New Zealand Journal of Agricultural Research abstracts
Effect of weaning pre- or post-mating on performance of spring-mated ewes and their lambs in New Zealand
G. deNicolo
S. T. Morris*
P. R. Kenyon
Institute of Veterinary, Animal and Biomedical Sciences
Massey University
Private Bag 11 222
Palmerston North, New Zealand
P. C. H. Morel
Institute of Food, Nutrition and Human Health
Massey University
*Author for correspondence.
Abstract The objective of this experiment was to determine
the effect of lactation over the breeding period and early gestation on
ewe reproductive performance and liveweight. Romney ewes (n = 206)
with lambs at foot were allocated to either Early or Late weaning
groups, synchronised with CIDRs and joined with Suffolk rams 69 days
postpartum (P0). Lambs from the Early group were weaned at P0 while
lambs from the Late group were weaned at P21. The ovaries of each ewe
were observed laparascopically at P9. Late weaned lambs were
significantly heavier (P < 0.001)
at P21 and P47 than lambs in the Early group. There was no effect of
ewe treatment on ewe reproductive performance, liveweight over the
breeding period, number of corpora lutea present, pregnancy rates, or
on liveweight of the ewes at the subsequent lambing and lactation.
Birth and liveweights of subsequent lambs were not affected by the
treatment of the ewe over the breeding period. This research suggests
that the breeding of suckling ewes in an accelerated lamb production
system has no effect on ewe reproductive performance or on subsequent
lamb production.
Keywords weaning age; lamb growth; ewes; reproduction; accelerated lambing; mating; ovarian activity
A06007; Received 15 February 2006; accepted 3 May 2006; Online publication date 4 July 2006
New Zealand Journal of Agricultural Research, 2006, Vol. 49: 255–260
0028–8233/06/4903–255 © The Royal Society of New Zealand 2006
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