As long as we've had farming, we've had to transport animals and we've come a long way from the small coastal vessels known as 'mosquito fleets' that used to transport livestock before the advent of road and rail. And the days of droving 2,000 cattle from the Far North to Whangarei (as Ken Lewis did in 1982) have gone the way of the dodo.
The evolution of livestock transport has been aided by improved technology. By the 1930s there were simple flat decks with detachable wooden stock crates which could hold around 100 lambs. Cattle weren't carried by trucks until larger rigs were introduced around the 1950s.
Articulated truck-and-trailer units which could carry more stock were introduced in the 1960s. Then, from around the 1970s, in came the big rigs that were able to transport 600 prime lambs, 400 ewes or 40 cattle. Triple-level crates could be converted to double-deck for cattle and the crates were removable and for trucking firms it meant freight could be carried outside of the stock season and so help make the business more viable.
If trucks and stock numbers became bigger so did the amount of effluent produced during a journey.
One doesn't have to be very old to remember travelling behind a fully-laden stock truck and coping with the resulting smear on the windscreen and splats on the bonnet but amazingly it was only 10 years ago that an industry code to deal with the problem was finally introduced.