How do you know when a sheep is up for a romantic interlude? It’s a big issue for the US sheep farming industry where up to a quarter of rams have such flagging libidos they ignore the come-on from ewes. Now, John Stellflug and a team from the US Agricultural Research Service’s Sheep Experiment Station in Dubois, Idaho, say a quick injection can spot a randy ram. Injecting a drug called naloxone stimulates the ram to produce testosterone. The levels of the hormone produced indicates how likely it is that the ram will be sexually active.
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