Two hundred four broilers (1-d-old) were randomly allocated to 4 treatments, each of which had 3 pens of 17 chicks per pen and were used to investigate the effects of beta-mannanase (Hemicell) on growth performance and immunity. The chicks received the same basal diet based on corn-soybean meal and Hemicell was added to the basal diet at 0, 0.025, 0.05, and 0.075%, respectively. Weight of each replicate was determined at wk 0, 3, and 6 of age. There were no significant differences in average feed intake in the 0- to 3-wk and 0- to 6-wk periods, and no differences in serum IgA, or IgG concentrations. However, the addition of Hemicell significantly increased (P < 0.05) weight gain in the 4- to 6-wk and 0- to 6-wk periods. Feed conversion for the 0.025 and 0.05% groups was significantly greater (P < 0.05) than for the control group in the 4- to 6-wk and 0- to 6-wk periods. Hemicell significantly increased (P < 0.05) the serum IgM concentration in 3- and 6-wk-old broilers. Proliferation of T lymphocytes in 6-wk-old broilers for the 0.05% group was also improved (P < 0.05) significantly. The results indicate that Hemicell may improve growth performance and immunity of broilers.
This study was conducted to evaluate the effect of monochromatic light stimuli during embryogenesis on breast muscle growth, chemical composition, and meat quality of male broilers. Fertile broiler eggs (Arbor Acres; n = 1,320) were preweighed and randomly assigned to 1 of 3 treatment groups in 3 modified incubators: 1) control group (in dark condition), 2) monochromatic green light group (560 nm), and 3) monochromatic blue light group (480 nm). The monochromatic lighting systems sourced from light-emitting diode lamps and were equalized at the intensity of 15 lx at eggshell level. After hatch, 120 male chicks from each group were placed in 6 replicates with 20 birds each. All of the birds were housed under white light (30 lx at bird-head level) with a light schedule of 23L:1D. At 21, 35, and 42 d of age, BW and breast muscle weight in the green light group were significantly increased compared with birds in the blue or dark groups (P < 0.05). The breast muscle weight and breast muscle percentages in birds incubated under green light were significantly elevated by 50.39 g (0.76%) and 54.07 g (1.20%) than those in the dark condition or blue group at 42 d of market age (P < 0.05), respectively. In the green light group, feed intake during 0~42 d was higher than that in the other 2 treatment groups (P < 0.05); feed conversion ratio during 0~35 and 0~42 d were lower than that in the dark condition (P < 0.05). No significant differences in the contents of breast moisture, CP, crude fat, and crude ash among all groups were observed (P > 0.05). Green light stimuli tended to increase cooking loss (P = 0.08) and L* value of 24-h meat color (P = 0.09). These results suggest that green light stimuli during embryogenesis enhanced the posthatch BW of male broilers, increased breast muscle growth, and improved the feed conversion ratio, but it did not cause any noticeable changes in breast chemical composition or overall meat quality characteristics.
Beta-hydroxy-β-methylbutyrate (HMB), the metabolite of leucine, plays an important role in muscle protein metabolism. To investigate the effect of dietary HMB calcium (HMB-Ca) on growth performance, breast muscle development, and serum parameters in broiler chickens, a total of two hundred seventy 1-d-old Arbor Acres male broiler chicks were randomly allotted into 3 dietary treatments supplemented with 0, 0.05%, or 0.1% HMB-Ca during the starter (1 to 21 d) and grower (22 to 42 d) period. The results showed that broilers fed 0.1% HMB-Ca diet had higher ADG during the starter or the whole period, and gain 148 g more BW than the chicks fed the control diet at 42 d of age (P < 0.05). At 21 d of age, birds receiving 0.1% HMB-Ca had more breast muscle yield, less abdominal fat than the control, and more dressing percentage than birds fed the control or 0.05% HMB-Ca diet (P < 0.05). At 42 d of age, 0.1% HMB-Ca increased breast muscle yield than the control and decreased abdominal fat compared with the control or 0.05% HMB-Ca group (P < 0.05). In comparison with the control, feeding 0.1% HMB-Ca increased the triiodothyronine, thyroxine, triiodothyronine/thyroxine ratio and decreased the serum uric acid level at d 21 (P < 0.05). At 42 d of age, serum thyroxine level was elevated in the 0.05% HMB-Ca treatment, and the uric acid concentration was significantly decreased by the 0.1% HMB-Ca-supplemented diet (P < 0.05). Dietary HMB-Ca did not affect the growth hormone or insulin content. This study suggested that dietary supplementation of HMB-Ca improved growth performance, stimulated the breast muscle development, and decreased the abdominal fat deposition in broiler chickens, and the favorable effects were more pronounced in the starter phase. The growth promotion effect of HMB-Ca may be partly related to the increased serum thyroid hormones in broiler chickens.
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