Effects of heat treatment of soy protein isolate on the growth performance and immune function of broiler chickens

Abstract

This study was conducted to evaluate the effects of oxidative modification of soy protein isolate (SPI) after exposure to heat on the growth performance and immune function of broilers. The SPI was heated in an oven at 100°C for 1, 4, and 8 h, respectively, and resultant oxidative status was evaluated. A total of 320 one-day-old Arbor Acres chickens were randomly divided into 4 treatment groups with 8 replicates of 10 birds, and fed diets supplemented with the native SPI or 1 of the 3 heat-treated SPI for 21 d. The results showed that heat exposure of SPI for 4 and 8 h caused an increase in protein carbonyl (P < 0.05), and a simultaneous decrease in sulfhydryl and free amine groups (P < 0.05) compared with native SPI. The BW of broilers fed diets supplemented with SPI heated for 8 h were significantly lower than that of broilers fed diets supplemented with native SPI (P < 0.05). Compared with native SPI, heat-treated SPI (heated for 8 h) diminished liver weight at 14 d (P = 0.01), spleen (P < 0.01) and bursa (P < 0.05) weights at 21 d; and the content of IgG in serum and duodenal mucosa of broilers (at 14 d) was decreased when diets supplemented with heat-treated SPI (heated for 8 h; P < 0.01). No significant differences were observed in the mucosa secretory IgA contents of broilers among the treatment groups (P > 0.05). Compared with native SPI, a significant increases were observed in the content of adrenocorticotropic hormone and cortisol in serum of broilers fed the heat-treated SPI (heated for 8 h) at 21 d (P < 0.05); and the myeloperoxidase activities in serum (at 14 d) and mucosa of broilers were increased when diets supplemented with heat-treated SPI (heated for 8 h; P < 0.05). The present study suggests that protein oxidation of SPI is induced by heating, and oxidized protein may negatively affect the immune function of broilers.

Digestive evaluation of soy isolate protein as affected by heat treatment and soy oil inclusion in broilers at an early age

“…; Wu et al . ), and protein oxidation might be accelerated by lipids (Boatright & Hettiarachchy ; Cucu et al . ).…”

“…; Wu et al . ). Moreover, proteins are utilized in processing various products often rich in lipids, thus interactions between the proteins and lipids inevitably occur (Cucu et al .…”

“…A previous study in our laboratory has provided evidence that heat‐oxidized SPI adversely affected growth performance of broilers (Wu et al . ). However, there is little information on whether oxidized protein induced by soybean oil would cause changes in growth performance and digestive function of broilers.…”

Effect of gut stress induced by oxidized wheat gluten on the growth performance, gut morphology and oxidative states of broilers

“…Wu et al. () also found a simultaneous decrease in sulfhydryl groups in oxidized soy protein isolate (SPI) and fed broilers with oxidized SPI leading to a lower final BW. In the present study, OG significantly decreased growth performance of birds.…”

Potential use of Lentinus squarrosulus mushroom as fermenting agent and source of natural antioxidant additive in livestock feed

“…Prolonged exposure to air, heat, sunlight and poor storage conditions are among the factors promoting oxidative rancidity in the feed. The drawbacks of long‐term supply of deteriorated feed to animals are documented in several studies, which include low growth performance, weak immune system, increase mortality rate and producing animal‐based products with lower nutritional quality . Moreover, oxidised feeds are considered to be toxic, hence this has provoked fears about the safety of food products derived from the affected animals.…”