Table 4.
Dry matter intake, milk production, energy balance, plasma concentrations of metabolic and stress indicators, rectal temperature, resting time, respiration rate and rumination time in cooled vs. heat-stressed late-lactation cows.
| Cooled | Heat Stressed | SEM | p | |
|---|---|---|---|---|
| Dry matter intake, kg/d | 28.7 a | 24.8 b | 0.6 | 0.0005 |
| Milk production, kg/d | 32.3 a | 28.9 b | 0.9 | 0.02 |
| Fat corrected milk (4%), kg/d | 28.1 a | 24.0 b | 1.4 | 0.05 |
| Energy balance, Mcal/d | 15.2 a | 12.6 b | 0.9 | <0.0001 |
| BW gain, kg | 3.5 | 13.2 | 5.9 | 0.26 |
| NEFAs, µEq/L | 136.0 | 120.6 | 6.4 | 0.10 |
| Glucose, mg/dL | 62.8 | 59.3 | 1.8 | 0.19 |
| Cortisol, ng/mL | 1.09 | 1.03 | 0.04 | 0.35 |
| MDA, µM | 3.8 | 4.9 | 0.8 | 0.38 |
| TNF-α, pg/mL | 163.6 | 154.0 | 8.4 | 0.43 |
| Rectal temperature, morning | 37.8 b | 38.5 a | 0.08 | <0.0001 |
| Rectal temperature, afternoon | 38.4 b | 39.1 a | 0.08 | <0.0001 |
| Resting time, min/d | 586.7 | 543.2 | 18.7 | 0.11 |
| Respiration rate, morning | 28.6 b | 43.1 a | 3.2 | 0.005 |
| Respiration rate, afternoon | 48.6 | 58.6 | 3.8 | 0.08 |
| Rumination time, min/d | 517.5 | 512.9 | 9.8 | 0.7 |
NEFAs = Non-esterified fatty acids; MDA = Malondialdehyde; TNF-α = Tumor necrosis factor alpha; BW = Body weight. a,b Different letters within a row are significant at p < 0.05.