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Growth Of Testes And Testicular Morphology After Eight Generations Of Selection For Increased Predicted Weight Of Testes At 150 Days Of Age In Boars, R. R. Harder, D. D. Lunstra, R. K. Johnson, Roman L. Hruska
Growth Of Testes And Testicular Morphology After Eight Generations Of Selection For Increased Predicted Weight Of Testes At 150 Days Of Age In Boars, R. R. Harder, D. D. Lunstra, R. K. Johnson, Roman L. Hruska
Department of Animal Science: Faculty Publications
Weights of testes and epididymides, body weight, and morphometric measurements of testicular tissue of 75 boars of a line selected for eight generations for predicted weight of testes at 150 d of age and 75 boars of a randomly selected control line were used to evaluate the effects of selection on testicular development at 70, 100, 130, 160, and 450 d of age (n = 15 boars per line per age). Body weights for boars of the select and control line did not differ (P <.05) and the shape of the body growth curve was similar for both lines. Boars of the select line had larger testes than control boars at each age (P < .05), but there was a significant line x age interaction. The percentage increase of the select line mean over the control mean for weight of testes was 37% at 70 d, a maximum of 120% at 100 d, and 25% at 450 d. The percentage of the testes made up of seminiferous tubules differed between lines (P <.01). Lines had similar means of approximately 28% at 70 d and 71% at 450 d, but the mean for the select line was larger between 100 and 160 d of age; the greatest difference was 11.6% (control = 43.7, select = 55.3%) at 100 d. After 70 d of age, select-line boars had a greater percentage of seminiferous tubules with lumens that contained elongated spermatids (P <.lo). The proportion of the testes occupied by Leydig cells was greatest at 70 d, declined sharply between 70 and 130 d with a sharper decline in select-line boars, and then declined more gradually from 130 to 450 d of age. We conclude that selection for weight of testes at 150 d resulted in lower age at puberty for boars of the select line.
Growth Of Testes And Testicular Morphology After Eight Generations Of Selection For Increased Predicted Weight Of Testes At 150 Days Of Age In Boars, R. R. Harder, D. D. Lunstra, R. K. Johnson, Roman L. Hruska
Growth Of Testes And Testicular Morphology After Eight Generations Of Selection For Increased Predicted Weight Of Testes At 150 Days Of Age In Boars, R. R. Harder, D. D. Lunstra, R. K. Johnson, Roman L. Hruska
Department of Animal Science: Faculty Publications
Weights of testes and epididymides, body weight, and morphometric measurements of testicular tissue of 75 boars of a line selected for eight generations for predicted weight of testes at 150 d of age and 75 boars of a randomly selected control line were used to evaluate the effects of selection on testicular development at 70, 100, 130, 160, and 450 d of age (n = 15 boars per line per age). Body weights for boars of the select and control line did not differ (P <.05) and the shape of the body growth curve was similar for both lines. Boars of the select line had larger testes than control boars at each age (P < .05), but there was a significant line x age interaction. The percentage increase of the select line mean over the control mean for weight of testes was 37% at 70 d, a maximum of 120% at 100 d, and 25% at 450 d. The percentage of the testes made up of seminiferous tubules differed between lines (P <.01). Lines had similar means of approximately 28% at 70 d and 71% at 450 d, but the mean for the select line was larger between 100 and 160 d of age; the greatest difference was 11.6% (control = 43.7, select = 55.3%) at 100 d. After 70 d of age, select-line boars had a greater percentage of seminiferous tubules with lumens that contained elongated spermatids (P <.l0). The proportion of the testes occupied by Leydig cells was greatest at 70 d, declined sharply between 70 and 130 d with a sharper decline in select-line boars, and then declined more gradually from 130 to 450 d of age. We conclude that selection for weight of testes at 150 d resulted in lower age at puberty for boars of the select line.
Sperm Production In Boars After Nine Generations Of Selection For Increased Weight Of Testis, Thomas A. Rathje, R. K. Johnson, D. D. Lunstra
Sperm Production In Boars After Nine Generations Of Selection For Increased Weight Of Testis, Thomas A. Rathje, R. K. Johnson, D. D. Lunstra
Department of Animal Science: Faculty Publications
Body, testis, and epididymis weights were recorded and homogenization-resistant sperm nuclei were counted to determine daily sperm production and the number of sperm stored within the cauda epididymis (CAUDASP) in 145 boars of a control line (C) and 128 boars of a line selected for increased predicted weight of testis (TS) at 150 d of age. Random samples of boars were evaluated at five ages between 70 and 450 d in Generation 8 and 15 ages between 70 and 296 d in Generation 9. Data were analyzed using an animal model that included the fixed effect of line and the …
Uterine Mass And Uterine Blood Volume In Mice Selected 21 Generations For Alternative Criteria To Increase Litter Size, Merlyn K. Nielsen, R. J. Kittok, Y. L. Kochera Kirby
Uterine Mass And Uterine Blood Volume In Mice Selected 21 Generations For Alternative Criteria To Increase Litter Size, Merlyn K. Nielsen, R. J. Kittok, Y. L. Kochera Kirby
Department of Animal Science: Faculty Publications
Lines of mice, selected for 21 generations using alternative criteria to increase litter size, were evaluated for uterine mass and uterine blood volume to help explain differences in uterine capacity. For this study, mice were sampled from Generation 27, the sixth generation after relaxation of selection. Mice came from all four criteria of selection (LS = selection on number born to unaltered females; M = selection on an index of ovulation rate and ova success; UT = selection on uterine capacity; and LC = unselected control) in each of three replicates (a total of 12 lines). Measurement was at one …
Differences In Pup Birth Weight, Pup Variability Within Litters, And Dam Weight Of Mice Selected For Alternative Criteria To Increase Litter Size, M. A. J/ Van Engelen, Merlyn K. Nielsen, E. L. De A. Ribeiro
Differences In Pup Birth Weight, Pup Variability Within Litters, And Dam Weight Of Mice Selected For Alternative Criteria To Increase Litter Size, M. A. J/ Van Engelen, Merlyn K. Nielsen, E. L. De A. Ribeiro
Department of Animal Science: Faculty Publications
Selection for litter size had been practiced for 21 generations and relaxed selection for 13 generations in mice. Three replicates were used with four selection criteria: index of components (ovulation rate and ova success), uterine capacity, litter size, and an unselected control. Especially with selection for litter size and the index relative to the control, number of pups born had increased, and differences also occurred in mating weight. Dams of the three replicates and their litters were used to evaluate the effects of accumulated selection on pup birth weight, variability in weight of littermates, and dam's weight at mating and …