No Horns vs Horns & Overheating

[Nanno]

I agree. Horns are only one aspect of body heat regulation. Our goat Finn has the biggest horns in our herd but has a much harder time with heat than Sputnik or old Cuzco (who had only one skinny horn). Finn is pitch black across his hindquarters and although his hair is short and sleek, it is incredibly thick. Cuzco was black across the hindquarters as well but his hair was not as thick as Finn's. Also, let's face it--Finn tends to be overweight and Cuzco was almost never overweight. Sputnik is overweight but has a roan coat with a lot of white hair that reflects the sunlight. Even a little white hair interspersed with the black makes a huge difference in helping a goat stay cool. Ears are another aspect of heat regulation. Notice that desert breeds such as the Nubian, Boer, and all the goats from India and the middle east have enormous ears. Yet most of them actually have very small horns. I even read a study that claimed wattles are significant in heat radiation even though that makes no sense to me.

I sometimes wonder if big horns attract more heat than they disperse. Horns are dark so they heat up significantly in the sun. This can be great in winter but not so great hiking in summer sun. The cold climate Swiss breeds all have bigger horns than their desert cousins. I'm not sure how significant this is, though, because many other species of horned animals from desert climates have gigantic horns, and some cold climate species have tiny ones (think mountain goats). Mountain goats and mountain sheep evolved in similar climates and look at the differences in horn size! Because of all these differences, I think horns can't be as significant to heat regulation as we tend to believe. I think body color actually makes the biggest difference, with coat thickness and fitness being two other factors that are more important than horns.