Effects of exogenous protease supplementation on endogenous trypsin activity and gene expression in broilers

Effect of a novel alkaline protease from Bacillus licheniformis on growth performance, carcass characteristics, meat quality, antioxidant capacity, and intestinal morphology of white feather broilers

BACKGROUND

The present study was conducted to investigate the effects of dietary novel alkaline protease from Bacillus licheniformis on the growth performance, meat quality, antioxidant status and intestinal morphology of broilers. In total, 4000 broilers were randomly assigned into five groups and treated with normal control, normal control + 100 mg kg-1 protease, normal control + 200 mg kg-1 protease, normal control + 300 mg kg-1 protease and normal control + 400 mg kg-1 protease.

RESULTS

Supplementing protease impacted final body weight (linear, P = 0.003; quadratic, P = 0.006) and decreased feed conversion rate (linear, P = 0.036) in broilers. Moreover, dietary protease significantly increased breast muscle rate (linear, P = 0.005; quadratic, P = 0.021) and decreased drip loss (linear, P < 0.001; quadratic, P < 0.001). In addition, dietary protease notably increased protein digestibility (linear, P = 0.001; quadratic, P = 0.006) and trypsin activity (linear, P = 0.002; quadratic, P = 0.009) in jejunum. Light microscopy revealed that the jejunum villi in the 300 mg kg-1 and 400 mg kg-1 groups exhibited greater height and a denser arrangement compared to those in the control group. The addition of protease decreased malondialdehyde content (linear, P < 0.001; quadratic, P < 0.001) and increased total antioxidant capacity (linear, P = 0.001; quadratic, P < 0.001) in pectoral muscles.

CONCLUSION

The results of the present study suggest that dietary novel alkaline protease from B. licheniformis improved growth performance by affecting trypsin activity, protein digestibility, antioxidant capacity and intestinal health. © 2024 Society of Chemical Industry.

Effects of crude protease produced by Bacillus subtilis (MAFIC Y7) on growth performance, immune indices, and anti-inflammatory responses of broilers fed soybean meal- or cottonseed meal-based diets

A strain of Bacillus subtilis (MAFIC Y7) was isolated from the intestine of Tibetan pigs and was able to express high protease activity. The aim of this study was to characterize the proteases produced by MAFIC Y7, and to investigate the effects of protease addition on growth performance, ileal amino acid digestibility, and serum immunoglobulin and immune factors of broilers fed SBM-based diets, or on growth performance, carcass characteristics, and intestinal morphology of broilers fed CSM-based diets. B. subtilis (MAFIC Y7) expressed protease showed its optimal enzyme activity at 50 °C and pH 7.0. The coated crude enzyme (CCE) showed greater stability at pH 3.0 than its uncoated counterpart. Experiment 1 was conducted with six diets based on three levels of crude protein (CP)-CPlow, CPmedium, and CPhigh-with or without CCE. In CPlow, CCE increased gain:feed (G:F) (days 1 to 21, days 1 to 42) by 8%, 3%, respectively, and enhanced apparent ileal digestibility (AID) of crude protein and lysine (on day 42) by 8.8%, 4.6%, respectively, compared with diets containing no CCE (P < 0.05). CCE increased G:F from days 1 to 21 from 0.63 to 0.68, improved G:F and average daily gain (ADG) during days 1 to 42, and enhanced AID of crude protein, lysine, cysteine, and isoleucine on day 42 compared with the unsupplemented treatments (in CPmedium, P < 0.05). CCE increased serum IgA (on day 21), serum IgA and IgG and increased serum IL-10 (on day 42), but decreased serum tumor necrosis factor-α (TNF-α; on day 21), and serum IL-8 and TNF-α (on day 42) compared with unsupplemented treatments. At CPhigh, CCE decreased serum levels of IL-6 and TNF-α (on day 21), and IL-8 and TNF-α (on day 42) compared with unsupplemented treatments (in CPhigh, P < 0.05). In experiment 2, CSM-based diets with two lysine-to-protein ratios (5.2% or 5.5%) with or without CCE. In the high Lys diet (5.5% Lys:protein), CCE increased ADG and G:F, increased carcass, but decreased abdominal fat compared with the unsupplemented treatment (P < 0.05). In the 5.2% Lys:protein dietary treatment, CCE improved duodenal villus height compared with the unsupplemented treatment (P < 0.05). Supplementation of protease produced by MAFIC Y7 was associated with lower inflammatory responses in SBM diets (CPmedium or CPhigh) and improved ADG in broilers fed CPmedium or CPhigh. The proteases improved ADG and the efficiency of CSM use when the ratio of Lys to protein was 5.5%.

Effects of a monocomponent protease from Bacillus licheniformis on broiler performance, digestibility, and carcass yield

Two experiments were carried out to evaluate the effects of protease addition to the diet of broilers at a higher level (1× or 2×) than the nutritional value proposed for the enzyme. The first experiment, 1280 day-old chicks (Cobb500®) were randomly allocated (randomized block design, 2×2+1 factorial arrangement), five treatments, eight replicates containing 32 birds/replicate. Treatments consisted: control diet without protease (CD); CD + 1× nutritional value of the enzyme (CDM1); CD + 2× nutritional value of the enzyme (CDM2); CDM1 + protease; and CDM2 + protease. The experimental period was 42 days. The mean weight (AFW), feed intake (FI), weight gain (WG), feed conversion, and carcass yield were evaluated. Significant differences were observed for AFW, WG, FI, abdominal fat yield, and feet percentage in the carcass. In the second experiment, 120 Cobb500® chicks at 14 days of age were allotted in a completely randomized design, 2×2+1 factorial arrangement, five treatments, six replicates with four birds/replicate. The treatments were consistent with the first experiment. Significant improvements in the nitrogen balance were observed for the broilers that received protease. The use of the enzyme tested is recommended with the recommended nutritional matrix, improving the zootechnical indices of broilers.

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

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.

The effect of protease on growth performance, nutrient digestibility, and expression of growth-related genes and amino acid transporters in broilers

During the course of this trial, our team assessed the influence of protease upon the growth performance, the nutrient digestibility, and the expression of growth-related genes and amino acid transporters within the liver, muscle, and small intestines of broilers. During the first step, our team allocated 600 broilers into four dietary treatments for a period of 35 days in order to measure the growth performance and nutrient digestibility of the broilers selected. The separate treatments contained 10 replicates (15 birds per replicate). The treatments were composed of: 1) CON, basal diet; 2) T1, basal diet + 0.03% protease; 3) T2, basal diet + 0.06% protease; and 4) T3, basal diet + 0.09% protease. Next, the broiler chick sample tissue was harvested from the CON and T3 groups in order to conduct gene expression analysis following the feeding trials the broilers underwent. Our team discovered that the broilers fed protease diets possessed increased body weight and an average daily gain, but conversely, had lower feed conversion ratios when their dietary protease levels increased from 0% to 0.09% (p < 0.05). Additionally, significant linear improvements were identified among the nutrient digestibility of dry matter, crude protein, energy, and amino acids within broilers supplied with protease diets when contrasted and compared with broilers supplied with the basal diet (p < 0.05). In addition, the gene expression of the genes IGF1, IGF2, GH, and LEP in the liver, and the genes MYOD1 and MYOG in the breast muscles, was significantly increased after broilers were fed with a protease diet as compared to broilers that subsisted on a basal diet (p < 0.05). Protease supplementation also raised the expression levels within these amino acid transporters: SCL6A19, SLC7A1, SLC7A7, SLC7A2, SLC7A6, SLC7A9, and SLC15A1, located in the small intestine, when compared to the basal diet (p < 0.05). Our results suggest that protease supplementation in their diet improved the growth performance of broilers via an increase in the expression growth-related genes within broiler liver and muscle tissue. In addition, protease supplementation enhanced broiler digestibility via the upregulation of amino acid transporter expression within the small intestine.

Effects of dietary protein levels and protease supplementation on growth performance, carcass traits, meat quality, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet

This study aimed to investigate to the effects of dietary CP levels and protease supplementation on growth performance, carcass traits, meat quality, nutrients utilization, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet. A total of 960 14-day-old male ducks were weighed and randomly allotted to a 2 × 5 factorial arrangement of 10 treatments with 6 replicate pens per treatment and 16 ducks per pen fed to 49 D of age. Experimental factors included five dietary CP levels ranging from 13.5 to 17.5% and with or without protease (200 mg/kg) supplementation. Between day 28 to 34, the digestible and metabolizable trials were performed. Significant CP × protease interactions (P < 0.05) on breast meat yield, DM, energy and nitrogen utilization, as well as standardized ileal digestibility values of 7 amino acids were observed. Regardless of protease supplementation, ducks fed 13.5, 14.5, and 15.5% CP had a poorer (P < 0.05) growth performance and breast meat yield than ducks fed with 16.5 and 17.5% CP. Ducks fed 13.5% CP had a positive effect (P < 0.05) on meat quality, dietary DM, energy and nitrogen utilization as well as standardized ileal digestibility of amino acids. Protease supplementation increased (P < 0.05) DM and phosphorus retention and decreased (P < 0.05) shear force of breast meat, regardless of CP level; when CP = 14.5%, protease significantly increased (P < 0.05) breast muscle yield. The optimal CP requirement without or with protease supplementation for BWG and FI were 17.02 or 16.53% and 16.64 or 16.75%, respectively, based on linear broken-line regression.

Evaluation of novel protease enzymes on growth performance and nutrient digestibility of poultry: enzyme dose response

Two experiments were conducted to evaluate 3 novel proteases in broilers. In experiment 1, 600 male, Cobb 500 broilers were allocated to 1 of 12 experimental diets (5 birds/pen and 10 replicates/diet). A control (C) diet was formulated to be adequate in all nutrients. Proteases 1, 2, or 3 were added to this diet at 3 doses (1x, 3x, or 9x) in a 3 × 3 factorial arrangement of treatments. The factorial was augmented with 2 treatments of phytase at 500 or 1,500 FTU/kg added to the C diet. In experiment 2, 2,050 male Ross 308 broilers were allocated to 1 of 10 experimental diets (25 birds/pen and 9 replicates/diet). A C diet was formulated to be adequate in all nutrients. Protease 1, 2, or 3 was then added to the C diet at 3 doses (1x, 2x, or 4x) in a 3 × 3 factorial arrangement of treatments plus the C. In experiment 1, birds fed phytase gained more (P < 0.05) than birds fed protease, but neither were different than birds fed the C. Supplementation of 9x dose of any protease resulted in a reduction (P < 0.05) in BWG when compared with birds fed 1x dose of protease or phytase at 500 or 1,500 FTU/kg. Feed conversion ratio was improved (P < 0.05) in birds fed phytase compared with birds fed the C diet. Nitrogen digestibility was greater (P < 0.05) in birds fed protease 1 when compared with birds fed protease 2. Birds fed the 1x dose of protease or 500 FTU/kg of phytase had a greater (P < 0.05) N digestibility than birds fed 3x dose of protease. In experiment 2, protease supplementation significantly reduced (P < 0.05) BWG when compared with birds fed the C from hatch to 35 D post-hatch. Protease supplementation did not improve broiler growth performance or N digestibility above that of a nutrient adequate control diet or a diet supplemented with 500 FTU/kg of phytase.

Influence of low-protein and low-amino acid diets with different sources of protease on performance, carcasses and nitrogen retention of broiler chickens

A 42-day experiment was conducted with 625 1-day-old male Hubbard chickens to evaluate the performance, carcass traits, nitrogen retention and economics of broiler chickens fed low protein and amino acid diets supplemented with different protease sources. Treatments included positive (PC) and negative (NC) controls (PC at 19.3% protein vs NC at 18.8% protein), with NC containing 7% less digestible amino acids. The other three treatment groups were based on the NC diet supplemented with 0.05% Cibenza® DP100 (CB), 0.02% Ronozyme® (RZ) or 0.02% Winzyme pro plus (WZ). Birds fed the PC, CB and WZ diets achieved the heaviest bodyweight compared with those fed the NC diet at end of the experiment. Total feed intake of birds fed the PC diet was higher (P < 0.05) than that of birds fed the NC diet. Feed conversion ratio was numerically significantly (P = 0.005) improved with all tested groups in comparison with NC throughout the experiment. European production index was similar (P > 0.05) among birds fed the PC, NC, RZ or WZ diets. All carcass parameters studied, including dressing, heart, gizzard, giblets, chest meat, thigh meat and abdominal fat percentages, were not significantly (P > 0.05) affected by feeding on the different sources of protease. Broilers fed the PC diet or diets formulated with all protease sources had higher (P < 0.05) nitrogen retention than did birds fed the NC diet. The supplementation of protease to low-protein and low-amino acid diets resulted in higher profit margin in broilers. It is concluded that supplementing exogenous protease to broiler diets containing low protein and amino acids improved the growth performance, feed utilisation, carcass traits, nitrogen retention and net returns of broiler chickens.