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Type: Journal article
Title: Reproductive performance in the Sheep CRC Information Nucleus using artificial insemination across different sheep-production environments in southern Australia
Author: Geenty, K.
Brien, F.
Hinch, G.
Dobos, R.
Refshauge, G.
Mccaskill, M.
Ball, A.
Behrendt, R.
Gore, K.
Savage, D.
Harden, S.
Hocking-Edwards, J.
Hart, K.
van Der Werf, J.
Citation: Animal Production Science, 2014; 54(6):715-726
Publisher: CSIRO
Issue Date: 2014
ISSN: 1836-0939
Statement of
K. G. Geenty, F. D. Brien, G. N. Hinch, R. C. Dobos, G. Refshauge, M. McCaskill, A. J. Ball, R. Behrendt, K. P. Gore, D. B. Savage, S. Harden, J. E. Hocking-Edwards, K. Hart and J. H. J. van der Werf
Abstract: The present paper covers reproductive performance in an artificial-insemination (AI) program of the Sheep CRC Information Nucleus with 24 699 lambs born at eight locations in southern Australia across five lambings between 2007 and 2011. Results from AI with frozen semen compared well with industry standards for natural mating. Conception rates averaged 72%, and 1.45 lambs were born per ewe pregnant for Merino ewes and 1.67 for crossbreds. Lamb deaths averaged 21% for Merino ewes and 15% for crossbreds and 19%, 22% and 20% for lambs from ewes that were mated to terminal, Merino and maternal sire types, respectively. Net reproductive rates were 82% for Merino ewes and 102% for crossbreds. From 3198 necropsies across 4 years, dystocia and starvation-mismothering accounted for 72% of lamb deaths within 5 days of lambing. Major risk factors for lamb mortality were birth type (single, twin or higher order), birthweight and dam breed. Losses were higher for twin and triplet lambs than for singles and there was greater mortality at relatively lighter and heavier birthweights. We conclude that reproductive rate in this AI program compared favourably with natural mating. Lamb birthweight for optimum survival was in the 4–8-kg range. Crossbred ewes had greater reproductive efficiency than did Merinos.
Keywords: Causes of lamb mortality; lamb survival; sheep breeds
Rights: Journal compilation © CSIRO 2014
RMID: 0030016111
DOI: 10.1071/AN11323
Appears in Collections:Animal and Veterinary Sciences publications

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