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.

Twelve weanling barrows with an average initial body weight of 12.2kg were fed one of six diets. One diet contained soybean meal as the sole source of amino acids. The four experimental diets contained soybean meal in addition to chicken meal, poultry by-product meal, Ultrapro, or AV-E Digest. A nitrogen-free diet was used to estimate basal endogenous losses of crude protein and amino acids. Ileal digesta were collected and analyzed for dry matter, crude protein, and amino acid content.

Soybean meal had the greatest standardized ileal digestibility of crude protein and nearly all amino acids of the ingredients studied. The exceptions were proline, for which no difference in digestibility was found among the five ingredients tested, and tryptophan, for which the digestibility in soybean meal did not differ from that in AV-E Digest. The digestibility of crude protein did not differ between poultry by-product meal and AV-E Digest, while crude protein digestibility was less in chicken meal than in AV-E Digest, but did not differ from the digestibility in poultry by-product meal.  Ultrapro had the least digestibility of crude protein.

Soybean meal had the greatest mean digestibility value for indispensable amino acids, with AV-E Digest having the second greatest value. The mean digestibility of indispensable amino acids was less in chicken meal and poultry by-product meal than in AV-E Digest, and did not differ between those two ingredients. Ultrapro had the least mean digestibility of indispensable amino acids, but  this value did not differ statistically from chicken meal. This pattern was also present for most individual indispensable amino acids.

The mean digestibility of all amino acids was greatest in soybean meal, followed by poultry by-product meal and AV-E Digest, which did not differ from each other. The mean digestibility of all amino acids was less in chicken meal than in AV-E Digest, and the same as in poultry by-product meal. However, the mean digestibility of all amino acids was less in Ultrapro than in poultry by-product meal, and the same as in chicken meal.

• Amino acids from chicken meal, poultry by-product meal, Ultrapro, and AV-E Digest are well digested by pigs, which indicate that these products may be suitable sources of digestible amino acids in diets fed to weanling pigs.
• Of the alternative animal proteins tested, the digestibility of crude protein and amino acids was greatest in AV-E Digest.
• Performance experiments need to be conducted to confirm that chicken meal, poultry by-product meal, Ultrapro, and AV-E Digest may replace fish meal in diets fed to weanling pigs.

Table 1. Standardized ileal digestibility (SID) of CP and AA in chicken meal (CM), poultry by-product meal (PBM), Ultrapro, AV-E Digest, and soybean meal (SBM) by weanling pigs

^a-dMeans within a row lacking a common superscript letter differ (P = 0.05).

This research report is based on research presented at the Midwest Swine Nutrition Conference in Indianapolis, Indiana on September 13, 2012. The conference paper is available at http://nutrition.ansci.illinois.edu/node/697.