Effect of level of feed intake and gelatin supplementation on growth and quality of hoofs of ponies.

A pelleted ration was fed limited or ad libiturn to two groups of seven Shetland 8month-old ponies for 117 days. During the last 56 days, gelatin was added to the diets of four animals in each of the two intake groups. Gelatin was added at levels of 30 and 90 g per 100 kg body weight for the first and second 28-day periods, respectively. Ponies fed the diet ad libitum consumed 180% more feed, had 50% greater rate of hoof growth (.384 +.009 vs .254 • .008 mm/d), 200% greater increase in height at the withers and 425% greater increase in body weight than ponies fed the limited level. The hoofs of ponies fed ad libitum had 82% greater surface area at the sole border than those fed limited amounts. The addition of gelatin did not affect (P<.05) hoof growth, base area, compression strength (yield point or elasticity), moisture, iron, zinc or nitrogen content. Rate of hoof growth declined with age. Hind hoofs grew faster than front hoofs. Sex of animals did not affect hoof growth or quality. The average compression yield strength of hoof wall was 146 + 5 meganewtons per meter (mN/m2). The tangent modulus of elasticity just prior to failure was 3.722 • .111 mN/m 2. Neither yield strength nor elasticity were changed by level of diet intake or gelatin supplementation or by iron, zinc, or nitrogen content of the hoof wall. The zinc content of the hoofs of l imited fed ponies (136 + 3 ppm) was higher (P<.01) than those that were fed ad libiturn (114 +2 ppm). Hoof nitrogen, and moisture content were not different (P<.05) between groups. Hoof wall iron content was greater for limited fed ponies. Nitrogen content averaged 17.7 + .1%. Moisture content of all postmortem hoof samples averaged 27.8 • .2%. Specific gravity of limb bones was greater (P<.05) for the ponies fed ad tibiturn. (