A study by researchers at the University of Reading and nutrition company Adisseo has shown dietary selenium supplementation of cows before calving can enhance their and their calves' selenium status. The study also showed organic forms of selenium were more effective than inorganic forms.
Results of the research were presented at the Australasian Dairy Science Symposium.
Selenium is an essential trace element in livestock for antioxidant, immune and reproductive functions.
Selenium deficiency can impair reproduction, development and production of dairy cows due to uncontrolled oxidative stress.
There is a positive correlation between the selenium status of a cow at calving and its offspring.
Previous research has shown that the selenium status of calves born from cows fed on diets supplemented with selenium during late gestation is better maintained in the early post-calving period than that of calves receiving injectable sources of selenium.
The researchers said this had meant that dietary selenium supplementation was practised widely, either in an inorganic form of selenium such as sodium selenite or in an organic form such as selenium yeasts.
Previous research in Belgian Blue beef cows had shown organic forms of selenium fed in late gestation further improved the selenium status of calves compared with mineral forms of selenium.
This latest research looked at a new molecule, hydroxy-selenomethionine, which has been introduced as a pure form of organic selenium supplement. The study aimed at comparing its efficacy with that of selenite when offered to heifers during late gestation.The results showed that dietary supplementation with selenium to the heifers significantly increased selenium levels in their blood plasma, both just before and after calving.
It also lifted the selenium levels in the cows' colostrum and in their calves' blood plasma.
The study show heifers receiving the organic form of selenium had higher levels of selenium in their blood plasma and colostrum than those receiving the inorganic form.
This is attributable to the better bioavailability of organic selenium and the incorporation of selenomethionine, which is one of the amino acids called containing the selenium in the organic form.
The blood plasma levels were also higher in the calves of the cows receiving the organic form. This was attributed to the more efficient transfer of selenomethionine through the placenta.
The study used 42 in-calf Holstein-Friesian heifers that were randomly assigned to three groups: one receiving a diet with no selenium, one receive a diet with 0.3 milligrams per kilogram of dry matter of mineral selenium as selenite and one received 0.3mg/kg DM of organic selenium as hydroxy-selenomethionine.
All heifers were fed a diet with no supplementation for a seven-week washout phase, followed by an eight-week supplemental phase.
Blood samples were taken from each animal at the start of the study, at the end of the wash-out phase, two-weeks pre-calving and immediately after calving. Blood samples were also taken from new-born calves. Colostrum was also taken as close to calving as possible.
The study Hydroxy-selenomethionine is an Effective Selenium Source for Pregnant Heifers was undertaken by D. T. Juniper, C. Rymer from the School of Agriculture, Policy and Development at the University of Reading, Reading, M. Briens and M. De Marco from Adisseo France and Y. G. Liu from Adisseo Asia Pacific.
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