The diet does not provide enough protein. A low protein intake has many effects for horses. For young growing horses body growth and muscle development will be affected negatively. For broodmares low protein is connected with early embryonic resorption, low foaling weights and poor milk quality. For performance horses insufficient protein effects recovery and development of muscle. Low protein may affect all horses through a reduced appetite, weakened hooves and dull coat.
Increase the protein content of the diet through use of higher protein feeds and supplements such as soyabean meal. Consider higher protein forages such as alfalfa or earlier cut haylages. Analysing your forage for protein is important as it provides a significant contribution to the daily diet.