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Extension > Horse Extension - Research Updates > June 2013

Monday, June 24, 2013

The Effect Of Hay Net Design On Rate and Amount of Forage Consumed By Adult Horses

The objectives of this study were to investigate the effect of hay net design on the rate and amount of forage consumed by adult horses.

Horses have evolved to consume several small forage-based meals throughout the day, often spending ≥16 hours grazing each day. Modern horse management systems alter this behavior by limiting the amount of time horses spend foraging. The objectives of this study, conducted at the University of Minnesota, were to investigate the effect of hay net design on the rate and amount of forage consumed by adult horses.

Eight adult horses in light work, with an average body weight of 513 kg were fed in individual boxstalls. Horses were fed hay off the boxstall floor (control), or from one of three hay nets: large net (LN, 15.2 cm openings), medium net (MN, 4.4 cm openings) and small net (SN, 3.2 cm openings). During data collection periods, horses had access to hay inside the nets for two 4 hour periods: 0700 to 1100 and 1600 to 2000 each day. Throughout the trial, grass hay was fed at 1% BW twice each day. Horses had ad libitum access to water. To determine forage consumption rate, stopwatches were started once horses began eating, and stopped once horses either finished all offered hay, were no longer interested in eating, or the 4 hour time period had expired. All refuse hay was collected and weighed. Total forage consumed was calculated by subtracting amount of refuse from hay offered.

Mean consumption rates were 1.49, 1.33, 1.11 and 0.88 kg/h (SE ± 0.025) for the control, LN, MN and SM, respectively, with all treatments being different from one another. Horses were able to consume all hay from the control and LN during the 4 hour feeding period, but not all horses finished the hay meal when fed from the MN and SN. Mean percentage of offered hay consumed was 95, 95, 89 and 72% for the control, LN, MN and SN, respectively. There was no difference between the control and LN; however, these treatments were different from the MN and SN, which were also different from one another.

These results demonstrate that the MN and SN were effective in decreasing both rate and amount of forage consumed by adult horses.

Preference of Twelve Perennial Grass Pasture Mixtures Under Horse Grazing

To maximize forage use and promote uniform grazing, mixtures containing meadow fescue, Kentucky bluegrass, perennial ryegrass, and timothy should be planted in horse pastures in the North Central U.S.

Perennial grasses are the foundation of horse pastures in the North Central U.S. Horses are selective grazers, and recent research has shown that horses have a strong preference for Kentucky bluegrass, timothy, and meadow fescue. However, horse pastures are rarely planted to a single species. Planting mixtures is common; however, mixtures are rarely evaluated under horse grazing. The objective of this research, conducted at the University of Minnesota, was to evaluate horse preference of perennial grass pasture mixtures.

Research was conducted in 2011 and 2012 in MN. Four adult horses grazed eight commercially marketed and four experimental perennial grass pasture mixtures. Mixtures contained four to six of the follow species; orchardgrass, reed canarygrass, meadow fescue, Kentucky bluegrass, perennial ryegrass, smooth bromegrass, meadow bromegrass, timothy or festulolium. Individual plots were 1.8 x 6.0 m, and horses were given access to the entire plot area (37 x 22 m). Grazing was initiated when most grasses averaged 20 cm. Horses were allowed to graze the area for 5 days, averaging 4 hours of grazing each day. This grazing length was selected to achieve a minimum average residual height of 9 cm to avoid overgrazing. After grazing, manure was removed, plots were mowed to 9 cm and allowed to regrow. Horses were given ad libitum access to water, housed in a dry lot, and fed grass-alfalfa hay when not grazing. Immediately after grazing, plots were visually assessed for percent of available forage removal on a scale of 0 (no grazing activity) to 100 (100% of existing vegetation grazed to a 9 cm height) to determine horse preference.

Horses showed distinct preferences among the mixtures. Mixtures that included meadow fescue, Kentucky bluegrass, perennial ryegrass, and timothy were the most preferred with ≥86% of the forage removed by horse grazing. Deviating from this combination reduced horse preference. Simply adding orchardgrass to the most preferred mixtures reduced horse preference to 71%. Removing meadow fescue or Kentucky bluegrass and timothy from the most preferred mixtures and adding meadow bromegrass and/or orchardgrass resulted in the least preferred mixtures with a preference of 55%. This agrees with previous research that showed horses did not prefer orchardgrass or meadow bromegrass.

To maximize forage use and promote uniform grazing, mixtures containing meadow fescue, Kentucky bluegrass, perennial ryegrass, and timothy should be planted in horse pastures in the North Central U.S.

Authors: KL Martinson and CC Sheaffer

The Interaction of Grazing Muzzle Use and Grass Species on Forage Intake Of Horses: A Preliminary Study

Preliminary results suggest that the effectiveness of grazing muzzles in reducing herbage mass intake depends on the grass being grazed.

Excessive pasture intakes have been linked to the increase in incidence of equine obesity. Previous research with grazing ponies showed that grazing muzzles reduced pasture intake by 83%. However, horses are selective grazers, and forage grasses have different growth morphologies (i.e. upright and prostrate). Both of these factors could impact the effectiveness of grazing muzzles; however, this has not been researched. The objective of this experiment, conducted at the University of Minnesota, was to determine the effectiveness of grazing muzzles at reducing forage intake when horses were allowed access to different grass species.

Four adult horses, with a mean body weight of 460 kg were grazed in. Prior to grazing, horses were acclimated to wearing the grazing muzzle (Weaver, Mt. Hope, OH) and to grazing for the prescribed amount of time. Four species of perennial, cool-season grasses were grazed, including Kentucky bluegrass, meadow fescue, perennial ryegrass, and reed canarygrass. Kentucky bluegrass and meadow fescue were previously determined to be preferred by horses, while perennial ryegrass and reed canarygrass were less preferred. Kentucky bluegrass and perennial ryegrass have prostate growth habits, while meadow fescue and reed canarygrass have upright growth habits.

Horses were grazed in June and August of 2012 in St. Paul, MN. Horses were allowed to graze a small pasture (4.5 x 9.9m) for 4 hour each day for 4 consecutive days each month. On days 1 and 2, horses were given access to one grass species either with or without a grazing muzzle. On days 3 and 4, horse were given access to a different grass species either with or without a grazing muzzle. Prior to each grazing event, a 0.9 x 3.3 m strip was mechanically harvested from the pasture to determine available initial herbage mass. Post grazing, an adjacent 0.9 x 3.3 m strip was harvested to determine residual forage mass. The difference (on a dry matter basis) was used to estimate horse pasture intake. After grazing, manure was removed and pastures were mowed and allowed to re-grow.

Grazing muzzles decreased the amount of herbage mass consumed by 45, 38, 30, and 4% when horses grazed perennial ryegrass, Kentucky bluegrass, meadow fescue, and reed canarygrass, respectively. The combination of prostrate growth and low preference resulted in the greatest reduction in forage mass consumed when muzzled horses grazed perennial ryegrass. Although reed canarygrass had an upright growth habit, low horse preference resulted in a minimal reduction of forage mass consumed when grazed by muzzled horses.

These preliminary results suggest that the effectiveness of grazing muzzles in reducing herbage mass intake depends on the grass being grazed. This study will be continued in 2013.

Authors: EC Glunk, CC Sheaffer, MR Hathaway, and KL Martinson

Horse Prices and Seller Reasons from Sale Barns in Minnesota, Wisconsin and Texas

Research revealed that horse sale prices varied by location; however, economics were identified as the main reason for selling across all three locations.

The problem of unwanted horses in the U.S. has increased over the past several years. The general decline in the economy and increased cost of feed were recently identified as significant contributors to the unwanted horse problem. Anecdotal claims of horses being abandoned at sales barns also exist but have not been confirmed. The goals of this research, conducted by the University of Minnesota and Texas A & M University, were to document the prices of horses passing through sale barns and identify reasons consigners were selling the horse(s).

Horse sale barns in Minnesota, Wisconsin, and Texas were each visited 6, 5 and 5 times, respectively, from March 2012 to January 2013. Horse sale price, breed, age, and gender were collected, and consignees were asked to complete a short survey identifying the reason for selling. Reasons for selling were placed into four general categories: economics, failure to meet expectations, owner-related issues, and business was horse training/trading.

The average sale price of 512 horses sold at a Minnesota sale barn was $350 and ranged from $1,950 to free. The majority (29%) of horses sold were American Quarter Horses. The average sale price of 605 horses sold at a Texas sale barn was $698 and ranged from $4,800 to $10. The majority (41%) of these horses were American Quarter Horses. The average sale price of 845 horses sold at a Wisconsin sale barn was $916 and ranged from $5,500 to $10. The majority (64%) of horses sold were Standardbreds. Most of the Standardbreds sold at the Wisconsin sale barn originated from harness racing tracks and were sold to the Amish and Mennonite community as buggy horses.

Of all horses consigned (n=2,125), 6% were not sold due to failure of meeting a minimum price. During this time period, no horses were abandoned at the sale barns. Two-hundred seventeen consigner surveys were collected. Forty-one percent of consignees listed economic reasons (i.e. cost of feed, too many horses), 25% cited issues related to the owner (i.e. lost interest, illness), 18% were horse traders, and 16% indicated the horse failed to meet expectations as the primary reason for selling. Some consignees (n=83) had attempted to sell the horse privately, most commonly via the internet, and most sellers (93%) indicated they owned at least one additional horse.

This research revealed that horse sale prices varied by location; however, economics were identified as the main reason for selling across all three locations. This information will be used to develop educational efforts aimed at prospective horse owners, including costs of horse ownership and proper matching of horse and owner.

Authors: WJ Weber, SK Beeson2, J Wilson, DH Sigler, EC Glunk, JL Zoller, and KL Martinson

Investigating The Unwanted Horse Problem in Minnesota, Wisconsin, and Texas

Data indicates that early detection and intervention with humane cases and education focusing on the costs and responsibilities associated with horse ownership are key steps toward addressing the issue of unwanted horses.

The recent increase in the number of unwanted horses in the U.S. has gained national attention. Before education efforts can be developed and targeted, a better understanding of the scope and costs of the unwanted horse problem is necessary.

The goal of this project, conducted at the University of Minnesota and Texas A & M University, was to document factors and costs associated with unwanted horses in Minnesota, Wisconsin and Texas. From March through August 2012, the Minnesota Animal Humane Society (MN AHS) collected data on equine-related humane investigations, including live horses involved, carcasses found on-site, horses seized, other animals found on site and mileage associated with the investigations. Between March and May 2012, a Minnesota renderer collected data on number of horses rendered, breed, age, manner of and reason for death, and cost of rendering. From March through August 2012, four equine rescues located in Minnesota (n=2), Wisconsin (n=1), and Texas (n=1), collected data on number of horses rescued, adopted out, and euthanized, as well as costs associated with these horses. The rescues also provided a summary of fundraising and marketing efforts. Data collection continued through February 2013.

The MN AHS investigated 53 properties, involving 349 live horses. Of the live horses investigated, 28 were seized. The investigations uncovered 2 equine and 1 bovine carcasses, and other animals present on the properties included dogs, cats, llamas, donkeys, poultry, small ruminants, and cattle. Humane agents logged 4,297 miles investigating these cases at a cost of $2,389 (federal reimbursement rate of $0.556/mile).

The renderer picked up 37 equine carcasses. The average age of rendered horses was 18 years, and the dominant breed was the Quarter Horse (n=20). A majority of the horses were chemically euthanized (n=32), and injury and advanced age of the horse were the two most common reason given for euthanasia; however, this information was not always available. Two horses were euthanized due to being unwanted. The average cost of rendering was $168 per horse.

Combined, the four rescues took in 89 horses, of which 7 were returned from previous adoptions. Ten of these were euthanized. Of the remaining horses (n=79), 21 were placed into foster homes, 35 were adopted, 3 were transferred to another rescue; the rest were kept onsite. The average cost for euthanasia was $237; however, some rescues received discounts from veterinarians. On average, rescues invested $285 per horse in veterinary and shipping costs. Rescues listed a number of methods to raise funds and improve adoptability of horses, including trainers' challenges, social media, and newspaper stories.

This data indicates that early detection and intervention with humane cases and education focusing on the costs and responsibilities associated with horse ownership are key steps toward addressing the issue of unwanted horses.

SK Beeson, WJ Weber, JH Wilson, DH Sigler, EC Glunk, and KL Martinson

The Effect of Steaming on Dust Concentrations in Hay

Results indicate that steaming represents a viable management strategy for reducing dustiness in hay containing elevated dust levels.

New management strategies for feeding horses with respiratory disease include steaming hay prior to feeding to reduce dustiness; however, little is known about the effectiveness of this practice.
The objective of this study, conducted at the University of Minnesota, was to determine the effect of steaming on dust concentrations in hay. Dust levels of two alfalfa-orchardgrass hays (low mold [LM] and moderately moldy [MM]) were measured pre- and post-steaming using a commercial hay steamer (The Professional Hay Steamer; Happy Horse Products, Ltd., Palmyra, VA). Prior to steaming for 90 minutes, one flake (1.70 ± 0.23 kg, DM) was removed from the center of each bale (control or non-steamed flake), and the remaining hay was re-tied. Dust content of the control flake was measured while the bale was steamed. After steaming, one flake of steamed hay (1.56 ± 0.34 kg, DM), was removed from the center of the bale, and dust content was measured. To measure dust, each flake was placed inside the drum of an electric cement mixer with two lead weights (3.0 kg) to encourage agitation of the hay. The cement mixer operated at 20 rpm, and total suspended particulate (TSP) levels were measured at the mouth of the drum using a tapered element oscillating microbalance sampler (1400a; Thermo Fisher Scientific, Waltham MA). Instantaneous TSP concentrations were recorded every 60 sec for 30 min. Measurements were averaged over 30 minutes; and the average expressed on a weight (kg) basis.

Initial dust content measurements were different between the two hays; 758 and 406 µg/m3 per kg DM for MM and LM, respectively. Steaming reduced the dust content of the MM hay to 345 µg/m3 per kg DM; however, dust content in the LM hay was not significantly affected by steaming (257 µg/m3 per kg DM).

Limited data is available regarding typical, or acceptable, concentrations of dust in feedstuffs commonly fed to horses. However, steaming of the MM hay reduced dustiness to levels comparable to the LM hay, which was considered an acceptable hay for horses. Additional research needs to determine acceptable levels of dust; until then, results from this study indicate that steaming represents a viable management strategy for reducing dustiness in hay containing elevated dust levels.

Authors: JE Earing, CC Sheaffer, BP Hetchler, LD Jacobson, JC Paulson, MR Hathaway and KL Martinson

Pasture Best Management Practices on Horse Farms in MN and WI

Data suggests that farm owners are aware of some recommended pasture best management practices for horse farms, but practices are not fully or consistently implemented.

A well-managed horse pasture can reduce environmental impacts from erosion and runoff and can promote overall horse health by providing constant access to forage. The objective of this project, conducted at the University of Minnesota, was to determine what pasture best management practices (BMPs) were being used on horse farms in Minnesota and Wisconsin.

Data was collected from 26 horse farms that were enrolled in the University of Minnesota Pasture Management Program. Best management practices evaluated at each farm included the use of a sacrifice lot, rotational grazing use, percent ground cover, soil nutrient management, weed control, and manure storage.

Of the 26 enrolled farms, 22 were used for personal recreation, two for therapeutic riding facilities, and two were boarding facilities. Five farms had been purchased recently and had no existing pasture or horses on site; these farms were not included in the summary of data.

Of farms with existing pastures (n=21), the average number of acres allocated to pasture was 10. The average number of horses per farm was 5, resulting in a stocking density of 2 acres per horse. Seventeen farms had designated sacrifice lots. The average pasture ground cover was 88% with Kentucky bluegrass, smooth bromegrass and reed canarygrass being the predominant grasses. Three farms had used herbicide for weed control in the last three years; however, none of the farms utilized mowing as a weed control strategy. Fourteen pastures contained weeds listed as noxious weeds with Canada thistle being most prevalent, and two pastures contained plants poisonous to horses. Six farms used some form of rotational grazing, and 10 farms exhibited signs of overgrazing. Nine farms stockpiled their manure, while 7 farms had no manure management plan and essentially did "nothing" with their manure. Only 2 farms were aware of manure storage regulations. Running water (i.e. streams) or wetlands were found in, or adjacent to, pastures on 9 farms. Only 1 farm had soil sampled and fertilized previously, and soil analysis indicated that fertilization for at least one of the three primary macronutrients (nitrogen, phosphorus, potassium) was necessary on all farms.

This data suggests that farm owners are aware of some recommended pasture BMPs for horse farms, but practices are not fully or consistently implemented.

Authors: SL Privatsky, JE Earing, JA Lamb, CC Sheaffer and KL Martinson

Foal Weight Gain on Pasture

A positive relationship was identified between foal average daily gain (ADG) and rainfall, suggesting ADG's will be higher during periods of greater rainfall.

Researchers from the University of Kentucky have shown that pasture growing conditions can influence average daily gain (ADG) in foals.

A group of 320 Thoroughbred foals were regularly weighed between birth and weaning. Estimates of ADG were calculated for all foals at 3 or 4 months of age in May, June, July, and August. During these months, foals (and mares) were kept on predominantly cool-season grass pastures. Information on daily rainfall was also collected.

A positive relationship was identified between ADG and rainfall, suggesting ADG's will be higher during periods of greater rainfall. Results showed that ADG was within or above suggested ranges during May, but below ranges during June, July, and August. Higher rainfall, paired with the cooler temperatures of May likely increased pasture growth, nutrient availability, and subsequent foal ADG. However, in later summer months, ADG was below expected rates, suggesting supplementation may be necessary when pasture growth is depressed due to weather conditions.

Summarized by: Jennifer Earing, PhD, Univ. of Minn.

Thursday, June 6, 2013

Social Separation and Training

There were no significant differences between singly trained mare and mares trained in pairs.

The intensity with which a horse responds to separation from its group and subsequently to being alone is relevant for both horse and handler safety. Identification of training methods that may reduce responses to separation would be useful in practice. The objective of this research, conducted at the Swedish University of Agricultural Science, was to investigate whether the initial presence of a familiar companion horse modifies responses to separation from the group, lowers stress levels (as measured by heart rate) and increases training efficiency. Researchers hypothesized that habituation to separation proceeds more quickly if the horse is first trained with a companion, and heart rate is lower when the horse is subsequently trained alone, compared to control horses trained individually from the start.

Young mares, kept in groups of 4, were exposed to social separation: 2 horses of the group were trained singly and the remaining 2 horses were trained first with a companion and then alone. The training comprised of three steps whereby distance from the group was gradually increased. The final learning criterion was met when a horse fed calmly alone inside a test arena. Horses that were trained in a pair had to succeed in the final learning criterion (feeding calmly alone inside a test arena) together before they repeated the steps alone. Feeding behavior and heart rate were recorded.

There were no significant differences between singly trained mare and mares trained in pairs, indicating that the initial pair-training did not reduce stress responses in pair trained horses. However, heart rate was significantly lower when horses were trained in pairs compared to when the same horses were subsequently trained alone.

It may not be efficient to habituate naïve young horses to social separation initially with a partner as these horses appear to have to relearn being in the test situation alone when switching to the individual training method.

Summarized by Krishona Martinson, PhD, Univ. of Minn.
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