A review of dystocia in sheep

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dc.citation.volume192
dc.contributor.authorJacobson C
dc.contributor.authorBruce M
dc.contributor.authorKenyon PR
dc.contributor.authorLockwood A
dc.contributor.authorMiller D
dc.contributor.authorRefshauge G
dc.contributor.authorMasters DG
dc.date.accessioned2024-01-16T20:58:10Z
dc.date.accessioned2024-07-25T06:33:43Z
dc.date.available2024-01-16T20:58:10Z
dc.date.available2024-07-25T06:33:43Z
dc.date.issued2020-11-01
dc.description.abstractThis review aims to describe the nutritional and non-nutritional factors that may affect parturition and dystocia in sheep. Dystocia is associated with fetopelvic disproportion, uterine inertia, failure of the cervix to fully dilate, malpresentation and disease or congenital defects in lambs. Dystocia can result in lambs that are born dead, or lambs that survive parturition but sustain birth injury including central nervous system damage. Dystocia risk is increased with high or low birthweight lambs, high (fat) or low liveweight ewes, and small first parity ewes. Other factors implicated include low muscle glycogen, pregnancy toxaemia, mineral imbalance causing hypocalcaemia, and a lack of antioxidant nutrients. Addressing these risks requires differential nutritional management for single and multiple bearing ewes. There is also evidence for stress and environmentally related dystocia. The stress related hormones cortisol, adrenaline and ACTH play a major role in the initiation and control of parturition in the sheep indicating a need for adequate supervision during lambing, provision of adequate feed and shelter at the lambing site, and small flock size to reduce physical and environmental stress. Hormonal control of parturition can be further disrupted by xenoestrogens or phytoestrogens in clovers and medics. Oestrogenic plants are still widely grown in mixed pastures but should be not be grazed by pregnant ewes. There is clearly a genetic component to dystocia. This is partly explained by incompatibility in physical size and dimensions of the ram, ewe and lamb. A rapid reduction in dystocia through direct genetic selection is problematic with low heritability of dystocia and some of its indicator traits such as lambing ease. This review provides broad interpretation of the literature, but conclusions are not definitive with widespread inconsistency in reported results. Further research is required to investigate dystocia under commercial production conditions, and this should be complemented by focussed studies under controlled conditions. Priorities include defining the fitness of the ewe to lamb, the role of stress and environment on parturition and the use of indicator traits to select for ease of birth.
dc.identifier.author-urlhttp://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000583630000016&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=c5bb3b2499afac691c2e3c1a83ef6fef
dc.identifier.citationJacobson C, Bruce M, Kenyon PR, Lockwood A, Miller D, Refshauge G, Masters DG. (2020). A review of dystocia in sheep. Small Ruminant Research. 192.
dc.identifier.doi10.1016/j.smallrumres.2020.106209
dc.identifier.eissn1879-0941
dc.identifier.elements-typejournal-article
dc.identifier.issn0921-4488
dc.identifier.numberARTN 106209
dc.identifier.urihttps://mro.massey.ac.nz/handle/10179/70423
dc.publisherElsevier B.V.
dc.relation.isPartOfSmall Ruminant Research
dc.subjectDifficult birth
dc.subjectLamb mortality
dc.subjectMerino
dc.subjectParturition
dc.subjectBreed
dc.subjectNutrition
dc.subjectPrevalence
dc.titleA review of dystocia in sheep
dc.typeJournal article
pubs.elements-id433972
pubs.organisational-groupOther
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