Dry season drives sheep feed concern

The workshop with acknowledged sheep nutrition expert John Milton was organised by Brookton Farmarama, Primaries of WA and CRT on Thursday and promoted only by word of mouth to clients.

It attracted 83 farmers from as far away as Carnamah and Gnowangerup.

Dr Milton retired recently as a research associate professor at The University of Western Australia after 25 years but remains an honorary research fellow of its Institute of Agriculture and runs a feed analysis and consultancy company.

He said WA sheep farmers faced a critical time.

"Seasons like this are tough, some tough decisions have to be made," Dr Milton said.

"Feed was there this year so conception rates were high.

"Our ewes have lot of twins on board with all that good summer rain when we were joining, so that set them up.

"We got the early break; probably a bit early; but we didn't get the follow on, so now is right where the game is going to be made or lost."

Feeding regimes which aimed to maintain a condition score three during pregnancy and up to at least a "realistic" condition score two during lactation were critical to avoid hunger stress, maintain ewe health and for good birth weight which was "key" to lamb survival, Dr Milton said.

Visual assessment was not enough to gauge condition because wool often masked a drop off in condition.

"Learn to condition score your animals, the tools are on your hands (fingers), you don't have to go and buy scales,'' he said.

"Put your hands on the short ribs and feel for the fat and muscle.

"If there is no fat and the muscle is starting to be mobilised, they are short on feed."

Ewes should have been scanned not only to establish whether they have a lamb, but whether they are carrying twins, he said, and ewes with twins should be in a separate mob because of their higher nutritional requirements pre and post natal.

"You don't want to waste money putting too much extra feed into the singles - they're pretty tough anyway and if you do they'll produce big lambs - put the extra feed into the twinners.

"Feed them a nutritionally complete diet to supply energy, protein, minerals and vitamins, plus roughage."

"Off specification" grains, hays, straws and silages were a good base and straw or hay from drought crops or last year's frosted crops provided good value because nutrition had not gone into head development and was retained in leaf matter.

But cut height was critical.

"You want flag (leaf), not stem," Dr Milton said.

Supplementary grain feeding minimised the risk of toxaemia, often called twin-lamb disease, caused by low levels of glucose, he said.

While lupins do not have starch, are safe and provide high energy levels, Dr Milton advised they should not be in large quantity in the feed mix approaching lambing because they swelled in the rumen which was already constrained by the twin lambs carried.

For a similar reason, supplementary feeding was also needed with hay and straw.

"Hay is not enough if a ewe is carrying twins, she can't physically fit in enough hay and certainly not enough straw, to meet the nutrient requirements because she's got eight legs pushing on her rumen," he said.

"In the last part of pregnancy the fetus has a massive demand for glucose and if she's got twins on board the demand is doubled.

"She will start to mobilise fat to meet the demand if she has to.

"Grain is packed with energy and will give them all the glucose and nutrients they need.”

Booster vaccinations four weeks before lambing were also important to pass on immunity to the lambs.

"Ewes in low condition often don't elicit an immune response - their own immune system is being challenged, they're in poor condition and they've got twins on board, they're struggling and they won't have a strong immune response," Dr Milton said.

An additional ration of high quality feed was required in the final week before lambing to ensure onset of adequate runny colostrum production to feed the lambs after birth and, through suckling, helping strengthen the Merino’s mothering bond.

Dr Milton said barley was the best option, starting at least 10 days before lambing and building up to between 200 and 500 grams per head a day, depending on condition, in the week before lambing, and continuing after lambing.

“Ewes with twins often fail to produce sufficient colostrum,” Dr Milton said.

“In addition to the 12-14ME (metabolisable energy) pregnant ewes need daily, they also need an extra nutritional boost in the last week of pregnancy to lower progesterone levels in their blood.”

Dr Milton explained high levels of the hormone progesterone block production of colostrum.

The ewe’s liver had to first reduce the progesterone to a certain level before she began to produce and accumulate colostrum.

Twins generated higher progesterone levels than singles, so a twinner ewe’s progesterone level had further to fall to reach the point where production of runny colostrum could start, which was why an extra late-pregnancy nutrition boost from barley was beneficial for ewes carrying twins, Dr Milton said.

If signs of mastitis were detected, the amount of barley being fed should be reduced, he said.

It was also critical, he said, that essential mineral supplements were also fed because barley has no calcium to promote bone growth, no sodium and was low in sulphur.

Extensive studies have shown that in Australia up to 20 per cent of single Merino lambs and up to 60pc of twins could be lost within three days of birth.

Dr Milton said his own work and work by his students at the University of Western Australia with twinner ewes and cracked corn and barley as supplementary feeds had demonstrated significant improvement in lambing rates from additional feeding in the last week of pregnancy.

Continuing to provide extra feed after lambing was also critical to survival rates, he said.

But, if winter rains failed, there was the option of weaning lambs early.

"At six weeks or 12 kilograms they (lambs) will be chasing green because they aren't getting enough milk from mum and their rumen will be starting to develop,'' Dr Milton said.

"It's a tough call, but pull them off mum because they are probably only getting half the amount of milk they need from her.

"She's giving them companionship, worms and exercise - that's it, not much milk.”

Standing green crops, particularly oats, were extremely valuable as feed for ewes and lambs with the crop providing shelter for the lambs as well as feed, Dr Milton said.