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How a Young Foal Grows
The period of maximum risk for the development of skeletal abnormalities occurs when weight gain is high. Thus it is critical that we understand and manage this period of rapid growth because as well as size and weight, we must be concerned about soundness.
Height and weight are important but maximum growth rate is not compatible with optimum skeletal development. A delicate balance is required between not feeding quite enough to achieve best results, and over feeding just enough to cause developmental bone diseases.
Foals do not grow simply in weight and size – they also have specific development at specific times. The tissues and organs of the body grow at different rates.
Body composition – fat or muscle and bone: Whether a young horse develops muscle and bone or lays down fat is determined by the quality and quantity of protein in the diet. Quality refers to the type and amount of essential amino acids in the protein. foals synthesize only half of the 22 amino acids required for bone and muscle growth. The other 10 must be supplied in the diet – hence they are called essential amino acids. We supply protein in the diet; we are in fact attempting to meet essential amino acid requirements.
Every protein in the body has its own formula of amino acids and protein synthesis is so specific that if the feed has only half the required amount of a particular amino acid, body protein synthesis may be reduced by up to 50%. Unused amino acids are converted to energy and stored as fat – making them unavailable for muscle and bone growth and increasing “cover”. This affects bone and muscle growth in the young foal because although the feed tag may say 16% protein, it may only be 8% usable. Another factor affecting the ability of the young foal to utilize the dietary protein is the protein digestibility.
The site of digestion plays a major role in whether foals absorb essential amino acids from the diet. Protein not digested in the small intestine is converted to ammonia in the large intestine and essential amino acids are lost to the foal.
Regular monitoring of weight, growth rate and height – using scales and /or condition scoring – are sound management practices. But, foals do not grow simply in weight and size. The tissues and organs of the body develop at different rates.
Maximum bone growth occurs from 3 months before until 9 months after birth; muscle from 2 months before birth until 22 months of age and fat deposition begins from around 9 months onwards. If nutrition is unbalanced or incorrect during these periods, the opportunity to achieve optimum muscle and bone development will be missed and body composition will deviate from ideal.
Close attention needs to be paid to the diet and exercise. Adjustments to energy and protein intake are required to accommodate changing musculo-skeletal development and pre-training while recognizing the need to protect immature joints. Growth rate declines in the 12 – 15 month old foal and fewer nutrients are required to support skeletal growth and muscle development. In addition risks for developmental orthopedic diseased decrease with increasing skeletal maturity.
An enormous amount of nutrients are required for growth in this way as energy to fuel the process, and protein and minerals to make the conversion.
foal development
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