Grape juice concentrate as a feed for growing pigs

Grape juice concentrate (GJC), which has a dry matter (DM) content of 600-650 g kg^-1, of which 920 g kg^-1 consists of the sugars glucose and fructose, was investigated as a possible feed for growing pigs. The GJC had an overall apparent DM digestibility of 0.980 and a digestible energy (DE) content of 15.0 MJ kg^-1 DM. In five production trials, over 400 Large White × Landrace pigs between 25 and 75 kg live weight were used to investigate the influence of GJC inclusion rate, feeding frequency, and the level and type of protein supplementation on animal performance. The GJC was palatable and no health problems were encountered when GJC contributed up to 0.60 of the DE supply. However, when this reached 0.80, two deaths and reduced appetite and growth rates were observed, although the addition of either water and/or wheat bran to the GJC alleviated the problems. Over all the trials, as the GJC inclusion rate increased the daily liveweight gain (DLWG) decreased, so that a mean value at an inclusion of 0.60 (645 g per day), whilst being perfectly acceptable, was only 0.89 that of animals on control, cereal-based diets. Thus, as GJC inclusion increased from 0-20 to 40-60%, DLWG decreased significantly from 706-700 to 674-625 g per day, SED 25). Frequency of feeding with GJC (1 ×, 2 × or 4 × per day) did not influence pig performance. However, the protein supplement given with the GJC significantly influenced animal performance, with those receiving soya, at either a standard or a higher level, having lower DLWG than all other treatments, whilst when fishmeal was used as the supplement to GJC, performance did not differ from that of the cereal-based control treatment. There were no significant effects of GJC on carcass weights, carcass measurements or meat sample sensory evaluation. Thus, overall, the trials have shown that GJC can successfully be incorporated into the diets of growing pigs at levels of at least 0.40 of dietary DE intake.