The 1000 year medieval period is marked by revolutions in agriculture, including:

• invention of mortar board plow

• inventions in animal harnessing leading to productivity leaps

• shift to 3 field tillage

• development of varied cereal crop types

• expansion of water-driven mills

• expansion and enforcement of exclusive rights of nobility to hunt

• development of fish ponds

All of these lead to significant changes over time which affected animal husbandry, farming and the general peasant availability of and access to meat.

I'm going to ask you to be more specific about what period you mean by 'medieval peasant'. It changed a lot.