If "for a cow" the lifetime emission is the same (say because the daily emission halves but the cow lives twice as much), then the rate of emission "for the ent

If "for a cow" the lifetime emission is the same (say because the daily emission halves but the cow lives twice as much), then the rate of emission "for the entire herd" will also be the same (everyting else being equal). The herd will contain two "low-emissions" cows for each "high-emissions" cow.