Canadian Beef Breeds Council

October 18, 2013 Michael Latimer, Executive Director Canadian Beef Breeds Council 165 ‐ 6815 ‐ 8th St. NE Calgary AB T2E 7H7 Email: mlatimer@canadianbeefbreeds.com

Dear Michael, By this letter I would like to provide some clarity regarding WCABP’s decision to amend the minimum scrotal circumference (SC) standards, which are a critical component of the bull breeding soundness examination (BSE). The minimum SC standards were last updated in 2000 and were based on data generated in 1972, 1992 and 1998. If we continue to rely on the old standards, then in some cases the data are 40 years old. To address this issue, Dr. Albert Barth, a board certified Theriogenologist at the Western College of Veterinary Medicine (WCVM), along with Drs. Steve Hendrick and Alvaro Guerra, initiated a study to look at testicular size. Specifically, between 2006 and 2011, bulldata were obtained from 41 veterinary practices in western Canadaalong with bull test stations in Quebec. This provided a database of10,968 bulls, ranging in ages from 1 to 11 years, with most being 1 and 2 year olds. Next, these data were compared to the average scrotal circumference data obtained between 1972–1998, see Table 1.Table 1 shows how SC have increased for all breeds overtime. For example, the previous average SC for Herefords was 31.0 cm,and under the old scoring system a 12 month old bull had to be at least 30 cm to pass. Herefords now average 33.9 cm with the lowest 10% being under 30.8 cm. A similar set of tables was generated for each age class of bulls. Fewer than 10 animals were present in each age group for 10 breeds: Belgian Blue, Brown Swiss, Dexter, Fleckvieh, Maine Anjou, Piedmontese, Red Poll, Shaver, Tarentaise, andTexas Longhorn.

226E Wheeler Street Saskatoon, SK S7P 0A9 Phone: 1-866-269-8387 Fax: (306) 956-0607 Email: info@wcabp.com

Table 1.Comparing average scrotal circumference measurements obtained between 1972-1998 from 12-month old bulls to the most recent data collected between 2006-2010.

Mean SC Mean SC OLD Bottom 10% Bottom 5% Breed 1972‐98 2006‐11 standard New data New data Angus 33.3 34.6 31.0 31.9 31.2 Charolais 32.6 34.6 31.0 31.3 30.2 Gelbvieh 33.6 34.4 32.0 30.8 30.4 Hereford 31.9 33.9 30.0 30.8 30.0 Limousin 30.0 31.5 29.0 29.0 28.0 Shorthorn 32.2 33.0 30.0 31.0 30.0 Simmental 34.5 36.0 32.0 33.0 32.1

Tables 2 and 3 show the OLD and NEW suggested minimum scrotal circumferences.In general, the new recommendations are based on culling the bottom 10% of bulls. Significantly, the new system is also more progressive because it has added a separate age class for 15 month old bulls. The rationale is that testicular growth is very rapid from about 7 to 15 months of age and then rapidly levels off so that ~90% of final testis size is reached by 2 years. The 15 month category creates a fairer system because it no longer lumps 15 month old bulls with the 16‐20 month bulls. As for the other changes, the Simmental, Gelbvieh, Pinzgauer and Brown Swiss had a 1.0 cm reduction for the 21‐30 month category (36 to 35cm); all other age classes remain unchanged. Charolais and Angus now belong with the bulls in the first column and therefore they all moved up 1.0 cm at each age class, except at 21‐30 months. Similarly, Herefords and Shorthorns moved from column 3 to column 2 and hence all moved up 1.0 cm at each age class. All the remaining bull breeds remain largely unchanged except the Limousin, Blonde and Galloway bulls which had a 1.0 cm increase at 21‐30 months.

Age (mo.) Simmental, Gelbvieh, Pinzgauer, Brown Swiss Charolais, Angus, Maine Anjou, Red Poll, South Devon, Holstein Hereford, Salers, Shorthorn, Tarentais Limousin, Blonde d’Aquitaine, Galloway

Texas Longhorn

12 32 31 30 29 28 13 33 32 31 30 29 14 34 33 32 31 30 15‐20 35 34 33 32 31 21‐30 36 35 34 32 32

Table 3.NEW Suggested Minimum Scrotal Circumference (cm)

Age (mo.)

Simmental, Angus, Charolais, Gelbvieh, Pinzgauer, B.Swiss/Braunvieh

Hereford, Shorthorn, Maine Anjou, Red Poll, S. Devon, Holstein

Speckle Park Salers, Tarentais Limousin, Blonde d’Aquitaine, Galloway

Texas Longhorn

12 32 31 30 29 28 13 33 32 31 30 29 14 34 33 32 31 30 15 34.5 33.5 32.5 31.5 30.5 16‐20 35 34 33 32 31 21‐30 35 35 34 33 32

The question that arises from this whole exercise is “why increase the minimum standards”?The reason being is that research shows that SC is highly correlated to daily sperm production and semen quality.Furthermore, estimates of heritability of SC at a year of age range from 0.44 to 0.69, which means selection pressureshould increase the average SC across the industry. More importantly,testicular size is correlated with puberty in female offspring. This correlation was first reported in 1996 wherein bulls with higher EPDsfor SC produced daughters that reached puberty at significantly earlier ages. ABeef Research Progress Report noted an extremely high correlation (‐0.98) between mean yearling scrotal circumference and average age at puberty in heifers (the relationship is negative because larger SC is correlated with a younger age that the heifer reaches puberty). Scrotal circumference is also correlated to age at first breeding (‐0.77), age at first calving (‐0.66) and pregnancy rate (0.66).In short, age at puberty and SC are thought to be the same trait. The WCABP believes that the newlyrecommended standards are founded on science and that continuing to place moderate selection pressure on SC should improve the reproductive potential for all breeds. Some have voiced concerns that there will be no end in sight to veterinarians wanting to increase SC. This, however, is not the case, in fact some breeds had the minimum SC standard decrease in SC by 1.0 cm because there were concerns relating to selecting for too large of testes. Michael, I think that it is fair to say that the science behind the changes is sound; however, the communication on our part to industry has been poor. On behalf of the WCABP, I apologize to the CBBC and all the breed associations and look forward to better communications in the future. Feedback from the associations would be appreciated as soon as possible because as you know the new bull evaluation forms are already in use. If you or any of the breed associations have further questions or concerns then please feel free to contact me. Kind regards, Murray Jelinski DVM, MSc Secretary‐Treasurer, WCABP