Description
Globally, extensive pastoral grazing systems are facing multiple pressures, including to address emerging public concerns about environmental impact and animal well-being. This may require new regulatory constraints to be met, while maintaining the economic viability of the systems. One novel approach to addressing these challenges is to capitalize on naturally occurring differences in livestock behaviors, specifically differences in grazing personalities, to assist the production systems deliver more effective and responsible use of rangelands. Herbivores may exhibit consistent grazing behaviors over time and across spatial contexts, which differ among individuals and between groups leading to distinctive grazing patterns known as grazing personalities. A study conducted in steep and rugged rangelands of New Zealand with GPS-tracked cows (n = 303) that were genotyped for variation in a ‘grazing gene’, the glutamate metabotropic receptor 5 gene (GRM5), revealed genetic associations (P < 0.02) and trends towards associations (P < 0.1) with home range, movement tortuosity, elevation range and horizontal distance travelled. In an average herd, two GRM5 genotypes associated with medium-sized home ranges accounted for 72% of cows, another two genotypes associated with the largest home ranges accounted for 16% and the remaining 12% had the genotype with the smallest home range. Furthermore, genotypes with the largest home range had the least ‘crooked’ movement tortuosity. Here, we propose changing the proportion of GRM5 genotypes in cattle herds to better match the collective grazing patterns within steep and rugged rangelands. For example, increasing the proportion of GRM5 genotypes with largest home ranges and straightest movement tortuosity may lead to decreasing grazing frequency of vegetation at several scales (e.g., individual plants, plant communities and ecological sites) and better utilization of the available forage. We highlight opportunities of a GRM5 grazing personality approach to improving collective grazing patterns of beef cattle in steep and rugged rangelands to enable more sustainable pastoral grazing systems.
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Opportunities of Grazing Personality Genetics for Steep and Rugged Rangelands
Globally, extensive pastoral grazing systems are facing multiple pressures, including to address emerging public concerns about environmental impact and animal well-being. This may require new regulatory constraints to be met, while maintaining the economic viability of the systems. One novel approach to addressing these challenges is to capitalize on naturally occurring differences in livestock behaviors, specifically differences in grazing personalities, to assist the production systems deliver more effective and responsible use of rangelands. Herbivores may exhibit consistent grazing behaviors over time and across spatial contexts, which differ among individuals and between groups leading to distinctive grazing patterns known as grazing personalities. A study conducted in steep and rugged rangelands of New Zealand with GPS-tracked cows (n = 303) that were genotyped for variation in a ‘grazing gene’, the glutamate metabotropic receptor 5 gene (GRM5), revealed genetic associations (P < 0.02) and trends towards associations (P < 0.1) with home range, movement tortuosity, elevation range and horizontal distance travelled. In an average herd, two GRM5 genotypes associated with medium-sized home ranges accounted for 72% of cows, another two genotypes associated with the largest home ranges accounted for 16% and the remaining 12% had the genotype with the smallest home range. Furthermore, genotypes with the largest home range had the least ‘crooked’ movement tortuosity. Here, we propose changing the proportion of GRM5 genotypes in cattle herds to better match the collective grazing patterns within steep and rugged rangelands. For example, increasing the proportion of GRM5 genotypes with largest home ranges and straightest movement tortuosity may lead to decreasing grazing frequency of vegetation at several scales (e.g., individual plants, plant communities and ecological sites) and better utilization of the available forage. We highlight opportunities of a GRM5 grazing personality approach to improving collective grazing patterns of beef cattle in steep and rugged rangelands to enable more sustainable pastoral grazing systems.
