Study Provides Nutritional Value for Food By-products for Use in Pig Feed06 February 2014
The energy content of maize by-products for pigs was found in two studies at the University of Illinois to be inversely related to their fibre content. While phosphorus digestibility varied in the feed ingredients tested, it was not increased by the addition of phytase in all cases.
Co-products from the human food industry offer a lower-cost alternative to cereal grains in diets fed to pigs. Research at the University of Illinois is helping to determine the nutritional value of these ingredients so that producers can make informed choices about incorporating them into swine diets, said Hans H. Stein, an animal science researcher at the University.
Researchers led by Professor Stein conducted two experiments using corn and corn co-products. In the first experiment, they measured the concentrations of digestible and metabolisable energy in distillers dried grains with solubles (DDGS), hominy feed, bakery meal, corn gluten meal, corn gluten feed and corn germ meal.
In the second experiment, they determined the standardised total tract digestibility of phosphorus in pigs fed diets containing these ingredients without or with the addition of microbial phytase.
Corn gluten meal contained 5,379 kilocalories of digestible energy per kilogram of dry matter, more than in any of the other ingredients. The digestible energy (DE) concentrations in DDGS (4,062kcal per kg), corn (4,032kcal per kg), bakery meal (3,951kcal per kg) and hominy feed (3,819kcal per kg) were similar but corn gluten feed (3,553kcal per kg) and corn germ meal (3,437kcal per kg) contained less digestible energy than all the other ingredients.
Corn gluten meal also had the greatest concentration of metabolisable energy (ME) at 4,400kcal per kg dry matter, followed by corn (3,891kcal per kg), DDGS (3,694kcal per kg), hominy feed (3,675kcal per kg) and bakery meal (3,655kcal per kg). Corn gluten feed (3,169kcal per kg) and corn germ meal (3,150kcal per kg) contained the least metabolisable energy.
"Addition of phytase to the DDGS, corn gluten meal and corn gluten feed diets did not affect phosphorus digestibility."
"The main reason DE and ME concentrations are greater in corn gluten meal than in corn is that corn gluten meal contains more crude protein and less fibre," Professor Stein explained. "Hominy feed, DDGS, corn gluten feed and corn germ meal contain much more fibre than corn, which contributes to their lower energy digestibility."
The standardised total tract digestibility of phosphorus was 75 per cent or greater in DDGS, corn gluten meal and corn gluten feed. The digestibility of phosphorus in bakery meal and corn germ meal was greater than 50 per cent and in corn and hominy feed, it was less than 50 per cent.
Addition of microbial phytase to the diet increased the digestibility of phosphorus in corn, bakery meal, corn germ meal, corn germ and hominy feed but addition of phytase to the DDGS, corn gluten meal and corn gluten feed diets did not affect phosphorus digestibility.
"Different corn co-products contain different quantities of phytate-bound phosphorus due to differences in composition and processing," Professor Stein continued. "By adding microbial phytase to the diets, we were able to increase the digestibility of phosphorus to greater than 60 per cent for all ingredients."
'Phosphorus digestibility and concentration of digestible and metabolisable energy in corn, corn co-products and bakery meal fed to growing pigs' was recently published in the Journal of Animal Science. It was co-authored with Oscar Rojas and Yanhong Liu of the Stein Monogastric Nutrition Laboratory at the University of Illinois.
The full paper is available online.
The National Pork Board and Nutrition Efficiency Consortium provided funding for the studies.