Grazing Preference of Dairy Cows and Pasture Productivity for Different Cultivars of Perennial Ryegrass under Contrasting Managements
Departamento de Ciencias Agropecuarias y Acuícolas, Facultad de Recursos Naturales, Universidad Católica de Temuco, Campus Norte, Rudecindo Ortega 02950, Temuco 4780000, Chile
Rothamsted Research, Sustainable Agriculture Sciences, North Wyke, Okehampton, Devon EX20 2SB, UK
Facultad de Ciencias Agrarias, Instituto de Producción Animal, Universidad Austral de Chile, Campus Isla Teja, Valdivia 5090000, Chile
CIA-CENEREMA, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Campus Isla Teja, Valdivia 5090000, Chile
Graduate School, Faculty of Agricultural Sciences, Universidad Austral de Chile, Campus Isla Teja, Valdivia 5090000, Chile
Author to whom correspondence should be addressed.
Received: 13 April 2019 / Revised: 10 May 2019 / Accepted: 16 May 2019 / Published: 20 May 2019
Increasing soluble sugars in pasture species can lead to an improved nutrient use efficiency in the rumen and a greater digestibility of forage, which in turn might increase pasture intake. However, this improvement in nutritional value must not be at the expense of pasture productivity; the amount of nutrients harvested is a relevant factor in ruminant grazing systems’ efficiency. Therefore, we tested four different cultivars of perennial ryegrass (two selected for greater soluble sugar content and two standard cultivars) submitted to two contrasting managements (one aimed at improving sugar content and one with the opposite intended effect) for their effects on pasture productivity (by cutting herbage every time the plots reached the target number of leaves per tiller, i.e., two or three) and the grazing preference of dairy cows (six cows grazed for up to 5 hours, in an experimental area with three plots for each of the eight treatments) in spring, summer and autumn. We found that high sugar grasses had lower annual dry matter productivity and no preference was shown by cows, although the agronomic management aimed at reducing sugar concentration enhanced crude protein concentration and increased the herbage harvested (greater preference) in the three seasons, and the time spent grazing in autumn.