TMR isn’t just for grown-ups. But finding a ration offering quality and the right intake factor for consistent growth rates is vital.
However, putting heifers on a TMR isn’t just a case of recycling the milking cow leftovers, or adding more chopped straw to an adult ration. They need diets balanced for developing rumens, says independent nutritionist Rodney Allen.
He has discovered switching well-grown calves onto a TMR at 12 weeks of age doesn’t produce the right results.
“We found calves scoffed and looked happy, but didn’t grow as well as they should. The problem was on a diet of 3-4kg a day of rearing pellets, concentrates made up 80% of the diet dry matter. In the TMR it was only 40%. So although bellies were full and calves content, they couldn’t eat enough energy because of the smaller rumen capacity at that age. Concentrate intakes were half of what they were.”
Mr Allen therefore devised a mix where half the diet dry matter came from concentrate, with an additional top dressing of rearer nuts on the mix for the first two to four months. Once calves reached six months of age, rumen development had progressed enough for them to be eating sufficient TMR to get their concentrate intakes.
Another concern for year-round calving herds is the impracticality of making up several rations for batches of different sized heifers, so diets were based on the farm’s forages and a protein and a mineral source.
“We then made a base balanced ration for the middle heifer, typically 14-15% protein and of 9.5 to 10.5 MJ/kg DM energy density, altered accordingly for size.”
HALL FARM HEIFER TMR in 100kg mix
“When short of staff and with so many different age groups to feed, it’s easier to fill a feeder wagon for 269 heifers. The problem with feeding dairy cow leftovers to youngstock is they are inconsistent: One day you might have 200kg over, another day 400kg. Our heifers are now on a fully-balanced heifer ration and we see even growth among the age groups,” he explains.
“The other advantage is heifers are used to the TMR when they come into the calving yard; rumen bugs are used to the products. We never see a displaced abomasum. Animals are bigger, healthier and milking quicker. They seem to take off after calving with the heifer group averaging 34 litres a day, with some giving 50 litres a day.”
After weaning at about eight weeks, calves are reared on a proprietary nut and ad-lib straw diet with summer grazing on local marshes. From about seven to eight months, a TMR is introduced at winter housing in October.
“We just give them a sprinkling of TMR and still keep feeding the rearer nut then gradually lift the quantity of TMR as they eat more and stop feeding the nuts. Between 12 and 24 months, heifers are eating from 25kg to 35kg/head/day of TMR,” says Mr Clarke.