Linked Life Data

10972304

Source:http://linkedlifedata.com/resource/pubmed/id/10972304

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2000-9-21
pubmed:abstractText
In mediterranean environments, pastures are very poor during the autumn and consequently small ruminants, such as sheep, would have been losing body mass for many months so, during mating, gamete production would be depressed in both sexes. Effectively, the nutritive requirements for a photoperiod-driven, annual reproductive cycle are out of phase with seasonal changes in food availability. The problem could be overcome through more flexible timing of reproduction, perhaps explaining variations in seasonality between breeds that originate from differing latitudes. To study these concepts and the mechanisms involved, the endogenous rhythms and responses to photoperiod were compared in rams of 'mediterranean origin' (Merino) and 'temperate origin' (Suffolk). Groups of 16 rams of each breed were given a constant food supply and subjected to 16 months of constant equinoctial photoperiod (12L : 12D) or simulated 'mediterranean' changes in daylength (from 14L : 10D to 14D : 10L). With nutritional and photoperiodic inputs held constant, Merino and Suffolk rams showed similar endogenous rhythms in reproductive activity. Under constant nutritional inputs and a mediterranean photoperiodic cycle, the endogenous rhythms were modified differently in the two breeds, with the Merinos starting and finishing their seasons about 2 months earlier than the Suffolks. These observations partially explain the patterns observed in rams kept under field conditions. It is now necessary to test whether the rhythms of reproduction in these breeds are also modified by changes in nutrition and social cues.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1031-3613
pubmed:author
pubmed:issnType
Print
pubmed:volume
11
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
355-66
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Determinants of the annual pattern of reproduction in mature male merino and Suffolk sheep: modification of endogenous rhythms by photoperiod.
pubmed:affiliation
Faculty of Agriculture (Animal Science), The University of Western Australia, Nedlands, Australia. g.martin@agric.uwa.edu.au
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't