The primary effect of diary on cows life wouldn’t be the cow that’s milked, it’d be on the calves. I suspect it’d be more than 1⁄2 of a calf per human milk lifetime.
Is the question how many calf-equivalents map to current dairy consumption, or to the counterfactual dairy consumption of someone trying to reduce other animal products without going vegan?
The primary effect of diary on cows life wouldn’t be the cow that’s milked, it’d be on the calves. I suspect it’d be more than 1⁄2 of a calf per human milk lifetime.
Claude guesses 2-3 calves
Some quick-mafs.
Assuming the use of a high milk yield breed like Holstein Friesian cows.
18KL per lactation: https://www.australiaslivestockexporters.com/holstein-fresians-dairy-cattle/
About 217 ml of milk, 23.6g of cheese (equiv to 236ml milk) and 21.4g of yoghurt (about 21.4ml of milk) are consumed per Australian per day: https://www.statista.com/statistics/1143391/australia-dairy-mean-daily-grams-per-capita-by-food-subgroup/ = (approx) 474ml = 0.47L
Australians live about 83 years, approx 30k days.
30kDays * 0.47L/Day = 14100L of milk over a lifetime. Or a bit less than one calf.
The average Holstein cattle has parity of < 2.7 (https://pmc.ncbi.nlm.nih.gov/articles/PMC8369829/). So we can estimate something like one third of a dairy cow per person, and a little less than one calf.
Is the question how many calf-equivalents map to current dairy consumption, or to the counterfactual dairy consumption of someone trying to reduce other animal products without going vegan?
EDIT: Nvm, this dataset was of a niche religious group (The seventh day adventists), I should’ve read more throughly before commenting.
Assuming no major dietary differences between vegetarian converts, and lifelong vegetarians, it appears that they consume less dairy by about a half: https://pmc.ncbi.nlm.nih.gov/articles/PMC4232985/#!po=39.8438
So, assuming that someone moves to the mean lacto-ovo vegetarian diet, you can assume about one half calf less over a lifetime.