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Abortion
By: "Nutrient Requirements Of Goats"
"Number 15, 1981, National Academy Press"
About the Author
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The goat is more susceptible to abortion than other species of domestic livestock. Most of the work relating to abortion in goats has been with the Angora (Van Heerden, 1963; Van Rensburg, 1971; Shelton and Groff, 1974), in which the problem is more severe. Infectious diseases such as brucellosis are also capable of causing abortion in goats (Alton, 1973). The fact that the goat is a corpus luteum-dependent species predisposes the animal to abort whenever there is an interference with a functional corpus luteum (Wentzel et al., 1975). A low level of abortion is common with the Angora under normal production conditions, but catastrophic losses sometimes occur. Most abortions occur in response to stress between 90 and 110 days of gestation. Undernutrition during the critical stage of rapid fetal development and competition for nutrients between fetal and maternal organisms appear to be one explanation. The incidence of abortion is reduced in flocks in which replacement does are fed for proper size and development prior to the first breeding season and during gestation (Shelton and Stewart, 1973).
A series of studies from South Africa appears to provide a physiological explanation for the type of abortion observed in that country with the Angora. Parturition, either at or prior to term, is normally initiated by elevated corticosteroids of fetal or maternal origin (Wentzel and Roelofse, 1975). Two types of abortion have been identified in the Angora. One is known as stress abortion, which is triggered by low maternal blood glucose (Wentzel et al., 1976). This type is normally induced by poor nutritional condition of the doe (Wentzel et al., 1974), but other stress factors are also involved. Stress abortion is identified by the expulsion of a live or fresh fetus. Low maternal glucose appears to trigger hyperactivity of the fetal adrenal. The cause of abortion in the 90-110 days of pregnancy is apparently explained by the fetal adrenal gland's producing elevated levels of estrogen precursors (Wentzel et al., 1976), and estrogens are known to be potent abortifacients (Wentzel et al., 1975). After 110 days the fetal adrenal is more mature and produces corticosteroids, which are slower acting or less potent abortifacients.
A second type of abortion is that by the habitual aborter. These goats can be identified by a history of abortion, and by the expulsion of a dead edematous or autolyzed fetus. This type of abortion apparently results from maternal hyperadrenalism. Both types of abortion may be triggered by undernutrition resulting in low blood glucose. Initial or stress abortions can be almost totally prevented by adequate nutrition and the elimination of stress.
About the author: The majority of this information was researched from various tests and sources.
"Nutrient Requirements Of Goats - Number 15, 1981, National Academy Press"
Subcommittee on Goat Nutrition
Committee on Animal Nutrition
Board on Agriculture and Renewable Resources
Commission on Natural Resources
National Research Council
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