Selection for bull fertility: a review

Abstract

Fertility is a critically important factor in cattle production because it directly relates to the ability to produce the offspring necessary to offset costs in production systems. Female fertility has received much attention and has been enhanced through assisted reproductive technologies, as well as genetic selection; however, improving bull fertility has been largely ignored. Improvements in bull reproductive performance are necessary to optimize the efficiency of cattle production. Selection and management to improve bull fertility not only have the potential to increase conception rates but also have the capacity to improve other economically relevant production traits. Bull fertility has reportedly been genetically correlated with traits such as average daily gain, heifer pregnancy, and calving interval. Published studies show that bull fertility traits are low to moderately heritable, indicating that improvements in bull fertility can be realized through selection. Although female fertility has continued to progress according to increasing conception rates, the reported correlation between male and female fertility is low, indicating that male fertility cannot be improved by selection for female fertility. Correlations between several bull fertility traits, such as concentration, number of spermatozoa, motility, and number of spermatozoa abnormalities, vary among studies. Using male fertility traits in selection indices would provide producers with more advanced selection tools. The objective of this review was to discuss current beef bull fertility measurements and to discuss the future of genetic evaluation of beef bull fertility and potential genetic improvement strategies.

Genetic parameters of semen quality traits and genetic correlations with service sire nonreturn rate in Nordic Holstein bulls

“…Therefore, selective breeding to improve semen quality traits has the potential to increase conception rate, thereby lowering cost per pregnancy. Additionally, improving semen quality has the potential to increase the quality and quantity of semen produced by genetically superior sires, hence promising wide availability of semen from elite sires at a more reasonable price (Butler et al, 2019).…”

The Effect of Stress on Reproduction and Reproductive Technologies in Beef Cattle—A Review

“…Among the main causes of reduced reproductive efficiency in beef, we find infectious diseases [ 1 , 2 ], such as bovine viral diarrhea [ 3 , 4 ], infectious bovine rhinotracheitis [ 5 ], trichomoniasis due to Tritrichomonas foetus [ 6 , 7 ] and campilobacteriosis due to Campylobacter foetus spp. [ 6 ]; inadequate nutritional programs [ 8 ] which revealed undernutrition and imbalanced nutrition; bull infertility [ 9 ], revealing the need to confirm a bull’s breeding soundness before introducing it for natural mating in a beef herd [ 10 ]; genetics, with some aspects of reproductive performance in beef cows proving more than 50% heritable [ 11 ] and inadequate animal welfare [ 12 ]. In contrast to the extensive research on infectious diseases, inadequate nutrition and bull infertility, less is known about how animal welfare interferes with reproductive performance [ 13 , 14 , 15 ].…”

Cellular and Molecular Insights Into the Etiology of Subfertility/Infertility in Crossbred Bulls (Bos taurus × Bos indicus): A Review

“…Even though infertility is common in both crossbred males and females, infertility in a male can have a formidable effect since semen from a single bull is used for artificial breeding of thousands of cows ( Kastelic, 2013 ). Female fertility received much attention and was enhanced through assisted reproductive technologies, as well as genetic selection, whereas bull fertility was largely ignored ( Butler et al, 2020 ). Globally, a significant proportion of reproductive failure is attributable to bull subfertility due to poor semen quality ( DeJarnette et al, 2004 ).…”