Farmer Wilson Ronald celebrated his birthday docking sheep with his family in Western Southland earlier this month.
The family docked some of the 1750 Texel Coopworth lambs on their 84ha farm Wilrock, in Fairfax.
The flock was docked in accordance to new government rules, which came into effect in May.
Under the Ministry for Primary Industries regulations, a sheep's tail cannot be docked shorter than the distal end of the caudal fold.
"It's a pain in the arse ... but it's the rules so you've got to do it," Wilson said.