An Optimal Dietary Selenium Level For 4 To 6 Months Kid Old Cashmere Goats

This trial was conducted to evaluate the effects of dietary selenium on growth performance, antioxidant function and immune function of 4 to 6 months old Cashmere Goats, in order to determine the optimal dietary selenium level for kid Cashmere Goats. 24 wether kid Shanbei Cashmere Goats, which were healthy and had similar weight (14.08±0.61 kg) and age (4 months old), were assigned randomly into four treatments for 60 days. The four treatments were fed with four diets differed in selenium concentration (0.11 mg/kg, 0.21 mg/kg, 0.41 mg/kg, and0.61 mg/kg). The body weight, glutathione peroxidase (GSH-Px) activity and selenium concentration in whole blood, and malondialdehyde (MDA) and IgG concentration in plasma were measured at the beginning of the trial, then the 30th day and the 60th day. At the end of the trial, all the goats were slaughtered and GSH-Px activity, selenium and MDA concentration in liver, muscle, kidney, heart and spleen were determined. The results showed:(1) The dietary selenium had no influence on the average daily gains (ADG) (P>0.05). When the dietary selenium concentration was 0.41mg/kg, goats had the greatest ADG.(2) At the 30th day and the 60th day, GSH-Px activity and selenium in whole blood were increased with dietary selenium level increased. There were significant difference (P<0.05) when the dietary selenium ranged from 0.11 mg/kg to 0.41 mg/kg, while no significant difference were observed from 0.41 mg/kg to 0.61mg/kg. GSH-Px activity and selenium concentration in whole blood were positively correlated with each other.(3) The dietary selenium had no influence on the MDA concentration in plasma of kid Cashmere Goats (P>0.05).(4) At the 30th day, the dietary selenium had no effect on the IgG concentration in plasma of kid Cashmere Goats. At the 60th day, the IgG concentration was increased significantly with the dietary selenium concentration increased (P<0.05).(5) In liver and muscle, both GSH-Px activity and selenium concentration were increased significantly (P<0.05) with dietary selenium level increased from 0.11 mg/kg to 0.41 mg/kg except 0.41 mg/kg to 0.61mg/kg. A positive correlation exists between GSH-Px activity and selenium concentration in tissues of liver and muscle. (6) When the dietary selenium concentration ranged from 0.11 mg/kg to 0.41 mg/kg, the MDA concentration in liver and muscle were decreased correspondingly. While no significant difference were observed from 0.41 mg/kg to 0.61mg/kg. GSH-Px activity and MDA concentration in liver and muscle were negatively correlated with each other.(7)The selenium concentration in kidney, heart and spleen were increased significantly with the dietary selenium concentration increased from 0.11 mg/kg to 0.41 mg/kg except from 0.41 mg/kg to 0.61 mg/kg diet.Based on the results, the dietary selenium content of 0.41 mg/kg may have satisfied the requirements for kid Cashmere Goats to improve antioxidant function, but it is not enough until 0.61 mg/kg diet or more to meet the requirements for them to increase immune function.