By: Nicole Salo
Part 1 of 3
- In the first part of this series on Development of a Healthy Foal, we’ll have a look at the gestation of the foal, proper nutrition for mare and fetus, and the time line of endocrine in the mare and the changes the fetus goes through before birth.
Gestation of the Foal
Selecting a diet for your foal starts well before he is born, with proper nutrition for your mare. Maintaining your pregnant mare will indirectly maintain her growing fetus as well. Poor nutrition during gestation may lead to poor health in your growing foal later in life. Poor nutritional management of the pregnant mare has been linked with incidents of fetal abortion and developmental orthopedic disease (DOD) in the growing foal. Providing your mare with a healthy balanced, with emphasis on the last trimester and during lactation can help reduce such incidents.
Making sure that Mom is receiving proper nutrition is not the only concern at this time. Regular maintenance of the pregnant mare is also vital to the health of the fetus. Regular maintenance of the pregnant mare should include the following, under the guidance of your veterinarian:
- Deworming program targeted at pregnant mares
- Regular dental and health checks
- Vaccination program targeted at pregnant mares
- Regular farrier work
- Exercise program targeted at pregnant mares
Feeding Mom, Feeding Baby
During the first eight months of pregnancy the mare’s demand for nutrition does not differ much from an idle open mare. Feeding a balanced diet, including quality forage with a percentage of protein greater than 8% with free access to trace minerals should keep both mare and fetus happy and healthy during this time. As the mare progresses into her final trimester, nutritional demands increase drastically. Now is the time when the fetus does most of its growing, placing significant demands on the mare, nutritionally and space-wise. Since most of the mare’s abdominal cavity is starting to be taken up by the growing fetus, it is time for the mare to slowly start taking in more concentrates and less hay (leaving room for baby). During the last trimester, the mare’s intake of protein, dietary energy, calcium and phosphorus should be increased significantly. These new requirements maybe met by an increase of grain or a pelleted diet, along with a free choice trace mineral block fortified with calcium and phosphorus. Your veterinarian and a nutritionist will be of great help in this area.
Time Line of Endocrine in the Mare from Conception up to Birth
- Day 6: Conceptus has moved to the uterus and lives via uterine nutrients
- Day 15: Reproductive system receives message to continue pregnancy, keeping progesterone levels elevated until at least day 75 or pregnancy will be aborted
- Day 40: Endometrial cups appear, allowing the secretion of equine chorionic gonadotrophin
- Day 40-70: Maternal oestrogens spike than level out
- Day 210-280: Oestrogens spikes again, then decline as birth approaches
- Day 240-300: Progesterone levels out
- Last 7-10 Days: Prolactin increases as parturition impends
- Relaxin may be noted during the final days of carrying as well
- Cortisol levels are triggered by stressed, and may spike just before labour
- Prostaglandin F rises to a peak during the 2nd stage of labour
- Oxytocin rises to a peak around the same time Prostaglandin F does
Time Line of Growth and Changes in the Fetus from Conception up to Term
- Day 1 – 23: Basic body structures are formed, in a rudimentary state
- Day 16: Chorionic vesicle 2 – 4cm in diameter
- Day 20: Chorionic vesicle 2.5 – 4.5cm in diameter
- Day 21: Amnion complete
- Day 25: Attachment of fetus is seen
- Day 40: Chorionic vesicle 4.5 – 7.5cm in diameter
- Day 60: Chorionic vesicle 13.3cm x 8.9cm
- Day 26 – 80: Eyes, ears, limbs, genitals are formed
- Day 90: Chorionic vesicle 14cm x 23cm
- Day 95 – 112: Hooves get pigment, hair starts to appear on lips
- Day 120 – 270: Hair on body grows, including mane and tail
- Day 310 – 340: Allantoic sac quiet heavy, testes may drop and a fully developed fetus is born
Mare and fetus have been sporting some major changes over the last trimester – the fetus has grown rapidly, as with the size of Mom’s belly. The mare’s diet has been shifted to reflect such changes (as noted above) and now over the final weeks of gestation, some very exciting changes can be seen. Now is the time when the mare should be brought to a prepared foaling stall, or other preferred foaling area. She can be brought to the foaling stall as advanced as a month before her excepted foaling date, so she is aware of and relaxed with her surroundings. During this time the mare should still have plenty of turn out, allowing her a chance to exercise, reducing the chance of constipation during late pregnancy. As well, this is a good way for the mare to stay fit for foaling. Now is also the time to vaccinate the mare with any boosters she may need, under the guidance of your veterinarian. A change in diet to a slightly more laxative one may be needed, with plenty of free access to fresh water. As the due date approaches, the foal will start to rotate into the birth canal; this may spark an attitude change in the mare. Her attitude may change into one of annoyance with her little one bouncing around. If at anytime the mare appears to be showing signs of prolonged discomfort, it would be best to contact your veterinarian.
In the second part of this series on Development of a Healthy Foal, we’ll have a look at all three stages of labour, this is the most exciting and stressful part of waiting for your new foal to safely arrive!
Nicole Salo is an equine entrepreneur with experience in various parts of the industry, including: training, breeding, management, social media and online content. Nicole currently holds an Equine Science Certificate and Diploma in Equine Studies through the University of Guelph while aspiring to finish her Certificate in Equine Business Management.