Unvaccinated PigsTake It in the Gut
Telltale signs Lawsonia intracellularis is lurking in a production system: Poor feed efficiency, attrition and lack of uniformity, among others. The bacterium is all too familiar to producers as the cause of that enteric nemesis of growing pigs – ileitis.
From an economic standpoint, many methods to improve feed efficiency are worth pursuing, including oral vaccination. To demonstrate, German Boehringer Ingelheim Animal Health researchers recently published a paper on the impact of ileitis on feed efficiency.
The two authors, G. Behrens and M. Adam, reviewed five international field studies on Enterisol Ileitis, the oral vaccine that prevents ileitis, and its effect on feed conversion ratio (FCR). Thousands of pigs suffering subclinical and clinical ileitis were statistically studied in France (5,800 head), Germany (38,510 head), the Philippines (942 head), Spain (29,060 head) and the United States (120,444 head).
Age of vaccination varied. In France pigs were vaccinated at weaning, for example, and in the Philippines, one group was vaccinated at 22 days and one group at 56 days of age. FCR was measured from the beginning of the finishing phase until slaughter in the German, Spanish and U.S. trials. French and Philippine trials started data collection at weaning.
In all trials, pigs vaccinated with Enterisol Ileitis showed an improvement in FCR from 0.08 to 0.54 lb., regardless of the disease form (see Table 1).
The difference was significant in Germany, Spain and the U.S. The authors noted that improvements in Philippine and French trials confirmed the impact of vaccination, but did not show statistical significance due to the lower numbers of study pigs.
Better FCR also resulted in a healthy economic benefit. Preventing an impact from ileitis through oral vaccination showed a profit of $1.80 at the time, assuming a feed price of $212/ton, with an FCR improvement of 0.10 per pig in the finishing phase (66-253 lb.).
There are several theories as to how or why Lawsonia intracellularis impairs FCR in pigs. Back in 1982, T. Rowan suggested that ileitis is associated with malabsorption of dietary amino acids.1 Pigs with a thickened ileal wall caused by the enteric infection have lower digestion coefficients than normal pigs. It was also suggested the Lawsonia infections trigger profound immune responses that consume nutrients otherwise used for growth.
References:
1. Rowan, T. et al. (1982). Vet Rec. Vol. 110. 306-307.