Effects of feeding sorghum-sudan, alfalfa hay and fresh alfalfa with concentrate on intake, first compartment stomach characteristics, digestibility, nitrogen balance and energy metabolism in alpacas (Lama pacos) at low altitude

摘要

The objective was to evaluate effects of feeding sorghum-sudan- or alfalfa-based diets on intake, first compartment stomach characteristics, digestibility, nitrogen balance and energy metabolism in alpacas at low altitude (793 m). Six mature alpacas (42pl2.3 kg of body weight) were used in a replicated 3c3 Latin square experiment. The treatments were: sorghum-sudan diets (SSD), alfalfa hay diets (AHD) and fresh alfalfa diets (FAD), respectively. Alpacas were housed in metabolism crates and diets were fed for 21 days with 11 d of adaptation and 10 d of sampling. Alpaca was supplemented concentrate with 160 g per alpaca per day and forages were fed at 12 h intervals with water provided ad libitum. First compartment stomach pH and ammonia N were unaffected by forage source, whereas total VFA concentration was different between diets, with the least for FAD (46.8 mM), followed by AHD (51.8 mM) and the highest for SSD (56.1 mM). Ratio of acetate to propionate was greater for AHD and SSD than for FAD diets. The molar proportion of acetate decreased, whereas the molar proportion of propionate increased for FAD relative to AHD and SSD. Redox potential was lower for SSD than for FAD. Surface tension was greater for FAD than for SSD and AHD. Osmolality was lower for FAD than for SSD and AHD. First compartment pressure and methane production tended to be higher for FAD than for SSD (P <0.06) and AHD (P <0.07). Digestibilities of DM, OM and EE were not different between diets. However, the digestibility of CP was lower for AHD relative to SSD and FAD. Digestibilities of NDF and ADF were greater for SSD than for AHD and FAD. Intakes of gross energy (GE) and N were greater for AHD than for FAD and SSD. Digestible energy (DE) was the highest in AHD followed by SSD and FAD. Metablizable energy (ME) was different with the lowest for FAD (3.9 MJ/day), followed by SSD (5.4 MJ/day) and the highest for AHD (8.1 MJ/day). Energy retained was followed the same trend as ME. The results demonstrate variable responses of alpacas to feeding sorghum-sudan or alfalfa diets in terms of dry matter intake, first compartment stomach characteristics, digestibility, nitrogen balance and energy metabolism at low altitude.