By Roxanne Trusty, CHS Nutrition Consultant
In the ebb and flow of the equine industry one area tends to be the greatest indicator of how the industry is trending as a whole: how many mares are being bred. Professional breeding facilities and home bred mares alike follow this same trend and both of their success rates depend greatly on following a nutritional program designed around the specific needs of their mares, stallions and foals.
In a 1990 survey performed by the Jockey Club representing 1,201 thoroughbred mares bred in 1988:
- 82% of bred mares were reported to be pregnant
- Of those ~1,069 mares reported to be pregnant:
- 10% resorbed or miscarried
- 6% aborted or had a premature birth
- Of those ~1,069 mares reported to be pregnant:
This survey then went on to follow the ~897 mares that successfully gave birth through the first year of the foal’s life and included statistics on health problems and mortalities of foals postpartum. Overall, this study found that of the live birth foals recorded:
- 42% suffered some form of health problems (~377 foals)
- 11% of those foals with health problems died within their first year of life (~42 foals)
Of course, you cannot look at one survey to base all of your equine breeding statistics on, however, this survey does effectively portray the real struggles in conceiving and birthing a healthy foal.
As technology advances in reproductive hormone therapies and A.I. techniques, one tool that remains the most effective and provides lifelong effects for the mare and foal is proper nutrition.
Preparing the Foundation
At the start of every nutritional plan we must begin with a body condition score. There has been much research around the importance of adequate body condition, not only at the time of birth and lactation, but also leading up to and at the time of conception. According to the AgriLIFE Extension (a part of the Texas A&M System), research has shown that mares with a body condition score (BCS) of less than 5 do not breed as well as mares with scores greater than 5. Acting professor of reproduction at Auburn University, David Pugh, DVM, MA, Dipl. ACT, Dipl. ACVN states that broodmares with a BCS of less than 4 exhibit:
- Decreased conception rates
- Increased fetal wastage (fetal loss)
- Decreased milk production
The lack of body composition directly affects the mare’s ability to cycle regularly, making estrus synchronization and observation much more difficult. Even more importantly, mares with a BCS of 5 or greater are more likely to maintain their pregnancy.
For optimal breeding efficiency a mare should be maintained at a BCS of 5.5 to 7.5 for at least 45 days before the expected time of breeding. Continue to monitor the mare’s BCS throughout her pregnancy and lactation. Changes in a mare’s BCS are a clear indication of her energy requirements and maintaining her condition means those energy requirements are adequately being met for her current stage of reproduction.
Use the Henneke model for monitoring a mare’s body condition score ( https://ker.com/tools/library/horse-body-condition-score-chart/ ). Using this scoring system rather than measuring changes in the mare’s physical weight can tell you more accurately whether the energy needs are being met appropriately. Being vigilant to maintain a mare’s BCS between a 5.5 and 7.5 throughout gestation and lactation will increase your chances of a successful breeding season and reduce the stress put on the mare.
Along with monitoring BCS throughout pregnancy and lactation the National Research Council’s Recommendations for Nutrient Requirements of Horses compares the energy requirements for different production stages in Table 1. Energy requirements of a mare grows throughout pregnancy, but peak in the first month of lactation. Lactation has the highest demand on energy over all other production stages, with most mares consuming 2.5-3% of their body weight in combined forage and concentrates.
Supplying the Building Blocks
There are many other nutrient balances that play a major role in the health of a mare and her growing fetus. The visual description of vitamins and minerals being the building block of life really takes hold when talking about reproduction. The importance of supplying a quality, balanced nutrition to your mare as she is developing the fetus and to a growing foal is like putting together the 5,922-piece Taj Mahal (see Figure 1.) If the builders of the Taj Mahal only made one brick size this mausoleum would not be the spectacle that it is today. Just like if we only focus on one nutrient, say energy or protein, we would not be able to build a healthy foal.
Along with an adequate BCS, a mare’s body requires a number of valuable vitamins and minerals to ensure her body is ready to conceive. Zinc and copper are two major building blocks for maintaining estrus, increasing conceptions rates and to developing healthy tissue in the uterus for the fetus/placenta to connect with.
At the time of conception copper plays a major role in early embryonic survival as well as fetal development throughout the pregnancy as shown in the research done by Zinpro Performance Minerals (http://www.zinpro.com/species/equine/mineral-details). Research has also shown how Manganese is used in the synthesis of the reproductive hormones the mare is continuously producing to sustain her pregnancy.
Although the trace minerals Zinc, Copper and Manganese play a huge role in conception, fetal development and foal growth, the NRC requirements for these building blocks in the diet does not increase significantly. Hence the name, “trace mineral.” See Table 2. What little space these trace minerals take up in the total of your mare and foal’s diet cannot compare to the devastation that low conception rates, fetal loss, dystocia and numerous musculoskeletal problems in newborns and developing juveniles display with diets deficient of these nutrients.
Vitamins are another tiny building block that create a significant impact on reproduction. The two major classes of these building blocks are fat soluble vitamins (A,D,E,K) and water soluble vitamins (B, C). The vitamin with the most significant requirement increase in pregnancy and lactation is Vitamin A. According to the 2007 NRC Recommendations for Nutrient Requirements in Horses shows the requirement for vitamin A doubles at the time of conception as it is a major building block in producing a heathy placenta.
A couple slightly larger building blocks whose requirements do significantly increase through pregnancy and lactation are the macro minerals, Calcium (Ca) and Phosphorus (P). As seen back in Table 1, a mare’s Ca requirement almost triples in the first month of lactation and is still double that of her maintenance requirement in her 5th month of lactation. This may not come as much of a surprise as it is well documented that Ca is a major component in the milk a mare is making for her young foal. Calcium along with Phosphorus and Magnesium, are three macro minerals that must be balanced for optimal use in mare health, fetal development and foal growth. These three minerals are used along with the trace minerals Zinc, Copper and Manganese for skeletal and joint formation. For the safety and health of your mare it is vital to keep a 2:1:0.5 Ca:P:Mg ratio as these three macro minerals interact with each other for absorption as well as muscle contraction and release.
The final building block we put into an equine feeding ration is protein. Similar to Calcium requirements, crude protein requirements more than double by the first month of lactation and remain increased throughout lactation as seen in Table 1. Protein is an area of continued research as this nutrient is used in a unique fashion by the body. Crude protein is broken down by the body into its own building blocks called amino acids i.e. lysine and methionine. There are multiple forms of amino acids that are used to build various parts of the body, more than just muscle. As research teaches us more about how the body uses specific amino acids for body growth and maintenance an equine ration can be fine-tuned with the specific levels of these quality amino acids for fetal development and foal growth. (My personal radar is focused on second trimester muscle cell development and fetal programing. But we’ll have to discuss that another time.)
You Can’t Mix Cement without Water
As total feed intake increases to meet nutrient requirements, the final nutrient to keep in plentiful supply is water. Water requirements can vary greatly depending on multiple factors including hot weather conditions, increased activity and all stages of lactation. Mares that are consuming more feed to meet their energy requirements tend to consumer more water as well. Always have fresh, clean and cool drinking water available as this is the number one nutrient for all classes of equine.
Consulting a Contractor
By now you may feel like you’ve been sent to the building supply store holding a shopping list without numbers. Building a ration from scratch can be complicated to say the least. Consulting with an expert in equine nutrition is highly recommended. A skilled nutrition consultant can supply you with tools like forage and water testing. Nutrition consultants are also a great resource for more indepth knowledge on high quality, fortified feeds and supplements like Equis Generation and Equis Ultramin.
Another great contractor to work with is your veterinarian. Working with your veterinarian to monitor BCS as well as possible ultrasound technologies can greatly increase your chance for a successful breeding season.