Effect of starch and physically effective neutral detergent fiber inclusion on dry matter intake variation and ruminal motility of feedlot cattle

Abstract

Roughage should be included at reduced levels in high-concentrate diets due to lower nutritional composition, higher operating costs and to maximize energy intake during the feedlot period. Therefore, optimizing roughage levels in high-concentrate diets is necessary to improve animal performance. Thus, this study aimed to test the effect of starch and physically effective neutral detergent fiber (peNDF) inclusion on dry matter intake (DMI) variation and ruminal motility of feedlot cattle. Eight Nellore yearling bulls (350 kg), previously fit with a cannula, will be housed in individual pens. The study will be conducted as a 4 × 4 Latin squares balanced for carry-over effects with 2 × 2 factorial arrangement of treatments, with the following factors: peNDF inclusion (low vs. high peNDF) and starch inclusion (22.5% vs. 45% of dry matter (DM) of the diet). Step-up protocol will be used as the adaptation protocol, where 72% and 79% of concentrate diets will be fed for 7 days each, totalizing 14 days. Each period of the Latin square consisted of 21 days including 14 days without sampling and 7 days of sampling. The study will last 98 days. The DMI variation will be calculated as the difference in DMI between two consecutive days, determined in percentage and kilogram. Ruminal motility will be measured for 6 hours, starting at 10:00 am and ending at 4:00 pm on day 16 of each experimental period. Will be evaluated as response variables: DMI variation and ruminal motility.