Substituição do milho e farelo de algodão pelo milheto no concentrado da dieta de novilhos em confinamento

Objetivou-se identificar possíveis efeitos da substituição do milho e do farelo de algodão por milheto na digestibilidade dos nutrientes da dieta e no desempenho de bovinos em confinamento. As dietas, com relação volumoso:concentrado 65:35, foram compostas de silagens de milho e milheto como volumoso (50:50, com base na matéria natural) e cinco níveis de milheto em substituição ao milho e ao farelo de algodão (0; 23; 49; 80 e 96% da matéria natural) no concentrado. O delineamento de blocos ao acaso foi adotado em ambos os experimentos. Utilizaram-se cinco repetições no estudo de desempenho e quatro na avaliação do consumo e da digestibilidade in vivo. O consumo de matéria seca (MS) expresso em porcentagem do peso vivo (PV) e g/kgPV0,75, diminuiu linearmente com a introdução de milheto na dieta, registrando-se 2,91% e 108,5 g e, 2,5% e 92,53 g para dietas exclusivas de milho e milheto, respectivamente. As digestibilidades de MS, proteína bruta e carboidratos totais não foram afetadas, enquanto a digestibilidade do extrato etéreo diminuiu e a de fibra aumentou linearmente sem afetar os teores de nutrientes digestíveis totais. O ganho de peso vivo diário, o consumo de MS e a conversão alimentar também não foram afetados pela adição de milheto, portanto, é possível substituir o milho e o farelo de algodão por milheto em rações para bovinos em confinamento.The objective of the present study was to identify possible effects of replacing corn and cottonseed meal by pearl millet on digestibility of nutrients in diets and on performance of cattle in feedlots. Diets with a 65:35 roughage:concentrate ratios were composed of corn and pearl millet silages as roughage (50:50, based on natural matter) and five levels of pearl millet replacing corn and cottonseed meal (0; 23; 49; 80 and 96% natural matter) in the concentrate. It was used random block designs in both experiments. Five replicates were used to evaluate performance and four replicates for evaluating intake and in vivo digestibility. Dry matter (DM) intake, expressed in body weight (BW) percentage and g/kg BW0.75 linearly decreased when pearl millet was introduced into the diet, thus 2.91% and 108.5g and, 2.5% and 92.53 g were registered for diet exclusively with corn and pearl millet, respectively. Digestibility of dry matter, crude protein, and total carbohydrates were not affected, whereas digestibility of ether extract reduced and fiber digestibility linearly increased without affecting contents of total digestible nutrients. Daily body weight gain, dry matter intake and feed conversion were not affected by adition of pearl millet, either, therefore, it is possible to replace corn and cottonseed meal by pearl millet in rations for cattle in feedlot

Meta-analysis of the effects of the dietary inclusion of brewers grains on feed intake, milk yield, and feed efficiency of lactating dairy cows

Distillery byproducts such as brewers grains (BG) have been widely used in dairy cow diets for decades to reduce diet costs and improve nutrient efficiency. Thus, the objective of this study was to evaluate the magnitude of the effects of dietary supplementation with BG on feed intake (DMI), digestibility, milk yield (MY), and feed efficiency (FE) of lactating dairy cows. A total of 12 peer-reviewed articles (n = 472 dairy cows) from 1983 to 2021 were collected systematically with the PRISMA method. The weighted raw mean differences (RMD) between dietary BG and control treatments were estimated with a robust variance estimation. Likewise, diet characteristics, such as CP content, NDF content, type of BG (wet = 1 and dry = 2), DIM, and BG inclusion rate (0 to 75%) were used as covariates in a meta-regression, subset, and dose-response analysis. Compared with the control, dietary BG decreased DMI (19.7 vs. 20.2 kg/d) and tended to increase MY (28.9 vs. 28.4 kg/d), but no effects were observed on FCM yield (29.1 vs. 28.8 kg/d), milk fat (3.8 vs. 3.7%), and milk protein (3.2 vs. 3.2%) concentrations. However, dietary BG increased FE (1.45 vs. 1.34 FCM/DMI) without influencing total-tract DM (61.9 vs. 55.7%) and NDF (49.7 vs. 54.5%) digestibility. Increasing the inclusion rate of BG linearly increased (R2 = 0. 554) dietary NDF. Thus, the dose-response analysis revealed that feeding up to 20% BG (dietary NDF = 39%) to lactating dairy cows increased MY and FE. Overall, this meta-analysis supports the hypothesis that dietary BG improved FE in lactating dairy cows