With the appearance of some milder weather it is now not hard to imagine that spring is just around the corner and breeding season will soon be upon us.

Nutrition plays a key role in reproductive success for both mares and stallions and some attention to detail can prevent many fertility problems from occurring and can even help alleviate any historical issues.

Body condition

How your mare has been occupied prior to this coming breeding season can have an impact on how successful this year's covering will be.

It is essential to ensure that your mare comes into and out of lactation in as good a body condition as possible, especially if you are planning on breeding from her again. The ideal body condition score for breeding is good to fleshy or 3-3.5.

If you are planning on breeding from a mare that has been out of work for a while you may find that she is over conditioned and this too can have an adverse effect.

Some trials suggest that there is no deleterious effect of the mare being fat. However, concerns with laminitis and insulin resistance etc would dictate that it would not be wise to have your mare in fat condition.

At the other extreme, if your mare has been in hard work, eventing, racing or hunting, it may take a while for her reproductive cycle to re-establish itself.

In the majority of cases this will be due to the fact that her body condition or body fat level is too low. Another consideration is that she is likely to have come out of a high stress environment and stress hormones can have an adverse effect on reproductive hormones.

Work done in female long distance runners has shown that high levels of exercise can result in an irregular menstrual cycle and at extremes the reproductive cycle may even stop completely. The same effect can occur in mares and it may, therefore be worth ensuring that these mares are given several months to 'chill' and build up body fat reserves, before being asked to breed.

Stallions

Stallions should also be in good condition with a condition score of between 3-3.5 at the beginning of the breeding season and this condition maintained throughout.

Excess fat in stallions may be detrimental to breeding success as high fat levels can result in lowered levels of circulating testosterone.

Another complication arises when stallions have fat accumulation in the sheath area; resulting in reduced sperm counts and quality, due to impairment of temperature regulation in the scrotum.

A stallion covering mares throughout the breeding season is considered to be in light-medium work depending on how busy he is and should therefore be treated as such. It is vitally important to monitor your stallion's weight (using a weight tape) as any sudden changes in condition (up or down) will also affect fertility.

Flushing

The jury is out as to whether 'flushing' works in the mare. The practice of flushing means the mare is placed on a rising plane of nutrition for 4-6 weeks prior to planned service time, in order to optimise fertility rates.

It most definitely does not work in pregnant mares that you are planning on breeding at their "foal heat" and is in fact discouraged. In maiden or barren mares it will do no harm and may in fact help.

As in other heat exhibiting animals it is more likely to be the absolute body condition of the mare that affects the reproductive hormones and therefore fertility, rather than a short term increase in nutrition.

This practice is more likely to work in mares that are running up a little thin after the winter. It is of course no mere coincidence that the majority of mares will cycle most strongly during the spring flush of grass, and this is in fact nature's way of flushing your mare. There is a lot to be said for allowing Dr Green to do his bit before sending your mare off to stud.

Essential fatty acids

Recent research has shown that fatty acids (particularly omega-3) are necessary for good fertility in the horse.

Essential fatty acids (EFAs) cannot be manufactured in the horse's body and therefore must be part of the horse's diet on a daily basis. The two most important EFAs are omega-3 and omega-6 fatty acids and the correct balance of these in the horse's body.

The natural grass diet of the horse is high in omega-3. Cereals (oats, barley etc), on the other hand, are rich in omega-6 with very little omega-3.

The traditional high cereals diet can therefore result in an imbalance of omega 6:3 with most horses getting far too much omega-6 and not enough omega-3. This imbalance can have a deleterious effect on the horse's reproductive hormones.

To redress this balance it is necessary to supplement omega-3 into the horse's diet. The best source of omega-3 is cod-liver oil (DHA and EPA) and not much is required to convey benefits to the breeding horse.

Vegetarian sources of omega-3 include flax oil (ALA) and linseed oil which are further processed by the horse (ALA to DHA and EPA).

Omega-3

Research has shown that feeding the correct balance of EFAs, by supplementing stallions with fish oil results in an increased number of healthy sperm cells and an improvement in sperm motility

There has also been research which shows that supplementing the stallion's diet with fish oil results in sperm which are more resilient to cooling and freezing, having a much higher motility post thaw than cooled/frozen sperm from stallions not supplemented with fish oil.

Supplementation with fish oils should, therefore, be considered for stallions used for AI.

Mares fed on oils high in omega-3 (eg cod-liver oil) are shown to have improved reproductive hormone profiles resulting in a mare that will cycle sooner, more consistently and will get into foal more easily.

Health benefits including; improved skin, hair and hooves, fewer skin allergies, improved joint health and bone density, improved immunity and resistance to infection are all passed onto the foal in-utero and through the mother's milk during lactation.

Feeding breeding stallions and mares oils containing higher levels of omega-3 (fish oil, flax/hemp oil and linseed oil), will improve reproductive efficiency.

It is particularly beneficial to horses that are on restricted grazing (eg less than 18 hours/day). High oil diets will require supplementation with vitamin E.

Trace elements

There are many claims that increased levels of trace elements such as zinc and selenium will result in improved fertility (particularly in stallions).

There is, however, no scientific evidence for this. If the mare and stallion are fed a well balanced diet in the first instance then there will be no benefit seen from feeding higher levels of selected trace elements.

In fact, over supplementation of individual trace elements can in some instances do more harm than good.

Most improvements will be seen in horse's that are already lacking in that particular trace element. Balancer pellets can fulfil a useful role for both stallions and mares providing all the trace elements, vitamins, minerals and quality protein they require without the added calories.

These balancers can be further supplemented with oil (preferably high omega-3 oil), sugar beet, alfalfa etc, as required, to maintain that optimal condition score.

Breeding animals should be fed a well balanced diet, which can be achieved by feeding the correct level of a quality compound feed or by feeding a balancer pellet.

The most important thing is to ensure that body condition score stays at 3-3.5 for the duration of the breeding cycle for both mares and stallions.

Research has shown that fertility can be improved in both mares and stallions by ensuring that any oil supplemented has a high content of omega-3 fatty acids.