Dairy Goats’ Responses to Different Levels of Pomegranate By-Product Silage in the Diet: Productive Performance and Metabolic Indicators

The current study evaluated the effects of different levels of inclusion of ensiled pomegranate by-product (PS: 0, 5, 10, and 15% DM) into the diet of lactating dairy goats on production performance and metabolic status. Seventy-two Murciano-Granadina goats were used and balanced split into the four treatments (18 goats/treatment × 4 treatments) and also distributed into two homogeneous batches per treatment to record diet and water ingestion at batch level, according to individual variables (milk yield, body weight, SCC, and parity) obtained in a pre-experimental sampling, when all the variables at the individual (milk yield and composition, body weight, blood) and batch level (DM and water intake) were recorded. Later, the feeding trial was started and conducted for 8 weeks, with body weight, milk yield, and milk composition—fat, crude protein, lactose, milk urea, somatic cell count (SCC)—recorded biweekly. Water intake (WI) and dry matter intake (DMI) were registered weekly over 2 consecutive days. Physiological and oxidative status were reviewed through hemogram, serum biochemical profile, and plasma antioxidant activity at the last sampling. Individual level variables were analyzed using mixed linear models with repeated measures, including diet, sampling, and their interaction as fixed effects, the covariate in the pre-experimental sampling, and the animal and the batch nested to diet as the random effects (PROC GLIMMIX, SAS v9.4). Additionally, observed means and standard deviations of WI and DMI were recorded. The results showed that milk yield and its composition were not significantly (p > 0.05) affected by up to 15 PS inclusion. The statistical differences observed in the hematological and plasma biochemical profiles, as well as in the antioxidant activity, had no practical relevance, as all measured values remained within the established physiological reference ranges. In conclusion, PS can be added to dairy goats diet up to 15% with no evidence of negative effects on production and animal physio-metabolic response during the study period, although longer trials considering complete lactation periods are needed to corroborate these findings.