Beef cattle

Across breed regression of traits on breed specific breeding values

---

Abstract

The New Zealand dairy industry produces around two million surplus calves per annum, as such, alternative endpoints are being investigated for these calves. The New Zealand dairy industry utilises across-breed genetic evaluations, whereas the beef industry utilises within-breed evaulations. These industry evaulation structures mean that the beef and dairy industries can struggle to align their objectives or compare the performance of animals in a manner familar to them. A national level progeny test programme called the "Dairy Beef Progeny Test" (DBPT) aims to provide across-breed comparison of expected sire differences by including sires from all beef breeds represented in New Zealand to produce high quality data. This programme is used to identify sires with high genetic merit for the production of beef-on-dairy animals highly suited for the beef-finishing systems of New Zealand. The programme collects; birth weight, gestation length, calving ease/difficulty and days-to-weaning for the animals within a dairy system, then follows the animals to collect 200-, 400-, 600-day weights). Publicly available estimated breeding values (eBV) were regressed on phenotypic records collected between 2016 and 2024 by the DBPT programme using Proc Reg in SAS 9.4. The same phenotypic data and pedigree information was used within a animal model in ASReml 4.2 to obtain genetic parameter estimates and across breed eBVs for the same sires. The breed intercepts for birthweight were 37, 44, 38, 41 and 40kg for Angus, Charolais, Hereford, Shorthorn and Simmental respectively. The values indicate the expected birthweight from a calf from a bull with a zero eBV for birthweight allowing comparison across these breeds. Currently sires which enter the programme are only chosen on within breed eBVs, but this analysis will allow across breed benchmarking to take place. Within breed EBVs can be regressed on phenotypic records from progeny tests which incorporated all breeds and have good representation across years. These regression values will allow the within breed EBVs to be utilised within systems which are familiar with across breed evaluation. Slope coefficients were below the values expected for the half of EBV rule, which may be a reflection of the accuracy of the EBVs.

Keywords: 2026

How to Cite:

Sneddon, N., Archer, J., Vaughan, A. & van der Linden, D., (2026) “Across breed regression of traits on breed specific breeding values”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2287350. doi: https://doi.org/10.31274/wcgalp.24274

Rights: 1