PSIV-17 - Supplementing Gentamicin Sulfate Through the Water Impacts the Performance Response of Nursery Pigs to Structural Fiber

Abstract: Dietary fiber has varying effects on nursery pig performance, which is a period when medications are supplemented to support disease challenges. An experiment was conducted to determine the effects of gentamicin sulfate (GS) water medication, dietary structural fiber, and their interaction on growth performance of nursery pigs. In total, 900 weanling pigs (initial body weight = 5.71 ± 0.04 kg) were randomly allotted to a 2 × 2 factorial arrangement of treatments (10 pens/treatment, 22 pigs/pen). Dietary treatments consisted of nursery diets with no additional fiber (CON) or nursery diets with 8% wheat middlings (STR) as a source of structural fiber. Phase 1 and 2 diets were fed from day 0-12 and day 12-21, respectively. Water medication treatments consisted of no GS or GS delivered through the drinking water from day 0-7 post-weaning (5 g GS per gallon stock solution at a 1:126 dilution of stock solution to drinking water). Data were analyzed using a general linear model in R. Contrasts tested the main effects of structural fiber, GS supplementation, and their interaction. Phase 1 average daily gain (ADG) and average daily feed intake (ADFI) did not differ, but gain:feed (G:F) was greater (P < 0.05) with GS (Table 1). Interactions (P < 0.05) were observed for day 21 body weight, ADG, and ADFI in phase 2, where additional structural fiber increased performance variables in absence of, but not in conjunction with, GS supplementation. A tendency for an interaction (P < 0.10) was observed for phase 2 G:F, where additional structural fiber increased G:F when no GS was administered but reduced G:F when GS was supplemented. In conclusion, the use of water medication impacted the performance response to dietary structural fiber, as pigs responded beneficially to additional fiber when GS was not administered, potentially due to modifications to the microbiome.