11 August 1995

Sheep respond to wheat-based diet

WINTER silage-based rations for pregnant ewes are now accepted practice on many farms but the costs continue to escalate.

The trend, coupled with the ban on straw burning and the possibility of cheaper cereal prices in the years ahead, prompted ADAS Drayton, Warwicks, to compare ewe and lamb performance on silage and wheat-based diets.

About 260 Bluefaced Leicester x Swaledale Mule ewes were selected from the Drayton breeding flock at the winter housing stage. Ewes were offered a silage or wheat-based ration. Those on silage had ad-lib access, also 0.02kg/head/day of a mineral supplement.

Supplement stopped

For the last two weeks before lambing this supplement was stopped and ewes were offered 0.45kg/head/day of a proprietary compound in two equal am and pm amounts.

In all three seasons the silage quality was good with ME values of from 11.1 to 11.5 MJ/kg dry matter and ammonia nitrogen levels between 7 and 11% of total nitrogen.

The wheat ration comprised untreated winter wheat straw supplemented with whole wheat grain, soyabean meal and minerals, offered at the rate of 0.59; 0.2 and 0.02kg a head a day respectively. This supplement was offered at a flat rate throughout the housing period in two equal am and pm feeds.

The straw allowance was 1.7kg/head/day to permit selection but avoid the wastage which can occur when straw is offered ad-lib. Ewe weight and condition were measured at housing and after lambing with the lambs weighed at birth, about six weeks, weaning and slaughter.

After lambing, ewes on the wheat ration were lighter and in poorer condition and the difference persisted to the weaning stage. But by ram introduction the following October, ewe liveweight and condition were similar for both winter ration treatments. Litter size and weight, based on the number and weight of lambs born alive and dead were similar for both treatments.

Lambs born alive

Performance details for lambs born alive only are shown in the table. Those from ewes on the wheat ration were heavier at six weeks, had higher liveweight gains to six weeks weaning and slaughter and were selected for slaughter earlier.

It was concluded that feeding pregnant housed ewes on a wheat-based ration is unlikely to depress ewe lambing performance and subsequent lamb performance.

The caution was added that, compared with ewes housed on an ad-lib silage diet, those that are on a wheat-based ration should be in adequate condition at housing, to cushion them against increased loss of weight and condition over the housing to post-lambing period.


Effect of ewe ration on lamb weight and liveweight gain

Ration

SilageWheat

Number of lambs788771

Lamb weight (kg)

Birth4.944.90

Six weeks21.121.7

Weaning34.334.7

Slaughter39.839.7

Daily liveweight gain (g)

Birth to six weeks330343

Birth to weaning312320

Birth to slaughter285296

Days to sale132128