Question

I own several pony broodmares, all of which are in early lactation. This year, several of them are underweight on a hay-only diet, the same diet that kept them in healthy weight in the past. One aged mare has lost weight rapidly over the past two months. Her current weight is 735 lb (334 kg), and she appears to be a body condition score of 3 or 4, which is rather alarming compared to her usual moderately fleshy (BCS of 6) condition. I recently started her on a 5 lb (2.3 kg) of feed along with weight-gain and vitamin-mineral supplements. There is no grass in the field, but the mares have 24/7 access to round-baled, good-quality grass hay. I am confident the mares consume plenty of hay based on how quickly they go through the bales. My vet fears this year’s heat and dry conditions have taken a toll on all horses, especially lactating broodmares. What else can I do to improve condition of my mares, especially my 22-year-old?

Answer

The simplest diet evaluations are those that involve consumption of too much or too little digestible energy, resulting in a horse that’s obese or emaciated. These diets can be easily amended by increasing or decreasing intake and possibly switching feedstuffs. Cases in which horses seem to be consuming plenty of calories, but still aren’t gaining weight, can be challenging.

Knowing the location of the farm and the climate are important considerations. Weather and management can negatively affect horses. The heat of the summer can suppress appetite, so offering shade and shelter to horses that are housed outside may help.

Underlying health concerns should always be scrutinized in cases of rapid weight loss. Ensuring the ponies are up-to-date on all vaccinations, deworming, and dental work will rule out several potential causes of weight loss.

Performing a fecal egg count on each pony is the best way to assess and effectively treat parasite burdens. However, low fecal egg count does not translate to “clean,” as encysted small strongyles could be causing problems in your herd, and these do not always present on fecal egg counts. A veterinarian well versed in parasite life cycles can help create a workable deworming schedule.

Forage type and quality are extremely important factors in weight-loss cases. You mentioned that the mares and foals have plenty of access to good-quality grass hay throughout the day, which is ideal. Considering how the hay is offered (as round bales in a group-feeding situation), could dominant ponies be limiting the intake of their herdmates? Could, for example, younger mares be pushing away the twentysomething mare from the round bales? In groups of horses that are well acquainted, feed-related squabbles aren’t always characterized by gnashing teeth and flying hooves. Aged horses often recognize their standing in the pecking order and refuse to fight for feed, choosing instead to walk off and wait their turn.

The ponies experiencing weight loss would benefit from a source of high-quality legume hay, like alfalfa. This can be in the form of hay, cubes, or pellets. Pellets offer a consistent and convenient alternative to long-stem hay and can be chewed and digested easily by mares with poor dentition. The other benefit to alfalfa cubes or pellets is that soaking can provide a cool and hydrating snack.

Providing a high-calorie concentrate for milk production is often a necessity since lactation is an energy-demanding life stage. Although 5 lb (2.27 kg) a day may seem like a lot for a large pony, it can actually be increased. If adding a third meal is possible, this would be the best way to safely increase the amount of feed without risk of hindgut acidosis. When offering at least the minimum amount of a feed, basic vitamin and mineral requirements should be met, which means an additional micronutrient supplementation is not necessary.

Once a high-quality legume forage has been procured and a suitable concentrate has been identified and fed appropriately, focus should turn to supplementation.

Added hindgut support for the underweight mares consuming a concentrate is advised. The hindgut buffer EquiShure works to reduce the drop in pH that sometimes occurs with large grain meals. Stabilizing the hindgut pH also optimizes the environment for the microbial populations responsible for fiber fermentation. EquiShure has been helpful with weight gain, specifically in improving fiber digestion in senior horses.

In addition to an increase in feed, you could add a fat supplement, which would provide further energy. Vegetable oil is an economical option. I suggest acclimating the mare slowly to the oil, gradually increasing the amount by a tablespoon or two each day until you’ve reached a total of three-quarters to one cup per day. Stabilized rice bran is another useful fat supplement, and some horse owners prefer it to oil because it is cleaner and easier to feed.

When increasing the amount of fat in the diet, vitamin E should also be increased. Horses and ponies without access to fresh grass are missing out on an important source of vitamin E. Because hay rapidly loses vitamin E after harvest, feed is left as the only source of the vitamin. Although vitamin E is included in good-quality feeds, some horses require additional supplementation. The natural-source, liquid supplement Nano-E provides highly absorbable levels that meets requirements and provides body-wide antioxidant benefits. The antioxidant support from Nano-E would be extremely helpful in boosting the immune system of aged mares and passing along those benefits to nursing foals.

Although you may not see drastic weight gain results during lactation, the goal is to provide more calories than they are consuming currently in order to prevent further weight loss. The addition of a legume forage source, increase in feed intake, and fat supplementation should help body condition. Continue to work with the veterinarian to ensure there are no other health concerns surrounding the weight loss and try to keep your ponies as comfortable as possible in the hot temperatures.