Ingestive behavior, intake and digestibility of nutrients, and water and nitrogen balance of lactating goats fed dehydrated grape pomace

The use of agro-industrial waste as feed for dairy goats allows farmers to integrate alternative sources with conventional feeds. This study aimed to assess the ingestive behavior, intake, nutrient digestibility, and water and nitrogen balance in lactating Saanen goats. Eight multiparous Saanen goats, approximately four years old and weighing an average of 41.2±5.57 kg of body weight (BW; mean ± standard error of the mean), were included in a double Latin square (4×4) design. The treatments consisted of partially replacing the cactus pear with dehydrated grape pomace at 0, 90, 150, and 210 g/kg levels based on dry matter (DM). The diets were isoproteic (151 g/kg of crude protein; DM) and had a 60:40 roughage:concentrate ratio. Ingestive behavior was evaluated through visual observations. Samples of the ingredients, leftovers, and feces were analyzed to determine the content of DM, crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, and ash. The total feces production was used to determine indigestible neutral detergent fiber (NDFi). Water intake was measured to assess the water balance. The nitrogen balance was calculated using urine and feces. The data were subjected to analysis of variance (ANOVA) and linear and quadratic regression at a significance level of 5%. Rumination time and neutral detergent fiber intake efficiency increased (30.4%; P = 0.001 and 46.9%; P = 0.046, respectively), while idling time decreased (12.3%; P = 0.008) with the inclusion of 210 g/kg of pomace. The digestibility of the crude protein decreased (51.4%; P < 0.001) at the highest pomace level. A quadratic effect (P = 0.008) on fecal N was observed with highest value estimated to 175 g/kg of pomace. Milk urea N increased (55.6%; P = 0.016) at 210 g/kg of pomace. In conclusion, replacing cactus pear with dehydrated grape pomace in the diet of lactating goats increased the intake. Still, it reduced the digestibility of certain nutrients and led to greater N excretion through feces and milk.