Defoliation frequency effects on winter forage production and nutritive value of different entries of Dactylis glomerata L.

Abstract

The objective of this study was to evaluate the effect of different defoliation frequencies on winter forage production and nutritive value of improved populations of Dactylis glomerata L. Four entries: (a) base population, (b) selected plants from mass honeycomb selection (MHS), (c) selected plants from pedigree honeycomb selection (PHS), and (d) selected plants from pedigree honeycomb selection using the combined criterion CC = x ² (1 ‐ CV)/CV (PHS(CC)) were tested under four defoliation frequencies: (1) frequent, (2) moderate, (3) infrequent, and (4) control. Dry matter (DM) production under the frequent and moderate defoliation frequencies was 17% and 7% respectively more than under infrequent defoliation in the first year. However, in the second year, DM production under infrequent defoliation was 41% and 46% higher than under frequent and moderate defoliation, respectively. The DM production of the selected populations (b, c and d) of D. glomerata consistently exceeded that of the base population (a) under various defoliation frequency regimes during winter. Among the selected entries, MHS and PHS(CC) had consistently higher DM production than PHS for the two experimental years. Under increased defoliation frequencies, crude protein content significantly increased and neutral detergent fibre and acid detergent fibre significantly decreased compared with the control defoliation treatment in both years. There were no significant differences (P > 0.05) in nutritive value among the entries. Generally, DM production was more stable under infrequent defoliation, while nutritive value met the demands of small ruminants for maintenance and lactation.

Keywords:

• cool‐season grasses
• cocksfoot
• defoliation frequency
• dry matter production
• nutritive value
• defoliation management
• sward management