Heat-induced protein oxidation of soybean meal impairs growth performance and antioxidant status of broilers.

This study aimed to evaluate the impact of oxidative modification on soybean meal (SBM) proteins after exposure to different heating times, and the effects of the oxidized SBM on the growth performance [average daily feed intake (ADFI), average daily gain (ADG), and feed to gain ratio (F: G)], oxidative redox status [(reactive oxygen species (ROS), total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), and protein carbonyl (PC)]. A total of 400 one-day-old Arbor Acres chicks were randomly divided into 5 treatment groups with 8 replicates of 10 birds each. Birds in the control group (CON) were fed diet containing non-heated SBM, and those in the treatment groups were fed SBM heated at 100°C for 1, 2, 4, and 8 h, for 42 d. Heated SBM (HSBM) showed a relatively higher PC content in vitro. The ADG decreased, whereas the F:G increased linearly with an increase in heating time during the starter (days 1 to 21), grower (days 22 to 42), and the overall growth phases (days 1 to 42; P < 0.05). However, the ADFI decreased linearly only during the grower phase (P < 0.05). The plasma, liver, and jejunum ROS levels, MDA concentrations, and PC contents increased linearly (P < 0.05) in broilers fed HSBM. Furthermore, the TAC in the plasma and jejunum, and the total SOD and GSH-Px activities in the plasma, liver, and jejunum decreased linearly (P < 0.05) in broilers when feeding HSBM. (P < 0.05). The mRNA level of Nrf2 in the liver and jejunum was lower (P < 0.05) in broilers fed diet containing the SBM after 8 h heat-treatment than in those fed the CON diet at days 42. This study suggested that heat-induced protein oxidation of SBM could decrease growth performance and impair antioxidant status of broilers.

The protein oxidation of soybean meal induced by heating decreases its protein digestion in vitro and impairs growth performance and digestive function in broilers.

1. The soybean meal (SBM) was heated at 100°C for 1, 2, 4 and 8 h, respectively, and their resultant oxidative status was evaluated. 2. A total of 400 one-day-old Arbor Acres broilers were randomly divided into 5 treatments with 8 replicates of 10 birds each, and fed with diets containing non-heated SBM (NHSBM) or 1 of 4 heated SBMs (HSBMs, SBMs heated at 100°C for 1, 2, 4 and 8 h, respectively) for 42 d. 3. The contents of carbonyl in the SBMs were both linearly and quadratically increased, whereas the nitrogen solubility index, and in vitro digestibility of crude protein (CP) and dry matter (DM) in the SBMs were both linearly and quadratically decreased as heating time increased (P < 0.05). The concentrations of sulfhydryl and total sulfhydryl in the SBMs were linearly decreased as heating time increased (P < 0.05). 4. The average daily gain was linearly decreased while the feed conversion ratio (FCR) was linearly increased in broilers as heating time of dietary HSBMs increased during both d 22-42 and d 1-42 of study (P < 0.05), though FCR of broilers during d 22-42 study were unaffected when the heating time of dietary HSBMs was 1 h (P > 0.05). The serum glucose concentration and the activity of trypsin at d 42, and the apparent total digestibility of CP and DM were all linearly reduced in broilers when heating time of dietary HSBMs increased (P < 0.05). However, 1 h HSBM has a numerical higher CP and DM digestibility than NHSBM. The serum urea nitrogen contents were both linearly and quadratically increased at both d 21 and 42 (P < 0.05), and relative pancreas weight was linearly increased at d 42 in broilers as heating time of dietary HSBMs increased (P < 0.05).

Effects of dietary methionine on growth performance, meat quality and oxidative status of breast muscle in fast- and slow-growing broilers.

This experiment was conducted to investigate the effects of dietary methionine (Met) on growth performance, carcass traits, meat quality and oxidative status of breast muscle in fast- (Arbor Acres, AA) and slow- (Partridge Shank, PS) growing broilers from 1 to 42 d of age. The broilers were divided into a 2 × 3 factorial design with 6 replicates per treatment. Diets were formulated to contain low (LM, 0.35 and 0.31% during 1 to 21 and 22 to 42 d), adequate (AM, 0.50 and 0.44%) and high (HM, 0.65 and 0.57%) Met, respectively. The main effects showed that the AA broilers had superior (P < 0.05) growth performance and carcass traits compared with those of the PS broilers. The breast muscle of the AA broilers had lower (P < 0.05) drip loss and malondialdehyde (MDA) content but higher (P < 0.05) cooking loss and glutathione peroxidase (GPX) activity than that of the PS broilers. Compared with the LM diets, the AM and HM diets increased (P < 0.05) 42-d BW, ADG, eviscerated yield and breast muscle yield only in the AA broilers. The AA broilers fed the HM diets had higher (P < 0.05) pH but lower (P < 0.05) L*, cooking loss and ether extract content in breast muscle than those fed the LM diets. Compared with the LM diets, the HM diets resulted in strain-dependent changes (P < 0.05) in muscle oxidative status, with total antioxidant capacity (T-AOC) increased in the AA broilers, GPX activity increased and MDA content decreased in the PS broilers, and superoxide dismutase (SOD) activity increased in both strains of broilers. No differences were observed between the AM and HM diets except for T-AOC in breast muscle. In conclusion, the LM treatment negatively affected broiler growth performance, carcass traits, meat quality and oxidative status of breast muscle in a strain-dependent manner, particularly in the AA broilers, whereas the HM treatment had limited effects compared to the AM treatment.

Interaction of plasma proteins with cytochromes P450 mediated metabolic reactions: inhibition by human serum albumin and alpha-globulins of the debrisoquine 4-hydroxylation (CYP2D) in liver microsomes of human, hamster and rat.

The effect of human serum albumin (HSA), alpha1-acid glycoprotein (alpha1-AGP), and alpha- and gamma-globulins on the in vitro metabolism of debrisoquine in human, hamster and rat liver microsomes was studied. Interaction of albumin with cytochrome P450 mediated phenytoin metabolism has been reported. Since plasma protein binding of phenytoin is high, in the present study a weakly protein bound drug, debrisoquine, was studied. Debrisoquine is a substrate of CYP2D6. The debrisoquine 4-hydroxylation was measured using a radio-TLC method. Among the four plasma proteins, alpha-globulins had the strongest inhibitory effect on the debrisoquine 4-hydroxylase activity. The inhibition with 2% alpha-globulins was 42+/-18% for human and higher for hamster and rat liver microsomes (65-71%). HSA had less effect than alpha-globulins. In the presence of HSA, the decrease in activity was between 18 and 35% for all liver microsomes studied. The debrisoquine 4-hydroxylase activity was not significantly changed by alpha1-AGP or gamma-globulins. Using an ultra-filtration method, the protein binding of debrisoquine to 4% HSA, 0.5% alpha1-AGP, 2% alpha-globulins and 2% gamma-globulins was found to be 22, 20, 22 and 5%, respectively. Since the observed inhibition is inconsistent with level of protein binding, it appears, particularly in the case of alpha-globulins, that the plasma proteins interact with CYP2D directly.