1 Department of Animal Science - Animal nutrition and physiology, Department of Animal Science, Science and Technology, Aarhus University2 Department of Animal Science - Animal nutrition and physiology, Department of Animal Science, Science and Technology, Aarhus University
The hypothesis is that cereal proteases in liquid feed degrade and convert water insoluble storage protein into water soluble protein, which may improve the digestibility of protein in pigs compared with dry feeding. Protein utilization is increased by matching the amino acid (AAs) content of the diet as close as possible to the pigs’ requirement. By improving the availability of isoleucine, leucine, histidine and phenylalanine, which are limiting and commercial unavailable, the amount of crude protein in the pig feed can be reduced, resulting in a decreased excretion of nitrogen. The aim was to evaluate the effect of soaking on the amount of water soluble protein and AAs from different winter barley (Hordeum vulgare) cultivars. In this experiment, grains from 9 different barley cultivars were soaked and samples were collected at 15 minutes, 2, 4, 6, 8, 24, 48 and 72 hours. The protein concentration was analysed in the supernatant after centrifugation. After 15 min., app. 16% of the total protein was soluble and until 8 hours an increase of 5% units was observed. However, from 8 to 48 hours it increased with 10% units for some cultivars. Based on these analyses, cultivars were selected for amino acid analysis of water soluble protein at 4, 6 and 48 hours. The amount of glutamic acid after 48 hours indicated that the solubilised protein originated from the prolamin fraction in the grain. Comparison of the amount of isoleucine, leucine, phenylalanine and histidine in relation to the amount of glutamic acid revealed differences between the cultivars and the solubilised protein at all three times. These preliminary results may indicate that improvements of the nitrogen utilization in pigs fed soaked winter barley depends on the choice of cultivar and soaking time, and may serve as a new selection criterion for barley to be used in feeding.