In Situ Digestion of Forages and Grains in Alpacas fed Alfalfa and Grass Hay

Abstract

In situ disappearance of alfalfa hay, grass hay, corn, corn/oats/barley and oat DM and NDF in alpacas fed alfalfa hay (AHF) or grass hay (GHF) was determined in adult male alpacas. The alpacas were then divided into two groups. Alpacas were fed alfalfa hay or grass hay for thirty days prior to the treatments and given water ad libitum throughout. In situ substrates tested included alfalfa hay (AHS), grass hay (GHS), corn (CS), corn/oats/barley/molasses (COBS) and oats (OS). Each forage sample was incubated in each alpaca for 4, 8, 12, 24, 36 and 72 hours and the grain substrates incubated for 2, 4, 6, 12, 24, 36 and 72 hours. Substrate treatments were administered in random order to each alpaca for the two forages fed. Forage residue was analyzed for DM and NDF, and grain residue for DM concentrations. The DM and NDF totals were divided into three categories: a = immediately soluble; b = the non-soluble but degradable; and u = non-degradable/unavailable, potential extent of degradation (PE), degradation rate (c) and effective degradation at 2 %∙hr-1 (ED2) and 4 %∙hr-1 (ED4). All DM parameters were significant for feed substrates (P<0.001). DM c was also significant for forage and the interaction (P<0.001). NDF parameters were only significant for fraction b and PE (P<0.001). Degradation in these alpacas was not different between the two forages provided and although distinct from true ruminants in digestive physiology showed similar digestion parameters for the feed tested.