Digestion, faecal grain loss and energy requirements of Huacaya alpacas fed lucerne chaff, oat chaff and whole grain barley diets

Abstract This study determined the digestibility of three common supplementary feeds, faecal whole grain loss and the energy requirements of adult Huacaya alpacas (live weight 62 kg) using individual pens and feeding at a range of initial notional energy levels approximating maintenance (M) to 1.6 × M. The diets were lucerne (Medicago sativa) chaff (LC), oaten (Avena sativa) chaff (OC) and whole barley grain (Hordeum vulgare) plus oaten chaff (BOC) (40:60 ratio). After 2 weeks introduction, DMI, faecal output and live weight were measured for 7 days. Samples were analysed for DM, organic matter (OM), GE and N content. Feed composition was respectively for diets LC, BOC, OC: OM 89.1, 96.4, 95.8 %; DE 12.8, 11.9, 12.2 MJ/kg DM; CP 21.7, 9.6, 7.3 %. OC included 25 % oat grain, of which 55 % was whole grain. Two alpaca showed signs of subclinical acidosis. DMI averaged 1014 g/d (range 579−1576 g/d) during digestibility measurements. Whole grain loss as % of grain fed was 16.3 % for BOC significantly greater than 5.2 % for OC. For LC and BOC, DMI required for alpacas at maintenance was 41 g/kg W0.75/d, equivalent to 1.48 % of live weight, and the MEm requirement was 399 kJ ME/kg W0.75/d. Energy retained in fibre averaged 180 (s.e. 6.6) kJ/day and was 0.0146 of ME intake, equivalent to 8.2 ± 0.30 kJ/kg0.75/d. While it was possible to feed up to 435 g DM/d of cereal grain to alpaca, whole barley grain excretion was associated with a 27 % decline in the ME value of barley. Alpaca fed whole grain barley adapted to the diet whereas adaptation to a diet of oaten chaff with cracked oat grain resulted in depressed DMI and live weight loss, probably from mild acidosis.