Studies On The Reproductive Performance Of Boer Bucks

The reproductive performance of Boer bucks kept in Linyou county (Se-deficient area), Shaanxi Province under pasture land and trough-fed with some concentrate were observed in order to obtain a scientific feeding mode and a rational selecting method to these animals.The explored content included the relationships between serum reproductive hormone level and growth and semen quality of male boer kids, seasonal variation of serum reproductive hormone level of Boer bucks, relationship between body mass index and semen quality and serum reproductive hormone levels and the effects of selenium on reproductive hormones and sperm quantity of Boer bucks etc. The experimental methods and the results were as follows:1. The serum T,E2,FSH,LH levels of 20 Boer male kids at same age were determined by radioimmunoassay. The results showed that serum T level of male kids rised rapidly at age of 7 months and the level peaked at age of 9 months(380.49 pg/ml), but this value was only 25.97% of youth bucks. The serum E2,FSH and LH levels of all of male kids were low,that is , the male kids were not sexual maturity and shoulds not be mated.2. The serum reproductive hormone levels of 25 Boer bucks during different seasons were determined by radioimmunoassay. The results showed that the Serum hormone levels of all of bucks during reproductive season were higher than that during nonreproductive season , especially for the T level , the values of Boer bucks at age of 1~1.5,2~3.5 and 4~5 years old during reproductive season were 8.2,6.2 and 7.63 times that of the nonreproductive season respectively. The serum T, E2 , FSH and LH levels of 1~1.5 years old Boer bucks were low during reproductive season. Compareing with 2~3.5 years old Boer bucks , the T level of the older bucks were lower ,but the FSH and LH level were higher, and the serum E2 level was significantly higher than others(P< 0.05). The serum T level of 2~3.5 years old Boer bucks was the highest (1395.91pg/ml). In summary, 2~3.5 years old Boer bucks were in reproductive vigorous stage and were of good breeding capacity during reproductive season.3. Semen qualialty of 24 Boer bucks at age of 2-3 year old and their reproductive hormone level were been evaluated separately by Computer and Automated System Association (CASA) and radioimmunoassay.The result showed that the ejaculate volume of bucks at BMI<60kg/m~2 (groupⅠ) was lower, it was only 0.79±0.03 ml. The index value from bucks at BMI>80kg/m2 (groupⅢ) was the most(1.02±0.07 ml), but their sperm density and sperm motility were lower. The middle ejaculate volume(0.95±0.12 ml ) was from groupⅡ(BMI=60~80kg/m~2), their sperm density was 28.32±4.08 billion /ml, it was higher obviously than that of groupⅠ(31.93b±2.06 billion /ml)and groupⅢ(25.96a±3.23 billion /ml)(P<0.05, meanwhile, there were higher sperm motility and lower abnormal sperm morphology in groupⅡ.The serum T,E2 and FSH levels of backs at pooler condition (groupⅠ)were lower. The ejaculate volume was affected by the three indexes. In summary, it was important for bucks to keep a good condition.4. 16 three-years old Boer bucks managed in same pasture land and trough-fed with some concentrate were divided into treatment and control group randomly. The treatment group was injected with Sodium selenite vitamin E injection 4 ml (i. e.0.46 mg/ml), and control group was injected with nothing. The serums were prepared to determine T, E2, FSH and LH at 10th- , 20th- and 30th-day after treatment, and the semen of all of bucks were collected and quality of semen was detected at 30th-day. The results showed that the serum Se level of of bucks in treatment group rose rapidly and the highest peak appeared at 20th-day after injection. The serum T, serum FSH and sperm motility of treatment group were higher than that of control group ((P<0.05), but there was no significantly difference on serum E2, serumLH, ejaculate volume and sperm density between two groups (P>0.05). so it was necessary for the bucks kept in Se-deficient area to get supplementation Se.