Google+ Effects of Heat Stress on Milk Production in Cattle


Effects of Heat Stress on Milk Production in Cattle

by Yadav Sharma Bajagai

Reduction in milk production is one of the major economic impacts of climatic stress in dairy cattle. Decrease in milk yield due to heat stress is more prominent in Holstein than in Jersey cattle [1]. Decreased synthesis of hepatic glucose and lower non esterified fatty acid (NEFA) level in blood during heat stress [2, 3, 4] causes reduced glucose supply to the mammary glands resulting low lactose synthesis which in turn ensues low milk yield [5]. Reduction in milk yield is further intensified by decrease in feed consumption by the animals to compensate high environmental temperature [5, 6].

Reduced milk production due to heat stress is attributable only partly to decrease in feed intake [7]. Actually 35% of reduced milk production is due to decreased feed intake while remaining 65% is attributable to direct effect of heat stress [7]. Other factors resulting reduced milk production during heat stress are decreased nutrient absorption, effect in rumen function and hormonal status and increased maintenance requirement resulting reduced net energy supply for production [8, 9].

Milk production in cow has been found to be reduced when ambient temperature and temperature humidity index increases above critical threshold [10, 11]. Heat stress during 60 days prepartum period negatively affects postpartum milk production [12] and cows parturated during summer produce less milk as compared to other season [17]. Similarly, quantity of milk protein and solid not fat (SNF) have been found to be reduced during heat stress in dairy cattle [7, 13, 14]. Mallonee [15] reported 20% less milk yield in cattle kept in sun than milk yield in cattle kept in shed. Similarly, Roman-Ponce [16] found 10.7% higher milk production in cows kept in shed than that in cows kept in sun during hot weather.


  1. The Holstein and Jersey dairy breeds have emerged to be the top two breeds in the world and their popularity is primarily due to the two breeds having the ability to convert large quantities of forage-based diets into milk and milk components. As mentioned by Underwood JP ( Illini Dairy Net) made a comparison between these two major breeds for their performance in the USA.

    For the year 1999, registered Holsteins averaged on a 305-day M.E. basis, 24,291 pounds milk, 3.66 percent milk fat, 888 pounds milk fat, 3.15 percent milk protein, and 765 pounds milk protein.

    Registered Jerseys averaged 16,997 pounds milk, 4.57 percent milk fat, 776 pounds milk fat, 3.72 percent milk protein, and 633 pounds milk protein.

    Comparative features of the two Breeds (something that should be considered in formulating dairy policy with regards to breed selection and promotion in countries like Nepal):

    Holsteins are more profitable than Jerseys under fluid milk markets and in the sale of market cows and bull calves.

    Jerseys are competitive with Holsteins under component milk markets.

    Holsteins and Jerseys have similar feed efficiency.

    Jerseys are superior in reproductive efficiency.**

    **Reproduction Efficiency and performance under poor management should be given huge emphasis in conditions prone to climatic and other stresses.
    (Text available at :

    1. Thank you very much for sharing such an important information.

  2. i'd be grateful if you please tell me the detailed feeding chart for milking jersey cow in nepal..