Evaluation of Energy Balance in Tropical and Temperate Crossbred Dairy Cows at Post-Partum Transition Stage: A Case Study

Objective of the present study was to assess the energy balance of tropical (Sahiwal x Jersey) and temperate (Friesian x Jersey) crossbred dairy cows in Sri Lanka using serum metabolic profile.  The study consisted of tropical and temperate crossbred dairy cows which were at post-partum transition stage, and were from two medium-scale farms in low country dry zone, and mid country intermediate zone, respectively.  Each cow was bled (0800 hours) on the day of data collection and serum metabolic profile was assessed. Milk production, body weight and body condition score (BCS) of cows were recorded whereas, dry matter, crude protein and metabolizable energy contents of the mixed rations fed to cows in both farms were analysed.  Results revealed that, serum non-esterified fatty acids (NEFA), urea and calcium contents were significantly (P<0.05) high, serum betahydroxybutyric acid (BHBA) content was significantly (P<0.05) low in temperate crossbred cows compared to those of tropical crossbred cows at post-partum transition stage. The serum BHBA content (1.32±0.11 mmol/L) of tropical crossbred cows, and NEFA (0.62±0.15 mmol/L) and urea (30.09±2.60 mg/dL) content of temperate crossbred cows at post-partum transition stage exceeded the upper critical limit of the reference range proposed for the determination of NEB. The recorded inferior BCS of both tropical (2.9±0.6) and temperate (2.5±0.2) crossbred dairy cows further confirmed their poor energy balance under the present feeding system. It was concluded that, both tropical and temperate crossbred dairy cows at post-partum transition stage suffer from negative energy balance under the current feeding system in the two medium-scale farms studied.  The BHBA level was suggested as more appropriate indicator to assess the energy balance in dairy cows, managed under free-stall system.  Adoption of energy-dense feeding programs and overcoming energy deficiency are suggested to optimize the productivity of dairy cattle in low-country, dry-zone and mid-country intermediate-zone.