Source of the Variation in Meat and Bone Meal Nutritional Quality

W H Hendriks,D V Thomas,P C H Morel,Y H Cottam

doi:10.5713/ajas.2004.94

Abstract

The gross composition, gross amino acid content, apparent ileal amino acid digestibility and apparent ileal digestible amino acid content from 64 commercially produced meat and bone meals were statistically analysed. The samples were produced by 22 plants over a 2.5 year period with eight plants using batch dry rendering and 14 plants using low temperature rendering. A linear model with method and time of year (period) as fixed effects, plant within method as a random effect and sheep percent as a covariate was fitted to the composition data. The majority of the variation in the gross composition, amino acid digestibility and digestible amino acid content was explained by differences between plants using the same method. Neither rendering season nor origin of the raw materials contributed significantly to the observed variation in meat and bone meal protein quality. Rendering method (low temperature or batch rendering) had a significant effect on the variation observed in gross fat content, gross energy content, pepsin nitrogen digestibility, protein solubility and total lanthionine content. The digestibility of a number of amino acids and the apparent digestible content of arginine, cysteine, aspartic acid, proline and hydroxyproline were also significantly affected by rendering method. On average, batch dry and low temperature rendering systems produce meat and bone meals of similar nutritional quality. The variation between plant and within plant, however, is large, indicating that purchasing meat and bone meal from the same plant does not guarantee a consistent quality.

Highlights

The effect of rendering method on the protein quality of meat and bone meal is confounded by the effects of the pressure and temperature used by the various methods
In a recent study (Hendriks et al, 2002), we reported a large variability in the protein quality of meat and bone meals produced in New Zealand, believed to originate from the factors affecting the production of meat and bone meal as discussed above
Meat and bone meal is a co-product of the meat industry and its composition and protein quality are affected by the raw materials used, the rendering processes used and the processing conditions employed during rendering

Summary

INTRODUCTION

The aim of the present study was to quantify the contribution of a number of factors including raw material origin, season and rendering system to the total variability in protein quality of commercially produced meat and bone meal. Meat and bone meal is a co-product of the meat industry and its composition and protein quality are affected by the raw materials used, the rendering processes used (batch dry, continuous dry or low temperature rendering) and the processing conditions employed during rendering. Johnson and Parsons (1997) investigated the effect of raw material source on the protein efficiency ratio (PER) and net protein ratio (NPR) of growing chickens and reported that raw material source influenced both PER and NPR values for animal meals The latter authors found that ash content and processing temperature affect the PER and NPR of meat and bone meals. These included dry significant at a probability level of 5%

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DISCUSSION

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