Heritability and genetic correlations between enteric methane production and concentration recorded by GreenFeed and sniffers on dairy cows.

To reduce methane (CH) emissions of dairy cows by animal breeding, CH measurements have to be recorded on thousands of individual cows. Currently, several techniques are used to phenotype cows for CH, differing in costs and applicability. However, there is uncertainty about the agreement between techniques. To judge the similarity and repeatability between measurements of different recording techniques, the repeatability, heritability, and genetic correlation are useful metrics. Therefore, our objective was to estimate (1) the repeatability and heritability for CH and carbon dioxide production recorded by GreenFeed (GF) and for CH and carbon dioxide concentration measured by cost-effective but less accurate sniffers, and (2) the genetic correlation between CH recorded with these 2 different on farm and high throughput techniques. Data were available from repeated measurements of CH production (grams/day) by GF units and of CH concentration (ppm) by sniffers, recorded on commercial dairy farms in the Netherlands. The final data comprised 24,284 GF daily means from 822 cows, 170,826 sniffer daily means from 1,800 cows, and 1,786 daily means from 75 cows by both GF and sniffer (in the same period). Additionally, CH records were averaged per week. For daily and weekly mean GF CH the heritabilities were 0.19 ± 0.02 and 0.33 ± 0.04, and for daily and weekly mean sniffer CH the heritabilities were similar and were 0.18 ± 0.01 and 0.32 ± 0.02, respectively. Phenotypic correlations between GF CH production and sniffer CH concentration were moderate (0.39 ± 0.03 for daily means and 0.37 ± 0.05 for weekly means). However, genetic correlations were high; 0.71 ± 0.13 for daily means and 0.76 ± 0.15 for weekly means. The high genetic correlation indicates that selection on low CH concentrations (ppm) recorded by the cost-effective sniffer method, will result in reduced CH production (grams/day) as recorded with GF.