The effect of sward surface height on ingestive behaviour and
intake of once-bred and non-pregnant heifers under continuous stocking
management in early winter
P.R. Inwood, S.T. Morris, W.J. Parker, S.N. McCutcheon
Department of Animal Science, Massey University, Palmerston
North, New Zealand
Proceedings of the New Zealand Society of Animal Production.
1992, 52: 307-310
Ingestive behaviour and herbage intake were measured in 36
twenty-month old pregnant and non-pregnant Hereford x Friesian heifers
with an initial liveweight of 360 ± 21 kg (mean + SE). The heifers were
grazed under continuous stocking management on ryegrass (lolium
perenne)/white clover (Trifolium repens) pastures maintained
at a sward surface height of 7 cm or 11 cm. The groups of heifers (n =
6/group) were balanced for liveweight and pregnancy status and allocated
to three replicates per sward height. There were no significant
differences between the non-pregnant vs pregnant heifers in biting rate
(55 vs 57 bites/minute), total grazing time (573 vs 612 minutes/day),
ruminating time (319 vs 301 minutes/day) or idling time (546 vs 524
minutes/day). Nor did these parameters differ between sward heights.
Estimates of organic matter (OM) intake per bite derived from ingestive
behaviour parameters were not significantly different between the 11.0
cm and 7.0 cm pastures (0.23 vs 0.24 g OM/bite), but the heifers on the
11 cm sward had liveweight gains which were significantly (P<0.01)
greater than those of heifers on the 7 cm sward (1.10 kg/d vs 0.80
kg/d). There were no significant differences in liveweight gain between
pregnant and non-pregnant heifers. The results indicate that the target
liveweight gains for once-bred heifers of 0.8 kg/day during mid-
pregnancy can be achieved on ryegrass-white clover swards maintained at
a sward height of 7.0 cm. Liveweight gains of 0.8 kg/day during mid-
pregnancy will ensure once-bred heifers continue growing during
pregnancy to reach a calving target liveweight of 420 kg.
Keywords: NZSAPAB;
Once-bred heifers; pregnancy; sward height; grazing behaviour;
herbage intake; continuous stocking management.
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Last Updated 25-01-1997
