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Extension > Horse Extension - Research Updates > April 2013

Tuesday, April 30, 2013

Adding Supplements to Water

Adding supplements or electrolytes to water can decrease intake in horses.

A 1,000 pound horse should drink about 8 to 10 gallons of water each day. In order to encourage horses to drink, especially when away from home, owners frequently "flavor" (i.e. peppermint) their water; however sometimes electrolytes or supplements are added, which are different than flavors. The objective of this study, conducted by Land O'Lakes Purina, was to test the hypothesis that horses decrease water intake when supplements or electrolytes are added to water.

Six mature horses were offered both plain water and water with one of 4 different supplements. Additives included 2 electrolyte preparations (Farnam Apple Dex and Land O'Lakes Calf electrolyte), a vitamin/mineral (Farnam Red Cell) additive, and a joint additive (Finish Line Fluid Action). All additives were offered at a rate of 28 g per 5 gallons of water. Water intake from buckets was recorded via weight and replenished at 7:00 am and 6:00 pm each day. Horses were fed the same diets, had unlimited access salt, and were housed individually.

There was an effect of adding supplements and electrolytes to water as horses preferred plain water with a mean daily intake of 3 gallons versus 1 gallon for supplement or electrolyte water; horses drank over twice the amount of plain water compared to supplement or electrolyte water. There was no difference within the additive treatments for water intake. There was a trend for water intake to be affected by time of day, with the greatest volume consumed overnight. This trend may have been influenced by timing of water weighing and replenishment, and/or housing management conditions.
Adding supplements or electrolytes to water can decrease intake in horses. This may lead to dehydration, poor performance or other adverse health effects in horses. If planning to add supplements or electrolytes, acclimate the horse before traveling or placing the horse in a stressful condition.

Summarized by Krishona Martinson, PhD, University of Minnesota

Thursday, April 4, 2013

Microchip Identification

The objectives of a study conducted at Pennsylvania State University were to characterize the inflammatory response after microchip insertion, evaluate pain response and swelling at the microchip insertion site, and measure migration of the microchips.

The inflammatory process during insertion and occurrence of migration are major concerns of horse owners when determining the usefulness of microchip identification. The objectives of a study conducted at Pennsylvania State University were to characterize the inflammatory response after microchip insertion, evaluate pain response and swelling at the microchip insertion site, and measure migration of the microchips.


Eighteen mature Quarter Horse mares were assigned randomly to three treatment groups. The microchip group (n = 7) had microchips inserted using a sterile needle and syringe; the "sham" group (n = 7) had a needle inserted but no microchip; and the control group (n = 4) had no insertion. The insertion site was visually determined by a veterinarian to be within the nuchal ligament on the left side of the horse, with a transverse position halfway between withers and poll, and dorsal position several centimeters below the crest of the neck.


The inflammatory response was measured over a 2-week period by measuring dermal temperature, response to pressure and swelling at the insertion site, and plasma serum amyloid A (SAA). SAA is expressed in response to inflammatory stimuli.
For the migration component of the study, radiographs of the seven microchipped horses were taken over 6 months after insertion. These radiographs allowed measurement between a select vertebral point and the microchip.


The microchip and sham insertion did not cause a detectable increase in temperature. Algometer readings, used to quantify pressure necessary to induce a pain threshold response, indicated that microchip insertion area was more sensitive than sham insertion at 2 hours on day 1, and day 3 post insertion. Visible swelling began 2 hours post-insertion and resolved by day 3. SAA concentrations were affected by day following insertion, but not by treatment group. Increases in SAA concentration could not be matched with local insertion reactions. Migration was not detected in any of the horses during the 6 months.
Microchip identification is a viable alternative form of identification for equids. It does not cause excessive inflammation or continued tissue irritation after insertion. It also does not migrate if implanted within the nuchal ligament on the left side of the horse halfway between the withers and poll.


However, it may be important to continue to assess the microchips for migration in young growing animals. For some breed registries, identification has to be obtained on registration, so microchip insertion will have to be performed at less than 1 year of age. Although the microchip may not actually be moving, the development of the tissues around the microchip could put it in a different position than anticipated. Future studies should investigate ideal location as affected by age for microchip insertion.


Summarized by Krishona Martinson, PhD, University of Minnesota


Monday, April 1, 2013

Grazing Muzzles

Grazing muzzles are an effective means of restricting pasture intake by ponies.

Grazing muzzles can be used to reduce pasture intake and are alternatives to isolating horses in dry lots and stalls. There is limited information on the extent of intake restriction imposed by grazing muzzles. Therefore the objective of this study, conducted by researcher in England, was to quantify the effect of wearing a grazing muzzle on forage intake by ponies.

Four mature ponies were used for this study. Pasture intakes were measured on four, 3 hour occasions per pony when fitted with a muzzle or grazing without a muzzle. Pasture intake was determined by change in body weight after grazing.

Pasture intakes were significantly reduced when ponies were fitted with a grazing muzzle. Ponies averaged 1 pound of forage per 3 hours with grazing muzzles compared to 7 pounds of forage per 3 hours without a muzzle, representing a 83% reduction in pasture intake for ponies wearing grazing muzzles compared to those without. Pasture dry matter intake by ponies without grazing muzzles averaged 0.8% body weight during the 3 hours, which is equivalent to one half to two-thirds of the recommended daily energy requirement.

This evidence suggests that grazing muzzles are an effective means of restricting pasture intake by ponies.

Summarized by Beth Allen, University of Minnesota

Hay Steaming

Steaming represents a management strategy for reducing dust and mold levels and increasing dry matter intake in some hays. However, steaming should not replace the main goal of feeding good quality (i.e. low in dust and mold) hay.

Management strategies for horses with respiratory disease include soaking hay prior to feeding. Hay steaming is an alternative to this practice; however, little is known about its impact on forage nutritive values or intake. The objective of a study recently conducted at the University of Minnesota was to determine the effect of steaming on forage quality and intake by horses.

Two alfalfa orchardgrass mixed hays were evaluated: a low and moderately moldy hay. Each day, one bale of each hay was steamed for 90 minutes using a commercial hay steamer (Happy Horse Products). Two flakes of steamed or un-steamed low or moderately moldy hay were offered simultaneously to six adult horses in individual hay nets (thee horses per treatment). Horses were fed for 5 days and then switched hay types for 5 additional days. Horses were allowed access to hay for 2 hours and dry matter intake was calculated. Flakes of un-steamed or steamed hay were also agitated in an electric cement mixer, and dust concentrations were recorded every min for 30 minutes using a tapered element oscillating microbalance (TEOM) sampler.

Steaming increased hay moisture and therefore reduced dry matter to 77 and 71% for low and moderately moldy hay, respectively. In both low and moderately moldy hay, steaming reduced phosphorus content. Steaming reduced water soluble and ethanol soluble carbohydrate content by 13% and 27%, respectively, for moderately moldy hay, but had no effect on low mold hay. Steaming reduced mold levels in both hays. Dust concentrations of moderately moldy hay were reduced by 55%; however, dust levels in low mold hay were not affected by steaming . Dry matter intake of low mold hay was increased by steaming; however, dry matter intake of moderately moldy hay was not affected by steaming.

For hay with low mold levels, steaming decreased mold levels, increased dry matter intake of the hay, but had no effect on dust level. In moderately moldy hay, steaming reduced mold and dust levels, but did not improve dry matter intake. Steaming represents a management strategy for reducing dust and mold levels and increasing dry matter intake in some hays. However, steaming should not replace the main goal of feeding good quality (i.e. low in dust and mold) hay.

Co-authors: J. Earing, PhD, M. Hathaway, PhD, C. Sheaffer, PhD, B. Hetchler, L. Jacobson, PhD, and J. Paulson, University of Minnesota and Tennessee Farmers Cooperative.





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