The nutritive value of barley-based diets with forage meal inclusion for growing pigs based on total tract digestibility and nitrogen utilization

Abstract

Digestibility, and retention of energy and nitrogen in growing pigs fed barley-based diets with forage meal (lucerne, white clover, red clover and perennial ryegrass) inclusions (10 and 20%) were studied in change-over experiments. The digestibility of organic matter (OM) was reduced ( P<0.05) by the inclusion of forage meals in the barley-based basal diet, while total fibre (TF), acid detergent fibre (ADF) and crude fibre (CF) digestibilities were increased ( P<0.05). No effect of forage meal inclusion was observed on the digestibility of neutral detergent fibre (NDF). There was a reduction ( P<0.05) in energy digestibility (dE), digestible energy and metabolizable energy (ME) contents of the diets when forage meals were included. The dE was the highest for red clover meal (0.67), and was followed in descending order by white clover meal (0.59), perennial ryegrass meal (0.51) and lucerne meal (0.50). The dE decreased linearly by 0.58, 0.93, 1.02 and 1.15 per percentage unit increase of TF, NDF, ADF and CF in dry matter, respectively. The dietary ME content (MJ/kg DM) decreased by approximately 0.1, 0.2 and 0.3 MJ per percentage unit increase of TF, NDF and CF in dry matter, respectively. Daily N intake and faecal N excretion were increased ( P<0.05) when forage meal replaced barley in the diet. Mainly as a result of the increasing N intake, urinary energy losses were increased ( P<0.05) with forage meal inclusion. The present data suggest that forages have a potential as energy and protein sources in modern pig meat production.