Effects of different feeding frequencies on DMI variation and selective consumption by feedlot cattle
This study, conducted at the São Paulo State University feedlot, Dracena Campus, Brazil, was designed to determine the effects of different feeding frequencies on DMI variation and selective consumption (sorting) of diets by Nellore cattle. The experiment was designed as a completely randomized block, replicated 12 times, in which 48 18-mo-old yearling Nellore bulls (358.2±19.4 kg) were fed in individual pens for 94-d according to the following treatments: 1) feeding one time daily (1x; 0800), 2) feeding two times daily (2x; 0800 and 1400), 3) feeding three times daily (3x; 0800, 1100 and 1400), and 4) feeding four times daily (4x; 0800, 1100, 1400 and 1700). The adaptation program consisted of ad libitum feeding of two adaptation diets over period of 14-d with concentrate level increasing from 60% to 86% of diet DM. The finishing diet contained: 67.0% cracked corn grain, 14.0% sugarcane bagasse, 9.0% soybean hulls, 5.5% soybean meal, 4.0% supplement containing 30% of urea, and 0.5% limestone (DM basis). The DMI variation was calculated for each individual yearling bull as the difference in intake, expressed as % of variation, between consecutive days throughout the study. Samples of orts and diets were collected on days 12 and 51 of the study for particle size distribution determination, which was performed by sieving using the Penn State Particle Size Separator and reported on as-fed basis. Values equal to 1.0 indicate no sorting, <1.0 show selective refusals, and >1.0 indicate preferential consumption. Orthogonal contrasts were used to assess linear, quadratic, and cubic relationship between feeding frequency and the dependent variable. During the period of adaptation, DMI variation was affected (P < 0.01) cubically as feeding frequency increased (1x = 16.1%; 2x = 23.2%; 3x = 14.4%; 4x = 15.9%), however, feeding frequency did not affect (P > 0.10) DMI variation during the finishing period. Feeding frequency only affected particle sorting during the adaptation period, in which as feeding frequency increased, sorting for screen 3 (diagonal opening = 1.18 mm) was affected (P < 0.01) quadratically (1x = 0.993; 2x = 0.995; 3x = 0.999; 4x = 0.985). Thus, based on the results of this study, feeding frequency affects DMI variation and diet sorting only during the adaptation period. Cattle fed three times daily presented lower DMI variation and lesser extent of sorting.
Keywords: fluctuation, Nellore, sorting