Comparative Effects of C3 and C4 Forages on Growth Performance, Digestibility, and Nitrogen Balance in Korean Crossbred Black Goats

This study compared the effects of two C3 forages (Italian ryegrass [RG], Timothy grass [TG]) and two C4 forages (Klein grass [KG], Bermuda grass [BG]) on growth performance, nutrient digestibility, and nitrogen (N) balance in Korean crossbred black goats to evaluate C4 warm-season forages as alternatives under changing climate conditions. Sixteen castrated goats (10 months old) were allocated to four treatments using a randomized complete block design. Diets contained 40% treatment-specific forage and 60% commercial concentrate. After adaptation periods, a 5-day metabolism trial measured performance and digestibility parameters. No significant differences occurred among treatments for growth performance or digestibility of dry matter, crude protein, neutral detergent fiber, ash, and non-fiber carbohydrate. C4 grasses showed significantly lower acid detergent fiber and ether extract digestibility than C3 grasses, with KG having the lowest ether extract digestibility. The KG group had higher N intake and absorption than the TG group, while BG showed lower urinary and total N excretion than KG. No differences existed in retained N, utilization efficiency, or biological value among groups. Both C3 and C4 forages supported comparable goat growth performance, providing a reference for utilizing different photosynthetic pathway forages under changing climatic conditions.