The influence of subclinical ketosis and possible risk factors on the first service conception success in US dairy cows
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Abstract The objectives were to 1.) determine if a higher betahydroxybutyrate(BHBA) level (≥1.2 mmol/L) measured at 5 days in milk (DIM) results in a lower first service conception success; 2.) study the relationship of BHBA ≥ 1.2 mmol/L measured at 5 DIM with the following variables: season, parity, body condition score at calving (BCSCavC) and 40 DIM (BCS40C), retained placenta (RP), metritis, mastitis, respiratory diseases (Resp), displacement abomasum (DA), lameness (Lame), clinical endometritis (CE), cyclic and AI at estrus. The null hypothesis is that there is no association between BHBA ≥ 1.2 mmol/L and first service conception success. From November 2012 to august 2013, 1197 Holstein-Friesian cows were studied. Cows were enrolled at calving till the second pregnancy check on 60 ± 3 days after first insemination. Cows were excluded if sold or dead within 60 DIM or when data was incomplete. The definition of P32AI1 is the presence of an amniotic vesicle holding an embryo with heartbeat at 32±3 days after first artificial insemination (AI). Subclinical ketosis (SCK) is defined as serum concentrations of BHBA ≥ 1.2 mmol/L. Cows were inseminated when standing heat was observed or after timed AI (TAI). All cows had serum blood collected on day 5 post-partum from the coccygeal artery or vein and were analyzed for concentrations of 3-OH-butyrate (BHBA; Autokit 3-HB, Wako). For the statistical analyses 1041 Holstein-Friesian cows were included. All analyses were performed with the SAS system version 9.3. Elevated BHBA (≥1.2 mmol/L) concentrations measured with the Wako-kit on 5 DIM are not associated with pregnancy after first service. The logistic regression model with P32AI1 as response variable selected by backward elimination includes 2 variables that were significantly associated; RP and mastitis; 3 variables that have a tendency toward statistical differences; DA, Lameness, and CE. So, the probability to become pregnant after first service with RP, mastitis, DA, lameness or CE is smaller than to become pregnant without these diseases. The logistic regression model with BHBA (≥1.2mmol/L) as response variable shows a statistically significantly relationship between season, parity, BCS at calving, mastitis, DA, and a tendency for statistical difference for BSC at 40 DIM and CE. The odds of having SCK in summer was 1.7 times greater than the odds of having SCK in winter. Primiparous had lesser odds of SCK than multiparous. Cows with a high (≥3.5) BCS at calving have 2.4 times greater odds of SCK than cows with a BCS lower than 3.0. Cows without DA were 0.5 times as likely to develop SCK as cows with DA. The odds of SCK in cows with BCS ≥ 3.5 at 40 DIM was 0.5 times less than the odds of SCK in cows with BCS < 3.0 at 40 DIM. The odds of SCK in cows without CE was 0.7 times smaller than the odds of SCK with CE. The odds of SCK without mastitis is 1.8 times more than the odds of SCK with mastitis. This is the first study reported such a relationship between SCK and mastitis.