The effect of dietary protein on reproduction in the mare. VI. Serum progestagen concentrations during pregnancy

• Published in: Journal of the South African Veterinary Association Vol. 69; no. 4; pp. 143 - 149
• Main Authors: Van Niekerk, F.E, Van Niekerk, C.H. (Stellenbosch Univ. (South Africa). Dept. of Human and Animal Physiology)
• Format: Journal Article
• Language: English
• Published: South Africa South African Veterinary Association (SAVA) 01.12.1998
• Subjects: AFRIQUE DU SUD; Animals; Data Interpretation, Statistical; Dietary Proteins - administration & dosage; Dietary Proteins - standards; EQUIDAE; Equine; Female; GESTACION; GESTATION; JUMENT; Lactation - blood; MARES; PREGNANCY; Pregnancy, Animal - blood; PROGESTAGENE; PROGESTAGENOS; PROGESTATIONAL HORMONES; Progestins - blood; Protein nutrition; PROTEINAS; PROTEINE; PROTEINS; Reproduction - physiology; Serum progestagen; SOUTH AFRICA; SUDAFRICA; YEGUA
• ISSN: 0038-2809; 1019-9128; 2224-9435
• DOI: 10.4102/jsava.v69i4.843

Sixty-four Thoroughbred and Anglo-Arab mares aged 6-12 years were used, of which 40 were non-lactating and 24 lactating. Foals from these 24 mares were weaned at the age of 6 months. Non-lactating and lactating mares were divided into 4 dietary groups each. The total daily protein intake and the protein quality (essential amino-acid content) differed in the 4 groups of non-lactating and 4 groups of lactating mares. The mares were covered and the effect of the quantity and quality of dietary protein on serum progestagen concentrations during pregnancy was studied. A sharp decline in serum progestagen concentrations was recorded in all dietary groups from Days 18 to 40 of pregnancy, with some individual mares reaching values of less than 4 ng/mℓ. Serum progestagen concentrations recorded in some of the non-lactating mares on the low-quality protein diet increased to higher values (p<0.05) than those of mares in the other 3 dietary groups at 35-140 days of pregnancy. A similar trend was observed for the lactating mares on a low-quality protein diet at 30-84 days of pregnancy. No such trends were observed in any of the other dietary groups. High-quality protein supplementation increased serum progestagen concentrations during the 1st 30 days of pregnancy. Lactation depressed serum progestagen concentrations until after the foals were weaned.