Dried persimmon peel as a sustainable feed ingredient for goats: Effects on nutrient digestion, energy-nitrogen metabolism, and methane mitigation

This study aimed to evaluate how substituting corn with different proportions of dried persimmon peel (DPP) in a total mixed ration (TMR) affects methane (CH 4 ) production and nutrient digestibility through an in vitro fermentation batch culture system. It was also to investigate its impact on the performance, nutrient digestibility, rumen fermentation, and energy-nitrogen metabolism of goats via an in vivo experiment. Initially, an in vitro experiment was conducted in which 0, 10%, 20%, and 30% corn was replaced with DPP in the TMR to determine the optimum proportion for feeding goats. The results showed that replacing 20% of corn with DPP in the TMR reduced ( P = 0.042) CH 4 (mL/g digestible dry matter [DDM]) without adverse effects on the digestibility of dry matter ( P = 0.708). According to the results of the in vitro batch fermentation experiment, replacing 20% corn with DPP in the diet was selected for the in vivo experiment. In the in vivo study, twelve Guanzhong dairy goats (first-parity, 22 months of age, non-lactating, 53.29 ± 1.92 kg) were divided into two homogeneous groups on the basis of initial body weight. There were six replicates for each treatment, with one goat in each replicate. The dietary treatments in the in vivo study were basal diet (CON) and diet containing DPP (MDPP, 20% of the corn in the basal diet was replaced with DPP on air-dried basis). The experiment lasted 35 d, consisting of a 28-d feeding period and a subsequent 7-d digestion and metabolism trial. The substitution of 20% corn with DPP had no effect on the dry matter intake, average daily gain and apparent total tract digestibility of goats ( P > 0.05). Goats receiving the MDPP diet had lower ( P = 0.012) serum creatinine activity and decreasing trends in aspartate aminotransferase ( P = 0.068), aspartate aminotransferase-to-alanine aminotransferase ratio ( P = 0.073), and blood urea nitrogen ( P = 0.076) than those receiving the CON diet. The inclusion of DPP in diet elevated ( P = 0.046) the catalase activity in serum of goats. The rumen valerate concentration of goats increased when 20% of the corn was replaced with DPP in the diet ( P = 0.034). The rumen acetate concentration ( P = 0.079) and acetate-to-propionate ratio ( P = 0.094) tended to increase when 20% corn was replaced with DPP in the diet. Linear discriminant analysis effect size analysis showed that the relative abundance of g_Izemoplasmatales , g_Moryella , and g_Lachnoclostridium were greater ( P < 0.05) in goats fed the MDPP diet than those in goats fed the CON diet. Compared with goats fed the CON diet, those fed the MDPP diet presented lower ( P < 0.05) relative abundance of g_Eubacterium_ventriosum_group , g_Candidatus_Saccharimonas , g_Tyzzerella , and g_Clostridia_UCG_014 . In conclusion, DPP can replace 20% of the corn in the diet of goats, and has the potential to reduce CH 4 emissions, which has important implications for sustainable livestock production.