Watch: worm resistance evident in Robertstown

Ricky Milligan farms 64ha at Robertstown, Co Kildare, in partnership with his father Henry. They run a spring-calving suckler herd, finishing male progeny as steers at 24 months, as well as a dairy calf-to-beef enterprise.

Ricky currently runs 40 cows, with a genetic base of Hereford crossed with Simmental and Limousin. A small number of his cows are first-cross from the dairy herd. The mature herd is at an average replacement index of €104 and quite well-balanced for both maternal and terminal traits.

Ricky has the heaviest average spring-calving cow in the programme at 735kg, but his calves’ 200-day weight is fourth highest at 294kg.

Dairy beef

Given the queries and responses on the dairy beef section of our Ploughing live demonstrations last week, these types of systems are becoming more and more popular across the country.

Indeed, many of our BETTER farmers have turned, or are turning toward dairy calf to beef enterprises in order to boost their output, having reached their own personal limits in terms of suckler cow numbers.

“They’re a cheap means of getting heads on the ground,” Ricky told me as we walked through a field of his sucklers, “the thing about these [sucklers] is, half of your stocking rate is not for sale.”

“Having said that, I don’t think that I’d go full dairy beef, I’m a believer in spreading the risk. This year we’ve bought in 39 Hereford-cross (Holstein/Montbeliarde) calves. They came in three batches – one of 18 and one of 12 early in the spring, and the last nine just before Good Friday. We get all of our calves from the same farm in Tipperary.”

Once breeding gets going in the suckler herd, the dairy calves run ahead of the cows and get the pick of the grass. I’ll keep them on just under 1kg of ration during the first grazing season.

“It’s only really in August that they’re developed enough to eat big volumes of grass,” Ricky said.

In terms of managing these calves, on arrival they immediately receive an electrolyte/vitamin mix and then 20ml of vecoxan within a few days. The latter measure is taken on veterinary advice after an outbreak of blood scour some years back.

Ricky feeds his calves 6l of milk replacer daily, split in two equal feeds at consistent times. Milk replacer is 24% crude protein and fed at a rate of 125g/l.

Dosing trial

Ricky recently partook in a dosing trial as part of Teagasc Walsh Fellow Researcher Anne Kelleher’s postgraduate studies. Anne is based at Grange and the aim of the trial was to investigate the prevalence of resistance to wormers across Irish drystock farms.

Two products were tested, ivermectin- (IV) and fenbendazole-based (FB). Calves were split into two for dosing, such that gender and faecal egg counts were similar for both groups.

The IV product was injected under the skin and the FB product was an oral drench. Dosing rates and weights were strictly adhered to.

Two weeks post-dosing, the IV calves showed a 78% kill according to faecal samples, while FB had achieved a 99% kill, indicating that there is some IV resistance on Ricky’s farm.

The IV calves actually grew faster in the fortnight post-dosing than the FB calves (ADG 1.13kg vs. 0.87kg), which is likely due to the more intense worm kill from FB causing slightly more stress to the calves.

One month post-dosing the benefits of the more-complete FB worm kill showed in a 0.24kg daily average daily gain response for the complete month post-treatment (1.41kg vs. 1.17kg).