There is much less published literature on scrotal circumference in small ruminants compared to bovine bulls. However, in general the same principles seem to apply across species.
Producers should select rams or bucks that have the ability to settle a large portion of females early in the breeding season and sire offspring with the genetic potential for rapid, efficient growth. To help identify males that are capable, or not capable of settling females, producers can perform breeding soundness examinations.
The testicles and epididymis should be examined and palpated for their tone and size. Scrotal circumference is an important measurement taken during breeding soundness examinations of the buck or ram. This measurement is strongly related to the semen production capacity of the ram or buck. There is evidence that rams or bucks with large scrotal circumferences will produce more semen of greater viability. Also, female progeny from rams and bucks with larger scrotal circumferences will reach puberty earlier, have higher ovulation rates, and higher pregnancy rates than female progeny from males with smaller scrotal circumferences.
Scrotal circumference can vary by season and with body condition. It is larger during the fall breeding season (September to November), and can decrease 2 to 3 cm during the off- season. It is recommended that males that are used for breeding should have at least the minimum recommended scrotal circumference. The following recommended SC measurements pertain to males near to, or within breeding seasons.
Scrotal Circumference in Rams
| Classification | <14 months of age | >14 months of age |
| Excellent | >33cm | >35cm |
| Satisfactory | >30cm | >33cm |
| Questionable | <30cm | <33cm |
Minimum scrotal circumference in Rams
| Age (months) | Minimum Circumference (cm) |
| 5-6 | 29 |
| 6-8 | 30 |
| 8-10 | 31 |
| 10-12 | 32 |
| 12-18 | 33 |
| 18+ | 34 |
Scrotal Circumference in Bucks
The scrotal circumference in 45 kg dairy goats has been reported to be 25 to 28 cm with larger bucks having scrotal circumferences of 34 to 36 cm. Mature bucks (> 14 months old) should have a scrotum circumference of at least 25 cm.
No age or breed standards exist for scrotal circumference in meat goats, however, one evaluation of meat goats found that the scrotal circumference in 45 kg, seven month old Kiko and Boer bucks averaged 26 to 29 cm.
References
- Boundy, T. Routine ram examination. In Practice 14:219-228, 1992.
- Boundy, T. Collection and interpretation of ram semen under general practice conditions. In Practice 15:219-223, 1993.
- Pugh DG. Breeding soundness examination in male goats. Proc Seventh Ann Hudson-Walker/Vaughan Theriogenology Conference, Auburn University College of Veterinary Medicine; 1996. p. 29.
- Memon MA, Mickelsen WD, Goyal HO. Examination of the reproductive tract and evaluation of potential breeding soundness in the buck. In: Youngquist RS, Threllfall WR, editors. Current therapy in large animal theriogenology. 2nd edition. St. Luis: WB Saunders; 2007. p. 515-518.
- Mohbini S. Reproductive management in goats. Proc North Am Vet Conf, Vol. 14, Orlando, FL, 2000.