Testicular Size and Scrotal Circumference in Speckle Park

CSPA BULLETIN

TESTICAL SIZE AND SCROTAL CIRCUMFERENCE

The Directors of the Canadian Speckle Park Association set in 1999 the standard for the minimum scrotal circumference of a yearly Speckle Park bull.  This standard remains in effect in 2017:

“Minimum scrotal circumference required of a Speckle Park bull at 1 year of age

is 30 cm.”

This 30 cm minimum has become pretty much the accepted standard in the cattle industry.  In the Speckle Park industry this is also the accepted standard even though one too regularly sees bulls offered in public auctions with less than the minimum 30 cm scrotal circumference.  Although some may justify selling these bulls as an acceptable practice because they are under one year of age or simply on the basis of “people want to buy them,” there is no justification for offering bulls over14 month old with 29 cm scrotal circumference in public sales.  Sellers and buyers need to bear in mind that this practice does little to enhance the reputation of Speckle Park among commercial cattlemen and does little to improve the breed’s reputation for below standard  scrotal development.

TheWestern Canadian Association of Bovine Practitioners offers this “Information for Producers” on the reverse side of their Breeding Soundness Evaluation which we all use.  This is reproduced here with permission of their office.

Information  For Producers

High reproductive efficiency is economically 5-10 times as important as rate of gain or carcass quality. Therefore, fertility is the foremost concern in bull selection. High fertility in bulls requires soundness in 3 basic areas: sex drive and serving ability, physical soundness and semen quality. Usually there is no assessment of sex drive in routine bull evaluations and some mating problems cannot be detected by a chute-side physical inspection. Therefore, producers must determine on their own whether bulls have adequate sex drive and serving ability.

The first semen a young bull produces has very poor quality and is low in sperm numbers. It takes 3 to 4 months from the onset of sperm production until a young bull reaches maturity and is able to produce good semen. In general about 45%, 75% and 95% of bulls are mature at 12, 14, and 16 months of age, respectively.

Scrotal circumference measurement is a highly accurate indicator of testis mass. Large testes are important for normal sperm production and adequate numbers of sperm for the high breeding pressure of short breeding seasons. In addition, large testes are strongly positively correlated with early onset of puberty in heifer offspring, early breeding of heifers, and high female lifetime productivity. Since scrotal circumference is highly heritable, pro- ducers should be careful to avoid bulls with small testes. In yearlings, scrotal circumference increases at about 1.5, 1.1, 0.8, and 0.4 cm from 11-12, 12-13, 13-14, 14-15 months of age, respectively.

The following tables show the average scrotal circumference for bulls according to age and breed. Bulls measured under cold conditions, or with excessive body condition, may have inflated measurements by 1 to 2 cm. The minimum recommendations in Table 3 eliminate bulls in about the bottom 10% for scrotal circumference.