility. Five Nellore cattle with initial average body weight of 367.8±4.31 kg were used. The experimental design was a 5x5 Latin square, with five animals and five treatments. The following were evaluated: isoproteic concentrate supplements, at 30% crude protein, formulated with corn, millet, and sorghum grains, and soybean hulls; and a mineral supplement (control). No significant differences were observed in total dry matter (DM) and organic matter (OM) intake between the animals fed mineral supplementation and those receiving concentrate supplementation; however, the latter showed the lowest (12.28%) pasture DM intake. Concentrate supplementation increased the coefficient of total apparent digestibility of DM, OM, crude protein, and of non-fiber carbohydrates that were not affected by the energy sources. Millet and sorghum grains, and soybean hulls can be used to partially replace corn in the formulation of concentrate supplements without affecting intake and digestibility of dietary nutrients.

Levels of substitution of corn by soybean hulls in high-concentrate diets for finishing beef heifers

“…By contrast, increases in DMI have been associated with the animal's attempt to elevate its feed intake in order to maintain its energy intake level, given the reduced energy content of diets in which GC was substituted by SH or other by-products. The present results are similar to those obtained by Cardoso et al (2013), who partially substituted corn with alternative energy sources (millet, sorghum, or soybean hulls) in concentrate supplements for beef cattle and found no differences in total DMI, pasture DMI, or in the intake of other nutrients.…”

“…Dry matter intake (DMI) was not changed (P > 0.05) by the levels of SH replacing GC in the concentrate portion of the diet (Table 3) in any of the forms this variable was expressed, averaging 7.83 kg/day, 2.51% BW, and 1.86 g/kg of metabolic weight (MW). These results are in line with most findings reported in the literature (Cardoso et al, 2013;Freitas et al, 2013) but disagree with some in which DMI declined (Ranathunga, Kalscheur, Hippen, & Schingoethe, 2010;Mohammadzadeh, Rezayazdi, & Nikkhah, 2014) or increased as the starch from corn was substituted by the digestible fibre from SH in ruminant diets. 1 kg/day; 2 % of body weight (BW); 3 g/kg of metabolic weight (MW); 4 -Probability for the orthogonal contrasts: L -linear (0 -1 0 1) and Q -quadratic (0 -1 2 -1) effects of SH inclusion as a substitute for GC; CP, kg/day = 1.32 + 0.0015SH, R 2 = 0.52; CP, % BW = 0.412 + 0.00071SH, R 2 = 0.63; CP, g/kg MW = 0.31 + 0.00041SH, R 2 = 0.61; NDF, kg/day = 1.11 + 0.027SH, R 2 = 0.99; NDF, % BW = 0.365 + 0.0008SH; R 2 = 0.88; NDF, g/kg MW = 0.261 + 0.0065SH; R 2 = 0.99; TDN, kg/day = 5.67 -0.0011SH; R 2 = 0.57; TDN, g/kg MW = 71.14 -0.036SH + 0.00046SH; R 2 = 0.42; SEM = standard error of the mean.…”

“…This 'compensates' for the lower energy content of this ingredient compared to ground corn. However, most studies supporting this hypothesis investigated the substitution of corn by soybean hulls in low-to medium-concentrate diets Mueller & Boggs, 2011;Cardoso et al, 2013;Freitas et al, 2013) and thus, the potential of this feedstuff in high-concentrate diets is still poorly understood. This is especially true for female cattle, which constituted 46.6% of the total cattle slaughtered in the first quarter of 2018 in Brazil (Instituto Brasileiro de Geografia e Estatísticas [IBGE], 2018).…”

Supplementation strategies for grazing beef cattle during the rainy-dry transition period

“…A possible explanation for the lack of effects on NDF digestibility in steers receiving protein supplements during the rainy-dry transition (CARDOSO et al, 2013) could be in part the greater rumen available N supply (OLSON et al, 1999), which increased the rumen particulate passage rate and consequently reduced the time rumen microorganisms had access to the substrate (CAPPELLOZZA et al, 2013). The positive response of forage intake and nitrogen use efficiency to concentrate supplementation is due to some improvements in digestibility; nevertheless, the main benefit of supplementation is based on the improvement of the nitrogen status in the animal metabolism (DETMANN et al, 2014).…”

Pearl millet grain for beef cattle in crop-livestock integration system: intake and digestibility

“…In fact, Cardoso et al (2013) and Nascimento et al (2009) observed no effects associated with different energy sources in protein-energy supplements on total DM and grazing DM intake in grazing cattle. Similarly, Silva et al (2014) observed that pearl millet grain could fully replace maize in high supplement diets for confined cattle.…”