Organic Zn Supplementation Research Articles

Determination of optimal dietary calcium levels under different sources of zinc in Jing tint 6 layer chicks from 15 to 42 d of age

An experiment was conducted to investigate the optimal dietary calcium (Ca) levels in Jing Tint 6 layer chicks fed different sources of zinc (Zn). The diets were formulated using 2 different Zn sources: organic Zn (80 mg/kg Zn as HMZn) and inorganic Zn (80 mg/kg Zn as sulfate). For each Zn source, 5 diets were formulated to contain Ca levels of 0.80, 0.90, 1.03, 1.10, and 1.20%. Results showed that dietary Ca levels had a significant effect on body weight gain (BWG) and feed conversion ratio (FCR) (P < 0.05). In addition, BWG was significantly enhanced by the organic Zn diets (P < 0.05). Dietary Ca levels significantly affected tibia length (P < 0.05) and serum Ca and P contents (P < 0.05) but did not affect serum total protein (TP), albumin (ALB), or alkaline phosphatase (ALP) levels (P > 0.05). The apparent total tract retention coefficients (ATTRC) of Ca showed a quadratic trend (P < 0.05) with increasing Ca levels. Furthermore, organic Zn diets reduced excreta Ca output and enhanced the ATTRC of Ca in birds on d 42 compared with inorganic Zn diets. The optimal dietary Ca levels were estimated as 0.93, 0.94, and 0.96% for birds fed organic diets and 1.07, 0.99 and 0.94% for birds fed inorganic diets using nonlinear models based on the criteria of BWG, tibial length, and serum P, respectively. In general, organic Zn supplementation improved growth performance and reduced the calcium requirements of birds on d 42.

Effects of Organic Zinc on the Growth Performance of Weanling Pigs: A Meta-analysis.

Supplementation of feed with organic zinc (Zn) has long been discussed as an alternative to inorganic Zn in pigs, but its effects on growth performance are mixed. This meta-analysis was conducted to provide a comprehensive evaluation of the influence of organic Zn on the growth performance of weanling pigs, on the basis of average daily gain (ADG), average daily feed intake (ADFI), and feed to gain ratio (F/G). We screened the PubMed and Web of Science databases (published before December 31, 2022; limited to English) systematically and contrasted organic Zn supplementation with inorganic Zn supplementation. There were 680 retrievals of studies, of which 16 (1389 pigs, 37 records) were eligible to analyze. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated using a random-effects model. The subgroup analysis was classified as organic Zn source (Zn-amino acid (Zn-AA), Zn-glycine (Zn-Gly), Zn-methionine (Zn-Met), Zn-Lysine (Zn-Lys), proteinate complex Zn (Zn-Pro), chitosan-Zn (Zn-CS) or Zn-lactate (Zn-Lac)) and Zn additive dose (low, medium, or high, i.e., lower than, equal to or higher than the requirement of NRC). Organic Zn addition in the weaning phase increased the ADG (P < 0.001) and the ADFI (P = 0.023) and decreased the F/G (P < 0.001). Specifically, for the organic sources, only Zn-CS supplementation presented significant effects on the ADG (P < 0.001), ADFI (P = 0.011), and F/G (P < 0.001). Moreover, medium-dose organic Zn supplementation had positive effects on ADG (P = 0.012), ADFI (P = 0.018), and F/G (P < 0.001). Our results indicate that organic Zn added to diets greatly improves the growth performance of weanling pigs.

Organic zinc supplementation in early-lactation dairy cows and its effects on zinc content and distribution in milk and cheese

This study investigated the effects of organic zinc (Zn) supplementation in early-lactation dairy cows on Zn content and distribution in raw milk and mozzarella cheese. Thirty-four multiparous dairy cows in early lactation were randomly assigned to 2 groups: basal diet (control; CON) and basal diet supplemented with a Zn AA complex (CZ). After feeding the diets for 8 wk, raw milk was collected for manufacturing mozzarella cheese. Total Zn content and Zn distribution in raw milk and cheese were determined by atomic absorption spectrophotometry. Results showed that milk fat content was significantly increased in the CZ group compared with the CON group. No significant differences in fat, protein, and moisture contents of cheese were observed between the 2 groups. Zinc contents in milk (4.25 vs. 3.85 mg/L) and cheese (38.65 vs. 27.20 mg/kg) were significantly higher in the CZ group than in the CON group. Little Zn was lost in stretch water (<0.04 mg/L) and brine (<0.01 mg/L) during the cheese-making process. Most of the Zn was detected in casein (87.3% vs. 88.4%) of the raw milk, and then in the whey (10.6% vs. 9.88%) and fat (2.07% vs. 1.77%). Organic Zn supplementation in early-lactation cows increased Zn content in raw milk and mozzarella cheese, and Zn remained stable during cheese making.

Zinc source modulates intestinal inflammation and intestinal integrity of broiler chickens challenged with coccidia and Clostridium perfringens

Two dietary sources of zinc (ZnSO4 or organic Zn) were tested in chickens challenged with coccidiosis (Co) or coccidiosis plus Clostridium perfringens (CoCPF). On day 14, the chickens were orally gavaged with ∼5,000 Eimeria maxima sporulated oocysts. On day 19, 20, and 21 chickens challenged with C. perfringens were given a broth culture containing 108 cfu of this bacterium. Productive performance parameters were determined at d 14, 21, and 28. On day 21, necrotic enteritis (NE) lesions were scored, and intestinal permeability was evaluated. Jejunum and cecal tonsils were collected for morphology and gene expression analysis. On day 21, organic Zn improved BW gain by 18.6% (P = 0.07), and FCR by 12% (P = 0.09) in CoCPF challenged chickens vs. birds fed ZnSO4. From 1 to 28, organic Zn increased BW gain (P = 0.02), and improved FCR (P = 0.03) vs. birds fed ZnSO4. At 21 d, NE lesions were only observed in CoCPF birds (P < 0.001), and mortality due to NE was only observed when CoCPF birds were fed ZnSO4 (P = 0.001). Organic Zn fed birds had increased villus height in the jejunum (P = 0.005) and decreased intestinal permeability (P = 0.01) vs. ZnSO4. In the jejunum, organic Zn fed birds showed a downregulation of expression of IL-8 (P = 0.02), and upregulation of IL-10 (P = 0.05) in CoCPF birds vs. ZnSO4- CoCPF birds. As main effect, birds supplemented with organic Zn had higher mRNA expression of TLR-2 (P = 0.02) and IgA (P = 0.01). In the cecal tonsils, organic Zn fed birds showed upregulation of iNOS (P = 0.008) in CoCPF birds vs. ZnSO4-CoCPF birds. Organic Zn supplementation reduced intestinal permeability and attenuated intestinal inflammation of broilers co-challenged with coccidia and C. perfringens.

Field Study on Growth Performance of Pre-Weaned Stall Fed Local Kids Supplemented with Organic Zinc

Small ruminants especially goat plays an important economic and sustainable income to the Indian farming community especially small, marginal and landless labourers in the country. Wants of human been raising to meet the food requirements of the increasing population. But in the other side the nutritional status of these animals plays a vital role in their production performances. Among the essential micronutrients Zinc influences metabolism, immune system and overall health condition, deficiency of which can result in growth retardation, and other health related problems leading to huge economic losses. Hence the current study was carried out to assess the effect of organic Zn supplementation on growth rate of pre-weaned stall fed local kids. Twelve twin local kids of one week age were divided in to two equal groups of six in each group (Control and Treatment) with the average body weights of 2.20±0.01kg (Control) and 2.16±0.03 kg (Treatment). The Control group animals were allowed to suckle mother during first three weeks of study. Then along with suckling, they were provided with tree leaves (Neem and Sesbania), horse gram and chopped fodder maize till the completion of study. Whereas, the animals in Treatment group were also offered same diet as that of control group, additionally these group was supplemented with organic Zn (Zn acetate) @ 1 mg/kg body weight. Weekly body weight of both groups was recorded for 10 weeks and the data so collected was analyzed statistically. The results showed that the Average Daily Gain (ADG) (g) of kids supplemented with organic Zn was higher (89.73 ± 0.57) than the control (44.38 ± 1.23). This shows that the supplementation of Zinc in the form of Zinc acetate has a significant influence on growth and development of kids; hence study recommends the supplementation of zinc for young small ruminants mainly kids.

Positive effect of organic zinc supplementation on the persistence of anti-rabies neutralizing antibodies in healthy sheep

The main prophylactic tool to control rabies in herbivores is the systematic vaccination of susceptible animals. This study aimed to evaluate the positive effect of organic zinc (Zn) supplementation on the persistence of anti-rabies neutralizing antibodies in healthy sheep. A total of 36 Texel ewes were selected and randomly divided into 2 groups of 18 animals each. The treated group (TG) received organic Zn supplementation for 90 days, and after this period, 2 doses of rabies vaccine with a 30-day interval. The control group (CG) received the vaccine doses only and was not supplemented with organic Zn. Blood samples were collected before the first vaccination and 30, 60, and 90 days after vaccination, to determine the anti-rabies neutralizing antibody titer using the Rapid Fluorescent Focus Inhibition Test (RFFIT). The average values of anti-rabies serum-neutralizing antibodies 30 days after the first dose were 1.33 ± 0.62 IU mL-1 for the CG and 1.57 ± 0.80 IU mL-1 for the TG; 60 days after the second dose the average values were 7.60 ± 7.08 IU mL-1 and 12.97 ± 9.46 IU mL-1 for the CG and TG, respectively, with a significant difference between groups. The TG presented 100% vaccine coverage of the primary vaccination, whereas the CG presented 89.47% coverage. Oral supplementation with 75 mg organic Zn significantly increased the persistence of anti-rabies antibody titers in sheep, and it improved the vaccine coverage of the primary vaccination.

Subsequent somatic axis and bone tissue metabolism responses to a low-zinc diet with or without phytase inclusion in broiler chickens.

Zinc is required for normal bone development and cartilage formation. The purpose of this study was to assess the effect of with adding organic Zn (alone or phytase inclusion) at the reduced dose to growing male Ross 308 chickens on somatic axis and bone tissue metabolism. 200 one-day old broilers were divided into the negative control group fed diet without Zn or phytase inclusion, positive control group receiving Zn in the 100% of daily recommended dose from ZnO, and two experimental groups fed diet introduced Zn in 25% of daily recommendation as a glycine chelate (Zn-Gly) with or without phytase inclusion (500 FTU·kg-1). Supplemental organic Zn increased bone Zn and Mg content, serum IGF-1, growth hormone and leptin concentration. Additional phytase inclusion increased body weight gain, blood plasma Ca, Fe, Zn and osteocalcin concentration and tibia ash percentage when compared to the Zn-deprived control. Bone geometry, yield and ultimate strengths were enhanced in both organic Zn supplemented groups, and the overall mechanical strength parameters of bone were better in these groups than in the positive control group supplemented with standard dose of inorganic Zn. Also marked improvements in the thickness of articular and the growth plate cartilages as well as real bone volume and thickness of metaphyseal trabeculae were achieved in all broilers fed Zn-supplemented diet irrespective of phytase inclusion, however, the highest cancellous bone mass and the best trabecular structure were noted after ZnO supplementation. In concludion, although dietary organic Zn given to growing broilers in 25% of daily recommended dose improved general bone properties and mechanical strength, the obtained results do not allow to unambiguously state that organic Zn supplementation at this level, even after phytase inclusion, is sufficient for proper bone development.

Effect of dietary zinc-methionine supplementation on growth performance, nutrient utilization, antioxidative properties and immune response in broiler chickens under high ambient temperature

ABSTRACTThis study was conducted to evaluate the effect of zinc-methionine (ZnM) on growth performance, nutrient utilization, antioxidant status and immune response in broiler chickens reared at high ambient temperature. A total of 480 one-day-old chicks were randomly distributed into 24 floor pens (20 chicks/pen) and were given either a control diet, 0 ZnM (G0) or 25, 50 and 100 mg/kg ZnM (G1, G2 and G3, respectively). The growth performance was significantly affected by the treatments, ZnM supplementation increased body weight gain and improved feed conversion (p < .05) in broilers. Protein utilization was improved by feeding ZnM (p < .05). Plasma total cholesterol was decreased, while plasma HDL-cholesterol was tending to be increased. Interestingly, an increase in ZnM supplementation enhanced Zn concentrations (p < .05) in breast muscle along with a reduction in malondialdehyde concentration and saturated fatty acids (p < .05) and an augmentation in unsaturated fatty acids (p < .01). Dietary ZnM supplementation resulted in a significant increase in serum glutathione peroxidase concentration which accompanied with an improving in humoral immune response. It could be concluded that dietary organic Zn supplementation improved growth performance, nutrient digestibility, Zn content in raw meat, antioxidative properties and humoral immunity and reduced meat lipid peroxidation in broilers under high ambient temperature.

Source of supplemental dietary copper, zinc, and manganese affects fecal microbial relative abundance in lactating dairy cows

Appropriate trace mineral supplementation can improve immune response and hoof health in cattle and at much higher rates of supplementation to swine and poultry can alter microbial colonization of the gut, resulting in improved gut health. Diet can influence fecal microbial excretion in cattle, and the fecal microbiome may serve as a means for assessing gastrointestinal microbial changes. We hypothesized that feeding diets that differed in source of supplemental Cu, Zn, or Mn would alter the relative abundance of fecal microbes in lactating dairy cattle and that organic Zn would have the greatest effect. Twenty-four cows were fed diets devoid of supplemental Cu, Zn, and Mn for a 16-d preliminary phase (basal diet provided 9, 29, and 32 mg/kg of Cu, Zn, and Mn, respectively), and then were randomly assigned to 1 of 3 treatment diets (n = 8 cows/treatment): one group of cows was fed supplemental Cu, Zn, and Mn from sulfate minerals; the second group was fed glycinate minerals; and the third group was fed Cu and Mn sulfate with glycinate Zn. Assayed total dietary concentrations were approximately 21, 73, and 72 mg/kg for Cu, Zn, and Mn, respectively. Milk production (averaged 38.8 kg/d), DMI (averaged 25.8 kg/d), and milk components were not affected by treatment. Fecal DNA was extracted, amplified using a universal primer targeting the V4-V5 hypervariable region of the 16S rRNA gene, and sequenced to compare microbial community composition between treatments. Relative abundances of Treponema species-level operational taxonomic units (OTU) were less for animals fed Cu and Mn sulfate with glycinate Zn compared with sulfates alone, but were similar to animals fed glycinate mineral sources. Relative abundances for exclusive glycinate mineral and sulfate mineral treatments were similar. Treponema OTU and cultured representatives are often associated with bovine digital dermatitis. These data may provide an additional link between organic Zn supplementation and improved hoof health. To our knowledge this is the first report of a dietary treatment decreasing the relative abundance of Treponema OTU in cattle feces; however, the potential benefits of this response on overall animal health and the mechanism for the observed responses are unknown and warrant further investigation.

Comparative evaluation of organic zinc supplementation as proteinate with inorganic zinc in buffalo heifers on health and immunity

Graded Murrah buffalo heifers (18) were randomly allotted to 3 dietary groups varying in source and level of Zn supplementation in concentrate mixture to study the effect of organic (O) Zn (Zn proteinate; Zn-prot) supplementation (80 or 140 ppm) compared to inorganic Zn (I) (ZnSO4) (140 ppm) on serum biochemical parameters, antioxidant status and ovarian folliculogenesis. Mineral and biochemical constituents in serum and antioxidant enzyme activities in haemolysate were measured on 90th d of experiment. Antibody titres (log2) against Brucella abortus S19 and chicken RBC antigens was measured in serum at 7, 14, 21 and 28th d post sensitization (humoral immunity) and cell mediated immunity was assessed (120 d) by in-vivo delayed type hypersensitivity (DTH) against phytohemagglutinin-P (PHA-P). After 60 days of feeding, ovarian folliculogenesis study was made daily with ultrasound scanner in all the animals for next 60 days. Highest Zn concentration in serum without affecting the retention of other minerals (Cu, Mn and Fe) was observed with 140 ppm Zn supplementation as Zn-prot and mineral concentrations was comparable between 80 ppm Zn as Zn-prot and 140 ppm Zn as ZnSO4. Alkaline phosphatase, total protein, globulin, and glucose concentrations in serum increased with organic Zn supplementation. Organic Zn lowered lipid peroxidation (140O&lt;80O&lt;140I) and improved RBC catalase, glutathione peroxidase and superoxide dismutase (140O&gt;80O&gt;140I) activities. Antibody titres against B. abortus and chicken RBC and in vivo DTH response improved with organic Zn supplementation. Similarly, irrespective of the dose, organic Zn supplementation significantly increased the number of large follicle with greater follicular size in ovary. The study indicated that 140 ppm Zn supplementation as Zn-prot resulted in better antioxidant status, immune response and folliculogenesis in ovaries than inorganic source and the Zn supplementation could be reduced from 140 to 80 ppm as Zn-prot without any adverse effect in buffalo heifers.

Replacement of inorganic zinc with lower levels of organic zinc (zinc nicotinate) on performance, hematological and serum biochemical constituents, antioxidants status, and immune responses in rats.

Aim:A study was undertaken to investigate the effect of organic zinc (zinc nicotinate, Zn-nic) supplementation (6, 9, and 12 ppm) compared to inorganic zinc (12 ppm) on growth performance, hematology, serum biochemical constituents oxidative stress, and immunity in weaned female Sprague–Dawley rats.Material and Methods:A 48 weaned rats (285.20±1.95 g) were randomly distributed to 4 dietary treatments with 6 replicates in each and reared in polypropylene cages for 10 weeks. Basal diet (BD) was formulated with purified ingredients without zinc (Zn). Four dietary treatments were prepared by adding 12 ppm Zn from ZnCO3 (control) and 6, 9, and 12 ppm Zn from Zn-nic to the BD. On 42nd day, blood was collected by retro-orbital puncture for analyzing hematological constituents, glucose, cholesterol, alkaline phosphatase, total protein, albumin, and globulin and antioxidant enzyme activities. At 43rd day, rats were antigenically challenged with sheep red blood cell (RBC) to assess humoral immune response and on 70th day cell-mediated immune response.Results:Weekly body weight gains, daily feed intake, blood hematological constituents (white blood cell, RBC, hemoglobin concentration, packed cell volume, mean corpuscular volume, lymphocyte, monocyte, and granulocyte concentration) and serum glucose, total protein levels were comparable among the rats feed Zn from ZnCO3 and Zn-nic (6, 9, and 12 ppm). Serum cholesterol reduced with organic Zn supplementation at either concentration (6-12 ppm). Serum globulin concentration reduced (p<0.05) with 6 ppm Zn-nic supplementation compared to other dietary treatments. Lipid peroxidation lowered (p<0.05) reduced with 12 ppm organic Zn; thiobarbituric acid reacting substances and protein carbonyls concentrations in liver reduced (p<0.05) with 9 and 12 ppm levels of organic Zn supplementation compared to 12 ppm Zn supplementation from inorganic source. RBC catalase and glutathione peroxidase enzymes activities were highest (p<0.05) in rats supplemented with 12 ppm Zn-nic, followed by 9 ppm. Comparable immune response (humoral and cell-mediated) was observed between 12 ppm inorganic Zn and 9 ppm organic Zn and higher (p<0.05) immune response was noticed at 12 ppm Zn-nic supplementation.Conclusion:Based on the results, it is concluded that dietary Zn concentration can be reduced by 50% (6 ppm) as Zn nicotinate without affecting growth performance, hemato-biochemical constituents, antioxidant status, and immunity. In addition, replacement of 12 ppm inorganic Zn with 12 ppm organic Zn significantly improved antioxidant status and immune response.

Les patients présentant des ulcères digitaux actifs ont une sclérodermie plus sévère que les patients ayant un antécédent d’ulcères digitaux mais pas d’ulcère actif : résultats du registre « Digital Ulcers Observatory » (DUO)

Two dietary sources of zinc (ZnSO4 or organic Zn) were tested in chickens challenged with coccidiosis (Co) or coccidiosis plus Clostridium perfringens (CoCPF). On day 14, the chickens were orally gavaged with ∼5,000 Eimeria maxima sporulated oocysts. On day 19, 20, and 21 chickens challenged with C. perfringens were given a broth culture containing 108 cfu of this bacterium. Productive performance parameters were determined at d 14, 21, and 28. On day 21, necrotic enteritis (NE) lesions were scored, and intestinal permeability was evaluated. Jejunum and cecal tonsils were collected for morphology and gene expression analysis. On day 21, organic Zn improved BW gain by 18.6% (P = 0.07), and FCR by 12% (P = 0.09) in CoCPF challenged chickens vs. birds fed ZnSO4. From 1 to 28, organic Zn increased BW gain (P = 0.02), and improved FCR (P = 0.03) vs. birds fed ZnSO4. At 21 d, NE lesions were only observed in CoCPF birds (P < 0.001), and mortality due to NE was only observed when CoCPF birds were fed ZnSO4 (P = 0.001). Organic Zn fed birds had increased villus height in the jejunum (P = 0.005) and decreased intestinal permeability (P = 0.01) vs. ZnSO4. In the jejunum, organic Zn fed birds showed a downregulation of expression of IL-8 (P = 0.02), and upregulation of IL-10 (P = 0.05) in CoCPF birds vs. ZnSO4- CoCPF birds. As main effect, birds supplemented with organic Zn had higher mRNA expression of TLR-2 (P = 0.02) and IgA (P = 0.01). In the cecal tonsils, organic Zn fed birds showed upregulation of iNOS (P = 0.008) in CoCPF birds vs. ZnSO4-CoCPF birds. Organic Zn supplementation reduced intestinal permeability and attenuated intestinal inflammation of broilers co-challenged with coccidia and C. perfringens.

Influence of organic zinc supplementation on the antioxidant status and immune responses of broilers challenged with Eimeria tenella

An experiment was conducted to investigate the influence of Zn supplementation on the performance, antioxidant status, and immune responses of broilers challenged with Eimeria tenella. A total of 384 male broilers (1 d old) were assigned to 8 treatments consisting of 8 replicates of 6 chicks each. A basal corn-soybean meal diet (29.6 mg of Zn/kg) was supplemented with methionine hydroxyl analog-Zn chelate at 0, 20, 40, and 60 mg/kg of diet. At 21 d of age, birds were orally gavaged with 1.5 × 10(4) sporulated E. tenella oocysts. Dietary Zn supplementation had no effect on growth performance of either the challenged or nonchallenged birds. Activities of Cu-Zn superoxide dismutase and glutathione peroxidase were increased (P < 0.001) with increasing Zn levels in both the challenged and nonchallenged groups. Lipid peroxidation tended to be reduced (P = 0.08) at Zn inclusion of 20 and 40 mg/kg. In vitro lymphocyte proliferation responses to mitogen concanavalin A and LPS were not influenced by dietary Zn or challenge. The main effects of Zn level and challenge were significant for secretory IgA on d 28 (P < 0.01) and 35 (P < 0.001). During both periods, secretory IgA of birds receiving dietary Zn supplementation was higher (P < 0.05) than that of those receiving no Zn supplementation. Birds fed Zn supplementation excreted fewer oocysts in the excreta than those receiving no Zn supplement (P < 0.001). Results indicated that organic Zn supplementation reduced oxidative stress and improved some immune responses irrespective of whether birds were healthy or challenged with E. tenella.

Effects of dietary supplements of zinc-methionine on milk production, udder health and zinc metabolism in dairy goats.

Twenty-two Murciano-Granadina dairy goats were used to investigate the effects of organic Zn supplementation of a diet containing a high level of inorganic Zn. Goats were kept in pens, machine milked once a day throughout lactation and fed a diet based on a dehydrated mixture of whole-plant maize and alfalfa ad libitum, alfalfa pellets, barley grain and a concentrate mixture. Treatments were: (1) control, and (2) supplemented with 1 g/d Zn-Methionine (Zn-Met) included in the concentrate mixture. After parturition, goats were blocked in week 3 and dietary treatments were applied until week 23. From weeks 3-20, feed intake, milk yield, milk composition, milk somatic cell count (SCC), and udder health were measured. In week 21, all goats were injected intraperitoneally with 1 g/d DL-methionine for 5 d to establish the effects of methionine under the conditions of udder stress induced by hand milking on the second day. During weeks 22 and 23, diet digestibility, and N and Zn balance were determined. Dry matter intake, milk yield, and milk contents of total solids, fat, total and true protein, and casein did not differ between treatments, but whey protein and non-protein nitrogen contents were significantly lower for the Zn-Met group. Milk SCC tended to decrease as a result of Zn-Met supplementation but differences between treatments were not significant when halves with persistent infection were excluded. Hand milking increased SCC in both groups, but udders of supplemented goats showed a lower reaction. Apparent absorption of N significantly increased and Zn retention tended to increase in Zn-Met supplemented goats. We conclude that Zn-Met supplementation can enhance resistance to udder stress in dairy goats. Effects were attributed to the organic Zn and not to the methionine component. Zn retention and protein utilization were also improved by the Zn-Met supplement.