Feed Management - May/June 2008

fed at typical industry levels compared with the NRC recommended levels. Likewise, sow and piglet body mineral data were evaluated and it was found that while there were effectively no differences between the treatments, with the exception of selenium, the mineral drain on the sows was greater as indicated by the larger litter size and higher sow productivity. The author concluded that feeding inorganic trace minerals in excess of NRC recommendations may be detrimental to sow reproductive performance; however, when these same levels of trace minerals are fed in the organic form, sow reproductive performance is not adversely affected (Peters, 2006) (Figure 2).

Nutrition and the genome

Enhancing reproductive performance in terms of pigs/sow/year is only one measure that should be investigated. Longevity in sow herds is a major focal point as culling rates (mortality and culls) in many situations are approaching 60 percent (Henman,

2006). Genetics can play a major role in longevity as indicated by Close and in a thorough review of the literature heritability estimates were found to be very low and variable (Serenius and Stalder, 2006).

However, Serenius and Stalder (2006) also indicated that although selection for sow longevity may be possible, the application of such technologies would be difficult as selection decisions for sow longevity must be carried out by pedigrees. Enhancing lifetime sow reproductive performance should be an industry goal. Close indicated genetic differences in populations of sows enable certain lines to have an increased herd life of up to one extra parity. Supplementation of sow diets with organic trace minerals under commercial conditions, was found to increase the number of sows remaining in the herd after parity four. In addition, reducing the removal rate in a herd spreads the cost of replacements over more animals. Special attention must be given to reducing the number of animals culled after a single parity as this is extremely expensive.

The future of research in livestock

production will undoubtedly utilize molecular tools to measure and evaluate the impact of new technologies on economically viable production parameters. The term ‘nutrigenomics’ is descriptive of the interaction between nutrition and the genome, thereby combining nutritional research with functional genomics. The information generated from these studies should improve the understanding of nutrition-related diseases and production-relat-ed issues. Dawson (2006) reviewed the impact of nutrients on the genome and how this translates into the formation of functional proteins that drive biological processes, including reproduction. In the not-too-distant future, the utilization of these techniques should allow researchers, and possibly nutritionists, to provide specific nutritional recommendations to combat fertility problems at the commercial level. [FM]