Featured Research

from universities, journals, and other organizations

Heat Stress Influences Low Conception Of Dairy Herds

Date:
September 7, 2007
Source:
Universitat Autonoma de Barcelona
Summary:
Summer heat stress is a main factor related to low conception rates in high producing dairy herds in warm areas worldwide. A research group studied the impact of several climate variables on conception rates in high producing dairy cows in northeastern Spain by examining 10,964 inseminations.

Reproductive efficiency has suffered a dramatic decrease since the mid 1980s despite rapid worldwide progress in genetics and management of high producing dairy herds. The reasons for the decline in fertility are multifactorial and cannot be solely attributed to an increase in milk production. We propose that summer heat stress is likely to be a major factor related to low fertility in high producing dairy herds, especially in countries with warm weather.

The environmental temperature, radiant energy, relative humidity, and wind speed all contribute to the degree of heat stress. Heat stress may be defined as any combination of environmental variables that give rise to conditions that are higher than those of the temperature range of the animal's thermal neutral zone. The temperature-humidity index (THI) incorporates the effects of both ambient temperature and relative humidity (RH) in an index. This index is widely used in hot areas worldwide to assess the impact of heat stress on humans and dairy cows.

We analyzed data derived from 10,964 inseminations in 4 herds during 3 years. Climate data such as daily mean and maximum temperature mean and minimum relative humidity, and rainfall were obtained from a meteorological station located less than 6 km away within the herds. Mean and maximum THI were calculated during 7 days before insemination to 3 days postinsemination. Fans are activated when temperature arise at 23-27ēC.

Results indicated that high THI during 3 days before insemination, specially the Day 3 before, reduced fertility, probably due to ovulation failure. Ovulation failure was 3.9 times higher in cows inseminated during the warm period (May-September) compared to the cool period (October-April). THI on the day of insemination is also important for fertility, probably because heat stress could affect oocytes, spermatozoa and embryos.

A high maximum temperature on day 1 after insemination was found to reduce conception rate. Although it has been described that hyperthermia in lactating dairy cows can occur at air temperatures as low as 27°C, only maximum daily temperatures <20ēC led to a significant increase in fertility. It should be stressed that in our geographical area, the maximum temperature was only <20ēC for 170 days per year.

As an overall conclusion, climate factors seem to be highly relevant for conception rate. The use of maximum temperatures gives more information that the one provided by THI variables. Thus, the use of the THI or temperature to control a farm environment would depend on the individual farm and on each environmental situation, but it is important to check temperature and humidity to know when to adopt cooling measures. Further studies should try to establish the effect of global warming at the farm level. This problem is reflected with warm summers and even with peaks of temperatures in winter.


Story Source:

The above story is based on materials provided by Universitat Autonoma de Barcelona. Note: Materials may be edited for content and length.


Cite This Page:

Universitat Autonoma de Barcelona. "Heat Stress Influences Low Conception Of Dairy Herds." ScienceDaily. ScienceDaily, 7 September 2007. <www.sciencedaily.com/releases/2007/09/070906104132.htm>.
Universitat Autonoma de Barcelona. (2007, September 7). Heat Stress Influences Low Conception Of Dairy Herds. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2007/09/070906104132.htm
Universitat Autonoma de Barcelona. "Heat Stress Influences Low Conception Of Dairy Herds." ScienceDaily. www.sciencedaily.com/releases/2007/09/070906104132.htm (accessed July 23, 2014).

Share This




More Earth & Climate News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Observation Boat to Protect Cetaceans During Ship Transfer

Observation Boat to Protect Cetaceans During Ship Transfer

AFP (July 22, 2014) — As part of the 14-ship convoy that will accompany the Costa Concordia from the port of Giglio to the port of Genoa, there will be a boat carrying experts to look out for dolphins and whales from crossing the path of the Concordia. Duration: 01:02 Video provided by AFP
Powered by NewsLook.com
New Orleans Plans to Recycle Cigarette Butts

New Orleans Plans to Recycle Cigarette Butts

AP (July 21, 2014) — New Orleans is the first U.S. city to participate in a large-scale recycling effort for cigarette butts. The city is rolling out dozens of containers for smokers to use when they discard their butts. (July 21) Video provided by AP
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) — A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 21) Video provided by AP
Powered by NewsLook.com
Spectacular Lightning Storm Hits London

Spectacular Lightning Storm Hits London

AFP (July 19, 2014) — A spectaCular lightning storm struck the UK overnight Friday. Images of lightning strikes over the Shard and Tower Bridge in central London. Duration: 00:23 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins