Lamb and ewe performance of East Friesian x Coopworths relative
to pure-bred Coopworths
N.B. Jopson, K.G. Dodds, K.J. Knowler, R. Wheeler and J.C.
McEwan
AgResearch, Invermay Agricultural Centre, Private Bag 50034,
Mosgiel
Proceedings of the New Zealand Society of Animal Production.
2000 60: 47-50
Purebred East Friesians (EF) sires were used in both the 1996
and 1998 matings (n=2 and 4, respectively) to generate 62 and 66 progeny
for the two years. These animals were compared with approximately 1000
COOP lambs in each year for growth, ultrasonic fat and muscle depths,
wool, dagginess, host resistance to internal parasites, and reproductive
performance. For the 1998 mating, one F1 sire and 24 F1 dams were mated
to COOP ewes and rams respectively to produce approximately 73 paternal
and 33 maternal backcross progeny. Twenty four EF cross ewes were mated
in each of the 1998 and 1999 birth years, and reproductive performance
recorded. On average, the EF cross progeny had a live weight advantage
(P<0.001) of 1.9 and 4.2 kg at weaning and 6 months of age,
respectively, compared to COOP. Ultrasonic eye muscle depth did not
differ between sire breeds (P>0.05) after adjustment for live weight,
but EF cross progeny had significantly lower C and GR measurements. EF
cross progeny had lower fleece weight at 12 months (-0.46kg; P<0.001)
than COOP. Average dag score differed between sire breeds with EF cross
having lower scores (0.4 verses 1.2) compared to COOP. Sire breed
differences in resistance to parasites were not significant. Analysis of
the limited EF backcross data indicated positive EF direct and maternal
effects for weaning weight, negative EF direct effects for dag scores,
and negative EF direct and maternal effects for fleece weight. EF cross
ewes performed significantly better (P<0.001) in lambs born per ewe
lambing than the purebred COOP for both 2-tooth (2.57 cf. 1.84) and
mixed-age (2.76 cf. 1.98) classes. The high lambing percentage in EF
cross ewes meant that more than 70% of mixed-age ewes had three or more
lambs per lambing, which could result in management difficulties. There
was significant overlap in the sire-breed ranges for all traits, meaning
selection of sire was more important than breed selection.
Keywords: NZSAPAB;
sheep; Coopworth; East Friesian; growth; reproduction
Last Updated 12-07-2000
