The Effect of Dilution Rate on the Livability and the Fertility of Bull Spermatozoa Used for Artificial Insemination

Abstract

Bull spermatozoa diluted with yolk-citrate diluent showed a decreased ability to maintain their motility during storage at 5° C. with each increase in rate of dilution. Dilution rates of from 1 part of semen to 1 part of diluter, up to 1 part of semen to 32 parts of diluter were used. Semen possessing higher numbers of spermatozoa, a large percentage of which were actively motile on initial examination, survived storage at the higher dilutions better than did semen of lower spermatozoa count and lower initial motility. In field studies, when the semen was diluted at a predetermined rate based on the spermatozoa count and the percentage of motile spermatozoa in each semen sample, no differences were found in fertility between semen diluted at the rates of 1 part of semen to 2 parts of diluter up to 1 part of semen to 14 parts of diluter. Over 3900 inseminations were involved. In an investigation designed to eliminate arbitrary selection of the rate of dilution to be used for any satisfactory semen sample, no difference was found in fertility for semen diluted at the rates of 1 part Of semen to 4, 6, 8, 10, 12, or 16 parts of diluter. Semen at all dilution rates was used for as long as 6 to 8 days after collection. No observable differences were noted in the maintenance of fertility for the several dilution rates during the first 4 days of storage. For diluted semen used, longer than this period, the number of inseminations was too few on which to base conclusions. © 1943, American Dairy Science Association. All rights reserved.