of calcium and phosphorus that were provided in optimum proportions. The inclusion of fishmeal also brought an additional benefit that was not fully understood, though it was measurable in terms of additional output and an improvement in feed conversion. Research with broilers, turkeys, laying hens, growing pigs and dairy cows regularly showed that diets containing fishmeal enabled them to outperform similar animals that were fed alternative diets that had been matched for energy and protein – and matched for lysine and methionine in the case of non-ruminant trials. Additional benefits from the inclusion of fishmeal were also recorded with early-weaned pigs, which experienced a dramatically reduced incidence of diarrhoea. Consequently, fishmeal was said to contain an ‘unidentified growth factor.’ All of this came to a halt in Europe as a result of the BSE crisis.


Although the European Food Safety Authority considered the risk of infectivity from fishmeal to be remote, the feed became caught up in the risk-reducing measures that were imposed to reduce and eventually eradicate the BSE problem. Although fishmeal was permitted in diets for pigs and poultry, such feeds could not be manufactured in mills where ruminant feeds were also produced because of the risk of cross-contamination. Some years later, when the restrictions on fishmeal were being reconsidered, the ban on its use in ruminant diets was retained because legislators then considered that feeding fish to ‘herbivorous animals such as cattle’ was an unnatural practice – much more so, it would appear, than feeding them on the fruits of the coconut palm! However, since that time, the demand for fishmeal and fish oils


has soared in line with the rapid expansion of aquaculture, whereas the supply has remained relatively constant. Consequently, the point has been reached where fish farms now have to limit the inclusion of fish co- products in their diets. And the price of these invaluable feed materials has risen in line with demand, which has made them uneconomic for most other farming situations, even if their use was permitted. Much of the benefit of the ‘unidentified growth factor’ is now


attributed to the long-chain omega-3 fatty acids, which are contained in fish oil but are absent from other feedstuffs. But, additional benefits of these valuable components are increasingly being recognized in humans and, in consequence, farmed fish have suffered competition from the nutraceutical market. Some fish oils that were previously an important ingredient in aquaculture diets are now being extracted, and people are consuming the omega-3 component, not as part of their diet, but in tablet form. Many farmed fish are now fed rapeseed oil as an energy source and this is a satisfactory replacement, though it does not include the long-chain omega-3 component. Thus the trimmings from the processing of these fish, when converted into fishmeal and fed to farm livestock, will not bring the benefits that the unidentified growth factor used to provide.


Legislative Changes In 2013, the EU authorities relaxed their restrictions and permitted the use of non-ruminant land animal protein in feeds for aquaculture. Given the limited supply and increasing cost of fishmeal, this relaxation was warmly welcomed by the producers and the purchasers of the high protein diets that are commonly used in this industry. However, for the


producers of Atlantic salmon, this development was more than simply a commercial gain because, during the 1990s, these fish had developed a severe problem with cataracts – a permanent opacity of the lens in both eyes – which led to reduced growth rates and secondary disease problems. Research workers linked this problem to a sub-optimal dietary level of histidine, and the richest source of this amino acid was identified as bloodmeal; viz: the histidine content of bloodmeal protein is more than double that found in the protein of white fishmeal or soyabean meal. Thus relaxation of the ban on the use of the co-products of meat processing enabled the aquaculture industry to solve a serious problem by an adjustment to the diet. When land animal feeds were permitted in aquaculture diets, it


was understood that this relaxation would then be extended to pigs and poultry, with the additional proviso that intra-species recycling would not be allowed; i.e. no cannibalism of pig into pig or poultry into poultry. This additional ruling required a demonstration that laboratory procedures could correctly distinguish between pig and poultry fractions when they were included in a compound feed. Suitable laboratory procedures were developed fairly quickly but seven years on from the authorization of land animal feeds for fish, there has been no subsequent agreement on their use for non-ruminant livestock. Since the health risks have now been brought under control,


the consequence of this delay is the annual wastage of more than a million tonnes of protein-rich non-ruminant PAP (the new term that encompasses all the high quality land animal feed sources), and this loss needs to be made up by imports. In recent years, concern about our substantial dependence on imported protein-rich feeds has stimulated research into home-grown alternatives but, to date, they have made only a small impact. Meanwhile the home-grown feeds from meat processing that were satisfactorily used for much of the last century are ready for use now. Such feeds are permitted and used by many countries worldwide, and it is apposite to note that they have a negligible BSE risk. It would seem well to remember that the battle that was fought in Europe during the nineties and noughties was against a disease and not against the animals that suffered from it.


‘Co-product Feeds in Europe’ When ‘Co-product Feeds’ was first published in 2001, the BSE epidemic was still a major concern, and this was quickly followed by a serious outbreak of foot and mouth disease. The use of animal- derived feeds was banned and few people thought to question it. Consequently, this book contained no information on either fish or land animal co-products. Almost twenty years later, the situation has changed and it seems likely that some of the current feed restrictions will be relaxed. Thus, the new book ‘Co-Product Feeds in Europe’ includes detailed information on a number of these nutrient- rich feeds. This new book has 14 chapters and 590 pages, including 100 pages of references.


It is available now from rc@rcfeed.plus.com at £80 inclusive of post and packing.


FEED COMPOUNDER SEPTEMBER/OCTOBER 2020 PAGE 49


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