Resistant rams top performers


In Livestock5 Minutes

Initial results from a low input sheep progeny test indicate that offspring from rams bred for parasite resistance are also above average overall performers.

The test, LISPT is a three-year industry-funded project aimed at identifying the genetic footprint of the sheep which require minimal animal health intervention, are environmentally efficient but also highly productive, and profitable on a hill and high-country farm.

Included in an August 2020 update is an index merit overview based on 2020 lamb data from the low input progeny test flock. It shows that the top four overall performers, measured by the survival, growth, meat, FEC and dag sub-indexes, also ranked in the top six for parasite resistance, measured by the dual purpose internal parasite resistance index (DPF).

Of that top six, four were WormFEC Gold rams.

The news comes as no surprise to Allan Richardson, a member of the progeny test steering group. He is also chairman of WormFEC Gold, a ram breeding group selecting for genetic resistance to internal parasites and above average production performance.

Although the 2020 LISPT index merit summary is based on within-flock data only it vindicates the genetic selection pathway that the WormFEC Gold members have pursued.

“It’s something that all members have been focusing on for a long time, some as long as 30 years,” Richardson says.

The indicative results further proves that resistance to parasites is not at the expense of production and is one of the key messages that WormFEC Gold breeders are keen to get across to farmers. Another important message is how genetics can help stem the rise of drench resistance.

“It’s acknowledged across the sheep industry that drench resistance is a serious problem but there’s still not a great understanding among farmers of how to deal with it beyond a drench gun. We want to show how a packaged approach will help reduce the problem.”

The group is seeking funding for both a North and South Island trial on a farm with a drench resistance problem. The objective will be to show how the combination of genetics, management and targeted drenching can control the problem.

The benefits from using parasite-resistant rams accrue over the medium to long term, he says.

“The big thing is convincing farmers to make the change sooner rather than later, given that the obvious signs of a heavy worm burden and drench resistance become obvious only when the problem becomes serious.”

WormFEC Gold was formed in 2018 and has 15 breeders and 16 flocks throughout the country representing the main breeds. To be eligible members must have eight years of recorded data and the flock must be in the top 50% for maternal worth (NZMW) and parasite resistance (DPF) indices. Every year at least 30% of annual progeny must be recorded for parasite resistance and a range of productive traits.

An estimated 40% of New Zealand sheep farms could be battling resistance to triple combination drenches, according to sheep parasite management specialists Techion.

The prediction is based on analysis of faecal egg count reduction test data collected from 2005 until mid-year 2020.

In 2005 the resistance to combination drenches was low, but it’s become more common, even to triple combination products.

“Results show double combination drenches are failing on between 20% and 43% of farms, while triple combination drenches are failing on 15% of properties we have tested,” Techion chief executive Greg Mirams says.

While some would say Mirams has a vested interest in the problem he denies being alarmist.

“We’re drawing on a significant body of data collected over 15 years which proves that drench resistance is increasing rapidly.”

The problem is impacting animal welfare and performance, farm productivity and meat exports.

Validating the productivity effect, albeit with slightly dated information, is more Techion research from 2014-2017, funded by British supermarket chain Sainsbury’s. It estimates that the average NZ sheep farmer producing 5000 lambs potentially lost up to $75,000 annually due to reduced lamb weight gains from ineffective drenching practice.