Methodology for assessing zinc bioavailability: efficacy estimates for zinc-methionine, zinc sulfate, and zinc oxide

Abstract

The bioavailability of zinc-methionine (ZnMET) was compared to that of feed-grade ZnSO4.H2O using three different diets: purified (crystalline amino acid [AA]), semipurified (soy isolate), and complex (corn-soybean [C-SBM]) diet. With the Zn-deficient purified or semipurified diet, weight gain and tibia Zn responded linearly to both ZnSO4.H2O and ZnMET supplementation. Common-intercept, multiple linear regression indicated differences in Zn bioavailability between ZnMET and ZnSO4.H2O for both diets as indicated by bone Zn. With the ZnSO4.H2O standard set at 100%, bioavailability of Zn from ZnMET was 117% (P less than .05) in the AA diet and 177% (P less than .01) in the soy isolate diet. The ZnMET was also compared to ZnSO4.H2O in a C-SBM diet containing 117 mg of Zn/kg. When high levels of Zn were added to this diet (0, 250, 500, and 750 mg/kg of supplemental Zn), consistent tissue Zn responses did not occur beyond the first increment. Addition of lower levels of supplemental Zn (0, 5, 10, 20, 30, 40 and 50 mg/kg) to a Zn-unsupplemented C-SBM basal diet (45 mg/kg of Zn), however, resulted in a broken-line, two-slope response in tibia Zn for both ZnMET and ZnSO4.H2O. Inflection points occurred at 60 and 54 mg of Zn/kg of diet for ZnSO4.H2O and ZnMET, respectively. The ratio of slopes (ZnMET:ZnSO4.H2O) below the inflection points was 206% (P less than .01), indicating that Zn was considerably more bioavailable in ZnMET than in ZnSO4.H2O for chicks consuming C-SBM diets. When feed-grade ZnO was compared to feed-grade ZnSO4.H2O in chicks consuming C-SBM diets, bone Zn slopes below the respective inflection points indicated that Zn was 61% bioavailable in ZnO relative to ZnSO4.H2O.

Effect of replacing dietary FeSO₄ with equal Fe-levelled iron glycine chelate on broiler chickens

“…Recent research on organic minerals proved that chelate minerals can be more effectively absorbed in the intestines than inorganic oxide and sulfate (Wedekind et al 1992;Aoyagi and Baker 1993). Accordingly, chelated Fe, especially Fe-Gly, has been used more frequently as the Fe fortification in animal nutrition.…”

Chelated minerals for poultry

“…For instance, it is well known that phytate seize positive charged metals and, consequently high phytate diets tend to confound the effects of the salt sources being tested. Zinc-methionine supplemented to cornsoybean meal diets presented 206% bioavailability, but only 117% when included in a purified diet without phytate (Wedekind et al, 1992). In all-vegetable feeds, which bear a high proportion of phytate, the advantage of mineral chelates tends to be easier observed as compared to diets with animal by-products inclusion.…”

Top-dressing of the different feed additives is effective to prevent lameness and to increase feedlot cattle performance during a short-term period

“…In addition, increased claw problems are observed in a Co deficiency due to decreased protein synthesis (Smart and Cymbaluk 1997). Amino acid complexes of trace minerals are more bioavailable (Wedekind et al 1992) and compared with sources result in similar outcome in lower amounts (Nocek et al 2006). Given that those causes were mentioned the improved claw integrity was expected.…”

“…Brethour et al (1986) observed an 11.6% increase in ADG and 5.3% decrease in DM/gain by the addition of 10.5-g sodium bicarbonate per kilogram feed DM to wheat sorghum-based diets. Amino acid complexes of trace minerals are more bioavailable (Wedekind et al 1992) and are better retained by the body (Nockels et al 1993) than inorganic sources of trace minerals. This improved bioavailability may stimulate weight gain and feed conversion ratio in cattle (Kessler et al 2003).…”

“…Copper, manganese and cobalt may also improve digital integrity, as they play important roles in immune function and proliferation of horn and connective tissues (Nocek et al 2000). Trace minerals bounded with organic compounds are more readily absorbed from the digestive tract (Ashmead 1993) and may be more biologically available compared with the inorganic salts of these minerals (Wedekind et al 1992). Thus, supplying bulls with amino acid complexes of essential trace minerals may improve biological processes such as connective tissue growth.…”