NEW ZEALAND - Supplementing pasture-based diets does not boost milk production to the level many New Zealanders expect, according to an expert dispelling the 100g milksolids to kilo dry matter “myth”.
Even under ideal conditions, offering supplements returns at most an additional 70-80 grams of milk solids per kilo dry matter and sometimes only 55grams on commercial farms, says Dr Jane Kay of DairyNZ.
Records typically show better yield responses on small farms, where supplement loss is limited and pastures are managed intensively to manage waste and maintain quality.
The key factor is maintaining pasture intake and avoiding substitution – the reduction of pasture intake when supplements are fed.
Two other reasons for not achieving a large boost from supplements could be supplement wastage and energy put towards pregnancy or body condition gain – not milk production.
Dr Kay highlighted grazing residuals as being key in showing how hungry cows are and the amount of substitution that could be taking place, lowering the milk solids response from feed.
She said: “The hungrier the cow, the lower the grazing residuals, the lower the rate of substitution, and the greater the MS response.
“For example, a herd of cows in spring previously eating down to residuals of 1400kg DM/ha would produce an extra 70g MS if one kg of high energy supplement (e.g. barley) was fed. However, if pre-supplement residuals were 1800kg DM/ha, the MS response to this extra kg DM supplement would be 20g or less.”
TheCattleSite News Desk
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