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Summary. Behaviour in pigs is sexually dimorphic as early as 1 month of age; mounting of penmates is observed more frequently for males than for females. This mounting reaches its highest frequency during the 2nd month of life and then declines to a low frequency in prepubertal pigs. During the prepubertal period (3-5 months of age), bipotentiality of sexual behaviour is apparent in boars because they will not only mount oestrous females but they are also...

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bp0001redr4 | (1) | REDR1980

Control of seasonal reproduction in sheep and goats by light and hormones

Thimonier J

Summary. Seasonal variations of reproductive ability have been demonstrated in male and female sheep and goats. For the female, there is a distinct breeding season. Whilst there are large breed differences in the duration of the sexual season, oestrous cycles generally start when daylength is decreasing and end when daylength is increasing. In some breeds, ovulation without oestrus occurs during the non-breeding season. Although males are able to mate all the ...

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bp0001redr19 | (1) | REDR1980

Control of luteal function during early pregnancy in sheep

Martal J

Summary. Prolactin and LH are required for the maintenance of normal luteal structures during early pregnancy in the ewe, whilst luteolysis, induced by prostaglandin F-2α is inhibited by the presence of the conceptus. The trophoblast also secretes a local anti-luteolytic factor, trophoblastin, which is most probably a protein because it is thermolabile and inactivated by pronase. It is soluble at pH 9.6 and can be separated on Ultrogel. Trophoblastin is p...

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bp0003rdr15 | Development of the Reproductive Axis | REDR1994

Development of the gonadotrophic and somatotrophic axes of sheep

Polkowska J

The hypothalamo–pituitary–gonadotrophic axis develops in the sheep fetus from midgestation to late gestation. The GnRH neuronal centres seem to be fully developed in the fetus and their localization complies with the adult pattern. Pituitary gonadotrophs are responsive to exogenous GnRH and release LH and FSH in a pulsatile fashion; the highest concentrations in plasma are found during late gestation. In sheep, maturational changes of this axis continue through to ...

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bp0009rdr4 | (1) | REDR1986

Regulation of the secretion of FSH in domestic ruminants

Findlay J. K. , Clarke I. J.

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bp0009rdr12 | (1) | REDR1986

In-vitro fertilization of ruminants

First N. L. , Parrish J. J.

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bp0008rdr1 | Phylogenetics | REDR2014

Ruminant phylogenetics: A reproductive biological perspective

Silvia William J.

Summary. Phylogenetics is the study of evolutionary relationships among species. Phylogenies are based on the comparison of large numbers of characteristics among species. Traditionally, the field of phylogenetics was dominated by paleontologists so the characteristics studied were structural, often skeletal. The field of phylogenetics was revolutionized in the 1980s as scientists began using molecular data, first amino acid, then nucleotide sequences. This le...

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bp0009rdr1 | (1) | REDR1986

Control of GnRH secretion

Clarke I. J.

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bp0009rdr16 | (1) | REDR1986

Short light cycles induce persistent reproductive activity in Ile-de-France rams

Pelletier J. , Almeida G.

Summary. European breeds of rams appear to be responsive to photoperiodic changes even though there are large differences between breeds in the timing and amplitude of endocrine (LH and testosterone) and gametogenetic variations before the sexual season. Light regimens such as 6-month light cycles or alternations of constant short and long days every 12–16 weeks are able to entrain the parameters of sexual activity. In these regimens in which the period ...

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bp0013cpr5 | Nutrition-Metabolism-Reproduction Interactions | CPR1989