Saturday, March 30, 2024

Autumn calving in Tasmania

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A simple but comprehensive programme takes cows from being dry to starting milking in top condition, Van Diemens Land farm manager Hugo Avery says.
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He manages four properties, one of which is the 461ha Island View dairy farm in Woolnorth, northwest Tasmania, where up to 1000 cows will be run this season. He told the Australian Dairy Conference in Geelong earlier this year the farm was converted to dairying in 1995, but until 2010 was run as a split-calving operation, with 66% of the herd calved in spring and 34% in autumn.

Since then all the herd have calved in autumn with planned start of calving on April 1 and drying off about the end of January. While cow numbers have stayed stable production has lifted 35% to come close to 400,000kg milksolids (MS) in 2013-14, an average of 40kg MS/cow or 983kg MS/ha. Jan and David Johnston have been 32% sharemilking on the farm since 2006.

The herd is split in two with one made up of heifers and lighter older cows. They’re fed some of the 300 tonnes drymatter (DM) of pit silage and 60t DM baled silage made every spring along with 1.2t of concentrate/cow fed in the dairy. The lead feed mob also gets 300t DM of hay, bought in from off the farm and 10% of the property is also sown into turnips as a summer crop.

As there’s no feedpad, hay and silage are fed in the paddock where utilisation rates can be between 50 and 85%.

The transition diet for the cows is 1kg each of premix pellets which include anionic salts and canola meal mixed with 2kg grain. The cows are also offered ad-lib hay and minimal pasture for at least 21 days before the expected calving date. Rising two-year-old heifers are fed on observation of signs of springing.

The hay and grain fed is tested for DCAD levels and this season it’s planned to also take plant tissue samples to be tested to get even more accuracy. Avery said the cost of AU$600 for testing all hay which came on to the farm was well worth it as some big differences in DCAD levels had been shown.

After calves are removed from the lead feed mob, with cows taken to the dairy and fed concentrate, the new mothers are drafted out to go into the colostrums mob while the rest go back to their paddock for a new break of pasture as well as more hay. Cows remain in the colostrum mob for four to five days, where they’re fed ad-lib pasture, hay and 4-5kg grain/day before moving into the main milking herd. The pasture the cows graze in the lead feeding period won’t have had potassium or nitrogen applied or effluent spread on it for at least three months previously.

Close monitoring allows for early intervention if animal health problems start to show up. Every lead fed cow is teat sprayed every day which resulted last year in just one case of clinical mastitis and eight sub-clinicals. The average somatic cell count was 119,000 cells/ml.

Last season 425 heifer calves were reared to an average weight of 124kg before going to the Van Diemens Land heifer rearing unit which supplies replacements, as well as stock for future dairy conversions the company has planned.

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