Survey of the nutrient composition of meat meals and meat co-products with respect to their use as ingredients in aquaculture feeds

Summary

A survey has been carried out to determine the biochemical composition and hence the suitability of Australian meat meals for use in aquaculture diets, particularly in prawn diets. Twenty five renderers from 6 states supplied a total of twenty seven samples of meat meal and one sample of tallow for analysis. 

Meat meal has the potential to be used as a major component in aquaculture diets for fish and prawns to replace or partially replace fishmeal (Williams et al., 1997). The aquaculture feed market could offer an outlet for tens of thousands of tonnes of Australian meat meal if feed manufacturing companies were to adopt recent research findings. However, the feed manufacturers are likely to specify maximum or minimum levels of some of the parameters that have been measured so that the required proportion of meat meal can be included in the diet formulation without compromising other dietary specifications. 

There was great variation in the ash, crude protein and total lipid (fat) between the meat meals. To be used to the fullest extent as an ingredient in aquaculture feeds, a meat meal would have a low ash (< 20%), low fat (< 8%) and high crude protein (> 60%) content. The closer a meat meal approaches the above specifications the more likely it is to be included in a prawn feed formulation and the more of it that can be included in the diet. Though none of the meat meals analysed met these ‘ideal’ specifications, a number did approach them, while others could only be used at relatively low inclusion levels. To illustrate this point, a number of diets have been formulated with varying amounts of either of four hypothetical meat meals in which the ash content varied between 20 and 35% and the total lipid varied between 8 and 14%.

The cholesterol content of the meat meals was generally lower than anticipated and generally lower than found in fishmeal but substantially higher than in plant protein sources. The consequence of this is that where meat meal is used to replace fish meal in a diet formulation, there will be a corresponding reduction in dietary cholesterol that will need to be replaced with a supplementary source. It will be difficult, if not impossible, for some renderers to produce a meat meal that meets the ‘ideal’ specifications for an aquaculture grade meat meal. However, it is important that they recognise the needs of the aquaculture feeds industry and the factors that limit the use of their particular meat meal. Even if a meat meal does not come close to the ‘ideal’ specifications, it can still be used in aquaculture feeds, albeit at lower inclusion levels. The meat meal might  less expensive because of its high ash or fat content, but will be limited in its use in certain diet formulations. A key factor in establishing a supply link to a feed manufacturer is consistency of product. The feed manufacturer is far more likely to use a meat meal if assured that future consignments from that renderer will be of very similar proximate composition and quality.