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Titolo:
Declining fertility in dairy cattle: changes in traditional and endocrine parameters of fertility
Autore:
Royal, MD; Darwash, AO; Flint, APE; Webb, R; Woolliams, JA; Lamming, GE;
Indirizzi:
Univ Nottingham, Sch Biol Sci, Cattle Fertil Res Grp, Loughborough LE12 5RD, Leics, England Univ Nottingham Loughborough Leics England LE12 5RD 2 5RD, Leics, England Roslin Inst, Roslin EH25 9PS, Midlothian, Scotland Roslin Inst Roslin Midlothian Scotland EH25 9PS 9PS, Midlothian, Scotland
Titolo Testata:
ANIMAL SCIENCE
, volume: 70, anno: 2000,
parte:, 3
pagine: 487 - 501
SICI:
1357-7298(200006)70:<487:DFIDCC>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
POSTPARTUM OVARIAN ACTIVITY; MILK-YIELD; ENERGY-BALANCE; HOLSTEIN COWS; REPRODUCTIVE-PERFORMANCE; PROGESTERONE PROFILES; GENETIC-PARAMETERS; OVULATION; TRAITS; ESTRUS;
Keywords:
dairy cows; fertility; ovaries; progesterone;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
56
Recensione:
Indirizzi per estratti:
Indirizzo: Royal, MD Univ Nottingham, Sch Biol Sci, Cattle Fertil Res Grp, Sutton Bonington Campus, Loughborough LE12 5RD, Leics, England Univ Nottingham SuttonBonington Campus Loughborough Leics England LE12 5RD
Citazione:
M.D. Royal et al., "Declining fertility in dairy cattle: changes in traditional and endocrine parameters of fertility", ANIM SCI, 70, 2000, pp. 487-501

Abstract

Reproductive performance of 714 Holstein Friesian dairy cows was monitoredbetween October 1995 and June 1998 using thrice weekly milk progesterone determinations. Defined endocrine parameters such as interval to post-partumcommencement of luteal activity, inter-ovulatory interval and length of luteal and inter-luteal intervals were used with a number of traditional measures of reproductive performance to investigate the current status of fertility in a sample of United Kingdom dairy herds. A comparison of the resultsof the 1995 to 1998 trial with those of a previous (1975 to 1982) milk progesterone database, which included 2503 lactations in British Friesian cowsmonitored using a similar milk sampling protocol, revealed a decline infertility between these periods. Between 1975-1982 and 1995-1998, pregnancy rate to first service declined from 55.6% to 39.7% (P < 0.001), at a derived average rate approaching 1% per year This decline was associated with an increase (P < 0.001) in the proportion of animals with one or move atypical ovarian horn-lone patterns from 32% to 44%. There was a significant (P < 0.001) increase in the incidenceof delayed luteolysis during the first cycle post partum (delayed luteolysis type I; 7.3% to 18.2%) and during subsequent cycles (delayed luteolysis type II; 6.4% to 16.8%), although the incidence of prolonged anovulation post partum (delayed ovulation type I; 10.9% to 12.9%) and prolonged inter-luteal intervals (delayed ovulation type II; 12.9% to 10.6%) did not alter significantly. These changes resulted in an increase in mean luteal phase length from 12.9 (s.e. 0.09) to 14.8 (s.e. 0.17) days and an increase in inter-ovulatory interval from 20.2 (s.e. 0.1) to 22.3 (s.e. 0.2) days. The decline in fertility was also reflected in traditional measures of fertility since although interval to first service remained relatively unchanged (74.0 (s.e. 0.4) to 77.6 (s.e. 1.1) days) calving interval lengthened from 370 (s.e. 2.2) to 390 (s.e. 2.5) days. Collectively these changes may have contributed to the decline in pregnancy rates observed over the last 20 years.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/07/20 alle ore 01:40:22