Effect of Feeding Selenium-Fertilized Alfalfa Hay on Performance of Weaned Beef Calves

Jean A Hall,Janice K Hunter,Whitney C Stewart,Wayne D Mosher,Jorge A Vanegas,Charles T Estill,Gene J Pirelli,Gerd Bobe,William R Vorachek,Pascale Chavatte-Palmer

doi:10.1371/journal.pone.0058188

Abstract

Selenium (Se) is an essential micronutrient in cattle, and Se-deficiency can affect morbidity and mortality. Calves may have greater Se requirements during periods of stress, such as during the transitional period between weaning and movement to a feedlot. Previously, we showed that feeding Se-fertilized forage increases whole-blood (WB) Se concentrations in mature beef cows. Our current objective was to test whether feeding Se-fertilized forage increases WB-Se concentrations and performance in weaned beef calves. Recently weaned beef calves (n = 60) were blocked by body weight, randomly assigned to 4 groups, and fed an alfalfa hay based diet for 7 wk, which was harvested from fields fertilized with sodium-selenate at a rate of 0, 22.5, 45.0, or 89.9 g Se/ha. Blood samples were collected weekly and analyzed for WB-Se concentrations. Body weight and health status of calves were monitored during the 7-wk feeding trial. Increasing application rates of Se fertilizer resulted in increased alfalfa hay Se content for that cutting of alfalfa (0.07, 0.95, 1.55, 3.26 mg Se/kg dry matter for Se application rates of 0, 22.5, 45.0, or 89.9 g Se/ha, respectively). Feeding Se-fertilized alfalfa hay during the 7-wk preconditioning period increased WB-Se concentrations (P Linear<0.001) and body weights (P Linear = 0.002) depending upon the Se-application rate. Based upon our results we suggest that soil-Se fertilization is a potential management tool to improve Se-status and performance in weaned calves in areas with low soil-Se concentrations.

Highlights

Selenium (Se) is an essential micronutrient of cattle
Fertilizing fields with increasing amounts of sodium-selenate increased in a dose-dependent manner the Se-content of secondcutting alfalfa hay from 0.07 to 0.95, 1.55, and 3.26 mg Se/kg dry matter for sodium-selenate application rates of 0, 22.5, 45.0, or 89.9 g Se/ha, respectively (Figure 1)
Based on the total amount of alfalfa hay and grain concentrate fed to each group of calves, average dry matter intake per head was calculated at 5.59 kg/head/d for alfalfa hay starting on day 12, and 0.20 kg/head/d for grain concentrate for the first 5 wk and 0.40 kg/head/d for the last 2 wk

Summary

Introduction

Selenium (Se) is an essential micronutrient of cattle. Provision of adequate Se is important to prevent Se-responsive diseases in growing cattle such as nutritional myodegeneration and Seresponsive unthriftiness [1]. Many parts of the world, including Oregon, USA, are known to have soil conditions conducive to deficient forage-Se content, potentially leading to clinical signs of Se deficiency in livestock grazing or fed crops raised on them [2]. Soils are the major source of Se for plants and soil-Se exits in various forms including selenides, elemental Se, selenites, selenates and organic Se compounds [3]. Low soil pH and high concentrations of sulfur and phosphorus from fertilization decrease Se availability for plants. Leaching from the topsoil in areas of high rainfall or irrigation lowers forage-Se content.

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