The effect on sheep reproduction of grazing willow fodder blocks during drought

D.W. PITTA, T.N. BARRY, N. LOPEZ-VILLALOBOS AND P.D. KEMP

Institute of Veterinary, Animal and Biomedical Sciences , Massey University, Private Bag 11-222, Palmerston North

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NZSAP 2004 Abstract No. 18 Proceedings of the New Zealand Society of Animal Production 64: 67-71

A trial was conducted in the summer/autumn of 2003 to determine the effect of grazing on willow fodder blocks (6,000 stems/ha) during mating, relative to control ewes grazed on drought pasture, upon ewe production and reproduction. Grazing occurred over 10 weeks, from 19 February including 3 cycles of mating, with ewes randomly assigned to four treatment groups each of 100. The treatments were short drought pasture (typical of drought pasture), long drought pasture (typical of the pasture growing in the willow fodder blocks), short drought pasture with restricted willow access (restricted access) and full access to willow fodder blocks (fenced on the willow all the time; full access). After mating the four groups were joined together and managed as one mob until weaning.

Substantial live weight loss occurred in the short control group (101 g/day), as would occur in severe drought conditions and reproductive rate was low. Ewes in the full access group had significantly (P<0.05) less live weight loss of 40g/day, with reproductive rate increased by approx 20% units (P<0.05). The increase in reproductive rate in the group with full access to willow fodder blocks was due to increases in fecundity, with more ewes giving birth to twin lambs. Live weight loss during mating in the long control and restricted access groups was intermediate between the short control and full access groups (75-86 g/d) and significantly different from either (P<0.05); reproductive rate was also intermediate between the short control and full access groups but was not significantly different from either (P>0.05). Grazing willow fodder blocks with full access during times of drought can be used to reduce the decline in reproductive rate, which occurs when ewes are mated on drought pastures.

Keywords: NZSAPAB; Drought feed; willow (Salix sp.); sheep reproduction; fodder blocks

Last Updated 8/07/2004