26 March 1999

Delayed harvest can be beneficial

DELAYING harvesting fermented cereal whole-crop to increase dry matter % helps boost feed intake and milk yield when fed to dairy cows. But it does not alter the composition or levels of milk fat and protein.

According to CEDARs Richard Phipps, whole-crop trials conducted as part of a two-year MDC-funded project are helping clarify the effect of dry matter on feed intake and animal performance.

In trials at CEDAR, using Holstein Friesian dairy cows, feed intakes increased from 10.9kg DM/head/day for 30% DM whole-crop to 13.7kg DM/head/day for whole-crop treated with urea. Urea can be used to produce an alkaline feed which can boost intakes of grass silage.

Similarly, milk yields rose from 27.9kg/cow/day to 29.2kg/cow/ day for cows in early lactation on low and high DMwhole-crop, respectively. Milk fat and protein did not alter significantly, said Dr Phipps.

While treating whole-crop with urea to produce an alkaline feed appears to be beneficial boosting milk protein compared with high DM fermented whole-crop, it has disadvantages. Lower starch in urea-treated whole-crop reduces feed value, and there is also a higher risk of nitrogen being excreted by stock to which it is fed, said Dr Phipps. "Thats increases feed losses and is not a good environmental message," he commented.

The advantage of harvesting more mature whole-crop to increase DM yield/ha is attractive, but Dr Phipps warned that tests to establish the ME value of higher dry matter crops were unreliable. This may affect ration formulation giving too high an ME value and this should be taken into account, he said.