~ 1508 ~ Journal of Entomology and Zoology Studies 2020; 8(4): 1508-1511 E-ISSN: 2320-7078 P-ISSN: 2349-6800 www.entomoljournal.com JEZS 2020; 8(4): 1508-1511 © 2020 JEZS Received: 10-05-2020 Accepted: 12-06-2020 D Bharali Scientist, Livestock Research Station, Assam Agricultural University, Hekra, Mondira, Kamrup, Assam, India KC Deka Professor (Retired), Department of Animal Reproduction, Gynaecology and Obstetrics College of Veterinary Science, Assam Agricultural University, Khanapara, Assam, India BC Deka Professor and Head (Retired) Department of Animal Reproduction, Gynaecology and Obstetrics, College of Veterinary Science, Assam Agricultural University, Khanapara, Assam, India KC Nath Professor (Retired), Department of Animal Reproduction, Gynaecology and Obstetrics, College of Veterinary Science, Assam Agricultural University, Khanapara, Assam, India RK Biswas Professor (Retired), Department of Animal Reproduction, Gynaecology and Obstetrics, College of Veterinary Science, Assam Agricultural University, Khanapara, Assam, India LJ Dutta Assistant Professor Department of Animal Reproduction, Gynaecology and Obstetrics, College of Veterinary Science, Assam Agricultural University, Khanapara, Assam, India BK Sarmah Joint Registrar, Assam Agricultural University, Khanapara, Assam, India B N Saikia Dean, College of Veterinary Science, Assam Agricultural University, Khanapara, Assam, India Corresponding Author: D Bharali Scientist, Livestock Research Station, Assam Agricultural University, Hekra, Mondira, Kamrup, Assam, India A comparative study on some biological constituents in serum during normal and silent estrous cycles of crossbred cows of Assam D Bharali, KC Deka, BC Deka, KC Nath, RK Biswas, LJ Dutta, BK Sarmah and BN Saikia Abstract For the present study a total of twenty normal cyclic and twenty confirmed silent estrous cows yielding 8 – 20 liters of milk were selected at random. Blood samples were collected from each animal on day 0, 10, 17 and 20 (day 0 of the next cycle) and each sample was analyzed for estimation of calcium, inorganic phosphorus, magnesium, zinc, total protein, glucose and cholesterol by using quality kits. The analysis of variance revealed that mean level of serum calcium, zinc, total protein, and glucose differ highly significant (p< 0.01) between different days of estrous cycle in both silent and normal estrous cows. While serum inorganic phosphorus and cholesterol did not differ significantly while serum magnesium differed significantly (p< 0.05) between different days but all above differed highly significant (p< 0.01) among different days of estrous cycle in silent and normal estrus cows. Keywords: Calcium, cholesterol, inorganic phosphorus, magnesium, silent estrus, zinc Introduction Silent estrus condition is one of the major reproductive problems of high yielding crossbred cows which contributing great economic loss to the dairy farmers. High yielding traits of crossbred cattle might be one of the stress factors leading to this problem [31] . High producing dairy cows have inherently low expression of estrus signs [25] , particularly during the early postpartum period. Cows affected with silent estrus are needed to be examined at frequent intervals for detection of estrus which is painstaking and tedious. Farmers cannot detect animals in silent estrus. Thus lack of behavioural signs of estrus, and or unobserved estrus or poor estrus detection efficiency of farmers in this condition can greatly increase the incidence of anestrus. Comparative information on serum biological constituents during the period of normal and silent estrous cycles of crossbred cattle under the prevailing condition of Assam appeared to be limited. Therefore, the present study was carried out to compare levels of different biological constituents in serum at different days of normal and silent estrous cycles of crossbred cows of Assam. Materials and methods A total of twenty normal cyclic and twenty silent estrous cows were selected at random for this study. Jugular blood samples were collected from each experimental animal on day 0, 10, 17 and 20 (day 0 of the next cycle) and each sample was used for estimation of calcium, inorganic phosphorous, magnesium, zinc other biological constituents like total protein, glucose, cholesterol by using quality kits. Then the values were statistically analyzed to compare the results between two groups and between different days of estrous cycle using standard software version (SPSS20). Results and Discussion The mean level of serum calcium, inorganic phosphorus, magnesium, zinc, total protein, glucose and cholesterol on different days of estrous cycle in silent and normal estrous cows has been presented in Table 1. The mean concentration of calcium in serum was ranged from 8.67 to 9.69 in silent estrous and 8.95 to 10.46 mg / dl in normal estrous cows. Significantly higher (P < 0.01) level of calcium was recorded on the day of estrus in both silent and normal estrous cows than on day