I asked the high school student (from Nambour State High, where they keep cows) who was supervising my handiwork closely "how many litres can you get from one milking", and after some consultation, I was given the answer - 25 litres (!).
I said that seemed an awful lot, but I was assured that a cow's milk producing parts extend way, way up inside her. I was given the impression that the tank, so to speak, extends well beyond the udder.
But, while not wanting to question the standards of Kevin Rudd's alma mater, I think the student was a bit misleading.
As far as I can tell, from this detailed slide show from the University of Wisconsin, where they seem to know a thing or two about cows, there are bits that help suspend the weighty udder that extend way up the internals of a cow:
but the parts that produce the milk are pretty much in the udder area:
In any event, on the question of how much milk you can get from a cow in a single milking, given that there are normally two milkings a day, and there are sites saying that an average cow can produce 35 to 50 litres a day, 25 litres at once seems certainly a possibility, if on the high side of the range. It's remarkable to think that, at a generous household consumption of 2 litres a day, one cow could make enough to keep 25 families happy.
While looking into this, I discovered that the Israelis are actually world leaders in coaxing high yields out of cows:
The average cow in Israel produces 12,000 litres of milk a year, double what Australian dairy cows produce, at 5,500 litres a year (Dairy Australia 2014).
It could provide useful lessons for Australia, with our similar climate.
"The Israeli dairy industry is cutting edge technology for dairying," said Dr Ephraim Maltz, of the Institute of Agricultural Engineering at Israel's Volcani Centre.
Israel has pushed the boundaries of what dairy cows can do.Now, 12,000 litres a year is about 33 litres a day, if you count every single day of the year. But as I think they are "rested" before being pregnant again, this isn't inconsistent with a higher yield when they are milked. One animal's rights site says cows on average are milked 10 months of the year, so in Israel, that would indicate an average of 40 lives per milking day. Why is the Australian figure in the ABC report above much lower than that? Do they have more rest periods per year?
As just mentioned, the amount of milk cows are now enticed to produce is the subject of criticism from animal's rights groups. It is a pity that unwanted calves are killed at a very young age - something I have noted here before. In fact, it seems we don't even eat the meat ourselves:
Most will be destined for the slaughterhouse within days of birth. Bobby calf meat is considered to be of low value and is predominantly exported as ground beef and offal to Japan and the US.Hence there is an ethical reason for the search to make a genetically engineered, yeast based, milk equivalent. Good thing I handled a teat while there was still time...