# Gene-Polymorphism Effects on Growth Efficiency in the Kalmyk Breed of Central Asia

## TL;DR

This study identifies a gene variant in Kalmyk cattle that improves growth without increasing fat, helping breeders select better beef-producing animals.

## Contribution

The study identifies a specific SNP in the ELOVL6 gene associated with improved growth traits in Kalmyk cattle without increasing fatness.

## Key findings

- The AG genotype of g.133528A>G in ELOVL6 is linked to higher live weight and better body measurements in Kalmyk heifers.
- The identified SNP does not significantly affect backfat thickness or muscle depth, maintaining the breed's lean phenotype.
- The AG genotype could serve as a marker for marker-assisted breeding to improve beef productivity.

## Abstract

Improving meat quality and increasing beef productivity are important tasks for modern animal breeding. In this study, we focused on Kalmyk cattle, a common beef breed in Central Asia. We investigated two specific genes that may influence fat accumulation and body growth. By analyzing genetic material from young heifers and comparing it with their growth indicators, we discovered that animals with one specific gene variant showed better weight gain and body development. These results help farmers identify and select the most productive animals at an early age. This can lead to more efficient breeding, better beef quality, and ultimately benefit both producers and consumers.

Background/Objectives: Understanding the genetic basis of growth and fat deposition is crucial for improving beef productivity in Kalmyk cattle, a breed well adapted to the extreme climatic conditions of Kazakhstan. The present study aimed to determine the effects of single-nucleotide polymorphisms (SNPs) in the CRTC2 and ELOVL6 genes on intramuscular fat content and to evaluate their associations with growth and meat quality traits in 18-month-old Kalmyk heifers raised under different environmental conditions. Methods: A total of 400 clinically healthy Kalmyk heifers (200 from LLP “Qazaq Asyldary” and 200 from LLP “Agrofirma Turikpen”) were examined. All animals originated from closed breeding herds, and only unrelated individuals without common ancestors to the third generation were included. Zootechnical measurements— live weight, withers height, chest depth, chest girth, and body length—were performed twice by a trained specialist. Backfat thickness and musculus longissimus dorsi depth were measured postmortem. Blood samples were collected for genomic DNA extraction using the GeneJET purification kit, and DNA quality was assessed by Nanodrop, Qubit, and agarose gel electrophoresis. Target fragments of CRTC2 and ELOVL6 were amplified (150–200 bp) and sequenced on an ABI 3500 system. SNP identification, allele frequencies, and genotyping were performed by alignment to the Bos taurus ARS-UCD1.2 reference genome. Statistical analyses were conducted in RStudio using linear and mixed models with “farm” as a random effect. Results: Only one informative polymorphism, g.133528A>G in ELOVL6, was detected. Three genotypes (AA, AG, GG) were observed, with the heterozygous AG genotype showing significantly higher live weight, greater body length, and improved linear measurements compared to AA and GG. No significant associations were detected with backfat thickness or muscle depth. The g.133528A>G polymorphism in ELOVL6 positively influences growth traits without increasing fatness, aligning with the naturally lean phenotype of Kalmyk cattle. Conclusions: The AG genotype may serve as a promising marker for selecting faster-growing animals in marker-assisted breeding programs.