Grazing behaviour of dairy cows on simple and diverse swards in summer and autumn

摘要

Increasing the proportion of dicotyledonous species such as herbs and legumes in dairy pastures may increase herbage dry matter intakes through ease of prehension. Simple swards consisting of either standard perennial ryegrass, high sugar ryegrass ortall fescue cultivars with white clover were established at the Lincoln University research dairy farm. Diverse swards were created by adding chicory and plantain to all mixtures, plus prairie grass and red clover to the perennial ryegrass, and praire grass and lucerne to the tall fescue. Grazing behaviour of cows during a two hour grazing session was monitored in summer and autumn. In summer, Diverse swards had a greater compressed sward surface height, lower mass and bulk density. Cows grazing Simpleswards achieved a greater bite rate (49.3 vs 43.8 bites/min respectively (P < 0.05)). In autumn, all pasture swards had lower mass and contained a higher proportion of grass species than in summer. Bite rate was greater on Diverse compared with Simple swards (60.3 vs 54.3 bites/min respectively (P < 0.05)). Lower bite rate on Simple swards was compensated for by increasing grazing duration (P < 0.001). Sward type influenced bite rate adaptations.