The purposes of these studies were to examine the influence on the yield of sex-sorted sperm by the different size of sorting gate and to evaluate factors that affect the purity of sex-sorted sperm. As the sorting gate was expanded, so the yield of bovine sex-sorted sperm using flow cytometry was increased. At the same time, the purity of sex-sorted sperm became low. In addition, though the sorting gates were the same size, the purity of sex-sorted sperm differed among trials. These observations indicated the existence of factors that affect purity besides the size of sorting gate. To examine the yield of sex-sorted sperm, X-bearing sex-sorted sperm from 4 Holstein bulls were produced repeatedly 34 times by 3 flow cytometers. The sizes of sorting gates were fixed at 40–42%, 44%, and 46%. Each yield of sorting gate at 40–42%, at 44% and at 46% was compared. To evaluate factors that affect purity, X- or Y-bearing sex-sorted sperm were produced by one flow cytometer. These trials were repeated 160 times for the sorting of X-bearing sperm and 45 times for the sorting of Y-bearing sperm. Stepwise multiple regression analysis was used to analyse the relationships between the purity of sex-sorted sperm and the following sorting conditions, the percentage of oriented sperm, the percentage of dead sperm, degree of separation between X-bearing and Y-bearing sperm, the size of sorting gate, event rate, drop drive frequency, drop delay value and drop delay accuracy. The highest yield was acquired by sorting gate at 44%. The number of sex-sorted sperm was increased as sorting gate was expanded, however, the purity became low. The purities of the sperm by some trials using sorting gate at 46% were less than our acceptable lowest purity that was 90%. So that those sperm must be discarded. Therefore the yield of sorting gate at 44% was greater than sorting gate at 46%. Stepwise multiple regression analysis revealed that the factors for increasing purity of X-bearing sex-sorted sperm were the percentage of oriented sperm (P < 0.001), the degree of separation between X-bearing sperm and Y-bearing sperm (P < 0.001), the drop delay accuracy (P < 0.001), the event rate and the drop drive frequency, and the factor for decreasing purity of X-bearing sex-sorted sperm was the size of sorting gate (P < 0.001). On the other hand, the factors for increasing purity of Y-bearing sex-sorted sperm were the percentage of oriented sperm (P < 0.01), the degree of separation between X-bearing sperm and Y-bearing sperm (P < 0.01) and the event rate (P < 0.05), and the factor for decreasing purity of Y-bearing sex-sorted sperm was the size of sorting gate (P < 0.01). From these results, it can be concluded that the purity of sex-sorted sperm was not depend on simply by size of sorting gate but was more completely explained by other sorting conditions.
The constraints of good governance practice in national solid waste management policy (NSWMP) implementation: A case study of Malaysia
