The winner in the carefully controlled study was baleage with a moisture content of 65 per cent, followed by grass which was baled and wrapped when drier (haylage), and then hay.
Le vainqueur de cette étude dûment controlée est le préfané à 65% d'humidité, suivi par le préfané à moindre taux d'humidité.

The research was carried out Dr Cecilia Müller and Dr Peter Udén, of the Department of Animal Nutrition and Management at the Swedish University of Agricultural Science in Uppsala.
L'étude a été menée par une université suédoise à Upsala.

The making of baleage and haylage involves wrapping grass to deprive it of oxygen, resulting in acidification of the forage (ensiling). The baleage was baled when the dry-matter content was 350g/kg (a moisture content of 65%).
Nos amis neo-zelandais ont diverses appellations pour le préfané : baleage=65%, haylage=30..45%. Pour l'étude, deux lots de préfané ont été sélectionnés. Le premier avait 45% de taux d'humidité et le deuxième 30%. Les ballots ont été emballlés dans les deux heures suivant la mise sous presse. Le foin (normal) a été récolté et sêché à 13% d'humidité

For the study, two lots of haylage were made and fed to the horses, each with a different moisture content at the time of baling. The first lot was made at 550g/kg (45 percent moisture content) and the last lot at 700g/kg (30 per cent). All bales were wrapped within two hours of baling.

The hay was baled at 870g/kg (13 per cent moisture content) and placed in a shed drier for nine days.

The researchers gave four horses the four forages once daily during four consecutive five-day experimental periods. Each sample contained 1kg of dry matter of each forage.
Les chercheurs ont donné à 4 chevaux les 4 fourrages une fois par jour durant 4 périodes-test de 5 jours consécutifs. Chaque ration contenait 1Kg de matière sêche pour chaque fourrage.

Balage is an increasingly popular winter feed for horses. It's nutritious and most horses enjoy it, but there are risks. Neil Clarkson reports on strategies to minimise them.
Le préfané devient de plus en plus populaire comme aliment d'hiver pour les chevaux et la plupart de nos équidés aiment cet aliment. Mais il y a des risques. Neil nous explique comment les minimiser
There's nothing like a disastrous hay season to get horse owners thinking about their options. Some think about balage - those big plastic-wrapped bales of grass that dot the countryside in increasing numbers as the summer progresses.
C'est après une mauvaise saison de récolte du foin que les propriétaires pensent à d'autres options. Il y en a  qui pensent de plus en plus au préfané (nos amis français appellent cela l'enrubannage). Il s'agit d'herbe coupée et emballée un certain temps après la coupe pour éviter les risques dûs à la pluie. Les propriétaires sont tentés d'essayer mais se rétractent après un essai infructueux.

While some contractors now offer wrapped small bales, most is made in rounds, or big or medium squares. A horse owner will need to pay a contractor to cart them in. Even if you have a tractor, you will need a special clamp to pick them up without rupturing the plastic.
Bien que certaines entreprises agricoles puissent emballer de petites balles, le conditionnement principal se fait en grosses balles, soit rondes, soit carrées. Mêm si vous disposez d'un tracteur il vous faudra un équipement spécial pour ne pas endommager le plastique.

They can be stored outside, which will appeal to many, but once cut open they must be fed out within a few days. Unless you have a lot of hungry horses, or some cattle on your property, you may not get through a bale before it spoils.
Les ballots peuvent être stockés à l'extérieur, mais une fois ouverts, il doivent être consommés en quelques jours sinon la matière pourrit.

Balage is also more costly, but you have to weigh that against the higher food value when compared to hay.
Le préfané coûte plus cher à cause de l'emballage plastique, mais il faut savoir que le taux en matière sêche est plus élevé que dans le foin.

Like hay, things can go wrong. There are also risks in feeding it to horses - mostly the danger of botulism poisoning, which we will consider later.
Mais il peut y avoir des soucis ou des risques à nourrir les chevaux avec du préfané. Le principal est le botulisme. ON le verra plus loin dans cet article.

What is balage?

Balage, silage, and haylage are names for the same basic product: ensiled grass. It doesn't matter whether the grass is going into a massive silage pit or a plastic-wrapped bale - the process is the same.
The grass is baled when much greener than hay. Hay is typically baled with a moisture content between 15% and 17%. Ensiled grass is typically between 30% and 60%, with the most stable balage usually made in the higher half of that range.
L'herbe est emballée alors qu'elle est encore humide. Le foin est généralement mis en ballots lorsque le taux d'humidité atteint 15 à 17%. Pour le préfané, on parle de 30 à 60% d'humidité. Le meilleur compromis est de l'ordre de 45%.

The grass may only be cut for a day or even less before the balers arrive. Souvent après seulement un jour, la matière est prête à être emballée.

The grass needs to be good quality with a high sugar content. Coarse, stemmy grass will not only make inferior balage, it is also more likely to puncture the plastic wrap.
Il faut que l'herbe soit de bonne qualité avec un taux élevé de sucres. L'herbe de mauvaise qualité ne va pas seulement produire un mauvais préfané mais risque aussi de percer le plastique de protection.

The contractor needs to produce a good tight bale with as little air in it as possible. Loose bales are unlikely to make good balage. (When silage is being made, a digger will trundle backwards and forwards over the grass for hours, compacting the heap as much as possible.)
La société devra produire un ballot compact avec le minimum d'air.

Grass is rowed up in preparation for baling. The best moisture range for making balage is between 40% and 60%, which may take only a day's wilting, even less.   Moisture content is critical Correct moisture content is considered one of the most critical elements in successfully making balage, along with high sugar content. The usual range is 30% to 60% moisture, with the most stable balage usually being made in the higher half of that range. If it's baled much above 60%, conditions tend to swing in favour of the clostridial bacteria. Baling grass that is too dry has its problems, too. A drier bale is likely to undergo too much damaging aerobic activity before anaerobic fermentation begins. It is also less likely to drop below the desired pH of 5.0, giving clostridial bacteria yet another opportunity to multiply.

A well-compacted bale may heat as little as 3degC before it runs out of air. Grass baled when drier is likely to have more air trapped in it, and the heating process can continue too long. Once temperatures of 40degC or more are reached, the grass will suffer heat damage and blacken, sometimes costing more than half the available protein.
Un ballot bien compacté va seulement chauffer de 3°C avant que l'oxygène ne soit épuisé. Si l'herbe est trop sêche, il y aura trop d'air à l'intérieur et le processus va durer trop longtemps et la température va trop s'élever. A plus de 40°C, l'herbe va subir les dommages de la chaleur et noircir et perdre de sa valeur nutritive.

Generally, the quicker this aerobic phase is over, the better, because the goodies you want to feed out to your horses are being used up. Bacteria are turning useful water-soluble sugars into carbon dioxide and water, with heat being a major byproduct.
Généralement, plus vite va le processus aérobique, mieux c'est. Si le processus dure trop longtemps, les sucres solubles se dégradent.

Once the oxygen is gone, this aerobic heating phase will end. However, waiting in the wings are anaerobic bacteria, which function without the need for oxygen. They multiply rapidly and begin to ferment the grass, turning the plant sugars into organic acids - mainly lactic and acetic acid. As this continues, the bale becomes increasingly acidic.
Une fois que l'oxygène a été consommé, cette phase d'échauffement aérobique se termine. Cependant les bactéries anaérobiques n'ont pas besoin d'oxygène et se multiplient rapidement pour faire fermenter l'herbe en transformant les sucres en acides organiques. Le ballot devient acide.

Once it reaches a pH of about 3.8 to 5.0, the anaerobic bacteria find the going too tough and the fermentation process grinds to a halt. The bale has reached a stable state, ready to ride out the months until it is fed out. All should remain well unless the bale is punctured and oxygen penetrates.
Une fois qu'il atteint un pH de 3.5 à 5, le processus s'interrompt. Le ballot a atteint un état stable et peut se conserver durant des mois. Tout se passera bien à moins que le plastique ne soit percé et que l'oxygène ne pénêtre dans le ballot.

Hints for making good balage These measures will not only improve balage quality, but reduce the risk of spoilage.   Using quality grass with a high sugar content increases the chances of making good balage.     Use grass before it's too mature and stalky. Younger grass will make much better balage. Poor quality grass will always make poor quality balage.   Cut the grass later in the day, when the sugar content will be higher.   Cut only when you're confident you can get it baled and wrapped before it rains.   If your cut grass does get rained on, tell the contractor to use an additive which will help the fermentation.   Do what some farmers do: pay extra to have inoculant applied every time you make balage.   Wrap bales as soon as possible. Asking for extra layers of plastic will add about $3 a bale. It is good insurance against holes and your bales are likely to keep longer.   Do not make balage from a paddock contaminated with dung, especially one fertilised with poultry manure. Move bales as soon as possible after wrapping to their final resting place, and do not move them again.   Check bales regularly for holes and tape them up.   Get the moisture content right at baling to increase your chances of good balage. Wetter balage not only runs an increased risk of clostridial spoilage, it can also be damaged through freezing. If the grass is getting too dry, make hay.   Never use a tedder unless it allows you to get it baled before rain strikes. Tedding usually shouldn't be necessary - the "fluffing up" that results will only serve to put more air into the finished bale, which you don't want.   Ensure the rake doesn't contact the ground, stirring up dust which can put clostridial bacteria on the grass.   Avoid baling small-animal carcasses with the grass.   Store balage with some shelter from the sun. Fermentation is at its best in the range of 15 to 25degC. Higher temperatures favour clostridial bacteria, so avoid storing balage where its temperature is likely to exceed 30deg.   The more even the temperature during the fermentation and storage, the better.   Don't stack the bales.   When feeding a bale out over several days, close the plastic back over the opening to keep air out as much as possible.

This is why it's important to use grass when it's younger and still has high sugar levels. Some contractors will not cut the grass until after lunch. The longer the sun is on the grass, the higher its sugar content.
C'est pour cette raison qu'il est important d'utiliser de l'herbe jeune avec un taux élevé en sucres. Certains contractants ne vont pas vouoir faucher l'herbe avant le déjeuner, car plus le soleil est élevé, plus le taux en sucres suit le mouvement.

While the ultimate pH achieved in your balage is important, the speed at which it gets there is also critical. The longer the bale stays outside the desired pH range, the more likely that bad bacteria can take hold.
OK, le pH final est important mais aussi le temps qu'il met à arriver à cette norme. Plus le ballot reste en dessous du pH désiré, plus longtemps les bactéries nuisibles vont subsister.

If all goes well, your wrapped bales should dip below pH 5.0 in a few days and, preferably, under a week. Fermentation will continue slowly for a few more weeks, but the critical pH has been reached.
Si tout va bien, vos ballots descendront sous le pH 5.0 en quelques jours et de préférence en moins d'une semaine. La fermentation va continuer doucement durant encore quelques semaines mais le pH critique a été atteint.

There are ways a contractor can help things along. If they use a baler that chops the grass as it is fed into the baling chamber, this will speed the process. They can also spray the cut grass with an inoculant, containing good bacteria and enzymes, or an acid-based preservative. Some would consider one of these options essential for any cut grass that has been rained on, or for grass that is drier than desirable.
Il y a diverses manières pour accélérer les choses. Si l'herbe est re-coupée au moment de l'enrubannage, cela va accélérer le processus. Ils peuvent aussi vaporiser un inoculant avec des bactéries et des enzymes adéquats ou un conservateur acide. On considère cela comme indispensable lorsqu'il y a eu pluie ou si l'herbe est trop sêche.

The risk with horses

Balage is a nutritious feed that many horses enjoy. Many hundreds of horse owners swear by it, saying their horses do well on it over the winter months.
Beaucoup de chevaux adorent le préfané. De plus en plus de propriétaires ne jurent que par le préfané, surtout en hiver.

However, it is important to recognise the risks and how to minimise them. Cependant il est important de connaitre les risques et de les minimiser.

The biggest worry is botulism. Horses are very susceptible to botulism poisoning, which usually proves fatal. Le souci principal est le botulisme. Les chevaux y sont très sensibles et l'issue est souvent fatale.

Botulism poisoning causes progressive paralysis. Muscle trembling will be apparent and the horse will lie down often. If you pull their tongue out, they will have difficulty pulling it back. They can only eat with difficulty and death normally results from breathing paralysis, or complications from the amount of time spent lying down.
Le butulisme provoque la paralysie. Le smuscles se mettent à trembler et le cheval va souvent se coucher. Si vous retirer la langue, le cheval aura difficile de la remettre en bouche. Il ne peut manger qu'avec difficulté et la mort survient par la paralysie du système respiratoire ou des complications à force de se coucher.

Poisoning results from the toxin produced by Clostridium botulinum. There are seven known kinds, each producing a slightly different botulin toxin. One variety is found in poultry manure; another thrives in the carcasses of dead animals. One is even found in fish.
L'empoisonnement provient de la toxine produite par le 'Clostridium botulinum'. Diverses variétés existent. L'une provient de la fiente de volaille; une autre des cadavres d'animaux; une autre des poissons.

Plastic fantastic: The wrap goes on, sealing off the bale from the atmosphere and getting the ensiling process under way.

The faster the bale reaches a pH of 5.0 or less, the less chance that clostridial organisms can take hold. Higher pH levels can also provide a suitable environment for listeria.
Plus vite le ballot atteint un pH de 5.0, plus on réduit le risque de toxines.

Bales made with a moisture content greater than 60 per cent also stand a greater chance of becoming badly affected by Clostridium botulinum.
Les ballots avec un taux d'humidité supérieur à 60% ont aussi moins de chances d'être affecté par le botulisme.

Clostridial spoilage arises from the production of butyric acid. The balage will be sour and foul smelling, often like ammonia. You are likely to find evidence of slime moulds. Never feed it out. In fact, do not feed out any mouldy balage, even if it still has that distinctive balage smell.
Si le ballot sent mauvais, souvent une odeur d'ammoniaque , ne pas l'utilser. Si le foin est moisi ne pas l'utiliser même si l'odeur reste typique du préfané.

The issue, as with most feeds for horses, comes down to quality. Most feeds have their dark side: Substandard hay can deliver dangerous moulds and trigger hay colic. Moist grain can carry dangerous mycotoxins. Badly made balage brings with it the risk of botulism poisoning.

Provided the balage is of high quality, evidence would suggest the risk is low, but each horse owner will have to make their own call. Like any feed change, it needs to be introduced gradually to a horse's diet.
Si le préfané est de bonen qualité, le risque est très limité. Cependant le passage au préfané doit se faire graduellement.

Dr Simone Hoskin, senior lecturer in ruminant and equine nutrition at Massey University's Institute of Veterinary, Animal and Biomedical Sciences, believes pit silage is more risky than balage because of its generally higher moisture content.
Dr Simone Hoskin croit que le silo est plus dangereux que le ballot, car ce dernier a généralement un taux d'humidité plus élevé.

"Wrapped silage (balage) can be a great feed for horses and can be very cost effective," she says, "although once a bale has been opened it should be used within a few days unless it is very cold or snowy weather, in which case it can be fine for up to 10 days - otherwise you can get secondary fermentation."
"Le préfané est une bonne alternative pour les chevaux et à un coût intéressant". "une fois qu'un ballot est ouvert, il doit être consommé dans les quelques jours sauf s'il fait très froid, auquel cas il peut durer 10 jours. Sinon, une seconde fermentation aura lieu.

Dr Hoskin considers the risk of botulism poisoning low, provided the balage is of good quality.

It is hard to escape the conclusion that New Zealand appears to be a low-risk area for botulism poisoning in stock. There have been no recorded cases of it in any species at Massey University in at least 10 years. It is known in birds, but there do not appear to have been any cases reported in cattle in this country. Even if cattle cases have come to light here, they would certainly rate as extremely rare.
La Nouvelle Zélande a beuacoup moins de risques de botulisme que d'autres contrées. Il n'y a pas eu de cas durant les 10 dernières années.

All this will no doubt provide considerable comfort to horse owners feeding balage, although it should be noted that horses are more susceptible to botulism than cattle.

Overseas, livestock have not been so lucky. Feed-related outbreaks of botulism have not only been linked to silage and balage - big-bale lucerne hay and oaten chaff have also been a source. This shows that any spoiled feed (not just balage) could potentially carry a risk of botulism and should never be fed out.
Ce n'est pas le cas dans d'autres pays où des cas de botulisme ont été rapportés, pas seulement à cause du préfané mais aussi à cause de luzerne ou de paille d'avoine.

The risk for horses may be low, but remember the golden rule: never feed spoiled, mouldy, or poor quality balage to horses.

Balage being bought should be tested for quality and the price should reflect the quality, says Massey University equine nutritionist Dr Simone Hoskin.

Most major suppliers get their product tested, she says. "If they haven't, you are quite within your rights to ask for it to be tested, or get it tested yourself."

A fresh 500g sample (preferably from the centre of a bale) can be sent by courier in a sealed plastic bag to a variety of labs for analysis, including the Massey University Nutrition Laboratory.

Horse owners otherwise risk paying too much for poor quality feed, she says.

Le préfané devrait être testé en qualité et le prix devrait être lié à la qualité. La plupart des gros fabricants testent leurs produits, mais s'ils ne l'ont pas été, vous avez le droit de le demander ou le faire vous même en envoyant un échantillon à un labo spécialisé, de préférence venant du centre du ballot.

Keep your friends

If you're feeding balage out by hand, have a dedicated set of clothing for the task, including gloves. The smell of balage is quite invasive, and not everyone will enjoy Eau de Silage. It's one of those smells that keeps on giving!
Portez des gants lorsque vous manipulez du préfané pour éviter d'incommoder vos proches avec ces odeur insistante.

Watch for the skitters

Balage can trigger loose bowel movements in some horses, probably through finding the feed too rich or acidic. The problem is usually overcome by providing hay with the balage.
Le préfané peut accélérer le transit chez certains chevaux. En incorporant du foin, le problème se règle.

What about a vaccine?

Veterinary reports in the United States have suggested vaccinating against botulism if feeding balage to horses. However, the inoculation requires two or three shots (with annual boosters) and is certainly not foolproof, mainly because it doesn't cover all varieties of the bacterium. Undesirable side-effects have also been reported. One vet suggested it was not a decision to take lightly. The vaccine does not appear to be available in New Zealand.
Des études vétérinaires aux USA suggèrent de vacciner contre le botulisme. La vaccination requiert deux à trois injections et un rappel annuel et n'est pas efficace sur toutes les toxines. Il y a aussi des effets secondaires. Le vaccin n'est pas disponible en NZ.