Interaction of dietary rumen undegradable protein level and supplemental rumen-protected conjugated linoleic acid on performance of growing goat kids

Abstract

Abstract This study aimed to investigate the effects of dietary rumen undegradable protein (RUP) level and supplemental rumen protected conjugated linoleic acid (rpCLA) on performance, nutrient digestibility, rumen fermentation, urinary purine derivatives and plasma metabolites in growing kids. Thirty-two Kurdish kids (13.06 ± 1.08 kg BW) were fed diets differing in RUP level (low = 250 vs. high = 350 g/kg of dietary CP) supplemented either with 15 g/kg rpCLA or 12 g/kg of hydrogenated soybean oil (HSO). The experiment was lasted for 100 days including a 20-d of adaptation period. Goat kids fed diet containing high RUP supplemented with rpCLA had the lowest dry matter intake, but the greatest average daily gain and feed efficiency compared to the other groups (P ≤ 0.05). The interaction of dietary RUP level and rpCLA supplementation had no effect on organic matter, crude protein and ether extract digestibility and ruminal fermentation parameters (P > 0.05). Goat kids fed diet containing high RUP supplemented with HSO had the greatest plasma concentration of triglycerides compared to the other groups (P ≤ 0.05). Urinary uric acid and allantoin concentrations were not influenced by the experimental diets (P > 0.05). In conclusion, feeding diet containing high RUP level supplemented with 15 g/kg rpCLA improved production performance of growing goat kids.