Infrequent self-fed Lupin supplementation in yearling steers grazing enhanced Lotus uliginosus cv. INIA Gemma pastures on Basaltic soils

Abstract

This study evaluated the effects of infrequent, self-fed winter supplementation with whole lupin grain on the growth performance of yearling Hereford steers grazing improved native pasture based on Lotus uliginosus cv. INIA Gemma in basaltic soils. The trial lasted 98 days (August–November 2022) and was conducted at the Glencoe Experimental Unit (INIA Tacuarembó), using a completely randomised design with two treatments (no supplementation; SL) and 1% LW supplementation (CL) and two replicates. Thirty-two steers (initial liveweight-LW: 302 kg) were assigned to treatments based on body weight. The CL group showed significantly higher daily liveweight gains (1440 vs. 700 g/day; P<0.01), final LW (441 vs. 375 kg; P<0.01), and productivity per hectare (382 vs. 186 kg LW/ha; P<0.01), with a feed conversion efficiency of 5.1 kg of lupin grain per additional kg of LW gain. Forage height pre- and post-grazing was significantly higher in CL (5.5 vs. 4.6 cm and 4.4 vs. 3.7 cm, respectively; P<0.05), although no major differences were observed in pre- and post-grazing forage quantity, structure, or nutritional value. The botanical composition was slightly affected by supplementation. Supplemented steers spent less time grazing and more time resting. These findings support the value of combining improved Lotus uliginosus cv. INIA Gemma pastures with lupin supplementation to accelerate growth and improve productivity in semi-extensive beef systems in the Basaltic region.