Analyse Des Variations Saisonnières De La Fertilité Des Bovins Dans Le Jura Français

Courot, M.; Goffaux, Marie-Julie; Ortavant, R.; Vuidepot, R.; Vuidepot, M.

doi:10.1051/rnd:19680203

Cited by 5 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Postpartum anoestrous periods were shortest during late spring and early summer and longest during fall and winter (Warnick, 1955;Thibault et al, 1966;Bulman & Lamming, 1978;Peters & Riley, 1982) and may be shortened in winter by exposure to long photoperiod . Conception rates were higher from fall to spring than from spring to fall (Thibault et al, 1966;Courot et al, 1968). Follicular growth was greater in winter and spring in comparison with fall as determined by a greater number of both normal and atretic follicles (Rajakowski, 1960).…”

Section: Introductionmentioning

confidence: 99%

Effect of photoperiod on LH, FSH and prolactin patterns in ovariectomized oestradiol-treated heifers

Critser¹,

Lindstrom²,

Hinshelwood³

et al. 1987

Reproduction

View full text Add to dashboard Cite

Angus and Angus crossbred heifers were ovariectomized, treated with oestradiol implants and randomly assigned to the natural photoperiod of fall to spring for 43 degrees N latitude or extra light simulating the photoperiod of spring to fall. Weekly blood samples were taken for 6 months (fall to spring equinox). All heifers were cannulated every 4 weeks and blood samples were taken for 4 h at 15-min intervals. Sera were assayed for LH, FSH, prolactin and oestradiol. In samples taken weekly, serum LH and FSH concentrations were higher while serum prolactin was lower in heifers exposed to natural photoperiod. There was a photoperiod X time interaction for both FSH and prolactin with concentrations diverging as photoperiod diverged. Circulating concentrations of oestradiol were not different between groups. In samples taken every 4 weeks at 15-min intervals, baseline concentrations of LH and FSH and LH pulse amplitude were higher while prolactin pulse frequency was lower in heifers exposed to natural photoperiod. There was a photoperiod X time interaction for each of these pulsatile characteristics. The correlation between LH and prolactin concentrations estimated from the 15-min samples differed between the two photoperiod treatment groups. The pooled correlation coefficient (r) was -0.12 under natural photoperiod and +0.50 under extra light. There was also a photoperiod X time interaction with negative correlations occurring when photoperiod was decreasing and positive correlations occurring when photoperiod was increasing. These results support the hypothesis that photoperiod alters serum concentrations of LH, FSH and prolactin in cattle.

show abstract