Dietary supplementation improves animal performance and reduces methane emission intensity in young llamas grazing natural forages

Abstract

The aim of this study was to evaluate the effects of concentrate supplementation on animal performance, enteric methane (CH₄) emissions, and forestomach (C1-C2 and C3) fermentative parameters of young llamas grazing on natural forage. Eighteen male llamas were assigned to two treatments, with 9 animals per treatment. The treatments were forage (F) with free access to natural grassland primarily composed of Festuca spp., and F plus supplement (FS). Supplementation with ground corn and soybean expeller (80:20 ratio on DM basis) was 1.5 % based on body weight for 35 days. The total dry matter intake (DMI), CH₄ emissions (g/d), and CH₄ yield (g/kg DMI) did not differ between diets. However, CH₄ intensity (g/kg average daily gain) was significantly reduced (-48 %) in FS than in the F diet. The pH, total volatile fatty acids, and ammonia nitrogen concentrations in the C1-C2 did not differ between diets. However, the proportion of acetate and the acetate to propionate ratio decreased but propionate and butyrate were increased in the FS than in the F diet (P < 0.05). Whereas in C3, only butyrate increased in the FS diet than in the F diet (P < 0.05). Total bacteria and methanogen populations did not differ between treatments. Nevertheless, in C1-C2 and C3, the abundance of protozoa did differ statistically (P = 0.041 and P = 0.046, respectively), in the FS diet than in the F diet. In conclusion, concentrate supplementation increased propionate and butyrate proportions of forestomach contents which lead to improve animal performance and reduced CH₄ emission intensity.