Metabolismo energético de cordeiros inoculados com fungos celulolíticos e alimentados com torta de macaúba

Abstract

The aim of this study was to evaluate the intake, nutrient digestibility, and energy metabolism in lambs fed with non-additive or additive macauba cake with autochthonous cellulolytic fungi. Eighteen crossbred, non-castrated male lambs were evaluated and distributed into three experimental groups: control diet (CTRL), diet with macauba cake (MC), and diet with macauba cake and autochthonous cellulolytic fungi (TM+ACF). The animals were adapted to the experimental conditions of the digestibility trial for 15 days, during which they remained in metabolic cages and were fed twice a day. After adaptation, diets, leftovers, feces, and urine were measured and sampled daily for five days to determine the intake and digestibility of dry matter (DM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), acid detergent fiber (ADF), and non-fiber carbohydrates (NFC). Subsequently, a respirometry trial was conducted, during which the animals were individually transferred to a small ruminant respirometric chamber. Oxygen consumption and carbon dioxide and methane production were measured for 20 hours/animal, with measurements taken while the animals were fed and subsequently fasting. Data were subjected to analysis of variance, and means were compared by Tukey's test at a 5% probability level. There was no difference in dry matter (DM), crude protein (CP), and mineral matter (MM) intake, with means of 1258.43, 256.75, and 101.87 g/day, respectively. Ether extract (EE), neutral detergent fiber (NDF), and acid detergent fiber (ADF) intake were higher (P<0.05) in animals fed with the diet containing macauba cake, with respective values of 61.0, 553.34, and 355.20 g/day. Animals fed with the CTRL diet had higher (P<0.05) non-fibrous carbohydrate (NFC) intake (539.44 g/day). In animals fed with the CTRL diet, DM (69.20%) and NDF (59.51%) digestibility were higher (P<0.05) than in the other groups (mean of 59.51% and 43.59%, respectively). The digestible energy intake was lower in the MC and MC+ACF (280.34 and 257.04 kcal/kg BW0.75/day) than in the CTRL (306.80 kcal/kg BW0.75/day), due to a higher percentage of energy loss in feces. Metabolizable energy consumption and net energy were similar among the evaluated animal groups, with means of 245.51 and 179.85 kcal/kg BW0.75/day, respectively. It is concluded that the inclusion of macauba cake in the diet reduces diet digestibility; however, it does not alter animal intake and energy utilization. Additionally, the use of fungal aditives does not result in improved diet utilization.