By Professor Meriel Moore-Colyer, Dean of the School of Equine Management and Science at the Royal Agricultural College.
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
|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 caries in horses fed haylage and concentrates compared with those fed hay and concentrates.
The more nutrient dense haylage is also easy to overfeed, so to avoid horses getting fat owner’s 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). It is important that haylage is steamed properly and at high temperatures.
“Commercial 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.“ Becky James, Director, Technical Sales at Haygain.
A comparison is 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
|CFU||Fresh||Fresh + 4 days||Steamed||Steamed + 4 days||s.e.d|
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