Effects of mid-pregnancy nutrition and shearing on ewe body
reserves and foetal growth
N.B. JOPSON, G.H. DAVIS, P.A. FARQUHAR AND W.E. BAIN
AgResearch, Invermay Agricultural Centre, Private Bag 50034,
Mosgiel
NZSAP 2002 Abstract No. 14
Proceedings of the New Zealand Society of Animal Production 62:
49-52
In an experiment replicated over three years, ewes were
individually fed concentrate diets containing two levels of protein (12
and 18%) at either maintenance or 1.5 x maintenance from days 35 to 74
of pregnancy, and then at an allowance of approximately 2.0
kgDM/head/day on pasture until parturition. Half of the ewes within each
treatment were shorn on day 74. Ewes were CT scanned to measure body
composition at days 35, 74, 115 and 140 of pregnancy. Neither protein
nor energy level fed during mid-pregnancy had any significant effects on
conceptus growth, birth weight or lamb skeletal measurements. Shearing
resulted in changes in ewe body composition as well as an increase of
0.36 kg (P<0.01) in lamb birth weights. Lambs from the shorn ewes
were 14 mm longer in length (P<0.05) but 8 mm shorter in height
(P<0.05) than those from unshorn ewes. Shorn ewes lost 1.3 kg more
body fat (P<0.001) than their unshorn contemporaries over the second
half of pregnancy. Unshorn ewes lost 0.74 kg of carcass lean over this
period, while the shorn ewes gained 0.22 kg (P<0.001). The results
show that ewes can be fed maintenance during mid-pregnancy if this
allows good quality feed reserves to be built up in front of them for
the third trimester. Mid-pregnancy shearing is likely to increase lamb
survival in multiple born lambs through higher birth weights.
Keywords: NZSAPAB;
sheep; energy; protein; birth weight; CT scanning
Last Updated 30/07/2002
