Suckler selenium status improved through enriched fertiliser use
Take Home Message: The use of selenium enriched fertilisers on deficient pastures will improve the selenium status of suckler cows during the summer and winter and avoids the requirement for dietary supplementation.
The use of selenium-enriched fertilisers can improve and maintain a high selenium (Se) status in beef herds managed over several years on locally produced feedstuffs during successive outdoors and indoors seasons. That was the conclusion of a five-year study carried out by scientists in Belgium and Norway, the result of which were presented to delegates at this year’s British Society of Animal Science’s annual conference.
Antioxidant mechanisms, immune responses, reproduction and thyroid metabolism are all processes in which the trace element selenium (Se) is involved. In suckling herds, a Se deficiency could impair animal health and result in reduced productivity.
In Belgium the Se content in locally produced feedstuffs is low and in beef herds where locally produced feedstuffs are fed for the entire year, symptoms of Se deficiency are often observed. So the aim of the study was to assess the effect of Se enriched fertilisers on the Se content of feedstuffs and on the Se status of cattle.
The Experimental Research Station of the Veterinary Faculty of the University of Liege began using Se enriched fertilisers in 2002. For the grazing pastures, 3g of Se/ha was applied at each nitrogen application. For pastures used for grass silage, 3g of Se/ha was applied at the beginning of the season and then again after each cut. And 4g of Se/ha were spread at the second and third nitrogen applications for barley production. For maize from year three, 8g of Se/ha was applied at sowing. And there were control pastures – fields with no Se application but similar management.
The faculty’s Belgium Blue suckler herd was split in two at the beginning of the trial with 18 cows in each group. Cows, calves and young stock remained in their respective group throughout the experiment. During the grazing period, animals had only access to grazed pastures. During the winter period, the ration was made of grass silage, maize silage and barley produced with or without Se enriched fertilisers, as appropriate to treatment group, and supplemented with dehydrated lucerne, sugar beet pulp and bran.
And the trial found that the average dietary Se was 54, 247 and 138 μg/kgDM in the control group and in the Se groups during summer and winter respectively. At the beginning of the trial, plasma Se concentration was low for both groups. And it remained low during the five-year trial in the control group.
By contrast, the plasma Se content was increased in the Se group by the end of the first winter period. And a further increase was observed during the grazing season. The following winter was characterised by slightly lower concentrations. Similar patterns were observed during the following grazing and winter periods.
The Se content in the red blood cells followed a similar pattern to that observed for plasma. The reduced concentrations during the winter periods as compared to grazing periods were due to reduced Se intake associated with the purchased feedstuffs offered during the indoors period.
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