A lot of attention is directed towards the female’s side of reproduction. If human couples can’t conceive children, most people think, “What is wrong with her?” Little do they know, there are a lot of potential fertility problems on the male side as well. The Centers for Disease Control and Prevention (2013) conducted a national study in 2002 with data showing that approximately 11% of 15 – 44 year old women in the U.S. have some sort of pregnancy difficulties. That same report also shows that 7.5% of men under the age of 45 have fertility problems as well.
That statistic of males having a role in low conception rates is also true for cattle. For both beef and dairy producers alike, it is essential to study the male side to increase fertilization rates in your herd. Chenoweth (2005) states that the purpose of the bull is to provide the female cow with attainable spermatozoa and to successfully deliver them into the vagina during copulation to fertilize the ova. But, what happens if the bull is unable to? Beef producers don’t want to cull an expensive bull. Some questions that the producer might think are: “Is this defect heritable? What caused the bull to be infertile? Is this a long term effect? Will it go away after a period of time?” All of these questions can be answered with the ever changing reproduction knowledge that animal scientists are receiving.
Physical Scrotum Infertile Conditions
The testis of the bull are a very important organ to study when one talks about fertility among males. It has been said that there is a positive correlation between scrotum size and number of fertile sperm. It’s known that with increase in age of the bull you have an increase in scrotal circumference, yielding higher and more matured sperm in the semen (Menon et al., 2011). Some standard numbers for scrotal circumference for the Bos taurus beef breeds are 30 cm with Bos indicus (warmer climate) breeds at 28 cm (Ashwood, 2010).
Breeds and scrotal circumference have also shown similarities. Limousin bulls have lower scrotal circumferences. Simmental bulls had the highest SC in 11 to 13 months and 19 to 26 month old animals. Angus and Hereford bulls had the highest SC 13.5 to 18 months and greater than 26 month age groups (Menon et al., 2011). While measuring the bull’s scrotum, adequate feed management should be practiced. If the bull is highly fed, this can lead to an increased in scrotal circumference “by 3-6 cm without increasing testicle size, fertility, and service capacity” (Ashwood, 2010). This higher degree of fatness can also lead to overheating and less fertile sperm.
Other common physical scrotal problems can be present in your bull. If not culled out, the problems can be handed down to offspring. One of these problems is a defective testicle development (hypoplasia) and it occurs in 1.5 to 2 percent of bulls. Hypoplasia can take place on one or both sides, the bull is proven to be sub-fertile, and should...