| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
* Animal & Dairy Science Department and
Statistical and Computer Services University of Georgia Coastal Plain Experiment Station Tifton 31793-0748
Corresponding author:
J. W. West; e-mail:
jwest{at}tifton.uga.edu.
Lactating cows were exposed to moderate and hot, humid weather to determine the effect of increasing ambient temperature, relative humidity, or temperature-humidity index (THI) on intake, milk yield, and milk temperature. Minimum and maximum temperatures averaged 17.9 and 29.5°C (cool period) and 22.5 and 34.4°C (hot period), and minimum and maximum THI averaged 63.8 and 76.6 (cool period) and 72.1 and 83.6 (hot period). Environmental conditions had minor effects on intake and milk yield during the cool period. During the hot period, the THI 2 d earlier and mean air temperature 2 d earlier had the greatest impact on milk yield and DMI, respectively. Both breeds maintained milk temperature within normal ranges during the cool period, but Holstein and Jersey p.m. milk temperatures averaged 39.6 and 39.2°C during the hot period. Current day mean air temperature during the hot period had the greatest impact on cow p.m. milk temperature, and minimum air temperature had the greatest influence on a.m. milk temperature. Dry matter intake and milk yield declined linearly with respective increases in air temperature or THI during the hot period and milk temperature increased linearly with increasing air temperature. Dry matter intake and milk yield both exhibited a curvilinear relationship with milk temperature. Environmental modifications should target the effects of high temperatures on cow body temperature and should modify the environment at critical times during the day when cows are stressed, including morning hours when ambient temperatures are typically cooler and cows are not assumed to be stressed.
Key Words: lactation • intake • heat stress • milk temperature
Abbreviation key: COOL = cool period, HOT = hot period, RH = relative humidity, THI = temperature-humidity index
This article has been cited by other articles:
|
|
 |
|
  M. I. Endres and A. E. Barberg Behavior of Dairy Cows in an Alternative Bedded-Pack Housing System J Dairy Sci, September 1, 2007; 90(9): 4192 - 4200. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. B. Cook, R. L. Mentink, T. B. Bennett, and K. Burgi The Effect of Heat Stress and Lameness on Time Budgets of Lactating Dairy Cows J Dairy Sci, April 1, 2007; 90(4): 1674 - 1682. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. D. Wildman, J. W. West, and J. K. Bernard Effect of Dietary Cation-Anion Difference and Dietary Crude Protein on Performance of Lactating Dairy Cows During Hot Weather J Dairy Sci, April 1, 2007; 90(4): 1842 - 1850. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. De Palo, A. Tateo, F. Zezza, M. Corrente, and P. Centoducati Influence of Free-Stall Flooring on Comfort and Hygiene of Dairy Cows During Warm Climatic Conditions J Dairy Sci, December 1, 2006; 89(12): 4583 - 4595. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. E. Cabrera, A. de Vries, and P. E. Hildebrand Prediction of Nitrogen Excretion in Dairy Farms Located in North Florida: A Comparison of Three Models J Dairy Sci, May 1, 2006; 89(5): 1830 - 1841. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. W. West Effects of Heat-Stress on Production in Dairy Cattle J Dairy Sci, June 1, 2003; 86(6): 2131 - 2144. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
