In addition to fresh meat and milk, which as food items are not the topic of this section, livestock farmers and artisans used further animal ingredients as tendons, horn, bones, bladders. Complex technical constructions as the composite bow were based on combination of animal and plant based materials. The current distribution conflict between biofuel and food production is being described as Food vs. fuel. Conflicts between food needs and usage, as supposed by fief obligations were in so far common in historical times as well. However, a significant percentage of (middle European) farmers yields went into livestock, which provides as well organic fertiliser. Oxen and horses were important for transportation purposes, drove engines as e.g. in treadmills.