The effect of continuous or rotational stocking on the intake and live-weight gain of cattle co-grazing with sheep on temperate pastures

Two experiments were conducted to determine if type of stocking system infl uenced the intake and live-weight gain (LWG) of cattle co-grazed with sheep on sown ryegrass/white clover pasture. In experiment 1 (134 days), yearling heifers (no. = 9) plus ewe hoggets (no . = 27) were co-grazed (1 : 1 M-0.75) using continuous (C-CS) or rotational (R-CS) stocking. In experiment 2 (126 days), a cattle alone (no. = 9) trea tment was included under each stocking system (C-C and R-C). Initial live w eight of heifers was 266 (s.e. 4.5) and 232 (s.e. 4.4) kg and that of hogge ts was 54 (s.e. 0.9) and 47 (s.e. 0.7) kg in experiments 1 and 2, respectiv ely. In both experiments, the area offered daily to R-CS group was manipula ted to promote a weekly live-weight change in sheep similar to that on the C-CS treatment. C-C cattle in experiment 2 were grazed at similar sward sur face height (SSH) to C-CS, and R-C cattle at similar pre- and post-grazing SSH to R-CS. SSH was measured daily on all treatments and regulated on the continuously stocked treatments by addition and removal of non-experimental animals. Organic matter intake (OMI) was determined from the ratio of n-al kanes in faeces and herbage. Animals were weighted weekly. Mean SSH on continuously stocked pastures was 5.10 (s.e. 0.03) and 4.26 (s. e. 0.02) cm for C-CS in experiments 1 and 2, respectively, and 4.27 (s.e. 0 .02) cm for C-C in experiment 2. The mean pre-and post-grazing SSH for R-CS was 15.9 (s.e. 0.12) and 5.60 (s.e. 0.07) cm, respectively in experiment 1 , and 15.2 (s.e. 0.08) and 4.82 (s.e. 0.03) cm, respectively in experiment 2. On R-C swards pre- and post-grazing SSH was 14.9 (s.e. 0.08) and 4.87 (s .e. 0.03) cm, respectively. In experiment 1, cattle continuously co-grazed with sheep grew significantl y more slowly than those rotationally co-grazed with sheep (804 (s.e. 41.6) v. 1039 (s.e. 47.7) g/day, P < 0.01). Sheep LWG did not differ between sto cking treatments (150 v. 138 g, P > 0.05 for C-CS and R-CS respectively). T hese findings were confirmed in the second experiment in which C-CS cattle only grew at 0.69 of the daily LWG achieved by R-CS cattle (706 v. 1028, (s .e. 72) g/day; P < 0.05) at similar sheep LWG (155 v. 147, (s.e. 6.5) g/day respectively). LWG of C-C and R-C cattle was similar (916 v. 1022, (s.e. 7 2) g/day; P > 0.05). LWG per ha in both experiments was higher on R-CS than on C-CS treatments, and on cattle alone than on CS treatments. Treatment e ffects on OMI and final fasted live weight were similar in pattern to LWG. It is suggested that the observed disadvantage to cattle when co-grazed wit h sheep under continuous stocking and the lack of effect when rotationally co-grazed reflected a difference in the two stocking systems in providing o pportunities for complementary/competitive use of pasture resources.