• Korean Journal of Poultry Science
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• v.49 no.4
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• pp.239-246
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• 2022

This study was conducted to investigate the effects of dietary γ-aminobutyric acid (GABA) and a probiotic mixture on egg production and quality, blood parameters, and stress levels (corticosterone) in Hy-Line parent stock during summer in Korea. A total of 105 Hy-Line parent stock aged 24 weeks were randomly divided into three groups, each containing thirty-five birds: control, γ-aminobutyric acid (GABA), and probiotics (1 × 10⁸/g Bacillus licheniformis, 1 × 10⁷/g Lactobacillus plantarum, and 1 × 10⁷/g Corynebacterium butyricum). The hens were fed a diet containing 50 ppm GABA or 0.1% probiotics for 6 weeks. Compared with the control group, the hen-day egg production, egg mass, and feed conversion ratio over the total period were significantly higher in the probiotic group (P<0.05). In contrast no significant differences were detected among groups with respect to egg weight, albumen height, Haugh units, yolk color, shell thickness or shell strength. Similarly, no significant difference were observed among groups with regards to biochemical profile (total cholesterol, triglyceride, glucose, total protein, aspartate aminotransferase, alanine aminotransferase, albumin, and inorganic phosphorus). However, compared with the control group, we did detect significant reductions in corticosterone levels in the GABA and probiotics groups (P<0.05). On the basis of our findings in this study, it would appear that dietary GABA and probiotics can alleviate heat stress in Hy-Line parent stock, with probiotics in particular being found to promote significant improvements in the hen-day egg production, egg mass, and feed conversion of laying hens during the summer season in Korea.

• Animal Bioscience
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• v.35 no.12
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• pp.1871-1880
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• 2022

Objective: The primary goal was to identify the effectiveness of chemical or biological additives in delaying the deterioration of early-harvested wilted rye silage after exposure to air. Methods: Rye harvested as a whole plant at the early heading stage was wilted for 24 h. The wilted forage was divided into treatments including sodium diacetate (SDA) at 3 (SDA3) and 6 g/kg (SDA6), Lactobacillus plantarum (LP), L. buchneri (LB), or their equal mixture (LP+LB) at 1×10⁶ colony-forming unit/g fresh matter. Results: After 60 d of conservation in 20-L silos, lactic acid was greater in LP and LP+LB silages than other treatments (102 vs 90.2 g/kg dry matter [DM]). Acetic acid was greatest in SDA6 (32.0 g/kg DM) followed by LB (26.1 g/kg DM) and was lowest in LP treatment (4.73 g/kg DM). Silage pH was lower with microbial inoculation and the lowest and highest values were observed in LP and untreated silages, respectively. After 60 d, neutral detergent fiber concentration was lowest in SDA6 silages, resulting in the greatest in vitro DM digestibility (846 g/kg DM). Aerobic stability was longest in SDA6 (176 h) followed by LB treatment (134 h). Instability after aerobiosis was greatest in LP silages (68 h), about 8 h less than untreated silages. After aerobic exposure, yeast and mold numbers were lowest in SDA6 silages, resulting in DM loss minimization. Exhaustion of acetic acid and lactic acid after aerobic exposure was lowest with SDA6 but greatest with untreated and LP silages. Conclusion: Treatment of early-cut wilted rye forage with SDA at 6 g/kg resulted in silages with higher feeding value and fermentation quality, and substantially delayed deterioration after aerobic exposure, potentially qualifying SDA at this load for promotion of silage quality and delaying aerobic spoilage of early-harvested (low DM) rye forage.