rowth-promoting antibiotics inbroiler diets enhance produc-tion and offer numerous bene-

fits, including increased breast yield, im-proved average daily gains andbetter feed conversion. Yet,even after 50 years of use inanimal production, researchersstill debate the exact mecha-nisms which produce thesepositive results. Now, recentbans on feeding antibiotics atsub-therapeutic levels in theEuropean Union and else-where are forcing feed manu-facturers both inside and out-side the EU to seek other waysto maintain production and an-imal health.

However, no single solutionseems forthcoming. Mixed inwith the extraordinary array of‘all natural’ substances thatseek to replace antibiotics,there is copper (Cu)—in a cou-ple of simple forms for use as afeed additive. Supplementalcopper in poultry diets de-serves renewed attention be-cause it can have positive ef-fects on bird health andimmunity. Copper may be especially use-ful where the use of antibiotics as growthpromoters is curtailed.

Copper is vital in the body as a com-ponent or cofactor in enzyme systems in-volved in iron transport and metabolism,red blood cell formation and immune

function. It is involved in both cell-medi-ated immunity (helping to eliminate in-vading bacteria) and humoral immunity(helping to produce antibodies). These

and other functions make copper evenmore essential where antibiotics are eitherlimited or banned in diets completely.

Reducing stress effects

Stressful conditions like transport,vaccination, diet changes and tempera-

ture fluctuations can lower a bird’s im-munity and cause pathogenic changes inthe gastrointestinal microflora. This mayresult in illness and death, but at a mini-

mum redirects energy and nu-trients away from growth anddevelopment. Many nutrition-ists and veterinarians believeantibiotics prevent stress up-sets by promoting and main-taining a homeostatic environ-ment in the intestinal tract.

Copper can contribute tointestinal health in two ways.As an antimicrobial agent,copper can prevent distur-bances in the balance of mi-croflora. It can also help thegut respond to infections, in-jury and inflammation. Cop-per is involved in protectingcells from free radical damageas a component of superoxidedismutase and copper en-hances iron transport as part ofceruloplasmin.

The required levels of es-sential minerals like coppercan vary depending upon theseverity, duration and type ofstress experienced by an ani-

mal. Broiler nutritionists can more effec-tively maximise productivity and healthby taking these relationships into consid-eration.

Lowering disease challenges

In his in-vitro study conducted at the

Poultry performance and health:

‘Strategic role’ for copperBY JEFF COHEN

Mr. Cohen provides technical salessupport for Micronutrients, an interna-tional supplier of trace mineral products.Contact: Micronutrients, 1550 ResearchWay, Indianapolis, IN 46231, USA, tel+1 404 350 9788, fax +1 404 307 0216,e-mail jeff.cohen@micronutrients.net,website www.micronutrients.net.

G

Table 1. Antimicrobial effect of two copper feed additives.

Bacteria E. coli Salmonella spp. Camplobacter spp.Control >500 colonies >500 colonies >100 coloniesTBCC1 50 colonies<x<100 200 colonies<x<300 50 colonies<x<80Copper sulfate 200 colonies<x<300 400 colonies<x<500 60 colonies<x<80

1Tribasic copper chloride.Source: J. Cohen after J. McNaughton, PARC Institute, 1999.

Note: Copper added to diet from TBCC. The ‘low stress’ birds were grown onwire under equable ambient conditions during springtime; ‘medium stress’ birdsgrew on previously used litter in closed houses; ‘high stress’ birds grew on previouslyused litter and were inoculated on Day 3 with both coccidia and Candida albicans toinduce crop mycosis.

Source: D.M.Hooge, et al., ‘Efficacy of Tribasic Chloride Copper (TBCC) versusCopper Sulfate Pentahydrate in Broiler Chicken Diets’, International Poultry Scien-tific Forum, Atlanta, Georgia, USA, 2000.

Figure 1. Copper level versus body weight in broiler chickens.

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PARC Institute in 1999, Dr. James McNaughton demonstratedthe antimicrobial action of two forms of copper. The microbialscreening procedure involved solutions containing strains of E.coli, salmonella species or campylobacter species sourced fromthe intensive poultry production region in the USA known asDelMarVa (Delaware, Maryland and Virginia). The bacteriawere combined with 250 ppm copper from either copper sul-fate or tribasic copper chloride (TBCC). Treated bacteria sam-ples were incubated for 24 hours on MacConkey and bloodagar plates (table).

By lowering disease challenge, supplemental copper canhelp ensure that a greater portion of a bird’s finite quantity ofavailable energy will be directed towards growth and develop-ment, rather than fending off disease.

Included in almost every trace mineral premix is enoughcopper to satisfy the minimal nutritional requirements of broil-ers and turkeys. It has become a common practice in the USAand elsewhere to supplement these diets with 125 to 250 ppmadditional copper to enhance bird health and well-being. Whilenutritionists debate exactly how copper accomplishes this en-hancement, its use is widespread.

Broilers under stress appear to benefit from increased cop-per, depending upon the stress applied. Trials described by Dr.Danny Hooge at the International Poultry Scientific Forum in2000 indicate that the level of copper needed for optimum per-formance becomes progressively higher with increased stress(Figure 1). Dr. Hooge’s work also showed that extra copperyielded improvement over the controls for all body weights.

Antioxidant effectsOxidation of lipids, fatty acids and fat-soluble vitamins in

feed products can have a negative impact on feed quality and

palatability, ultimately reducing feed intake, performance andoverall health status. Vitamins are particularly susceptible todegradation in premixes and during feed processing and stor-age. Copper can promote bird health and growth by helping topreserve dietary components that are prone to oxidation.

Research at PARC Institute in 1997 showed a significantdifference in the losses of vitamin E during pelleting whenhigher levels of copper were added to broiler feeds. Control di-

ets contained only the basal amount of copper (12 ppm) fromcopper sulfate in the mineral premix while the other treatmentscontained 250 ppm copper from TBCC. In this research, vita-min E activity was measured in serum samples and expressedas a percentage of the level in the unpelleted diet. Vitamin Elosses at 21 days were greater than 26% in the control diets, butless than 10% in the diets containing 250 ppm copper.

Environmental impact

Just as the scrutiny of antibiotics in animal production is in-creasing, so too there is greater attention to trace mineral levelsin manure. Environmental concerns regarding application ofexcessive levels of trace minerals such as phosphorus, zinc andcopper demand attention by nutritionists.

In the case of copper, it is important to use sources that arereadily bioavailable so that lower levels of copper can deliverthe desired benefit (Figure 2). Supplemental copper sources al-so behave differently after deposition in the environment as ma-nure or litter. For example, work with chicken droppings tosimulate agricultural run-off potential suggests that TBCC canreduce leachable copper in the range of 15-32% versus coppersulfate.

Copper can play a strategic role in poultry health andgrowth. It can serve to reduce disease challenges and boost im-mune function. However, there are differences among sourcesof supplemental copper for both the bird and the environment.Feed manufactures should take care to use copper and othermineral sources that will maximise animal health while min-imising the mineral output in waste. fi

Copper contributes to the bird’sintestinal health as an antimicro-bial agent against E. coli, salmo-nella, etc., and in protecting cellsfrom free radical damage.

Figure 2. Relative bioavailabilty (RBV) of common inorganiccopper sources in broiler chickens.

Note: Separate linear regressions of 21-day liver copper levels on supple-mental copper.

Source: D.M.Hooge, et al., ‘Bioavailability of Copper from Tribasic CopperChloride (TBCC) Compared to Copper Sulfate Pentahydrate in Broiler ChickenDiets’, International Poultry Scientific Forum, Atlanta, USA, 2000.

Poultry perfomance and health: ‘Strategic role’ for copper

Reprinted from Feed International, December 2002

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