More dries and triplets

Ewe scanners are detecting a surge in triplets this season, Joanna Grigg reports.

March-tupped mobs have some curve-bending conception results.

Lower North Island ewe pregnancy scanners, contacted by Country-Wide, have seen a trend for more dry (empty) ewes than average. At the same time, these mobs have more triplets and twins on board than usual.

Because of the high multiples, the end result is close to the district average. But there is the headache of more lambs being a triplet and the lost opportunity from 10% of ewes being dry.

These higher dry rates were seen in March-tupped mobs, across the lower North Island, upper south and parts of North Canterbury. High dry rates typically go hand in hand with fewer multiples, especially when driven by lower ewe body weight and a lack of flushing feed. This is not the case with more triplets and fewer singles than expected.

By all accounts, late summer feed quantities were very good and farmers enjoyed tupping feed surpluses. Hawke’s Bay had a cracker of a season following significant February rain. Perhaps here lies the answer. One suspect behind the higher dry rate is fungal toxins. This includes zearalenone, a naturally occurring mycotoxin from the Fusarium fungus. It grows on pasture, can interfere with oestrogen production and is proven to quickly have an affect on ewe ovulation. It sits on the dead material, so aged, rank pastures are more at risk. Ewe urine tests would have confirmed it. A change of feed type may have helped.

Carl Williams, AgScan, Feilding, witnessed this trend for March-tupped ewes across his scanning beat, through Gisborne, Port Waikato, Waipukurau, Dannevirke to Taihape.

He said there are some good results, such as 225%, but also high dry rates, more than 5%. Some mobs that were usually 4% dry, had 7% dry.

Those ewes that did ovulate, had higher multiple pregnancies than previous years. His thoughts were a touch of facial eczema and other fungal effects were at play.

“Barbers Pole, in flocks that hadn’t seen it before, might also have had an effect.”

Zearalenone doesn’t often rear its head. By the time farmers’ realise it could be an issue, it’s too late to test. Some of his clients were planning to use dry ewe sale proceeds to buy in-lamb ewes.

Andrew Vavasour, Ewe Scan, had been scanning his way across Gisborne and Wairoa. Most farmers were happy with the results. Many places had results starting with a two, he said, with one place scanning 226%.

“I’ve never seen a place have more triplet ewes than twinning ewes, but I saw it this year.”

This mob had 350 triplet ewes, 347 twins, 88 singles and 2.5% dry. At 44% of the mob with triplets, this was above the typical 30% to 40% triplet rate. One negative observed was poor first cycle conceptions.

“At one place there were zero ewes in the first cycle.”

“It’s going to be a drawn-out lambing.”

Vavasour suspects it was caused by some form of fungal toxin limiting early conception.

Some of his clients this year asked for foetal aging within 10 days. They plan to use this to manage ewe feeding and condition closely, down to the wire. Their options for managing these extra triplet-bearing ewes include set-stocking with the twins, or sprinkling them at light stocking rate through calving cows, he said.

By July there was plenty of quality “bright green” feed ahead of ewes and Vavasour said the tail of light ewes was very small. In past years, he’s seen 25% of mobs light but only 10% would be below desired condition this season, on average, he said.

James McKay, McKay Scanning Services, said his early Hawke’s Bay and Wairarapa flocks were showing 10% dry rates and a lot of late conceptions. These were in Romney-based mobs. The April-mated flocks were much improved, with flocks scanning around 175% and dry rates at 3%.

Zearalenone was not mentioned over tupping, but there has been talk about it since, he said.

“A wet and warm autumn also meant parasites may have been an issue.”

Facial eczema was seen in Hawke’s Bay and even into the Wairarapa, he said.

Because of the good season, more hoggets were joined with the ram. Recent cold wet weather has put some pressure on ewe condition, with a tail of light ewes being seen.

Nitrogen costs had meant farmers were deciding to quit some in-lamb ewes, like B flock ewes, rather than spend money on fertiliser to grow feed for them, he said.

“Some are selling up to 5% of the mob – no wonder the Feilding market did a bit of a dive last week.”

The ewe price fell from $220 to about $170, he said.

“Our discussion group discussed using nitrogen only strategically in spring – about 70kg on some areas, not all areas.”

Further south, February and March-tupped mobs were showing a lot of variation. Hamish Monteath, North Canterbury sheep scanner, mainly scans stud and EID flocks, after selling the main business. Within a district there were excellent results (low dry and high multiples), as well as some mobs with high dry rates.

“This was not related to tupping feed and could be fungal toxins,” Hamish said.

Banks Peninsula seems to be an exception. Dan Broughton, Dan Scan, said Banks Peninsula had a fantastic autumn, after droughts and floods hit the region hard. He said dry rates were mostly 1%-3%, with mobs making 180% scanning with 10% triplets. Many mobs are 15 percentage points up (155% to 170%) which was very welcome. Older ewes had been retained and mated, to build numbers, he said.

“It’s really cool to see a smile on farmers’ faces after a really hard time, especially those in the eastern bays.”

Coastal North Canterbury mobs of older ewes were full of lambs but not first cycle – it’s mainly second, he said.

Zearale-what?

Facial eczema is usually the pin-up problem fungus for ovulation. But maybe another fungus, zearalenone, has reared its head this tupping. It finds a welcome home in warm muggy conditions and likes aged pasture, with dead material. The lower North Island and top-of-the-south had an unseasonal 25 to 100mm of rain in February followed by muggy weather. Ryegrass staggers in calves, and red boots from walking through pastures coated with fungus, were characteristic of late summer 2022.

Jason Clark, Vetsone, Hastings, said it is very hard to prove zearalenone caused high dry rates but agrees that, as a potential ovulation suppressant, it has slipped off the radar for many farmers and vets this autumn.

“Perhaps it was in the mix.”

He has noticed a trend for high numbers of empty ewes in March-tupped mobs in the Hawke’s Bay.

“Farmers that have come to the clinic have quietly mentioned 10% dry.”

The overall number of lambs expected has been as good as or better however, due to more triplets.

Clark said facial eczema would have been having an effect in some regions and vets advise farmers to test blocks for spore numbers.

“If you see lambs with floppy ears, then more sheep will have subclinical effects.”

Late February, a Nutritech newsletter warned of mycotoxin effects on cow production. Mycotoxin binders are an option to mitigate the effects for cattle but not an option for large scale sheep flocks. High endophyte ryegrass may be another influence. Staggers can disrupt mating activity and reduce conception rates. Early embryo losses could also have contributed.

Pete Anderson, veterinarian consultant, said that the widespread nature of the high empty rate suggests it is weather related. He is investigating high dry rates in high country beef cattle, with a focus on weather events.

A review of zearalenone studies (Smith, Morris 2006) included findings from a 1994 survey, Garthwaite et al. (1994). The survey found zearalenone at toxic levels in autumn on pastures from Northland to Southland. Nine percent of over 6000 samples tested had zearalenone at high enough levels for ewe fertility to be depressed. Another 35% were from paddocks where flocks would be ‘at risk’.

The effect is a depression in lambing rate of about 5% for every one mg/day of zearalenone ingested in a short period (five to seven days) and about twice this for longer (20-day) periods of exposure.

The extent of the effect, and the duration, depends on the quantity of zearalenone ingested and the period of time during which it is ingested. A feeding period of as short as five days at a level of six mg/ewe/day significantly reduced ovulation rates. The effects of as little as one mg/ewe/day, for 20 days, still resulted in a 20% reduction in ovulation rate. This carried over for at least one cycle after zearalenone intake ceased. Prolonged exposure, for 20 to 40 days, resulted in the effects persisting for at least two cycles after exposure ceased.

Zearalenone should have the effect of reducing the incidence of multiples. The 2022 results don’t follow this pattern however, with more multiples. The excellent flushing feed could have set a high multiple potential.

The jury is still out and the focus should be on picking the warning signs prior to next tupping.

FEWER TRIPLETS EXPECTED SOUTH

By early July, scanning in Otago and Southland was kicking off. Early indications were that the 2022 Southern drought had knocked multiple rates, as expected, but it wasn’t to disaster levels.

Dan Broughton, Dan Scan, said his early mobs were back to 175% from the usual 180% for example. Some ewes in Balclutha were back and the farmer said it was a result of being tight for feed over tupping, he said.

Ewe condition score at scanning continued to be lower than average and feed tighter, he said.

“I won’t be asked to re-scan the dries.”

Middlemarch mobs were scanning better, with dry rates at 1%. Ewes were running through well and Dan cracked a new personal scanning record of 7180 ewes in eleven and a half hours. More farmers were asking for foetal aging of early and mids, as well as lates. Usually, 60% of mobs were called for lates only.

Rowan Farmer, Stock Scan, said being 73 years old means he only scans a few mobs, to help out. His Oamaru mobs were all 20% up, into the 180s. One mob in the Maniototo region was 30% back, with two-tooths dropping from 200% to 156%. Farmers were pretty happy as fewer triplets, he said. Feed was green but limited.

Jason Farmer, Farmer Scanning Services, had noticed a trend for early April-mated flocks in the south to be 13 to 15 percentage points back. It was at the start of the main scanning season, so results might change a little, he said.

At this stage, up to 30% of the ewes in a mob were scanning with a single lamb, when typically, it would be 15% to 20%, he said. Triplets are usually up to 12% of the flock but it was more common for only 5% of ewes to be carrying triplets.

“Triplet ewe numbers have been halved.”

As an example, a Gore flock was down 20 percentage points, even after supplementary feeding over tupping. Cracking 180% was unlikely, with figures more like 167%. This was not due to any marked increase in dry rates, rather more singles. Perhaps the extra North Island triplet-bearing ewes may find a home in Southland.