Efecto de la suplementación con grano de lupino (Lupinus angustifolius) en régimen de autoconsumo sobre la performance de novillos pastoreando sorgo forrajero

The presented work was carried out at the Mario A. Cassinoni Experimental Station (EEMAC) of the Faculty of Agronomy, University of the Republic, located in the department of Paysandú, Uruguay. It was conducted between January 10 and March 7, 2023, with the aim of evaluating the effect of supplementation with broken lupin grain (Lupinus angustifolius) under a self-feeding regime on the productive performance and feed efficiency of Hereford steers grazing on forage sorghum. Sixty-four Hereford steers weighing 246 ± 38 kg of live weight (LW) were blocked by live weight (light, medium, and heavy) and randomly assigned within each block to one of two treatments: forage sorghum grazing without supplementation (control, C); grazing on sorghum plus supplementation with broken lupin grain offered ad libitum (supplemented, S). Each treatment consisted of 3 replicates, each composed of 10-11 steers grazing an independent plot. The performance variables evaluated were weight gain, dry matter intake, feed conversion efficiency, ingestive behavior, and consumption pattern. The animals grazed in weekly strips with a forage allocation of 8% of LW, being moved daily to a pen with water and shade from 10:00 to 17:00 h, during which time they had ad libitum access to lupin. Supplementation did not affect the height and botanical composition (p-value>0.05) of the offered forage. Grazing activity was not significantly affected, and no differences were detected in forage utilization. Supplementation improved average daily gain (ADG) (0.971 vs. 0.554 kg/a/d, p-value>0.05), resulting in a supplementation response of 0.417 kg/d more for the animals consuming lupin and a supplement conversion efficiency (SCE) of 6.8:1. Supplement intake under the self-feeding regime was 1.03% of live weight.