Effects of a protracted induction of parturition on the incidence of retained placenta and assessment of uterine artery blood flow as a measure of placental maturation in cattle

The objectives of the present study were to compare the effects of a protracted and a conventional induction of parturition on the incidence of retained placenta, and to evaluate the suitability of transrectal Doppler sonography of the uterine arteries as a noninvasive method for the assessment of placental maturation. Protracted induction of labor (PIP) was precipitated in 13 cows by the administration of 1.3 mg dexamethasone im twice daily between Days 268 and 273 of gestation, and 40 mg dexamethasone im on Day 274 of gestation. For conventional induction of labor (SIP), 10 cows received 40 mg dexamethasone on Day 274 of gestation. A third group was not treated and served as control (SPON; N = 11). Blood flow volume (BFV) and resistance index in the uterine arteries were measured with Doppler sonography once a day from Day 268 of gestation until labor. After each ultrasonographic examination, blood samples for determination of steroid hormones were taken. Incidence of retained placenta was lower (P 0.05) and did not differ between groups SPON, PIP, and SIP (P > 0.05). Resistance index was higher (P 0.05) between them. Total estrogen concentrations increased by 283% (P 0.05) until Day -2 in group SIP, but increased (P < 0.05) after the high dosage of dexamethasone within 1 day by 140%. Total estrogen levels were higher (P < 0.05) in cows with released placenta than in cows with retained placenta. In conclusion, a protracted compared with a short induction of labor results in higher estrogen levels before term, but does not affect incidence of placental retention. Neither alterations in placental maturation nor changes in steroid hormones influenced uterine blood supply. Therefore, Doppler sonography of uterine arteries is unsuitable to investigate the process of placental maturation induced by glucocorticoids in cows. Nevertheless, disturbances in the placental maturation process in cows with retained fetal membranes after parturition can be detected before parturition by a higher uterine blood flow resistance in the uterine arteries

Pathogen dependent effects of high amounts of oxytocin on the bloodmilk barrier integrity during mastitis in dairy cows.

The reduction of antibiotic use in food producing animals becomes increasingly important. Therefore, suitable alternatives for mastitis treatment in dairy cows have to be considered. Oxytocin (OT) induces milk ejection and hence supports milk removal from infected mammary quarters. Beyond udder emptying, the injection of very high dosages of OT causes increased somatic cell counts (SCC) in milk and enables the transfer of immunoglobulins (Ig) from blood into milk through a reduced blood-milk barrier integrity. The aim of the present study was to investigate pathogen-specific changes of SCC, the blood derived milk components lactate dehydrogenase (LDH), serum albumin (SA), and IgG in milk of cows suffering from mastitis caused by different pathogens treated with two intravenous injections of high dosages of OT (100 IU). Milk samples from 184 dairy cows from different farms were collected on day 1 (day of clinical examination and mastitis diagnosis) and on days 2, 3, 14, and 28. Bacteriological examination (day 1) identified involved pathogens. Cows were randomly assigned to treatment (OT injections on days 1 and 2) or control group (no OT). Independently of the assigned experimental group, cows received the common therapy protocol of the veterinary practice after sample collection if the general condition was affected. Milk SCC, LDH, SA, and IgG changed specifically depending on involved pathogens. Highest values of all three parameters were measured in mastitis caused by Streptococcus uberis. Changes were less pronounced with other Streptococci spp., Staphylococci spp. or Corynebacterium bovis. Oxytocin treatment did not affect any of the studied parameters independent of the involved pathogen. Only in quarters infected with Staphylococci other than Staphylococcus aureus a decreased SCC and increased IgG concentrations in quarters, where no pathogens were detected, were observed. Thus, high dosage OT administration is obviously not suitable as a stand-alone mastitis treatment in dairy cows

a review

It is well documented that global warming is unequivocal. Dairy production systems are considered as important sources of greenhouse gas emissions; however, little is known about the sensitivity and vulnerability of these production systems themselves to climate warming. This review brings different aspects of dairy cow production in Central Europe into focus, with a holistic approach to emphasize potential future consequences and challenges arising from climate change. With the current understanding of the effects of climate change, it is expected that yield of forage per hectare will be influenced positively, whereas quality will mainly depend on water availability and soil characteristics. Thus, the botanical composition of future grassland should include species that are able to withstand the changing conditions (e.g. lucerne and bird's foot trefoil). Changes in nutrient concentration of forage plants, elevated heat loads and altered feeding patterns of animals may influence rumen physiology. Several promising nutritional strategies are available to lower potential negative impacts of climate change on dairy cow nutrition and performance. Adjustment of feeding and drinking regimes, diet composition and additive supplementation can contribute to the maintenance of adequate dairy cow nutrition and performance. Provision of adequate shade and cooling will reduce the direct effects of heat stress. As estimated genetic parameters are promising, heat stress tolerance as a functional trait may be included into breeding programmes. Indirect effects of global warming on the health and welfare of animals seem to be more complicated and thus are less predictable. As the epidemiology of certain gastrointestinal nematodes and liver fluke is favourably influenced by increased temperature and humidity, relations between climate change and disease dynamics should be followed closely. Under current conditions, climate change associated economic impacts are estimated to be neutral if some form of adaptation is integrated. Therefore, it is essential to establish and adopt mitigation strategies covering available tools from management, nutrition, health and plant and animal breeding to cope with the future consequences of climate change on dairy farming

Fruchtbarkeit nach 6- und 12-tägiger Behandlung mit Eazi-breed™ CIDR® G ausserhalb der Zuchtsaison beim Lacaune Milchschaf

In dieser Studie wurde die Fruchtbarkeit nach Kurz- und Langzeitsynchronisation mittels Progesteron Intravaginalspange beim Lacaune Milchschaf ausserhalb der Zuchtsaison untersucht. Dazu wurden 108 Lacaune Milchschafe während 12 (Gruppe L, n = 60) oder 6 Tagen (Gruppe K, n = 48) mit einer Eazi-breed™ CIDR® G (Pfizer Animal Health, Zürich) intravaginal Spange in Kombination mit 500 IE eCG (Gruppe L) bzw. 500 IE eCG und 125 μg Cloprostenol (Gruppe K) bei Entfernung der Spange behandelt. Anschliessend wurden die Auen während 60 Tagen mit Böcken zusammen gehalten, die Brunsten protokolliert und die Fruchtbarkeit nach dem Ablammen erhoben. Bei Applikation und Entfernung der Spange, sowie 14 Tage später wurde die Progesteronkonzentration im Blut bestimmt. Die Ergebnisse zeigen, dass weder Behandlung noch Parität einen Einfluss auf die Brunstraten (Gruppe L 91.7 %, Gruppe K 93.8 %, nulli- und pluripare Schafe 96.9 % bzw. 90.8 %) hatten. Schafe der Gruppe L wiesen für den 1. Zyklus eine tendenziell bessere und insgesamt eine signifikant (P < 0.05) höhere Ablammrate als Tiere der Gruppe K auf (71.7 % vs. 60.4 % und 83.3 % vs. 72.9 %). Pluripare hatten im Vergleich zu nulliparen Auen in Bezug auf die erste Brunst und auch insgesamt höhere (P < 0.05) Ablammraten (75.0 % vs. 46.9 % bzw. 92.1 % vs. 46.9 %) sowie eine grössere (P < 0.05) Anzahl Lämmer pro synchronisierte Aue (1.4 ± 1.0 vs. 0.9 ± 1.1 bzw. 1.7 ± 0.8 vs. 0.9 ± 1.1). Vierzehn Tage nach Entfernung der Spange wurden höhere (P < 0.05) Progesteronwerte bei der Gruppe L als bei der Gruppe K (7.7 ± 4.3 vs. 5.6 ± 2.7 ng/mL) sowie bei nulli- als bei pluriparen Schafen (9.1 ± 5.6 vs. 5.7 ± 2.1 ng/mL) gemessen. Zusammenfassend kann festgehalten werden, dass die Ablammrate nach Langzeit- besser als nach Kurzzeitbehandlung war und nullipare Auen zur Brunstinduktion ausserhalb der Zuchtsaison weniger geeignet waren

Protracted induction of parturition enhances placental maturation, but does not influence incidence of placntal retention in cows

As the etiopathology of retained placenta is still not resolved in cattle, we compared the effects of protracted induction of parturition (PIP) and conventional induction of parturition (SIP) on placental maturation and the occurrence of retained placenta. PIP was induced in 13 cows by administration of 1.3 mg dexamethasone im twice daily between Days 268 and 273 of gestation and 40 mg dexamethasone im on Day 274 of gestation. For SIP, 10 cows received a single injection of 40 mg dexamethasone on Day 274 of gestation. A third group (SPON, n = 11) served as a nontreated control group. Within 2 hours after birth, two placentomes were extracted from the uterus and used for assessment of placental maturation by histology and immunohistochemistry. Incidence of retained placenta was lower (P < 0.05) in group SPON (9%) compared with groups PIP (54%) and SIP (70%). Staining with Masson's trichrome and pan-cytokeratin indicated a higher degree of atrophy and flatness of the maternal crypt epithelium in cows with physiological release of fetal membranes (REL) compared with cows with retained placentae (RET). Staining with anti-caspase-3 ratified the observations as more apoptotic cells were detected in groups SPON and PIP compared with group SIP; however, data were not statistically significant. Additionally, the expressions of the potent vasodilators endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) were evaluated. Both eNOS and iNOS were only expressed in chorionic tissue. Endothelin-1 (ET-1), a major vasoconstrictor, showed positive staining in maternal crypt epithelium and in chorionic epithelium. No differences were found for iNOS and eNOS and ET-1, neither among the experimental groups nor between RET and REL cows. These findings indicate that a PIP results in increased placental maturation, but does not influence the incidence of placental retention in cows. The expression of vasoactive substances does not seem to be related to the placental separation process

Evaluation of bovine luteal blood flow by using color Doppler Ultrasonography

Since luteal vascularization plays a decisive role for the function of the corpus luteum (CL), the investigation of luteal blood flow (LBF) might give valuable information about the physiology and patho-physiology of the CL. To quantify LBF, usually Power mode color Doppler ultrasonography is used. This method detects the number of red blood cells moving through the vessels and shows them as color pixels on the B-mode image of the CL. The area of color pixels is measured with computer-assisted image analysis software and is used as a semiquantitative parameter for the assessment of LBF. Although Power mode is superior for the evaluation of LBF compared to conventional color Doppler ultrasonography, which detects the velocity of blood cells, it is still not sufficiently sensitive to detect the blood flow in the small vessels in the center of the bovine CL. Therefore, blood flow can only be measured in the bigger luteal vessels in the outer edge of the CL. Color Doppler ultrasonographic studies of the bovine estrous cycle have shown that plasma progesterone (P4) concentration can be more reliably predicted by LBF than by luteal size (LS), especially during the CL regression. During the midluteal phase, cows with low P4 level showed smaller CL, but LBF, related to LS, did not differ between cows with low and high P4 levels. In contrast to non-pregnant cows, a significant rise in LBF was observed three weeks after insemination in pregnant cows. However, LBF was not useful for an early pregnancy diagnosis due to high LBF variation among cows. When the effects of an acute systemic inflammation and exogenous hormones on the CL are examined, the LBF determination is more sensitive than LS assessment. In conclusion, color Doppler ultrasonography of the bovine CL provides additional information on luteal function compared to measurements of LS and plasma P4, but its value as a parameter concerning assessment of fertility in cows has to be clarified