L'estrès per calor influeix en la fertilitat de les vaques lleteres

Patir condicions de temperatura superiors a la zona de confort tèrmic -el que es coneix com estrès per calor- és un dels principals factors relacionats amb la pèrdua de fertilitat de les vaques lleteres, especialment en zones amb estius calorosos, com Catalunya. Així ho conclou un estudi dut a terme a granges de vaques lleteres de Lleida i Osca per un grup d'investigadors de la Universitat de Lleida i de la Universitat Autònoma de Barcelona. Els científics han analitzat les dades de 10.964 inseminacions artificials realitzades a 4 ramats en relació a diverses variables climàtiques registrades al llarg de 3 anys.Sufrir condiciones de temperatura superiores a la zona de confort térmico -lo que se conoce como estrés por calor- es uno de los principales factores relacionados con la pérdida de fertilidad de las vacas lecheras, especialmente en zonas con veranos calurosos, como Cataluña. Así lo concluye un estudio realizado en granjas de vacas lecheras de Lleida y Huesca por un grupo de investigadores de la Universitat de Lleida y de la Universitat Autònoma de Barcelona. Los científicos han analizado los datos de 10.964 inseminaciones artificiales realizadas a 4 rebaños en relación con diversas variables climáticas registradas a lo largo de 3 años.Summer heat stress is a main factor related to low conception rates in high producing dairy herds in warm areas worldwide. A research group of UAB Faculty of Veterinary Medicine has studied the impact of several climate variables on conception rates in high producing dairy cows in northeastern Spain by examining 10,964 inseminations

Serological and shedding patterns after Coxiella burnetii vaccination in the third gestation trimester in dairy cows

This study sought to assess the effects of an inactivated phase I vaccine against Coxiella burnetii at the start of the third trimester of gestation on serological profiles, bacterial shedding patterns and subsequent reproductive performance in dairy cows. Cows were randomly assigned to a control (n = 78) or a vaccinated (n = 78) group on days 171–177 of gestation. Samples of placenta and colostrums at parturition, vaginal fluid, faeces, milk (PCR identification) and blood (anti-C. burnetii antibody detection) were obtained on the day of treatment and on days 91–97 post partum, and also on parturition day and weekly on days 1–7, 8–14, 15–21, 22–28 and 29–35 post partum in a subset of 70 animals. By Kaplan-Meier survival analysis, no significant effect of vaccination was detected on any of the reproductive variables studied. According to the odds ratio, C. burnetii shedding on days 171–177 of gestation was highly correlated with seropositivity against C. burnetii (OR = 9.1), while vaccination was not linked to reduced shedding of the bacterium. In shedders compared to others, the likelihood of pregnancy to first AI decreased and increased by factors of 0.26 and 16.1 on days 1–35 and 91–97 post partum, respectively. In conclusion, when administered at the start of the third trimester of pregnancy, the inactivated C. burnetii phase I vaccine failed to reduce bacterial shedding

Effects of long-term vaccination against Coxiella burnetii on the fertility of high-producing dairy cows

The impact of long-term vaccination against Coxiella burnetii on the fertility of cows was studied. Double vaccinations three weeks apart at the start of the third trimester of gestation in each of two consecutive pregnancies were applied. The final study population consisted of 410 cows after the first vaccination round. Based on the odds ratios, the likelihood of early fetal loss (pregnancy loss following a positive pregnancy diagnosis before Day 90 of gestation) was higher in control cows (OR = 1.42) than in vaccinated cows. The final study population consisted of 336 cows after the second round of vaccination. According to the odds ratios, vaccinated C. burnetii seronegative cows were less likely to be subfertile (> 3 AI) (OR = 0.4) compared to non-vaccinated seronegative animals, and the likelihood of early fetal loss was lower in vaccinated C. burnetii seropositive animals (OR = 0.3) compared to non-vaccinated seronegative cows. Seropositivity to C. burnetii was positively related to twin pregnancy after the two rounds of vaccination (OR = 2.1 and 3.5, respectively). These results indicate that two consecutive vaccination rounds against C. burnetii in advanced gestation reduce subfertility and early fetal loss in dairy cows

Coxiella burnetii antibody dynamics in heifers born to vaccinated versus non-vaccinated dams in a chronically infected dairy herd

This study was designed to compare Coxiella burnetii antibody dynamics in heifers born to vaccinated or non-vaccinated dams in a single high-producing dairy herd chronically infected with the bacterium. Antibody dynamics were examined from birth to the postpartum period in replacement heifers (n = 14) born to non-vaccinated dams (n = 7) or to dams that had been vaccinated on gestation days 171–177 (n = 7) and 192–198. Samples of blood, milk, faeces, vaginal fluid, colostrum and cotyledons (the latter two only at parturition) were obtained in the dams over the period from gestation days 171–177 to postpartum days 91–97. Blood samples were used to detect antibodies against C. burnetii and remaining samples for PCR identification of the bacterium. In their calves/heifers, blood samples for antibody determinations were collected from birth to postpartum at the time points 1–7 and 22–28 days and 3, 6 and 12 months of age; 90–96 and 210–216 days of gestation; and 22–28 days postpartum. All calves were born seronegative for C. burnetii. Irrespective of the shedding status of their mothers (7 were C. burnetii shedders), seroconversion occurred after colostrum intake in all calves born to seropositive cows (n = 9) and in two of three vaccinated seronegative dams. Thereafter antibody titres gradually declined and by 6 months of age all calves were seronegative. Seronegativity persisted until their first postpartum period. These findings indicate that cows vaccinated during advanced pregnancy transfer immunity to their calves via the colostrum. Maternal C. burnetii antibodies in calves persisted for three months in calves born both to seronegative vaccinated and seropositive dams

Twin Pregnancies in Dairy Cattle: Observations in a Large Herd of Holstein-Friesian Dairy Cows.

Multiple pregnancies have devastating consequences on the herd economy of dairy cattle. This observational study examines incidence patterns based on data from the ultrasonographic examination of 1130 multiple pregnancies in cows in their third lactation or more carrying twins (98.8%), triplets (1.1%), or quadruplets (0.08%), and 3160 of their peers carrying singletons. Cows became pregnant following a spontaneous estrus with no previous hormone treatments. Irrespective of a significant decrease (p < 0.0001) in the conception rate (28-34 days post-insemination) during the warm period of the year, the multiple pregnancy rate was similar for both warm (26.5%) and cool (26.3%) periods. The incidence of unilateral multiple pregnancies (all embryos in the same uterine horn) was higher than that of bilateral pregnancies (at least one embryo in each uterine horn): 54.4% versus 45.6% (p < 0.0001). This difference rose to 17% during the warm season (p = 0.03). Pregnancy was monitored in unilateral multiple pregnancies until abortion or parturition (n = 615). In the warm period, the parturition rate was 43% compared to 61% recorded in the cool period (p < 0.0001). Thus, a warm climate is the main factor compromising the fate of multiple pregnancies. Some clinical suggestions are provided

Interacción genotipo x tipo de dosis de inseminación artificial para la fertilidad del macho de conejo

El objetivo de este trabajo fue estimar los parámetros genéticos de la fertilidad tras la IA con 3 tipos de dosis obtenidas de eyaculados de machos de la línea Caldes: 1) tipo 10: con 10 x 106 espermatozoides/ml y 24h de conservación en un diluyente comercial tipo A. 2) tipo 40: con 40 x 106 espermatozoides/ml y las mismas condiciones de conservación que las del tipo 10. 3) tipo X: dosis preparadas tras diluir los eyaculados con un diluyente comercial tipo B (1:5) siendo desconocida la concentración y sin periodo de conservación. Se realizaron 3,628 IA con dosis del tipo 10 sobre hembras cruzadas, 3,027 con dosis del tipo 40 y la misma población de hembras, y 5,779 con dosis del tipo X sobre hembras puras de la línea Caldes. La fertilidad tras la IA con dosis del tipo 10 (F10), 40 (F40) y X (FX) fue considerada un carácter distinto en cada caso, de tipo binario. Los datos se analizaron utilizando un modelo umbral tri-carácter. La estima de la media de la distribución marginal posterior (DMP) de F10 menos F40 fue de -0.13. Este resultado indica un claro efecto de la concentración sobre la fertilidad, que podría no ser lineal. Las medias de la DMP de F10 menos FX y F40 menos FX fueron -0.37 y -0.23, respectivamente, lo que indica que el efecto de las condiciones de conservación sobre la fertilidad podría ser más importante que el de la concentración ya que FX fue muy próxima a la fertilidad tras la MN y la concentración del tipo de dosis X sería en promedio de unos 50 x 106 espermatozoides/ml. Las heredabilidades parecen ser similares para F10 y F40 y ambas mayores que las correspondientes a la fertilidad tras la MN y a FX. La interacción del genotipo x concentración de la dosis de IA es prácticamente despreciable debido a que las varianzas genéticas fueron similares para F10 y F40 y a que su correlación genética fue próxima a 1. Sin embargo, la interacción podría ser de mayor importancia entre el genotipo y las condiciones de conservación

Is twin pregnancy, calving and pregnancy loss predictable by serum pregnancy-specific protein B (PSPB) concentration 28–35 days after ai in dairy cows?

Double ovulation occurs more frequently in multiparous cows with high milk production than in primiparous cows and the rate of twin pregnancy/calving is increasing worldwide. Diagnosis of twin pregnancy is possible by ultrasound at the time of early pregnancy examination [28–34 days after artificial insemination (AI)]. Pregnancy proteins are also well-known indicators of gestation. The risk of pregnancy loss during the first trimester of gestation for cows carrying twins is three to nine times higher than for cows carrying singletons. Pregnancy-specific protein B (PSPB) is a good indicator not only of pregnancy but also of pregnancy loss. The aims of this study were (a) to collect calving data in some Hungarian Holstein-Friesian herds (n = 7,300) to compare PSPB serum concentrations (measured 29–35 days post insemination) in twin- and singleton-calving cows (Trial 1), and (b) to check the predictive value of PSPB serum concentration for twin pregnancy and pregnancy loss in high-producing Spanish Holstein-Friesian cows (n = 98; Trial 2). Our results showed almost 7% twin calving rate. Although hormonal treatments are commonly believed to be major causes of twin pregnancies, our data do not support this hypothesis. The only exception is the single PGF injection, which significantly increased twin calving. No effect of milk production on the risk of twin pregnancy was found, and twin pregnancy increased with parity. The AI bull, the bull’s sire, the bull’s grandfather and the cow’s father also affected twin calving (P ≤ 0.02). We found much higher frequency of twin calving in cows diagnosed pregnant with higher than 3 ng/ml serum PSPB concentrations at 29–35 days after insemination. In Trial 2, non-significant but well-marked differences were found in PSPB serum concentration between singleton- and twin-pregnant cow samples (2.1 and 2.9 ng/ml) at different bleeding times. Probably the small size of the study population and the effects of milk production on PSPB values may explain this lack of significance

Serological evidence of Coxiella burnetii infection in beef cattle in Queensland

Background Queensland has the highest incidence of Q fever in Australia. The aim of this study was to undertake a cross-sectional seroprevalence survey of Coxiella burnetii, the causative agent of Q fever, in beef cattle in Queensland. Methods Serum samples were tested by ELISA for both phase II and phase I antigens of the organism using an Australian isolate. Blood samples were collected at an abattoir that processes beef cattle originating from northern and north-western Queensland, in addition to blood samples taken from beef cattle across Queensland as part of a second survey. Results Seropositivity was 16.8% (95% confidence interval 16.7-16.8%). Conclusion Evidence of C. burnetii infection in beef cattle has public health implications for occupational exposure of primary producers and veterinarians and for the proximity of beef cattle properties to residential areas in regional Queensland. This study is the first known investigation of C. burnetii seroprevalence in beef cattle in Queensland and the first known use of an Australian C. burnetii isolate for screening using both phase II and phase I antigens. © 2011 James Cook University. Australian Veterinary Journa