Breed Group Differences in Testicular Growth Patterns in Spring-Born Ram Lambs

Abstract

Three groups of spring-born ram lambs were used to assess breed group differences in testicular growth patterns through 5 mo of age. Group 1 included 20 3/4-Finnish Landrace (Finn), 1/4-Rambouillet rams and 31 1/8-Finn, 7/8-Rambouillet rams. Group 2 included 23 3/4-Finn, 1/4-Dorset rams and 19 1/8-Finn, 7/8-Dorset rams. Group 3 included 21 black-faced (BF) rams (six Hampshire and 15 Suffolk) and 46 whitefaced (WF) rams (nine Dorset, 20 Barbados Blackbelly X Dorset, 10 Finn X Dorset and six Dorset X Finn). Scrotal circumference (C) was measured at 19, 43, 72, 100, 128 and 153 d in Group 1; at 20, 48, 76, 93 and 153 d in Group 2 and at 40, 60, 81, 103, 124 and 158 d in Group 3. Breed group X age interaction was tested to assess breed group differences in testicular growth patterns, and logistic curves were used to describe increases in scrotal circumference with age. In Group 1, 3/4-Finn and 1/8-Finn rams were similar in estimated final scrotal circumference at 150 d of age (260 and 259 mm, respectively), but rapid testicular growth began earlier in 3/4-Finn rams. The estimated age at which the growth rate in scrotal circumference was maximum was 81 d for 3/4-Finn rams and 93 d for 1/8-Finn rams. No differences were observed in testicular growth in Group 2 rams. However, in Group 3, smaller WF rams matured more rapidly than larger BF rams. Growth in scrotal circumference was most rapid at 99 d in BF rams and 88 d in WF rams. Within WF rams, Barbados Blackbelly X Dorset and Finn X Dorset rams matured earlier than Dorsets. In all groups, the primary breed difference was associated with age differences during the period of rapid testicular growth.

Development of the endocrine reproductive axis in hair breed ram lambs

“…No differences were detected in SC development, albeit the greater BW in Pelibuey and crossbred lambs from wk 12, which disagree with previous studies, where differences in SC in developing ram lambs were explained based on differences in breed BW (36) . The small number of lambs per group might have accounted for not detecting significant differences among genotypes.…”

“…No se detectaron diferencias en el desarrollo de la CE, a pesar del mayor peso de los corderos Pelibuey y de los cruzados a partir de la semana 12; esto no concuerda con estudios anteriores, donde las diferencias en la CE durante el desarrollo de los corderos se explicaron basándose en los diferentes pesos de las razas (36) . El pequeño número de corderos por grupo pudo haber influido para no detectar diferencias significativas entre los genotipos.…”

Factors Affecting Scrotal Measurements and Weight of Ouled Djellal Rams in Eastern and South-Eastern Algeria

“…This confirms our results that reveal a highly significant increase in testicular measurements during the spring period (7th-8th-9th month) vs. summer (10th-11th-12th month). According to Notter et al [3], the estimation of scrotal circumference in both mature and immature rams is complicated by seasonal fluctuations in testicular size, suggesting that evaluations of this size are depending upon the season of measurement as well as the age of the ram. In the same case, breeding activity (libido), testicular size, testosterone levels and seminal characteristics varies significantly with season of year, and will being lowest during the summer and highest during the fall [22].…”

“…These must have superior reproductive trait to improve the genetic merit of a flock and to reduce the number of breeding males so as to increase flock fertility [2]. The level of testicular development in the ram lamb may be indicative of the rate of sexual development in female siblings and future daughters of that ram (Land and Carr, 1975 cited by [3]). Reproductive capacities of rams are directly or indirectly involved in the reproductive process, either during natural reproduction or by the production of semen used for artificial insemination.…”

Biometria e formas dos testículos em cordeiros da raça Santa Inês explorados em regime de manejo intensivo

“…Parâ-metros corporais, testiculares, seminais, comportamentais, hormonais e suas correlações têm sido avaliados quanto à capacidade reprodutiva potencial, com destaque para o perí-metro escrotal (Notter et al, 1985).…”