The origin of this phrase is debated, but here are some of the most common theories:
* Oxen as symbols of strength: Oxen were traditionally used for heavy labor and were known for their strength and resilience. They were considered symbols of good health and vitality.
* Oxen's diet: Oxen were often fed a diet of high-quality hay and grain, contributing to their robust health. This association with healthy eating may have contributed to the idiom.
* Oxen's longevity: Oxen had a relatively long lifespan compared to other livestock, further reinforcing the notion of their good health.
It's likely that a combination of these factors contributed to the use of "healthy as an ox" to describe a person in excellent health.
It's worth noting that the idiom "healthy as a horse" also exists and likely has similar origins.