Sperm production in boars after nine generations of selection for increased weight of testis.
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 linear, quadratic, and cubic effects of age. Variance components were estimated using a DFREML algorithm. Boars of the TS and C line did not differ in body weight (P > .05) in Generation 8. In Generation 9, boars of line TS were heavier between 118 and 198 d of age (P < .001); thereafter, body weights of the lines were similar (P > .05). The increase in organ weights for the testes and epididymides between 70 and 160 d of age were greater (P < .01) for boars of line TS in each generation, and differences between the lines in testis weights established around puberty were maintained at 450 d of age. Daily sperm production and CAUDASP increased more rapidly at younger ages and plateaued at greater values (P < .05) in boars of line TS. At ages less than 200 d, boars of line TS produced more sperm per gram of parenchyma than control boars.(ABSTRACT TRUNCATED AT 250 WORDS)
Rathje
T A
TA
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA.
Johnson
R K
RK
Lunstra
D D
DD
D000375:Aging / Q000502:physiology; D000465:Algorithms; D000818:Animals; D001835:Body Weight / Q000235:genetics / Q000502:physiology; D001947:Breeding; D002454:Cell Differentiation / Q000502:physiology; D004822:Epididymis / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology; D016014:Linear Models; D008297:Male; D008954:Models, Biological; D009929:Organ Size / Q000235:genetics / Q000502:physiology; D012641:Selection, Genetic; D012741:Sexual Maturation / Q000502:physiology; D013091:Spermatogenesis / Q000502:physiology*; D013094:Spermatozoa / Q000166:cytology; D013552:Swine / Q000235:genetics / Q000502:physiology*; D013737:Testis / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology*