new research debunks trad views on nutrition

[saysfaa]

... Now I'm wondering where I get my selenium, other than my One-A-Day. I don't eat fish, almost ever.

One brazil nut has the right amount of selenium for a person for a day. Not so much that you need to worry about getting some in the other foods you eat but enough to not have to worry about getting enough in your diet.

 

[Perris]

a tin of sardines is also a cheap and easy source of multiple minerals, including selenium.

 

[Perris]

on selenium deficiency, Merck writes
"
A deficiency of selenium in growing chickens causes exudative diathesis. Early signs of unthriftiness and ruffled feathers usually occur at 3–6 weeks of age, depending on the degree of deficiency. The edema results in weeping of the skin, which is often seen on the inner surface of the thighs and wings. The birds bruise easily, and large scabs often form on old bruises. In laying hens, such tissue damage is unusual, but egg production, hatchability, and feed conversion are adversely affected.

The metabolism of selenium is closely linked to that of vitamin E, and signs of deficiency can sometimes be treated with either the mineral or the vitamin. Vitamin E can spare selenium in its role as an antioxidant, and so some selenium-responsive conditions can also be treated by supplemental vitamin E. In most countries, there are limits to the quantity of selenium that can be added to a diet; the upper limit is usually 0.3 ppm because of the potential for toxicity at relatively low levels.

The commonly used forms of selenium are sodium selenite and, more recently, organic selenium chelates. Feeds grown on high-selenium soils are sometimes necessarily used in poultry rations and are good sources of selenium. Fish meal and dried brewer’s yeast are also rich in available selenium."

I maintain that these are not symptoms that a chicken can hide, and there is no suggestion that a deficiency kills quickly. It is also stated that selenium deficiencies can sometimes be treated, and that excess selenium is potentially toxic. Giving a 'balancer' is a blanket administration of all the minerals in it, which may take it to toxic levels for some of them if the bird is already getting ample in their regular diet.

 

[U_Stormcrow]

Selenium addition to chicken feed here in the US is limited to 30 micrograms per kilogram. Toxic levels of selenium in chickens are about 1 to 10 parts per million. A microgram per kilogram is one part per billion. That's billion with a b. 1 1,000 of a part per million. I contend that there is a reasonable safety factor between 30 parts per billion and conservatively one part per million.

 

[Perris]

but accidents/mistakes happen
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3225252/

edited to add a line from the intro to that paper: "The amount of selenium available in a diverse diet with meat, grains, vegetables, and nuts is typically sufficient to negate the necessity for supplementation"

 

[U_Stormcrow]

Of course they do, but the chances of that accident occurring to me are less than the chances of my being struck by lightning on a clear blue day. On the other hand the chances of my soils being selenium deficient are 100%. Simple risk management. If I lived my life in the fear of human mistakes, knowing that they are sometimes fatal, I would not be driving my Buick towing a trailer that I built myself behind it with a bunch of parts I bought off the shelf, while speaking on my cell phone and listening to the radio. At some point you have to roll your dice and take your chances.

 

[Perris]

It seems to me that trusting a chicken's instincts to know what to eat, and how much of it to eat, is a less risky strategy. We can help by providing them with a diverse range of foods in a recognizable and minimally processed form, and letting them select what they want to eat. Perhaps the most difficult step is letting go of control over them and their diets.

 

[U_Stormcrow]

I free range - as you know. But I know my soils are deficient across a range of measures, as are the crops I can successfully grow. So I provide commercial feed and let them suppliment/balance down with what they obtain in the pasture and the surrounding wood.

No matter how enticing it may be to simply trust, they can't eat what isn't present.

Different situations, different needs, different management.

 

[saysfaa]

.... In laying hens, such tissue damage is unusual....

Presumable at the same level of deficiency that caused the visible signs in young chicks.

...there is no suggestion that a deficiency kills quickly..

In and of itself, probably not. But when the immune system is challenged then even differences much too small to be seen in feathering or scab size can affect the mortality rate from fast acting pathogens. Bolding in the following is mine.

Section 3.1
"...Positive effects of selenium supplementations in amounts exceeding the nutritional requirements have been observed for coccidiosis, necrotic enteritis and avian pathogenic E. coli (APEC) in poultry, where supplemental selenium seems to increase disease resistance and/or alleviates symptoms associated with the disease (Larsen et al., 1997; Mahmoud and Edens, 2005; Wunderlich et al., 2014; Lee et al., 2014a; Lee et al., 2014b; Xu et al., 2015)....The tendency to more extensive rearing systems with access to outdoor areas (free range and organic production) has contributed to increasing problems with E.coli infections in poultry production (Guabiraba and Schouler, 2015). Larsen et al. (1997) found that an inorganic selenium source added at a dietary supplemental dose of 0.4 mg/kg (total selenium content of 0.45 mg/kg feed) reduced bird mortality and air sac lesions, when white leghorn type chickens were inoculated with E. coli (serotype O1:K1) in the lower abdominal air sac...."

source of quote in picture

 

[saysfaa]

The other side to such things as were my last few post is how many factors influence any given thing. Like the Vitamin E decreasing the amount of selenium needed. Like Vitamin K having a role in Vitamin D enabling Calcium to be absorbed - and fat in the diet being necessary for both Vitamin D and Vitamin K to function. Or excess salt in the diet resulting in Calcium being pulled from the bones (I'm drowning a bit in calcium related things as I recently found out I have osteoporosis quite a bit worse than "normal" - if there is such a thing.)