20 August 2024
Will and Alex Prichard calve 500 cows in a spring block at Escalwen, near Letterston, and also run two 200-cow autumn calving herds.
That high throughput of calves can present disease challenges - in the three years to 2023, calf mortality from neonatal diarrhoea averaged 9.5%, peaking at 16% in 2022 when the herd was subject to bovine TB movement restrictions.
“Over my entire farming career, one of the most depressing things I have experienced is when calf rearing goes wrong and when mortality and sickness in calves becomes almost insurmountable,’’ said Mr Prichard.
In an attempt to correct weaknesses in their system, in 2023 the Prichards and their calf rearer, Tom Phillips, embarked on a new feeding programme guided by veterinary consultant Ryan Davies.
They invested in two pasteurisers, part funded by the Welsh Government Small Grants - Efficiency scheme, feeding cow transition milk enriched with whole bovine powdered colostrum after calves had received their colostrum feed.
Transition milk is produced by the cow from the second milking after calving, up to the sixth, and contains a higher percentage of milk solids, antibodies, vitamins and minerals than milk produced after this point in the lactation.
It also has elevated levels of growth factors, natural antimicrobial proteins and other bioactive substances.
But the quality of transition milk is highly variable. That, in conjunction with the transfer of passive immunity (TPI) from colostrum dictating a calf’s antibody levels, will make a significant difference to health and performance.
If calves don’t receive sufficient antibodies, they are more likely to die, suffer from diarrhoea or respiratory issues, and require treatment with antibiotics.
Taking blood samples from calves and using IgG as a biomarker to standardise transition milk is one solution and this is what the Prichards did, supported by the Farming Connect ‘Try Out’ Fund, an initiative that funds individuals and groups of farmers and growers to experiment with ideas and bring them to life.
Throughout the calving season, Dr Davies took daily blood samples from newborn calves in their first 24 hours.
The results showed that 21% had an excellent TPI, 7% good, 41% fair and 31% poor.
“This is about average for the UK and good for a dairy block calving herd,’’ said Dr Davies, of Veterinary Technical Consulting Ltd.
The total solids in the pasteurised transition milk were measured with a Brix refractometer and, depending on the reading, it was enriched with a colostrum powder from SCCL to standardise it to a minimum of 12.5% Brix or 14.5% milk solids – instead of powder another option is to add whole milk colostrum.
“If we didn’t reach that threshold we added whole bovine colostrum powder to it to increase the Brix reading,’’ Dr Davies explained.
“The average Brix for the milk at Escalwen was 10.5% so we raised that to 12.5%, but every farm will be different.’’
Other parameters used for the milk were a total bacterial count of under 100,000 colony-forming units (cfu)/ml, a total coliform count of less than 10,000 cfu/ml and no antibiotic residues.
“It is important that calves aren’t fed any antibiotic residues because they inhibit the growth of the normal healthy gut microbiome,’’ said Dr Davies.
The milk was fed to calves up until day 10.
This approach resulted in a significant improvement in calf health and a major reduction in mortalities.
Mortality resulting from neonatal diarrhoea reduced from an average of 9.5% to 3% and antibiotic usage in pre-weaned calves to 16%, from the five-year average of 45%.
Importantly, no highest-priority critically important antibiotics (HP-CIA) were used
pre-weaning in 2024; in 2022 use of these had hit a high of 1.98mg/PCU.
Although feeding transition milk comes with some additional cost, from labour and equipment for its collection through to storage and heating, Mr Prichard said the improvements had completely changed the mood on the farm during the calving period.
“Once you get your head around how important IgGs are, it almost becomes a passion to harvest as much of that IgG as you possibly can and utilise it in your own herd.’’
As well as transition milk feeding, improvements were made to hygiene and cleanliness to reduce the disease challenge.
Pasteurising the milk was a “game changer’’, he added, to reduce disease risks such as Johne’s and bovine TB.
The milk was pasteurised for 60 minutes at 60°C to destroy pathogens including mycoplasma, salmonella, E. coli and listeria.
Pasteurising at higher temperatures or for a longer duration can reduce antibody levels, although studies have shown this is more effective in the destruction of Johne’s and bovine TB organisms which can be detected after heating to 60°C for 60 minutes.
Top tips for feeding transition milk
Adhere to good hygiene practices when collecting and storing prior to feeding
Heat to the correct temperature before feeding
Take the health status of the herd into account to reduce risk of disease transfer, particular if pasteurisation is not used.
In systems that feed calf milk replacer instead of whole milk, the equivalent mass of milk powder should be removed and replaced with colostrum powder to maintain the solids percentage and prevent osmotic diarrhoea.