257 Pakistan Veterinary Journal ISSN: 0253-8318 (PRINT), 2074-7764 (ONLINE) DOI: 10.29261/pakvetj/2019.122 Postpartum Cyclicity of Holstein-Friesian Crossbred Cows Shows Relation with Serum Biochemical Profiles during 45-60 Days Postpartum AHM Musleh Uddin 1* , M Atikuzzaman 1 , Md Siddiqul Islam 2 and M Kawser Hossain 1 1 Department of Surgery and Theriogenology; 2 Department of Pharmacology and Toxicology, Faculty of Veterinary, Animal and Biomedical Sciences, Sylhet Agricultural University, Sylhet, Bangladesh *Corresponding author: musleh.dst@sau.ac.bd ARTICLE HISTORY (19-437) ABSTRACT Received: Revised: Accepted: Published online: September 23, 2019 November 20, 2019 November 22, 2019 December 06, 2019 Reproductive performance of dairy cows is greatly affected by energy, protein and mineral profiles, which is also connected to postpartum anestrus. The present study was conducted during the period from December 2018 to May 2019 on 30 local x Holstein-Friesian crossbred lactating cows with parity 1-5 and body condition score of 2.0-3.5. This study aimed to compare serum glucose, cholesterol, triglycerides, total proteins, urea nitrogen, calcium, phosphorus and magnesium concentrations between anestrus and normal cyclic crossbred cows during 45 to 60 days postpartum. Automated biochemical analyzer was employed to measure these concentrations, using 15 cows in each group. The serum of postpartum anestrus cows contained significantly lower (P<0.05) concentrations of glucose, total proteins, calcium and magnesium compared to normal cyclic cows, while urea nitrogen concentration was significantly increased (P<0.05) in the postpartum anestrus cows. However, concentrations of other serum biochemical metabolites did not differ between cows of the two groups. These results suggest that blood glucose, total proteins, calcium, magnesium and urea nitrogen might have an effect on the cyclicity of Holstein-Friesian crossbred cows during 45 to 60 days postpartum. However, further studies are recommended to explore the underlying mechanism for the role of these metabolites in the cyclicity of postpartum cows. ©2019 PVJ. All rights reserved Key words: Biochemical profile Crossbred cows Cyclicity Postpartum anestrus Voluntary waiting period To Cite This Article: Uddin AHMM, Atikuzzaman M, Islam MS and Hossain MK, 2020. Postpartum cyclicity of Holstein-Friesian crossbred cows shows relation with serum biochemical profiles during 45-60 days postpartum. Pak Vet J, 40(2): 257-260. http://dx.doi.org/10.29261/pakvetj/2019.122 INTRODUCTION A cow must be bred successfully within 80-85 days postpartum to achieve the desired calving interval of 365 days (Khan et al., 2010). First ovulation within 21 days in postpartum cows is associated with improved reproductive performance and subsequent normal estrous cycles (Cheong et al., 2016). However, the postpartum cows may go through a temporary infertility known as postpartum anestrus, which is commonly influenced by infectious and non-infectious reasons- such as uterine involution, hormonal and nutritional status of the cows (Peter et al., 2009).This problem in crossbred cows is an important barrier for sustainable dairy farming system that caused huge economic losses to the large and small scale dairy farms in Bangladesh (Pariza et al., 2013). Daily energy balance nadir is considered as major metabolic modulator of postpartum ovarian activity and plays a vital role in anestrus in dairy cows (Beam and Butler, 1999). Lactating cows for a four-month period of postpartum anestrus with inactive ovaries are reported having changes in blood energy metabolites such as reduced level of glucose and increased level of total cholesterol (CHOL-T). Serum total proteins (PRO-T) and blood urea nitrogen (BUN) are responsible for desirable reproductive performance in cows (Puppel and Kuczyriska, 2016). Postpartum anestrus has also been found to be associated with deficiencies of calcium (Kumar et al., 2010), phosphorus (Das et al., 2012) and magnesium (Dutta et al., 2001). However, all these studies have covered a long postpartum period and are unable to visualize the relation of blood biochemical properties with anestrus after uterine involution is completed and before the end of the voluntary waiting period (VWP), that is day 45-60 postpartum. It is recommended that a minimal VWP of 45 to 60 days postpartum is required, allowing for a complete uterine involution and normal ovarian cyclicity of cows to RESEARCH ARTICLE