Reproductive function in prepubertal lambs: ovulation, embryo development and ovarian steroidogenesis

Trounson, Alan; Willadsen, S. M.; Moor, R. M.

doi:10.1530/jrf.0.0490069

Cited by 23 publications

(13 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the study by Quirke & Hanrahan (1977), for example, the survival rate to term of 8-16-cell eggs from ewe lambs of the Galway breed after transfer to the uteri of adult ewes was less than half that of similar eggs from mature ewes (33 compared with 73%). Because of this and of the evidence of a different pattern of oestrogen secretion by lamb follicles in vitro and in vivo (Trounson, Willadsen & Moor, 1977;Quirke et al, 1981) it has been suggested ) that conditions in the developing follicle or in the reproductive tract between ovulation and the 8-16-cell stage may be related to the reduced fertility of very young ewes. A high frequency of errors of oogénesis or of fertilization, because of maternal age, could also be implicated and a karyotyping study, similar to that by Long & Williams (1980) with mature ewes, could provide useful clues in this direction.…”

Section: Discussionmentioning

confidence: 99%

Comparison of the survival of fertilized eggs from adult ewes in the uteri of adult ewes and ewe lambs

Quirke¹,

Hanrahan²

1983

Reproduction

View full text Add to dashboard Cite

Fertilized eggs, obtained from mature donor ewes, were transferred into the uteri of adult ewes and ewe lambs (1 or 2 eggs per recipient). The survival rate to term of the transferred eggs was similar in the two classes of recipients. The percentage of adult ewe and ewe lamb recipients which gave birth to twins was 45.3 and 41.1 respectively. Gestation length was shorter (P less than 0.01) and lamb birth weight lower (P less than 0.01) for ewe lamb recipients. The results indicate that the generally lower lambing rate of ewe lambs compared to adults is unlikely to be due to unfavourable uterine conditions.

show abstract

Section: Discussionmentioning

confidence: 99%

Comparison of the survival of fertilized eggs from adult ewes in the uteri of adult ewes and ewe lambs

Quirke¹,

Hanrahan²

1983

Reproduction

View full text Add to dashboard Cite

show abstract

“…The follicles are able to respond to exogenous gonadotrophins and ovulation may be induced (Mansour, 1959). If intrauterine insemination is used to bypass the cervical block, the eggs ovulated may be fertilized (Land & McGovern, 1968), and when transferred to adults at an appropriate stage of the oestrous cycle they develop normally (Trounson, Willadsen & Moor, 1977). The latter authors also demonstrated that the capacity of the lamb follicle to secrete oestrogen, testosterone and progesterone in vitro was similar to that of the adult.…”

Section: Genetic and Seasonal Variationmentioning

confidence: 97%

Reproduction in young sheep: some genetic and environmental sources of variation

Land¹

1978

Reproduction

View full text Add to dashboard Cite

Summary. 'The extent of genetic and environmental variation' in the development of reproduction in sheep is illustrated by examples with particular reference to variation among breeds and to the effects of photoperiod. The interactions between genetic and environmental effects are introduced ; these may be so great that genetic groups may reverse their ranking for rate of development in different environments. The 'physiology of puberty' is then discussed. The difficulty of separating puberty from seasonal variation is stressed, and a possible contrast is drawn between the physiological characteristics of genetic variation and those of environmental variation in reproductive development. Finally the physiological factors associated with sterility in young females are discussed; most studies, however, have been conducted during the time of year when adult females would also be expected to be sterile, so that conclusions are difficult and a 'missing link' cannot be identified.

show abstract

“…The reason for this embryonic loss has been suggested to be inadequate gonadotrophic support of the induced CL (Segal and Baker, 1973). Trounson et al (1977) claim that gonadotrophin production in the pre-pubertal sheep should be adequate. The abnormal dividing ova recovered in this experiment may indicate some inadequacy in the ova themselves or some inadequacy in the maternal environment.…”

Section: Yearmentioning

confidence: 99%

Reproduction in young female sheep induced to breed at various ages

Al-Wahab

Bryant

1978

Anim. Sci.

View full text Add to dashboard Cite

Two hundred and thirteen Suffolk x (Cadzow Improver x Scottish Blackface) young female sheep were mated either after the natural occurrence of puberty or at 140, 182 and 224 days of age in Year 1 and 140 and 182 days of age in Year 2 after treatment with progestagen (MAP) and 750 i.u. PMS; 90 to 100% of sheep ovulated after hormone treatment. Few sheep were found with embryos or live lambs in Year 1, possibly because of inadequacies in artificial insemination. In Year 2, after natural mating, the incidences of cleaved ova, live embryos 26 days after mating and live lambs born were 82, 33 and 23 % respectively for sheep mated at 140 days; 100, 31 and 23% respectively for sheep mated at 182 days; and 100, 62 and 31 % respectively for sheep mated after puberty. The occurrence of a second post-treatment ovulation in sheep without embryos at 26 days increased with age at treatment.

show abstract

Reproductive function in prepubertal lambs: ovulation, embryo development and ovarian steroidogenesis

Abstract: However, oestrogen production by lamb follicles immediately after explantation was higher than that of adult follicles and the administration of progesterone to lambs before PMSG treatment decreased subsequent follicular testosterone production.

Cited by 23 publications

References 15 publications

Comparison of the survival of fertilized eggs from adult ewes in the uteri of adult ewes and ewe lambs

Comparison of the survival of fertilized eggs from adult ewes in the uteri of adult ewes and ewe lambs

Reproduction in young sheep: some genetic and environmental sources of variation

Reproduction in young female sheep induced to breed at various ages

Contact Info

Product

Resources

About