Original ResearchThe Effect of Steaming and Soaking on the Respirable Particle, Bacteria, Mould, and Nutrient Content in Hay for Horses
Introduction
Grass hay is the most common fodder fed to stabled horses in the UK [1] and United States [2]. The nutrient content of both seed hay (monospecies) and meadow hay (multispecies) is mainly determined by the grass mixture and stage of growth at harvest, whereas the hygienic quality is more influenced by weather during the conservation process and storage conditions [3]. Feeding long forage to stabled horses can help maintain normal time budgets by satisfying the animal's innate need to chew [4]. Good hay or haylage can also supply a significant proportion of the daily nutrient requirements, although many owners find haylage too energy dense to be offered ad libitum and thus prefer to feed their horses a higher fiber lower energy forage such as grass hay.
Traditionally, farmers and horse owners assess hay visually and by smell; however, even well conserved hay can contain significant levels of respirable dust, and therefore, visual assessment is not a recommended method for selecting hygienic hay [5]. Respirable dust is composed of particles less than 5 μm in size and is referred by Hessel et al [6] as the thoracic fraction and by Art et al [7] and Clements and Pirie [8] as particles that are sufficiently small (0.5–5 μm) to penetrate the peripheral airways. Respirable dust contains potentially allergenic particles, such as mould and bacteria spores, mite feces, endotoxins, and beta glucans, all of which have the potential to contribute to the etiopathogenesis of equine environmental airway diseases including recurrent airway obstruction (RAO) in stabled horses [9], [10]. Although administration of corticosteroids and bronchodilators can alleviate the symptoms of RAO, these drugs contravene competition rules, and long-term use is expensive. Maintaining an RAO horse in an asymptomatic condition is best done by reducing the dust/animal interaction [11], [12], [13]. Woods et al [14] and Moore-Colyer and Auger [15] demonstrated that during feeding, dust in the breathing zone of the horse can be significantly higher than in the general stable environment thus minimizing dust released from feed is paramount. To reduce the dust released from hay fodder, many owners soak or steam their hay before feeding [16].
Soaking reduces the number of airborne respirable particles (ARPs) but has undesirable consequences as it leaches valuable minerals [17], [18] and water-soluble carbohydrates (WSCs) [19] from the hay, increases bacterial concentrations by 1.5-fold to fivefold [20], [21], and can produce postsoak liquor with a very high biological oxygen demand [22]. Poor forage hygiene derived from bacterial and mould proliferation has been associated with colic in horses [23]; thus, reducing the quality of forage by soaking is highly undesirable.
Steaming hay is rapidly becoming an acceptable alternative to soaking. Blackman and Moore-Colyer [18] reported that steaming hay for 80 minutes in 5-kg hay nets in a plastic dustbin fitted with a kettle element in the bottom, reduced ARP by 95% while conserving the mineral content of the hay. However, the impact of steaming in a dustbin on the bacterial and mould concentrations in the hay has not been established. Steaming using the specifically designed hay steamers such as the Haygain1000 (HG 1000) and HG 600 (Propress Equine Ltd, Hungerford, UK) has been shown to reduce ARP and microbiota in hay [20], [24], [25], but to date, there is no published information on the effect of high-temperature steaming on the nutrient content of hay.
The objective of the experiment 1a was to determine the effect of soaking and three different steaming techniques on the ARP numbers. In experiment 1b, the objective was to measure the effect of two different steaming techniques on the bacteria and mould content in hay, whereas experiment 2 determined the effect of high-temperature steaming on the nutrient content of hay for horses.
Section snippets
Experiment 1a
Eight square bales of field-dried UK meadow hay conserved in 2011 weighing approximately 25 kg were subjected to five different wetting treatments. Each bale was divided into five equal sections of approximately 5 kg and placed into small-holed (50 mm) hay nets. Before the steaming treatment took place, three wooden rulers containing nonreversible temperature strips (555-409, RoHS Scale B Self-adhesive, testo, www.testo.com) were pushed firmly into three different areas of the hay so that steam
Results
Hays used in all experiments were either meadow hay conserved from permanent pasture and contained a range of different grass species or seed hay which was all single species perennial rye grass (Lolium perenne). Hays were collected from across the UK and were thus a cross-section in terms of hygienic quality and nutrient content from the 2009 hay-making season.
Discussion
Across all the treatments examined, the results showed that steaming a range of hays in a high-temperature hay steamer conserved mineral and CP contents while being the most effective method for reducing ARP and viable microbial numbers.
Conclusions
The results of the present study show that when comparing dry, soaked, partially steamed, and high-temperature steaming, the most effective method for reducing ARPs, while conserving nutrients and improving the hygienic quality of hay fodder, is best achieved using the Haygain specifically designed high-temperature steamers. The present studies also show that partial steaming and soaking while effective at reducing ARPs in hay are contraindicated in terms of microbial contamination, and thus,
Acknowledgments
The authors thank Haygain Ltd for the use of the HG 1000 and HG 600 steamers for this work. There are no conflicts of interest for any of the authors.
References (47)
- et al.
Generation of airborne particles from horse feeds depending on processing and type
J Equine Vet Sci
(2009) - et al.
Respirable dust concentrations in equine stables. Part 1: validation of equipment and effect of various management systems
Res Vet Sci
(2007) - et al.
The loss of water soluble carbohydrate and soluble protein from nine different hays soaked in water for up to 16 hours
J Equine Vet Sci
(2009) - et al.
A modified simple solution method for the determination of phosphate in natural waters
Anal Chem Acta
(1962) - et al.
Effect of agriculture and environmental factors on the hay characteristics involved in equine respiratory disease
Agric Ecosyst Environ
(2010) - et al.
Effect of forage conservation method on microbial flora and fermentation pattern in forage and in equine colon and faeces
Liv Sci
(2008) - et al.
Growth, training response and health in Standardbred yearlings fed a forage-only diet
Animal
(2013) A survey of forage feeding practices in the UK
(2012)Feeding and care of the horse
(2005)- et al.
The effect of soaking on water soluble carbohydrate and protein content of hay
Vet Rec
(2011)
Biological basis of behaviour and feed intake
Techniques for assessing respiratory health hazards from hay and other source materials
Equine Vet J
Environmental control of respiratory disease
Management of heaves
Equine Vet Educ
Recurrent airway obstruction: a review
Equine Vet J
Randomized controlled study of inhaled fluticasone propionate, oral administration of prednisone and environmental management of horses with recurrent airway obstruction
Am J Vet Res
Evaluation of intradermal mould and antigen testing in the diagnosis of equine chronic obstructive pulmonary disease
Equine Vet J
Feeding and bedding materials as sources of microbial exposure on dairy farms
Scand J Work Environ Health
Airborne dust and aeroallergen concentration in a horse stable under two different management regimes
Eq Vet J
Airway mucous in recurrent airway obstruction and short term response to environmental challenge
J Vet Intern Med
The effects of soaking hay fodder for horses on dust and mineral content
Anim Sci
Hay for horses: the effects of three different wetting treatments on dust and mineral content
Anim Sci
Cited by (22)
Nutritional Considerations When Dealing with an Obese Adult Equine
2021, Veterinary Clinics of North America - Equine PracticeSteaming Conditions Enhance Hygienic Quality of the Compromised Equine Hay With Minimal Losses of Nonfiber Carbohydrates
2019, Journal of Equine Veterinary ScienceCitation Excerpt :In accordance with Earing et al [11], steaming of hay with appropriate hygienic quality showed no effects on forage nutritive values, except a decreasing effect on specific minerals. Regardless of hay quality, no effect on CP and fiber content was observed, which was also observed by Earing et al [11] and Moore-Colyer et al [10,13]. However, inconsistent effects of soaking on CP contents have been reported previously [9,13,24].
Effects of Watering/Steaming of Large Square Hay Bales on Particulate Matter Generation
2018, Journal of Equine Veterinary ScienceCitation Excerpt :To sum up, the procedure of watering and subsequent steaming led to a mean decrease in bacterial concentration (49.70%/g DM hay) and mold concentration (34.53%/g DM hay) in the present study. An increase in the bacterial concentration, as was recorded after soaking (dry: 60,256 CFU/g DM hay vs. soaked: 354,813 CFU/g DM hay and dry: 21,800,000 CFU/g DM hay vs. soaked: 37,200,000 CFU/g DM hay) [6,17] or the inhomogeneous steaming of hay in a wheelie bin (dry: 234,422 CFU/g DM hay vs. wheelie bin: 549,540 CFU/g DM hay) [12], could not be determined in the present study. However, the mold reduction (34.53%/g DM hay) achieved after the bale treatment (watering/steaming) was much lower than that achieved after the treatment of hay in British hay steamers or in the wheelie bin.
Particulate Matter in Equestrian Stables and Riding Arenas
2017, Journal of Equine Veterinary ScienceThe Effect of Management Regime on Airborne Respirable Dust Concentrations in Two Different Types of Horse Stable Design
2017, Journal of Equine Veterinary Science