Modern Alternative Methods Of Pregnancy Diagnosis In Dairy Cows: Milk Progesterone Testing (MPT) as a Screen-Test for Non-Pregnancy at Day 24 after Breeding

Abstract

Literature pertaining to methods of rapid and inexpensive milk progesterone testing is reviewed. Progesterone testing provides insights into the endocrine changes normally associated with pregnancy. By using borderline concentrations set to discriminate for corpus luteal (CL) activity at Day 24 after breeding a lower progesterone concentration than the borderline indicates that a cow is not pregnant and a higher concentration indicates a high possibility of pregnancy. Positive results are probably correct in 90- 100% (average 95%) of the cows, negative results have a low accuracy (60-95%,  average  81%)  because  of  penalty  of  early  embryonic  mortality  and irregular cyclicity. As a background to aid the understanding of milk progesterone testing and factors affecting progesterone concentrations in milk, a brief discussion on progesterone variations in blood and milk during the oestrous cycle is included in this review