Dietary winter hybrid rye minimally influences performance and carcass characteristics of organically-raised growing-finishing pigs

This study evaluated the utility of winter hybrid rye as a partial replacement for corn in an organic pig production system. Winter hybrid rye replaced 50% of corn in diets for growing-finishing pigs raised organically to determine pig performance, carcass characteristics, and phosphorus concentrations in fecal samples. A total of 500 pigs (initial body weight = 18.9 ± 2.94 kg) were assigned to either a Control or Rye treatment (50 pigs/pen; 5 pens/treatment) balanced for sex and body weight. Control pigs received a corn-soybean meal diet, while Rye pigs were fed a diet where hybrid rye replaced 50% of the corn in the control diet. Pigs were housed in a hoop barn, with wheat straw bedding provided to Control pigs and rye straw bedding for Rye pigs. Pig performance, including body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and gain efficiency (G:F) were recorded every 28 days. At the end of the trial, carcass traits such as hot carcass weight (HCW), backfat thickness (BF), and loin eye area (LEA) were measured. Feed samples from each dietary phase were analyzed for nutrient composition, including phosphorus and phytic acid concentrations. Fecal samples from 80 pigs (40 Control and 40 Rye) were collected and analyzed for phosphorus and phytic acid concentration. There were no differences in BW, ADG, ADFI, G:F, or fat-free lean percent of carcass between Control and Rye fed pigs (p > 0.05). However, carcass yield and LEA were lower in Rye-fed pigs (p < 0.05). Mortality tended to be lower in Rye-fed pigs (p = 0.082) probably due to random variation, while morbidity was not different between treatments (p > 0.05). Phosphorus concentrations in Rye diets were higher across most dietary phases (p < 0.05), but there were no differences in phosphorus or phytic acid concentrations in the fecal samples between treatments suggesting improved utilization of dietary phosphorus in Rye-fed pigs. In conclusion, replacing 50% of corn with winter hybrid rye in diets for organically-raised growing-finishing pigs did not affect growth performance but reduced carcass yield.