What key attribute is important for good quality hay?

The key attribute of good quality hay being leafy with easily identifiable, intact plants is paramount for several reasons. Leafiness indicates that the hay has retained a significant portion of the plant's nutritional value since leaves are where much of the plant's nutrients are stored. Intact plants also suggest that the hay has been harvested and processed correctly, minimizing the loss of essential nutrients.

Well-preserved plant structure is an indicator of careful management and proper curing techniques. When plants are damaged or broken, not only can this result in nutrient loss, but it can also lead to mold and spoilage, making the hay less palatable and potentially harmful for horses. Additionally, easily identifiable plants help ensure that the hay is free from weeds or undesirable species that could detract from its quality or safety.

While the other attributes like protein content, color, and moisture content are indeed important factors to consider in evaluating hay quality, they do not encompass the fundamental aspect of what makes hay beneficial for horses—its structural integrity and nutrient retention embodied in its leafy, intact state.