From D&H site:

With a unique formulation of high fibre, micromanaged cereals and high oil, Staypower Muesli is perfect for providing a controlled and slow releasing fuel, even for horses with sensitive digestive systems. 

• Ideal for eventers, endurance horses and those requiring stamina.
• Provides a blend of antioxidants and over 25 vitamins and chelated minerals to support muscular, hoof, coat, immune and joint health.
• Promotes post-work recovery and hydration due to our leading recovery package of micromanaged cooked cereals and electrolytes.
• Added L-Lysine for muscle development and maintenance.
• Suitable for excitable or fizzy horses and ponies.
• Developed alongside years of research into performance horse nutrition.