Extensive chapters cover everything related to the digestion of the horse and what we feed them. The anatomy of the horse relating to digestion is outlined first, from the head, teeth, and salivary glands, to the stomach, intestines and colon. The exact process of what happens where, when and why is detailed.
This is followed by the chemistry of feed as it relates to the digestive process. This includes discussion on carbohydrates and dietary fibre, compounds in feed, and fats and oils.
Chapters which will be of great interest to performance horse owners are on supplements, energy and protein metabolism, and on energy from feed. How to predict gross energy (GE) and digestible energy (DE) is discussed in depth and follows on to metabolisable energy and net energy. Several trials and studies are quoted. It can be complicated but it is worth understanding the needs of an animal we expect to perform to the highest of standards but who has been taken from its natural roughage-based environment.
The mineral nutrition chapter gives in depth explanations of the minerals important to the horse. These include calcium and phosphorus, magnesium, sodium, potassium, sulphur, and chloride, sulphur, zinc, manganese, iron, iodine, and two of the most commonly misused and misunderstood, copper and selenium. Each mineral is explained in relation to the horse. FOr example, the apparent absorption of copper in horses is estimated to range between 14 and 50% (compared with ruminants, at 4-6%), depending on the presence of other minerals. There is also evidence that the absorption of copper declines with age. The relationship between copper and osteochondrosis is also discussed.
The fat-soluble vitamins A, D, E and K lead off the vitamin chapter, followed by water-soluble vitamins including Thiamine, Riboflavin, Niacin, Biotin, and Folic acid. We know these names, but are we aware of what a horse's requirements are?
Finally, the book points out that there is no right or wrong way to feed a horse - but is also stresses "that 'an average horse' does not exist", and making up feeds without the background knowledge relating to feed types, composition and individual animal requirements "can lead to great mistakes".
Eight keys steps are given for making up a ration, and it is noted that how the horse is kept must be taken into account. Performance horses are often stabled for many hours a day. But, the authors write, quoting a 1996 study: "The strong instinct or 'need' to forage and search for food has been demonstrated.
"A need for shelter from weather conditions rarely overruled the needs of 'locomotion' and 'foraging' in previously stabled horses, which chose to spend only an average of 4.5 hours of cold, wet, and windy nights inside a dry shelter provided with hay.
"However, the need for a dry lying place was seen as a prime motivation for short-term shelter seeking."
Julian Hill is a senior lecturer in Animal Nutrition at the University of Melbourne.