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

DOI PDF 被引用文献12件

書誌事項

公開日
1978-11-01
権利情報
  • https://academic.oup.com/pages/standard-publication-reuse-rights
DOI
  • 10.1530/jrf.0.0540447
公開者
Oxford University Press (OUP)

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<jats:p>Summary. Milk samples were collected twice weekly from 535 dairy cows between parturition and the re-establishment of pregnancy to monitor ovarian activity by measurement of milk progesterone levels by radioimmunoassay. The mean progesterone levels after fertile and non-fertile first inseminations were similar from 21 days before until 13 days after insemination, those in non-pregnant animals declined while those in pregnant animals continued to rise until Day 22. Progesterone profiles of 47 repeat breeder cows (i.e. receiving &gt;3 inseminations) demonstrated that a variety of patterns was associated with the poor conception rate.</jats:p> <jats:p>A study of the post-partum interval showed that cows resumed cycles by 24 ± 0·6 days after calving; the length of this interval varied significantly with the season of calving and non-significantly with the lactation number (i.e. age) of the cow, but was not related to yield. Of the 535 cows studied, 5·2% had not started to cycle within 50 days of calving and a further 5·2% resumed cycles which subsequently ceased. The progesterone profiles of acyclic cows indicated that after treatment with 0·5 mg LH-RH or a progesterone-releasing intravaginal device (PRID) for 14 days 75% of animals apparently ovulated but the calving to conception interval was not significantly altered compared with that of untreated control cows.</jats:p>

収録刊行物

  • Reproduction

    Reproduction 54 (2), 447-458, 1978-11-01

    Oxford University Press (OUP)

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