Nelore cattle under ultrasound with highlighted muscle growth and fat thickness.

Beefing Up Profits: How Smarter Cattle Selection Can Increase Muscle Mass

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

"Unlocking Genetic Secrets for Bigger, Leaner Nelore Cattle: A Data-Driven Approach to Maximizing Carcass Value Without Excess Fat"

For cattle ranchers, maximizing carcass value is a constant pursuit. Key to this goal is optimizing the longissimus muscle area (LMA), a prime indicator of muscling that translates directly to increased yield. Simultaneously, producers aim to manage subcutaneous fat thickness, which affects meat quality and consumer appeal. Striking the right balance between these traits is crucial for profitability.

Traditionally, carcass evaluation in Nelore cattle, a prominent breed in Brazil, has been conducted at 18 months of age. However, evaluating animals earlier, around 12 months, could accelerate genetic progress by allowing for earlier selection and breeding decisions. The challenge lies in understanding how growth traits correlate with carcass characteristics at different ages and whether selecting for increased growth inadvertently leads to excessive fat deposition.

This article explores recent research investigating the genetic relationships between growth traits and carcass traits in Nelore cattle, focusing on the potential for improving muscle mass without increasing subcutaneous fat. We will delve into how strategic selection based on easily measurable growth traits can lead to desirable carcass outcomes, ultimately helping producers make informed decisions to enhance the value of their herds.

Can You Really Have it All? Balancing Muscle and Fat in Cattle Breeding

Nelore cattle under ultrasound with highlighted muscle growth and fat thickness.

The research, conducted at the Centro APTA Bovinos de Corte, Instituto de Zootecnia, examined data from Nelore cattle across multiple generations, focusing on animals selected for growth traits like weight at 378 days (W378) for males and weight at 550 days (W550) for females. Ultrasound measurements were taken at 12 and 18 months to assess LMA and backfat thickness (BF) and rump fat thickness (RF).

The study's primary aim was to estimate heritability and genetic correlations between these traits. Heritability indicates the proportion of a trait's variation due to genetic factors, while genetic correlations reveal the extent to which selecting for one trait influences another. High heritability suggests that a trait can be effectively improved through selective breeding.

LMA Heritability: Both 12 and 18 months showed high heritability (0.47 and 0.40, respectively), indicating good potential for improvement through selection.
Fat Thickness: Heritability ranged from 0.37 to 0.29, suggesting moderate genetic influence.
Age Matters: Genetic correlations for LMA between 12 and 18 months were high (0.95), indicating consistent genetic control across ages.

Importantly, the study found low genetic correlations between LMA and subcutaneous fat measures at both ages. This key finding suggests that selecting for increased LMA won't necessarily lead to increased fat deposition, addressing a major concern for producers.

The Bottom Line: Strategic Selection for a Better Beef Product

The results of this research offer valuable insights for Nelore cattle breeders. The high heritability of LMA suggests that selection for increased muscle mass can be effective, leading to tangible improvements in carcass value. Furthermore, the low genetic correlations between LMA and subcutaneous fat provide reassurance that these gains can be achieved without compromising meat quality through excessive fat deposition.

The study also highlights the potential for earlier evaluation. The strong genetic correlation for LMA between 12 and 18 months suggests that ultrasound measurements taken at a younger age can provide reliable information for selection decisions, accelerating genetic progress and allowing producers to make earlier breeding choices.

By focusing on growth traits and incorporating ultrasound evaluation of carcass characteristics, producers can strategically select animals that not only grow efficiently but also yield high-value carcasses with optimal muscle-to-fat ratios. This data-driven approach can lead to increased profitability and a more desirable product for consumers.

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: 10.1590/s1516-35982012000600016, Alternate LINK

Title: Selection For Higher Body Weight In Nelore Cattle Is Effective In Achieving An Increase Of Longissimus Muscle Area Without Reducing Subcutaneous Fat Thickness

Subject: Animal Science and Zoology

Journal: Revista Brasileira de Zootecnia

Publisher: FapUNIFESP (SciELO)

Authors: Tiago Roque Pinheiro, Maria Eugênia Zerlotti Mercadante, Lucia Galvão De Albuquerque, Sarah Figueiredo Martins Bonilha, Fábio Morato Monteiro

Published: 2012-06-01

Everything You Need To Know

Why is longissimus muscle area (LMA) so important?

The longissimus muscle area (LMA) is the primary indicator of muscling and it directly translates to increased yield in Nelore cattle. Maximizing LMA is a crucial goal for cattle ranchers because it enhances carcass value. The research indicated high heritability for LMA, indicating that there is good potential for improvement through strategic selection. This implies that breeders can effectively increase muscle mass through selective breeding, directly impacting profitability.

What does heritability mean and why is it important in cattle breeding?

Heritability refers to the proportion of variation in a trait, such as longissimus muscle area (LMA) or fat thickness, that is due to genetic factors. The study shows that LMA has high heritability, suggesting that selective breeding can effectively improve muscle mass in Nelore cattle. Fat thickness, on the other hand, has a moderate genetic influence. Understanding heritability allows breeders to make informed decisions about which traits to prioritize when selecting animals for breeding to optimize carcass value and meat quality.

What are genetic correlations, and why is the research finding about them so important?

Genetic correlations reveal the extent to which selecting for one trait influences another. The study found low genetic correlations between longissimus muscle area (LMA) and subcutaneous fat measures in Nelore cattle. This is significant because it suggests that selecting for increased muscle mass (LMA) will not necessarily result in increased fat deposition. This finding addresses a major concern for producers who want to improve carcass value without negatively affecting meat quality or consumer appeal. This allows breeders to focus on increasing muscle mass without worrying about excessive fat.

What was the significance of evaluating Nelore cattle at both 12 and 18 months of age?

The study evaluated Nelore cattle at 12 and 18 months of age to assess longissimus muscle area (LMA) and backfat thickness. Evaluating animals earlier, at 12 months, could accelerate genetic progress by enabling earlier selection and breeding decisions. Genetic correlations for LMA between these ages were high (0.95), indicating consistent genetic control across ages. This suggests that selection decisions made at 12 months are likely to be predictive of carcass traits at 18 months, offering an opportunity for earlier and more efficient breeding decisions.

What is strategic selection, and how does it relate to this research?

Strategic selection involves choosing Nelore cattle for breeding based on specific traits, such as growth traits and longissimus muscle area (LMA), to improve carcass value and meat quality. The research showed that selecting for increased LMA won't lead to increased fat deposition. This allows for the selection of animals with superior muscle mass without compromising meat quality due to excessive fat. This approach helps producers make informed decisions to enhance the value of their herds by balancing muscle development with fat management.