Water: The Overlooked Nutrient

Introduction

The need for water is one of the basic motivating forces for all animals. Only a lack of air and severe pain initiate a greater response by animals than thirst. Thus, one of the five freedoms in evaluating animal welfare adopted by the UK Farm Animal Welfare Council is the "freedom from thirst, hunger and malnutrition" (Webster, 1996). However, there are contradictory views on how much water a horse needs and how best the water should be delivered.

Contradictory views on horse watering are not new. Twenty years ago, Hinton (1978) in a review of watering methods of horses, stated "the literature published over these last 150 years provides confusing and often conflicting advice on the ideal way to water horses". More notably, Hinton implied that many of the "gold" standards that we accept for watering of horses are not based on science but are simply anecdote and tradition repeated so often that they have become the "rule." It is important that scientific, not anecdotal, evidence is used whenever welfare issues arise in horse husbandry. Few studies have been conducted on watering of horses since Hinton's review but my research group has recently looked at water requirements and water delivery systems for horses (Freeman et al., 1998; McDonnell et al., 1998). These data will help in the interpretation of water needs of horses.

Thirst Versus Water Appetite

What is thirst? By definition, true thirst or primary drinking is the desire and/or discomfort caused by the need to replace fluid lost from intracellular and extracellular body stores. However, secondary drinking or an appetite for water is also described. Animals or humans with an "appetite" for water, drink for the pleasure of the experience not because their cells require fluid replacement. An afternoon spent in the saloon is an example of appetite not thirst. Similarly, horses may develop "appetite" for water. This will be described later (behavior section) and can be "normal" or "pathological."

Why is Water so Important for Life?

The absence of water causes death more rapidly than the absence of food. Water is vital because the bodies of adult horses are about 70% water. Fat adult horses have slightly less water per unit weight (55-60%) because fat holds less water per unit than does muscle. Newborns, whose body fat is low (2.5%), have a very high water content (~80%). Based on these numbers, a 500 kg (1100 lb) horse in moderate body condition is about 350 kg (800 lb) water. A 50 kg (110 lb) newborn is about 40 kg (90 lb) water.

Water is the main component (65%) of the cell (intracellular fluid or ICF). The remaining water is in extracellular fluid (outside the cell). The extracellular fluid (ECF) includes the blood, the lymph, the fluid between cells (interstitial fluid) and the gut. A 500 kg horse has about 227.5 kg of ICF water and 122.5 kg in the ECF. Most of the ECF is blood and intestinal water.

Blood is about 8% of body weight or 40 L of the ECF (40 kg in a 500 kg horse). One of the overlooked reservoirs of body water is the horse's gut. Water content of the intestine varies but can be as high as 100 L of water. Diet affects gut fluid content. Meyer (1995) in Germany showed that light horses fed hay had 78 L of intestinal water whereas gut water in grain-fed horses was only 50 L. He also observed that a 20-hr water restriction had a lesser effect (10% decrease) than did exercise (15-20% decrease) on gut water. Roughages promote the storage of more water in the gut than concentrate diets.

Message: Because a horse is composed mostly of water, water is needed to keep the horse healthy.

What is Water Balance?

Water balance in the body is not static. Fluid is transported from the gut into the bloodstream and then into cells. The fluid exits the cells and is excreted. Water balance is the state in the horse when water intake equals water excretion. A horse gets water in three ways: drinking (liquid or free water), eating (feed water) and metabolizing (metabolic water). Water loss can occur in 4 (or 5) ways: feces, urine, breathing, evaporative loss (sweating) and through milk in lactating mares.

Water Intake by the Horse

Horses get most of their water by drinking liquid water. Another route of water intake is from the feed it eats. Metabolic water is water generated by the biochemical processing of digested nutrients. Metabolic water is fairly constant at about 2 - 8.5 L per day.

In Western Canada during winter, when horses are fed hay, free water accounts for 85-90% of total daily water intake by horses. Horses grazing lush pastures, however, drink less liquid water because pasture can supply up to 80% of a horse's daily water needs. Horse owners are sometimes perplexed by these observations. The best analogy is that of eating crackers compared to eating lettuce. Hay (crackers) contains about 10% water whereas pasture (lettuce) has 65 to 80% water. A 500 kg horse that eats 10 kg (22 lb) of hay obtains 1 L(0.25 gal) of water. To obtain the same dry matter, the horse eats 26 kg of pasture. But, pasture has 65% moisture, so it supplies 17 L (3.5 gal) of water. Therefore, the pastured horse needs to drink less water than the hay-fed horse. This applies only to lush pasture, not to winter pasture which should be thought of as standing hay.

Message: Liquid water is the most important source of water for hay-fed horses. However, pasture can supply a large amount of the daily water needs of a horse because of its high moisture content.

Water Loss from the Horse

The amount of water lost in the manure will depend on the horse's diet, its water intake and whether gastrointestinal disease is present. About 70 - 80% of the water that is consumed daily is excreted in feces and urine. However, the route of excretion is affected by diet. On most grass hay diets, fecal losses account for 80% of the total water excreted (or about 50 - 65% of total water consumed). But when alfalfa hay is fed, fecal losses and urinary losses can be about equal. A 500 kg horse voids about 20 kg of manure a day. Therefore, water loss in manure in a horse fed grass hay is 13 - 15 kg (~ 3 gal) per day. Manure is wetter in horses fed grass hay (75% moisture) and driest in horses fed high grain diets (50 - 65% moisture).

The volume of urine voided by horses depends on diet (protein, mineral), water intake and renal function. Many equine specialists overlook the importance of diet on urine volume. A horse fed alfalfa voids twice the urine volume of a horse fed timothy hay even though both drink about the same amount of water (Table 1).

Table 1. Diet effects on water intake, fecal water and urine output (L/d)

	Alfalfa	Brome	Hay-grain pellet
Water intake	29.3	28.9	16.7
Fecal water output	9.1	14.7	4.8
Urine output	13.6	7.9	9.4
*Based on a 500 kg horse (modified from Cymbaluk, 1989)

Sweat and breathing produce insensible water losses. These routes account for about 25% (2 - 8.5 L/d) of a horse's daily water exchange. Heavy exercise increases excretion by both routes of water loss.The fluid demands of pregnancy are not large. The fetal fluids in a mare are about 10 to 23 L. However, milk production by mares puts enormous demands on water intake. A 500 kg mare produces about 3% of her body weight (about 15 kg [3 gal] for a 500 kg mare) in milk per day.

Message: Manure is the main route of water loss in horses fed grass hay diets.

How Much Water Does A Horse Need?

The amount of water a horse drinks depends on its body weight, its diet, the ambient temperature, its function (e.g. pregnant, lactating, performance), disease (diarrhea, pituitary tumours) and its behavior.

A key factor that determines the amount of water a horse drinks is its body weight. Table 2 gives the minimum, maximum and average water intake for horses of various size as cited in the Recommended Code of Practice for Horses (AAFC, 1998). Although average water intake by horses is 5.5 L per 100 kg BW, the minimum and maximum values reflect the wide individual variability of water intake by horses.

Table 2. Water Requirements of Horses*

Body Weight	Minimum	Average	Maximum
410 kg (900 lbs)	13.5 L (3 gal)	20 L (4.5 gal)	27 L (6 gal)
545 kg (1200 lbs)	18.0 L (4 gal)	27 L (6 gal)	36 L (8 gal)
680 kg (1500 lbs)	22.5 L (5 gal)	36 L (8 gal)	45 L (10 gal)
820 kg (1800 lbs)	27.0 L (6 gal)	43 L (9.5 gal)	54 L (12 gal)
* Modified from Recommended Code of Practice for the Care and Handling of Farm Animals: Horses (1998, p 4).

Diet is also important in influencing water intake by horses. Feeds, however, have different effects on water intake by horses. The amount of dry matter eaten is important but so are fiber and mineral (e.g. salt) content. Unlike water intake, urine output, is mostly influenced by mineral and protein content of the diet. Horses fed long hays such as timothy or alfalfa will drink about 3.2 L per kg of feed eaten. Yet, horses fed high grain diets drink 30-40% less water (2 L/kg feed) than those fed hay diets (Table 1). Processing feed alters the fiber component and often, reduces the amount of water consumed. Horses fed long hay drink 27% more water than those fed pellets.

The air temperature at which the horse is kept affects water intake. Horses drink 400% more water if temperatures increase from -18° to 38°C (NRC, 1989). By comparison, yearling horses drank 15-20% less water at -5°C compared to 10°C (Cymbaluk, 1990).

The horse's function such as lactation and exercise increases water intake up to 300%. Lactating mares drink 50 to 300% more water than non-pregnant horses. Exercise or work can double and triple water demands. Horses on long, intense rides have much higher water needs than horses on a leisurely stroll. Horses in endurance events are reported to lose up to 22 kg (50 lb) of fluid after a day's ride.

Gastrointestinal disease especially severe diarrhea can double the water loss in feces. Horses with diarrhea that maintain their appetite and continue to drink water can compensate by concentrating urine but once a horse stops drinking, severe dehydration occurs quickly.

Message: Water requirements depend on body weight, diet, temperature, lactation, exercise or work, and disease. Average water intakes are about 5.5 L/100 kg BW (0.5 gal/100 lb).

Drinking Behavior of the Horse

Ontogeny of drinking
Ontogeny is the development of an adult physiologic response. Suckling foals on pasture have been reported not to drink water until weaning (Crowell-Davis et al., 1987), but we have observed 2 - 4 wk old foals drink water if the water bowls or tanks were easily accessible. Australian workers also reported that suckling foals on pasture started drinking water by 3 wks of age (Martin et al., 1991). Water-seeking by foals depends at least in part on the amount of milk the foal gets from its dam. Eating solid feeds will stimulate foals to drink water. For example, week old orphan foals fed milk replacer drank about 5 L/day (1 gal) of water once they began eating solid feeds (hay, pellets).

Frequency and duration of drinking bouts
Horses on pasture drink as infrequently as once per day. Hay-fed, stabled horses drink as infrequently as 3 to 4 times per day or as frequently as once per hour. The total time spent drinking in a day is very small. Mares allowed continuous access to water drink for 14 min daily; those on intermittent systems drink about 7 min per day (McDonnell et al., 1998). Water intake by horses was nearly identical in both watering systems.

Hay-fed horses drink water while they eat or after they eat (meal-associated drinking). Drinking while eating dry feed aids chewing and swallowing, and dilutes the high osmotic load of a meal. Thus, when placing water bowls in a stall, a management choice must be made whether to locate the water bowl near (to aid chewing) or away from the feed bunk (to control water spillage and soiling of the water bowl).

Individual, daily and seasonal variation in drinking patterns
Our studies have shown that individual mares of a similar size have a wide range in daily water intake (Freeman et al. 1998). For example, one 550 kg mare with a daily average of 32 L had a range of daily intakes from 30 to 37 L over a week of observations. A similar-sized mare on the same diet drank an average of 28 L/day with a range from 24 to 32 L/d over the week. As indicated above, the average water intake by horses is 5.5 L/100 kg BW. However, water intake for individual horses varied from 3.3 L/100 kg BW to 6.7 L/100 kg BW daily (see Table 2). These ranges are similar to those recently observed in pregnant mares (Freeman et al., 1998).

We also characterized the patterns of daily water intake in horses fed four times daily and given continuous access to water. Patterns differed slightly between heavy versus light mares but in both types 86 to 92% of water was consumed between 6 AM and midnight. From midnight to 6 AM, very little water was consumed (only 2 L of a total daily water intake of 28 L).

Water intake decreased 15 to 20% in pregnant mares from the 5th (fall) through 9th (spring) month of pregnancy. Factors affecting the drop in water intake may include a lower dry matter intake and hormonal changes. A similar drop in water intake occurred in yearlings from fall through winter and was attributed to low ambient temperatures (Cymbaluk, 1990).

Abnormal water intake by the horse
Abnormal, excessive water intake in the horse is termed psychogenic polydipsia. Horses with this condition drink more than 100 L water daily. They excrete vast volumes of urine. This condition can be caused by an "appetite for water", overeating salt, or may be a medical problem such as diabetes insipidus. Psychogenic polydipsia in a POA pony was diagnosed when the owner reported that the pony was eating 2.5 kg salt per week! Normal salt intake for this size of pony is about 0.5 kg per week. Compulsive water drinking is a condition described in humans with psychological disturbances. It is unclear whether this condition exists in horses, but there are clinically normal horses that drink high volumes of water and yet retain a normal serum osmolality.

What Type of Water Delivery Systems Should be Used for Horses?

Outdoor water supplies such as dugouts, ponds, streams and rivers are suitable water supplies for horses on pasture during the summer. Man-made or natural water sources must be constantly replenished through precipitation or underground aquifers. Disruption of water supply during droughts and extreme cold must be prevented. Snow is not an acceptable substitute for water although it may at times supplement water intake. Surface water sources should be fenced off to limit manure and organic matter contamination. Unexpected sources of water contamination include decaying wildfowl carcasses which have lead to deaths in livestock from botulism.

Well water is the most common source of water in barns and paddocks. The type of water delivery system used in a barn will depend on barn management. The simplest water system is the manual system using a water bucket. The disadvantage of a pail is that is must be manually filled and carried. An advantage of bucket watering is that the horse's water intake is known. Adipsia (failure to drink) is a sure sign of illness.

Automatic watering bowls (two cup and large stock waterers) constantly refill but in an unheated barn can freeze if not equipped with heaters. Any float, paddle waterer or water valve system can be used. Most horses can learn to use any type of water delivery device but a horse provided with a new watering bowl should be watched until it has mastered the device. By using a timer, water can be provided at intermittent intervals. Timers can prevent barn floods and stop horses from playing in the water bowl.

In box-stalls or straight stalls, individual waterers can be placed away from the feeder (to lower water bowl contamination) or near the feeder (to lessen walking across the stall) according to the manager's preference. The water bowl should be positioned at a height in the stall that allows the horse to drink comfortably.

Large capacity waterers (5 to 50 gal) can be used in pastures and corrals. One large automatic watering bowl will serve 20 adult horses and 30 yearlings or foals. The waterer can be built into the fence line thereby supplying water to two corrals. Fence line bowl placement also helps control pawing by young horses. A concrete apron built around the waterer protects the device. Electrical heat will keep water pipes from freezing in winter but must be properly grounded to prevent electrocution.

Adequacy of Water Intake (Is your Horse Drinking Enough?)

Water intake measurements
If you have an outdoor watering tank, ask yourself these questions: how long does a tank of water last? How often and how long does each horse drink? Do the horses fight for water? If you are unsure of the water intake by your horses, water meters can be attached to the water pipes and intakes monitored for a week. Not all water meters are reliable, especially at low flow rates, so test the meter before you use it. Paddle-wheel water meters can be inaccurate.

Clinical assessment
If you have an outdoor watering tank, ask yourself these questions: how long does a tank of water last? How often and how long does each horse drink? Do the horses fight for water? If you are unsure of the water intake by your horses, water meters can be attached to the water pipes and intakes monitored for a week. Not all water meters are reliable, especially at low flow rates, so test the meter before you use it. Paddle-wheel water meters can be inaccurate. The following clinical measurements can be conducted by anyone. Skin turgor evaluates hydration. Take a pinch of skin (on the neck, shoulder, over the eye), twist it and take the time required for the skin to return to normal. A time longer than 2 seconds suggests mild dehydration. Are the feces dry and firm (low water), or watery (excess water, disease)? Is urine output low (low) or high (excessive)? Check feed intake. A lack of water causes horses to go off-feed within 24 hr. In winter, check water lines for freezing. Evaluate body condition. Inadequate water intake results in weight loss because horses stop eating. Veterinarians can also take blood samples to evaluate the packed cell volume, serum osmolality, and total serum proteins.

Water Quality

Definition: Water quality refers to the suitable and unsuitable characteristics of water that dictate whether it is acceptable for a specific use. For livestock, suitability is based on amounts of total dissolved solids (TDS). Commonly, salinity is a term used to describe TDS. The following characteristics are used to assess water quality: physical, chemical and biological.

Physical criteria
Turbidity assesses water clarity but is a seldom used criteria. TDS is the total of all dissolved water components and is the best single criteria of water quality for livestock. The type of ions in the water determines the effect the water will have on the animals drinking it. Sodium chloride is less detrimental than sodium sulphate at the same concentrations. General guidelines for water usage based on TDS are given in table 3.

Table 3. Definition of TDS and water hardness

Term	TDS (mg/L)	Use for horses	Term	Water Hardness (meq/L)
Fresh water	Less 1500	Usable	Soft	Less 1
Brackish	1500 - 5000	Usable	Moderately hard	1 - 3
Saline	5000 - 30,000	Unacceptable	Hard	3 - 6
Sea water	30,000 - 100,000	Unacceptable	Very hard	> 6
Brine	> 100,000	Unacceptable

Odors from sulphates, tannins, manure or rotting vegetation contribute to most water odors and may affect palatability for some animals. This test is not often used for livestock. Color is due to pigment of suspended particles, tannins or iron fixing bacteria. Color does not affect water usability. Water temperature affects palatability. Horses prefer water at temperatures between 2 to 10°C. Warm water promotes the growth of bacteria and certain algae and may not be as satisfying as cool water.

Chemical criteria
Hardness is the total cationic effect of calcium and magnesium in water. Scaling of kettles and poor soap sudsing indicate hardness. The cation effect is intensified by the anion with which it is associated. Carbonates cause scaling. Noncarbonates do not. Water hardness is not significant to animals but can harm equipment such as water heaters. Hardness criteria are given in Table 3.

Conductivity measures the ability of the water to conduct an electrical current. It is correlated to the TDS concentration. Alkalinity measures the extent to which the water neutralizes a strong acidic solution to a pH of 4.5. It is a component of carbonate, bicarbonate and hydroxyl ions. pH measures the hydrogen ion content of water. A pH of 5-9 is acceptable for domestic animals; 6.5-8.5 is acceptable for marine and freshwater lifeforms.

Cations such as calcium, magnesium, sodium arise from mineral deposits. Soil and organic matter contribute to water potassium. Calcium and magnesium cause hardness. Sodium dominates in water in saline lakes. High water sodium can lower water palatability, contribute to dehydration and lower free choice salt intake.

Anions such as bicarbonate, carbonate, sulphate and chloride are the main anions in water. Bicarbonate (carbonate) water is common in E.Africa and western Canada. Carbonate and bicarbonate determine the pH and "alkalinity" of water. Chloride waters occur throughout the world, while sulphate waters occur in North America (W. Canada, Wyoming, Washington, North and South Dakota). Chloride content is used to evaluate usability of wastewater for agricultural purposes. High sulphate water can cause metal corrosion. It may also cause a "salty" taste. Sulphate can bind with cations such as copper and can cause diarrhea in cattle. There is no evidence that high sulphate water affects horses.

Nitrates in water indicate manure or organic matter contamination. Coarse-textured soils release more nitrates than fine-textured soils. Measures of nitrogen (as nitrate, nitrite, ammonia) assess decomposition in wastewater. High nitrate concentrations irritate the gastrointestinal tract and in some animals can impair iodine metabolism and absorption of vitamins A, E and the mineral, phosphorus.

BOD and COD are measures of organic matter contamination. COD is a chemical test that evaluates total organic matter and has a short analytical time. BOD evaluates the amount of oxygen used by bacteria to metabolize the biodegradable components in a sample of water.

Biological criteria
Animal life in water seldom affects water quality for horses except for decaying wildfowl. Substantial growth of plant life may indicate high organic matter concentrations in water. Most protozoa found in water are non-pathogenic e.g. paramecia. An important human pathogenic protozoa is Giardia.

Algae use oxygen in surface water. Blue-green algae (Cyanophyceae) produce a musty, grassy or septic odor and taste in surface water. Other blue-green algae (Microcystis, Anabaena) produce toxins during decomposition. Poisoning mostly occurs in late summer after a period of warm, sunny weather and rapid algal growth. Signs are sudden and include muscle tremor, ataxia, convulsions, difficulty breathing, salivation, cyanosis and recumbency. Animals may become hypersensitive. Bloody diarrhoea can occur. If the animal survives, liver damage results in photosensitization.

Algae blooms can be controlled with copper sulphate or commercial algaecides when algal numbers exceed 500-1000 cells/ml of water. Addition of copper sulphate should not exceed 1 kg/million litres. If the algae are located on one side of the dugout then spot treatment with a copper sulphate spray can be used. Copper treatment can cause release of algal toxins into the water, so access to copper treated water should be delayed for 2 to 7 days after treatment.

Bacteria occur frequently in water and can be pathogenic or non-pathogenic. E. coli is cultured to evaluate human fecal contamination of water sources. However, humans are not the only animals that add E. coli to surface water. Ducks, cows, pigs and sheep cause more fecal contamination daily than humans. Other water-borne pathogens that affect horses include: Shigella, Salmonella, Leptospira, Yersinia, and enteroviruses. Recently, studies have shown that water bowls with a large amount of feed contamination can harbor high levels of E.coli. These observations emphasize the need to place waterers where horses will not foul them and to clean watering bowls contaminated with feed.

The following microbiological criteria are used to determine "safety" for humans: samples must have less than 10 total coliform organisms per 100 mL, not more than 10% of the samples taken in a 30-d period should show the presence of coliform organisms and not more than two consecutive samples from the same site should show the presence of coliform organisms.

Interpretation of Water Analysis for Horses

Few studies have specifically examined water quality for horses. Most recommendations for horses are based on modified guidelines for other animals. Therefore, interpretations of water quality for horses vary from state to state, country to country. A good rule of thumb, however, is use greater constraints on water quality for young and pregnant horses. Most often water quality is a problem to unadapted, stressed and diseased animals. In table 4, descriptions followed by a (?) indicate that the response is described for cattle.

Table 4. Criteria of Water Quality for Horses

Item	Concentration (ppm)	Use for Horses
Total Dissolved Solids (evaluates inorganic ions; best measure of water quality)	< 1500 1500 - 3000 3000 - 4000 4000 - 5000 5000 - 7000 7000 - 10,000 10,000 +	Very good Good Fair Usable May be unacceptable Unacceptable* Toxic
Ignition loss (evaluates organic matter, hardness)	All levels Brackish or "rotten" smelling	Acceptable May be unacceptable
Hardness (Ca, Mg, CO3, SO4, Cl)	< 100 (soft) 100 - 2000 (hard)	Acceptable Acceptable
Alkalinity	< 500 (pH < 8) 500 - 1000 (pH 8-8.5) 1000 - 2500 (pH 9-10) 2500 (pH > 10)	Acceptable Satisfactory Unfit for young? Unacceptable
pH	< 8.5 8.5 - 10 > 10	Acceptable Tolerable Unacceptable
Chloride	< 500 500 - 5000	Acceptable Usable, salt intake?
Sulphate	< 500 500 - 3300 3300 - 5000	Acceptable Laxative-no effect? Diarrhea, voluntary intake of salt mineral
Potassium	< 300 > 300	Acceptable Usable
Calcium	All concentrations	Acceptable
Magnesium	All concentrations	Acceptable
Nitrites	Trace > trace (10 mg/L upper safe limit for horses)	Acceptable Potential hazard
Nitrates	< 100 (upper safe limit) 100 - 300 > 300	Acceptable Unacceptable? Toxic?**
Iron	< 0.3 > 0.3 (promotes iron bacteria)	Acceptable Lowered palatability
Fluoride	< 4 > 4 > 40	Acceptable Discolors teeth Osteomalacia
Conductivity	All levels	Acceptable
* Horses have tolerated water containing up to 14,500 mg/L total salts for 3 months. ** Nitrate poisoning can occur if high nitrate feeds are also consumed.

References

Agriculture and Agri-Food Canada. 1998. Recommended Code of Practice for The Care and Handling of Farm Animals: Horses, AAFC, Ottawa.

Crowell-Davis, S.L., et al. 1987. Feeding and drinking behavior of mares and foals with free access to pasture and water. J. Anim. Sci.

Cymbaluk, N.F.1989. Water balance of horses fed various diets.Eq. Practice. 11: 19

Cymbaluk, N.F. 1990. Cold housing effects on growth and nutrient demand of young horses. J. Anim. Sci. 68: 3152

Freeman, D.A. , Cymbaluk, N.F.., B. Kyle, H. Schott, K. Hinchcliff and S.M. McDonnell. 1998. Health and welfare of stabled PMU mares under various watering methods and turnout schedules. Part 1. Physiology. AAEP Proc.

Hinton, M. 1978. On the watering of horses: A review. Eq. Vet. J. 10: 27

Martin, R.G., N.P. McMeniman and K.F. Dowsett. 1991. Milk intakes of foals sucking mares on pasture. 12th ENPS. pp 77 - 78.

McDonnell, S.M., D. Freeman, N.Cymbaluk, B. Kyle, H. Schott, and K. Hinchcliff 1998. Health and welfare of stabled PMU mares under various watering methods and turnout schedules, Part 2. Behaviour. AAEP Proc.

Meyer, H. 1995. Influence of diet, exercise and water restriction on the gut fill in horses. 14 th ENPS. Calif. p 90.

Webster, J. 1994. Animal Welfare. A Cool Eye Towards Eden. Blackwell Science.

About the Author

Dr. Nadia Cymbaluk grew up on a mixed farm in Alberta. She obtained an Animal Science degree from the University of Alberta, a M.S. in Animal Nutrition from the University of Guelph, a veterinary degree from WCVM plus spent four years examining equine nutritional deficiencies under Dr. Harold Hintz. Nadia is currently the Managing Veterinarian at Linwood Equine Ranch, an equine research centre serving the PMU industry and the horse industry.

This information was presented at, and appears in the Proceedings of, the 1999 Alberta Horse Breeders and Owners Conference.