Endocrine Profiles, Haematology and Pregnancy Outcomes of Late Pregnant Holstein Dairy Heifers Sired by Bulls Giving a High or Low Incidence of Stillbirth

Abstract

The high incidence of stillbirth in Swedish Holstein heifers has increased continuously during the last 15 years to an average of 11% today. The pathological reasons behind the increased incidence of stillbirth are unknown. The present experiment was undertaken to investigate possible causes of stillbirth and to study possible physiological markers for predicting stillbirth. Twenty Swedish Holstein dairy heifers sired by bulls with breeding values for a high risk of stillbirth (n = 12) (experimental group) and a low risk of stillbirth (n = 8) (control group, group B) were selected based on information in the Swedish AI-data base. The experimental group consisted of 2 subgroups of heifers (groups A1 and A2) inseminated with 2 different bulls with 3.5% and 9% higher stillbirth rates than the average, and the control group consisted of heifers pregnant with 5 different bulls with 0%–6% lower stillbirth rates than the average. The bull used for group A1 had also calving difficulties due to large calves as compared to the bull in group A2 showing no calving difficulties. The heifers were supervised from 6–7 months of pregnancy up to birth, and the pregnancies and parturitions were compared between groups regarding hormonal levels, haematology, placental characteristics and calf viability. In group A1, 1 stillborn, 1 weak and 4 normal calves were recorded. In group A2, 2 stillborn and 4 normal calves were registered. All animals in the control group gave birth to a normal living calf without any assistance. The weak calf showed deviating profiles of body temperature, saturated oxygen and heart rates, compared with the normal living calves. No differences of the placentome thickness, measured in vivo by ultrasonography were seen between the groups. The number of leukocytes and differential cell counts in groups A1 and A2 followed the profiles found in the control group. In group A1, a slight decrease of oestrone sulphate (E1SO4) levels was found in the animal delivering a stillborn calf from the first 24-h blood sampling at 6 weeks to the second at 3 weeks prior to delivery, while the levels of E1SO4 at both periods in the animal delivering a weak calf followed the profile in animals delivering a normal living calf. During late pregnancy and at the time of parturition, the levels of E1SO4 and PAGs in animals delivering a stillborn or weak calf (from group A1) followed the normal profiles found in animals delivering a normal living calf. In group A2, low levels of E1SO4 and pregnancy associated glycoproteins (PAGs) over 24 h at both 3 and 6 weeks prior to parturition (<1.5 nmol/L) were recorded in animals delivering a stillborn calf. During late pregnancy and parturition, the levels of E1SO4 and PAGs were slightly lower during 30–50 days prior to delivery and increased with a lower magnitude at the time of parturition. In conclusion, our results indicate that the aetiology behind stillbirth varies depending on the AI-bulls used and is associated with dystocia or low viability of the calves. Deviating profiles of oestrone...

Aspectos morfológicos, vasculares e endócrinos de prenhezes produzidas por técnicas de reprodução assistida em bovinos

“…The estrone sulfate concentration in the SCNT group was lower than that in the IVF group 30 days before parturition and was lower than that in the CTRL group at term, which may indicate placental dysfunction in the SCNT group compared with the IVF and CTRL groups. Similar to our findings, for naturally conceived animals, the estrone sulfate concentration is slightly lower during the 30 to 50 days before parturition than during the final days of gestation, with a low-magnitude increase at the time of parturition (5). In the present study, there was no gradual increase in estrone sulfate in the SCNT and IVF groups compared with the CTRL group, as has been described by others (5).…”

“…Similar to our findings, for naturally conceived animals, the estrone sulfate concentration is slightly lower during the 30 to 50 days before parturition than during the final days of gestation, with a low-magnitude increase at the time of parturition (5). In the present study, there was no gradual increase in estrone sulfate in the SCNT and IVF groups compared with the CTRL group, as has been described by others (5). A slight decrease in estrone sulfate before parturition is related to stillbirth (5), indicating the potential use of estrone sulfate to monitor fetal well-being in animals at a high risk of being stillborn.…”

“…In the present study, there was no gradual increase in estrone sulfate in the SCNT and IVF groups compared with the CTRL group, as has been described by others (5). A slight decrease in estrone sulfate before parturition is related to stillbirth (5), indicating the potential use of estrone sulfate to monitor fetal well-being in animals at a high risk of being stillborn. The previously observed lack of preparation for parturition in cloned pregnancies (61) together with the present findings suggest that SCNT-derived pregnancies may have a less functional placenta.…”

Why Do So Many Calves Die on Modern Dairy Farms and What Can We Do about Calf Welfare in the Future?

“…A genetic predisposition has been posited due to the large variation in perinatal mortality in the daughters of different sires. Further investigations suggested placental dysfunction might explain such genetic differences [ 78 ]. In addition, the possibility of undetected intra-uterine infection causing chorioamnionitis and foetal mortality cannot be discounted [ 79 ].…”

Hormonal changes in dairy cows during periparturient period

“…80-90 days after calving PAGs are not detectable in maternal blood [Haugejorden et al 2006]. PAG's changes in concentration may be helpful in monitoring the health of the fetus in animals in which there is a risk that they may give birth to dead calves [Kornmatitsuk et al 2004]. Kindahl et al [2004] emphasized that PAG concentration is higher in fetus blood compared to the mother.…”