A study was made of the chemical composition and energy value of the whole, empty body, and of the relative size of certain organs in 11 ponies ranging in full-body weight from 81 to 259 kg. The fatty acid composition of various adipose tissues was examined in three ponies.
Ingesta-free body weight (Y) was found to be highly predictively related (r2 = 0·) to the full-body weight (X) in accordance with the equation, Y = 0·9678X–10·41. The gastrointestinal contents constituted 9·65 ± 3·44% of the full-body weight.
Despite the heterogeneous nature of the population examined and the small range in body fatness (6·6% to 18·9% of ether-extractable lipids in the empty body), 93·3 % of the variation in the concentration of body fat was associated with the variation in the concentration of water. The mean fat-free, empty body contained 70·7 % of water, 22·6 % of protein and 6·0 % of ash. Of the variation in the weights of water, fat, protein, ash and energy, 97·0%, 64·5%, 91·0%, 85·2% and 87·0%, respectively, were ascribable to the variation in empty-body weight.
For the conglomerate body, the calorific values of protein and fat were 5·381 and 9·311 kcal/g, respectively.
The ranges for the mean percentage contents of major individual acids in the fatty acids of five adipose tissues were: oleic, 29·5–33·3; palmitic, 26·1–28·0; linoleic, 17·1–24·0; palmitoleic, 6·2–9·5; and linolenic, 3·8–10·2. In one animal the depot fats contained relatively high concentrations (8·6–12·0 %) of linolenic acid; the concentrations of palmitic and linoleic acids were correspondingly lower than those of the depot fats of the other horses.
Tissue weights of various segments of the gastrointestinal tract were linear functions of body weight. About 87 % and 82 % of the variation in the weights of liver and kidneys respectively, was associated with the variation in full-body weight.