Seasonal variation of digestible energy requirements of mature donkeys in the UK

At present there are no published feeding guidelines specific to donkeys. Current recommendations are to feed 0.75 of horse energy needs on a body weight basis. However, it has been shown that donkeys have a greater digestive efficiency than horses and ponies and thus, feeding them as though they were small horses results in excess energy intake and, as a consequence they become obese. The formation of feeding guidelines begins with the estimation of the energy requirement for maintenance, as this is the value upon which nutrient requirements are related to. The aim of the study was to determine the maintenance digestible energy requirements of mature donkeys during each UK season. Twenty mature donkeys (10 male, 10 female) were selected for use in the study. The donkeys were fed a diet of hay and barley straw in quantities that were adjusted to maintain body weight. An equilibration period of minimum 16 days was followed by a five day total faecal collection; this was carried out for each season. Food and faecal samples were analysed for dry matter (DM), organic matter (OM), digestible energy (DE), crude protein (CP), neutral-detergent fibre (NDF) and acid-detergent fibre (ADF); nutrient and energy intakes were calculated. There was a significant seasonal effect on all intakes except NDF and ADF. DM and DE intakes showed significant increases in winter compared to summer, rising by 42 and 35%, respectively. Digestible crude protein (DCP) intakes increased during winter and spring but were significantly lower in autumn compared to all other seasons. A strong seasonal effect was exerted on all in vivo digestibilities although there was no effect of sex. OM, NDF and ADF intakes were affected by sex with male animals having higher intakes compared to female animals. Comparison of these results with NRC (1989) horse requirements showed a considerably reduced requirement by donkeys for energy and protein and thus it was concluded that feeding tables specific to horses are not suitable for calculating donkey requirements.