Abstract:
The early lactation period of dairy cows in Sri Lanka has been identified with negative
energy balance (NEB) due to improper feeding strategies. Hence, the objective of the current
study was to evaluate the energy balance of temperate crossbred dairy cows in early
lactation reared under two management systems (stallfed and tethered) at Welimada
Veterinary Division. Forty dairy cows in early lactation were selected for the study (stallfed,
n=20, and tethered, n=20). The energy balance was evaluated using a serum metabolic
profile. Blood samples collected (between 0900 to 1030 hrs.) from each cow were analysed
for serum Non-esterified fatty acids (NEFA) and Beta-hydroxybutyrate (BHBA) contents
and values were compared with reference ranges. Milk production, parity, days in milk
(DIM), and amount of concentrate fed were recorded. The average DIM was recorded as
30.75 days. The NEFA content of cows in both systems (0.30±0.05 vs. 0.39±0.07 mmol L-1
)
was below the upper critical limit of the reference range and no significant difference
(p>0.05) was observed between systems. Yet, the BHBA content of cows in the tethered
system was significantly higher (p<0.05) than its counterpart (0.81±0.22 vs. 0.35±0.06
mmol L-1
) and it was close to the upper critical limit (0.854 mmol L-1
). Higher BHBA
contents indicate NEB conditions during early lactation. The number of concentrates fed to
stall-fed cows was observed to be significantly higher (p<0.05) than its counterpart
(13.64±0.42 vs. 4.46±0.29 kg/cow/d). Similarly, stallfed cows indicated higher (p<0.05)
milk production (19.88±0.26 vs. 6.93±0.40 L/cow/d). Results revealed that only the tethered
cows were affected with NEB status. The reasons for low milk production and NEB in
tethered cows could be due to lack of energy intake which was indicated by the low amount
of concentrate fed. Further research is warranted to identify methods for increasing the
energy intake of tethered dairy cows at early lactation while considering the socioeconomics
of the farming system.
Keywords: Beta-hydroxybutyrate, Milk production, Non-esterified fatty acids, Stallfed,
tethered
