Association of allelic variants of thyroid-binding globulin with puberty in boars and responses to hemicastration.

Hemicastration of males increases weight of remaining testis when conducted before Sertoli cells cease to proliferate. The current studies re-examined responses to hemicastration in one-quarter Meishan crossbred boars that differed for two alleles of thyroid-binding globulin (TBG). In the first experiment, boars at 25 days of age with either allele did not differ in degree of testicular development; however, at 56 days, boars with the C allele had more advanced testicular development than littermates with the A allele as evidenced by testes with seminiferous tubules of larger diameter (P<0.

Alteration of fertility endpoints in adult male F-344 rats by subchronic exposure to inhaled benzo(a)pyrene.

The objective of this study was to evaluate the reproductive risk associated with exposure of adult male Fisher-344 rats to inhaled benzo(a)pyrene (BaP). Rats were assigned randomly to a treatment or control group. Treatment consisted of sub-chronic exposure of rats via inhalation to 75microgBaP/m(3), 4h daily for 60 days, while control animals were unexposed (UNC).

Effects of benzo(a)pyrene on intra-testicular function in F-344 rats.

The objective of this study was to evaluate the reproductive risk associated with exposure of adult male Fisher-344 (F-344) rats to inhaled benzo(a)pyrene (BaP), a ubiquitous environmental toxicant present in cigarette smoke, automobile exhaust fumes and industrial emissions. Rats were assigned randomly to a treatment or control group. Treatment consisted of exposure of rats via nose-only inhalation to 75 microg BaP/m3, 4 hours daily for 60 days, while control animals were unexposed (UNC).

Growth and pubertal development of F1 bulls from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu sires.

The objective of the study was to characterize body growth, testicular development, and puberty from 8 to 14 mo of age in bulls (n = 120) produced by mating sires from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu breeds to MARC III ((1/4) Hereford, (1/4) Angus, (1/4) Red Poll, and (1/4) Pinzgauer) cows. Traits evaluated were birth weight, weaning weight (at 215 d), yearling weight, ADG from 8 to 14 mo of age, paired testicular volume growth from 8 to 14 mo of age, age at puberty (determined by production of 50 x 10(6) sperm with 10% motility), age at freezable semen (determined by production of 500 x 10(6) sperm with 50% motility), and, at 15 mo of age, paired testicular weight and daily sperm production per testis pair. There was an effect of sire breed (P = 0.

Genetic variation in sperm production.

In boars, the primary determinant of daily sperm production is the number of Sertoli cells, which establishes testicular weight. The only breed comparison of foetal testicular development in boars contrasted two diverse breeds, White composite (WC, Landrace-Yorkshire) with Meishan, a Chinese breed that undergoes pubertal development at a young age and has small testicular size. During the prenatal period, the pattern of change in testicular development is similar in these two breeds with both having their greatest proportion of proliferating Sertoli cells at 90 days of gestation, and with WC boars possessing more Sertoli cells and greater mass of seminiferous tubules during the latter half of gestation.