Use of Hybrid Rye in Diets for Growing and Reproducing Pigs: A Literature Review and Determination of Green-House Gas Emissions.

Scientific Abstract

The first objective of the current work was to conduct a literature review of all published information related to the feeding value to pigs of hybrid rye for swine and to provide feeding recommendations based on the summarized data. The second objective was to conduct an animal experiment to determine greenhouse gas emission from pigs fed diets based on hybrid rye and compare those values to diets containing corn. In the literature review, 54 peer-reviewed manuscripts and 7 abstracts were used to summarize current knowledge about chemical composition and nutrient and energy digestibility in hybrid rye, and conclusions about recommended inclusion levels were also identified. In the animal experiment, a total of 24 pigs (initial body weight: 52.38 ± 2.52 kg) were assigned to 6 calorimeter chambers with 4 pigs per chamber. Chambers were allotted to a replicated 3 × 3 Latin square design with 3 diets, 6 chambers, and 3 periods. Therefore, there were a total of 6 replicates for each diet. Each chamber was equipped with a stainless steel wet-dry feeder, and an auxiliary nipple waterer was in each chamber to ensure free access to water. Fecal and urine materials were quantitatively collected, and gas exchanges were recorded. The statistical model included diet as the fixed effect and chamber and period as the random effects. Linear effects of increasing hybrid rye were analyzed using contrast coefficients. Results of the literature review indicated that the digestibility of phosphorus is greater in hybrid rye than in other cereal grains because of a much greater concentration of intrinsic phytase, but the concentration of digestible energy is less in hybrid rye than in corn and wheat due to a greater concentration of fiber. Hybrid rye can replace up to 65% of corn in diets for weanling pigs, and all corn in growing-finishing diets can be replaced by hybrid rye without negative impacts on growth performance. However, hybrid rye can only replace up to 75% of corn in diets for gestating or lactating sows. Results of the animal experiment indicated that respiratory quotient (RQ) of pigs during the fasted period was not affected, but RQ of pigs during the fed period was reduced (linear; P = 0.047) by increasing hybrid rye in diets. Consumption of O₂ and productions of CO₂ and CH₄ were not affected by dietary treatment. Nitrogen intake was not affected by dietary treatment, but concentration of N in feces was greater (P < 0.020) when corn was completely replaced by hybrid rye. However, digestibility and retention of N and excretion of N in feces and urine were not affected by increasing hybrid rye in diets.