Serum Amino Acid Profile and Nitrogen Balance in Goats Fed Varying Ratios of Roughage to Concentrate Under Semi-Arid Conditions in Kano State, North West Nigeria

Nitrogen utilisation efficiency and amino acid availability determine productive performance in goats under the resource-constrained feeding systems prevalent in semi-arid northern Nigeria. The relationship between dietary roughage-to-concentrate ratio and serum amino acid profiles in Nigerian goats under field conditions has not been empirically established. This study analysed serum amino acid profiles and nitrogen balance in Red Sokoto goats fed four roughage-to-concentrate ratios (100:0, 70:30, 50:50, and 30:70) over a twelve-week trial in Kano State. Sixty animals in four groups of fifteen each were offered weighed rations under metabolism cage conditions during two metabolic collection periods. Serum amino acid concentrations were determined by high-performance liquid chromatography. Total nitrogen intake, faecal nitrogen, and urinary nitrogen were measured to calculate nitrogen balance. The 50:50 group achieved the highest nitrogen retention and positive nitrogen balance with superior serum concentrations of essential amino acids including lysine, methionine, and threonine. The 30:70 group showed increased urinary nitrogen excretion without proportionate improvement in serum essential amino acids, suggesting inefficient nitrogen utilisation at high concentrate inputs. The 100:0 roughage-only group recorded negative nitrogen balance. Body weight gain correlated positively with nitrogen balance across all groups. These findings provide empirical guidance for optimising roughage-to-concentrate ratios in semi-arid Nigerian goat production to maximise nitrogen utilisation and growth. Keywords: amino acid profile, nitrogen balance, roughage-concentrate ratio, goats, Kano State.