Growth performance and amino acid digestibility responses of broiler chickens fed diets containing purified soybean trypsin inhibitor and supplemented with a monocomponent protease

Abstract

Trypsin inhibitors ( TI ) resident in soybeans affects protein utilization. While heat treatment influences residual TI, it simultaneously affects the structure and solubility of the soybean proteins and confounds any response to exogenous proteases. Using purified TI, the effect of exogenous protease to TI can be dissociated from changes in the soybean protein. Thus, the current study was designed to evaluate the growth performance and protein utilization responses of broiler chickens to purified TI and exogenous protease. Soybean meal ( SBM ) was preanalyzed for basal TI (2,996 TIU/g SBM), formulated into nutritionally adequate experimental diets to contain 1,033 TIU/g diet, and purified TI was added at 9,000 TIU/g diet. A total of 320 Cobb-500 broiler chicks were allocated to 4 diets, each with 8 replicate cages and 10 birds per replicate. The experimental diets were arranged as a 2 × 2 factorial with factors being dietary TI (1,033 or 10,033 TIU/g) and exogenous protease (0 or 15,000 PROT/kg). On day 7, 14, and 21 posthatching, protease supplementation improved the BW gain ( P < 0.01) and gain to feed ratio ( P < 0.05) of birds. On day 14 and 21 posthatching, the relative weight of pancreas increased ( P < 0.05) with added TI but was reduced ( P < 0.001) with protease supplementation. Apparent ileal digestibility of all amino acids, except methionine, decreased ( P < 0.001) with added TI but increased ( P < 0.05) with protease supplementation. Jejunal MUC-2 was downregulated ( P < 0.01) and SCL7A-2 was upregulated ( P < 0.05) by protease supplementation. Duodenal trypsin and chymotrypsin activities reduced ( P < 0.05) with added TI but increased (P < 0.01) with protease supplementation. Exogenous protease produced longer villi ( P < 0.05) and deeper crypts ( P < 0.01) in the jejunal tissue. In conclusion, dietary addition of purified TI negatively affects nutrient utilization by broiler chickens. Furthermore, the study showed that the efficacy of the exogenous protease might be independent of dietary TI concentration.

Contribution of purified soybean trypsin inhibitor and exogenous protease to endogenous amino acid losses and mineral digestibility

“…The primary objective of this study was to evaluate the direct contribution of TI to EAA losses in broiler chickens, and whether this is affected by exogenous protease supplementation. The impact of soybean TI on growth performance and nutrient digestibility in broiler chickens is widely reported ( Clarke and Wiseman,2005 ; Erdaw et al, 2017 ; Aderibigbe et al, 2020 ). Currently, there are no published data on the effect of TI on endogenous secretion in birds.…”

“…Birds were individually tagged, weighed, raised in heated battery brooders (model SB 4 T; Alternative Design Manufacturing, Siloam Springs, AR) and fed a nutritionally adequate corn-SBM based diet (210 g/kg CP; 3,100 kcal/kg ME) until d 20 post hatching. Temperature and lighting were maintained as previously described by Aderibigbe et al (2020) . Twelve hours prior to experimental diet allocation, birds were fasted to empty the gut of residual dietary N. Subsequently on d 21 post hatching, using a 2 × 2 factorial arrangement, with 2 concentrations of dietary TI (0 or 8,000 TIU/g) and exogenous protease (0 or 15,000 PROT/kg; Ronozyme ProAct, DSM Nutritional Products, Kaiseraugst, Switzerland) the chicks were allotted to 4 experimental NFD ( Table 1 ) in a randomized complete block design, with BW as a blocking factor, resulting in 8 blocks per treatment.…”

“…The pancreas was collected from 2 median bird per replicate cage, frozen in liquid nitrogen and stored at ‒80°C until required for enzyme assay. Enzymes activities were determined as previously described by Aderibigbe et al (2020) using a commercially available assay kit (Sigma Chemical Co, St. Louis, MO). Crude mucin and sialic acid concentration were determined based on methods previously described by Horn et al (2009) .…”

“…This may lead to increased TI intake which affects dietary protein digestion and amino acid utilization in nonruminants by inhibiting the activation of the proteolytic enzymes in the gut ( Rawlings et al, 2004 ; Erdaw et al, 2017 ). On the other hand, exogenous protease supplementation is a widely accepted strategy to improve dietary protein utilization in nonruminants ( Clarke and Wiseman, 2005 ; Erdaw et al 2017 ; Aderibigbe et al, 2020 ). Additionally, exogenous protease has been shown to improve EAA recovery in birds ( Cowieson and Roos, 2016 ).…”

Progress on Gut Health Maintenance and Antibiotic Alternatives in Broiler Chicken Production

“…Nontoasted full-fat soya beans increase subclinical NE lesions in the gut compared with toasted full-fat soya beans ( 40 ). The high content of trypsin inhibitors negatively affects nutrient utilization in the diets of broiler chickens ( 41 ).…”