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.

Related Articles


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 December 22, 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 December 22, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Lava Inches Closer to Highway

Raw: Lava Inches Closer to Highway

AP (Dec. 21, 2014) — Officials have opened a new road on Hawaii's Big Island for drivers to take care of their daily needs if encroaching lava from Kilauea Volcano crosses a highway and cuts them off from the rest of the island. (Dec. 20) Video provided by AP
Powered by NewsLook.com
Raw: Scuba Diving Santa Off Florida Keys

Raw: Scuba Diving Santa Off Florida Keys

AP (Dec. 20, 2014) — A scuba diving Santa Claus explored the waters of the Florida Keys National Marine Sanctuary. Dive shop owner Spencer Slate makes the dive each year to help raise money for charity. (Dec. 20) Video provided by AP
Powered by NewsLook.com
Obama: Better Ways to Create Jobs Than Keystone Pipeline

Obama: Better Ways to Create Jobs Than Keystone Pipeline

AFP (Dec. 19, 2014) — US President Barack Obama says that construction of the Keystone pipeline would have 'very little impact' on US gas prices and believes there are 'more direct ways' to create construction jobs. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com
Raw: Lava on Track to Hit Hawaii Market

Raw: Lava on Track to Hit Hawaii Market

AP (Dec. 19, 2014) — Lava from an active volcano on Hawaii's Big Island slowed slightly but stayed on track to hit a shopping center in the small town of Pahoa. (Dec. 19) Video provided by AP
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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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