Efecto del procesamiento del grano de lupino sobre la respuesta a la suplementación de terneros pastoreando raigrás: Crecimiento, utilización del forraje y eficiencia de conversión del suplemento

The experiment was carried out at the Intensive Meat Production Unit (UPIC) of the Estación Experimental “Dr. Mario A. Cassinoni”, Facultad de Agronomía, in the department of Paysandú. The experimental period took place from June 26, 2024, to September 3 of the same year, totaling 70 days. The aim of the study was to evaluate the effect of lupine supplementation and its processing on animal production, as well as feed use efficiency in calves grazing on ryegrass cv Selva with restricted forage supply (2.5% DM). A total of 33 castrated Hereford calves born in the spring of 2023, weighing 154.8 ± 10.4 kg, were evaluated. The calves were blocked by live weight, forming 3 groups, and randomly assigned to 9 groups, which were then assigned to one of 3 treatments (Control: no supplementation; SLQ: supplementation with cracked lupine; and SLE: supplementation with whole lupine), resulting in 3 replicates per treatment with 4 animals each. A rotational strip grazing was carried out with 7 days of occupation, varying the plot area according to the available dry matter and the last live weight recorded for each replication. The lupin grain (Lupinus angustifolius) used to supplement the animals was supplied daily at a rate of 1% of live weight on a dry matter basis, adjusted according to the last live weight of each replication. Animal performance, measured as average daily live weight gain, was significantly higher for supplemented animals, not varying significantly according to the degree of grain processing, recording values of 0.44 kg/day, 0.84 kg/day, and 0.94 kg/day for the control, whole, and cracked treatments, respectively. The conversion efficiency achieved was 4.54 and 3.92:1 for SLE and SLQ, respectively, with no significant differences between them (p=0.498). Dry matter intake from forage showed significant differences (p=0.0141) between supplemented animals and controls, showing a substitution effect of forage by supplement, affecting pasture utilization where there was a 14% lower intake for supplemented animals.