A PROJECT using GPS technology to track the movement and grazing behaviour of dairy cattle has raised questions about the way farmers manage their cattle in large herds.
Dairy SA and Dairy Australia's GPS Cows project, conducted by Best-biz senior consultant Les Sandles, analysed the behaviour of three dairies in the Lower South East.
Donovans Dairy, Donovans, and Berko Pastoral, Mount Schank, were chosen because Dr Sandles had worked with them for many years.
They had similarity in management, large herd sizes of between 1800 and 2200 cows, and a similar feeding program - grain fed in the dairy, followed by a partial mixed ration and then paddock grazing.
A smaller dairy was chosen as a 'reference herd'.
Owner Michael Leese, Kongorong, milks 170 cows, and feeds a ration in the dairy, a bale of hay in the paddock at night, and heavily relies on grazing.
This is about the median dairy practice in the country.
Dr Sandles documented distances and speeds traveled by the cows, and identified modified behaviors between leaders and followers in the herd, including how long the cows spend lying down, grazing, feeding on the feedpad and, importantly, the number of hours during the day that they are unable to either feed or lie down.
He said one of his more "selfish" motivations for the project was his growing feeling that as farmers tried to facilitate higher production and balance a ration more carefully, it paradoxically increased the number of cows that were not getting a balanced diet.
"In these herds, roughly a third of the diet gets fed in the dairy, a third on the feedpad, and a third in the paddock," he said.
"There was a concern that as we changed the ration around we weren't getting the responses we were expecting.
"As the ration improved, more cows showed us they weren't coping so well with it even though they were still doing most things pretty well.
"We started to figure that the behaviour we wanted on both the feedpad and in the paddock was being compromised to the extent that some cows may not be eating on the feedpad and just eating grass and others might be eating on the feedpad and not eating grass."
Dr Sandles said the more obvious part of the problem was that cows were walking long distances to the paddock but perhaps more importantly, the amount of time spent standing in the dairy yard, feedpad and walking meant they looked for a place to lie down in the paddock rather than graze.
"Where there was a big gap between the first and the last cows being milked and their access to the feedpad, and with herd behaviour coming to the fore, we think late cows might be dragged off the feedpad if all their mates are already on their way to the paddock," he said.
"Therefore the late cows may not get a chance to eat that part of the ration."
This belief was affirmed to some extent by one of the project findings, which was that the behaviour of the first cows to be milked and the later cows to be milked was dramatically different.
Dr Sandles said the data suggested this was not so much influenced by herd size or distance walked in the day, but had more to do with the time lapsed between the first and last cows milked.
"What it's really saying to us is that to get all the cows to behave in the same way, we need herds to be split into much smaller management groups for feeding and milking," he said.
"There's a need for us to look at what the cost benefit is of increasing the speed at which cows go through the dairy, so either bigger dairies or smaller mobs.
"Both of them pose capital issues in either labour or plant and equipment, but to do anything radical we have to look at the economics of the data and try to make some assessment of what an hour is worth."
Dr Sandles said this may force farmers to look at milking each mob in an hour or so.
"It's not so much the mob size, it's how long it takes for them to go through the dairy, so the dairy will dictate the mob size," he said.
"I think if you can milk them in an hour, they're not standing around too long."
Another key finding from the project was that as the distance cattle walked out to the paddock increased, grazing behaviour disappeared.
While we might have a romantic notion that cows get out to the paddock and explore their surroundings while foraging, Dr Sandles said this was not the case for most of the herd, perhaps with the exception of freshly calved heifers.
"Instead of meandering around grazing, we have quite direct lines of movement," he said.
"They'll graze to a water trough, to the end of a paddock and back to the gate, but they don't criss-cross the paddock as well.
"That's in stark contrast to where you've got no feedpad involved, no distance involved and smaller numbers involved. They do explore the paddock much more then."
The project may shed some light on another issue that has been troubling Dr Sandles.
He is developing a theory that early lactation, high-production cows may be walking at the expense of milk fat.
High genetic merit cows are designed to milk hard in early lactation and prioritise glucose for this purpose.
They essentially have no alternative but to use milk fat as energy rather than losing milk volume.
He said with cow diets so heavily focused on producing milk through nutrition, their bodies are looking to other sources of energy for walking, the most optimal being fat that would be pumped into milk.
This, he said, was compromising fat tests and, in turn, returns on milk components.
"Instead of fat going into the vat it's going into their legs," he said.
"While my feeling is that there is going to be an improvement in production by reducing the distance walked, it's more likely to come through fat tests than volumes."
As a result of this, Dr Sandles said he would now rethink the partial mixed ration and dairy ration to make each of them more of a mini complete feed.
"At the moment I look at the overall 24-hour balance, but I might have to start looking at 3-6 hour balances," he said.
