Performance and nutrient utilization in purebred Spanish and Boer × Spanish and Kiko × Spanish genetic types of goats offered alfalfa hay with corn supplementation

A metabolism (Experiment 1; n = 18) and a pen feeding (Experiment 2; n = 24) study were conducted to determine dry matter intake (DMI); in vivo dry matter (DM), organic matter (OM), nitrogen (N), neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibility, N use, and performance of three genetic types of meat goats offered high forage diets. In both experiments, 7 mo old castrate male goat kids, equally representing the F1 Boer × Spanish (BoerX; avg wt 21 kg), Kiko × Spanish (KikoX; avg wt 26 kg) and Spanish (avg wt 20 kg) genetic types, were offered chopped alfalfa (Medicago sativa L.) hay with an 80% corn (Zea mays L.)-18% soybean [Glycine max (L.) Merr.] meal supplement. In Exp. 1, goats were offered alfalfa hay plus supplement at 0.5% BW. Total DMI hay intake among the three breed types was variable, but was higher (P = 0.05) for KikoX compared to Spanish; BoerX was intermediate. Apparent in vivo digestibility coefficients for DM, OM, N, NDF, and ADF were not different (P > 0.10). Blood glucose concentrations were similar for Spanish and KikoX (mean 70.3 mg/dl), but both were higher (P < 0.01) compared to BoerX (62.6 mg/dl). In Exp. 2, goats were offered alfalfa hay plus the same supplement at 2% BW. Hay DMI (mean 2.46% BW) and total DMI (mean 4.26% BW) were not different among genetic types. Beginning and ending BW were greater (P < 0.001) for KikoX compared to BoerX; both were greater than Spanish, but ADG were similar (P > 0.10) among breeds (93 g/d). More research is needed that evaluates forage-supplement interactions, metabolic differences, and physiological changes among meat goats in order to optimize nutrient-use efficiency and performance.