Residual feed intake and gain alters the performance and carcass traits in Nellore cattle.

The residual intake and gain (RIG) aims to select animals that present low feed intake in relation to the expected. This study aimed to evaluate the associations of selection for RIG with performance and carcass traits in Nellore cattle. Initially, residual feed intake (RFI) and residual gain (RG) were determined. From this, the RIG was calculated, and the animals were classified as efficient and inefficient for RIG. The efficient animals for RIG showed higher daily weight gain (DWG), Longissimus muscle area (LMA), and mid-test metabolic body weight (MMBW) than the inefficient ones. No significant correlations were found between subcutaneous fat thickness (SFT), marbling (MAR), LMA, MMBW, and the RIG. Thus, it's concluded that the RIG is a measure that can be used to identify and select animals with higher rates of DWG and LMA without changes in the dry matter intake (DMI), SFT, and MAR. However, this index should still be observed with caution, as it may be dependent on body size. Based on the findings, the selection of animals according to the RIG can be an important factor to generate phenotypic evolution in characteristics such as weight gain and rib eye area without adverse effects on the carcass fat deposition.

Enzimas exógenas na dieta de leitões desmamados / Exogenous enzymes in the diet of weaned piglets

O desmame é caracterizado como o período mais crítico da produção de suínos devido à imaturidade digestiva e à baixa concentração de enzimas digestivas, como carboidrases, proteases e fitases, nas primeiras semanas do pós-desmame, o que ocasiona o baixo desempenho dos leitões. Neste caso, há a necessidade de suplementação exógena de enzimas que atuam na degradação de frações do alimento, aumentando o aproveitamento da dieta. A nutrição enzimática exógena tem sido considerada uma alternativa eficaz frente à baixa concentração de enzimas endógenas nas primeiras semanas após o desmame por contribuir para o aumento na digestibilidade das dietas sólidas e, deste modo, para um maior aproveitamento dos ingredientes. Na nutrição de suínos, as enzimas exógenas mais utilizadas são as carboidrases, as proteases e as fitases. Ademais, a utilização de blends enzimáticos também é considerada uma ótima alternativa, pois contribui para a inibição de fatores antinutricionais, os quais são responsáveis por indisponibilizar nutrientes necessários para o desenvolvimento e desempenho dos animais. Diante do exposto, o objetivo deste estudo foi apresentar as principais enzimas exógenas utilizadas na nutrição de leitões desmamados, bem como seus efeitos no desempenho animal.

Weaning is characterized as the most critical period in swine production due to digestive immaturity and low concentration of digestive enzymes, such as carbohydrases, proteases, and phytases, in the first weeks after weaning, which causes poor performance of piglets. In this case, there is the need for exogenous supplementation of enzymes that act on the degradation of food fractions, increasing diet utilization. Exogenous enzyme nutrition has been considered an effective alternative to the low concentration of endogenous enzymes in the first weeks after weaning, as it contributes to an increase in the digestibility of solid diets and, consequently, greater use of the ingredients. In swine nutrition, the most used exogenous enzymes are carbohydrases, proteases, and phytases. Furthermore, the use of enzymatic blends is also considered a great alternative, as they contribute to the inhibition of anti-nutritional factors, which are responsible for making nutrients necessary for the development and performance of animals unavailable. Therefore, this study aimed to present the main exogenous enzymes used in the nutrition of weaned piglets, as well as their effects on animal performance.