Rl. Reid et al., EVALUATION OF BRASSICAS IN GRAZING SYSTEMS FOR SHEEP .1. QUALITY OF FORAGE AND ANIMAL PERFORMANCE, Journal of animal science, 72(7), 1994, pp. 1823-1831
Four years of grazing trials were conducted with Brassica forages to e
valuate their chemical composition and effect on ADG of fattening lamb
s and breeding ewes in late fall. Brassicas tested included kales (Bra
ssica oleracea L. var. acephala DC), turnips (B. rapa L.), and a chine
se cabbage hybrid (B. rapa L. x B. pekinensis [Lour.] Rupr.). Daily ga
ins of lambs varied widely among years (19 to 330 g/d); ADG on Brassic
as were, however, generally higher than on stockpiled Kentucky 31 tall
fescue (Festuca arundinacea Schreb.) or orchardgrass (Dactylis glomer
ata L.)-red clover (Trifolium pratense L.) pastures grazed at the same
time. In 1 yr, dietary supplementation of lambs grazing a hybrid turn
ip (Forage Star) with iodine and copper oxide needles improved (P < .0
5) ADG; however, there was no effect on gains in two later years. In 2
yr, lambs showed higher ADG on Tyfon chinese cabbage hybrid (241 and
330 g/d) than on Forage Star turnip (197 and 275 g/d) or stockpiled gr
ass-clover (135 and 233 g/d), but yield of Tyfon was lower. Indication
s that supplementary hay improved ADG of lambs and ewes were not confi
rmed in the final year, in which hay increased (P < .05) ADG of lambs
in the first 3 wk of grazing Brassicas but decreased gains later. Thyr
oid weights were increased (P < .01) consistently in all trials on Bra
ssicas, but enlargement was modest and not related to ADG. Brassica fo
rages provided high yields (5.6 to 10.5 t/ha) of DM in the late fall t
o early winter period, with high carrying capacity for sheep but large
variability in ADG.