Abstract

Meat and bone meal is a valuable protein and mineral source in diets of production animals and contributes to the protein, energy and mineral component of diets. The aim of the present study was to more accurately characterise the apparent ileal amino acid digestibility of meat and bone meals produced in New Zealand and evaluate routine in vitro assays used in practise to measure meat and bone meal quality. A total of 94 commercial meat and bone meals from 25 New Zealand rendering plants over a two and a half year period were analysed for proximates, gross energy, gross amino acid content (incl. hydroxyproline, hydroxylysine and lanthionine), apparent ileal amino acid digestibility, pepsin nitrogen digestibility, protein solubility and bone content. The mean crude protein content of the 94 meat and bone meal samples was 56.8% with a range of >35% units and a coefficient of variation of 9.8%. The mean crude fat and ash content were 10.0 and 28.4% respectively. These latter components showed a large range (16 and 43%, respectively) with coefficients of variation above 22%. Amino acid digestibility between samples was highly variable with lysine and sulphur amino acids digestibility ranging between 45.8-89.0 and 38.2-85.5%, respectively. Pearson correlation coefficients are presented between crude protein content and individual gross amino acids, crude protein content and individual digestible amino acid content, and pepsin N digestibility and individual digestible amino acid content. There was a significant relationship between the digestible amino acid nitrogen content and the crude protein content while pepsin nitrogen digestibility was not correlated to ileal amino acid nitrogen digestibility (r=-0.06). Meat meals with a high protein content had relatively low hydroxyproline and hydroxylysine levels something that was attributed to the levels of collagen from bone. The data indicated that lanthionine (formed upon heat treatment of cysteine with a hydroprotein) is not a good indicator of the heat treatment employed to meat and bone meals. Step-wise multiple regression equations to predict the apparent digestible content of amino acids from rapid in vitro assays are presented. The most selected variables included ash and crude fat content. In general the equations derived for the essential amino acids had a higher degrees of fit (R 2 ) compared to the non-essential amino acids. The R 2 for the essential amino acids ranged from 0.43 for histidine and 0.68 for leucine. These equations provide a means of more rapidly estimating the apparent ileal digestible amino acid content (protein quality) of meat and bone meal using standard analyses. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 10 : 1507-1516)

Highlights

  • Meat and bone meal is included in diets for pigs and poultry as a protein source and can contribute up to 30%of the dietary protein supply

  • The data in the present study show that meat and bone meals produced in New Zealand are highly variable in nutritional quality

  • The ash content in meat and bone meal does not contribute to the energy component of meals

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Summary

Introduction

Meat and bone meal is included in diets for pigs and poultry as a protein source and can contribute up to 30%of the dietary protein supply. Meat and bone meal is included in diets for pigs and poultry as a protein source and can contribute up to 30%. Besides being a valuable protein source, meat and bone meal contributes to the energy component of the diet and is a good source of calcium, phosphorus and trace minerals. The nature of the raw materials as well as the processing methods used to produce meat and bone meal, can result in a highly variable product in terms of chemical composition and protein quality. Ashley (1983) reported wide variability in the crude protein, fat and ash contents of meat and bone meals produced in the United Kingdom and Europe. Crude protein levels ranged from 31 to 66% (as is) while ash levels ranged from 12 to 40% (as is) in meat and bone meals produced in the United Kingdom.

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