Study On The Effect Of γ-aminobutyric Acid On Laying Performance In Pigeons And Approach To The Mechanisms

This study is conducted to determine the effects ofγ-aminobutyric acid (GABA) on the laying performance in pigeons, and further study the mechanism from endocrine, immunity and antioxidant.A total of 96 pairs pigeons aged 360 d were randomly divided into four groups with three replications and eight pairs in each treatment in 40 days trail. The treatments were designed in a single factorial arrangement, and were as follows:basal diet with 0(control group),20 (GroupⅠ),40 (GroupⅡ), and 80 (GroupⅢ) mg/kg GABA, respectively. After the feeding trail, six pairs in each group were selected and slaughtered. Blood and tissue samples were collected for corresponding indices.The results showed as the follows:(1)Results showed thatγ-aminobutyric acid could improve the laying performance of pigeons. Compared with the control, the number of individual egg production per month and total egg weight increased by 13.66%(P>0.05) and 13.49% (P>0.05) in 20 mg/kg group. However, all the three levels of GABA had no effect on laying interval whereas it was decreased by 6.76%(P>0.05),10.08%(P>0.05) and 9.55%(P>0.05).(2) The analysis of biochemical parameters in serum indicated that the concentration of serum total protein increased by 2.29%(P>0.05) and 12.10% (P>0.05) respectively in 20 and 40 mg/kg GABA groups, whereas decreased by 7.76%(P>0.05) in 80 mg/kg GABA group compared with the control. The albumin level in 80 mg/kg GABA group significantly increased by 22.82%(P>0.05). The blood urea nitrogen concentration in 40 mg/kg GABA group decreased by 16.44% (P>0.05) compared to the control. The triglyceride concentration decreased by 2.11% (P>0.05),15.79%(P>0.05) and 21.11%(P>0.05) respectively in 20,40 and 80 mg/kg GABA groups. The serum glucose concentration respectively decreased by 2.07% (P>0.05),7.53%(P<0.05) and 9.06%(P<0.05) in 20,40 and 80 mg/kg GABA groups. All the levels of GABA had no effect on the concentration of serum calcium and phosphorus and on the activity of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase.(3) The analysis of hormones in serum indicated that the prolactin concentration decreased by 11.52%(P>0.05),26.84%(P<0.05) and 21.78%(P＜0.05) respectively in 20,40 and 80 mg/kg GABA groups. The level of FSH in every treament had no significant difference, whereas increased by 9.06%(P>0.05) in 40 mg/kg GABA group.(4) Results showed that there was no significant difference in serum IgM level in each treament. Compared with the control, the concentration of serum IgA and IgG respectively increased by 39.53%(P＜0.05) and 62.68%(P＜0.05) in 20 mg/kg GABA group. The concentration of serum IgA, IgG and C3 increased by 48.84%(P＜0.05), 63.38%(P<0.05) and 45.45%(P＜0.05) in 40 mg/kg GABA group. The concentration of serum IgA and IgG increased by 62.79%(P＜0.05) and 85.92%(P<0.05) respectively in 80 mg/kg GABA group, whereas the concentration of IgM and C4 decreased by 2.33%(P>0.05) and 9.09%(P>0.05) in 80 mg/kg GABA group.(5) The results of antioxidant analysis indicated that the concentrations of serum MDA respectively increased by 9.43%(P>0.05),1.95%(P>0.05) and 6.71%(P>0.05) in 20,40 and 80 mg/kg GABA groups. The activities of SOD and GSH-Px had no significant difference in every treatment. The MDA content of heart significantly decreased by 34.94%(P<0.05),36.14%(P<0.05) and 40.96%(P<0.05) in 20,40 and 80 mg/kg GABA groups. The MDA content of kidney and liver were not affected in every treatment. Compared with the control, the SOD activity of liver and heart respectively increased by 2.30%(P>0.05) and 45.76%(P＜0.05), however the SOD activity of kidney decreased by 23.18%(P＜0.05). The GSH-Px activity in liver increased by 30.68%(P<0.05),30.38%(P＜0.05) and 30.25%(P<0.05) respectively in 20,40 and 80 mg/kg GABA groups. The GSH-Px activity in heart increased by 25.30%(P＜0.05) in 40 mg/kg GABA group compared with the control. The activities of kidney GSH-Px in every treatment had no significant difference.(6) The results showed that:Compared with the control, the total protein content of liver increased by 6.22%(P>0.05),14.05%(P>0.05) and 13.85%(P>0.05), and the albumin content of liver increased by 14.66%(P>0.05),20.96%(P＜0.05) and 16.01% (P<0.05) respectively in 20,40 and 80 mg/kg GABA groups. The GTP activity of liver decreased by 24.59%(P＜0.05) and the GOT activities of kidney and heart decreased by 6.55%(P>0.05) and 3.38%(P>0.05) in 40 mg/kg GABA group. The GTP activities of kidney and heart were not affected in each treatment.(7) The results of egg quality analysis showed that the content of protein, cholesterol and fat in eggs were not affected in every treatment. The contents of methionine, isoleucine and leucine decreased by 34.07%(P<0.05),11.49%(P＜0.05) and 6.88%(P<0.05) in 40mg/kg GABA group. The contents of cystine, methionine, isoleucine and tyrosine decreased by 14.43%(P＜0.05),34.07%(P<0.05),10.73% (P<0.05) and 15.76%(P<0.05) in 80 mg/kg GABA group. The total contents of amino acid in egg decreased by 1.85%(P>0.05),5.86%(P>0.05) and 5.33%(P>0.05) in 20, 40 and 80 mg/kg GABA groups.(8) The analysis of fallopian tube micro-morphology that the fallopian tube plicas in three levels of GABA groups were taller than the control. The plicas were appeared neat arrangement in the GABA groups under light microscope observation.The results indicated that:①GABA can improve the laying performance by decreased the prolactin concentration when it was fed into die to laying pigeons. 40mg/kg GABA was the optimal dosage under this research condition.②GABA could enhance the capacity of protein synthesis in liver and promote the deposition of protein.③GABA could enhance the immune function by increasing the concentration of serum immunoglobulin and complement and the antioxidant capacity by increasing the activities of antioxidant enzymes in tissues.④GABA could improve the fallopian tube morphology, relieve the functions recession.