Efecto de la suplementación con grano de lupino y su procesamiento sobre la performance de novillos Hereford pastoreando sorgo forrajero durante el verano

The work presented was carried out in the summer season, between December 30, 2021 and March 7, 2022, at the Mario A. Cassinoni Experimental Station (E.E.M.A.C.) of the Faculty of Agronomy, University of the Republic, located in the department of Paysandú, Uruguay. Fifty-three (53) Hereford steers of 270 kg ± 52 kg LW at a stocking rate of 5.9 UG/ha, randomly distributed and stratified according to their weight, were assigned to three treatments in a randomized block design (DBCA). The witness treatment (T) group that were only in night grazing in weekly strips of forage sorghum BMR assigned to 8% of live weight, being confined with water and shade while the maximum ITH schedule, from 10:00 to 17:00; a second whole lupin treatment (E) where the animals were in the same conditions as the witness with the difference that during the confinement time, they were supplemented at a rate of 1% of the daily LW with whole grain of Lupinus angustifolius; and the third hammermill lupin treatment (Q) in the same way as the previous one with the only difference that the grain was offered hammermill. The effect of supplementation was studied, this being the average daily gain (ADG) of the whole and hammermill treatments, compared to the witness treatment, the result being 0.723 kg/d more for the supplemented animals. The three treatments were found in equal conditions of available forage, height and botanical composition (p-value> 0.05), in turn, no differences were recorded in the remnants between treatments, so the response to supplementation was additional. The ADGs were 0.905a - 0.999a - 0.229b kg/a/d for treatments E, Q and T respectively, resulting in a conversion efficiency (ECS) of 4.4:1. The effect of grain processing did not show impacts on ADG, these being non-significant between E and Q (p-value>0.05) or in ECS 4.6 and 4.1, respectively. By counting and weight of grains/fragments in feces, it was determined for treatment E and Q, 7.8 and 0.14% of grain in feces, these values ​​being significantly different from each other (p-value<0.05), In the case of treatment E, it was found that the weight of the dry grain offered and the weight of the dry grain collected in feces differ statistically, stating a partial digestion of 60%. Finally, the consumption rate of the supplement measured as a % of  offered and as kg in the first hour did not differ between the supplemented treatments (p-value>0.05).