Commercial dairy farmers should be aiming for a 365-day calving interval to improve yields, milk price and consistency in herd efficiencies in order for cows to spend more time in a year as a high yielder.
That was the message from dairy veterinary consultant Dr Tom Chamberlain who told farmers at the Mole Valley Farmers Lifetime Dairy Conference that this was ‘achievable with effort’ for commercial herds producing an average of 9,000-10,000 litres, but anything below 400 days was a good starting point.
He said: “For example, over a lifetime, a cow at fewer than 370 days could potentially have five lactations, compared to a cow at 450 days, which only manages four lactations.
"This could equate to almost 39,000-litre lifetime lactation compared to 36,000 litres with a wider calving interval.”
Dr Chamberlain used an example milk price of 30ppl to highlight that by reducing calving interval by 85 days, milk value could increase by £1.24/day.
He said although feed costs had the potential to rise in line with achieving high yields for more of the year, a tighter calving block would mean more calves produced.
“A tighter calving interval can mean greater choice when it comes to cow selection, as there are more animals on the ground,” he added.
“There is generally a huge amount of selection pressure on the male side to use the very best bulls, but not so much for females.”
On-farm actions to reduce calving interval
■ Have a clearly defined voluntary waiting period. As a starting point, this should be about 40-42 days and moved back once calving interval is tightened up
■ A pro-active veterinary programme is needed for cows not seen bulling. Anything at 50-55 days which has not been seen bulling should be put up to the vet to make sure there are no problems
■ Look at the interval between successive serves to evaluate heat detection. An interval about 21 days indicates good heat detection, but at 42 days that heats have been missed
■ Conception rates could be considered, but are not a ‘go-to’ solution to improve calving interval, as long as consideration has been given to controlling infectious diseases and the method and processes used when serving cows
■ Look at the spread of calving interval to assess the cost of fertility across the herd