Effects of Environment, Genotype, and Health Management System on Pig Growth Performance and Carcass Characteristics
Purdue University 1998 Swine Research Report. A number of research trials and producer observations suggest that the lean growth rates of high lean growth genotypes are substantially reduced under commercial conditions. Pigs reared under commercial conditions have lower feed intakes and reduced growth rates in comparison to pigs reared under ideal conditions. It has also been observed that when low-medium lean growth genotypes are raised under ideal conditions, lean growth rate is only marginally increased from 100 to 260 pounds. Low-medium lean growth genotypes respond to more ideal conditions by consuming feed in excess of that needed for maximum lean growth, and subsequently become fatter. Barrows of a number of low to average lean growth genotypes have .1 to .3 inch greater backfat depths when fed under more ideal conditions. A number of antibiotics have growth promoting effects through the lowering of disease levels and increased nutrient utilization. Tilmicosin (Pulmotil), a product from Elanco Animal Health, is a medication designed for use in pigs at risk for bacterial pneumonia. Various research trials have shown pigs receiving tilmicosin have an increased average daily gain and feed efficiency in addition to a reduction in or elimination of death loss. This product requires a Veterinary Feed Directive from a veterinarian before it can be bought and used by producers. The increased growth rates may be associated with increased production of growth promoting factors such as insulin-like growth factor (IGF-1) and the reduction of inhibitory factors via an ability to reduce disease levels. Little research has been conducted on the response of growth promotants in high health status pigs and the underlying biology of the mode of action. It would be expected that high health status pigs would show less of a response to therapeutic medications than pigs of average health status for respiratory diseases.