Nikita Stowers MSc (Nutrition) BSc (Animal Science) BBS
Equine Nutritionist – Veterinary and Nutritional Integration LTD

When we need to feed horses hay

Hay is such a great source of fibre for horses in New Zealand and there are many reasons to include hay in our horses diet. Often we feed hay to fill the gaps in our pasture, or when pasture is not suitable for horses at certain times of the year. No matter what time of year it is or how much work our horses are doing, we must still meet their daily fibre requirement of 1.5 - 2% of their body weight in forage daily. There are times when it is impossible to do this on pasture alone. 

With pasture, it's useful to think in terms of 'dry matter', as this is the useful fibre in the grass, which would remain if we removed all the moisture. If you took a kilogram of grass from your paddock and completely dried it, you may only end up with 150gm of dry matter at certain times of the year. In Spring, when water content is high in our lush pastures, a horse could need to eat 50 - 70kg of fresh pasture every day just to meet their fibre requirements... sometimes it just isn't physically possible for them to get enough fibre from grass alone!

To understand a bit more about why we feed hay we have outlined the most common scenarios below, and covered the benefits and any risks associated with common horse hay types in New Zealand.

Our horse's hay requirements change with the seasons

As we are heading into Winter, most horses will need some form of hay or additional forage, because at this time of year the Dry Matter of our pasture will typically drop to around 15%. This means the grass's water content is high (around 85%) and horses will need some additional fibre, usually in the form of hay that has a water content of around 15%. This will make sure the good bugs in the horse's gut remain well fed and the horse gets enough fibre for the bugs to convert to energy. 

During Spring and Autumn we may also need to feed hay due to the 'sugar' (fructans) level and “richness” of the pasture. 

Because hay is cut later in the season, typically in late summer, the nutrient value of hay is typically lower than spring and autumn pasture.  It’s a great fibre source for horses that don’t do well on high sugar grass.  Because our horses' feed intake is pretty fixed each day, if we feed them some hay they will then consume less grass by default, so it allows us to control the diet when required. 

During Summer or a drought (or any times when pasture is not freely available) it may also be a good time to include some hay in the diet, because if we limit fibre intake below 1.5-2% this will start to have a negative effect on the bugs in our horses' gut and lead to weight loss.

Things to watch out for in your 2023 Hay 

New Zealand has been hit hard this season with all sorts of unusual and devastating weather including Cyclone Gabrielle, flooding and record levels of rain that have made the hay harvesting season tough. This has meant that haymaking conditions have been poor around the country, leading to reduced drying rates, and higher than desirable moisture levels in our hay this season. 

Many of our clients in the field have noted how heavy their bales are and this is a red flag for moist hay. Long drying periods and hay going into storage when it is not quite dry with high humidity can encourage mould growth on hay.  Moulds can grow on hay when the moisture level is above 14-15% so a quick dry matter test can tell you if you hay is at risk of mould growth.

Ensuring your hay storage place is well ventilated and there are spaces between bales can reduce the risk of your hay developing mould. These moulds can produce spores that cause respiratory problems and in some cases can also produce mycotoxins. Some of the symptoms of mycotoxin intake from hay include reduced appetite, reduced nutrient absorption, diarrhoea and negative impacts on the immune system.

Hay tip: Mycotoxin binders may help reduce the negative impacts of mouldy hay, however if you are in doubt don’t feed it or get it tested to be sure. Steaming hay can help reduce spore counts greatly. You can send samples for mycotoxin analysis, but the best strategy is to avoid feeding hay that hasn’t been properly dried or stored. 

What types of Hay are available in New Zealand - and which type is right for my horse?

There are so many variations of “meadow hay” in New Zealand that as a horse owner it is a good idea to delve a bit deeper into what we are actually buying or growing for our horses.

Your horses workload and/or stage of life can help you decide which hay to go for or avoid. For example, lactating mares, growing horses or horses needing to gain weight will do well on Lucerne hay or hay with a higher clover content due to it’s high calorie and protein level. However, these hays are less suitable for horses needing to lose weight.

Not all hay is a safe forage for all horses

For example, a prime cut meadow hay can be typically around 15% Non-structural carbohydrate (NSC or fructans).  For horses and ponies prone to Laminitis, with PPID or sensitivities to sugar we recommend feeds that are 10-12% or less in NSC, and therefore feeding this hay would be unsuitable for these horses and ponies unless it was soaked.

It is possible to get brown top, brome, timothy and other higher fibre, lower sugar hays that will be suitable for horses prone to Laminitis or that need a lower sugar fibre source.  It is also advisable to get hays that are cut later in the season for those horses that require a low sugar forage and if you are getting hay cut on your own hay, try not to cut right in the heat of the day (mid afternoon) as this is when sugars peak.

Hay tip: If the NSC (starch + sugar) level in your horse's hay is above 10-12% we recommend soaking your hay overnight and removing excess moisture to reduce the NSC level.

Rye / Clover Blend Hay

The most common hay type is still probably a rye/clover blend.  This hay can work well for many horses, but do keep in mind that because of its rye and clover content it is likely to be high in calories, sugar and protein.

Although Ryegrasses are common in New Zealand pastures, it is best to avoid Endophyte ryegrasses where possible.  These types of ryegrasses contain a fungus called an Endophyte.  An endophyte is a naturally occurring fungus that is found in ryegrass and tall fescue pastures. Endophytes are essential for persistence in most New Zealand pasture as it protects the plant from insect attack.  However, when a horse consumes these pastures they can suffer from a variety of symptoms including trembling, spooking and shying, increase in herd bound behaviours, and stagger like symptoms. These endophytes can remain in the hay for some time, so if purchasing ryegrass hay, try to ensure it is non-endophyte ryegrass.

Hay tip: Mycotoxin binders for horses have become popular in recent years; however most toxin binders aren’t effective on the grass based toxins you may find in your hay. Learn more here. 

Horse-safe Meadow Grass Hay

It is great to have a good variety of fibre in your hay as well.  Combinations of high fibre horse safe grasses such as Cockfoot, Timothy, Brome, Yorkshire fog and Browntop are all considered safe grasses for horses. 

However, keep in mind that even these grasses can be high in sugars depending on when they were cut and the conditions at the time.  If you have a horse that requires a low sugar diet for any reason (eg. Those with Laminitis or PPID) then we would always recommend testing your hay first so you can be sure it’s safe.  

Kikuyu Hay

In the more northern parts of New Zealand we see varying levels of Kikuyu grass in our pastures particularly in Auckland and Northland. We will therefore often see this as a component in hay as well.

Kikuyu contains high level of a compound called Oxalate.  The problem with Oxalate is that it binds up Calcium in the horses digestive tract so we need to make sure if feeding hay with high levels of Kikuyu in it that we add additional calcium to the diet.  How much additional calcium you require will depend on how much Kikuyu is in your hay.  If your diet has at least 0.5 part Calcium to 1 part Oxalate this is generally regarded as safe.  Kikuyu has a Calcium to Oxalate ratio of 0.23 parts Calcium to 1 part Oxalate so supplementation is required to bring the level up to at least 0.5:1. 

To discuss Calcium requirements for a horse grazing pasture high in Oxalates, you can reach out to us at VANI or see if your diet is safe on Feed Assist. 

Horses love lucerne so you rarely ever get ‘meals sent back to the kitchen’. Lucerne is also super nutritious; it contains lots of minerals (especially calcium), is rich in fibre and high in quality protein.

Hay tip: Lucerne hay is LOW in starch and water soluble carbohydrates (collectively known as the non-structural carbohydrates or NSC). Which means lucerne hay is SAFE for laminitic horses and ponies.

It is also high in calories, which makes it the perfect hay for horses needing to gain weight and build muscle.

I love lucerne as part of almost every horse’s diet. It adds great nutrition and it brings the aspect of variety in the form of a legume forage to the diet.

Lucerne is a high calorie hay, so for horses who are overweight it can be an issue. It should be fed in very restricted amounts as it is easy to make horses too fat on too much lucerne.

Lucerne’s high protein levels mean you can feed too much protein if you feed too much lucerne. For most horses this isn’t an issue. But for horses in stables it means their boxes will be wet and smelly (as they need to drink a lot and urinate more to rid the excess nitrogen from the protein out of their body). This excessive urination can also lead electrolyte depletion and in extreme cases, tying up in working horses. It is important to remember though that it is not the lucerne causing this as such; it is the excess protein. So if you feed appropriate amounts of lucerne, you won’t see these issues.

Its high calcium characteristic also needs to be managed carefully, especially for growing horses. Diets that contain only lucerne for youngsters will often have a calcium: phosphorus ratio that is too high, which can then cause phosphorus deficiency and may affect correct bone development.

Lucerne for gut health: A big thumbs up! Studies show lucerne helps gastric ulcers heal. It is a natural buffer so it is a great forage to feed just before you ride or work horses to fill their stomach up and protect it from ulcers too. Plus it is rich in essential amino acids so it will help support the guts needs for the amino acids it needs to stay healthy.