Energy metabolism and methane production in llamas, sheep and goats fed high- and low-quality grass-based diets

This study aimed to test whether the digestive and metabolic characteristics of pseudo ruminants provide superior ability to utilise low-quality diets compared to true ruminants. A total of 18 mature, non-pregnant, non-lactating female animals, including six llamas (Lama glama), six Danish Landrace goats and six Shropshire sheep, were used in a crossover design study. The experiment lasted for two periods of three weeks. Half of the animals were fed either high-quality grass hay (HP) or low-quality grass seed straw (LP) during each period. Animals were placed in metabolic cages during the last 5 d, and gaseous exchange was measured by open-circuit indirect calorimetry for 22 h. Metabolisable energy for maintenance (MEm) and fasting energy expenditure (FEExp) were estimated by regression approach. Dry matter (DM) intake per kg(0.75) was substantially reduced in llamas and sheep, but not in goats, on the LP compared to HP diet. Llamas had lower daily energy expenditure (324 kJ.kg(-0.75)) than sheep (416 kJ.kg(-0.75)) and goats (404 kJ.kg-(0.75)) on the LP diet. Llamas in comparison with sheep and goats had lower methane emission (0.83 vs 1.34 and 1.24 l.d(-1).kg(-0.75), p < 0.05), lower MEm (328 vs 438 and 394 kJ.d(-1).kg(-0.75), p < 0.05) and lower FEExp (246 vs 333 and 414 kJ.d(-1).kg(-0.75), p < 0.05), respectively. In conclusion, llamas had lower basal metabolic rate and hence maintenance requirements for energy.