Search

Twenty mature Holstein bulls (3 to 10 yr old) were used to test the effect of two semen collection regimens on spermatozoal output, post-thaw percentage spermatozoal motility, and time needed to make the collections/week. For both regimens, six ejaculates/wk were collected using either three ejaculates/d, 2 d/wk, or two ejaculates/d, 3 d/wk. A three-period switchback experimental design was used. Each collection period for which measurements were taken was 3 wk and was preceded by a 2 wk period of acclimation. The total number of spermatozoa harvested per week was not significantly different (P>.05): 33.2 × 109when the bulls were collected two ejaculates 3 d/wk, compared with 33.9 × 109three ejaculates 2 d/wk. Post-thaw progressive spermatozoal motility was 50.3 and 52.1% (P>.05), respectively. The average time per week to collect each bull was 73.6 and 83.7 min (P<.05), respectively.

Spermatozoa frozen in .5-ml French straws at concentrations designed to give approximately 2, 4, 6 or 8 × 106progressively motile spermatozoa per insemination unit after thawing in iced, ambient or 37 C water were evaluated for fertility and quality. The overall 90-day nonreturn rate for spermatozoa thawed in 37 C water was higher (P<.05) than that for spermatozoa thawed in either ambient temperature water or iced water (69.6, 66.0 and 65.0%, respectively). Technicians showing a below-average nonreturn rate had a greater (P<.05) beneficial response with the 37 C thawing procedure than did technicians showing above-average nonreturn rate (14.1 vs1.9%, respectively). All semen evaluations—(1) progressive motility, (2) presence of an intact acrosome (total and uninjured), (3) acrosin activity, (4) glutamic-oxaloacetic transaminase activity remaining in the spermatozoa and (5) capacity of spermatozoa to pass through a sephadex filter—indicated that spermatozoa thawed in 37 C water were superior (P<.05) to spermatozoa thawed in iced water. For the same characteristics, spermatozoa thawed in iced water were not different (P>.05) from those thawed in ambient temperature water. Incubation at 37 C magnified differences among thawing temperatures when spermatozoa were evaluated for progressive motility, presence of an intact acrosome (total and uninjured) and acrosin activity remaining in spermatozoa. The percentage of spermatozoa with a particular viability characteristic was not (P>.05) correlated with fertility for semen thawed at 37 C. However, the number of spermatozoa inseminated that had the viability characteristic was positively correlated (P<.05) with fertility. None of the correlation coefficients was high, probably because of large variations due to sample size. The relationship between seminal viability characteristics and fertility was best explained by an exponential model. There was an increase (P<.05) in nonreturn rate as the number of viable spermatozoa inseminated increased. However, the higher nonreturn rate at the 37 C thawing procedure could not be obtained with either the ambient or iced water merely by increasing the number of viable spermatozoa inseminated.

Worldwide interest in semen preservation of ram, boar and stallion has increased in recent years as indicated by the surge of hundreds of scientific reports. Since primary interests have been on freeze preservation, this paper will deal exclusively with the various aspects of frozen semen, and only materials which are pertinent to this area concerning the storage of liquid semen. Success in freezing ram and stallion semen has been reported since the late 1950's and boar since the early 1970's. Results have been relatively inconsistent and generally poor for these species. One purpose of this paper is to examine and review the many variables in materials and procedures that form the obstacles to greater success. Another is to report the present fertility that investigators have been able to achieve thus far and, perhaps, the last objective is to study why the fertility results in artificial insemination using frozen semen in sheep, swine and horses have been poor.As one might realize, the advantages of artificial insemination (AI) are many. The greatest advantage is the opportunity to spread superior germ plasm through the widespread use of carefully tested and selected males. Artificial insemination has been used very successfully in cattle. It is hoped through research and improved techniques that the use of frozen semen and A.I. might become practical in sheep, swine and horses, also.Although many of the materials, methods, procedures and problems for semen preservation of these species are similar, others are not. Therefore each will be dealt

Bull spermatozoa were pellet frozen on dry ice in a TES buffer containing combinations of egg yolk and glycerol to determine which component of an extender afforded cryoprotection to the spermatozoa. Neither buffer nor buffer plus glycerol protected sperm cell motility in the absence of egg yolk, while sperm cells frozen in egg yolk buffer in the absence of glycerol had 24% postthaw motility (P< .05). Egg yolk was found to be the main cryoprotective agent, but there was a synergistic effect between glycerol and egg yolk in providing the greatest postthaw survival (40%) of sperm cells (P< .05).Purification of egg yolk to determine which fractions were affording protection was conducted using ultracentrifugation, Biogel filtration and Sephadex filtration. Purification procedures and agar gel electrophoresis indicated that a large lipoprotein complex could be isolated free of contaminating migrating proteins. The lipoprotein complex was the low density fraction (LDF) of egg yolk. In the absence of glycerol this complex protected motility of sperm cells during the freezing process.

Three trials were conducted to examine the effects of dilution and glycerol addition on boar spermatozoa utilizing increased extracellular GOT as a determinant of cellular damage. Both dilution of boar semen with Tris-tricine extender and glycerol addition resulted in increases in extracellular GOT. It was also demonstrated that glycerol damaged the spermatozoa regardless of when or how it was added, and the damage was proportional to the glycerol concentration. Dilution of glycerolated spermatozoa with glycerol-free extender resulted in further damage perhaps caused by lysis as demonstrated with bovine erythrocytes.