Effects of Soy Protein Concentrate in Starter Phase Diet on Growth Performance, Blood Biochemical Indices, Carcass Traits, Immune Organ Indices and Meat Quality of Broilers

SIMPLE SUMMARY: It is well known that early nutrition plays an important role in determining changes in later physiology. Therefore, in order to promote the early growth of broilers, it is necessary to feed diets with high concentration of nutrients and high digestibility in the early stage after hatching. Since soy protein concentrate (SPC) has the characteristics of low content of antinutritional factors (ANFs), high digestibility and high amino acid content, we evaluated whether supplementation of SPC in starter diet could promote the later growth of broilers without changing the diets nutritional level (the same Metabolizable energy (ME), crude protein (CP) and amino acids (AAs)). The results showed that supplementing SPC in starter diet could improve the growth performance, carcass traits and immune organ indices of broilers. The results are very promising and SPC can be considered as a starter diet additive for commercial use. However, the mechanism of adding SPC in starter diets to improve broiler performance needs further study. ABSTRACT: Soybean meal (SBM) is high in antinutritional factors (ANFs), which is not conducive to the starter growth of broilers. The purpose of this study was to investigate the effects of soy protein concentrate (SPC) in starter diet on growth performance, carcass traits, meat quality, immune organ indices and blood biochemical indices of broilers. A total of 384 1-day-old Arbor Acres (AA) male broilers (46.05 ± 0.37 g) with similar body weight were randomly divided into 4 groups with 8 replicates in each group and 12 broilers in each replicate. The experiment was divided into three phases: in starter phase (1–10 d), birds were fed a corn-SBM-based basal mash diet (control) and the basal diet was supplemented with SPC at 4% (SPC4), 8% (SPC8), 12% (SPC12). In the grower phase (11–21 d) and the finisher phase (22–42 d), the birds in all four treatment groups were fed the same diets. The results showed that the body weight was significantly increased in the SPC8 and SPC12 groups of broilers at 10 d and 42 d (p < 0.05). The average daily gain was significantly increased in the SPC12 group of broilers at 1–10 d and 1–42 d (p < 0.05). The average daily feed intake was significantly increased in the SPC8 and SPC12 groups of broilers at 1-10 d (p < 0.05). The feed conversion rates at 1–42 d (p = 0.055) tended to decline in the SPC12 group. The carcass yield and the thymus indices were significantly increased in the SPC12 group of broilers at 42 d (p < 0.05). Alanine aminotransferase (ALT)/aspartate aminotransferase (AST) tended to decline in SPC12 group at 10 d (p = 0.055) and total protein (TP) tended to increase in the SPC12 group at 42 d (p = 0.080). The contents of total cholesterol (T-CHO) and high-density lipoprotein (HDL) were significantly elevated in the SPC12 group of broilers at 42 d (p < 0.05). In conclusion, dietary inclusion of 12% SPC as a starter diet can be recommended due to the positive effects on broilers.