The protective effectiveness of an inactivated bovine ephemeral fever virus vaccine.

Bovine ephemeral fever (BEF) is an important viral disease of cattle. Despite the extensive use of inactivated vaccines for the prevention of BEF, a controlled study of their field effectiveness has never been performed. We conducted a large field effectiveness study of a BEF inactivated vaccine, during a large BEF outbreak. Neutralizing antibody titers measured in 385 heifers and calves 1 month after 2(nd) vaccination averaged 1:91.8 (CI95%=76.6-110). The effectiveness study enrolled 2780 cows in nine herds. In two herds cows vaccinated twice, 1 year before the outbreak and once 2-3 months before outbreak onset were compared with non-vaccinated cows. Average vaccine effectiveness of three vaccine doses compared to no vaccination was 47% (CI95%=34-57) in these herds. In two other herds cows vaccinated twice 1 year before the outbreak and twice again 2-3 months before outbreak were compared with cows vaccinated only twice 2-3 months prior to the outbreak. Average vaccine effectiveness of four doses compared to two doses was 49% (CI95%=25-65) in these herds. In five herds cows vaccinated twice 2-3 months before outbreak onset were compared with non-vaccinated cows. This vaccination schedule was shown to be non-effective (average effectiveness=2%, CI95%=-14-17). Milk production analysis on one of the effected herds, in which 56% vaccine effectiveness and an absolute reduction of 27% in morbidity were documented, revealed a net milk production loss of 175.9kg/sick cow (CI95%=127.9-223.9) and an average gain of 37kg for each vaccinated cow (CI95%=-3.6-77.7). This study indicates that despite the fact that two vaccine doses of the tested inactivated vaccine elicited high titers of neutralizing antibodies, partial protection was induced only when at least 3 doses were administrated before natural challenge.

Acute maduramicin toxicosis in pregnant gilts.

Ionophores are used as feed additives for the control of coccidiosis and growth promotion in farm animals. Reports of maduramicin toxicosis in farm animals are scarce. The present work describes an acute maduramicin toxicosis affecting 22 pregnant gilts, 2 pregnant sows and 2 boars, resulting in a total mortality of 65% within 2days. The clinical and histopathological findings observed shared similar characteristics to acute ionophore toxicosis in pigs, being characterized by severe myodegeneration in skeletal muscle and degenerative changes in the myocardium. Important clinical pathology indices found were elevated levels of CPK and ALT. In contrast to the pregnant gilts, the two pregnant sows completely recovered after 1month and farrowed 2months after the intoxication event healthy piglets. The lack of effect of maduramicin on the fetuses might be indicative of poor placental penetration of maduramicin. Moreover, the present work reports for the first time maduramicin levels in livers (0.5mg/kg) of gilts exposed to lethal concentrations of maduramicin (18.5mg/kg) in the feed. As the average feed intake of the gilts was estimated to be 3.5kg feed/day, the mean maduramicin intake leading to the observed high mortality rate was 0.4mg/kg body weight/day.

Comparison of the epidemiology of epizootic haemorrhagic disease and bluetongue viruses in dairy cattle in Israel.

An outbreak of epizootic haemorrhagic disease virus (EHDV) in cattle in Israel in 2006 enabled a comparison of the spatial distribution of epidemic exposure to EHDV with that of exposure to bluetongue virus (BTV), which is endemic in the country. The seroprevalence of both viruses was examined in 1650 serum samples collected from 139 farms representative of the spatial distribution of dairy cattle in Israel. A significant association between exposure to EHDV and BTV was demonstrated in both univariate and multivariate analyses. Recent exposure to BTV and EHDV (demonstrated by seroprevalence in calves) was clustered in different geographical locations, indicating that the two viruses had different patterns of spread, that of EHDV being influenced by winds and terrain barriers and that of BTV by herd immunity.

The association of winds with the spread of EHDV in dairy cattle in Israel during an outbreak in 2006.

Winds may play a major role in spread of arthropod-borne viruses (arboviruses). Arboviruses like epizootic hemorrhagic disease virus (EHDV), bluetongue virus and bovine ephemeral fever virus (BEFV) frequently cause major outbreaks in Israel with a unique pattern of spread. Most of these outbreaks begin in the Jordan valley, near the Sea of Galilee and then spread to the north, south and west through the major valleys of Israel. The aim of this study was to describe the spread pattern in such an outbreak and to find if this pattern can be explained by winds. Herein, we compared the spread rate to each direction and used Cox proportional hazards model to test factors associated with the spread of EHDV, which emerged in diary cattle in Israel during the summer of 2006. Documented, clinical and serological data on spread of the outbreak were then compared with wind data collected by meteorological stations along the trail of virus spread and with modeled winds at high altitude (>500 m). The analysis revealed that both the hazard and the rate of outbreak spread to the south and to the north were significantly higher than to the west. Average rate of outbreak spread during periods in which at least 3 h of winds to spread direction were recorded was 20,880 m/week (SD=13,230) vs. 7486 m/week (SD=4936) in periods during which no such winds were recorded. Serological evidence demonstrated exposure to the virus up to 166 km away from the location of the initial outbreak center. Modeled wind data showed that this spread may be explained by winds at high altitudes. Animal movements due to shipments of feedlot calves and slaughters could not explain the spread pattern observed during the outbreak. This study therefore shows that winds are probably a major contributory factor for long and medium distance spread of Culicoides borne viruses in this region.

Factors affecting fertility of dairy cows in Israel.

UNLABELLED: The objectives of this review are to describe the reproductive parameters monitored in Israeli dairy herds and to evaluate their changes in recent years. Eighty percent of the cows and 70% of the farms use the Israel Cattle Breeders' Association Herdbook and about 50% of them use pedometry systems. Intensive herd medicine is practiced in 80% of the herds by Hachaklait Veterinary Services Ltd. Herd-health reports monitor calving, production and reproduction. Causal analysis explains the effects and interactions of various risk factors involved. The average of 305 days of milk production per cow increased between 2004 and 2008 from 11,200 to 11,903 kg. At the same time the first A.I. conception rate (C.R) dropped from 43.0 to 40.7% and from 35.6 to 30.5% in primiparous cows (PC) and multiparous cows (MC), respectively. The waiting period (WP) was shortened from 106.2 to 93.4 days in PC and from 99.9 to 87.3 days in MC. The undetected heat rate per herd increased from 30.3 to 38.9% and from 33.9 to 43.9% in PC and MC, respectively. The average of days open per herd dropped from 127 to 118.4 and from 127.5 to 120.5 in PC and MC, respectively. The rate of cows open by 150 days in lactation dropped from 42% (+/- 10.2) to 34.2% (+/- 8.1) and 47.1% (+/- 8.8) to 39.5% (+/- 7.1) in PC and MC, respectively. The ratio between summer inseminations and winter inseminations increased from 0.81 to 1.04 from 2000 to 2008. The calving interval (CI) average fluctuated around 424.5 (+/- 2.0) days and 417.5 (+/- 1.7) days in PC and MC, respectively. The average duration of the dry period in 2008 was 60.7 (+/- 4.7, 47-72) days. From 2004 to 2008, the average herd rate of endometritis increased from 38.1 to 46.0% and from 25.5 to 30.1% in PC and MC, respectively. The milk fat to protein ratio in the first test day of lactation has remained steady during the past 5 years. Genetic trends in the breeding values of fertility and milk showed consistent improvement from 2000 to 2006. CONCLUSIONS: In recent years there has been a small decline in some reproductive parameters, while at the same time others have remained unchanged. The farmer's economical viewpoint and management practices have contributed to the changes.

Management of heat stress to improve fertility in dairy cows in Israel.

Israel has about 100,000 dairy cows mostly all of Israeli-Holstein-breed, kept in close to 1000 dairy farms. Most farms are distributed along the Mediterranean Sea coast and in the hot internal valleys. According to the Israeli Herd book the average annual milk production, per cow in 2008 was 11,460 kg, with 3.7% fat and 3.2% protein. Israel's climate is considered "subtropical dry" or Mediterranean, characterized by warm and dry summer with day temperatures above 30 C and relative humidity ranging from 50 to 90%. Climatic limitations brought dairy farmers to develop and implement new technologies and management practices that would enable high milk production and reproduction in summers. In the last three decades the Ministry of Agriculture research units, the extension service and dairy farmers conducted a series of trials and surveys in order to develop an efficient cooling system that will obtain and maintain high milk yield and good reproduction during the hot and humid summer. The cooling system commonly used in Israel is based on a combination of frequent direct watering of the cows, followed by forced ventilation air blowing onto the cows. The system was developed in Israel nearly 30 years ago. A typical cycle is five minutes long and consists of 30 sec of watering followed by 4.5 min of forced ventilation. Providing the cows with 5-7 cooling sessions per day, 30-45 min each, allowed cows, producing 25-30 kg of milk per day to maintain their body temperature below 39.0 C, throughout the day time, on a typical Israeli summer day. At the same time, non-cooled cows had high body temperatures (above 39.5 C), during some part of the daytime and returned to normal body temperatures (below 39.0 C), only for a few hours late at night. In an experiment conducted in 1985-86, conception rate (CR) of cows, cooled as described above, was significantly higher than of non-cooled cows (59 vs. 17% and 57 vs. 17%), for first insemination and for all inseminations, respectively. Pregnancy rate (the amount of pregnant cows out of the eligible cows in the herd) calculated for 90, 120 and 150 days after calving differed significantly between the groups, (44, 59 and 73% vs., 5, 11 and 11%), in cooled and non-cooled cows, respectively. CR and pregnancy rates obtained in intensively cooled herds in this experiment were similar to those obtained during the winter of that year, in commercial dairy farms in Israel. Differently from the results described above, when cows in summer were intensively cooled, only for a period of 2 days before and 8 days after A.I, CR failed to improve (31 and 36%), in cooled and non-cooled cows, respectively. These results offer a conclusion that cows must be intensively cooled and must maintain normal body temperatures during the entire day and during the whole summer. i.e. the entire reproductive process from follicular development until implantation of the embryo in the uterus, in order to express cow's full reproductive potential in Israeli summer conditions. The effect of cooling intensity on cow's productive and reproductive traits was studied in a wide survey, during four consecutive years (1998-2001), on 14 farms, averaging 300 milking cows each, all located in the coastal plain of Israel. Farms were categorized into three different groups according to the intensity of summer cooling. "Intensive" (7.5 cumulative cooling hours per day), "Moderate" (4.5 cumulative hours per day) and "No-cooling" at all. CR was 56, 53 and 54%, and 40, 34 and 15%, for primiparous (P < 0.01) and 47, 46 and 43%, and 34, 34 and 17% for multiparous cows (P < 0.01), in the "intensive", "moderate", and "no cooling" groups, in winter and summer, respectively. In another survey based on the Israeli Herd Book data from 2005, using elite yielding herds (with average annual milk production per cow of more than 13,000 kg), the average CR of intensive cooled herds was 39 and 19%, in winter and summer respectively, compared to 39 and 12%, respectively, in non-cooled high yielding herds (P < 0.01). This indicates that intensive cooling in summer can reduce by half the summer drop in CR, even in very high yielding herds. The Ministry of Agriculture extension service, in cooperation with the Israel Cattle Breeders Association (ICBA), developed a computerized report called "Summer to Winter (S:W) Performance Ratio", based on the "Israeli Herd book" data from more than 300 herds. The higher the ratio is for productive and reproductive traits, the better a farm handles summer negative effects on cow's performance. Based on the S:W ratio of each herd in 2007, we quantified the overall effect of intensive cooling in summer on the cow's whole year performance. Data from 24 farms with the highest S:W ratio were compared with data from 24 farms with the lowest S:W ratio. The comparison showed that well cooled cows in Israeli summer added approximately 700 kg of milk to cow's lactation, an increase of 6.5% in its annual production. Summer CR were significantly higher in the highest S:W ratio farms, compared with the lowest ones (27 vs. 19%), and compared to those obtained in same groups in winter (40 vs. 36%), respectively. High S: W ratio herds reached in summer conception rate of 70% of their winter CR, compared to only 50% in the lowest S:W ratio farms inseminated in same period. Trials conducted in the last 10 years show clearly that intensive cooling of high yielding cows (above 45 kg daily) in summer cannot completely eliminate summer decline in CR (as was achieved two decades ago when daily production was less than 30 kg). These high yielding cows despite being intensively cooled could not maintain normal body temperature all day long. This fact brought Israeli researchers to look for hormonal treatments to improve cow's summer fertility, among them elevating post insemination blood progesterone, GnRH treatment at time of insemination to optimise insemination time, improvement of egg quality by elimination of aged follicles produced during heat stress and the use of timed AI and embryo transfer. Part of these treatments improved summer CR when combined with intensive cooling. Cooling Intensification combined with hormonal therapy, management and nutritional practices are expected to minimize the gap between summer and winter CR obtained in Israel in the future.

The use of pedometry for estrus detection in dairy cows in Israel.

The objectives of this review are to describe the use of pedometry on commercial dairy farms in Israel, to evaluate its efficiency in heat detection and to describe a clinical trial comparing between pedometry and the Ovsynch technique. Pedometry is the major tool of heat detection on most farms in Israel today. On many farms automated electronic pedometry is the sole mean of heat detection. Production and reproduction parameters are monitored by Hachaklait Veterinary Services Ltd. Results are compared with the farm history and with national means and goals. The average herd rate of undetected heat in more than 120 herds recorded between 2004 and 2008 has increased from 30.3 to 38.9% in primiparous cows and from 33.9 to 43.9% in multiparous cows respectively. The average duration of the waiting period has dropped from 106.2 to 93.4 days and from 99.9 to 87.3 days in primiparous and multiparous cows respectively. The average annual rate of cows shown on heat by pedometry and not inseminated by the A.I. technicians in recent years was 13% and remained steady. The mean herd rate of normal length heat cycles (18-24 days) in multiparous cows in recent years has been fairly steady; 57.4 to 58.4% of all cycles detected in 2004 and 2008 respectively. Herd rate of double cycles is also used to estimate the sensitivity of pedometry systems. Average rate of double cycles (37-60 days) per herd per annum in multiparous cows has dropped steadily from 22.6 to 20.1% between 2004 and 2008 respectively. Mean herd rate of short cycles in multiparous cows in 2008 was 7.4% Pregnancy checks are performed by the herds' veterinarians by transrectal palpation from 40 days post A.I. onward. In 2008 the average herd rate of negative pregnancy checks in cows was 27.5% (9.5-53.4%). The wide range indicates a large variability of pedometry system in tracking non-conceived cycling cows. Beside activity and heat detection pedometry systems record other individual cow parameters. A controlled field trial comparing between pedometry, observation and Ovsynch did not yield significant differences in reproductive measures.