Gut Health of Broilers in Response to Different Sources and Levels of Copper
Published:June 24, 2024
By:T.T.H. NGUYEN 1, L.M. PINEDA 2, N.K. MORGAN 1, J.R. ROBERTS 1, M. TOGHYANI 1,3 and R.A. SWICK 1 / 1 School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia; tnguy206@une.edu.au; 2 Trouw Nutrition, Amersfoort, The Netherlands; 3 Poultry Research Foundation, The University of Sydney, Camden, NSW 2570, Australia.
Copper (Cu) is a vital element involved in cellular metabolism and enzyme systems. At levels greater than nutritional requirements, dietary Cu addition enhances growth performance as a growth promoter (Pesti and Bakalii, 1996). Copper dosing at levels up to 250 mg/kg feed has been shown to improve intestinal structure and function, and alter the intestinal microbiota profile (Di Giancamillo et al., 2018). However, a high level of copper in the sulphate form (CuSO4) which is chemically reactive, may irritate the gut lining and oxidize fat and other nutrients. Copper in the hydroxychloride form (CH) is comparatively less soluble and reactive than CuSO4 at neutral pH, and presents higher bioavailability.
This study aimed to compare the effects of nutritional and growth-promoting dose of CH with CuSO4, by examining intestinal morphology, caecal microbiota population, and jejunal gene expression. Ross 308 male day-old chicks (n = 864) were fed wheat-soy-based starter (d 0-14) and grower diet (d 14-35). There were eight dietary treatments replicated six times in 48 floor pens: negative control (NC) treatment with no supplemental Cu, 15 and 200 mg/kg Cu from CuSO4 or 15, 50, 100, 150 and 200 mg/kg Cu from CH. On d 14, the pooled caecal contents from three sacrificed birds per replicate were collected for microbial group analysis by real-time quantitative PCR, a 1-cm section of jejunum from each bird was collected for gene expression analysis. Mid jejunum sections were collected for morphology measurement on d 35.
Birds fed diets supplemented with Cu from CH had longer villi compared to those fed CuSO4 supplemented at either level (15 or 200 mg/kg) (P < 0.01), reflecting better absorption of nutrients in the intestine. Increasing dietary Cu linearly decreased the population of both beneficial bacteria - Lactobacillus (P = 0.032), and pathogenic groups - Bacteroides (P = 0.033) and Enterobacteriaceae (P = 0.028). Copper supplementation at 200 mg/kg from CH inhibited the growth of Bacteroides and Enterobacteriaceae compared with the NC diet and 200 mg/kg CuSO4 supplemented diet. CH may have a higher concentration of free Cu-Cu ions at lower parts of the intestine which is soluble and can penetrate into the bacterial cells then change the enzyme activity of the bacteria, leading to bacterial death. Neither copper level nor source had an impact on the mRNA expression of jejunal genes involved in gut integrity (claudin-1, claudin-5, junctional adhesion molecule B, occludin, tight junction protein-1) (P > 0.05). This indicates that that the NC diet was not severely deficient in Cu, and a high level of Cu supplementation, up to 200 mg/kg, does not negatively affect gut permeability in broilers.
In conclusion, supplementation of broiler diets with copper at growth-promoting levels (up to 200 mg/kg) in the CH form alters gut microbiota composition but does not negatively affect gut integrity. Supplementation with copper from CH could be beneficial over CuSO4 at improving intestinal morphology.
ACKNOWLEDGEMENTS: This study was funded by Trouw Nutrition, a Nutreco company.
Presented at the 34th Annual Australian Poultry Science Symposium 2023. For information on the next edition, click here.
References
Di Giancamillo A, Rossi R, Martino PA, Aidos L, Maghin F, Domeneghini C & Corino C (2018) Anim. Sci. 89: 616-624.
Pesti GM & Bakalii RI (1996) Poult. Sci. 75: 1086-1091.
Many products are fighting to enter the animal nutrition market. Many interests are affected by such a simple, elemental and cheap substance. I have personally used it on pigs and poultry. I controlled "Vibrion coli" diarrhea along with bismuth cream or simply finely ground charcoal. The care that must be taken when using it is not to exceed its quantity, particle size and the presence of heavy metals.
Back in the 80´s we used cooper sulfate in broiler and finishing pigs as a growth promoter. Its main effect came from manure that did not showed fungus growth and had a low bacteria count. That effect helped the health of the animals, more that its nutritive an intestinal microbiota populations. From coprophagia (eat feces) had no negative harmul effect.
I agree with you. Sadly EU legislators did not. Certainly there are some soils that can benefit from the addition of high Cu effluent, but many do not and don't sequester enough copper. However, the big concern is/was that run off could be extremely damaging to watercourses. Clearly this is more of an issue in areas with high rainfall and/or a high water table. Unfortunately, legislators are unwilling to nuance legislation and even less willing to rely on farmers to 'do the right thing' . The 'precautionary principle' is king.
Cupric citrate works well in broilers: DOI: 10.1093/ps/77.3.445. About 60 mg CU as citrate replaced over twice as much as sulfate. I don't know about other organic acids. We used citrate because it was the least expensive at the time. The real environmental question should be how much have soil Cu levels been depleted by intensive cropping? Perhaps the extra Cu in the manure would be helpful at times. A quick answer could be found by checking local ruminant feeds for CU supplements. Appropriate answers will also depend on soil types and water tables.
I recall the 'good old days' when we were permitted to use CuSO4 as a 'growth promoter' in pigs. That was before EU legislation prohibited its use because of the potential for adverse environmental effects from the resultant effluent. In my lab, we showed that Cu modulates the antimicrobial effects of organic acids.
Beal, J. D., Niven, S. J., Campbell, A. and Brooks, P. H. 2003. The effect of copper on the death rate of Salmonella typhimurium DT 104:30 in food substrates acidified with organic acids. Letters in Applied Microbiology, 38, 8-12.
We were interested in the interaction between organic acids produced in fermented liquid feed FLF and gut health. FLF also increases the length of the villi. We hypothesised that the interaction between Cu and organic acids could have been a major factor in the growth-promoting effects of Cu. However, by the time that we did that work, we were not permitted to use Cu at growth-promoting levels in pig diets in the EU. Consequently, we did not explore that hypothesis any further.
You might find it interesting to explore the relationship further and determine whether there is an interaction in poultry. If so it might be possible to find a combination of dietary acid and Cu that achieves the desired effects without creating an environmental issue (from high copper levels in faeces).
I have no experience with liquid minerals and copper. I am always cautions about providing things I the water. Water intake is linear functions of days of age and salt level in the feed. On the other hand, feed consumption increases as a curve with age. And then the first obvious sign of a disease in a flock is that water consumption decreases. So it is difficult to provide the right intake and balance without knowing some details for a specific flock.
The responses to copper, including gizzard erosion, will depend on the amount of methionine present. The strong Cu versus Methionine antagonism has been known for a long time. Our old studies showed that if a kg of CuSO4 was added as a growth promoter, to get a really good response the same amount of extra supplemental methionine was needed. https://www.sciencedirect.com/science/article/pii/S0032579119563398?via%3Dihub
In 1991, EPA published a regulation to control lead and copper in drinking water. This regulation is known as the Lead and Copper Rule (also referred to as the LCR). Since 1991 the LCR has undergone various revisions