PSX-25 Narasin inclusion and levels of forage on performance of feedlot lambs

Abstract The objective of this study was to determinate the effects of forage levels and narasin inclusion on the performance of feedlot lambs. Forty-four lambs were allotted in a randomized complete block design, defined by initial body weight (BW), in a 2x2 factorial arrangement. The first factor was forage (coastcross hay) inclusion (10 or 20%, DM basis) and the second factor was narasin (0 or 13 ppm). The experimental diets were isonitrogenous (17.4%, DM basis). The experiment lasted 112 days, divided into two periods of 56 d each. The lambs were weighed after a fasting period of 14 hours on days 0, 56, and 112. Average daily gain (ADG), dry matter intake (DMI) and feed efficiency (FE) were determined in each period. Data were analyzed as repeated measures over time using the MIXED procedure of SAS and the LSMEANS option was used to obtain the means. The effects were considered significant when P < 0.05. There was no interaction between forage levels and narasin inclusion. Narasin did not affect the DMI, ADG, and FE. There was hay levels and period interaction for DMI and ADG. Increase levels of hay did not affect the DMI during the first period; however, 20% of hay inclusion increased DMI in the second period (1.16 vs 1.30 kg/d; P = 0.01). The inclusion of 10% of hay increased the ADG in the first period (0.28 vs 0.24 kg/d; P < 0.01), however, there was no effect in the second period. Consequently, 10% of forage inclusion increased the FE (0.23 vs 0.21; P = 0.01). In summary, diets containing 10% of forage improves the FE, and narasin inclusion did not affect the lamb’s performance.