Vitamin A is a crucial fat-soluble vitamin for horses, playing a vital role in their overall health and well-being. While horses that have access to green forage can obtain sufficient Vitamin A through carotene conversion, those fed poor quality roughage or lacking access to green forage may require supplemental Vitamin A. However, it’s important to be cautious of potential toxicity when supplementing Vitamin A in addition to a well-fortified grain base. This article will explore the role of green forage, causes of Vitamin A deficiency, and total dietary requirements for horses of different activity levels and life stages.

Role of Green Forage in Meeting Vitamin A Requirements

Green, leafy roughages provide carotene, which horses can convert into Vitamin A. However, bleached, weathered, or dark and dusty roughages do not contain sufficient vitamin content. When horses have access to good quality green forage, they can generally meet their Vitamin A needs. But if a horse is fed poor quality roughage, supplementation becomes necessary.

Causes and Symptoms of Vitamin A Deficiency in Horses

Many horses experience Vitamin A deficiency due to consuming hay stored for extended periods. Commercially prepared grains often include Vitamin A to address this deficiency. However, it’s essential to avoid overdosing horses with high-potency vitamin supplements when they are already receiving well-fortified grains.

The signs of Vitamin A deficiency in horses include dry, scurfy skin and hair coat, runny eyes, and night blindness. Studies have shown that night blindness can be induced by Vitamin A deprivation and reversed by adding sufficient Vitamin A back into the diet. Other symptoms may include dry and scaly hooves, increased susceptibility to respiratory infections, stress, and diarrhea. Toxicity symptoms may include dry hair, anemia, and increased bone size.

Total Dietary Requirements for Horses

According to the 2007 NRC Guidelines, the total dietary Vitamin A requirements for an 1100lb horse are as follows:

– Maintenance horses: 15,000 IU per day
– Moderately active horses: 22,500 IU per day
– Pregnant/lactating mares: 30,000 IU per day

Additional Vitamin A is crucial during the last 90 days of pregnancy, lactation, and for high-performance horses and weanlings.

Vitamin A plays a vital role in the health and well-being of horses. While green forage can meet their Vitamin A requirements through carotene conversion, horses fed poor quality roughage or lacking access to green forage may require supplemental Vitamin A. It’s important to be cautious of potential toxicity when supplementing Vitamin A on top of a well-fortified grain base. By understanding the causes and symptoms of Vitamin A deficiency, horse owners can ensure their horses receive adequate nutrition for optimal health and performance.