Gilts Are More Sensitive to Vomitoxin Than Barrows

The incidence of Fusarium infestation in cereal crops in western Canada has been increasing over the past few years. Fusarium-infected grains produce a toxic metabolite commonly known as vomitoxin. Consuming vomitoxin-contaminated rations can lead to significant reductions in feed intake and reduced pig performance. Generally accepted guidelines suggest that vomitoxin in complete swine rations be maintained at levels under 1 ppm. Faced with a growing supply of contaminated grain, researchers at the University of Manitoba undertook a study to examine the impact of low levels of vomitoxin on feed consumption, weight gain, and carcass parameters of growing-finishing pigs.

The experiment involved 144 pigs (average starting weight of 23 kg) fed a simple barley-based diet containing either 0, 1 or 2 ppm vomitoxin. The different ration concentrations were achieved by diluting contaminated barley with clean, vomitoxin-free barley. The pigs were raised to 110 kg market weight. The results are summarized in Table 1. As expected, vomitoxin depressed feed intake by approximately seven per cent at the 2 ppm level. However, average daily gain and feed conversion were virtually unaffected by treatment.

The most interesting finding from the experiment related to differences between barrows and gilts in the time it took for each to reach market weight. Amazingly enough, the barrows tolerated the vomitoxin-contaminated rations very well and grew at the same rate regardless of treatment. In contrast, the gilts reacted negatively to the vomitoxin treatments. Higher levels of dietary vomitoxin resulted in increased days to 110 kg and there was also a much greater variation in marketing times for gilts receiving the higher vomitoxin levels. Gilts consuming the 2 ppm treatment took as much as two weeks longer to reach market weight compared to the control. The researchers are intrigued by these sex effects of vomitoxin and are in the process of exploring this relationship further.

The researchers also examined carcass quality and found that, as long as pigs were marketed at as close to 110 kg as possible, there was no effect of vomitoxin on carcass weight, index or backfat thickness. They did note, however, that in both barrows and gilts, pigs receiving the diets containing 1 and 2 ppm vomitoxin tended to receive higher loin premiums. Barrows on the 2 ppm vomitoxin diet returned, on average, $0.57 more per pig than barrows receiving 0 ppm vomitoxin diets, with gilts achieving $0.73 more per pig. The researchers hope to do some further experiments to gain some insight into the mechanisms involved in vomitoxin’s effects on carcass quality.

The researchers hope their findings will eventually help to refine feeding programs so that effective strategies can be developed to use vomitoxin contaminated grains for gilts. In the meantime, the results to date suggest that the use of split-sex feeding may allow producers to take advantage of using available vomitoxin-contaminated grains in their feeding programs for barrows. Ongoing research into the impact of vomitoxin on feed intake, performance and carcass characteristics, working alongside initiatives to decontaminate vomitoxin-contaminated grains, will help to ensure that producers can take advantage of local sources of feed grains on-farm.

Table 1. Effect of Vomitoxin-Contaminated Barley on Pig Performance

Vomitoxin Level in Diet

Parameter	0 ppm	1 ppm	2 ppm
Average Daily Feed Intake (kg/day)	2.38	2.29	2.20
Average Daily Gain (kg/day)	0.82	0.83	0.80
Feed Conversion	0.35	0.36	0.36
Days to Market (110 kg)
Barrows	159.2	159.3	158.2
Gilts	167.6	171.6	180.4

By Janice Murphy - Swine Nutritionist/OMAFRA
Ontario Ministry of Agriculture, Food and Rural Affairs
^{Source: Jim House, David Abramson, Gary Crow, and Martin Nyachoti. Can I Use Vomitoxin-Contaminated Barley to Feed my Pigs? Manitoba Swine Update, Volume 14, No. 2, April 2002.}