DNA helix intertwined with sheep, representing genetic improvement in livestock.

Unlocking Genetic Potential: How Understanding Sheep Heritability Can Improve Your Flock

Lena Voss in Science & Nature June 2025 • 4 min read.

"Dive into the groundbreaking research on Barki lambs and discover how genetic insights can revolutionize breeding for growth and resilience."

For centuries, breeders have relied on intuition and observation to improve livestock. But what if you could unlock the hidden potential within your flock by understanding the science of genetics? New research is shedding light on the heritability of key growth traits in Barki lambs, offering valuable insights for more effective breeding strategies.

Genetic heritability, simply put, is the extent to which a trait is passed down from parents to offspring. Understanding which traits are highly heritable—and which are more influenced by environmental factors—allows breeders to make targeted selection decisions. By focusing on the most heritable traits, you can accelerate genetic progress and achieve significant improvements in flock performance.

This article delves into a recent study that examined genetic parameters and variance components of pre-weaning growth traits in Barki lambs. Barki sheep, native to Egypt, are known for their adaptability to harsh desert environments, making them a valuable breed for arid regions. By understanding the genetic underpinnings of growth in these lambs, breeders can optimize breeding programs not only for Barki sheep but also potentially for other breeds facing similar environmental challenges.

Decoding the Genetic Blueprint: What the Research Reveals

DNA helix intertwined with sheep, representing genetic improvement in livestock.

Researchers Ahmed M. Sallam, Adel H. Ibrahim, and Samir M. Alsheikh conducted a comprehensive study, analyzing data from over 5,000 Barki lambs born between 1972 and 2016. Their goal was to estimate the heritability of key growth traits, including birth weight (BW), weaning weight (WW), and pre-weaning average daily gain (ADG). By using restricted maximum likelihood (REML) techniques, the researchers were able to tease apart the genetic and environmental influences on these traits.

One of the key findings was that the heritability of pre-weaning weights in Barki sheep was lower than expected. While moderate heritability was observed, several factors greatly influenced weight gain.

Birth Weight (BW): Direct heritability was estimated at 0.07, indicating that only a small portion of the variation in birth weight is due to direct genetic factors. Maternal effects, however, played a significant role, accounting for approximately 15% of the variation.
Weaning Weight (WW): Direct heritability was higher at 0.15, suggesting a greater influence of the lamb's own genes on weaning weight. Maternal effects were less pronounced, accounting for about 6% of the variation.
Average Daily Gain (ADG): Similar to weaning weight, average daily gain showed a direct heritability of 0.16, with maternal effects contributing around 10% of the variation.

These results highlight the complex interplay between genetics and environment in determining growth traits. While genetics provide the foundation, maternal factors—such as milk production and mothering ability—can significantly impact a lamb's early development.

Practical Implications: Breeding Strategies for the Modern Shepherd

So, what does this research mean for you, the shepherd? Understanding the heritability of growth traits allows you to fine-tune your breeding strategies for optimal results. Here are a few key takeaways:Focus on Direct Genetic Selection: For weaning weight and average daily gain, direct genetic selection—choosing rams and ewes with superior performance for these traits—can lead to meaningful improvements in your flock.Consider Maternal Effects: Don't underestimate the importance of maternal traits, especially for birth weight. Select ewes with a proven track record of good mothering ability and adequate milk production.Optimize the Environment: Since environmental factors play a significant role in early growth, ensure your lambs have access to high-quality nutrition, proper health care, and a stress-free environment.Monitor Genetic Trends: Regularly evaluate the genetic and phenotypic trends in your flock to track progress and identify areas for improvement. This may involve keeping detailed records of lamb performance and using genetic evaluation tools.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.smallrumres.2018.11.027, Alternate LINK

Title: Estimation Of Genetic Parameters And Variance Components Of Pre-Weaning Growth Traits In Barki Lambs

Subject: Animal Science and Zoology

Journal: Small Ruminant Research

Publisher: Elsevier BV

Authors: Ahmed M. Sallam, Adel H. Ibrahim, Samir M. Alsheikh

Published: 2019-04-01

Everything You Need To Know

What exactly is genetic heritability, and why is it important in the context of sheep breeding, specifically with Barki lambs?

Genetic heritability is the degree to which a specific trait is passed from parents to their offspring. In the context of Barki lambs, this involves the transfer of traits such as birth weight (BW), weaning weight (WW), and pre-weaning average daily gain (ADG). The understanding of heritability allows breeders to predict how well a trait will respond to selective breeding. By focusing on highly heritable traits, breeders can make informed choices about which animals to breed, leading to improvements in the flock's overall performance and productivity. The study on Barki lambs suggests that while direct heritability for certain traits is moderate, maternal effects also play a significant role.

What were the key findings of the research on Barki lambs, and how can they be applied in practical sheep farming?

The study on Barki lambs provides valuable insights for modern sheep breeders. Researchers Ahmed M. Sallam, Adel H. Ibrahim, and Samir M. Alsheikh found that the direct heritability of birth weight (BW) in Barki lambs was 0.07, weaning weight (WW) was 0.15, and pre-weaning average daily gain (ADG) was 0.16. These figures suggest that while genetics play a role, environmental factors, particularly maternal effects, also significantly influence growth traits. This information helps breeders to fine-tune their breeding programs and make effective breeding decisions. For example, the study on Barki lambs highlights the importance of choosing ewes with good mothering ability and ensuring lambs have access to high-quality nutrition.

How does understanding heritability influence the breeding strategies that are used to improve a flock?

Understanding heritability impacts breeding strategies significantly. Because pre-weaning weights in Barki sheep showed moderate heritability, breeders can make targeted selection decisions. For traits like weaning weight (WW) and pre-weaning average daily gain (ADG), selecting rams and ewes with superior performance can improve the flock. Since environmental factors and maternal effects also contribute, breeders are advised to optimize the environment by ensuring high-quality nutrition, proper health care, and a stress-free environment. Monitoring genetic trends and keeping records of lamb performance is crucial. This holistic approach, considering both genetics and environment, allows breeders to achieve optimal results.

What are maternal effects, and how do they affect the growth and development of Barki lambs?

Maternal effects refer to the influence a ewe's characteristics have on her offspring, particularly in early development stages. In the context of the Barki lambs study, maternal effects were observed to significantly impact birth weight (BW). While the direct heritability of BW was low, maternal effects accounted for approximately 15% of the variation. Maternal effects include factors such as the ewe's milk production and mothering ability. These factors influence the lamb's early growth and survival, which is why selecting ewes with a good track record of these traits is critical. Breeders need to consider maternal effects along with direct genetic selection to maximize the potential of their flock.

What is the significance of the study's findings on Barki lambs, and how can it be used to enhance sheep breeding practices?

The key findings from the study on Barki lambs highlight the importance of both genetics and environment in determining growth traits. The study found that direct heritability for pre-weaning growth traits was moderate. However, maternal effects significantly influenced these traits. For example, direct heritability of weaning weight (WW) was 0.15, while maternal effects contributed to the overall variation. These results guide breeding strategies by emphasizing the need to consider both direct genetic selection and the impact of the environment, including maternal traits. By focusing on these factors, breeders can improve flock productivity, resilience, and overall profitability. The study's implications extend to other breeds facing similar environmental challenges, thus providing a broader application of the findings.