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Effect Of Castration On Plasma Luteinizing Hormone Concentrations In Prepubertal Boars, R. J. Kittock, J. E. Kinder, R. K. Johnson
Effect Of Castration On Plasma Luteinizing Hormone Concentrations In Prepubertal Boars, R. J. Kittock, J. E. Kinder, R. K. Johnson
Department of Animal Science: Faculty Publications
Mean concentrations and the occurrence of pulsatile release of luteinizing hormone (LH) were determined in 14-wk-old crossbred boars (50.5 ± 1.5 kg) after bilateral or unilateral castration at 10 wk of age. Blood was collected at 10-min intervals for 5 h. Then gonadotropin releasing hormone (GnRH; 40 / μg) was given and sampling was continued at 5-min intervals for 1 h. Compared with intact boars, bilateral castration increased (P<.001) mean LH (982 ± 56 vs 389 ± 56 pg/ml), pulsatile releases of LH (7.0 ± .6 vs 2.0 ± .6 pulses/5 h) and LH pulse amplitude (617 ± 29 vs 360 ± 58 pg/ml). Unilaterally castrated boars did not differ from intact boars in any of the above measures of LH secretion. Testis weight increased more between 10 and 14 wk of age in the unilateral castrates than in the intact boars (432 ± 42 vs 245 ± 34%; P<.05). Thus, compensatory hypertrophy occurred within 4 wk of castration. Plasma testosterone was lower for bilateral castrates than for intact animals (.1 ± .8 vs 3.6 ± .9 ng/ml; P<.05) while unilateral castrates (3.8 -+ 1.0 ng/ml) and intact boars did not differ. Plasma estradiol concentrations in bilateral and unilateral castrates were not different from levels found in intact boars (1.8 ± 1.8, 8.8 ± 2.1 and 6.0 ± 1.8 pg/ml, respectively). While mean LH after GnRH was higher in bilateral and unilateral castrates than in intact boars (2,588 ± 147 and 2,693 ± 164 vs 1,928 ± 147 pg/ml; P<.01), castration did not affect the highest LH level after GnRH, time of highest level, magnitude of LH change or rate of LH response during the first 15 rain after GnRH. The rate of change of LH from 0 min to time of maximum LH of the bilateral castrates tended to be greater than that in intact boars (b=202 vs 94; P<.10). These data indicate that the negative feedback of gonadal steroids affects LH secretion.
Relationships Among Measures Of Testicular Development And Endocrine Function In Boars, A. P. Schinckel, R. K. Johnson, R. J. Kittock
Relationships Among Measures Of Testicular Development And Endocrine Function In Boars, A. P. Schinckel, R. K. Johnson, R. J. Kittock
Department of Animal Science: Faculty Publications
Nine blood samples were taken at 30-min intervals from 36 Landrace x Large White boars at each of eight ages (42, 56, 70, 84, 98, 112, 126 and 140 d). Serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T) and estradiol- 17β (E-2) were quantified by radioimmunoassay procedures. The maximum concentration of LH and the age at maximum concentration were predicted for each boar. Variability of LH samples was described for each boar by the pooled within age variance among LH samples and by the number of LH peaks. Measurements of testicular development taken at 140 …
Testicular Development And Endocrine Characteristics Of Boars Selected For Either High Or Low Testis Size , A. P. Schinckel, R. K. Johnson, R. J. Kittock
Testicular Development And Endocrine Characteristics Of Boars Selected For Either High Or Low Testis Size , A. P. Schinckel, R. K. Johnson, R. J. Kittock
Department of Animal Science: Faculty Publications
Thirty-six Landrace x Large White cross boars were selected from litters with either high or low estimated breeding values for 150-d paired testis weight. Blood samples were taken via jugular venipuncture at eight ages (42, 56, 70, 84, 98, 112, 126 and 140 d). At each sampling age, nine blood samples were taken at 30-min intervals. Luteinizing hormone (LH) was determined on the individual serum samples. Serum samples from each boar at each age were pooled and concentrations of follicle-stimulating hormone (FSH), estradiol-17β (E2) and testosterone (T) were determined. Paired testis width, testis length and body weight were …