The aim of this study was to examine whether the nutritional state in dairy cows during dry and early lactation periods impacts the conception rate after ovulation synchronization and fixed-time artificial insemination (Ovsynch/TAI). Fifty-four Holstein-Friesian cows were used. Blood samples were collected twice at 10 d prepartum and 30 d postpartum. Blood parameters such as glucose, nonesterified fatty acids (NEFA), hematocrit (Ht), blood urea nitrogen (BUN) and total cholesterol (Tcho) were determined. Of 54 cows, 39 were used for Ovsynch/TAI, since the other 15 cows were either bred on spontaneous estrus or diagnosed as ketosis, mastitis or endometritis and therefore not used. Conception rates after Ovsynch/TAI were 43.6%. Cows with low levels of glucose and BUN at 30 d postpartum showed lower conception rates after Ovsynch/TAI than cows with normal values (23.5% vs 59.1%, 27.8%
vs 61.1%,
P<0.05). These results indicate that low levels of glucose and BUN during early lactation periods infltience the conception rates after Ovsynch/TAI.
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