8/ MAY 2024 THE RIDER Nutritional Considerations for the Broodmare


broodmares, body condition is a critical variable that impacts reproductive effi- ciency. When a mare’s body condition is below a 5 (on the Henneke 9-point system), they have lower conception rates than mares with a condition of 5 or higher. That being said, when a mare has a body condition above a 7 there are also serious concerns.


What does the nutrition look like in this pre-breeding period? A balanced diet is critical, but it


An Equine Nutrition Series by Madeline Boast, MSc. Equine Nutrition


Broodmare nutrition is an impor-


tant topic as nutritional requirements change throughout gestation and lacta- tion. In addition to paying close atten- tion to the changing nutritional requirements throughout a mare’s gesta- tion, it is recommended that a mare is on a balanced diet to support her in achiev- ing an optimal body condition prior to breeding as well. When you have a mare that you are


planning to breed, the first consideration starts with nutritional strategies to en- hance the likelihood of the mare becom- ing pregnant. Of course, nutritional management is crucial, but housing con- ditions, deworming, and regular veteri- nary care (e.g., vaccinations) are all extremely important factors in brood- mare health.


Preparing for Breeding When we evaluate the research on


doesn’t have to be complicated. Many broodmares will thrive on free-choice quality forage (please test your hay!!!) with a ration balancer. Of course, qual- ity forage can mean different things to different people, so a more precise way to say this would be for your mare to be maintained on a forage that has been


tested and is adequate for meeting her basic nutritional requirements. Nutri- tional deficiencies can be truly detri- mental, so having your forage tested and your mare’s diet balanced by a nutrition- ist is a worthwhile investment. Now that we have touched on the


easy keepers, what about the mares that struggle to maintain weight? Unlimited forage with a ration balancer simply isn’t enough for some horses, and to elicit weight gain a concentrate often needs to be added. There are two broad categories for concentrates; you have straight cereal grains and commercial concentrates. Both of these options work, however, I recommend the com- mercial concentrates as if you are pur- chasing from a reputable company a qualified equine nutritionist will have been involved in the formulation of that product and it will be balanced. The amount of concentrate that


needs to be added will depend on the mare’s current body condition, the time- line to meet her optimal body condition score and of course the caloric content of the commercial product being used. One nutritional issue I commonly see is


that people will have a horse that needs some additional concentrate but will feed below the manufacturer’s recom- mended amount. This typically equates to vitamin and mineral deficiencies – therefore, in these situations, a ration balancer may also need to be incorpo- rated or the commercial concentrate product may need to be exchanged for another. A nutritionist will be able to do all of these calculations for you. So, now that you have your horse


on a balanced diet that is supporting them in maintaining a healthy body con- dition, what dietary adjustments are re- quired during pregnancy?


Early Pregnancy During gestation, adequate nutri-


tion not only needs to be provided to the mare so that she can support herself, but she also must support fetal growth dur- ing this period. This is achieved either through processing additional nutrients in her diet or by relying on and pulling nutrients from her own body’s stores to meet the needs of the developing fetus. When I am designing a broodmare


diet, the goal is to minimize the need for the mare to use her own body stores. Therefore, as the mare’s nutritional re- quirements increase during gestation, her balanced diet should also change to meet these increasing needs. The NRC 2007 Nutrient Requirements of Horses states that the pregnant mare starts to re- quire additional nutrition in the 5th month of gestation. As the mare ap- proaches the 5th month, her diet will need to be altered to ensure it is meeting her nutritional requirements as they con- tinue to increase into late pregnancy and lactation.


Late Pregnancy Starting in month 5 of pregnancy


the energy and protein requirements both begin to increase. These will con- tinue to increase through the remaining gestational period. In month 7 is when


we begin to see increased requirements for minerals such as calcium, phospho- rus, and magnesium. The most significant nutritional


changes occur in the third trimester as that is when the majority of fetal growth occurs. Additionally, a mare’s appetite may decline towards the end of gesta- tion. This needs to be carefully moni- tored so that the diet can be altered to meet her increased needs, and if appetite is decreased an increase in concentrate is typically warranted. For broodmares during pregnancy,


it is not concerning if they are slightly over a body condition of 5 /9 as having some additional body fat can help to support milk production after the foal is born. However, this should be moni- tored carefully as a broodmare being obese can be detrimental to their well- being. When a broodmare is obese it is linked to larger foals and a higher inci- dence of delivery complications.


Lactation The highest nutritional requirement


for broodmares occurs at the beginning of lactation. The first two months of lac- tation require significant nutritional sup- port with a slow decrease in nutritional requirements throughout the remaining months of lactation. Also, remember that water is an essential nutrient. During the lactation period a mare will almost triple her water consumption. Therefore, large quantities of fresh water should always be available to your mare. When considering adding supple-


mental sources of nutrition above and beyond the forage, such as ration bal- ancers or commercial concentrates, one consideration that is commonly over- looked is the quality of ingredients. Many horse owners will go to the feed store and may look at the feed tag for crude protein percent but may not closely look at the ingredients. It is im- portant to remember that a horse re- quires essential amino acids, not just


‘crude protein’. Therefore when a mare has an increased requirement, the com- mercial product that you are feeding should incorporate high-quality ingredi- ents, such as soybean meal or alfalfa which supply essential amino acids.


Post-Weaning Post-weaning isn’t a period that


normally gets a lot of attention; how- ever, it is also a critical period nutrition- ally. Despite a great nutrition program, there is research to show that the mare will still mobilize some body stores, par- ticularly from their bone mineral (e.g., calcium) during lactation. Therefore, when we look at post-weaning, it pres- ents an opportunity for your mare to re- plenish those stores. It is not uncommon that a brood-


mare will be on additional supplemental feed during pregnancy and lactation, but then revert to a hay-only diet after wean- ing. Part of the reason this is often done is to prevent excess weight gain and re- duce the likelihood of mastitis develop- ing as there is research to suggest that reducing feed intake is a recommended practice for the prevention of mastitis. However, a ration balancer should still always be used, even for those easy keepers as your mare should always have a source of additional vitamins and minerals. Relying on a mineral block is not adequate. To conclude, a balanced diet is im-


portant through every step of pregnancy for the broodmare, nutritional deficien- cies can easily go undetected but can cause lasting health issues in the foal when born. Obesity in the broodmare can cause increased fetal adiposity which can affect growth and perform- ance as well. Due to the continually changing nutritional requirements, I highly recommend working with a nu- tritionist who can do all the nitty gritty calculations for you in these situations


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