Post-insemination milk progesterone concentration and embryo survival in dairy cows.
Logistic regression analysis was used to evaluate the relationship between post-insemination milk progesterone concentration and embryo survival, and between milk yield and milk progesterone concentration. Milk samples were collected on Days 1, 4, 5, 6, and 7 (insemination=Day 0) following 871 inseminations in spring-calving dairy cows. Milk progesterone concentrations were measured by enzyme-immunoassay and pregnancy diagnosis was conducted with transrectal ultrasonography at approximately Day 30. There was a negative linear relationship (P<0.01) between milk progesterone concentration on Day 4 and embryo survival while, in contrast, there was a positive linear and quadratic relationship between milk progesterone concentration on Days 5, 6 and 7 (P<0.05) and also between the rate of change in progesterone concentrations between Days 4 and 7 inclusive and embryo survival (P<0.05). There was a weak negative linear relationship between average daily milk yield at the time of insemination and milk progesterone concentrations (P<0.001). There was no association between many production parameters, including liveweight and body condition score measured at various stages between calving and insemination, and milk progesterone concentration between Days 4 and 7 inclusive (P>0.05). In conclusion, low progesterone during Days 5-7 (after insemination) was associated with low fertility in dairy cows and there were indications of a range of progesterone concentrations within which embryo survival was maximal.
Stronge
A J H
AJ
Animal Reproduction Department, Teagasc Research Centre, Athenry, Co., Galway, Ireland.
Sreenan
J M
JM
Diskin
M G
MG
Mee
J F
JF
Kenny
D A
DA
Morris
D G
DG
D000818:Animals; D001823:Body Composition; D001835:Body Weight; D002417:Cattle / Q000502:physiology*; D020964:Embryo Loss / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000502:physiology*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary; D007774:Lactation; D016015:Logistic Models; D008892:Milk / Q000737:chemistry*; D011247:Pregnancy; D011374:Progesterone / Q000032:analysis*; D013997:Time Factors
D011374:Progesterone