Efecto de la intensidad de pastoreo sobre la respuesta productiva a la suplementación con grano de lupino en terneros Hereford pastoreando en raigrás Bill Max durante invierno

The experiment was conducted at the Intensive Meat Production Unit (UPIC) of the Dr. Mario A. Cassinoni Experimental Station, Faculty of Agronomy, located at Km 363 of national route No. 3, in the department of Paysandú. The experimental period was from July 7 to September 15, 2020. The objective was to evaluate different types of supplements and their effect on animal performance in calves grazing a ryegrass pasture cv Bill Max. We worked with 48 Hereford calves born in spring 2019 at approximately 8 months of age. At the start of the experiment they had an average weight of 148.3 ± 25.8 kg. The 48 animals were blocked by live weight (3 blocks) and randomly assigned within each block, one of four treatments. Differing in supplementation and forage allocation, each treatment consisted of three replicates of 4 calves each grazing an independent plot. The grazing was carried out in strips with 7 days of permanence, adjusting weekly the PA in each plot according to the availability of dry matter of ryegrass and the weight of the animals. As for the supplementation (offered at 1% of the PV), split lupine grain (Lupinus angustifolius) was used. The treatments grazed with a forage supply of 2.5 kg DM per 100 kg of BW and 5 kg DM per 100 kg of BW. The supplement was fed to the respective treatments in the plots in the morning. The amount on a dry basis was adjusted weekly according to the change in animal weights and DM content of the supplement. Animal performance, measured as average daily weight gain in the supplemented animals was 1.12 kg/day and 0.48 kg/day in the non-supplemented animals, with no significant difference found between the forage allocation variable. The difference in forage availability between treatments and supplement consumption was not significant either. In terms of supplement conversion efficiency, there were no significant differences between treatments. The probability of finding the animals grazing differed in the treatments with supplement, being these the animals that dedicated less time to the activity, while in the resting activity, the supplemented animals had differences with respect to the controls, with more time dedicated to it. The ruminating activity had differences, being the treatments supplemented with lupine the ones that had more time dedicated to this activity. The grazing was carried out in strips with 7 days of permanence, adjusting weekly the PA in each plot according to the availability of dry matter of ryegrass and the weight of the animals. As for the supplementation (offered at 1% of the PV), split lupine grain (Lupinus angustifolius) was used. The treatments grazed with a forage supply of 2.5 kg DM per 100 kg of BW and 5 kg DM per 100 kg of BW. The supplement was fed to the respective treatments in the plots in the morning. The amount on a dry basis was adjusted weekly according to the change in animal weights and DM content of the supplement. Animal performance, measured as average daily weight gain in the supplemented animals was 1.12 kg/day and 0.48 kg/day in the non-supplemented animals, with no significant difference found between the forage allocation variable. The difference in forage availability between treatments and supplement consumption was not significant either. In terms of supplement conversion efficiency, there were no significant differences between treatments. The probability of finding the animals grazing differed in the treatments with supplement, being these the animals that dedicated less time to the activity, while in the resting activity, the supplemented animals had differences with respect to the controls, with more time dedicated to it. The ruminating activity had differences, being the treatments supplemented with lupine the ones that had more time dedicated to this activity.