Endocrine changes from birth to puberty in the heifer

in Reproduction

Summary. Twelve autumn-born Hereford × Friesian heifers were studied to characterize changes in the patterns of LH and FSH secretion occurring from birth through the peripubertal period. A once weekly blood sampling regimen, starting 3 days after birth, was combined with periods of frequent sampling (15-min intervals for 24 h) every month from 3 weeks of age.

Mean plasma LH concentrations decreased over the period from birth to 15 weeks of age, largely due to a decrease in basal LH concentrations. Thereafter, mean plasma LH concentrations increased to 39 weeks of age, mainly as a consequence of increasing LH episode frequency and LH episode amplitude.

Oestrus was detected using an oestradiol-treated steer, and ovulation inferred from progesterone profiles. A 'short luteal phase' oestrous cycle preceded the first observed oestrus, and this was followed in all heifers by a normal length luteal phase. However, no increase in mean LH concentrations, basal LH concentrations, LH episode frequency, LH episode amplitude or change in mean FSH concentration could be directly associated with the onset of puberty. It is therefore concluded that the gonadotrophic stimulus for first ovulation must occur abruptly.

Keywords: puberty; heifers; LH; FSH

If the inline PDF is not rendering correctly, you can download the PDF file here.

 

     An official journal of

    Society for Reproduction and Fertility

 

Sept 2018 onwards Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 120 28 5
PDF Downloads 709 318 23