Putative quantitative trait locus affecting birth weight on bovine chromosome 2

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Livestock Breeding

Background:

• Birth weight is a critical trait in beef cattle, influencing calving ease and calf survival.
• Genetic factors play a significant role in determining birth weight, but specific chromosomal regions are not fully understood.
• Reducing dystocia and associated economic losses is a key objective in beef production.

Purpose of the Study:

• To perform a genome scan to identify chromosomal regions associated with birth weight in cattle.
• To locate quantitative trait loci (QTL) influencing birth weight in a Hereford x composite population.
• To assess the potential for marker-assisted selection to manage birth weight and calving difficulty.

Main Methods:

• Utilized 151 progeny from a Hereford x composite bull and 170 microsatellite markers across 29 bovine autosomes.
• Conducted a genome scan to analyze the genetic architecture of birth weight.
• Adjusted birth weight data for sex of calf, age of dam, and breed of dam.

Main Results:

• A significant QTL for birth weight was identified on the telomeric end of bovine chromosome 2 (at 114 cM).
• This QTL explained approximately 2.8 kg of birth weight variation.
• No significant effect of this QTL on growth from birth to weaning was detected.

Conclusions:

• The identified QTL on chromosome 2 offers a target for marker-assisted selection to reduce birth weight and calving difficulty.
• Implementing selection based on this QTL could mitigate economic losses from dystocia without negatively impacting postnatal growth.
• Significant genetic variation for birth weight exists within commercially relevant Bos taurus cattle populations.