She cites a published paper at last year's Australasian Dairy Science Symposium.
"The paper's hypothesis was that heifers that achieved 90 per cent mature liveweight at calving could produce an extra 2-2.5kg MS per kg of liveweight over an average life of five lactations, compared to being behind target," says Sarah.
"So, for a 50kg improvement to achieve target weight, that would translate to 100-125kg MS over five seasons."
Grazier relationship
Over a period of two months, at the end of 2013, Sarah met 100 farmers, graziers and rural professionals to explore the dairy farmer/grazier relationship. Their responses highlighted the need for examples of graziers that were doing well, which led to the focus farms.
"One of the top reasons farmers gave for heifers not being raised as well as they could, was the gap in relationships between parties," says Sarah.
"Specific answers ranged from not having an agreed contract to having different expectations, like who was responsible for supplying extra feed."
Sarah says the purpose of the focus farms -- in Northland, King Country, North Otago and Manawatu -- is two-fold.
"We really want to provide farmers growing heifers with better information and allow them to share their experiences with others. Up until now there has been a knowledge gap in this area.
"The other goal is to strengthen relationships between graziers and dairy farmers. Are expectations being met from both sides and, if not, why not? These focus farms will help us delve into some of these issues and create tailored resources to address some of these questions."
Tips for dairy farmers who graze heifers off-farm
Farmers with well-grown heifers use both minimum age and minimum weight targets for weaning calves off milk.
Heifers should be transitioned to an all-grass diet for a couple of weeks or meal should be sent with the stock to prevent reduced growth when relocating heifers to grazing.
Be clear with expectations. Communicate what the expected weights are for the end of the grazing term.
Weighing is the only objective way to assess that heifers are growing well and on target.
Animal health plans should be specific to the farm the heifer is being grazed on. Parasite pressure and mineral deficiencies are unique to each farm.