With the onset of a ‘quota-free’ milk market the economics of future heifer rearing may strongly encourage producers to calve their heifers down at 22 to 24 month of age.
Matt Palmer, ruminant nutritionist with Harbro, says herds producing between 7,000-12,000 litres will typically be targeting first calving at 24-30 months.
But to get an earlier calving age, Mr Palmer says figures from DairyCo suggest Holstein heifers will need to bulled at 15 months, weighing 420kg and with a wither height of 130cm (51in) to achieve a 24 month pre-calving weight of 635kg and a wither height of 140cm (55in).
He says: “The economic benefits of calving at two years are well documented, showing increased lifetime production, a speeding up of genetic improvement and a reduction in the fixed costs associated with heifer rearing.”
He adds the first 12 weeks of a calf’s life is crucial when targeting this earlier first calving.
“The foundation of successful calf rearing is the first 12 weeks when ‘feed efficiency is between 50 and 60 per cent, compared with less than 10 per cent from 12 months old until calving.”
“Key to achieving maintenance and growth in the first 12 weeks is to follow an ‘enhanced’ calf growth programme using high quality milk replacers and calf starter feeds.
“To maximise growth rate potential of more than 0.75 kg per day, calf milk replacers need to be fed to provide 750-900g solids per day usually in five to six litres.
“In cold weather and temperatures below 10degC, be prepared to increase the milk replacer by up to 100g/day to provide extra energy as calves have limited ability to keep warm at low temperatures.”
He says, ideally, calf milk replacers which are specifically for heifer rearing should be whey-based, with a high protein of 26 per cent and low fat of 16 per cent.
“These milk replacers are designed to give much heavier heifers at weaning with better development of udder secretory tissue.
“Research has shown whey-based replacers cause less risk of digestive disorders and intakes of calf dry feeds and roughage occur sooner than with replacers based on skim milk powder, which can form a clot in the calf stomach and reduce appetite.
“These replacers benefit from being manufactured at low temperatures to protect protein quality, which in turn improves protein absorption and enhances frame development.”
Alongside feeding a specific calf milk replacer, Mr Palmer advises introducing a calf starter pellet at three to four days of age right through to 12 to 16 weeks.
“Pellets which incorporate coarsely ground, rather than finely milled raw materials, will give an increased ‘scratch factor’ within the pellet to stimulate early rumen development.”