Veterinary Clinics of North America: Food Animal Practice
The Effect of Semen Quality on Reproductive Efficiency
Section snippets
Principles of semen quality and fertility
The concepts of compensable and uncompensable semen quality traits and their interactions with numbers of sperm in the inseminate dose are essential to understanding the relationship of semen quality to fertility (Fig. 1) [1], [2]. Compensable semen quality traits are those that respond to increasing cell numbers per dose with increased fertility, and are generally believed to be associated with measures of sperm viability (ie, motility, acrosomal, cell-membrane integrity, and the like).
Assays of compensable semen quality components
Compensable semen quality attributes are those that influence accessibility of a viable sperm population to the ovum proximal to the time of ovulation. Thereby, assessment of sperm motility is a foundation measure for this component of the spermiogram. Likewise, various tests designed to measure the proportions of live sperm and those that have functional intact membranes would be expected to reflect compensable semen quality attributes. Assessment of these traits, however, is theoretically
Assays of uncompensable semen quality components
As mentioned previously, uncompensable semen quality attributes are those believed to be closely associated with the ability of spermatozoa within a sample to sustain embryo development following fertilization. Therefore, uncompensable traits largely impact the maximum level of fertility that is obtainable from a given semen sample, more than they impact the threshold numbers of sperm required to achieve maximum fertility [2]. Normal sperm morphology is the most routinely measured semen quality
Threshold numbers of sperm per dose
Early research related extension rates for bovine semen to be used in AI supported the concept of threshold numbers of sperm per dose, as proposed by Salisbury and VanDemark [1]. These studies typically revealed that as cell numbers per dose were increased, fertility, as measured by nonreturn rates in the female population, responded in a curvilinear fashion [26], [27], [28]. These studies also indicated that individual bulls/ejaculates vary in the rate or slope of the fertility response and in
The spermiogram in perspective
The complexity of the above interactions often limits the diagnostic value of a given semen evaluation procedure, particularly with respect to the positive fertility diagnosis. As implied by Amann and Hammerstedt [35], the relationships of semen quality to fertility should be investigated for degrees of “association” rather than for degrees of “correlation.” Fertile sperm are those that possess sufficient levels of all known and unknown semen characteristics necessary to achieve fertilization
Summary
The impact of the male or inseminate on reproductive efficiency is the function of a complex series of interactions between numbers of sperm per dose and the ratio and severity of compensable and uncompensable sperm defects in the sample. Because of the correlation among many semen quality traits, screening for one trait often enriches the retained population for multiple attributes; however, these correlations also confound our ability to identify which semen quality attribute is most closely
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Cited by (28)
Angus sire field fertility and in vitro sperm characteristics following use of different sperm insemination doses in Brazilian beef cattle
2020, TheriogenologyCitation Excerpt :Field fertility (P/TAI) of each bull is reported at the top of Table 5 to facilitate comparison. The visual assessment of sperm motility, i.e. subjective motility, is a classic measure of sperm quality [34]. Seidel [31] suggested progressive motility is the most appropriate way to evaluate motility and a good measure of potential fertility.
Sperm head phenotype and male fertility in ram semen
2015, TheriogenologyFertility-associated antigen on Nelore bull sperm and reproductive outcomes following first-service fixed-time AI of Nelore cows and heifers
2012, TheriogenologyCitation Excerpt :McCauley et al. [12], however, reported on the development and validation of a lateral flow cassette for the rapid determination of FAA status in bulls, without the requirement for time-consuming, intensive techniques that must be performed in a research laboratory. Taken together with the realization that identification of novel spermatozoal or seminal attributes associated with male fertility may increase the accuracy of fertility estimation [13], the objective of this research was to use the commercially available lateral flow cassette to help determine whether the presence of FAA on sperm collected from Nelore (Bos indicus) bulls can be used to assess potential fertility of sperm for use at first-service TAI in multiparous Nelore cows and nulliparous Nelore heifers. Ejaculates from Nelore bulls (N = 49; range in age: 2 yr 8 mo to 11 yr) housed at Alta Genetics, Uberaba, MG, Brazil, were collected by artificial vagina.