Patrick Garland
Bocm Pauls Ltd, Burston,
Norfolk, IP225TJ,
UK
The design,formulation and manufacture of livestock feeds in the EU, and in particular theUK, have undergone significant changes in the past 25 years. World tradepatterns and economic policies have to some extent shaped these activities butin the more recent past social and political influences have had a moresignificant impact. This paper considers the changes in feed manufacturearising from Salmonella control,withdrawal of animal proteins, removal of used cooking oil, impact of concernsover genetic modification and the move to feeds without antibiotic digestiveenhancers. The requirement for prevention of contamination of ruminant feedswith mammalian products and the specific controls employed are not discussed.
Introduction
It islogical to expect that the economic availability of raw materials suitable foranimal feeds will be evident in the formulation of feeds. Regional policiesmight interfere with the economics of individual raw materials butfundamentally market forces and modern linear programming will determine themake up of rations. For example the CAP (Common Agricultural Policy) determinesthat, via price support mechanisms and import tariffs, the predominantcarbohydrate sources in the UK and most of the EU are wheat and barley ratherthan maize, milo or cassava.
Theseeconomic and political effects tend to be predictable and viable alternativeraw materials or feeding strategies can be developed. This then allows thelivestock industry to maintain a competitive position in the market in which itoperates.
However,when specific demands of powerful purchasers of feed or livestock products aremet the effects might be of little impact, on a world basis, but are highlysignificant locally. The first signs of this occurring arose in the early 80s.
A majorHigh Street retailer in the UK issued a feed specification that was to beapplied to all rations fed to broilers destined for their shelves. In this casethe use of poultry offal meal and South American origin fish meal was excludedon the grounds of Salmonellacontamination risk.
From thispoint onwards the restrictions imposed, usually for sound reasons, increased.The most significant impacts that occur are when a constraint is not universalacross an entire market sector. The exclusion of a material from a feedmiller's facility for one customer could add costs for another purchaser offeed, or having to hold two sources of a similar material has cost implicationsin terms of bin utilisation. Although, the technical solutions to these issueswere usually straight forward, economically and commercially it is oftenproblematic.
In 1988 theUK egg industry was dealt a devastating blow by the revelation that "sadly ahigh proportion of the laying flock is contaminated with Salmonella" (Edwina Currie, Parliamentary Under-Secretary forHealth, 3rd December 1988, television interview). The repercussionswere immediate and dramatic; sales of eggs fell as consumers were faced withtheir first real food scare. This was the first of several issues over thefollowing years which shaped the use of raw materials as well as how animalfeeds are manufactured today in the EU and in particular the UK.
Salmonella control
The levelof Salmonella in UK compound feedshas fallen considerably since 1988; the focus brought to bear on the topicensured that control of the entire supply chain from raw material procurementthrough feed manufacture and delivery was greatly improved. The data in Tables 1 and 2 show the relative degrees of incidence of Salmonella contamination of feed ingredients between 1984-87 and2001-2002. The data are not directly comparable as the earlier information isfrom compounders' own voluntary monitoring, whilst the 2001-2002 data werecompiled by the government. Nevertheless this does show that Salmonella isolations from cereals havebarely changed but those from oilseed products and imported fish meal havefallen.
One of themajor impacts of Salmonella on thefeed industry was that a different approach to raw material procurement had tobe adopted. Monitoring materials by source became an industry standard. Thisallowed compounders to check the biosecurity of high-risk materials and wherenecessary act in a concerted manner through the trade association to bringimproved standards into play at suppliers providing poor quality material.
Themonitoring of six rape crushing facilities between 1991 and 1993 allowed the UKfeed industry, through the offices of UKASTA (United Kingdom AgriculturalSupply Trade Association) to bring pressure to bear on those supplyingconsistently contaminated rape meal. The threat of an industry-wide veto on asupplier is a powerful inducement to improve standards. In terms of processingof feed raw materials to reduce bacterial contamination, little has changed.The occurrence of contamination has been shown to be due to post processingrecontamination and actions taken to prevent this are focused on managementpractices and design of material handling systems. Occasionally it might benecessary to resort to treatment of Salmonella-positivematerial with organic acids or formaldehyde based products. In the case of thelatter concern has been expressed over subsequent amino acid availability but aliterature review and trial studies provided by a supplier of a proprietarypreparation in support of their application for use in the EU shows noreduction in amino acid digestibility (personal communication, Anitox Ltd).
Control of Salmonella in feed mills has had a moredirect impact on nutrition and the cost of feed manufacture. That there was afeed influence on Salmonellaisolations there is no doubt.
In Table 3 the levels of Salmonella found in 1989/90 by onenational compounder compared to comparable figures for 2002/3 show reductionsin the detection of Salmonella. Aswith all industry-based data covering an extended period of time changes in companysize and structure should be borne in mind. In this case the volume of feedmanufactured more than doubled and the numbers of mills and locations changed.Whilst there is no one single element in Salmonellacontrol that can be credited with the better control of Salmonella in feed, heat treatment has often been used as acontrolling point in the feed manufacturing process. Improved hygiene standardsarising from industry codes of practice have also made a significantcontribution to reduced Salmonella.
It is quitefeasible to specify conditions whereby bacteria can be virtually eliminated butthe risk of reducing the nutrient value of the feed is increased. Typicallyfeed for broiler chickens is processed at about 75-85ºC for 15-20 seconds witha moisture content of 15% before pelleting. The frictional forces in the pelletdie can lift the temperature by another 10ºC. There are, though, specificcustomer requirements to process broiler feed at 85ºC minimum for at least 2minutes before pelleting and our own work has shown that this can havedetrimental effects on subsequent bird performance. The data in Table 4 shows liveweight and FCR ofbirds in a cage brooder study to 28 days where different processing conditionswere evaluated at two feed mills.
The need toheat process poultry breeding rations in the late 1980s led to almost universaladoption of crumb or crumble rations. Whilst this met the immediate need for aheat processing step in the manufacture of feeds it gave a physical form thatwas not universally popular due to feed management difficulties at farm level.The potential for heat treated mash products became an attractive means ofrecapturing breeder feed volume from integrated poultry companies where it hadbeen taken in house. In 1997 BOCM PAULS introduced two mash heat-treatmentfacilities, each using different processing systems. As part of thecommissioning process trials were conducted to check the validity of the heattreatment employed. The conditions selected for the processes were lessaggressive than those routinely requested by both retailers and poultrycompanies at the time. The performance data (Table 5) shows a clear advantage in terms of heat treatment foryounger birds and allowed some specification modification for replacementbreeder stock fed heat treated mashes.
A usefulreview of the effect of processing on nutritive value of feeds was given byMcCraken (1999) in which the relative merits and disadvantages of heatprocessing of feed are discussed. From the Salmonellastand point it is clear that aggressive treatments may well give a betterdegree of confidence with respect to bacterial contamination but negativeperformance traits can also arise.
As a resultof heat treatment in the UK the preferred means of enzyme application for bothNSP and phytate substrate is post pelleting liquid application. This in itselfhas capital investment applications.
Protein sources
The rangeof protein sources available for use in poultry rations has reduced over theyears. Concerns expressed by retailers over the suitability of feather mealquickly excluded this material, such that its main use was relegated toruminant protein concentrates for home use and monogastric concentratesexported outside the EU. Similarly questions over the microbiological status ofpoultry offal meals removed these from the ingredient listings of independentcompounders, although some integrators were able to continue using their ownmaterial until the mid 1990s. The focus on intra-species recycling from both adisease prevention and ethical perspective that followed the onset of the BSE(Bovine Spongiform Encephalopathy) outbreak excluded poultry offal from UKformulations, the industry continued to use meat and bone meal of mammalianorigin until March 1996. When the UK government announced a possible linkbetween CJD (Creudzfeldt-Jacob disease) and BSE the industry immediatelystopped using meat and bone meal. There was literally an overnight change indiet formulations and the only protein sources were then fish meal, legumes,pulses, oilseeds and oilseed byproducts.
The mostnoticeable effect was the increase in formulation costs, these varied accordingto ration density but ranged from £8/tonne for high protein starter feeds to £3/tonnefor chicken finisher or layer diets. A heavy reliance upon soy was concerningfrom the point of view of litter quality in broiler chickens and turkeys due toincreased potassium and oligosaccharide levels as well as high crude proteinlevels in feeds. The latter point drove those companies not already formulatingto digestible amino acids to do so. There was an increase in the use ofsynthetic amino acids; threonine became a more attractive ingredient, asformulators sought to balance amino acid profiles in rations and previoussafety margins in diet specifications were reviewed.
Thebenefits of meat and bone meal have been more clearly defined now that we donot have it available. Not only did we lose a source of protein which waslargely of good quality but we no longer had a source of highly availablephosphorous and a significant contributor to the energy level of the feed.
These keyareas are readily covered by most ration specifications and alternative sourcescan be incorporated in formulations albeit at a cost. However, as discussed byBedford and Fothergill (2002) there are other nutrients not routinely specifiedwhich were supplied by meat, bone and offal meals such as glycine, carnitineand conjugated linoleic acid. It is debatable whether these nutrients havebecome limiting but there is valid reasoning in determining exactly what a rawmaterial might be contributing beyond the parameters covered on a formulationdatabase. Conversely there is a risk of attributing too much to a material; greatplay was made of the value of meat meals in providing B vitamins and cholinewith recommendations made to increase supplemental levels. The lesson learntwas that there was already adequate insurance built into vitamin recommendationto accommodate lower background levels.
Strongarguments were put forward to correlate the incidence of pecking andcannibalism in laying hens with the removal of meat and bone meal from feeds.The fundamental flaw in the debate was that the material had been excluded frommost free-range rations on ethical grounds years previously and no change inincidence had been seen. Work published by Hadorn et al. (1999) supports the view that there is no link betweenabsence of animal protein in the diet and increased pecking.
It has beendesirable to use alternative protein sources in poultry feeds and in thisregard rapeseed and rapeseed meals are used at significant levels in meat birdrations. The use of whole rapeseed in particular has been very effective wheremills are able to handle the material as an unprocessed seed. Alternatives towhole rapeseed are expeller meals at approximately 18% oil content or blends ofwhole rapeseed with, typically, peas or beans processed through an expander. Inthe case of the latter, branded products have become well established asbroiler chicken feed ingredients.
Genetic modification
Within theEU there are requirements for non GM (genetically modified) foods and livestockproducts from animals fed on non GM rations. There are a number of categoriesused to define the status of materials used in feeds manufactured to meetspecific market demands.
IP non-GM soya - identity preserved, full traceability of raw material with proof of segregation back to source of seeds planted and exact location of crop grown, <0.1% GM material.Certified non-GM soya. Traceability of material back to factory/silo of origin as a minimum with PCR testing to confirm non GM status as being <1%.North of Santos Soya - port of origin identified with PCR testing to confirm GM status as being <1%. (Lower cost alternative to 1 and 2 above).FAQ. No traceability beyond vessel used to ship to EU. No guarantee of status.
The costsof these different categories vary widely and are influenced by the proximityto either the US or Brazilian harvests for soya bean. At the extreme is IPmaterial which would be used in organic rations and carries a significantpremium.
Unfortunatelydifferent market sectors aim to meet differing aspirations for GM status.Therefore the biggest single issue for feed manufacturers is the availabilityof storage capacity at individual mills servicing a range of customers. It willbe interesting to see how this area develops with the uncertainty in GM policyin Brazil since this is where all of the UK's FEMAS (Feed Materials AssuranceScheme) and North of Santos soya originates from.
So farthere has been little concern over the GM status of vitamins, enzymes and oilblends except in organic feed production.
Fats and oils
As a resultof the BSE announcement in 1996 the use of tallow and poultry fat in fat blendsfor livestock feeds all but ceased. There were initially concerns over thenegative impact on carcass quality due to lower levels of tallow-derivedstearic acid in added fat. This was keenly monitored in turkeys, where for thewhole-bird market, a firm white finish is of importance. For the seasonalmarket where this factor probably outweighs liveweight gain and FCR inimportance (within commercial limits) diets were formulated such that a greaterproportion of energy is derived from cereal carbohydrate.
Whereas fatblends used for poultry feeds could have incorporated 50% tallow along withvarying levels of soya or maize oils (usually acid oils), palm or palm fattyacid distillate and UCO (used cooking oil), there was a rapid move to blendsutilising 50-60% UCO.
This hasproven remarkably successful and no problems have been identified. Since thelevel of free fatty acids (FFA) is high in UCO such that most blends have anFFA content of 40-45% most compounders and integrators have increased Vitamin Esupplementation slightly. However, we had to face another change in legislationwhich has arisen from outbreaks of swine fever in the EU and been influenced bythe finding of dioxin in animal feed fats in Belgium. The use of catering andkitchen waste in animal feeds is no longer permitted in the EU. Thislegislation is primarily targeted at swill feeding of pigs to preventintra-species recycling; due to wording of the legislation it means that usedcooking oil from restaurants cannot be recycled to animal feed. The UK enjoyeda derogation that allowed the collection and use of UCO because of the highdegree of traceability and quality control. But this ended in 2004 and then werely entirely on vegetable oils, acid oils and a small volume of UCO from largefood preparation facilities where the material is clearly traceable to source.The restaurant UCO is already being diverted to biodiesel production.
Antibiotic growth promoters
There hasbeen, and continues to be, pressure on the use of antibiotic digestiveenhancers (ADEs) from both a legislative and consumer perspective. In 1997avoparcin was withdrawn followed by the withdrawal of tylosin, spiromycin,virginiamycin and bacitracin in 1999. This leaves only avilamycin andflavophospholipol as licensed growth promoters for use in poultry feed andthese have been voluntarily withdrawn from a large part of the UK broilerchicken sector. There has not been any significant use (less than 2% of feed) ofantibiotic growth promoters in the laying hen rations since the 1980s and dueto market demands the use in all classes of poultry breeder feeds petered outby the late 1990s.
There is nodoubt that the complete withdrawal of antibiotics from chicken feeds would havea negative effect on physical performance. Even at conservative estimates theseproducts improve weight gain and FCR by 2-3%.
The majorconcern though over the withdrawal of antibiotics, is the likely impact onhealth and subclinical disease. In particular the higher risk of necroticenteritis due to Clostridiaassociated with the withdrawal of the ADEs has changed the way in whichchickens are fed.
There hasbeen a surge in availability of alternative products and trials conducted byBOCM PAULS LTD (see Table 6) havedemonstrated that few if any of these products can match the antibiotics interms of performance in trial facilities. The fact that the price of thesealternatives is higher than the antibiotics does further reduce the cost attractiveness.
The use ofalternatives has been marketing led as much as science led, undoubtedly thereare products which do improve performance compared to a negative control butthe ability to measure this in the field is low. Therefore individual companieshave made their best judgment in choosing a product but often on the basis ofsimply having to add something. This is not a particularly satisfactoryapproach when taken in isolation and the most effective results have beenachieved when companies have considered all of the benefits potentiallyprovided by the antibiotics and taken steps to find alternative means ofachieving them. This has meant reviews of the whole health status of farms,tightening of biosecurity and improving cleanout standards so that all entericdisease is controlled. From a nutritional view point it has become necessary toprovide feeds which give as little opportunity as possible for pathogenicorganisms to get past the birds own immune system.
The following list covers most approaches taken in the UK in the last years.
- Reducebacterial loading of feed, it is perfectly feasible to reduce totalenterobacteriacae to <10 cfu/g by steam pelleting. Field trials with acidshave not been found to provide additional benefits beyond pelleting.
- Improvedigestibility of feeds to prevent supply of nutrients for lower intestinebacterial populations.
- Some re-introduction of maize at greater than 20% has been used effectively.
- Choose high quality sources of raw materials of good digestibility.
- Include oil via oil seeds rather than liquid oils.
- Incorporation of exogenous enzymes, primarily xylanase and phytase. - Maintainfavourable bacterial population.
- Avoid swings in carbohydrate sources i.e. use wheat and barely (also maize ifcosts permit).
- Reduce crude protein content but maintain amino acid profile. - Stimulatephysical activity of intestines.
- Feeding of whole grain wheat
- Coarse grist of feed before pelleting
- Meal feeding rather than ad libitum
- Not grinding wheat before pelleting - Effectivecontrol of coccidiosis and judicious use of ionophore anticoccidials
Considerationof the above along with greater emphasis on farm hygiene does allow theproduction of chicken without major health problems but at a cost that is notreadily identifiable in terms of feed formulation.
References
ACP (2003).Assured Chicken Production. www.assuredchicken.org.uk
Bedford,M.R. and Fothergill, A. (2002). University of Guelph, Animal NutritionAssociation of Canada, Eastern Nutrition Conference. (p.65-789)
Evans, S.and Kidd, S (2003). Salmonella in Livestock, Veterinary Laboratories Agency,Department for Environment, Food, and Rural Affairs, Weybridge, United Kingdom.
Hadorn, R.,Gloor, A. and Wiedmer, H. (1999). Proceedings of the 12th EuropeanSymposium on Poultry Nutrition, Veldhoven, The Netherlands. (p. 349)
McCracken,K.J. (1999). In: Poultry Feedstuffs: Supply, Composition and Nutritive Valueedited by McNab and Boorman Poultry Science Symposium No 26. (p.301-316)
Productionin GB 2002 Report.http://www.defra.gov.uk/corporate/vla/science/science-salm-rep.htm
Wilson, S.(1990). B1-B10 Proceedings of "Control of Salmonella", Society of FeedTechnologists. 25th January 1990, Warwick, UK.
From Proceedings of the "16th Australian Poultry ScienceSymposium", New South Wales, Australia.
