Substitution of berseem clover with cactus cladodes: effects on growth performance, nutrient utilization, rumen...

Enhancing nutrient use efficiency in ruminants is crucial for achieving economic and environmental sustainability. Utilizing alternative forage sources is a key nutritional strategy to improve ruminant growth performance. This study aimed to evaluate the effect of substituting berseem clover with cactus cladodes in diets of growing goats on feed intake, nutrient digestibility, nitrogen utilization, serum metabolites, rumen fermentation, and growth performance. Substitution levels were 0% (C0), 25% (C25), and 50% (C50) of dietary dry matter (DM). Twenty-one growing Damascus goat kids (initial age 90 ± 8 days; body weight (BW) 17.5 ± 0.29 kg) were randomly assigned by their BW to one of three dietary groups (n = 7 per group) over 120 days. Results showed a linear increase in nutrient intakes (P < 0.05), growth performance (P < 0.001), and feed efficiency (P < 0.001) with increasing cactus inclusion. The C50 group recorded the highest final BW, total weight gain, and average daily gain (P < 0.001), followed by C25 group, and then C0 group. Digestibilities of DM, organic matter, crude protein, neutral detergent fiber, acid detergent fiber, and non-fiber carbohydrates increased linearly (P < 0.05), accompanied by a quadratic increase in CP digestibility (P = 0.001). The C50 and C25 diets showed higher (P < 0.05) digestibility coefficients for these nutrients than C0 diet. Nitrogen intake (P < 0.001), retention (P = 0.008), and retention as a percentage of intake (P = 0.006) increase linearly, with a quadratic increase in nitrogen intake (P = 0.002); values were elevated in C50 and C25 groups relative to C0 group. Ruminal pH (P = 0.002) and ammonia-N concentrations (P = 0.001) declined linearly, whereas total volatile fatty acids increased linearly (P = 0.001). Serum urea also decreased linearly (P = 0.002), with lower levels in C50 and C25 (P = 0.006) than in C0 diet. In conclusion, substituting cactus cladodes for berseem clover in kid diets improved growth performance by increasing nutrient intake, improving nitrogen utilization, and enhancing rumen fermentation.