Feed Additives in Swine Diets: An Update

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Many swine producers use feed additives because of their demonstrated ability to increase growth rate, improve feed utilization, and reduce mortality and morbidity from clinical and subclinical infections (Dritz et al., 1997). Much research has been performed to try to determine what additives should or should not be used in swine diets, especially for the newly weaned pig. Copper and zinc are by far the most heavily researched growth-promoting minerals. Weanling pigs have a dietary requirement of 5 to 7 ppm. Studies have shown that elevated dietary copper or zinc supplementation (100 to 250 ppm) will generally result in growth promoting effects in weanling pigs, but the use of both does not seem to double the benefits (Hill et al., 2000). Hill et al. (2001) also found that the addition of the antibacterial agent carbadox (0 or 55 mg/kg) to a zinc supplemented (1,500 to 2,000 mg Zn/kg, in the form of ZnO) diet result in additive performance improvements.

Unfortunately, the excess minerals end up in the lagoons, adding to the ongoing battle between pork producers and environmentalists. Here at Virginia Tech an experiment is being performed to assess the efficacy of an organic compound, Bioplex (Alltech Inc.), as a growth promoter for weanling pigs at 100 ppm and 200 ppm doses, relative to similar levels of copper from copper sulfate. If lower levels of the organic compound give the same response as higher levels of copper sulfate, then less copper ends up in the lagoon.

As alternatives to traditional additives like antibiotics, herbs and herbal mixtures are also receiving increasing attention. Many herbs and spices are known to have compounds with anti-bacterial effects. Herbs may also increase the palatability of diets and thereby increase feed intake. Most of the work to date has been done in Europe, but there is increasing interest among scientists in the U. S. (Doyle, 2001). Scientific studies will be critical to ascertain the validity of claims for such compounds, many of which will be advertised on the Internet (Growell, 2001).

One such study was reported at the animal science meetings this past July. Corrigan et al. (2001) examined the different effects of three dietary growth-promoting additives on the performance of nursery pigs. They studied the effects of zinc oxide (3000 ppm added zinc), an antibiotic (CSP 250®), and an herbal blend (ApexTM 3050). The results of the experiment suggest that all three were effective in increasing ADG, ADFI, G:F, and reducing morbidity.

It is clear that there are many alternatives to improving the performance of pigs, but at this time it is not yet apparent what works best for all systems of production.

Corrigan, B. P., B. F. Wolter, M. Ellis, and S. Moreland. 2001. Effect of three dietary growth promoting additives on performance of nursery pigs. J. Anim. Sci. 79 (Suppl. 1):1885 (Abstr.).

Doyle, M. E. 2001. Alternatives to Antibiotic Use for Growth Promotion in Animal Husbandry. FRI Briefings. Food Research Inst., Univ. Wisc-Madison.

Dritz, S. S., R. D. Goodband, M. D. Tokach, and J. L. Nelssen. 1997. Feed Additive Guidelines for Swine. Swine Nutrition Guide. Kansas State University, Manhattan.

Growell. 2001. Growell, India home page. Available at: http://www.growell.com. Accessed Nov. 15, 2001.

Hill, G. M., G. L. Cromwell, T. D. Crenshaw, C. R. Dove, R. C. Ewan, D. A. Knabe, A. J. Lewis, G. W. Libal, D. C. Mahan, G. C. Shurson, L. L. Southern, and T. L. Veum. 2000. Growth promotion effects and plasma changes from feeding high dietary concentrations of zinc and copper to weanling pigs (regional study). J. Anim. Sci. 78:1010-1016.

Hill, G. M., D. C. Mahan, S. D. Carter, G. L. Cromwell, R. C. Ewan, R. L. Harrold, A. J. Lewis, P. S. Miller, G. C. Shurson, and T. L. Veum. 2001. Effect of pharmacological concentrations of zinc oxide with or without the inclusion of an antibacterial agent on nursery pig performance. J. Anim. Sci. 79:934-94.