Development of an ad libitum feeding regime for group-housed dry sows
One of the main deterrents against group-housing systems of dry sows is the aggression between animals and the expensive designs necessary to prevent this. This is related to the low feeding level accepted in practice. The low level of feeding is also linked to the occurrence of stereotypies which are generally accepted as an indication of poor welfare. An ad libitum feeding system which does not result in excessive intake and concomitant problems of obesity, might improve sow welfare and have economical advantages in reducing capital cost. Suitable diets might be high-fibre diets. High inclusion levels of several fibrous materials failed to prevent excessive intake. Only unmolassed sugarbeet pulp gave acceptable results, when included at a level of 580 to 650 g/kg. Composition of the fibre appeared to be more important in regulating voluntary intake than fibre concentration of the diet per se. A diet containing a high level of sugarbeet pulp (SBP) had a long transit time and high nutrient digestibility. Nutrient digestibility was influenced by protein level and source. A SBP diet appeared to regulate intake by physical, physiological and metabolic mechanisms. The large volume of wet sugarbeet pulp will increase gastro-intestinal fill. The rate of glucose absorption and secretion of insulin was reduced. A high pre-feeding plasma VFA concentration indicated a more constant supply of nutrients for a longer period after feeding. A SBP diet increased feeding time four-fold. Animals receiving a SBP diet were less active and engaged to a lesser extent in post-feeding oral behaviours. A marked reduction in time spent rooting suggests that the sows were less food-motivated.