The effects of restricted suckling and prepartum nutritional level
on reproductive performance of primiparous crossbred beef cows.
G.T. De Nava Silva, D.L. Burnham, M.F. McDonald, S.T. Morris.
Department of Animal Science, Massey University, Palmerston North,
New Zealand.
Proceedings of the New Zealand Society of Animal Production 1994,
54: 307-310
Reproductive performance was recorded in a total of 21 two-year-old
Hereford x Friesian and Simmental x Friesian primiparous cows before and
after restriction of calf suckling. Cows were allocated one of two pastures
allowances from day 112 to 212 of gestation so that the high nutrition (HN)
group gained 0.75 kg/d, and the low nutrition (LN) group gained 0.17 kg/d
during mid-gestation. Suckling was suppressed for 7 days by fitting nose plates
to 46-day-old calves in the restricted suckling (RS) group, whereas the normal
suckling (NS) group remained as a control. Dominant follicles in the ovaries
occurred in all cows by day 32 post partum and underwent a pattern of growth
and atresia before first ovulation. Restricted suckling cows had a shorter
interval from calving to conception than NS cows (76.0 ± 5 vs 94.1 ± 6 days,
P<0.05, whereas genotype and nutritional treatment had no effect on interval to
conception. However, the beneficial effect of suckling restriction on days from
calving to conception only occurred in cows fed the high herbage allowance in
mid-gestation. RS calves spent more time grazing during the period of
attachment of nose plates and differences in behaviour remained over a further
5 days after nose plates were removed (62.4 ± 7 vs 38.6 ± 7 minutes spent
grazing; P<0.001), but were lighter at weaning (146.7 ± 3 vs 162.4 ± 3 kg;
P<0.01). Despite the lower calf liveweight at weaning it is concluded that
manipulation of suckling through fitting nose plates to calves can be used to
initiate earlier re-breeding in primiparous cows.
Keywords: NZSAPAB;
Beef heifers; post-partum reproduction; suckling behaviour; nose
plates.
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Last Updated 25-01-1997
