Puberty in Beef Heifers. III. Induction of Fertile Estrus

González-Padilla, Everardo; Ruíz, Roberto José; LeFever, D.G.; Denham, A. H.; Wiltbank, J. N.

doi:10.2527/jas1975.4061110x

Cited by 85 publications

(22 citation statements)

References 8 publications

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“…All of these situations have been artificially induced in the prepubertal heifer but none is followed by puberty (González-Padilla et al, 1975b;Barnes et al, 1980;McLeod et al, 1985;Skaggs et al, 1986). Puberty has been induced in heifers, close to the natural age of cyclicity, by simulating changes in oestradiol and progesterone normally seen at puberty in the heifer, although this treatment was ineffective in younger animals (González-Padilla et al, 1975c). It is therefore postulated that the central mechanisms controlling the cyclic release of gonadotrophins are not responsive to ovarian steroids until just before the onset of puberty.…”

Section: (A)mentioning

confidence: 99%

Endocrine changes from birth to puberty in the heifer

Dodson

McLeod²,

Haresign³

et al. 1988

Reproduction

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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.

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Section: (A)mentioning

confidence: 99%

Endocrine changes from birth to puberty in the heifer

Dodson

McLeod²,

Haresign³

et al. 1988

Reproduction

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“…Ovarian activity was identified as the first progesterone measurement >3 ng/ml which was followed by ovarian cycles. (Johnson & Ulberg, 1967; Gonzallez-Padilla, Wiltbank & Niswender, 1975) or LH-RH (Kittok, Britt & Convey, 1973, Bierschwal et al, 1975 Table 3. The interaction between season and the interval to the start of cyclicity was highly significant even after age had been taken into account.…”

Section: Studymentioning

confidence: 99%

Milk progesterone levels in relation to conception, repeat breeding and factors influencing acyclicity in dairy cows

Bulman¹,

Lamming²

1978

Reproduction

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122

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“…Short-lived corpora lutea also occur at puberty (González-Padilla et al, 1975;Berardinelli et al, 1979Berardinelli et al, , 1980 and at the beginning of the breeding season in ewes (Yuthasastrakosol et al, 1975). Several possibilities exist to explain regression of short-lived corpora lutea including: (1) inadequate gonadotrophic support; (2) inabi¬ lity of short-lived corpora lutea to respond to gonadotrophins; (3) premature release of luteolysin; and/or (4) an enhanced sensitivity of short-lived corpora lutea to the luteolytic signal.…”

Section: Introductionmentioning

confidence: 99%