Genetics and teamwork approach to calf management

Canterbury couple Warren Thomas and Nicole Mayberry are focused on getting the best from their young stock. They’ve spent three seasons refining their system to both maximise calf care and minimise non-replacements.

Inside Dairy

5 min read

Wood chip is Warren and Nicole’s preferred bedding material for the 14-bay rearing barn.

Westingdon Farm owner Warren and his partner Nicole are in a strong position to ensure all their calves are given a good start and positively contribute to the farm business. 

Having spent his early years building up equity and scale, Warren now has just the one farm to focus on. Admittedly, it’s a large farm, but its singularity prompts them to double down on policy and practice, ensuring they get the best out of their land, staff and herd.

Their calf-rearing policy focuses on a simple philosophy: to ensure all calves, whether replacements, those reared for beef, or bobbies, get to enjoy a healthy, well-cared for time on the farm. 

The couple also pay close attention to where their calves go when they leave the farm. That approach aligns well with the growing number of farmers wanting to explore options for non-replacement calves and ensure as many calves as possible are used in a meaningful way.

Better options with beef breeds 

With the 294ha farm under Synlait’s Lead with Pride programme, Warren and Nicole started considering how best to minimise the number of non-replacements to manage in the first place. 

“We opted to use sexed semen, which we put over the top one-third of the herd. Sexed semen does come at a cost, but as an investment, the genetic gain we get from it is significant,” says Warren. 

Last season, they went a step further, synchronising their 230 heifers to cycle and be mated with sexed semen. 

“The results were not quite as good as we may have hoped for, with only a 34% in-calf rate. That’s not as high as we would like, and we are still not sure if it’s a synchronising issue or a semen issue, but we are determined to stick with it. The level of genetic gain you get with the heifers and sexed semen represents a couple of years’ gain in one,” says Nicole.

For the past two seasons, they’ve also put the balance of their herd to Wagyu genetics. The offspring are a high-value Wagyu-cross calf, which Warren and Nicole sell for a premium to a rearer at five days old. 

They appreciate it’s an option not available to all dairy farmers in all areas, but the opportunity generates a premium, reduces potential bobby numbers, and generates an income to help fund the sexed semen programme through the remainder of the herd and heifers. 

Tidying up the late-calvers is done using Hereford genetics to make the distinction from Wagyu clearer at birth. 

“We manage to sell about 80% of them too. They are generally good, rearable white face calves, and the markings define them well from the Wagyu,” explains Nicole.

Gold-standard calf care 

With their breeding programme producing more valuable replacement calves, more calves for beef, and fewer bobbies, the couple have also refined their rearing process. It’s a simple stepped approach that staff engage well with – one that keeps calf health front and centre.

“It is helped by us both working together on it. That’s probably quite unusual, but it works well and we leave the rest of the team to manage the milkers and bring the calves and cows in from the paddocks,” says Warren. 

Preparation well before calving includes laying fresh wood chips through the 14-bay rearing barn, ensuring each pen has a water supply and meal box in place from day one. Wood chip is a perennial favourite thanks to its ability to absorb moisture and be easily refreshed between mobs of calves. 

Thanks to some well-coordinated teamwork between contract milker Dan Burrows and his team, who collect the calves, on arrival at their pens they’re efficiently allocated to their rearing area. Wagyu, replacements, and bobbies are penned separately.

“The level of genetic gain you get with the heifers and sexed semen represents a couple of years’ gain in one.”

After formerly owning multiple farms, Warren says he loves being able to concentrate on one farm now, rather than feeling “spread thin”

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Achieving the highest-quality colostrum has become a lighthearted competition between the team

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Getting more sexed heifer replacements out of their heifers is a major aim for Warren and Nicole

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“They will be tubed with colostrum on arrival and sprayed with a dot to confirm they’ve received it, and be blood-tested to prove they’re at their required colostrum level. We treat that first colostrum dose as vital; regardless of the calf’s type, it sets them up so well,” says Nicole.


Last year, they recorded no outbreaks of rotavirus or salmonellosis among the calves reared. Nicole attributes that to calves receiving a good level of quality colostrum early on, and a strict regime of spraying out pens weekly with Virkon and topping up the wood chips with fresh batches.

They’ve ensured their staff are well-engaged with the colostrum’s importance, turning the colostrum testing regime into a bit of a competition to see who can achieve the highest, healthiest levels at test time. 

“They enjoy the competition, and understand the science behind it too,” says Nicole.

Rearing to go

Warren and Nicole’s sole focus for spring is on the calf rearing. That gives them the time and space to “take as long as it takes” to ensure the calves are all capable of drinking on their own, are looking healthy, and well on their way as a mob before being moved into dedicated paddocks.

Every week the local vet team comes in to humanely disbud and prevent horn growth, sedating the calves and using a local anaesthetic to minimise pain and stress. 

Once they’re happy with each group of calves, the animals are moved into dedicated calf paddocks. North-facing shelters are popular with the calves during the nights. In-paddock feeding of milk tails off as the calves approach 80kg, and none are sent to the grazier until they hit 100kg.

Simple system, tight team

Warren and Nicole are quick to point out their system has few complexities in a process they’ve been fine-tuning for three seasons. 

Nicole attributes it to a good farm team backing them up, taking care to bring calves in regularly, and being invested in the value of high-quality colostrum in those early hours of life.

“I think if there was anything else we would like to work on, it would be just getting more sexed heifer replacements out of our heifers,” she adds.

“We treat that first colostrum dose as vital; regardless of the calf’s type, it sets them up so well.”

Warren and Nicole’s calf-rearing tips 

  1. Care about colostrum Ensure the first feed of colostrum is with the best quality, and check its quality regularly with a Brix refractometer, a cheap but worthwhile investment. 
  2. Get a good system going Ensure the collection team knows the collection process, and what the rearing team can expect when each shift starts: calves that are tubed for colostrum, in the right pen, ready to be reared. 
  3. Keep things clean Ensure pens are clean, topped up with shavings between mobs, and use a Virkon spray to reduce risk of disease.
Farm Facts

Warren Thomas and Nicole Mayberry


Farm owner (Warren), calf rearers


Charing Cross, Canterbury

Farm Size:

294ha HERD: 1000 milkers


480,000kg MS/year

Nicole and Warren with farm assistant Max Mitchell and herd manager Tim Madden (far right).

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Aerial view of 294ha Westingdon Farm

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Max, aka ‘Maxinator’, is into his third season on the farm and Warren says he’s growing in confidence all the time.

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Once spring arrives, Warren and Nicole devote most of their time to rearing the calves together.

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Page last updated:

19 Jul 2023


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