Clinical Biochemistry of Domestic Animals

Selenium-enriched yeast (Se-yeast) is a common form of Se used to supplement the dietary intake of this important trace mineral. However, its availability within the European Union is under threat, owing to concerns expressed by the European Community (EC) Scientific Committee on Food that Se-yeast supplements are poorly characterised and could potentially cause the build up of Se in tissues to toxic levels. The present review examines the validity of these concerns. Diagrams of the biosynthesis and metabolism of Se compounds show which species can be expected to occur in Se-yeast preparations. Se-yeast manufacture is described together with quality-control measures applied by reputable manufacturers. The way in which speciation of Se-yeast is achieved is explained and results on amounts of Se species in various commercial products are tabulated. In all cases described, selenomethionine is the largest single species, accounting for 54-74 % of total Se. Se-yeast is capable of increasing the activity of the selenoenzymes and its bioavailability has been found to be higher than that of inorganic Se sources in all but one study. Intervention studies with Se-yeast have shown the benefit of this form in cancer prevention, on the immune response and on HIV infection. Of about one dozen supplementation studies, none has shown evidence of toxicity even up to an intake level of 800 microg Se/d over a period of years. It is concluded that Se-yeast from reputable manufacturers is adequately characterised, of reproducible quality, and that there is no evidence of toxicity even at levels far above the EC tolerable upper intake level of 300 microg/d.

/pdf/the-use-of-high-selenium-yeast-to-raise-selenium-status-how-30ucarx3jw.pdf

The use of high-selenium yeast to raise selenium status: how does it measure up?

http://ssu.ac.ir/cms/fileadmin/user_upload/Mtahghighat/tfood/ARTICLES/meat/Improving_functional_value_of_meat_products.pdf

Improving functional value of meat products.

Background
This review is an update of the first Cochrane publication on selenium for preventing cancer (Dennert 2011).

Selenium is a metalloid with both nutritional and toxicological properties. Higher selenium exposure and selenium supplements have been suggested to protect against several types of cancers.

Selenium for preventing cancer

Publisher Summary This chapter discusses the nutritional significance, metabolism, and toxicology of selenomethionine (SeMet). SeMet is a naturally occurring toxic amino acid, but at the same time represents the major nutritional source of selenium for higher animals and humans. The ability of SeMet to be incorporated into the body proteins in place of Met furthermore provides a means of reversible Se storage in organs and tissues. This property is not shared by any other naturally occurring selenoamino acid, and thus could be associated with a specific physiological function of SeMet. Because higher animals cannot synthesize SeMet, yet all needed forms of selenium (Se-) are produced from it; SeMet meets the criteria of an essential amino acid. Accordingly, SeMet, or enriched food sources thereof, are appropriate forms of Se for human nutritional Se supplementation. However, while SeMet or Se yeast are already widely used in over-the-counter nutritional supplements, infant formulas and parenteral feeding mixtures still contain Se in the form of sodium selenate or sodium selenite, even though these are not the normal nutritional forms of Se. In animal nutrition, these inorganic selenium salts are increasingly replaced by food sources of SeMet, such as Se yeast. Synthetic SeMet could also be employed as a feed additive, but its regulatory status is yet undetermined.

The nutritional significance, metabolism and toxicology of selenomethionine.

This experiment evaluated the effect of high dietary Se levels using organic or inorganic Se on the selenosis responses in growing-finishing swine. A 2 x 4 factorial arrangement of treatments in a randomized complete block design was conducted in two replicates. Sodium selenite or Se-enriched yeast was added at 5, 10, 15, or 20 ppm Se to corn-soybean meal diets. A basal diet without added Se was a ninth treatment group. Ninety crossbred barrows initially averaging 24.7 kg BW were allotted at five pigs per pen. Pigs were bled at 3-wk intervals and plasma Se, glutathione peroxidase (GSH-Px) activity, glutamic oxalacetic transaminase (PGOT), hemoglobin, packed cell volume, and blood cell Se concentration were measured. After 12 wk, pigs were killed and various tissues and bile were collected for Se analyses. Pig body weights, daily gains, and feed intakes were similar for both Se sources when provided at or = 10 ppm inorganic Se but at > or = 15 ppm organic Se level. Plasma GSH-Px activity increased (P or = 15 ppm Se but not when organic Se was fed, resulting in an interaction (P 10 ppm inorganic Se and at 20 ppm when organic Se was provided. Bile Se increased as dietary Se level increased (P or = 5 ppm Se, but subsequent selenosis effects were more severe and occurred sooner when sodium selenite was the Se source.

Comparative effects of high dietary levels of organic and inorganic selenium on selenium toxicity of growing-finishing pigs.

A 2 x 2 factorial arrangement of treatments in a randomized complete block design was conducted at two time periods using a total of 43 first-parity gilts. Two sources of Se (selenite or Se-enriched yeast) were added at .1 or .3 ppm to corn-soybean meal diets to evaluate reproductive performance and gilt and progeny tissue Se contents. Treatment diets were initially provided approximately 60 d before breeding. Gilts were bled at periodic intervals and serum glutathione peroxidase (GSH-Px) activity and Se concentrations were determined. Milk was collected at parturition and at weekly intervals to weaning (21 d) for Se analysis. Liver and loin tissues were collected from stillborn (n = 17) and neonatal pigs (n = 19) before colostrum consumption. Three pigs from each litter were bled at weaning, and six pigs per treatment group were killed (two/litter) and tissue (liver, loin, kidney) collected. Three to four sows per treatment were killed at weaning and tissue (loin, liver, pancreas, kidney) collected. Tissues collected from each were analyzed for Se. Dietary Se level or Se source had no effect (P > .15) on gilt reproductive performance. Gilt serum GSH-Px activity was generally similar at the .1 and .3 ppm Se level for either Se source, whereas serum Se was consistently higher when the dietary Se level was .3 ppm. Colostrum Se content was unaffected by Se source and Se level, but milk Se increased as the dietary Se level increased and when the Se-enriched yeast source was fed, resulting in an interaction response (P < .01). Loin tissue had similar Se contents between stillborn and neonatal pigs. Loin Se content was higher when dietary Se level increased (P < .05) and when the Se-enriched yeast source (P < .01) was fed to gestating gilts. Weanling pig lion Se content increased as dietary Se level increased (P < .01) and when the Se-enriched yeast source was fed (P < .01). A higher liver Se content in weaned pigs also resulted when the dietary Se level was .3 ppm (P < .08) and when the Se-yeast (P < .01) was provided. Weanling pig serum GSH-Px activity was similar regardless of the Se level or Se source fed to the dam, but serum Se increased when the .3 ppm Se level and the Se-yeast was fed to the gilt. If GSH-Px activity is used as the criterion to evaluate Se adequacy, then .1 ppm Se from either Se source was adequate, but if higher milk Se or pig tissue content is desired, then a .3 ppm Se level from the Se-enriched yeast source was superior to inorganic Se.

Effect of inorganic or organic selenium at two dietary levels on reproductive performance and tissue selenium concentrations in first-parity gilts and their progeny

Dietary acidifiers appear to be a possible alternative to feed antibiotics in order to improve performance of weaning pigs. It is generally known that dietary acidifiers lower gastric pH, resulting in increased activity of proteolytic enzymes, improved protein digestibility and inhibiting the proliferation of pathogenic bacteria in GI tract. It is also hypothesized that acidifiers could be related to reduction of gastric emptying rate, energy source in intestine, chelation of minerals, stimulation of digestive enzymes and intermediate metabolism. However, the exact mode of action still remains questionable. Organic acidifiers have been widely used for weaning pigs' diets for decades and most common organic acidifiers contain fumaric, citric, formic and/or lactic acid. Many researchers have observed that dietary acidifier supplementation improved growth performance and health status in weaning pigs. Recently inorganic acidifiers as well as organic acidifiers have drawn much attention due to improving performance of weaning pigs with a low cost. Several researchers introduced the use of salt form of acidifiers because of convenient application and better effects than pure state acids. However, considerable variations in results of acidifier supplementation have been reported in response of weaning pigs. The inconsistent responses to dietary acidifiers could be explained by feed palatability, sources and composition of diet, supplementation level of acidifier and age of animals.

https://www.koreascience.or.kr:443/article/JAKO200510103466730.pdf

Acidifier as an Alternative Material to Antibiotics in Animal Feed

Edible insects have been used as an alternative protein source for food and animal feed, and the market size for edible insects has increased. Tenebrio molitor larvae, also known as mealworm and yellow mealworm, are considered a good protein source with nutritional value, digestibility, flavor, and a functional ability. Additionally, they are easy to breed and feed for having a stable protein content, regardless of their diets. Therefore, T. molitor larvae have been produced industrially as feed for pets, zoo animals, and even for production animals. To maintain the nutrient composition and safety of T. molitor larvae, slaughtering (heating or freezing) and post-slaughtering (drying and grinding) procedures should be improved for animal feed. T. molitor larvae are also processed with defatting or hydrolysis before grinding. They have a high quality and quantity of protein and amino acid profile, so are considered a highly sustainable protein source for replacing soybean meal or fishmeal. T. molitor has a chitin in its cuticle, which is an indigestible fiber with positive effects on the immune system. In studies of poultry, the supplementation of T. molitor larvae improved the growth performance of broiler chickens, without having negative effects on carcass traits, whereas some studies have reported that there were no significant differences in the growth performance and carcass yield of broiler chickens. In studies of swine, the supplementation of T. molitor larvae improved the growth performance and protein utilization of weaning pigs. Furthermore, 10% of T. molitor larvae showed greater amino acid digestibility than conventional animal proteins in growing pigs. However, there are some challenges regarding the biosafety, consumer's acceptance, and price for the use of T. moiltor larvae in animal feed. Consequently, T. molitor larvae could be used as an alternative or sustainable protein source in monogastric animal feed with a consideration of the nutritional values, biosafety, consumer's acceptance, and market price of T. molitor larvae products.

Mealworm (Tenebrio molitor Larvae) as an Alternative Protein Source for Monogastric Animal: A Review

This experiment was conducted to investigate the effects of dried mealworm (Tenebrio molitor larva) on growth performance, nutrient digestibility and blood profiles in weaning pigs. A total of 120 weaning pigs (28±3 days and 8.04±0.08 kg of body weight) were allotted to one of five treatments, based on sex and body weight, in 6 replicates with 4 pigs per pen by a randomized complete block design. Supplementation level of dried mealworm was 0%, 1.5%, 3.0%, 4.5%, or 6.0% in experimental diet as treatment. Two phase feeding programs (phase I from 0 day to 14 day, phase II from 14 day to 35 day) were used in this experiment. All animals were allowed to access diet and water ad libitum. During phase I, increasing level of dried mealworm in diet linearly improved the body weight (p<0.01), average daily gain (ADG) (p<0.01) and average daily feed intake (ADFI) (p<0.01). During phase II, ADG also tended to increase linearly when pigs were fed higher level of dried mealworm (p = 0.08). In addition, increasing level of dried mealworm improved the ADG (p<0.01), ADFI (p<0.05) and tended to increase gain to feed ratio (p = 0.07) during the whole experimental period. As dried mealworm level was increased, nitrogen retention and digestibility of dry matter as well as crude protein were linearly increased (p = 0.05). In the results of blood profiles, decrease of blood urea nitrogen (linear, p = 0.05) and increase of insulin-like growth factor (linear, p = 0.03) were observed as dried mealworm was increased in diet during phase II. However, there were no significant differences in immunoglobulin A (IgA) and IgG concentration by addition of dried mealworm in the growth trial. Consequently, supplementation of dried mealworm up to 6% in weaning pigs' diet improves growth performance and nutrient digestibility without any detrimental effect on immune responses.

/pdf/supplementation-of-dried-mealworm-tenebrio-molitor-larva-on-4g1lr72ruf.pdf

Yoo Yong Kim

Papers

Comparative effects of high dietary levels of organic and inorganic selenium on selenium toxicity of growing-finishing pigs.

Effect of inorganic or organic selenium at two dietary levels on reproductive performance and tissue selenium concentrations in first-parity gilts and their progeny

Acidifier as an Alternative Material to Antibiotics in Animal Feed

Mealworm (Tenebrio molitor Larvae) as an Alternative Protein Source for Monogastric Animal: A Review

Supplementation of Dried Mealworm (Tenebrio molitor larva) on Growth Performance, Nutrient Digestibility and Blood Profiles in Weaning Pigs