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Effect of selection for testosterone production on testicular morphology and daily sperm production in pigs

by Walker, Sara Elizabeth.

Abstract (Summary)
Walker, Sara Elizabeth. Effect of selection for testosterone production on testicular morphology and daily sperm production in pigs. (Dr. Joseph Cassady) The objective of this study was to determine effects of divergent selection for testosterone on testicular morphology and daily sperm production. Duroc boars from lines divergently selected for testosterone production in response to GnRH challenge for 10 generations followed by random selection were used. In generation 21 endogenous testosterone in the high testosterone line (H, n=54) and low testosterone line (L, n=44) averaged 490 ng/ml and 278 ng/ml (P < 0.01), respectively. Plasma FSH concentrations did not differ between lines (P < 0.3). Body weight, testicular weight, and epididymal weight were recorded for boars from H (n=82) and L (n=44) castrated at an average age of 211 d and 97 kg. Testicular tissues were sampled from animals castrated in generation 20 (H, n=46 and L, n=13). Volume densities for Leydig cells, seminiferous tubules, and Sertoli cells were estimated along with sperm production. After adjustment for body weight, average paired testicular weights for H and L were 417 g and 457 g (P < 0.01), respectively. Adjusted epididymal weights also differed between lines (P < 0.02), with H having larger epididymal weights. Line H (n=46) had greater volume densities of Leydig cells than L (n=13) (P < 0.02). Volume density of seminiferous tubules tended to differ between lines (P < 0.07), and Sertoli cell volume densities did not differ (P < 0.27). Sperm production traits, adjusted for age, did not significantly differ between lines. Selection for testosterone production in response to a GnRH challenge was an effective method of changing testosterone levels, testicular size, epididymal weight, and volume density of Leydig cells and seminiferous tubules. However, daily sperm production per gram of testes was unchanged. At this time, selection for testosterone in order to increase sperm production is not recommended. Effect of selection for testosterone production on testicular morphology and daily sperm production in pigs. by Sara Elizabeth Walker A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Master of Science Animal Science Raleigh 2003 Approved By: __________________________________ Dr. Charlotte Farin __________________________________ Dr. William Flowers __________________________________ Dr. Odis Robison __________________________________ Dr. Joseph Cassady Chair of Advisory Committee ii Personal Biography Sara Elizabeth Walker graduated from North Carolina State University in 2001 with a Bachelor of Science in Zoology and a minor in Genetics. She entered the Animal Science department in the fall of 2001 to begin a Master’s of Science degree in Animal Breeding and Genetics with an emphasis in reproductive physiology. She graduated with a Master’s degree from North Carolina State University in the spring of 2003. In the fall she will pursue a Ph.D. degree in Molecular & Cellular Pathology at Wake Forest University. iii
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School:North Carolina State University

School Location:USA - North Carolina

Source Type:Master's Thesis

Keywords:north carolina state university

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