Journal of Advances in Biology & Biotechnology

Reproductive disorders such as true anoestrus and silent oestrus are major causes of infertility and economic loss in dairy cattle, particularly under field conditions where nutritional and managemental factors greatly influence reproductive performance. The present study was conducted to study the prevalence of reproductive disorders in crossbred cows and to determine the incidence and biochemical alterations associated with true anoestrus and silent oestrus in crossbred cows maintained under field conditions in Assam. A total of 1374 crossbred cows from private farms in the greater Guwahati area were examined through breeding history, clinico-gynaecological, and ultrasonographic evaluations. For biochemical analysis of blood serum, Serum calcium, inorganic phosphorus, zinc, total protein, and cholesterol were estimated using an automatic biochemistry analyzer following the protocols provided with commercial kits. Out of 1374 crossbred cows, 1172 (85.3%) were found normal, while 102 (7.42%) and 100 (7.28%) were identified as repeat breeders and anoestrus cows, respectively. The overall incidence of silent oestrus and true anoestrus was 4.58% (63/1374) and 2.69% (37/1374), respectively. Biochemical analyses revealed significantly (p<0.05) lower serum calcium levels and higher cholesterol and total protein concentrations in true anoestrus cows compared to normal cyclic ones, while differences in phosphorus and zinc levels were non-significant. The findings indicate that nutritional and metabolic imbalances, particularly calcium deficiency and altered lipid and protein metabolism, play crucial roles in the occurrence of anoestrus. The study underscores the importance of mineral supplementation, balanced nutrition, and proper management to enhance reproductive efficiency and productivity in crossbred dairy herds under field conditions of Assam.