Abstract
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.
