Preliminary study: From biofortified maize to cow milk enriched with selenium: An on-farm strategy using selenium-enriched silage

Selenium (Se) supplementation isacommon practice indairy nutrition. However, the use ofbiofortified feedstuffs remains anot fully realized strategy toenhance the Se content ofanimal derived products. This study explored anon-farm biofortification approach byincorporating Se-enriched maize silage into the total mixed ration (TMR) ofdairy cows. Sixty Holstein cows were divided into acontrol group (CON), receiving aconventional diet with selenite supplementation (0.6mg/kg Se inTMR), and anexperimental group (EXP), inwhich conventional silage was replaced with high-Se silage (0.9mg/kg Se inTMR). The trial lasted 22weeks, including one week ofadaptation and four weeks after supplementation, when Se concentrations inmilk, Se transfer efficiency, and key milk components critical for the production ofSe-enriched dairy products were assessed. The higher Seconcentration inthe TMR had noadverse effects onmilk composition orantioxidant status. Milk Se concentration inthe EXP group increased rapidly, reaching 68µg/l within two weeks, significantly higher (P<0.005) thaninthe CONgroup (27µg/l). Se transfer efficiency to milk was also higher in the EXP group (13.9%) compared to the CON group (8.8%). The diverse Se species in biofortified silage, confirmed through the speciation analysis, may have contributed to these outcomes. However, the gradual decline in milk Se after the initial peak warrants further investigation into physiological factors or changes in silage Se speciation during storage.