Related Experiment Video
Updated: Jul 19, 2026
14:40
Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings
Published on: October 25, 2015
Environmental effects on pregnancy rate in beef cattle.
J L Amundson1, T L Mader, R J Rasby
1Department of Animal Science, University of Nebraska, Lincoln, NE 68583-0908, USA.
Journal of Animal Science
|November 10, 2006
Summary
Environmental conditions significantly impact cattle breeding success. High temperatures and humidity reduce pregnancy rates in Bos taurus cows, especially early in the breeding season. Managing heat stress is crucial for optimizing fertility.
Area of Science:
- Reproductive physiology and environmental science in livestock management.
Background:
- Environmental factors, particularly heat stress, are known to affect cattle reproduction.
- Quantifying the impact of specific weather variables on pregnancy rates is essential for dairy and beef industries.
Purpose of the Study:
- To assess the influence of environmental conditions during the breeding season on pregnancy rates in Bos taurus crossbred cows.
- To identify critical temperature and humidity thresholds affecting reproductive success.
Main Methods:
- Analysis of ten years of calving records from Bos taurus crossbred cows.
- Calculation of estimated breeding dates and determination of breeding periods (0-21, 0-42, 0-60 days).
- Correlation of breeding success with daily weather data, including minimum temperature (MNTP), average temperature, relative humidity, and temperature-humidity index (THI).
Main Results:
- Minimum temperature (MNTP) and THI during the first 21 and 42 days of the breeding season were negatively associated with pregnancy rate (P < 0.001).
- The most significant negative impacts of temperature and THI on pregnancy rate occurred within the first 21 days.
- Optimal MNTP ranged from 12.6°C to 14.9°C, and optimal THI was 68.0, with reductions in pregnancy rate likely above 16.7°C MNTP and 72.9 THI.
Conclusions:
- Environmental conditions, especially heat stress, significantly reduce pregnancy rates in pasture-bred Bos taurus cows.
- Management strategies to mitigate heat stress during the early breeding season are vital for improving reproductive efficiency.
- Identifying optimal temperature and THI ranges can guide breeding season management to maximize conception rates.
Related Concept Videos
02:27Background and Environment Affect Phenotype
Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
01:11Testing a Claim about Mean: Known Population SD
A complete procedure of testing the hypothesis about a population mean is explained here.
Estimating a population mean requires the samples to be distributed normally. The data should be collected from the randomly selected samples having no sampling bias. The sample size needed to be higher than 30, and most importantly, the population standard deviation should be already known.
In most realistic situations, the population standard deviation is often unknown, but in rare circumstances, when it...
Estimating a population mean requires the samples to be distributed normally. The data should be collected from the randomly selected samples having no sampling bias. The sample size needed to be higher than 30, and most importantly, the population standard deviation should be already known.
In most realistic situations, the population standard deviation is often unknown, but in rare circumstances, when it...
01:07Teratogenicity
The ability of a drug to produce structural deformations and functional abnormalities in the developing embryo or the fetus is called teratogenicity, and the drug producing this effect is known as a teratogen. Teratogenic effects include stillbirth, miscarriage, intrauterine growth restriction, and neurocognitive delay. A teratogen may affect the embryo at different stages of development, which is important in determining the type and extent of the damage. During blastocyst formation, the early...
01:41Spermatogenesis
Spermatogenesis is the process by which haploid sperm cells are produced in the male testes. It starts with stem cells located close to the outer rim of seminiferous tubules. These spermatogonial stem cells divide asymmetrically to give rise to additional stem cells (meaning that these structures “self-renew”), as well as sperm progenitors, called spermatocytes. Importantly, this method of asymmetric mitotic division maintains a population of spermatogonial stem cells in the male reproductive...