Comparing Soybean Products for Turkeys

An experiment was conducted to investigate the effects of diets containing soybean meal (SBM), soybean protein concentrate (SPC), and soybean protein isolate (SPI) on growth performance and gut function of the young turkey. A total of 812 one-day-old male turkey poults were randomly assigned to four dietary treatments, with seven pens per treatment and 29 birds per pen. The four experimental diets containing SBM, SBM-SPC, SPC, and SPI were isonitrogenous and isocaloric and contained similar amounts of total and water-soluble nonstarch polysaccharides. The content of oligosaccharides differed among the diets and averaged 2.4, 1.9, 0.9, and 0.1% for SBM, SBM-SPC, SPC, and SPI, respectively.

When compared with SBM, birds consuming the SBM-SPC and SPC diets had higher (P < 0.05) final body weight (4.32 vs. 4.45 and 4.46 kg, respectively). Incorporation of SPI as a substitute for SBM resulted in improved feed utilization from 1.76 to 1.67 (P<0.05), but did not affect the final body weight. Significant changes in cecal concentrations of short-chain fatty acids were observed and averaged 130, 103, and 89 µmol/g of digesta for the SBM, SBM-SPC, and SPC diets, respectively. This coincided with the proportional decrease in dietary oligosaccharide content from 2.4 to 0.9% and was further substantiated by a significant decrease in ileum weights. Feeding the SPI diet resulted in the lowest ileal and cecal tissue weights as well as the lowest cecal short-chain fatty acids concentration. There was no effect of diet on digesta pH, viscosity, and mucosal sucrase and maltase activities. Bacterial ?-glucuronidase activity was decreased in the cecum from 0.98 to 0.60 U/g (P=0.08) with decreased dietary oligosaccharide content. The researchers concluded that partial, or almost complete, substitution of SBM with SPC suppressed the fermentation processes in the ceca and enhanced the growth rate. The substitution of SBM with SPI significantly improved feed utilization with no effect on growth rate of poults during this eight-week study.

Jankowski, J. and co-workers. 2009. The effect of diets containing soybean meal, soybean protein concentrate, and soybean protein isolate of different oligosaccharide content on growth performance and gut function of young turkeys. Poultry Sci. 88:2132-2140.