Navigation Links
Heat stress influences low conception of dairy herds
Date:9/6/2007

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 animals 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 23-27C.

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 27C, only maximum daily temperatures <20C led to a significant increase in fertility. It should be stressed that in our geographical area, the maximum temperature was only <20C 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.


'/>"/>

Contact: Irina Garcia-Ispierto
Irina.Garcia@uab.es
34-935-811-091
Universitat Autonoma de Barcelona
Source:Eurekalert

Related biology news :

1. A little stress gives beneficial oomph! to immune system
2. Immune systems distress signal tells bacteria when to strike back
3. Scientists discover the bodys marijuana-like compounds are crucial for stress-induced pain relief
4. Endocannabinoids ?the brains cannabis ?demonstrate novel modes of action to stress
5. Penguin chicks exposed to human visitors experience spike in stress hormone
6. Stressed cells spark DNA repair missteps and speed evolution
7. Research Permits First-Ever Visualization of Psychological Stress in the Human Brain
8. Stress substantially slows human bodys ability to heal
9. Researchers unravel DNA tangles and enzyme seamstresses
10. Key stress protein linked to toxicities responsible for Parkinsons, Alzheimers
11. Just like us, social stress prompts hamsters to overeat, gain weight
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/7/2017)...   MedNet Solutions , an innovative SaaS-based eClinical ... research, is pleased to announce that the latest release ... flexible and award winning eClinical solution, is now available ... is a proven Software-as-a-Service (SaaS) clinical research technology platform ... also delivers an entire suite of eClinical tools to ...
(Date:2/3/2017)... 3, 2017  Texas Biomedical Research Institute announced that its ... Schlesinger as the Institute,s new President and CEO. Dr. ... 31, 2017. He is currently the Chair of the Department ... for Microbial Interface Biology at Ohio State University. ... President and CEO of Texas Biomed," said Dr. James ...
(Date:2/2/2017)... Feb. 1, 2017  Central to its deep ... advances worldwide, The Japan Prize Foundation today announced ... have pushed the envelope in their respective fields ... Three scientists are being recognized with the 2017 ... not only contribute to the advancement of science ...
Breaking Biology News(10 mins):
(Date:2/22/2017)... , ... February 22, 2017 , ... ... is has acquired Kendall Research Systems, LLC (KRS) clinical development program. ... develops neural interface technology for research and clinical applications. The terms of the ...
(Date:2/22/2017)... 22, 2017  PrimeVax Immuno-Oncology, Inc. announced today its ... the Annual Biocom Global Life Science Partnering Conference.  The ... AM, at the Torrey Pines Lodge, in San Diego.  ... at Biocom who have chosen our company, amongst numerous ... companies, investors, and clinical researchers," said Mr. Chen. "In ...
(Date:2/22/2017)... (PRWEB) , ... February 22, ... ... Collaborative (TOPEC), the leading medical education provider of women’s health, primary ... by the Accreditation Council for Continuing Medical Education (ACCME). ACCME’s Accreditation with ...
(Date:2/22/2017)... ... February 22, 2017 , ... ... engineers, and scientists from around the world, is pleased to announce the 2nd ... and 23, 2017. This premier, online-only conference focused on the development and advancements ...
Breaking Biology Technology: