Bagaço de cana-de-açúcar e feno de capim-elefante em dietas para caprinos castrados e não castrados terminados em confinamento

Abstract

The objective of this study was to evaluate the performance, intake and digestibility of nutrients, ingestive behavior and carcass characteristics of dairy goats male kept in confinement. Twenty-four animals (12 not castrated and 12 castrated) were used, with a mean initial weight of 18.5 ± 3.8 kg, fed for 70 days with forage palm-based diets receiving sugarcane bagasse (PBCA) or elephant grass hay (PFCE) as fiber sources with diets formulated to possess similar amounts of neutral detergent fiber (NDF). The experimental design was completely randomized in a 2 x 2 factorial arrangement, with two sexual conditions, two fiber sources and six replicates per treatment, totaling 24 plots.. There were no statistically significant differences in dry matter intake (CDM), crude protein consumption (CCP) and NDF consumption (CNDF), with averages of 567 and 670 g/ day, 78 and 88 g/ day, and 219 and 258 kg/ day for the PBCA and PFCE, respectively. However, higher intakes of non-fibrous carbohydrates (CNFC) were observed in the animals that consumed the diet containing elephantgrass hay (247 g/ day). The highest coefficients of digestibility for dry matter (DDM), crude protein (DCP) and non-fibrous carbohydrate (DNFC) were found for PBCA treatment, with averages of 66.12, 74.26 and 91.94%, respectively, when compared to 62.88, 70.95 and 83.07%, respectively, for the PFCE. The digestibility of NDF did not vary according to the treatments. There were interaction effects for the consumption of total digestible nutrients (TDN), with higher results for the not castrated animals that consumed the PFCE diet (471 g/ day). Regarding performance, no differences were detected for the analyzed variables, with mean values for final weight (FW) of 22.40 and 22.95 kg, mean daily gain (MDG) 55 and 71 g/ day, total gain TG) 3.89 and 4.92 kg and feed conversion (FC) of 11.59 and 10.02 for the PBCA and PFCE treatments, respectively. In relation to the ingestive behavior, there was difference for the idle times, rumination and total chewing time, with mean times of 1812.20 and 1539.00 minutes, 865.62 and 1100.58 minutes, 202.17 and 240.43 minutes, respectively for PBCA and PFCE, but there was no effect for feed and rumination efficiencies evaluated. Regarding the carcass characteristics, statistical differences were observed for carcass weight hot (WCH) and cold carcass weight (CCW), with averages of 9.87 and 10.79 kg, 9.69 and 10.52 kg, for PBCA and PFCE, respectively, and for the carcass yields hot (CYH), commercial yield (CY) and biological yield (BY), with averages of 43.81 and 46.87%, 42.90 and 45.73%, and 55.32 and 59.76% for PBCA and PFCE, respectively. The final weight (FW), empty body weight (EBW), pH and carcass temperature were not statistically diferente. There was an effect of the sexual condition for WCH and CCW, with averages of 10.80 and 9.86 kg and 10.56 and 9.64 kg, respectively, for not castrates and castrates, respectively, as well as significant interaction between the sources of variation, with higher values of the not castrated animals o of the PFCE treatment, with averages of 11.76 and 11.48 kg for WCH and CCW, respectively. In relation to the meat cuts, diet had an influence on the weight of the leg (1,526 and 1,679 kg, for the treatments PBCA and PFCE, respectively), as well as effect of the sexual condition on the weights of neck and ribs, with averages of 654 and 500 g and 900 g and 752 g for not castrated and castrated animals, respectively, as well as weigth neck yield for not castrated animals (11.91%). Morphometric measures were influenced by diet, with a mean for the carcass compactness index being 0.160 and 0.173, respectively for PBCA and PFCE treatments, with significant interaction and larger measurements for not castrated animals that consumed the hay-based diet of Elephant grass (0.18). The weights and yields of the “buchada” and “panelada” were not altered. It is recommended, as an alternative for the confinement of dairy goats, the use of elephantgrass hay associated with forage palm, without applying the practice of castration.