New research a win-win for dairy farmers

New research reveals a method for farmers to achieve higher weight gains when feeding their heifers, while causing less environmental pollution.

Lincoln University’s Dr (Paul) Long Cheng and Dr Jeffery McCormick from the Faculty of Agriculture and Life Sciences are confident dairy farmers stand to gain from their new research.   

Their study found dairy replacement heifers grazed on dual purpose cereal and brassica crops, such as wheat and canola, achieved higher weight gains and caused less environmental pollution.

A dual purpose crop is one which is grown in summer/autumn to be grazed as forage before continuing to grow prior to being harvested for grain production.

Dr Cheng says every year farmers needed to rear dairy heifers as replacements for their milking herds as part of their farm management routines.

“Providing adequate high quality feed for these heifers is crucial, so they can reach their target live weights at critical stages of their growth and development.”

He says their ability to reach these target live weights has significant implications for their successful mating and milk production in the subsequent lactation. 

“We also know that rearing dairy heifers contributes to the environmental impact of dairy production, particularly nitrogen leaching, through the excretion of urinary nitrogen.”

He adds pollution is lessened through reduced urinary nitrogen excretion than heifers grazed on conventional pasture.

To find the solutions to these challenges, Dr Cheng and McCormick and their team undertook a trial to examine if feeding the heifers different types of forages such as dual-purpose crops, like cereals and brassicas, would increase their live weight gains and reduce urinary nitrogen excretion.

The trial involved three groups of dairy heifers, all equally matched for live weight and their genetic ability as breeding cows.

Each group was randomly allocated and fed a different type of forage, a pasture (perennial ryegrass/white clover), a cereal (wheat) and a brassica (canola).

Dr Cheng says at the end of the trial, his team discovered heifers grazing on either wheat or canola showed increased live weight gains and lower urinary nitrogen excretion to the environment in comparison to the pasture-feed animals.

“This type of regime had been used in Australia for over 20 years on mixed cropping farms, but this is the first time it has been used for dairy replacement stock in New Zealand.

“These dual purpose crops haves been shown to have an additional environmental benefit is an exciting discovery and will benefit dairy farmers throughout New Zealand.”

He says local farmers are already interested in trailing these crops with their heifers.

Jwalls@nbr.co.nz

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