Effect of Supplemental Selenomethionine on Growth Performance and Serum Antioxidant Status in Taihang Black Goats (Report‪)‬

INTRODUCTION Selenium (Se) is an essential trace element for maintaining normal physiological processes in animals and humans. Se exerts multiple actions on the antioxidant (Arthur, 2000; Tapiero et al., 2003), reproductive (Maiorino et al., 1999), endocrine (Beckett and Arthur, 2005), and immune systems (McKenzie et al., 1998; Beck et al., 2005). It exists in nature in organic and inorganic forms. The main Se supplement that has been used in animal diets is the inorganic form (sodium selenite or selenate). However, absorption of inorganic selenium is much lower in ruminants than in non-ruminants. Wright and Bell (1966) reported that absorption of orally administrated [sup.75]Se was only 34% in sheep compared with 85% in swine, which is due to reduction of selenate and selenite to insoluble selenide and elemental Se in the rumen environment (Hidiroglou et al., 1968). Some studies indicated that organic selenium from selenomethionine (Se-Met) or Se-enriched yeast is an ideal additive because animals absorb and retain it more than inorganic selenium (Ortman and Pehrson, 1997). Organic Se supplementation did not affect growth performance but increased serum and tissue Se concentration in growing-finishing pigs (Tian et al, 2006a, b) and in broilers (Choct and Nylor, 2004; Payne and Southern, 2005; Yoon et al., 2007). Ehlig et al. (1967) found higher tissue selenium retention by lambs fed selenomethionine than fed selenite, which results from incorporation of part of selenomethionine into microbial protein by rumen microorganisms (Paulson et al., 1968; Hidiroglou et al., 1973). Recent studies by Juniper et al. (2006; 2008) and Steen et al. (2008) have indicated improved bioavailability of Se when using organic selenium. The tolerance of ruminant animals (dairy cattle, beef cattle, calves and lambs) to a high dose of a selenium-enriched yeast was at least 20 times the maximum permitted within the United States (0.30 mg/kg of DM) (Juniper et al., 2008).