1548
Effects of rumen-protected -aminobutyric acid on immune function and antioxidant status in heat-stressed dairy cows

Monday, July 21, 2014
Exhibit Hall AB (Kansas City Convention Center)
Jianbo Cheng , State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
Nan Zheng , Ministry of Agriculture - Milk and Dairy Product Inspection Center (Beijing), Beijing, China
Xianzhi Sun , State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
Deng-pan Bu , State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
Long Pan , State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
Jiaqi Wang , Ministry of Agriculture - Milk and Dairy Product Inspection Center (Beijing), Beijing, China
Abstract Text:

This experiment was conducted to investigate the effects of rumen-protected γ-aminobutyric acid (GABA) on immune function and antioxidant status in heat-stressed dairy cows. Sixty Holstein dairy cows (141 ± 15 DIM, 35.9 ± 4.3 kg of milk/d) were randomly assigned to 1 of 4 treatments according to a randomized complete block design. Treatments consisted of 0, 40, 80, or 120 mg GABA/kg DM from rumen-protected GABA. The trial lasted 10 wk. The average temperature-humidity indices at 0700, 1400 and 2200 h were 78.4, 80.2 and 78.7, respectively. Blood samples were collected from all of animals via tail vein before the morning feeding on d 0, 21, 42, and 56. Data were analyzed by MIXED model procedure of SAS. Concentrations of immunoglobulin (Ig) A (0.18 and 0.25 vs 0.16 mg/mL) and IgG (64.62 and 62.14 vs 32.08 μg/mL) increased (P < 0.05) in cows fed 80 or 120 mg/kg GABA, while IgM level showed no difference (P > 0.05) when compared with control cows. Compared with control, concentrations of IL-2 (10.84 and 9.37 vs 6.37 ng/mL) and IL-4 (76.72 and 85.64 vs 56.63 pg/mL) were higher (P < 0.05) in cows fed 80 or 120 mg/kg GABA, and the IL-6 level was higher (124.24 vs 77.53 pg/mL; P < 0.05) in cows fed 120 mg/kg GABA, tended to be higher (89.42 vs 77.53 pg/mL; P < 0.10) in cows fed 80 mg/kg GABA. The TNF-α level was higher (68.50 and 80.82 vs 49.18 fmol/mL; P < 0.05) in cows fed 80 or 120 mg/kg GABA, and tended to be higher (62.29 vs 49.18 fmol/mL; P < 0.10) in cows fed 40 mg/kg GABA. The proportions of CD4+ (9.26 and 9.88 vs 7.03%) and CD8+ (6.41 and 6.26 vs 5.15%) T lymphocyte were higher (P < 0.05) in cows fed 80 or 120 mg/kg GABA compared with control, but ratio of CD4+/CD8+ was not different (P > 0.05) among treatments. Compared with control, the activities of SOD (9.59 and 9.52 vs 8.54 U/mL) and T-AOC (6.11 and 5.64 vs 3.20 U/mL) increased (P < 0.05) in cows fed 80 or 120 mg/kg GABA, but the activities of GSH-Px and MDA were not affected (P> 0.05) by GABA supplementation. These results indicate that rumen-protected GABA supplementation to heat-stressed dairy cows can improve the immune function and enhance antioxidant activity.

Keywords: γ-amino butyric acid, immune function, antioxidant activity