Research has shown that grinding cereal grains in diets fed to pigs into smaller particle sizes improves growth performance. Feed ground to smaller particle sizes has more surface area on which digestive enzymes can work, so digestibility of energy and nutrients that are enzymatically digested may also be improved. Previous research at the University of Illinois indicated that particle size had no effect on the digestibility of phosphorus, but that decreasing particle size increased energy digestibility in corn in the range of 338.5 μm to 864.5 μm.

However, it is not known if reduced particle size also increases amino acid digestibility. Therefore, an experiment was conducted to determine the standardized ileal digestibility (SID) of amino acids in corn that was ground to different particle sizes and fed to growing pigs.

Animal protein sources such as fish meal and protein plasma are often used in diets fed to weanling pigs because the amino acids in these sources are highly digestible and because animal protein sources do not contain the anti-nutritional factors present in soybean meal. However, the cost of fish meal has increased in recent years and there is, therefore, a need for less expensive alternatives.

Chicken meal and and poultry by-product meal are protein ingredients that have a concentration of amino acids similar to that of fish meal. Poultry by-product meal is produced from the offal of carcasses of slaughtered poultry and includes feet, necks, undeveloped eggs, and intestines. Chicken meal is prepared from clean flesh and skin of chickens without or with bone derived from the whole carcass of poultry. The quality of chicken meal and poultry by-product meal depends on the quality of the rendered parts to produce them. Ultrapro is produced from enzymatically hydrolyzed porcine intestines, and AV-E Digest is produced by enzymatically hydrolyzing whole spent hens and extruded egg albumins. Insufficient data exist on the digestibility of crude protein and amino acids in these ingredients.  Therefore, an experiment was conducted to determine the digestibility of crude protein and amino acids in chicken meal, poultry by-product meal, Ultrapro, and AV-E Digest when fed to weanling pigs and to compare these values with values obtained for soybean meal.

González-Vega, J. C. and H. H. Stein. 2012. Amino acid digestibility in canola, cottonseed, and sunflower products fed to finishing pigs. J. Anim. Sci. 90:4391:4400. Link to full text (.pdf)

Stein, H. H. 2012. Swine NRC revisions explained: Part 2. Pages 12-14 in Feedstuffs, October 29, 2012. Link to full text (.pdf)

Research has shown that grinding cereal grains in diets fed to pigs into smaller particle sizes improves growth performance. Feed ground to smaller particle sizes has more surface area on which digestive enzymes can work, so digestibility of energy and nutrients that are enzymatically digested may also  improved. Generating specific data on energy and nutrient digestibility will help determine the optimal particle size for feed ingredients.

An experiment was conducted to determine the concentration of digestible and metabolizable energy and to measure the apparent (ATTD) and standardized total tract digestibility (STTD) of phosphorus by growing pigs fed diets containing corn that was ground to different particle sizes.

Kim, B. G., D. Y. Kil, Y. Zhang, and H. H. Stein. 2012. Concentrations of analyzed or reactive lysine, but not crude protein, may predict the concentration of digestible lysine in distillers dried grains with solubles fed to pigs. J. Anim. Sci. 90:3798:3808. Link to full text (.pdf)

Protein sources of animal origin provide highly digestible protein in diets for weanling pigs. Chicken meal consists primarily of skin, flesh, and sometimes bones from processed birds. Poultry by-product meal contains offal from processed chickens, including  feet, necks, beaks, undeveloped eggs, and intestinal contents. AV-E digest consists of enzymatically hydrolyzed spent hens and extruded egg albumin, mixed with a soybean meal carrier. Ultrapro is produced from enzymatically hydrolyzed porcine intestines, which are used in the production of the drug heparin. There is a lack of data on the concentration of digestible and metabolizable energy in all of these ingredients, which limits their use in diets fed to weanling pigs.

An experiment was conducted to determine the concentrations of digestible and metabolizable energy in chicken meal, poultry by-product meal, Ultrapro, and AV-E digest, and to compare these values with soybean meal.

Stein, H. H. 2012. The nutritional quality of feed ingredients. Pages 69-77 in Proceedings of the Chinese Swine Industry Symposium, Shanghai, October 24-26, 2012. Link to full text (.pdf)

Distillers dried grains with solubles, or DDGS, is a co-product of the rapidly growing ethanol industry. DDGS has been increasingly used for swine diets because of its affordability and nutritive value. Corn DDGS is high in energy, amino acids, and digestible phosphorus.

In the last few years, more ethanol plants have started  to use centrifugation to extract oil from DDGS for use in the production of biodiesel. The resulting DDGS products contain less fat than conventional DDGS. Reduced-fat DDGS products would be expected to have decreased digestible (DE) and metabolizable (ME) energy concentrations compared with  conventional DDGS, but energy values for these products have not yet been reported.

An experiment was conducted to determine the concentrations of DE and ME in three sources of distillers dried grains with solubles (DDGS) containing different fat concentrations. In addition, the effect of supplementing diets containing reduced-fat DDGS products with corn oil to increase DE and ME concentrations was determined.