The present study was conducted to determine the non-return versus actual conception rate in buffaloes and Cows for predicting fertility rate of Bulls. For this purpose 6 Buffalo and 10 Cow Bulls (5 Red Sindhi and 5 Sahiwal) were selected from the Bulls of different breeds and species maintained at the Artificial Insemination Section, College of Animal Husbandry, Lahore.
During the period from 1955 to 1970 Artifical Insemination were carried out in buffaloes and Cows with good qualities semen of these selected bulls maintained at the Centre. All the semen samples were checked for physical and microscopic examinations. Extension of semen was made in Milk Glycerol Extenders containing pencillin and streptomycin and preserved from 3 to 4 days in refrigerator at 5oC. All Inseminations were mostly carried out by Intra-cervical methods and only one ml of extended semen was used.
In the present study data for first inseminations in the buffaloes and cows of selected bulls were only considered. All the non-return rate were compiled on the basis of 30, 60, 90, 120, 60-90 and 90-120 days intervals with the Ist service. The results of actual conception rate for first insemination were also considered for comparison. The data were analysed by the analysis of variance and Duncan's Multiple Range test was also applied to find out the results. The studies revealed that:
The non-return percentages between species (Buffalo and cow) fpr first insemination of different intervals were found to be significant except at 90 days interval. Similarly the non-return percentages among different specie for first inseminations were found significant.
The differences in non-return percentages for different breeds (Buffalo Red Sindhi and Sahiwal) for first insemination at 30,60,90,120 and 60-90 days intervals were found non significant but at 90-120 days interval were significant.
Highly significant differentes in non-return percentages were observed between bulls of Sahiwal Breed. It was significant between bulls of buffalo breed, while non significant differences were found between bulls of Red Sindhi breed.
The actual conception percentage for inseminations in Buffalo Bulls was lower as compared to cow bulls,but the conception rate for Sahiwal bulls was obtained higher than with Red Sindhi Bulls.
Highly significant differences were obtained in conception rate on the basis of non-return as compared to actual pregnancy test.
Significantly lower conception rates were recorded with natural service as compared to that obtained with artificial insemination.
Based on the results of this study, it may be concluded that more reliance can be placed on the conception rates based on non-return percentages at 120 days interval or above.