THE NUTRITIVE-VALUE OF BARLEY-BASED DIETS WITH FORAGE MEAL INCLUSION FOR GROWING PIGS BASED ON TOTAL TRACT DIGESTIBILITY AND NITROGEN-UTILIZATION

Digestibility, and retention of energy and nitrogen in growing pigs fe d barley-based diets with forage meal (lucerne, white clover, red clov er and perennial ryegrass) inclusions (10 and 20%) were studied in cha nge-over experiments. The digestibility of organic matter (OM) was red uced (P < 0.05) by the inclusion of forage meals in the barley-based b asal diet, while total fibre (TF), acid detergent fibre (ADF) and crud e fibre (CF) digestibilities were increased (P < 0.05). No effect of f orage meal inclusion was observed on the digestibility of neutral dete rgent fibre (NDF). There was a reduction (P < 0.05) in energy digestib ility (dE), digestible energy and metabolizable energy (ME) contents o f the diets when forage meals were included. The dE was the highest fo r red clover meal (0.67), and was followed in descending order by whit e 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 perc entage unit increase of TF, NDF, ADF and CF in dry matter, respectivel y. 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 ma tter, respectively. Daily N intake and faecal N excretion were increas ed (P < 0.05) when forage meal replaced barley in the diet. Mainly as a result of the increasing N intake, urinary energy losses were increa sed (P < 0.05) with forage meal inclusion. The present data suggest th at forages have a potential as energy and protein sources in modern pi g meat production. (C) 1998 Elsevier Science B.V.