The effect of dietary protein on reproduction in the mare. VII. Embryonic development, early embryonic death, foetal losses and their relationship with serum progestagen.
Sixty-four Thoroughbred and Anglo-Arab mares aged 6-12 years were randomly allocated to 4 dietary groups and fed diets that differed in the total protein content and quality (essential amino-acids). Forty mares were non-lactating and 24 lactating. Eight mares were withdrawn from the investigation owing to injuries or gynaecological pathology. An overall conception rate of 94.6% and a foaling rate of 80% was achieved. Five of 14 (35.7%) mares (Group 1) fed a low-quality protein diet suffered from early embryonic loss before 90 days of pregnancy compared to 3 of 41 (7.3%) mares in the remaining groups that received the higher-quality protein in their diets. Serum progestagen concentrations of mares in Group 1 that suffered foetal loss were indicative of luteal function insufficiency during the 1st 40 days post-ovulation. Non-lactating mares in all 4 groups gained on average approximately 30 kg in mass during the 90 days before the breeding period. Lactating mares in Group 1 (low-quality protein) lost on average 25 kg in mass during lactation, with no weight loss observed among the lactating mares in the other 3 groups. No difference in the diameter of the embryonic vesicle was found between dietary groups until Day 35 of pregnancy.
van Niekerk
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Department of Human and Animal Physiology, University of Stellenbosch, Matieland, South Africa.
van Niekerk
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CH
D000818:Animals; D003627:Data Interpretation, Statistical; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000592:standards*; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D005313:Fetal Death / Q000097:blood / Q000662:veterinary*; D006736:Horses / Q000097:blood / Q000196:embryology / Q000502:physiology*; D007774:Lactation / Q000097:blood; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood / Q000502:physiology*; D011372:Progestins / Q000097:blood*; D012098:Reproduction / Q000502:physiology
D004044:Dietary Proteins; D011372:Progestins