# Encapsulated Butyric Acid and Zinc as a Feed Additive for Lambs Abruptly Transitioned to a Grain-Based Diet

## TL;DR

This study tested if encapsulated butyric acid and zinc could help lambs adjust to a sudden switch to a grain-based diet, but found no significant benefits for growth or gut health.

## Contribution

The study evaluates the efficacy of encapsulated butyric acid and zinc in lambs during abrupt diet transitions, providing new insights into feed additive effectiveness.

## Key findings

- BZ supplementation did not improve growth performance or carcass traits in lambs.
- BZ had no positive effects on rumen or small intestine measurements.
- BZ increased body wall thickness but decreased red meat yield and retail cuts.

## Abstract

During diet transition periods, ruminal acidosis can have negative effects on gut health and performance of ruminants and investigating feed additives that may help alleviate some of these negative effects is critical. Butyric acid and zinc have been studied as feed additives that can improve gastrointestinal health in ruminants and may be suitable to help decrease negative effects of ruminal acidosis. Thus, a study was conducted to evaluate if a partially encapsulated butyric acid and zinc feed additive was effective at improving growth performance, carcass characteristics, and gastrointestinal health in feedlot lambs abruptly transitioned to a 100% concentrate diet.

Butyric acid is attributed to gastrointestinal epithelial development and health and two studies were conducted to determine if supplementing encapsulated butyric acid and zinc (BZ) in lambs abruptly transitioned to a finishing diet has effects on growth performance, efficiency of dietary net energy utilization, rumen morphometrics, small intestinal histology, and carcass traits. Polypay wethers (n = 84; initial shrunk body weight = 38.8 kg ± 4.8 kg) were used in a randomized complete block design study. Wethers were abruptly transitioned from a high roughage-based diet to a 100% concentrate-based diet and dietary treatments were 0 or 2 g BZ/kg of diet dry matter. Study 1 evaluated growth performance and carcass traits of lambs over a 59.5 d feeding period, and Study 2 evaluated changes in rumen morphometrics and small intestine histology in serial harvested lambs. Wethers supplemented with BZ had increased body wall thickness, decreased calculated boneless closely trimmed retail cuts, and decreased red meat yield (p ≤ 0.03) compared to non-supplemented wethers. Linear effects (p ≤ 0.01) for harvest date were observed for most rumen and small intestine measurements. Supplementing wethers with BZ did not improve growth performance, carcass traits, or rumen and small intestine measurements. The effects of BZ supplementation on fat deposition in ruminants should be further investigated.