Effects Of Zn Source Research Articles

Effect of zinc source (zinc sulfate or zinc hydroxychloride) on relative abundance of fecal Treponema spp. in lactating dairy cows

Previous research revealed a potential effect of dietary trace mineral source on both ruminal and fecal microbiota. However, the effect of Zn source, specifically, has not previously been considered. Based on reported postruminal solubility, we hypothesized that Zn hydroxychloride would decrease Treponema spp. fecal excretion relative to cows fed Zn sulfate. To test this hypothesis, lactating Holstein cows (n = 24; 685 ± 9 kg of body weight; 159 ± 8 d in milk; parity 3 ± 0.2) were randomly assigned to 1 of 2 dietary treatments: control (75 mg/kg Zn from ZnSO4) or Zn hydroxychloride (HYD; 75 mg/kg IntelliBond Z; Micronutrients USA LLC). Single fecal grab samples were collected on d 1 before dietary treatments and on d 27 after dietary treatments were applied. Fecal microbial DNA was extracted and sequenced to establish taxonomy using a universal primer for the 16S rRNA gene. Supplementation of HYD decreased the relative abundance of Treponema 2 by 3-fold (14.7% vs. 4.9%). Poor sequencing resolution at the species level limited inference of Treponema spp. toward management or gut health implications of HYD supplementation. However, the inclusion of pathogenic species among Treponema spp. indicates a potential implication of HYD feeding to reduce environmental exposure of the dairy cow to Treponema spp.

Early growth and development of maize on sandy soils fertilised with zinc sources at different application rates

The grain yield and quality of maize is often negatively influenced by zinc (Zn) deficiencies during early growth and development. Application of Zn to soil is therefore a necessity, especially when it is sandy. Glasshouse experiments were carried out to test the effects of Zn sources and application rates on plant-available Zn and on early growth and development of maize grown in a sandy soil. Soil Zn concentration was increased most by ZnSO4 and least by ZnO. The Na2EDTA method was superior to four other methods in extracting soil Zn. For most plant parameters that were measured (leaf number, stem thickness, plant height, photosynthesis rate, leaf area, dry mass, root length and root mass) ZnEDTA was the most effective chelated source, followed by ZnHEDTA, ZnDTPA or ZnEDDHA. Regarding inorganic sources ZnSO4 was superior, followed by ZnCO3, ZnCl2 and ZnO. As a group the inorganic sources performed more poorly than the chelated sources. These rankings differed in terms of Zn concentration and uptake by the plants. The results must be verified in field trials that last for several years accommodating a wider range of climate and soil conditions to develop reliable Zn fertilisation guidelines for maize cultivated on sandy soils.

Cyclic Heat Stress and Supplementation of Zinc at a High or Low Level from Inorganic and Organic Sources Minimally Impact Display Shelf-Life of Fresh and Processed Pork

ObjectivesHeat stress (HS) induces metabolic changes associated with physiologic adaptation to stress and pigs exposed to acute heat experience musculoskeletal oxidative stress. Zinc may be particularly beneficial to HS animals due to its involvement in nutrient and insulin mediated metabolism. Thus, our objective was to determine the effects of Zn supplementation on color and oxidative stability of fresh and processed pork products from pigs subjected to a summer HS.Materials and MethodsCommercial crossbred pigs (initially 72.0 kg) were housed 5 pigs/pen under thermoneutral (TN; 18.9 to 16.7°C) or cycling HS conditions simulating chronic summer heat (30°C/26.7°C for 12 h:12 h on d 24 to 63) with acute heat waves (32 to 33°C/29 to 30°C for 12 h:12 h on d 21 to 24, 42 to 45, & 63 to 65). Core body temperatures were recorded to validate HS. Pens (experimental units) were randomly allotted to eight treatments arranged as a 2 × 2 × 2 factorial with main effects of environment (ENV; TN vs. HS), supplemented Zn level (LEV; 50 vs. 130 mg/kg available Zn), and Zn source (SRC; inorganic from ZnO vs. organic/inorganic-blend). One pig per pen (n = 80) was slaughtered on d 65, and at 1 d postmortem chops were fabricated from the 4th-10th rib portion of the loin (M. longissimus dorsi). Dissected lean and fat from the picnic shoulder of each carcass was combined as a 70/30 lean:fat blend with a nitrate-free sausage seasoning blend and formed into 2.54 cm thick patties. Chops and patties were packaged on styrofoam trays with PVC film overwrap and stored at 4°C under 40-W fluorescent light for 0, 3, 7, or 10 d. At each display endpoint, assessment was made of CIE L*a*b* color attributes on all products with a Hunter MiniScan colorimeter (D65 illuminant/10°) and of lipid oxidation via 2-thiobarbituric acid reactive substances (TBARS) assay on all patties and a subset of chops (n = 48). Data were analyzed as a RCBD in SAS 9.4 (SAS Inst. Inc., Cary, NC) using preplanned contrasts.ResultsColor and oxidative changes occurred over time in all products but no interactions (P > 0.10) between display day and treatment were observed. For chops, d 3 L* was less when Zn was fed at the 50 mg/kg level from organic source, but less at the 130 mg/kg level from inorganic source (LEV × SOR, P = 0.014). Inorganic Zn increased d 10 a* (6.16 vs. 5.83, P = 0.008) and decreased discoloration (hue angle, P = 0.004) compared to organic Zn. Day 3 b* was less for 50 mg/kg vs. 130 mg/kg (P = 0.048) and ENV×SOR interactions (P < 0.05) were observed for d 3 discoloration, d 7 b*, and d 10 b* and chroma. For sausage patties, d 3 L* was decreased at the 50 mg/kg Zn level relative to 130 mg/kg. No differences were observed in sausage a* but HS decreased (P < 0.01) d 0 and d 10 b* and d 10 chroma compared to TN. Initially, sausage derived from HS animals tended (d 0, P = 0.071) to have less lipid oxidation than TN but within each subsequent display day, no lipid oxidation differences (P > 0.05) due to treatment were observed in either loin chops or sausage.ConclusionIn conclusion, the HS model did not appear to reduce display shelf-life of fresh and minimally processed pork as indicated by lack of differences in lipid oxidation and color stability. The effects of Zn source on chop color differed by environment and Zn level but greater amounts of Zn failed to impart any benefit to oxidative stability and color.