Digestibility and nitrogen retention in llamas and goats fed alfalfa, C3 grass, and C4 grass hays

• Published in: Small ruminant research Vol. 64; no. 1-2; pp. 162 - 168
• Main Authors: Robinson, T.F, Sponheimer, M, Roeder, B.L, Passey, B, Cerling, T.E, Dearing, M.D, Ehleringer, J.R
• Format: Journal Article
• Language: English
• Published: 01.07.2006
• Subjects: alfalfa; animal feeding; body weight; C3 plants; C4 plants; digestibility; dry matter intake; excretion; feces; forage grasses; goats; hay; llamas; nitrogen; nitrogen balance; nutrient retention; urine
• ISSN: 0921-4488; 1879-0941
• DOI: 10.1016/j.smallrumres.2005.04.018

The objective of this experiment was to determine the relative digestive capabilities and N retention between goats and llamas fed three forages. Four llamas (2 yrs; 125 ± 7.3 kg BW) and four Boer-cross goats (2 yrs; 53 ± 8.4 kg BW) were housed in metabolism crates and fed alfalfa (Medicago sativa; ALF), temperate C3 grass (Festuca arundinacea; C3G) and tropical C4 grass (Cynodon dactylon; C4G) hays. Each forage was fed for 21 d during which time the animals were adapted to the forage, followed by a 5 d period of urine and feces sample collection. Dry matter intake species differences, when adjusted to metabolic body weight (kg BW0.75; MW), were noted for ALF and C3G (P < 0.01), while the goats showed a difference between all three forages (P < 0.05; 61.6, 31.0 and 46.2 g/(d kg0.75) for ALF, C3G and C4G, respectively), the llamas showed a difference between the grasses (40.4, 52.1 and 38.5 g/(d kg0.75) for ALF, C3G and C4G, respectively). Digestible DM relative to MW (DDM/MW) was higher for ALF and C4G for the goats versus the llamas (P < 0.03; 42.5 and 29.0 g/(d kg0.75) for goat ALF and C4G and 27.9 and 23.2 g/(d kg0.75) for the llama ALF and C4G, respectively). Llamas had a higher DDM/MW for the C3G, 19.6 and 28.9 g/(d kg0.75) than goats. Both animal species were in positive N balance for all three forages; llamas and goats retained more N on the high-protein ALF, 0.60 and 0.22 g/(d kg0.75), respectively, than they did on either of the grasses (P < 0.05; 0.15 and 0.04 g/(d kg0.75) for C3G and 0.35 and 0.14 g/(d kg0.75) for C4G). Unexpectedly, however, both species retained more N on C4G than on C3G. These results demonstrate that, under these circumstances, llamas do not have a higher digestive efficiency than goats, and goats retained more DM and N than llamas. Thus the goats appear to be more efficient on these forages than the llamas. Feeding strategy and morphology difference may account for these findings.