Liquid feeding of pigs : potential for reducing environmental impact and for improving productivity and food safety.

Summary Liquid feeding creates an opportunity to recycle liquid residues from the human food industry as animal feed. Such residues are often low in dry matter and variable in composition. However, if diets are reformulated frequently to take account of such changes there is no loss of productivity and profitability can be increased. Modern liquid feeding equipment facilitates frequent changes in diet composition, delivery of different diets to different pens of pigs and enables pigs to be fed ad libitum or accurately rationed. These features provide an opportunity to use ‘step’ and ‘phase’ feeding regimes that can reduce the nutrient content of effluent and reduce environmental loading. Current research is investigating ways of increasing the efficiency of utilization specific raw materials by the targeted use of exogenous enzymes. Surveillance studies have shown that liquid feeding reduces Salmonella incidence. This has been particularly associated with the use of acidic residues derived from the food industry. More recently, and particularly because producers wish to feed liquid diets ad libitum, there has been much interest in the concept of feeding fermented liquid feed (FLF) to pigs. Natural, uncontrolled fermentation has produced very mixed results on commercial units. However, when selected lactic acid bacteria inoculants are used and fermentation conditions are carefully controlled, an acidic diet is produced that rapidly and effectively excludes enteropathogens. Such feed is readily accepted by pigs and it has been shown to enhance post–weaning growth and reduce coliform levels in the lower gut. Because of this FLF may be a useful alternative to antibiotic growth promoters. Although results in experimental units are impressive, more research is needed before we can provide Standard Operating Procedures relevant to different conditions. These are needed to enable the transfer of this exciting technologyto commercial pig units.

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