Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/24/2000
Publication Date: 10/1/2000
Citation: GROSZ, M.D., MACNEIL, M.D. PUTATIVE QUANTITATIVE TRAIT LOCUS AFFECTING BIRTH WEIGHT ON BOVINE CHROMOSOME 2. JOURNAL OF ANIMAL SCIENCE. 2000. v. 79. p. 68-72. Interpretive Summary: Dystocia is a significant problem in both beef and dairy industries. In beef cattle production, the effects of dystocia are felt both in death or reduced performance of the calf as well as diminished re-breeding potential in the dam. However, selection for lower birth weight will lead to lower growth potential (and selection for growth will lead to increased dystocia) due to the genetic correlation between pre- and postnatal growth. Identifying genes affecting birth weight, but not growth at other developmental stages will provide tools to more accurately describe the genetic merit of animals to be used for breeding stock. Coupled with marker assisted selection (using molecular analyses to identify animals to be used for breeding), exploitation of loci such as has been presented in this paper can provide a mechanism to reduce birth weight, and thus, incidence and severity of dystocia without affecting postnatal growth.
Technical Abstract: A genome scan for chromosomal regions influencing birth weight was performed using 151 progeny from a single Hereford x composite bull and 170 microsatellite markers spanning 2.497 Morgans on 29 bovine autosomes. A quantitative trait locus (QTL) was identified at the telomeric end of bovine chromosome 2 (maximum effect at 114 cM) accounting for approximately 2.8 kg of birth weight or 0.64 residual standard deviations (after adjustment for sex of calf, age of dam, and breed of dam). Growth from birth to weaning was not significantly affected by any genes in this region. The presence of this QTL within a resource herd comprised of breeds common to the Northern Great Plains provides an opportunity to initiate marker assisted selection (MAS) to reduce birth weight with minimal effect on postnatal growth, thus reducing the amount and degree of dystocia, and lessening the economic loss associated with calving difficulty. In addition, this finding indicates that significant genetic variation for birth weight (and presumably other production-related traits) exists within herds comprised of strictly Bos taurus germplasm.