Dairy farmers could improve the lifetime milk yield of their cows and improve profitability by paying more attention to the nutrition of heifers from birth to first calving, according to American dairy expert Judd Heinrichs, professor of dairy science at Pennsylvania State University.
Correct feeding could boost returns in the first lactation by as much as £250 a cow from a combination of improved feed conversion efficiency and higher milk yields, Prof Heinrichs told more than 100 dairy farmers at a meeting organised by Harbro on the farm of Blair and Gregor Colquhoun at Dendoldrum, Inverbervie.
“At current early culling rates, half the lifetime of a cow is non-productive before she produces her first calf,” Prof Heinrichs pointed out. “This is a huge cost on every litre of milk produced and is second only to the cost of feed.
“The aim must be to reduce the age when the first calf is born and cut the cost of feeding without impairing the cow’s future production potential.”
US dairy farmers had reduced age to first calving by three days a year for the past 18 years and were now calving cows almost two months earlier at 22-24 months. “And we should be looking to get at least four lactations out of each cow rather than the current average of less than three.”
Ensuring calves received adequate colostrum, and the right type of colostrum, in the first 24 hours of life was vital. “It is essential calves receive 2-3 litres of good quality colostrum within two hours and 5-6 litres in the first eight hours,” he said.
It would also be worthwhile, he suggested, to measure protein content by taking blood samples as colostrum from Holstein cows tended to be lower, and was in inverse proportion to yield. Trials had shown the mortality rate of calves receiving less than 10g of protein a litre doubled compared with this receiving more than 10g.
“When you are selecting Holstein genetics, you are actively selecting for poor quality colostrum,” he warned. “The protein level of colostrum is diluted in higher yielding cows.”
Calves could also be weaned as early as four weeks – which the best managers were achieving in the USA – rather than six weeks provided they were eating at least 0.75-1kg of concentrates a day.
“The aim at this stage should not be to maximise growth rate, but to grow the rumen to cope with cereal-based feeds at a later stage,” he said. “The calf kept on milk for too long is the most expensive dairy replacement on the farm. Feeding too much milk is costly and inhibits intake of technically formulated starter pellets designed to grow the rumen. Calves may look better on milk and will grow faster up to weaning, but will be lower yielders as heifers.”
Precision feeding was essential to grow heifers to puberty at about 10 months old, he said. The aim should be a daily gain of 800g on a high protein and energy diet with forage intake, including straw, kept to a minimum. Feed should not be made available ad lib to heifers, but restricted to a maximum of eight hours a day to limit intake, provided adequate feeding space is available.
“Trials have shown that 800g a day is the optimum,” Prof Heinrichs said. “A daily gain of less or more than 800g results in reduced milk yield in the first lactation.
“The penalty for three management mistakes – incorrect feeding of the heifer, calving a month later than the optimum and growing 45kg heavier than required – is costly and will affect the cow for the rest of her working life,” he added.