Daily Ration Intake and Performance of Semi-Feedlot Lambs in Integrated Crop-Livestock System

The objective of this study was to evaluate the effects of corn (Zea mays L.) silage intercropped with palisade grass [Urochloa brizantha (Hochst. ex A. Rich.) R. Webster cv. Marandu] and pigeonpea [Cajanus cajan (L.) Millsp.] in summer/fall and oversowing modalities of black oat (Avena strigosa Schreb.) in winter/spring on lamb’s production in semi-feedlot. Crossbred male lambs [n = 48/yr; initial BW = 27.2 ± 0.6 and 24.0 ± 0.7 kg in first and second growing season, respectively], were used in a completely randomized design. Treatments were arranged in a 2×2×2 factorial arrangement, and two silage production systems (SPS): corn+palisade grass+pigeonpea (C+PG+PP) and corn+palisade grass (C+PG); two black oat oversowing modalities (BO): drilled vs. broadcast; and two grazing cycles (GC). Animals spent the day grazing in the black oat (fixed stocking rate and rotational grazing) and during the night, they were herded into a barn, separated by treatments in collective pens, where they received concentrate and corn silage (C+PG+PP or C+PG) of their respective diets. Diets were formulated to be similar in energy and protein contents. Daily ration intake of concentrate+silage (DRI) was calculated as the difference between ration supplied and remaining. Every 18 d lambs were individually weighed for average daily gain (ADG) calculation. Data were analyzed using the PROC MIXED with SPS, BO, GC and their interactions were considered as fixed effects. Animal (SPS×BO×GC) was considered as random effect. Treatments were considered different when P≤0.05. Daily ration intake (DRI) was lower in diet C+PG+PP compared to C+PG (P=0.05, 0.754 vs. 0.800 kg/d), and in pastures with black oat oversowing drilled compared to broadcast (P=0.03, 0.751 vs. 0.803 kg/d), in the first growing season. In first GC of first and second growing seasons, the DRI was lower than second GC [(P<0.001, 0.547 vs. 1.007 kg/d and P<0.001, 1.76 vs. 2.51% BW) and (P<0.001, 0.559 vs. 1.283 kg/d and P<0.001, 1.98 vs. 3.45% BW)], respectively. The ADG was lower in the first GC than second GC (P=0.005, 0.222 vs. 0.264 kg/d), in the first growing season. This difference was due to the greater forage availability in the first GC reducing the DRI. Consequently, the greatest DRI resulted in increased ADG in the second GC. In conclusion, corn silage intercropped with palisade grass and pigeonpea did not affect performance of semi-feedlot lambs, being a strategy in integrated crop-livestock system.