EFFECT OF STARCH AND PHYSICALLY EFFECTIVE NEUTRAL DETERGENT FIBER INCLUSION ON RUMINAL POOL SIZE AND NEUTRAL DETERGENT FIBER TURNOVER IN CATTLE FED HIGH ENERGY DIETS

Abstract

The lower fiber inclusion in finishing diets may increase the risk of nutritional disorders such as ruminal acidosis, negatively impacting health, and consequently growth performance of feedlot cattle. 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. The reticulo-ruminal contents will be completely evacuated 3 h after feeding (12:00 h) on day 21 and 3 h before feeding (06:00 h) on day 1 of each experimental period. Will be evaluated as response variables: pool size and ruminal turnover.