Suplementación con grano de lupino (Lupinus angustifolius) en régimen de autoconsumo a terneras pastoreando raigrás: Efecto sobre consumo, la selección, y el comportamiento animal

The present study was conducted during the winter season, between July 6 and September 27, at the Mario A. Cassinoni Experimental Station (E.E.M.A.C.) of the Faculty of Agronomy at the University of the Republic, located in the department of Paysandú, Uruguay. The objective of this study was to evaluate the effect of supplementation with lupin grain (Lupinus angustifolius) and the method of supply (daily or self-feeder) on intake and animal behavior in heifer calves grazing winter forages under restricted forage allowance.

Thirty-six Hereford heifers, with an initial body weight (BW) of 174 kg ± 18 kg, were blocked by BW at the beginning of the pre-experimental period (light, medium, and heavy) and randomly assigned within each block to one of three treatments: (1) ryegrass grazing without supplementation (CONTROL); (2) ryegrass grazing plus daily supplementation with broken lupin grain at a rate of 1 kg DM/100 kg BW (DS); (3) ryegrass grazing plus supplementation with broken lupin grain in self-feeders with ad libitum grain availability (AC). Each treatment consisted of three replicates, with each replicate including four heifers grazing an independent plot. The animals grazed in weekly strips with a forage allowance of 2.5% BW and were taken daily to drink water.

Supplementation improved dry matter (DM) intake regardless of the treatment, compared to the control treatment. An increase of 0.88% in DM intake (%BW) was observed in the daily supplementation treatment, surpassing the control. Moreover, this difference was even greater in the AC treatment.

The three treatments had equal conditions in terms of available forage and botanical composition (p-value > 0.05). However, significant differences were observed in the residual forage as well as in forage utilization at the end of the 7-day grazing period, the latter being greater in the control treatment. Based on these results, the effect can be classified as an addition-substitution response.

Furthermore, significant differences (p-value < 0.05) were found in the time spent grazing, with the control group spending the most time, followed by the daily supplementation treatment, and lastly, the self-feeding treatment.