Feeding phytase-treated corn steep water (CSW) to finishing pigs can be beneficial if the CSW is available at reasonable cost and you don’t feed too much, concludes a new study. However, it can result in reduced weight gain. Dr. Kees de Lange, a Professor in the Department of Animal and Poultry Science, University of Guelph, notes that liquid feeding of swine is increasing in Ontario, allowing the use of inexpensive liquid co-products from the food and bio-fuel industry, such as CSW.
“The producers have to look at the cost benefit of using CSW in their feed,” he says, cautioning that CSW is beneficial only up to 15 per cent of dry matter in liquid diets. “If you go much higher than 15 per cent, it looks like the palatability of the feed is reduced,” he says. Reduced intake naturally results in increased days to market. The study notes that high phytate and sulfur content
may contribute to reduced palatability of CSW. The CSW used in the study, produced at CASCO’s (Canada Starch Operating Company Inc.) London plant, was incubated with phytase to degrade phytate before it was delivered to the Arkell Swine Research Station at the University of Guelph. CSW, a co-product of the corn starch and syrup industry, is available to producers through feed brokers. Four experimental diets were formulated to test the use of CSW (0, 7.5, 15 and 22.5 per cent on a dry matter basis) and
were fed to finishing pigs, starting at a body weight of about 70 kilograms. There were four pens of eight pigs for each treatment, with an equal number of gilts and barrows in each pen. Body weight and per-pen feed usage was monitored weekly. When pigs reached slaughter weight, one barrow and one gilt from each pen were shipped to the meats laboratory at the University of Guelph for detailed assessment of carcass and meat quality. The remaining pigs were sent to a commercial pig processing facility for routine carcass evaluation. The study concludes that phytase may be added to
warm CSW soon after it has been separated from the starch containing fraction in the wet corn milling process. The release of phytate-bound phosphorus was nearly complete 24 hours after phytase was added, and enhances substantially the phosphorus available to pigs. A “negative effective” on growth performance observed when CSW exceeded 15 per cent was due to a slight reduction in feed intake and worsening of feed efficiency. The observed reductions did not affect meat quality except for
a reduction in drip loss from the meat, which means more profit for meat processors.
“We looked at various aspects of meat quality,” de Lange says, “and they were not influenced by the feeding of corn steep water, except for this change in drip loss.”