ObjectivesThe objective of the present study was to evaluate the pattern of genetic expression of vitamin D receptor (VDR), 1 alpha-hydroxylase (1α-OHase) enzyme and chemokine regulated on activation normal T-cell expressed and secreted (RANTES) in peripheral blood of Holstein dairy cows during transition period.MethodsBlood samples were collected from 16 Holstein dairy cows at 3 weeks prior expected date of delivery (EDD), at the day of parturition, and 3 weeks post-partum for assessment of expression profile of studied genes using real-time PCR and measurement of glucose, ionized calcium (Ca), parathyroid hormone (PTH), inorganic phosphorous (P), sodium (Na), potassium (K), chloride (Cl), and magnesium (Mg) levels.ResultsCompared with 3 weeks prior EDD, VDR gene expression decreased significantly at the day of parturition then increased significantly at 3 weeks post-partum. The genetic expression of 1α-OHase enzyme as well as PTH, K, Na and Cl levels increased significantly at the day of parturition. The Ca level decreased significantly at the day of parturition then increased significantly at 3 weeks post-partum. The P level increased significantly at the day of parturition then decreased significantly at 3 weeks post-partum. Glucose level decreased significantly at the day of parturition and at 3 weeks post-partum. RANTES gene expression showed non-significant changes among the three different time points. The expression of VDR gene had a negative correlation with the expression of 1α-OHase enzyme gene, and serum levels of glucose, PTH, P and K, but had a positive correlation with the serum Ca level. The expression of 1α-OHase enzyme gene had a positive correlation with serum levels of PTH, P and K, but had a negative correlation with the serum Ca level.ConclusionsResults of the current study indicate the importance of monitoring the genetic expression of VDR and 1α-OHase enzyme as indicators of metabolic changes during transition period, suggesting that they are candidate genes to judge the health status of dairy cows during such period.

Objective: To identify the most prevalent diseases of transition period in dairy cows and to highlight on risk factors supposed to play a crucial role in the prevalence of hypocalcaemia. Design: Case-control study Animals: 179 transition dairy cows belonged to five farms. Procedures: Clinical examination and serum analyses were the key to diagnose the transition disorders in the investigated cows. Cutoff points for serum analytes (Ca, Ph, Mg, PTH, glucose, K, Na and Cl) were set. A questionnaire was constructed to identify the possible risk factors associated with hypocalcaemia on both farm level and cow level. Results: Frequency test revealed the prevalence of hypocalcaemia to be (48.04%), hypophosphatemia (40.22%), hypomagnesaemia (33.52%) hypoglycemia (29.05%), hypokalemia (58.1%), clinical ketosis (5.59%) and abomasal displacement (1.12%). Moreover, prevalence of post parturient septic metritis was (26.81%), retained placenta (23.46%) and clinical mastitis was (18.99%). Generally, hypocalcaemia was significantly associated with other concurrent diseases (P ≤ 0.05). Levels of serum PTH, glucose, K and Na were significantly related to occurrence of hypocalcaemia with p values: 0.006, 0.001, 0.019 and 0.001, respectively. Impact of diet, housing criteria and periodical health monitoring by metabolic profile test were found to affect significantly on incidence of hypocalcaemia on farm level with p value ≤ 0.008 for all. On cow level, age of cows, parity, body condition score, stage of transition period, daily milk yield and previous transition period disorders were found to have a significant effect on occurrence of hypocalcaemia at p value ≤ 0.001 for each item. Conclusion and clinical relevance: Results of the current study point toward the importance of usual monitoring of transition period disorders in dairy cows, besides identifying potential risks and consequences of hypocalcaemia in an attempt to construct control measures for them, that in-turn would increase dairy herd profitability.

The aim of the current study focused on screening the signal of the vitamin D receptor (VDR), 1-alpha-hydroxylase (1α-OHase) enzyme, and chemokine regulated on activation, normal T-cell expressed and secreted (RANTES) genes in dairy cows with hypocalcaemia. A sample of 120 dairy cows (20 dairy cows per herd) in the transition period was studied. Blood samples were drawn from the selected dairy cows for both biochemical and molecular analysis. In cows with subclinical and clinical hypocalcemia, there was a significant (P<0.05) down-regulation of both VDR and RANTES genes, whereas there was a significant (P<0.05) up-regulation of the 1α-OHase enzyme. Moreover, there was a significant (P<0.05) increase in the levels of glucose, parathyroid hormone (PTH), sodium (Na), and chloride (Cl). Furthermore, there was a significant (P<0.05) decrease in the levels of phosphorous and potassium (K). On the animal level, there was a significant association between the expression pattern of the VDR gene and the cows’ breed, the cows’ age, parity number, body condition score, and history of previous transition period disorders. The increase in both the expression of 1α-OHase enzyme and the level of each of PTH, glucose, Na, and Cl in the serum were significant risk factors for the decreased expression of the VDR gene. Likewise, the decrease in both the expression of the RANTES gene and the level of calcium (Ca) and phosphorous in the serum were significant risk factors for decreased expression of the VDR gene. This study revealed that the expression of VDR, 1α-OHase enzyme, and RANTES genes in the blood was greatly affected in dairy cows with hypocalcemia, indicating the need for an extra dose of vitamin D to maintain the normal level of Ca in the blood, especially during periods of high need. Hence, this study provides an insight into the role of vitamin D and its related enzymes in promoting the productivity of dairy cows, especially during the critical production periods.

To identify the most prevalent diseases of transition period in dairy cows and to highlight potential risk factors that are supposed to play a critical role in the prevalence of hypocalcaemia. Design: Case-control study Animals: 179 transition dairy cows belonged to five farms. Procedures: In the selected dairy cows, both clinical examination and serum analysis were used as a key to diagnose the transition period disorders. The serum analytes were measured, including calcium (Ca), inorganic phosphorous (P), magnesium (Mg), parathyroid hormone (PTH), glucose, potassium (K), sodium (Na) and chloride (Cl) and then their cutoff points were set. A questionnaire was constructed to identify the possible risk factors associated with hypocalcaemia on both the farm and cow level. Results: In this study, the prevalence of hypocalcaemia, hypophosphatemia, hypomagnesaemia, hypoglycemia, hypokalemia, clinical ketosis, and abomasal displacement was 48.04%, 40.22%, 33.52%, 29.05%, 58.1%, 5.59%, and 1.12%, respectively. Furthermore, the prevalence of post parturient septic metritis, retained placenta, and clinical mastitis was 26.81%, 23.46%, 18.99%, respectively. On farm level, the type of the diet, housing criteria, and periodical monitoring of metabolic profile test significantly (P < 0.05) affected the incidence of hypocalcaemia. On cow level, age, parity, body condition score, stage of transition period, daily milk yield, and history of presence of previous transition period disorders had a significant (P < 0.05) effect on the occurrence of hypocalcaemia. Moreover, the occurrence of hypocalcaemia in the studied dairy cows was significantly correlated with high level of each of PTH (P = 0.006), glucose (P = 0.001), K (P = 0.019), Na (P = 0.001), and Cl (P = 0.045). Conclusion and clinical relevance:The results of the current study pointed the importance of regular monitoring of the transition period disorders in dairy cows, besides the identification of the potential risks and consequences of hypocalcaemia in an attempt to establish control measures for them, which in turn will increase the profitability of dairy herds.

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