Midwest Equine

Feature Article

Broodmare Nutrition - Conception to Colostrum

By Natalie R. Cooper, DVM
Vice President, Veterinary Medicine, Freedom Health LLC

Article Archives LinkBroodmare Nutrition - January 2018

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In order to ensure that foals are afforded the opportunity to thrive, their nutritional needs must be met by starting with a broodmare program that focuses on optimizing nutrient utilization. Current research highlights that mares on a rising plane of nutrition prior to and during breeding are more likely to conceive and carry a foal to term than their cohorts who are not maintained in an appropriate energy balance. Lack of appropriate body condition (BCS < 4 (1-9 scale)) can lead to incomplete ripening of follicles, delayed onset of estrus, and irregular estrus cycles, all of which contribute to decreased rates of conception. (Van Niekerk and Van Heerden, 1972; Belonje and Niekerk, 1975; Henneke et al., 1984 and Gill et al., 1983) Despite popular belief, no scientific evidence supports reduction of fertility in obese mares (BCS > 7 (1-9 scale)). (Cavinder, et al., 2005) There is also little evidence to support feeding a vitamin and mineral supplement to mares prior to breeding improves fertility, however; a deficiency in vitamins and minerals could certainly lead to decreased fertility and/or contribute to early embryonic death. (Ellis 2006)

Optimal body condition scores should be maintained throughout pregnancy and lactation in order to ensure return to estrus, as well as to ensure appropriate colostral immunity transfer, and optimize milk production. Note that it is not always necessary to feed concentrate to mares in early gestation if good quality forage is available. A small amount of ration balancer can be fed daily to ensure appropriate mineral and vitamin uptake. As nutrient requirements increase (around month 5 of gestation), mares may require supplemental feeding with a concentrate, particularly if they are housed out of doors during winter months. (Geor, et al., 2013) It is important that the addition of concentrate feed to the ration never exceeds 2 grams of simple sugar/starch per kg of body weight per meal, as any amount over this predisposes simple sugar/starch spill-over into the hindgut. This can lead to hindgut acidosis, bacterial inversion, and inflammation of the gut tissue, which can manifest clinically as nutrient malabsorption, colic episodes, and laminitis. (Harris 2006)

"Mares fed a polar lipid based supplement in the 90 days prior to foaling were shown to have a 97% increase in colostral IgG concentration."

As failure of passive transfer is one of the predominant causes of septicemia and death of the newborn foal, colostral antibody formation should also be considered when discussing the nutritional requirements of the peripartum mare. One study shows that mares fed a polar lipid based supplement in the 90 days prior to foaling were shown to have a 97% increase in colostral IgG concentration (average 14038 mg/dl colostrum) when compared to their cohorts that did not receive supplementation (average 7078 mg/dl colostrum). The supplement, although primarily used to support the health and functioning of the gastrointestinal tract, was shown to have immunomodulatory effects, and as such could be considered to be an option for broodmares with a history of poor colostral IgG concentrations. (Carter and Pellegrini 2006)

Finally, it is of importance to mention monitoring feedstuff for contamination. There is a known link between mycotoxin ingestion and fetal absorption, abortion, weak foals and infertility. (McCann, et al., 1992) Also, mycotoxin metabolites (zeranols) are sometimes used as growth promotants in cattle and swine feeds, so care should be taken with regard to feed isolation in mixed equine and livestock operations. (Fitzpatrik, et al., 1989) Fescue pasture and hay should also be monitored as endophyte contamination alters prolactin metabolism and decreases blood levels of progersterone. Mares that ingest toxic levels of endophyte are at risk for dystocia, thickened/ retained placenta, abortion and aglactia. (McCann, et al., 1992)

Careful planning with regard to the nutritional needs of broodmares prior to breeding and throughout pregnancy and lactation is essential for maintaining the reproductive soundness of the mare, as well as providing an optimal start in life to the foals they carry.

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