“The trial used a new hybrid rye that is now grown in Canada and has a much higher yield than conventional rye,” explains Miranda Smit, livestock research extension coordinator with Alberta Agriculture and Forestry.
“This new hybrid rye is also more resistant to ergot contamination. This fungus is an anti-nutritional factor that can make pigs eat and grow less, and it is the reason why rye is usually not fed to pigs,” she adds.
The trial took place at a commercial grow-out barn, and researchers fed the grower-finisher hogs one of three diets. The first diet consisted of a low level of hybrid rye that replaced one-third of the wheat grain. The second diet was a medium level of hybrid rye that replaced two-thirds of the wheat grain. The third diet consisted of a high level of hybrid rye that replaced all the wheat grain. The high rye diets had about 45% of hybrid rye in the grower phases and up to 63% in the finisher phases.
“What we noticed was that hogs fed the high rye diets ate and grew a bit less than the ones on the low rye diet, but the feed efficiency and carcass traits were similar among the three treatment groups,” explains Smit.
“The feed cost per pig or per kg body weight (BW) gain, and the gross income subtracting feed cost were also not affected by the hybrid rye inclusion level. These results show that hybrid rye can completely substitute wheat grain in grower-finisher diets.”
As for the decrease in feed intake and growth rate when feeding this hybrid, Smit explains why it happened. “The lower feed intake for high rye diets was probably because of higher amounts of non-starch-polysaccharides or viscous fibre in rye than in wheat. This viscous fibre is not woody-type husks like in barley. These non-starch-polysaccharides (NSP) are a bit more like sticky gum - difficult to digest, but water-soluble. Given time, they will be digested. Certain feed enzymes may speed up the breakdown of these gummy compounds and make them available for digestion.”
As for a possible solution, she says that they also looked at the effect of adding a NSP enzyme to the hybrid rye diets. “We noticed that the enzyme did not affect feed intake, but it did tend to improve growth rate. It also improved feed efficiency in the high rye diets. We therefore now recommend including NSP feed enzymes in diets with a high level of hybrid rye.”
Smit adds that it makes senses to feed hybrid rye instead of wheat when rye is cheaper than wheat. “Generally, if rye sells for about $10 per metric tonne less than wheat, the hybrid rye will come into the ration. The reduced feed cost will make up for the fact that hogs need to stay on farm one or two more days to reach market weight.”
Her takeaway message from this trial is that hybrid rye can completely substitute wheat grain in grower-finisher hog diets without affecting feed efficiency, carcass traits, feed cost per pig, feed cost per kg BW gain and income-over-feed cost.
“We do recommend adding a NSP enzyme to high rye diets to improve growth performance and feed efficiency. Assuming rye yields 100 bushels per acre versus wheat 70 bushels per acre - so a 30-bushel difference - and assuming 660 lb. of feed per hog, of which 60% - so 400 lb. - is either rye or wheat, it means that we can feed four more hogs per acre with rye than with wheat.”
To learn more about this trial, contact Miranda Smit: