Effects of Total Mixed Ration on Blood Biochemistry, Productivity, and Reproduction in Bangladeshi Frisian Crossbred Lactating Cows

Background This study assessed the impact of the total mixed ratio (TMR) on milking cow productivity and reproductive and serum biochemical profiles and investigated the correlations between TMR nutrient values and cow traits. Results A total of 95 lactating cows were used and grouped into TMR1, TMR2 and TMR3 according to the TMR provided. The study revealed that all three meals had 96.3% dry matter, with TMR3 having the most nitrogen-free extract, crude fiber, and crude protein, whereas TMR-1 had the least protein, crude fiber, and neutral detergent fiber. Considering the nutritive values of the TMR provided to the lactating cows, crude fiber (CF), crude protein (CP), N-free extract, acid detergent fiber (ADF), and neutral detergent fiber (NDF) percentages significantly (p < 0.05) differed among the TMR subgroups. The study revealed no significant outliers in body weight, daily milk yield, lactation length, first day of peak yield, or duration of peak yield in cows in the TMR3 group. The cows in the TMR 1 group presented the greatest first-day pick yield after calving, daily milk output, lactation length, and pick yield duration. Daily milk output and lactation duration were moderately to strongly positively correlated with CP and CF. Reproductive indicators varied more than productive features did in Group TMR3 cows. However, the medians for age at first artificial insemination (AI), calving to first heat, first AI, and the calving interval were comparable across all groups. Energy- and protein-rich meals improved reproductive efficiency, whereas fat content had no effect. The research revealed that TMR2 cows had considerably lower magnesium levels than TMR1 and TMR3 cows did. AST levels were higher in TMR2 and TMR3 cows than in TMR1 cows, whereas ALP levels were lower in TMR2 cows. Body weight had a significant (p < 0.01) positive relationship with crude fiber% and NDF%, a negative relationship with crude protein%, nitrogen-free extract, and ADF% milk yield, a strong (p < 0.01) negative relationship with DM%, Ash%, crude fiber%, fat%, and NDF%, and a positive relationship with CP%, N-free extract%, and ADF. The results revealed a significant negative relationship between the duration of pick yield and N-free extract%, ADF%, triglyceride, alkaline phosphatase (ALP), and glucose contents and a positive relationship with crude protein% and NDF%. Calving to the first heat was significantly (p < 0.01) negatively related to TP and ALP and positively related to lactation duration (p < 0.01). Conclusion This study suggests that efficient ration formulation can enhance milk production, reproductive performance, and metabolic health in dairy herds of Frisian crossbred lactating cows in Bangladesh.