Abstract:
Selenium is an essential nutrient in both human and animal nutrition and plays an important role in the immune function within cells. Humans and animals obtain selenium nutritionally and the amount is directly related to the selenium content of the food that is eaten. The most effective and responsible way to increase the selenium status of the population is through selenium-enriched foodstuffs, particularly protein-rich food sources such as eggs. Selenium sources differ in their bioavailability to the bird and the amount of selenium deposited into the egg by the hen is directly related, not only to the amount of selenium added to the feed, but the relative bioavailability of the selenium to the bird. Four treatments were formulated, each using a different source of selenium available for use in feeds. The treatments consisted of three organic selenium sources and one inorganic source, namely; selenoyeast (Sel-Plex manufactured by Alltech), hydroxymethylselenobutanate (Selisseo produced by Adisseo), selenium proteinate (B-Traxim from Pancosma) and the inorganic source, sodium selenite (manufactured by Protea). The treatments all used a basal layer mash devoid of any added selenium and selenium was supplemented as follows; 1.2 mg/kg sodium selenite (SS), 1.2 mg/kg selenoyeast (SY), 1.2 mg/kg hydroxymethylselenobutanate (HMSeBA) and 1.2 mg/kg selenium proteinate. One hundred and sixty (160) 42-week old Amberlink hens were randomly assigned so that there were forty hens per treatment. Each hen was caged individually with ad libitum access to water and 160 g/day of assigned treatment feed. Eggs were collected daily to record egg production and egg yolk, albumen and shell weights for each treatment were recorded weekly for 21 days. Eggs collected from each treatment were stored either at room temperature or in a fridge for 28 days and yolk pH, albumen pH and albumen height were recorded every seven days. Selenium source had no effect on egg production or the weight of egg shell, albumen or yolk. Selenium concentration in the egg was significantly higher for eggs from the HMSeBA treatment and lowest in the SS treatment. Eggs stored at room temperature had significantly lower egg quality than eggs stored in the fridge, as indicated by lower albumen heights, higher albumen and yolk pH values and lower Haugh Unit scores. Selenium source did not have a significant effect on egg quality for either storage temperature.
