INFLUENCE OF SUPPLEMENTAL LIGHTING ON PUBERTAL DEVELOPMENT IN BOARS (GONADOTROPINS, GNRH, PITUITARY, TESTOSTERONE)
Abstract
To understand the accelerated effects of supplemental lighting on puberty of boars, intensive blood sampling (20 min for 6 h) and slaughter experiments were conducted from 2 to 8 months of age. Hormone parameters in blood, pituitary and hypothalamus as well as changes of the testis tissue were measured. A total of 102 crossbred boars (Hampshire x Duroc x Yorkshire) were reared under natural lighting (30 lux) or supplemental lighting (1000 lux) beginning at 4 weeks of age. Boars received supplemental lighting from 6 40-watt fluorescent bulbs between 0530 and 2030 h. Serum concentrations of LH, FSH and testosterone and LH secretory spikes were determined in boars from 75 to 215 days of age. Libido scores were evaluated from 122 to 220 days of age. Hypothalamic GnRH, pituitary LH, FSH and PRL, volume percentage of seminiferous tubules, tubular diameter and spermatozoa in testes were measured from 65 to 246 days of age. All parameters were found to be similar (P > .05) between natural and supplemental lighting treatments except serum LH and/or libido scores at younger ages. Mean serum concentrations of LH were greater (P < .05) in boars reared under supplemental lighting than boars reared under natural lighting at 75, 89, 103 and 131 days of age. Serum LH concentrations decreased as boars became older. At 122 days of age, libido scores of the supplemental-lighted boars tended to be higher (P = .10) than natural-lighted boars. These data suggest that supplemental lighting has some accelerated effects on the onset of puberty in boars at younger ages during prepubertal development.
Degree
Ph.D.
Subject Area
Anatomy & physiology|Animals
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