ORCID

https://orcid.org/0000-0003-2788-2210

Department

Biological Sciences

Year of Study

2

Full-time or Part-time Study

Full-time

Level

Postgraduate

Presentation Type

Oral Presentation

Supervisor

Dr. Deirdre Purfield

Supervisor

Dr. Craig Murphy

Supervisor

Dr. Ross Evans

Abstract

Background

Rumen methanogenesis is the single most significant source of anthropogenic methane (CH4) emissions. This research aimed to analyse CH4 data recorded by GreenFeed systems by assessing the repeatability of such phenotypic measures, estimating the heritability of CH4, and generating CH4 estimated breeding values (EBVs) for inclusion in the national breeding index.

Methods

CH4 measurements were recorded on 979 cattle for 20 to 83 days using GreenFeed machines, resulting in 211,136 individual CH4 observations. The phenotypic repeatability of CH4 was estimated for six different averaging periods using a linear mixed model. Univariate repeatability animal models in DMU were used to estimate CH4 and residual CH4 (RCH4) heritability parameters. EBVs for both CH4 and RCH4 were estimated using MiX99. EBV validation was completed using the most recent third of animals and linear regression was used to estimate the bias of the EBVs.

Results

Repeatability of CH4 increased as the length of the averaging period increased, ranging from 0.16 within a day to 0.69 in a 15-day averaging period in steers. Heritability estimates of both CH4 (0.08 – 0.31) and RCH4 (0.09 – 0.39) increased as the duration of the averaging period increased. RCH4 EBVs were more consistent in dispersion bias than CH4 EBVs across the averaging periods, which suggests that RCH4 may be better suited for inclusion within the national breeding index.

Conclusion

With respect to both repeatability and heritability of CH4 and RCH4, animals are required to spend a minimum of 10 days on test to produce EBVs from GreenFeed measurements.

Keywords:

Methane, Greenhouse gas, beef cattle, genetics, GreenFeed

Start Date

June 2022

End Date

June 2022

COinS
 
Jun 14th, 12:15 PM Jun 14th, 12:30 PM

Clearing the air between methane and commercial beef cattle in Ireland

Background

Rumen methanogenesis is the single most significant source of anthropogenic methane (CH4) emissions. This research aimed to analyse CH4 data recorded by GreenFeed systems by assessing the repeatability of such phenotypic measures, estimating the heritability of CH4, and generating CH4 estimated breeding values (EBVs) for inclusion in the national breeding index.

Methods

CH4 measurements were recorded on 979 cattle for 20 to 83 days using GreenFeed machines, resulting in 211,136 individual CH4 observations. The phenotypic repeatability of CH4 was estimated for six different averaging periods using a linear mixed model. Univariate repeatability animal models in DMU were used to estimate CH4 and residual CH4 (RCH4) heritability parameters. EBVs for both CH4 and RCH4 were estimated using MiX99. EBV validation was completed using the most recent third of animals and linear regression was used to estimate the bias of the EBVs.

Results

Repeatability of CH4 increased as the length of the averaging period increased, ranging from 0.16 within a day to 0.69 in a 15-day averaging period in steers. Heritability estimates of both CH4 (0.08 – 0.31) and RCH4 (0.09 – 0.39) increased as the duration of the averaging period increased. RCH4 EBVs were more consistent in dispersion bias than CH4 EBVs across the averaging periods, which suggests that RCH4 may be better suited for inclusion within the national breeding index.

Conclusion

With respect to both repeatability and heritability of CH4 and RCH4, animals are required to spend a minimum of 10 days on test to produce EBVs from GreenFeed measurements.