Protein quality of various raw and rendered by-product meals commonly incorporated into companion animal diets1

Abstract

Several experiments were conducted to evaluate the protein quality of various raw and rendered animal by-product meals commonly used in companion animal diets. Six freeze-dried raw animal meals (beef lungs, pork lungs, sheep lungs, pork livers, oceanfish, chicken necks) and 3 rendered animal meals (lamb meal, regular ash poultry by-product meal, and low ash poultry by-product meal) were fed in chick assays to determine Lys and TSAA bioavailability, protein efficiency ratio (PER), and net protein ratio (NPR). Each experimental diet was offered to 4 replicates of 5 chicks per pen in all growth assays. Furthermore, each animal by-product meal was fed to mature White Leghorn roosters for determination of true AA digestibility. All freeze-dried, raw animal meals were offered to 5 replicate roosters, and all rendered animal meals were offered to 4 replicate roosters. Most raw animal meals exhibited moderate to high protein quality. Lysine bio-availabilities ranged from 86 to 107% and 70 to 99% for raw and rendered animal meals, respectively. Bio-availability of TSAA ranged from 64 to 99% and 61 to 78% for raw and rendered animal meals, respectively. The PER values ranged from 2.83 to 4.03 and 2.01 to 3.34 for raw and rendered animal meals, respectively. The NPR values ranged from 3.83 to 4.8 and 3.05 to 4.12 for raw and rendered animal meals, respectively. Despite a numeric increase in NPR vs. PER values, the overall ranking of animal meals remained similar. Lamb meal had the poorest PER and NPR values, and pork lungs had the greatest values. Total essential AA digestibility and total AA digestibility ranged from 93.6 to 96.7 and 90.3 to 95.5%, respectively, for raw animal meals and 84.0 to 87.7 and 79.2 to 84.8%, respectively, for rendered animal meals. Rendered animal meals generally had lower protein quality than raw animal meals, with lamb meal consistently having the poorest protein quality and pork livers having the greatest protein quality.

A newin vitromethod to evaluate digestibility of commercial diets for dogs

“…The presence of dietary fibre (Burrows et al 1982) and protein digestibility are the factors that most affect the digestibility of a commercial food for dogs, because the digestibility of starch, if it has been properly cooked, and fat is in general very high (Twomey et al 2002;Vhile et al 2007). Protein digestibility of a commercial pet food may be negatively affected by the utilisation of poor protein sources (Cramer et al 2007) and an excessive heat treatment (Opstvedt et al 1984). Undigested protein reaches the animal hindgut, where it may be fermented by proteolytic bacteria, resulting in the production of ammonia and other toxic compounds (including biogenic amines; Russell et al 1983), leading to increased intestinal absorption of ammonia, faecal odour (Macfarlane et al 1986) and higher incidence of intestinal diseases (Ramakrishna et al 1991).…”

The Maillard reaction and pet food processing: effects on nutritive value and pet health

“…These high temperatures and the duration of processing can influence protein quality. Using a chicken growth assay, total lysine availability in raw animal meals ranged from 86·9 to 107·7 % whereas in the rendered animal meals lysine availability ranged from 70·1 to 99·9 % (114) . Differences between total and reactive lysine content in several ingredients of animal origin, mostly rendered meat meals, range from 1·0 % to up to 36·0 % ( Table 1).…”

Prediction of crude protein digestibility of animal by-product meals for dogs by the protein solubility in pepsin method

“…However, they require a specific infrastructure, time and expensive animal care that increase costs. Moreover, there is increasing concern about animal welfare in experimental settings ( 5 ) . In addition, in vivo tests are time consuming, lasting several weeks, and are not suitable for use during ingredient receipt.…”