The use and application of hybrid rye in diets for weanling, growing, and reproducing swine: A review

Rye is a cereal grain that has not been used in diets for pigs in large amounts due to concerns of ergot contamination, anti-nutritional factors that reduce growth performance, and poor palatability. However, the cross-pollinating characteristic of rye has resulted in development of hybrid rye varieties that are resilient to environmental stressors, have less ergot contamination, and have greater yield potential compared with conventional population varieties, which has increased its use as an alternative ingredient in pig diets. This review summarizes current knowledge about energy and nutrient composition, digestibility of energy and nutrients, and recommended inclusion rates of hybrid rye in diets for weanling, growing, finishing, and reproducing swine. Effects of feeding hybrid rye on growth performance, intestinal health, and meat quality are also discussed. As a cereal grain, hybrid rye contains around 600 g/kg starch, which has an ileal digestibility of 0.90–0.95 by pigs. Hybrid rye has a greater concentration of soluble dietary fiber compared with wheat and corn, and the apparent total tract digestibility of total dietary fiber is greater than 0.65, which is also greater than in other cereal grains. Hybrid rye has greater concentrations of most standardized ileal digestible amino acids than corn, but less than in barley and wheat. Metabolizable energy is also less in hybrid rye than in corn and wheat because of the greater concentration of dietary fiber. Hybrid rye has the greatest intrinsic phytase activity among cereal grains, which results in greater standardized total tract digestibility of P compared with other cereal grains. Hybrid rye can replace up to 600 g/kg of barley, wheat, or corn in diets for weanling pigs, and up to 800 g/kg in diets for growing-finishing pigs without negatively affecting growth performance, animal health, or carcass quality. Likewise, hybrid rye may replace at least 500 g/kg of corn in diets for sows without negatively impacting reproductive performance. The dietary fiber in hybrid rye may influence the intestinal microbiome of pigs, potentially improving intestinal health and immune response. In conclusion, hybrid rye can be used in diets for pigs at all stages of production.