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Advantages and Challenges of Haylage

Advantages and Challenges of Haylage

By Professor Meriel Moore-Colyer, Dean of the School of Equine Management and Science at the Royal Agricultural College.

(This follows on from Meriel’s previous article on the different types of haylage.)

With the problems farmers face in UK making good quality hay, haylage is often a safer bet as it can be made and wrapped within 2 days, generally resulting in cleaner nutritious forage. However, it is a mistake to believe that haylage is bacteria and mould free.

In fact haylage can contain significant quantities of the fungi P. roqueforti. Haylage is also NOT dust free as Table 2 shows. Haylage can contain high levels of pollen (Seguin et al., 2010) and recent work presented at WEAS 2017 has shown that horses with Equine Asthma are allergic to a range of pollens, bacteria and fungi (White et al., 2017). 

Table 2. Airborne respirable dust in different types of forage


Average respirable particles /litre air (+/-SD)

Good hay

63000 (+/- 30000)

Late-cut haylage (87%DM)

8800 (+/- 2500)

Early-cut haylage (50%DM)

4500 (+/- 1900)

                                                                                                                           Source: (Vanderput et al. 1997)

In early cut haylage the production of lactic acid preserves the forage and if the pH is between 4 and 5 the shelf life in winter can be 5 days, dropping to 3 in summer.

With late cut haylage less sugar is in the crop when cut so the lactobacilli bacteria have nothing to turn into lactic acid. This means the pH is higher at 5.6 to 6 so once opened, aerobic spoilage occurs sooner, dropping the shelf life to 2 days in the summer. Aerobic spoilage can include growth of the highly undesirable Clostridia botulinum species which occurs in high pH haylage and can be a particular risk in large round bales.

Although early cut haylage is more nutrient dense and potentially ‘cleaner’, it is quite acidic. This poses challenges to dental health as detailed by Gere and Dixon, (2010) who found increased incidence of dental cares in horses fed haylage and concentrates compared with those fed hay and concentrates.

The more nutrient dense haylage is also easy to over feed, so to avoid horses getting fat owners restrict access. This compromises natural foraging behaviour reducing the normal time budget of 16 hours per day feeding. Compromising feed intake and the natural trickle feeding behaviour can have negative effects on gut health.

Dealing with the challenges of feeding haylage

The quality of haylage can be improved by steaming and indeed the post-steamed forage is palatable, nutritious and clean.

Dangerous bacteria and their by-products such as the C. botulinum toxin is inactivated at temp > 80oC (CDC, 1998) and as the high-temperature steamers made by Haygain reach temperatures in excess of 100oC, risk from botulism is significantly reduced.

It is important that haylage is steamed properly and at high temperatures. To do this you need to use a specifically designed high-temperature steamer such as the range made by Haygain.

These steamers are designed to evenly distribute high temperature steam into all the forage and the specifically designed container allows high temperatures to be maintained for the required time (minimum of 10 minutes) to ensure microbe death, as detailed in Table 3.

Experiments have shown that steaming hay and haylage incompletely at lower temperatures (70-85oC) (Leggatt and Moore-Colyer, 2013) acts as an incubator causing an increase (up to 5-fold) in microbial content, which is highly undesirable. Interestingly, post-steamed haylage has lower bacteria and mould levels 4-days after steaming and is cleaner than freshly opened haylage. This is very useful as steaming haylage will increase shelf-life making haylage a suitable alternative to hay for the 1 or 2- horse owner. Big-bale haylage is more economical to buy and even adding the cost of steaming, it is still cheaper than buying small-bale haylage from the feed merchant. Cost small 20 kg bales = 30p/kg, big 300kg bale = 10p/kg + steaming at 16p/kg = 26p/kg.          

Table 3 Total bacterial counts (TVC) and fungi in fresh haylage, haylage opened for 4 days, freshly steamed haylage and steamed haylage left open for 4 days




Fresh + 4 days


Steamed + 4 days


Fungi /g






Log fungi


















abc Values in the same row not sharing letters differ significantly (P<0.05)



White S1,2, Moore-Colyer M1, Coüetil L3, Hannant D2, Richard E5, Marti E6 and Alcocer M2. (2017) Development of a Multiple Protein Extract Microarray for Profiling Allergen-Specific Immunoglobulin E in Horses with Severe Asthma. World Equine Airway Symposium. Openhagen, Denmark, July 2017.

King L (2012) A survey of forage feeding practices in UK. BSc thesis. Royal Agricultural College, Cirencester Glos. UK

Leggatt, P., and Moore-Colyer, M.J.S (2013) The effect of steam treatment on the bacteria, yeast and mould concentrations in haylage for horses. Proceedings of the British Society of Animal Science. Nottingham UK, April 2013

Seguin V, Lemauviel-Lavent S, Garon D, Bouchart V Gallard Y, et al (2010) Effect of agriculture and environmental factors on the hay characteristics involved in equine respiratory disease. Agric Ecosyst Environ 135: 206–215

Gere, I and Dixon, P.M. (2010) Post moretum survey of peripheral dental caries in 510 Swedish horses. Equine Veterinary Journal 42: 310-315

Vanderput, S., Istasse, L., Nicks, B. and Lekeux, P. (1997) Air borne dust and aeroallergen concentration in different sources of feed and bedding for horses. Vet Q 19: 154-158


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