Whole corn grain in diets without roughage or associated with increasing levels of roughage for feedlot lambs: ingestive behavior

Abstract

The objective of this experiment will be to evaluate the effect of feeding diets based on whole corn grain without forage or associated with increasing levels of roughage on the ingestive behavior of feedlot lambs. Forty five young lambs, Dorper x Santa Inês crossbred, uncastrated and with an initial body weight of approximately 18.0 kg and 60 days of age, will be assigned to a randomized complete block design (9 blocks and 5 treatments). The experimental treatments were defined by the addition of increasing levels of roughage in association with whole corn grain in high-concentrate diets for lambs, as follows: MI + 0R - diet based in whole corn grain without roughage; MI + 5R - diet based in whole corn grain + 5% roughage; MI + 10R - diet based in whole corn grain + 10% roughage; MI + 15R- diet based in whole corn grain + 15% roughage; Control (CONT) - Diet based on ground corn grain containing 10% of roughage. Daily, all rations will be weighed in an electronic scale with 1 g of precision (Marte®, LC 100, São Paulo, Brazil) and offered. Eating behavior observations for each animal (n = 45) will be visually recorded every 5 min for 24 hours on days 28, 56 and 84 of the feeding trial. Two properly trained observers will be used for each 3 hour interval. Eating, ruminanting, total chewing and drinking time will be expressed as minutes per day. Time (expressed in minutes) expended in each activity will be calculated by the number of observations recorded multiplied by 5. Total chewing time will be considered the sum of eating and ruminanting times. Eating, ruminanting, and total chewing times will be also expressed as minutes per gram of DMI and NDF intake. All data will be analyzed using the MIXED procedure of SAS (1999).