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New understanding of an old phenomenon: uncontrolled factors and misconceptions that cast a shadow over studies of the ‘male effect’ on reproduction in small ruminants

journal contribution
posted on 2014-01-01, 00:00 authored by Trina Jorre De St JorreTrina Jorre De St Jorre, P A R Hawken, G B Martin
In female sheep and goats, exposure to males can be used to induce ovulation and thus control and synchronise fertility. This ‘male effect’ offers simple, cost-effective, and hormone-free management of reproduction in flocks and herds but, despite decades of research, significant gaps in our knowledge impede commercial application. Many of these gaps can be traced back to misconceptions in the early documentation of the male effect, and others are the result of uncontrolled factors in experimental design. Consequently, it is often difficult to draw conclusions from past research, to further our understanding of the phenomenon, and to make recommendations
for industry application. Here, we describe 2 aspects of the male stimulus used to elicit the male effect that are often uncontrolled – the novelty of the stimulus males and factors that contribute to variability in the potency of the male stimulus. We discuss the physiology that underpins novelty, including the individual specificity of the sociosexual signals emitted by the male, and the concomitant ability of females to distinguish among individual males and remember them. Importantly, an understanding of the issue of novelty can make it easier to use the male effect in commercial practice. We also discuss difficulties in interpretation caused by variation in endpoints of the male effect (from neuroendocrine reaction to birth). We conclude that more rigour is needed in the control and reporting of male novelty, in pre experimentation separation of the sexes, and in extrapolation from detection of early responses to the male stimulus to reproductive outcomes.

History

Journal

Turkish journal of veterinary and animal sciences

Volume

38

Issue

6

Pagination

625 - 636

Publisher

Scientific and Technical Research Council of Turkey

Location

Ankara, Turkey

ISSN

1300-0128

eISSN

1303-6181

Language

turkish

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2014, TÜBİTAK