Immunoreactive faecal progestins as indicators of reproductive status
Larter, N.C.; Rajamahendran, R.; Sivakumaran, K.
Veterinary Record 134(18): 474-475
1994
ISSN/ISBN: 0042-4900 PMID: 8059514 Document Number: 423035
Paired faecal and blood samples from 17 Holstein cattle (6 pregnant cows, 2 cyclic cows (mid-luteal phase), 4 post partum cows and 5 adult bulls) were examined to determine whether changes in circulating progesterone levels were reflected by similar changes in faecal progestin levels. Faecal samples were divided and either freeze-dried or oven dried before extraction with methanol or ether. All plasma and extracted faecal samples were assayed for progesterone/progestin using the coat-a-count solid phase progesterone radioimmunoassay kits (Diagnostic Products). There were significant differences in the progesterone concentrations in the blood plasma for the different animal types. Plasma from pregnant and cyclic cows had progesterone concentrations at least 9-fold greater than did plasma from bulls and post partum cows. The same pattern occurred with the concentrations of progestins from faecal material. Plasma progesterone and faecal progestin concentrations were positively correlated regardless of extraction procedures; correlation was closest for oven drying with either extraction. The absolute progestin concentrations were lower when faecal material had been freeze dried than when it had been oven dried. Relative progestin concentrations differences between animal types were the same. The study demonstrated that faecal progestin assays are feasible alternatives to plasma progesterone assays. Because of the similarity in hormone concentrations in non-seasonal breeders it may not be possible to accurately assess their pregnancy status; in seasonal breeders, out of season faecal progestin levels would be low in non-pregnant animals and high in pregnant animals and the assay could be used to confirm pregnancy.