Page 83 - NZ Hereford Magazine 2023

Figure 1: The Grazing Personality Model (GP-model) for ruminants and other large herbivores described by three main aspects: the
genotypic personality (top), regulatory system conferring personality plasticity (middle), and the phenotypic personality. For further
details please see reference website link 1 at the bottom of the page.

(GRM5) and grazing behaviours measured at the individual
level such as home range and movement tortuosity, while
trends towards association were found with elevation range
2
and horizontal distance travelled .
The daily home range and the movement tortuosity showed
statistical differences of 19 and 23% respectively, between the
genotypes with the maximum and minimum behaviours. These
genotypic differences mean an approximately 20% increase in Graham Peacock (left) and son Robert moving Hereford cows to
the explored area and a 25% increase in thoroughness of grazing. a new grazing pasture after installation of GPS collars and blood
Behavioural differences were smaller for the elevation range sampling at Orari Gorge Station.
(i.e. differences between the highest and lowest elevation in a
given day) and for horizontal distance travelled per day, reaching ranking of the mean elevation and the 85th quantile of elevation
phenotypic differences of 12% and 8% respectively. Such normalised per farm) and exploration-related behaviours (e.g.
modest values might still have important impacts for the better horizontal distance travelled, mean and maximum slope, 15th
utilisation of steep and rugged terrain because of the cumulative quantile of slope, movement tortuosity and home range). The
effect over time. Results suggested that GRM5-associated discriminant analysis – not yet published – reinforced the
behavioural differences were exacerbated in cows at and above genotype-phenotype association results and also suggested that
four years of age, and less noticeable in three-year-old cows. GRM5 variation may control several grazing behaviours.
Within Hereford herds, GRM5 genotypes were unequally
represented. For example, on average, only 16% of cows CONCLUSION
belonged to the two genotypes displaying maximum home
ranges and minimum movement tortuosity, and 72% had I studied the genetic variation of GRM5 and and found
another two genotypes displaying medium behaviours. Thus, associations and linkages with key grazing behaviours
one could expect that a gradual shift of genotypes towards observed in mature Hereford cows winter grazing steep and
increasing the proportion of those with maximum home rugged grasslands.
ranges may increase the exploration area of the herd and lead GRM5 variation was disproportionally represented in
to utilise more of the available grass and to reduce the grazing Hereford herds, offering the opportunity of improving the
pressure where cows usually congregate and tend to over- collective grazing behaviour of herds through selection.
utilise, such as near streams and water sources. Future research may focus on effectively measuring the
impact of genetic behavioural selection to improve the
Grazing behaviour linkages distribution of cattle and the use of foraging in the hill and
I finalised the research with a discriminant analysis applied to high-country grasslands of New Zealand.
a subset of the data and an array of 35 grazing behaviours.
This follow-up analysis shortlisted 15 grazing behaviours Reference website links:
that showed linkages with GRM5 variation, including elevation- 1 https://www.frontiersin.org/article/10.3389/fvets.2020.00074/full
related behaviours (e.g. elevation range, elevation gain, a 2 https://jasbsci.biomedcentral.com/articles/10.1186/s40104-022-00755-7

Year 2023 HEREFORD MAGAZINE 81