Dr Racheal Bryant and Paige Fisher – calves kept with cows for the first 10 weeks will be followed right through to joining the herd themselves.
A Lincoln University study is comparing three rearing methods for the first 10 weeks of a calf’s life. Anne Lee reports.
Lincoln University is doing a bit of what-if scenario testing, keeping calves on cows until weaning at about 10 weeks of age.
The study at the university’s Ashley Dene Research and Development Station isn’t designed to test the practicalities of carrying out the practice with big numbers but with its group of 15 cows and 15 heifer calves it will surely give some insights into the challenges and opportunities of pasture-based dairy suckling systems.
Dr Racheal Bryant is leading the study which is comparing several outcomes for both cows and calves under three different calf rearing scenarios.
The control is a typical system where calves are separated from their mothers within a few hours of birth and reared with six litres of milk per calf (20% of initial body weight) per day and weaned at about 10 weeks of age when calves are about 80 to 90kg.
The second scenario also sees the calves removed from their mothers but they are fed a high milk allowance of nine litres per calf per day (30% of initial body weight).
Racheal says they’ve had no problem getting calves to drink their full allowance.
In both scenarios the calves are fed on automatic calf feeders so each calf’s intake is well controlled and monitored through electronic identification eartags read by the automatic calf feeder when the calf enters the feeder.
Under the third scenario where calves are still with their mothers and feed ad lib, it’s estimated that by about six weeks they’re drinking about 10 to 12 litres per day.
That’s based on herd test data comparisons from a previous study run last year.
Interestingly some calves in the suckling group have shown signs of nutritional scours at brief times.
Racheal says they’re looking at the differences for the cows and calves across a range of factors.
Over the calf rearing period they’ll compare growth rates up till and beyond weaning between each calf rearing system.
They’ll also compare passive immunity in the calves through blood sampling.
Indications of rumen development will be by blood sampling and measuring beta hydroxy butyrate levels as well as using accelerometer eartags to determine rumination and grazing activity.
All calves in the study are heifers so the intergenerational effects of the different calf rearing systems can also be compared.
Once calves have grown and entered the milking herds in 2024 their milk yields and reproductive performance will be monitored and compared with the calves reared under the other two scenarios.
They’ll be compared over their lifetimes to gauge if there are any long-term effects.
Racheal says the cow-calf contact group are together “24/7” for the first six weeks except for the short time cows leave the paddock for milking.
The calves are separated from their mothers at the gate to the laneway with fencing along the laneway calf-proof.
Research technician Paige Fisher says initially cows were vocal immediately after they left the calves at the gate but they quickly settled and made their way into milking without fuss.
The cows are milked once-a-day (OAD) in the morning for the first six-week period.
A towable shelter is positioned near the break cows are being fed on so calves can shelter during bad weather.
Cows are managed with typical one-wire electric fencing and calves can move freely under the wire, often nestling down in the longer covers of the next break.
Paige says the cows make soft closed moth vocalisations to call calves and louder open-mouthed calls when agitated – for instance at the gate when calves are separated.
By late August there hadn’t been any incidences of cows bullying calves.
“We’ve seen calves get a short shift from a cow if they’ve snuck in to attempt a feed from a cow that’s not their mother but nothing too rough,” she says.
Two cows, though, were discounted from the trial group after initial selection because while they showed interest in their calves it was evident the calves weren’t suckling, so the calves were removed to the pens to ensure they received colostrum.
At the six-week mark calves will be separated from their mothers at night as the transition begins to making the calves nutritionally independent from their mothers and weaning.
The cows will move to being milked twice-a-day at the six-week mark and the calves will be removed for the night.
They’ll have access to hard feed, grass and water during the night.
The fencing system will allow cows and calves to see and touch each other through the fence but calves won’t be able to drink from their mothers.
By 10 weeks the calves will be fully weaned and separated from their mothers.
The cows’ live weights, milk yields, milk composition, udder health, somatic cell count, incidence of mastitis and post-partum anoestrus period will all be monitored and recorded to see if suckling their calves has any effect.
Cows are fitted with pedometers and their activity pre and post weaning and the shift to night separation will be recorded too.
Racheal says they’ll watch for any changes in milk yields around those times along with milking duration and milk flow rates.
“We’ll be looking at a lot of those practical aspects that might impact the adoption of a cow-calf contact system,” she says.
