He said an underfed ewe will take condition off her back. The loss of 7kg body weight was a proxy measure for a reduction of one condition score. For a ewe with a body condition score of 3.5, a reduction of one will mean lambs 3kg lighter at weaning and a higher ewe death rate.
The Beef + Lamb New Zealand field day was designed to help farmers grappling with drought. It was held on Blair and Jane Smith’s farm near Five Forks, south of Oamaru and ironically in rain.
Stevens said for a flock lambing at 140% the cost of a reduction of one condition score was at least $1300 per 100 ewes, made up of 10 fewer lambs born and others that were smaller.
A 50kg ewe required 1kg of drymatter a day of feed to maintain her weight and high-performing flocks, 1.2kg drymatter a day. A 500kg beef cow may need 8kg drymatter a day for body weight maintenance.
In the lead-up to mating, ewes can be fooled in to thinking they are in better condition by having protein introduced for five to 10 days before the ram going out.
“You can introduce grain in to the system to make the ewe thinks she has been better fed and make her ovulate better than she would have otherwise,” he said.
Stevens suggested feeding rape seed meal or white lupin seed. Before lambing, extra high-energy supplements can boost ewes, especially those carrying twins or triplets.
Brassicas were generally too low in protein to be fed in the month leading up to lambing while poor quality hay and straw should be avoided at mating and in the four weeks before lambing. Limited silage and balage can be used before lambing but Stevens stressed they need to be supplemented with grain.
Blair Smith told the field day his biggest challenge was getting ewes ready for tupping but Agriseeds pasture systems manager Graham Kerr warned not to graze paddocks too soon after rain or plants could be damaged.
Kerr urged farmers to ensure ryegrass tillers were fully developed and were showing three leaves before grazing while the extra time would also allow clover to recover and feed quality to be higher.
Undersowing, using a direct drill without herbicide to seed a paddock that has been sacrificed because of drought, was an option to generate feed for winter and spring but it came with a risk.
“I would suggest that half the seed that is undersown is a waste of time but the rest works well. It fails because of competition from dead-looking plants. They are not dead and have roots ready to grow when it rains and crowd out the newly sown seed.”
Undersowing worked well on bare land or paddocks that had plenty of bare land after drought.
Kerr suggested farmers attach a small seed box to the front of a direct drill and drop a ryegrass and clover mix in front of the cultivars, which will also push the seed in to the ground. This would help crowd out weeds.
Options for late winter or early spring feeding include rape which could yield four to six tonnes a hectare, leafy turnips such as Hunter which can mature in 50-60 days, cereals such as oats or triticale or an annual ryegrass such as Agriseeds’ Hogan, which produces less than rape or cereals in winter but will still be producing in October.
