“Bon Appétit” - how to encourage and maintain appetite throughout the season
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By Catherine Rudenko
Encouraging and maintaining appetite throughout aseason can become a serious challenge. The best planned feeding program in the world is of no use if the horse simply does not eat as required to sustain performance. There are multiple factors that can lead to poor appetite for horses in training – some relating to health, some relating to physical properties of the feed or forage, along with behavioral considerations.
What is a normal appetite?
Grain-based feeds are an important requirement for a horse in training.
Before we can fairly state a particular horse has a poor appetite, we must first have an idea of what a normal appetite range is. The horse has a given capacity within its digestive tract and an appetite appropriate to this. Horses will typically consume 2-3% of their body weight each day on a dry matter basis – in other words not accounting for fluid intake or any moisture found in the forages. This equates to 10-15kg (or 22-33lbs) per day for a 500kg-weight (or 1100lb) racehorse. As fitness increases, it is normal for appetite to reduce, and most horses will eat closer to 2% of their body weight. The energy requirement of a horse in training is such that they dependent on a large amount of grain-based “hard feeds,” which for the majority form 7-9kg (or 15-19lbs) of the diet each day. With a potential appetite of 10-15kg (or 22-33lbs) we are, for some individuals, running close to their likely appetite limit. The most immediate effect of a reduction in appetite is the reduction in energy intake. Horses require a large amount of calories, typically 26,000 to 34,000 cal per day when in full training. Comparatively, an average active human will require only 3,000 cal per day. Just one bowl of a racing feed can contain 4,500 cal, and so feed leavers that regularly leave a half or quarter of a bowl at each meal time really can be missing out. Forage is equally a source of calories, and a reduction of intake also affects total calorie intake.
• Physical form of feed and forage
The physical form of the bucket feed can affect feed intake due to simple time constraints. Morning and lunch time feeds are more common times at which to find feed left behind. Different feed materials have different rates of intake – due to the amount of chewing required – when fed at the same weight. To give an example, 1kg (or 2lbs) of oats will take 850 chews and only 10 minutes to consume in comparison with 1kg of forage taking up to 4,500 chews and 40 minutes to consume. Meals that require a high amount of chewing – while beneficial from the point of view of saliva production (the stomach’s natural acid buffer – can result in feed “refusal” as there is simply too much time required. Cubes are often eaten more easily as they are dense, providing less volume than a lighter, “fluffier” coarse mix ration. Inclusion of chaff in the meal also slows intake, which can be beneficial, but not for all horses. Any horse noted as a regular feed leaver ideally needs smaller meals with less chewing time. Keeping feed and forage separate can make a significant difference. The choice of forage is important for appetite. Haylage is more readily consumed, and horses will voluntarily eat a greater amount. The study below compares multiple forage sources for stabled horses. Another factor relating to forages is the level of NDF present. NDF (neutral detergent fiber) is a lab measure for forage cell wall content – looking at the level of lignin, cellulose and hemi-cellulose. As a grass matures, the level of NDF changes. The amount a horse will voluntarily consume is directly related to the amount of NDF present. Analyzing forage for NDF, along with ADF, the measure relating to digestibility of the plant, is an important practice that can help identify if the forage is likely to be well received. Alfalfa is normally lower in NDF and can form a large part of the daily forage provision for any horse with a limited appetite. As alfalfa is higher in protein – should it become a dominant form of daily fiber – then a lower protein racing feed is advisable. Racing feeds now range from 10% up to 15% protein, and so finding a suitable balance is easily done.
• B vitamins
B vitamins are normally present in good quantity in forages, and the horse itself is able to synthesize B vitamins in the hindgut. Between these sources a true deficiency rarely exists. Horses with poor appetite are often supplemented with B12 among other B vitamins. Vitamin B12 is a cofactor for two enzymes involved in synthesis of DNA and metabolism of carbohydrates and fats. Human studies where a B12 deficiency exists have shown an improvement in appetite when subjects were given a daily dose of B12.(3) As racehorses are typically limited in terms of forage intake and their hindgut environment is frequently challenged, through nutritional and physiological stresses, it is reasonable to consider that the racehorse, while not deficient, may be running on a lower profile. Anecdotal evidence in horses suggests B12 supplementation positively affects appetite as seen in humans. Another area of interest around B vitamin use is depression. Horses can suffer from depression and in much the same way as in the human form, this can affect appetite. …
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