Effect of autumn grazing management on the performance of spring calving suckler cows and calves

The objective of this study, using spring calving suckler cows (n = 44) and their calves, was to examine the effects on animal performance of grazing as leaders (n = 11), followers (n = 11) or independently (n = 22; controls) in a rotational grazing system from 12 September to 10 November. Paddocks were divided into two equal sections and assigned to either the control or leader/follower treatments. Controls and followers moved to the next paddoc k in the rotation at the same time. The leader treatment grazed ahead of th e followers and was moved to the next paddock at the same time as the follo wers or when they had removed half the available herbage (visually assessed ). For controls, leaders and followers pre-grazing sward heights were 11.1, 10.9 and 6.8 (s.e. 0.27) cm, pre-grazing herbage yields above 4 cm were 15 20, 1448 and 883 (s.e. 62.1) kg dry matter (DM)/ha, and pre-grazing herbage in vitro DM digestibility (DMD) values were 761, 755 and 689 (s.e. 11.3) g /kg, respectively. Corresponding post-grazing sward heights were 5.6, 6.8 a nd 5.3 (s.e. 0.14) cm, post-grazing herbage yields were 486, 883 and 445 (s .e. 46.5) kg DM/ha, and post-grazing herbage DMD values were 623, 689 and 6 18 (s.e. 13.8) g/kg. Follower cows had lower (P < 0.05) milk yields than le aders and controls. For controls, leaders and followers cow live-weight cha nges were -2, -4 and -24 (s.e. 3.9 for n = 11) kg and body condition score changes were 0, 0.05 and -0.36 (s.e. 0.12) units. Corresponding calf live-w eight gains during the treatment period were 973, 1095 and 738 (s.e. 41) g/ day. Follower calves had higher (P < 0.05) gains over the subsequent winter period than leader calves, and for the combined autumn and winter periods there were no significant differences in calf live-weight gain between the three treatments. Grazing suckler cows as followers in autumn reduced live- weight and body condition score gains compared with controls and leaders wh ich were similar.