Nutrient Intake, Performance, Carcass Characteristics, Meat Quality, and Cost Analysis of Sheep Submitted to Intermittent Supplementation on Masai Grass Pastures.

This study aimed to assess nutrient intake, performance, intake behavior, carcass characteristics, and meat quality of sheep managed on Masai grass pastures along with intermittent concentrate supplementation, in addition to the economic impacts of applying that strategy. A sample of 24 Santa Inês sheep (12 males and 12 females) was kept for 80 days on Panicum maximum cv. Massai pastures and was supplemented daily or every other day. The voluntary intake of dry matter and nutrients was estimated. Mean daily weight gain and total weight gain were calculated and intake behavior parameters were assessed. The males were slaughtered and the weight and yield of the carcasses and meat cuts were assessed. The meat was analyzed for cooking losses, shear force, and color. The gross margin of the system was estimated from the difference between total income and operational cost. No effect was seen of the interaction between supplementation frequency and sex for any parameter assessed (p > 0.05). Intermittent supplementation of Santa Inês sheep managed with Masai grass is recommended since the strategy does not impact nutrient intake, performance, intake behavior, carcass characteristics, or meat quality, but lowers the costs of producing 1 kg of meat by 15%.

Prediction of weaning weight in Santa Inês lambs using the body volume formula.

Weaning weight (WW) is one of the most important information within production systems, as it is a reflection of management during the breastfeeding phase and will influence the performance of animals in subsequent phases. This study aimed to develop and evaluate linear, quadratic, and exponential models to predict WW using the body volume (BV) formula in Santa Inês lambs for meat. Eighty-five lambs at 90 days of age with WW 17.52 ± 3.79 kg and BV 13.29 ± 2.86 dm3 were evaluated. The quality of fit of the models was evaluated using the coefficient of determination (R2), mean squared error (MSE), and root MSE (RMSE). For the external evaluation of the models, an independent dataset from 43 lambs at 90 days of age was used. The first-degree linear model showed the lowest values of MSE (1.02) and RMSE (1.01). In the external evaluation, all models exhibited estimates of mean WW and standard deviation of this weight similar to the external dataset, as well as high values (above 0.89) for the R2 of predicted vs. observed data. Concordance correlation coefficient (CCC) analysis also revealed that all models showed accuracy and precision (CCC > 0.90). There was no difference between the models in terms of accuracy (P > 0.05). The comparison in terms of precision indicated that the linear model is more precise than the exponential model and that the quadratic model is as precise as the linear model. The first-degree linear model should be used due to its simplicity of interpretation and ease of estimation.

Prediction of dry matter intake by meat sheep on tropical pastures.

This study was undertaken to determine whether equations for prediction of dry matter intake (DMI) by meat sheep are valid for animals raised solely on tropical pastures and to propose a new equation to predict the DMI of sheep raised on tropical pastures. The DMI prediction from published equations was evaluated by regressing the predicted and observed values, using the F test, for the identity of the parameters (ß0 = 0 and ß1 = 1) of the regression of predicted on observed data. If the null hypothesis is not rejected, the tested equation accurately estimates DMI. The proposed equation was evaluated in the same way as the published equations. The animal performance and pasture structure and chemical composition data used originated from an experiment conducted with 32 Santa Inês sheep raised on tropical pastures. In the analysis of model adequacy, the null hypothesis was rejected (P < 0.001) and the equations generated predictions that differ (ß0 = 0 and ß1 = 1) from the DMI observed under practical feeding conditions for grazing sheep. The proposed equation, DMI (%LW) = 7.16545 (± 0.76522) - 0.21799 (± 0.01812) * LW + 0.00273 (± 0.00034) * LW2-0.00688 (± 0.00299) * GT + 0.000007 (± 0.000002) * GT2 + 0.00271 (± 0.00108) * GHA, where LW is live weight (kg), GT is grazing time (min/day), and GHA is green herbage allowance (kg DM/100 kg LW), should be used to more accurately predict DMI by grazing sheep.

Biometric measurements of Santa Inês meat sheep reared on Brachiaria brizantha pastures in Northeast Brazil.

This study was undertaken to examine biometric measurements during the growth phase of male and female Santa Inês sheep reared in Brachiaria brizantha pastures in northeastern Brazil. The experiment involved 24 castrated males and 24 females at an initial age of 90 days, with an average body weight of 19.04 ± 0.96 kg. Treatments consisted of the effect of four cultivars (Marandu, Xaraés, Piatã and Paiaguás) and two sexes. Six animals were used per treatment, in a randomized-block experimental design. The following characteristics were evaluated: abdominal circumference (AC), body condition score (BCS), body length (BL), body weight (BW), body capacity 1 (BC1), body capacity 2 (BC2), chest width (CW), heart girth (HG), leg circumference (LC), leg length (LL), rump height (RH), rump width (RW) and withers height (WH). Data were subjected to descriptive analysis, Pearson's correlation, ANOVA and Tukey's, Kruskal Wallis and Mann-Whitney tests. Univariate and multiple regressions were applied to estimate BW with a maximum error level of 5%. Significant differences were observed for the biometric measurements between sexes and cultivars (p<0.05). Body weight was highly correlated (>70%) with AC, WH, CG, RW, BC1 and BC2. The male sheep grazed on cultivars Piatã showed the best values for BW (40.43 kg), HG, RW, WH, LL, LC (102.46; 20.8; 65.23; 60.44; 42.54 cm respectively) and BC1 (4.25 kg/cm). Females grazed on cultivar Marandu had higher values for RW, CW, LL (17.26; 20.1; 75.98 cm respectively), BC1 (6.03 kg/cm) and BC2 (0.422 kg/cm). The equations that best estimated live weight were BC1 and HG. In male and female Santa Inês sheep, biometric parameters grow differently depending on the cultivar where they are grazed during the growth phase. Cultivars Marandu and Piatã are the most recommended for sheep production, as they provided the best performance and body development in those animals.

β-mannanase and mannan oligosaccharides in broiler chicken feed / β-mananase e mananoligossacarídeo em rações de frangos de corte

The study aimed to evaluate the use of β-mannanase and mannan oligosaccharides (MOS) to replace growth promoters in broiler diets. Four hundred male Cobb broiler chicks were used, with initial weight of 45±1g, distributed in a completely randomized design with five treatments and eight repetitions of ten birds. The treatments were: basal feed; basal feed without growth promoter; basal feed without growth promoter + β-mannanase; basal feed without growth promoter + MOS; and basal feed without growth promoter + β-mannanase + MOS. The feed intake of the birds increased in response to dietary treatments compared to basal diet during the period 1-21 days of age. A higher weight gain and improved feed conversion was found at 42 days of age among birds that had received the basal diet without growth promoter + MOS. The absolute weight at slaughter, relative carcass and prime cuts except breast weights improved in response to dietary treatments compared to the basal diet at 42 days of age. No difference was observed in relative weight of the liver, while significant differences were found in the weight of heart, gizzard, and abdominal fat. It was concluded that β-mannanase and MOS can replace the growth promoters in broiler diets without compromising production and economic performance. However, the association of these products into the feed may cause negative interaction that reduces the broiler chickens' performance.

O experimento teve como objetivo avaliar a utilização de β-mananase e mananoligossacarídeos em substituição aos promotores de crescimento nas rações para frangos de corte. Foram utilizados 400 pintos de corte machos da marca Cobb, com peso inicial de 45±1g, distribuídos em delineamento inteiramente ao acaso, com cinco tratamentos e oito repetições de 10 aves. Os tratamentos foram: ração basal; ração basal sem promotor de crescimento; ração basal sem promotor de crescimento + β-mananase; ração basal sem promotor de crescimento + MOS; e ração basal sem promotor de crescimento + β-mananase + MOS. O consumo de ração das aves aumentou em resposta aos tratamentos dietéticos, quando comparados à ração basal no período de 1 a 21 dias de idade. Observou-se maior ganho de peso e melhora na conversão alimentar das aves aos 42 dias de idade que receberam a dieta basal sem promotor de crescimento + MOS. Os pesos absolutos ao abate e relativos de carcaça e de cortes nobres, com exceção de peito, melhoraram em resposta aos tratamentos dietéticos, quando comparados à ração basal aos 42 dias de idade. Não houve diferença sobre o peso relativo de fígado, enquanto os pesos de coração, moela e gordura abdominal foram influenciados pelos tratamentos. Concluiu-se que a β-mananase e o MOS podem substituir os promotores de crescimento em rações de frangos de corte sem comprometer o desempenho produtivo e econômico, no entanto, a associação destes produtos à ração pode causar interação, reduzindo o desempenho das aves.