Fresh sugarcane has been a new roughage source for ruminant's in semiarid regions, a function of the decline of sugar and alcohol industry in recent years. However, there is little data published regarding lambs fed sugarcane associated with spineless cactus. This study evaluated the effect of sugarcane replacement with spineless cactus (0%, 33%, 66%, and 100%) in the diet of Santa Inês lambs on carcass characteristics. Thirty-six non-castrated Santa Ines lambs at four months of age and an initial body weight of 22±2.3 kg were assigned in a randomized block design and slaughtered after 70 days of confinement. The effects of spineless cactus as a replacement for sugarcane in the diet of the lambs on the carcass characteristics, commercial cut weight and yield, leg tissue composition, and carcass measurements were studied. The study revealed quadratic behavior in slaughter body weight, and hot and cold carcass weight, with maximum values of 38.60, 18.60, and 18.11 kg and replacement levels of 40.18%, 44.42%, and 43.14%, respectively. The cold carcass yield presented an increasing linear behavior. The compactness index of carcass and leg presented a quadratic effect, with estimated maximal values of 0.28 and 0.57 kg/cm and replacement levels of 43.37% and 45.5%, respectively. The weights of commercial cuts of leg, loin, shoulder, and breast showed quadratic behavior, with maximum values of 2.79, 0.852, 1.46, and 1.30 kg and replacement levels of 49.5, 45.32, 39.0, and 40.7, respectively. For tissue composition, quadratic behavior was verified for leg weight, subcutaneous fat, and total fat. The replacement of sugarcane by spineless cactus at level 44% is recommended for finishing lambs considering that this level improved most of the carcass characteristics, weights, and yields of commercial cuts and leg tissue composition.

The aim of this study was to compare the gas production profiles and nutrient degradability of two diets using automatic and semiautomatic in vitro gas production techniques. A randomized block design in a 2 × 2 factorial arrangement was adopted, with two diets comprising different proportions of nonfiber carbohydrates (NFCs) (low-NFC vs. high-NFC diets), two gas production measurement techniques (automatic vs. semiautomatic) and four replicates. The blocks represent three in vitro runs. Gas production from the fermentation of fiber carbohydrates (Vf2) was 22% higher when measured with the automatic technique than with the semiautomatic technique. The Vt of the low-NFC diet differed between techniques and was 22.9% higher using the automatic technique. A highly positive correlation (r = 0.96) was observed between the techniques, with a high coefficient of determination between the techniques (R² = 0.93). There was greater degradability of dry matter (DMD) and organic matter (OMD) with the automatic technique. In both diets, the degradability of crude protein (CPD) was greater with the semiautomatic technique (p < 0.0001). The high-NFC diet resulted in a lower pH and lower NH₃-N in the incubation medium than in that of the low-NFC diet, whereas the degradability of DM, OM and CP increased. The automatic and semi-automatic techniques similarly estimated the kinetic parameters and the profiles of total gas production, demonstrating the potential of both techniques for assessing the nutritional value of diets with different proportions of NFCs.

Thirty-five feedlot lambs (without defined breed, aged between 5 and 7 months, with average live weight of 17.7±3.7 kg) were used in a completely randomized design to evaluate the effect of diets containing different genotypes of sorghum on morphometric measurements and qualitative characteristics of carcass and yields of primal cuts. The animals stayed in individual indoor pens for 42 days and slaughtered at an average weight of 26.24 kg. No significant differences were observed on morphometric measurements, hot (11.67 kg) and cold (11.39 kg) carcass weight, hot (44.46%) and cold (43.37%) carcass yields, biological yield and on cooling losses. There was also no significant effect of silages of different genotypes of sorghum on the weights and yields of retail cuts (neck, shoulder, rib, loin and leg) and on the subjective evaluation of carcasses. It is possible to finish sheep without defined breed feeding them diets based on silages of sorghum, resulting in carcasses with high yield and good conformation

Nos sistemas de produção de ruminantes a alimentação pode responder por 60 a 70% dos custos da atividade, sendo assim, a avaliação nutricional dos alimentos e a formulação de dietas balanceadas, que atendam às exigências dos animais representam um importante desafio na produção pecuária. Diversos métodos têm sido usados para avaliar a modulação da fermentação ruminal e estimar as características da degradação de alimentos e dietas destinadas à alimentação de ruminantes. Esses métodos envolvem a medição do desaparecimento do substrato durante a incubação no rúmen in situ, no líquido ruminal tamponado (in vitro) e são principalmente medidas de ponto final. Além disso, é possível avaliar a cinética da degradação através da medição das diferenças nos resíduos em diferentes tempos de incubação. A avaliação do valor nutricional de alimentos e dietas também é possível ser feita por meio da utilização de técnicas que medem a produção de gás. Essas técnicas medem o aparecimento de produtos da fermentação ruminal, tais como os gases dióxido de carbono (CO2) e metano (CH4), ácidos graxos de cadeia curta, amônia e a biomassa microbiana. Objetivou-se com essa revisão descrever os principais métodos in situ e in vitro utilizados para avaliar alimentos para ruminantes.