گاو شیری

Studying the changes in the concentration of cortisol and thyroid hormones in blood serum is considered an effective step in monitoring the health of animals. The purpose of this study was to investigate the concentration of thyroid hormones and cortisol in Holstein cows two weeks before and two weeks after calving. This research was a quasi-experimental study conducted on 60 three-year-old Holstein cows. The levels of thyroid-stimulating hormone (TSH), thyroxine (T4 and T3), and cortisol were compared in three groups of heifers: one pregnant and two pregnant heifers. The level of T4 hormone after the birth of animals (7.07 ± 3.26 ng/dL) was significantly higher than its level before this event (4.98 ± 1.83 ng/dL). However, T3 and TSH levels were not significantly different before and after parturition. It seems that the concentration of T4 before parturition is lower than the concentration of this hormone after parturitionKeywords: Transition Period, Thyroid, Cortisol, Dairy Cow

The decline in fertility among cows and heifers significantly impacts lactation performance. Estrus synchronization serves as an effective strategy in dairy herds to enhance fertility, resulting in a higher proportion of animals exhibiting estrus within a specified timeframe and subsequently undergoing artificial insemination. This study aimed to evaluate three estrus synchronization techniques, Heatsynch, Ovsynch, and Cosynch, concerning various reproductive parameters in dairy cows experiencing fertility problems and irregular estrus cycles. Four distinct experimental groups were established for this study. Thirty dairy cows with prior fertility issues, including endometritis, and a positive treatment response, were divided into three groups for different estrus synchronization methods. The fourth group included ten repeat breeder cows that did not undergo any synchronization process. In the Heatsynch method, an injection of 25 μg of gonadotropin was administered intramuscularly on day 0, followed by 1 mg of cloprostenol seven days later, and 2 mg of estradiol benzoate on day 8, with artificial insemination occurring 16 hours after. The Ovsynch method involved the initial injection of 25 μg of gonadotropin on day 0, followed by 1 mg of cloprostenol a week later, and an additional 25 μg of gonadotropin on day 9, with insemination occurring 16 hours later. The Cosynch approach mirrored the Ovsynch procedure but required that artificial insemination be conducted immediately after the final injection. Findings indicated that the Heatsynch synchronization method significantly enhanced the estrus and pregnancy rates. Hence, implementing estrus synchronization can effectively boost pregnancy rates in dairy cows encountering fertility challenges.

Infectious and non-infectious claw lesions cause lameness in dairy cows. The primary and main causes of lameness in dairy cows are sole ulcer, hemorrhage and white line disease. The present study was conducted to provide an initial estimation of the occurrence of claw horn lesions in Iranian dairy cows. The study was carried out in four dairy farms with hoof care program (hoof trimming, locomotion scoring, footbath, bedding management, heat stress management, insect control, acidosis control indices, and nutrition) for the past five years. All the relevant data from hoof examinations and trimming between 2012 and 2013 were recorded and extracted. Reports were presented descriptively with mean and standard deviation, and if necessary, statistical comparison was performed using the chi-square test, considering values of P<0.05 as statistically significant. Overall, data from 20,222 cows were examined. White line disease in 2013 (703 cases, equivalent to 7.19% of cows) were higher than 2012 (391 cases, equivalent to 4% of cows), as well as sole ulcer (941 cases, equivalent to 9.63% in 2013 and 816 cases, equivalent to 8.35% in 2012). However, a consistent pattern was not observed regarding toe ulcer. The results of the present study indicate a higher occurrence of sole ulcer and white line disease in autumn.

Brucellosis is one of the most important diseases common to humans and animals worldwide, both economically and publicly. Cattle brucellosis is usually caused by Brucella abortus and is one of the most important diseases in many countries of the world because of its economic importance. Generally, risk factors for brucellosis can be divided into four groups of management factors (herd size, etc.), animal factors (age, sex, etc.), factors divided by rancher (rancher age, etc.) and geographical area (such as weather conditions, etc.). Therefore, this study investigated the relationship between some risk factors of brucellosis at the animal level. This case-control study was performed on 843 cows including 281 seropositive (case) and 562 seronegative (control). Data were analyzed using Stata 14 software and conditional logistic regression. Being pregnant (OR= 0.44), lactating (OR= 0.43) and having a good vaccination history (OR= 0.09) reduced the risk of infection and being born in another farm (coming from another farm) (OR= 2.04) and having a history of abortion (OR= 3.77) increased the risk of brucellosis infection in dairy cows. Appropriate vaccination and no displacement of livestock is recommended.

The purpose of this study is to investigate the role of some serum parameters in the diagnosis of fatty liver in cattle with special attention to its degree and to determine the best cut point of these parameters in order to predict the occurrence of fatty liver. Blood and liver samples of 28 cows were taken at the time of slaughter. Serum concentrations of liver enzymes, bilirubin, protein, and lipid profile were determined and the ratio of blood lipids to HDL was calculated. BCS and age of the cows were also recorded. ROC statistical model was used to determine critical thresholds for fatty liver prediction. As the severity of fatty liver increases, AST, GGT, cholesterol and HDL increases, and these can be used as a biomarker to identify severe and mild fatty liver. Also, the severity of the disease increases as the BCS decreases and age increases. ROC analysis showed that AST, GGT, protein, cholesterol to HDL, BCS and age are suitable for predicting the disease. The best cut-off point for predicting fatty liver was suggested as 55.05 IU/L for AST, 14 U/L for GGT, 6.55 mg/dl for total protein and 3.18 for cholesterol to HDL ratio. The best cut point for BCS and age was 4.25 and 6.5 years, respectively. The result showed that measurement of liver enzymes and lipid profile is of acceptable diagnostic importance in determining the degree of fatty liver in cows in field conditions and can be a suitable method to replace liver biopsy.

In order to determine the sero-epidemiological prevalence of Neospora caninum in Garmsar, in this study, bulk milk samples were prepared for ELISA testing from 72 large herds of dairy cows in Garmsar city (about 10% of all livestock farms in this city). Also, serum samples of 11 dog belonging to herds with positive blood samples were taken and sent to the laboratory to be analyzed by ELISA kit. The findings showed that in 55 farms (75.4%) the results of the ELISA test were positive. In 11 samples taken from herd dogs, positive results were shown in 9 dogs. The geographical region of sampling, livestock population in the herds, parturition to pregnancy interval, pregnancy and the conception did not differ between ELIZA positive and negative herds. (P>0.05). The average number of female calves in the negative ELISA herds was 2 and in positive ELISA was 3 (P=0.01). The mean rate of herd pregnancy in positive ELISA herds was 50% and in negative ELISA herds was 45% (P>0.05). Also, the average milk production per cow was 27.8 kg in negative herds and 26.9 kg in positive herds (P=0.026). The correlation between the presence of dogs and the spread of this parasite was confirmed by Pearson's and Spermman's correlation tests. (P=0.00, r=0.47). It was concluded that in Garmsar city, 75.4% of the bulk milk of the examined herds had a positive ELISA result, and the amount of milk production in these positive herds was less and the presence of dogs was more.

Selenium is an essential element in dairy cattle, particulrarly for reproduction. The present study was conducted in order to determine the amount of selenium in the blood of different groups of cattle in Isfahan province industrial cattle farms and also the effect of season (summer and winter) on its concentration in the form of a randomized complete block design. The present study was investigated the blood selenium level in dairy cattle in Isfahan province. Also, the effect of season (summer and winter) on selenium values was studied. This experiment was carried out in a complete block randomized design for 553 cows in 17 farms from different regions of the Isfahan province. Acordingly, 553 cows were selected from 17 industrial cattle breeding units in different geographical parts of the province. The population of cows in each cattle farm wasere divided into five groups which included high producing cows (n=154), fresh cows (n=118), dry and pregnant heifers (n=121), non-pregnant heifers (n=81) and calves. Blood selenium concentration was indirectly assessed determined through the measurement of glutathione peroxidase activity by Alpha Classic Auto Analyzer. According to the results, the mean whole blood selenium concentration mean for high producing cows, fresh cows, dry and pregnant heifers, non-pregnant heifers and calves were measured at 0.21, 0.18, 0.24, 0.24, 0.21 mg/L, respectively. Dry and pregnant heifers and non-pregnant heifers with higher selenium concentration showed significant differences compared to other groups (P<0.05). The lowest selenium concentration was significantly observed for fresh cows (P<0.05). No significant differences were found among different groups of dairy cows in terms of peroxidase enzyme activity for glutathione peroxidase activity. The mean blood selenium concentrations in summer and winter with no significant differences were at 0.21± 0.08  (n=129) and 0.20±0.06  (n=174) mg/L, respectively which showed no significant effect of season on blood selenium level. Also, the comparison of the same group in different farms showed significant difference in terms of blood selenium levels s between them (P<0.05).Therefore, it is recommended to check the blood selenium level of dairy cattle and then ,use a selenium supplement under supervision of animal nutritionists.

Injuries of the birth canal in cows (perineal lacerations, fistula…) cause significant economic loss in dairy herds. These injuries usually are associated with obstetric trauma during labor. Third degree perineal lacerations and fistula formation usually happen because of dystocia, improper repairs, abscesses and forced extractions and lead to fecal contamination of the birth canal and reduced fertility. The main reason for the birth canal and external part of the reproductive tract surgery is to restore fertility of the animal and repair the injuries associated with dystocia. In this review the causes, management, and treatment of these disorders by emphasizing on the importance of birth canal injuries in cows were discussed.

The objective of the present study was to evaluate e the reproductive performance following the treatment protocols for ovarian follicular cysts according to the status of endometritis in dairy cows.. A total of 94 dairy cows with ovarian follicular cysts with considering the condition of endometritis were randomly divided into three treatment groups: Group 1: Control group did not receive any treatment, Group 2 that received 200 µg Gonaderoline plus 500 µg Cloprostenol and Group 3 that received the same hormone therapy plus aspiration of ovarian follicular cysts. The response to treatment of ovarian follicular cyst, reproductive performance of cows with, without endometritis and total cows was statistically analyzed using the SPSS software. A higher percentage (68.9%) of cows with ovarian cysts had endometritis. The percentage of cows that respond to treatment of ovarian follicular cyst was significantly higher in cows of with endometritis and total cows in hormonal applications plus cyst aspiration group (87.5% and 82.6%, respectively) compared to control (42.9% P= 0.02 and 46.2%, P= 0.02 respectively) and only hormonal applications (52.5% P= 0.01 and 59.6%, P= 0.04 respectively) groups, but no statistically significant differences were found in reproductive performance among the treatment groups. According to our results, the presence of endometritis at the same time as ovarian cysts has no significant negative effect on the treatment of ovarian follicular cysts in cow and the treatment of cyst with treatment of follicular cysts with hormonal applications plus cyst aspiration method can be used successfully in different endometritis conditions.

Mastitis could be diagnosed by diverse methods, including physical, clinical, and laboratory tests. The present study aimed to evaluate the accuracy of subclinical mastitis diagnosis using enzymatic diagnostic tests for milk lactate dehydrogenase (LDH) and alkaline phosphatase (ALP). This study was performed on 90 Holstein cows selected randomly out of high- and low-yielding dairy cattle. According to the result of the California Mastitis Test, two milk samples were obtained from the intended udder quarters based on the principles of the National Mastitis Council. One specimen was used for microbial culture and the other one was utilized for somatic cell count (SCC), as well as milk LDH and ALP tests by diagnostic kits. Considering microbial culture as the gold standard for subclinical mastitis diagnosis, the sensitivity of SCC, ALP, and LDH tests was 87%, 59.3%, and 70.4%, respectively. Moreover, the specificity of these tests was 77.8%, 80.6%, and 77.8%, respectively. Our findings revealed a strong correlation between SCC, LDH, and ALP. It was observed that an increase in SCC was accompanied by augmented LDH response. According to the results of the present study, SCC was the most efficient test for diagnosing subclinical mastitis in dairy cows, followed by LDH and ALP.

Neosporosis is the main cause of abortion in cattle in Iran and other parts of the world, which is caused by a parasitic protozoan Neospora caninum . The economic effects of Neosporosis are reduced milk and meat production in cattle. Transmission of N.caninum is possible through vertical and horizontal routes. Some studies have been conducted on the importance of vertical transmission during infancy, through colostrum and milk. Most studies in Iran to investigate the incidence of N.caninum in cattle are based on the search for anti-parasitic antibodies in the blood serum and limited studies have been performed on milk. The aim of this study was to investigate the presence of N.caninum genome in raw cow milk using PCR method to evaluate the vertical transmission of this parasite. In this study, 300 samples of raw cow's milk were collected from traditional farms in Yazd province. The results of this study showed that 54 cases (18%) of 300 samples of cow milk were infected with N.caninum genome. The findings of the present study indicate a high presence of N.caninum infection and showed that infected cow's milk plays an important role in the transmission of Neosporosis in newborn calves. Based on these findings, control and eradication programs, including vaccination, are necessary to prevent and reduce the economic losses of this protozoan infection in cattle.

Hoof trimming as a part of hoof health management is one of the important parts of herd health management system. Timing of hoof trimming and its method are the main subjects that must be known for an efficient hoof trimming program. In the current study, the different suggested timings of trimming (around drying, early, middle and end of lactation) have been reviewed. Although the need for more research to find the best time for hoof trimming is yet necessary, an appropriate timing is suggested based on the current literature. Also the unique role of accurate data recording system in time management of trimming is mentioned.

Lameness is one the most important problems in dairy herds and a major cause of financial loss and pain and discomfort to animals. Different surveys have revealed that most lameness causing lesions in cattle originate in the claw and in order to better understand the claw disorders, one has to have good understanding of the anatomic structure, horn characteristics, and biomechanics of the claw. The claw is a direct product of the underlying living tissue and different factors affect the rate of horn growth and wear. Here, we aim to review the different factors effecting the horn growth and wear, weight bearing, and biomechanics of the claw.

Mastitis, as one of the most important diseases in cattle, is the cause of the greatest economic loss in the dairy industry. The occurrence of mastitis is associated with the development of immune responses and an increase in the level of reactive oxygen species (ROS). The production of high amounts of ROS and the lack of optimal amounts of antioxidant compounds are associated with oxidative stress. The aim of this study was to evaluate the status of oxidative stress indices in cows with clinical mastitis. In this study, two groups of cows were studied: healthy cows and cows with clinical mastitis. The body condition score (BCS) of the cows was assessed at the time of blood sampling. Total antioxidant capacity and selenium concentration were significantly higher in healthy cows than sick cows. Healthy cows had lower malondialdehyde concentrations than sick cows, although this difference was not statistically significant. When the cows were divided into three groups according to body score, the amount of glutathione peroxidase in cows with high body scores was significantly lower than the other two groups. The amount of malondialdehyde and the number of milk somatic cells in cows with high and moderate body scores were significantly higher than the other group. The results show that there are changes in the antioxidant defense of cows with mastitis that lead to oxidative damage, so the use of antioxidants is necessary to control mastitis. Obese cows are also more sensitive to oxidative stress.

Today, the most important factor in the occurrence of metabolic and reproductive diseases in dairy cattle is the disturbance of natural process in the body’s cellular-molecular events that occurs after increasing of oxidants and the formation of oxidative stress. Ketosis is one of the most important metabolic abnormalities caused by disruption of energy metabolism early in lactation. This study was carried out on 45 Holstein dairy cows (between 3 and 5) and high-yielding dairy farms of Isfahan province. Blood samples of each cow were taken 21-27 days after Parturition and serum samples were obtained. BHBA, catalase and superoxide dismutase, were measured. Ovulation synchronization protocol was performed for all cows after the Clean Test and confirmation of genital health by B-mode ultrasound. The first Artificial Insemination was performed at 45-50 days postpartum and at the same time, follicular diameter, ovarian status, and uterine tonicity were assessed by using rectal ultrasonography. Also, the presence or absence of estrus was recorded in all cows. At 32 days after artificial insemination, the cows were pregnancy diagnosed by rectal ultrasound. The results of the present study showed that the concentration of superoxide dismutase (P=0.04) and catalase (P=0.08) decreased in subclinical ketosis dairy cows compared to healthy cows, Also, BHBA concentration was lower significantly in pregnant cows than nonpregnant (P = 0.008). Finally, the results of this study confirm that oxidative stress biomarkers can be promising biomarkers for the prediction of subclinical ketosis in postpartum dairy cows.