"Recommendations for the inclusion rate from conventional canola meal range from 10 to 15 to 20 per cent," said Hans H. Stein, U of I professor of animal sciences.

"And now we have this new product, high-protein canola meal, for which there is very limited information. So we wanted to test different inclusion rates of these products to determine how they affected growth performance."

To do so, Stein's team fed weanling pigs diets containing two different varieties of high-protein canola meal (designated CMA and CMB), as well as a diet containing conventional canola meal (designated CM-CV). CMA and CM-CV were included at 10, 20, 30, or 40 per cent of the diet, while CMB was included at 10, 20, or 30 per cent.

They then measured growth performance, organ weights, bone ash, and blood characteristics from pigs fed each diet, and compared them with pigs fed diets containing no canola meal.

Liver weights were greater in pigs fed greater amounts of CMB, kidney weights decreased as inclusion of CM-CV increased, and thyroid gland weights increased as inclusion of CMA increased.

Increasing inclusion of canola meal, regardless of variety, increased bone ash percentage relative to pigs fed diets containing no canola meal. Thyroid hormone production was decreased as inclusion rates of CMA and CM-CV increased. No difference in heart or bone weights, complete blood count, or blood urea nitrogen was observed among pigs fed the different diets.

The researchers determined that adding canola meal to the diets did not affect average daily gain.

Average daily feed intake was decreased with increased inclusion of canola meal, regardless of variety. The gain to feed ratio increased with increasing inclusion of CMA or CM-CV in the diets, but inclusion of CMB in the diets had no impact on gain to feed.

"While some differences in organ weights and thyroid hormone secretion were observed in pigs fed different amounts of high protein or conventional canola meal, these differences did not affect growth performance," Stein said.

"These results indicate that either conventional or high-protein canola meal can be used in diets for weanling pigs at an inclusion rate of at least 20 per cent, and possibly as much as 40 per cent."

The paper, Effects of high-protein or conventional canola meal on growth performance, organ weights, bone ash, and blood characteristics of weanling pigs, was co-authored with Chelsie Parr, Yanhong Liu, and Carl Parsons of the University of Illinois.

It was published in a recent issue of the Journal of Animal Science.