Driftless SW Wisconsin | Yes, surface area to volume ratio does obviously get lower as cow gets larger and a larger cow may, in total/year around, be better suited to very cold climates like Alberta. Yet the smaller surface area to volume ratio is also obviously better suited to warmer climates. So from this logic there is a continuum of preferred cow sizes from north to south, depending on whether the primary annual concern is heating vs cooling. Adding to the mix is the logical difference in metabolic rates between individual cows and large and small cows as groups... In the end though, I am convinced, from my own scale data, in my WI location with my Hereford cows, that calf 205 day AWW is NOT linearly related to cow size and in my production system that -I am going to wean more pounds of calf PER GRAZING AND HAY ACRE from 1300 lb cows than I am from 1800 lb cows. |