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J. Anim. Sci. 2002. 80:1917-1924
© 2002 American Society of Animal Science

Effect of feeding organic and inorganic sources of additional zinc on growth performance and zinc balance in nursery pigs1

C. L. Case and M. S. Carlson2

Department of Animal Science, University of Missouri, Columbia 65211

2 Correspondence:
S133 Animal Sciences Center (phone: 573-882-7859; fax: 573-884-4545; E-mail:
carlsonm{at}missouri.edu).


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 Implications
 Literature Cited
 
Three experiments were conducted to evaluate the effect of feeding pharmacological concentrations of zinc (Zn), from organic and inorganic sources, on growth performance, plasma and tissue Zn accumulation, and Zn excretion of nursery pigs. Blood from all pigs was collected for plasma Zn determination on d 14 in Exp. 1, d 7 and 28 in Exp. 2, and d 15 in Exp. 3. In Exp. 1, 2, and 3, 90, 100, and 15 crossbred (GenetiPorc USA, LLC, Morris, MN) pigs were weaned at 24 ± 0.5, 18, and 17 d of age (6.45, 5.47, and 5.3 kg avg initial BW), respectively, and allotted to dietary treatment based on initial weight, sex, and litter. A Phase 1 nursery diet was fed as crumbles from d 0 to 14 in Exp. 1, 2, and 3, and a Phase 2 nursery diet was fed as pellets from d 15 to 28 in Exp. 1 and 2. The Phase 1 and Phase 2 basal diets were supplemented with 100 ppm Zn as ZnSO4. Both dietary phases contained the same five dietary treatments: 150 ppm additional Zn as zinc oxide (ZnO), 500 ppm added Zn as ZnO, 500 ppm added Zn as a Zn-amino acid complex (Availa-Zn 100), 500 ppm added Zn as a Zn-polysaccharide complex (SQM-Zn), and 3,000 ppm added Zn as ZnO. Overall in Exp. 1, pigs fed 500 ppm added Zn as SQM-Zn or 3,000 ppm added Zn as ZnO had greater ADG (P < 0.05) than pigs fed 150 ppm, 500 ppm added Zn as ZnO, or 500 ppm added Zn as Availa-Zn 100 (0.44 and 0.46 kg/d vs 0.35, 0.38, and 0.33 kg/d respectively). Overall in Exp. 2, pigs fed 3,000 ppm added Zn as ZnO had greater (P < 0.05) ADG and ADFI than pigs fed any other dietary treatment. On d 14 of Exp. 1 and d 28 of Exp. 2, pigs fed 3,000 ppm added Zn as ZnO had higher (P < 0.05) plasma Zn concentrations than pigs on any other treatment. In Exp. 3, fecal, urinary, and liver Zn concentrations were greatest (P < 0.05) in pigs fed 3,000 ppm added Zn as ZnO. On d 10 to 15 of Exp. 3, pigs fed 3,000 ppm added Zn as ZnO had the most negative Zn balance (P < 0.05) compared with pigs fed the other four dietary Zn treatments. In conclusion, feeding 3,000 ppm added Zn as ZnO improves nursery pig performance; however, under certain nursery conditions the use of 500 ppm added Zn as SQM-Zn may also enhance performance. The major factor affecting nutrient excretion appears to be dietary concentration, independent of source.

Key Words: Excretion • Growth • Piglets • Plasma • Zinc


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 Implications
 Literature Cited
 
Feeding supplemental zinc to nursery pigs began when reports from Europe (Poulsen, 1995) suggested high concentrations of dietary zinc (Zn) in the form of zinc oxide (ZnO) decreased the incidence of nonspecific postweaning scours. Researchers in the United States showed that high concentrations of inorganic Zn as Zn oxide improved growth performance of nursery pigs (Smith et al., 1997; Carlson et al., 1999; Hill et al., 2000). The Zn requirement for nursery pigs given in the Nutrient Requirements for Swine (NRC, 1998) is set at 100 ppm Zn; however, the addition of 2,000 to 3,000 ppm Zn as ZnO is a common recommendation of the swine feed industry. The use of high concentrations of inorganic Zn has raised some environmental concerns due to low Zn retention rates and bioavailability of ZnO. Therefore, interest in using organic minerals has increased because of the reported potential of higher bioavailability than from inorganic mineral sources (Hahn and Baker, 1993). Ward et al. (1996) reported that the beneficial effect on growth from supplementation of high concentrations of ZnO could also be achieved by feeding lower concentrations of organic Zn (250 ppm of Zn-methionine) with normal concentrations of inorganic Zn (160 ppm of Zn-sulfate). The objective of this research was to evaluate different concentrations of organic and inorganic Zn sources on growth performance and Zn excretion of nursery pigs.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 Implications
 Literature Cited
 
Animals
This research was approved by the Animal Care and Use Committee of the University of Missouri – Columbia prior to initiation (protocol #3311).

Experiment 1
In Exp. 1, 90 crossbred (GenetiPorc USA, LLC, Morris, MN) pigs (avg 6.45 ± 0.17 kg and 24 ± 0.5 d of age) were weaned and allotted to one of five dietary treatments based on initial weight, sex, and litter. Pigs were housed in an environmentally regulated building with concrete-slatted flooring over a pit. There were six replications with 30 pens and three pigs in each pen. Pigs were allowed 0.32 m2/pig. Each pen had one four-hole self-feeder and one nipple waterer.

Experiment 2
In Exp. 2, 100 crossbred (GenetiPorc USA) pigs (avg 5.47 ± 0.01 kg and 18 d of age) were weaned and allotted to one of five dietary treatments based on initial weight, sex, and litter. Pigs were housed in an environmentally regulated nursery facility with woven-wire flooring over a shallow flush system. There were five replications with 25 pens and four pigs in each pen. Pigs were allowed 0.23 m2/pig. Each pen had two one-hole self-feeders and two nipple waterers.

Experiment 3
In Exp. 3, 15 crossbred (GenetiPorc USA) barrows (avg 5.31 ± 0.006 kg and 17 d of age) were weaned and allotted to one of five dietary treatments based on initial weight and litter. Pigs were placed in individual stainless steel metabolism cages equipped with stainless steel feeders and waterers in the environmentally controlled room at the University of Missouri Animal Science Research Center. After a 10-d adaptation period to the individual cages and experimental diets, feces and urine were collected for five 24-h periods. There were three replications per treatment.

Diets
Pigs were fed typical Phase 1 (Exp. 1, 2, and 3) and Phase 2 (Exp. 1 and 2) nursery diets. Each phase had five dietary treatments. The basal diet contained 100 ppm Zn as ZnSO4. The five dietary treatments were developed by supplementing the basal diet with the following concentrations and sources of zinc: 1) 150 ppm Zn as ZnO (feed-grade, 72% Zn), 2) 500 ppm Zn as ZnO, 3) 500 ppm Zn as Availa-Zn 100 (ZINPRO, Eden Prairie, MN), 4) 500 ppm Zn as SQM-Zn (QualiTech, Chaska, MN), and 5) 3,000 ppm Zn as ZnO. Availa-Zn 100 (10% Zn) is a zinc amino acid complex which, described by the Association of American Feed Control Officials (AAFCO), is a product resulting from the complexing of a soluble metal salt with an amino acid(s). Sea-Questra-Min Zn, or SQM-Zn (22% Zn), is a metal polysaccharide complex that is described by AAFCO as a product resulting from complexing a soluble salt with a polysaccharide solution declared as an ingredient as the specific metal complex. Phase 1 nursery diets were pelleted and fed as crumbles from d 0 to 14 after weaning. Phase 2 nursery diets were fed as pellets from d 15 to 28 after weaning. All nutrients met or exceeded NRC (1998) recommendations for nursery pigs (Table 1Go).


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  		Table 1. Percentage composition of experimental dietsa (as-fed basis)
 
Growth and Plasma
Pig weights and feed disappearance were measured weekly for the duration of the 28-d experiment (Exp. 1 and 2). In Exp. 3, pigs were weighed initially and on d 15 and feed consumption was measured daily. Using these values, ADG, ADFI, and gain/feed were determined. Blood samples were collected from all pigs on d 14 in Exp. 1, d 7 and 28 in Exp. 2, and d 15 in Exp. 3 from the anterior vena cava into 10-mL sodium-heparanized (143 units of sodium-heparin/tube) vacutainer tubes and placed on ice. Blood was centrifuged (Dupont Sorvall RT 6000) at 2,500 x g for 20 min at 5°C. The separated plasma was stored at -20°C in 5-mL propylene tubes until analysis could be performed. Plasma Zn concentrations were determined after 0.5 mL plasma was deproteinated with 1 mL 10% trichloracetic acid. After centrifuging at 2,500 x g for 10 min, the supernate was read on a flame absorption spectrophotometer (Varian SpectrAA-30) for Zn determination.

Feces and Urine Analysis
In Exp. 3, feces and urine were collected twice every 24-h period at meal times (0700 and 1600). Feces from each 24-h period were combined, mixed thoroughly, weighed, sealed in plastic bags, and stored in a freezer at -18°C. Urine from each 24-h period was combined, mixed thoroughly, strained, its volume was measured, sampled (10 to 30% aliquot), and stored at -18°C in 1-L polypropylene bottles. Chromic oxide (0.05 %) was used as a nondigestible indicator. Hydrochloric acid (6 N) was used as a preservative in the urine. Fecal samples were dried in a mechanical convection oven (GCA Corp., Chicago, IL, Model 845) at 55°C for 24 h and ground in a stainless steel Wiley Mill. Urine samples were prepared for mineral analysis by deproteination with 10% trichloroacetic acid. Fecal samples were prepared for mineral analysis by the nitric-perchloric acid wet digestion procedure as used for tissues. Zinc concentration of feces and urine was determined by flame absorption spectrophotometry.

Tissue Analysis
On d 15 of Exp. 3, all 15 pigs were killed using a lethal injection of pentobarbital sodium (390 mg/mL at 1 mL/4.5 kg of BW) into the jugular vein to obtain liver and kidney tissues. The whole organs were immediately weighed and placed in bags on ice. Tissue samples (approximately 1 g) were prepared for mineral analysis by nitric-perchloric acid wet digestion (Carlson et al., 1999) using 3 mL of 10 M perchloric acid and 20 mL of 10 M nitric acid. Zinc concentrations were determined by flame absorption spectrophotometry.

Zinc Determination
All zinc analyses were determined using glassware that had been washed in 30% nitric acid and rinsed with deionized distilled water. Bovine liver standard (1577b; National Institute of Standards and Technology (NIST), Gaithersburg, MD) was used to establish accuracy of instrument analysis. Variation was accepted within the specified limits of NIST. Zinc concentrations were calculated using exogenous calibration curves.

Statistical Analysis
Data for all experiments were analyzed as a randomized complete-block design using appropriate General Linear Model procedures of SAS (SAS Inst. Inc., Cary, NC). In Exp. 1 and 2, pen was the experimental unit used for analysis of both growth performance and plasma Zn. In Exp. 3, pig was the experimental unit for analysis of plasma, liver, kidney, fecal, and urinary Zn concentration. The mean differences between treatments were tested by comparison of least significance difference.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 Implications
 Literature Cited
 
Growth Performance
In Exp. 1, from d 8 to 28 and overall, ADG was affected by dietary Zn treatments (Table 2Go). Over the 28-d period, pigs fed either 500 ppm additional Zn as SQM-Zn or 3,000 ppm added Zn as ZnO had greater ADG (P < 0.05) than pigs receiving 150 ppm added Zn as ZnO, 500 ppm added Zn as ZnO, or 500 ppm added Zn as Availa-Zn 100. Overall, no difference (P >= 0.05) was observed in ADG among pigs fed 150 or 500 ppm added Zn as ZnO or 500 ppm added Zn as Availa-Zn 100. On d 28, pigs fed 500 ppm added Zn as SQM-Zn or 3,000 ppm added Zn as ZnO averaged 2.7 kg heavier than pigs fed 150 or 500 ppm added Zn as ZnO and 500 ppm added Zn as Availa-Zn 100. During d 15 to 28 (Phase 2), ADFI differed among dietary treatments (P = 0.03); pigs fed 500 ppm added Zn as SQM-Zn or 3,000 ppm added Zn as ZnO had greater ADFI (P < 0.05) than pigs fed 150 ppm added Zn as ZnO or 500 ppm added Zn as Availa-Zn 100. Over the 28-d period, ADFI was not affected (P > 0.05) by dietary Zn treatments. At no time during the 28-d study did dietary Zn affect the feed efficiency (gain/feed) of these nursery pigs under these experimental conditions (P >= 0.09).


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  		Table 2. Effect of different forms and concentrations of additional zinc on growth performance of nursery pigs (Exp. 1)
 
In Exp. 2, over the 28-d period, pigs fed 3,000 ppm added Zn as ZnO had greater ADG and ADFI than pigs fed any other dietary treatment (Table 3Go). Pigs fed either 150 or 500 ppm added Zn as ZnO or 500 ppm added Zn as Availa-Zn 100 had similar (P >= 0.05) growth performance. Pigs fed 3,000 ppm added Zn as ZnO were 2.05 kg heavier than pigs fed any of the other four dietary treatments at the end of the 28-d experiment. Feed efficiency was only affected by dietary Zn treatment during wk 2 of Phase 1 (d 8 to 14). Pigs fed 500 ppm added Zn as Availa-Zn 100 had lower gain/feed (P < 0.05) than those fed the other four dietary Zn treatments.


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  		Table 3. Effect of different forms and concentrations of additional zinc on growth performance of nursery pigs (Exp. 2)
 
In Exp. 3, over the 15-d period, pigs fed either 3,000 ppm added Zn as ZnO or 500 ppm added Zn as SQM-Zn had greater ADG (P < 0.05) than pigs receiving 150 ppm or 500 ppm added Zn as ZnO or 500 ppm added Zn as Availa-Zn 100 (Table 4Go). Pigs fed 150 ppm added Zn as ZnO had lower ADFI (P < 0.05) than those fed the other four dietary Zn treatments. However, during the 5-d collection period, pigs fed 3,000 ppm added Zn as ZnO had greater ADFI (P < 0.05) than pigs fed 150 ppm or 500 ppm added Zn as ZnO or 500 ppm added Zn as Availa-Zn 100. Pigs fed 500 ppm added Zn as SQM-Zn had ADFI similar to that of pigs on all other dietary Zn treatments. Over the 15-d period, feed efficiency (gain/feed) was not affected by dietary Zn treatments (P >= 0.05).


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  		Table 4. Effect of Zn source and concentration on growth performance, tissue Zn concentration, and daily Zn excretion in feces and urine in Exp. 3
 
Blood Characteristics
Table 5Go shows plasma Zn concentrations of pigs. In Exp. 1 (d 14), pigs fed 3,000 ppm added Zn as ZnO had the highest plasma Zn concentrations (P < 0.05), followed by pigs fed 500 ppm added Zn as SQM-Zn, which had greater (P < 0.05) plasma Zn concentrations than pigs fed 150 ppm added Zn as ZnO, but they had concentrations similar (P >= 0.05) to those of pigs fed 500 ppm added Zn as ZnO or 500 ppm added Zn as Availa-Zn 100. In Exp. 2, pigs fed dietary Zn treatments had similar (P >= 0.05) plasma Zn concentrations on d 7. On d 28, pigs fed 3,000 ppm added Zn as ZnO had greater (P < 0.05) plasma Zn concentrations than pigs on any other dietary Zn treatment. On d 15 of Exp. 3, plasma Zn concentration did not differ (P = 0.06) among dietary treatments.


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  		Table 5. Effect of different sources and concentrations of additional Zn on plasma Zn concentration (mg/L) in Exp. 1, 2 and 3
 
Liver and Kidney Characteristics
The effect of dietary treatment on organ Zn concentrations is shown in Table 4Go. Pigs fed 3,000 ppm added Zn as ZnO had greater (P < 0.05) liver Zn concentrations than pigs on all other dietary Zn treatments. Pigs fed 3,000 ppm added Zn as ZnO had renal Zn concentrations which were similar to those of pigs fed 500 ppm added Zn as Availa-Zn 100 but were greater (P < 0.05) than those of pigs fed 150 or 500 ppm added Zn as ZnO or 500 ppm added Zn as SQM-Zn.

Feces and Urine Characteristics
Daily fecal and urinary Zn excretions of pigs in Exp. 3 are shown in Table 4Go. Fecal volume was not different between dietary Zn treatments (P >= 0.05), and the average fecal volume was 8 ± 0.2 g DM/d. Dietary treatment affected (P < 0.05) urinary volume. Pigs fed 3,000 ppm added Zn as ZnO had the greatest (P >= 0.05) volume per day of urine, with 179 mL/d excreted. The lowest urinary volume was seen in pigs fed 150 ppm added Zn as ZnO (99 mL/d), with 500 ppm added Zn as ZnO, Availa-Zn 100, or SQM-Zn being intermediate (110, 133, or 150 mL/d, respectively). Pigs fed 150 ppm added Zn as ZnO excreted less (P < 0.05) Zn in the feces than pigs fed any other dietary treatment. Pigs fed 500 ppm added Zn as ZnO, Availa-Zn 100, or SQM-Zn had similar (P >= 0.05) amounts of fecal Zn excreted. However, pigs fed 3,000 ppm added Zn as ZnO excreted almost four times as much fecal Zn as those pigs fed 500 ppm added Zn as ZnO, Availa-Zn 100, or SQM-Zn (P < 0.05). The greatest urine Zn excretion was observed in pigs fed 3,000 ppm added Zn as ZnO (P < 0.05); all other dietary treatments were similar (P >= 0.05).

Zinc Balance
Zinc balance was calculated using actual daily Zn intake minus daily urine and fecal Zn excretion and is shown in Figure 1Go. The Zn balance of pigs was negative for all dietary treatments, meaning more Zn was excreted than ingested, after receiving the respective dietary treatments for 15 d. Pigs fed 150 ppm added Zn as ZnO were in the least negative balance, but were similar to pigs fed 500 ppm added Zn as ZnO, Availa-Zn 100, or SQM-Zn (P > 0.05). Pigs fed 3,000 ppm added Zn as ZnO showed the most negative Zn balance (P < 0.05) compared with pigs fed the other four dietary Zn treatments.



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  		Figure 1. Effect of Zn source on Zn balance, (Zn intake - [fecal Zn + urinary Zn]), of nursery pigs. a,bMeans in the same row lacking a common superscript differ (P < 0.05).

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
Implications
 Literature Cited
 
These results support the findings of Hahn and Baker (1993), Hill et al. (2000), and Carlson et al. (1999) that feeding pharmacological concentrations of Zn (3,000 ppm added Zn as ZnO) enhances growth rate of nursery pigs. In Exp. 1, ADG was affected by dietary Zn treatment; however, there was no overall change in ADFI or gain/feed of the nursery pigs. Poulsen (1995) and Smith et al. (1997) reported similar findings with a range of 10 to 26% increase in growth rate when nursery pigs were fed pharmacological (2,500 to 4,000 ppm) concentrations of Zn with either no or small improvements in feed intake. In contrast, ADG and ADFI were improved by feeding 3,000 ppm added Zn as ZnO in Exp. 2. Feed intake in Exp. 2 was improved 17% by feeding 3,000 ppm added Zn as ZnO, which is similar to the 14% improvement observed by Hahn and Baker (1993). Ward et al. (1996) and Hoover et al. (1997b) reported that the beneficial effect on growth from supplementation of high concentrations of ZnO could also be achieved by feeding lower concentrations of organic Zn along with a basal amount (250 or 160 ppm) of inorganic Zn as ZnSO4. In agreement with those findings, pigs fed 500 ppm added Zn as SQM-Zn with a basal concentration of 100 ppm inorganic Zn as ZnSO4 in Exp. 1 and Exp. 3 of our study had growth rate similar to those of pigs receiving 3,000 ppm added Zn as ZnO.

The differences observed between Exp. 1 and 2 may be due to environmental variations. In Exp. 2, the building was a more modern nursery building with woven-wire flooring over a shallow flush system. The pigs in Exp. 1 were housed in an older grower building, with concrete-slatted flooring over a pit. Those pigs possibly were stressed or more environmentally challenged with increased disease exposure due to the concrete flooring over a pit. Another possible cause of the inconsistent results seen between the two experiments may be due to the variations in weaning weights and ages of the pigs. The pigs in Exp. 1 had an average weaning weight of 6.45 ± 0.17 kg and an average age of 24 ± 0.5 d, whereas the pigs in Exp. 2 had an average weaning weight of only 5.47 ± 0.01 kg and average age of 18 d of age, indicating variations in health status or length of exposure to disease transmission from the sow.

Results of Exp. 3 show that after the 10-d adjustment period, pigs fed 3,000 ppm added Zn as ZnO were in a negative Zn balance, indicating that the pigs were excreting more Zn than they were consuming on a daily basis (Figure 1Go). Urine Zn concentrations increased as a greater amount of Zn was supplemented in the diet. Pigs fed 3,000 ppm added Zn as ZnO excreted 2.68 mg Zn/d in urine and 2,157 mg Zn/d in feces, which is in agreement with results reported by Hoover et al. (1997a), who fed 3,000 ppm added Zn as ZnO for 14 d prior to collection. Pigs fed 500 ppm added Zn as ZnO, Availa-Zn 100, or SQM-Zn excreted an average of 500 mg Zn/d of Zn in the feces. Therefore, dietary concentrations of Zn fed to nursery pigs above 500 ppm from inorganic or organic sources of Zn results in excess Zn excreted in feces.

Although plasma concentrations and tissue storage are not the same as bioavailability, there were differences in plasma and tissue Zn concentrations between dietary treatments in the present study. Pigs fed 3,000 ppm added Zn as ZnO had the highest plasma Zn concentrations on d 14 in Exp. 1 and d 28 in Exp. 2 compared to the other four dietary treatments. However, mean plasma Zn concentrations of all pigs, independent of dietary treatment, remained within the normal range (0.5 to 1.5 mg/L). In Exp. 3, plasma Zn concentrations exceeded this normal range, possibly due to a change in bleeding time (p.m. vs a.m.) and to the fact that the pigs were individually fed a slightly higher ADFI and Zn intake. Hepatic Zn concentrations were highest for pigs fed 3,000 ppm added Zn as ZnO, with an average Zn concentration of 3,019 ppm. Renal Zn concentrations were highest for pigs fed 3,000 ppm added Zn as ZnO (79 ppm), and pigs fed 500 ppm added Zn as Availa-Zn 100 had similar concentrations (72 ppm). It has been reported that Zn absorption is affected by Zn status and that as dietary Zn increases absorption decreases in pigs (Wang et al., 1993). Although not evaluated in this experiment, it is likely that the amount of endogenously secreted Zn from gastrointestinal secretions may also increase.

It has become routine in the swine industry to add high concentrations (2,000 to 3,000 ppm) of inorganic Zn to nursery diets as a growth promotant. However, the biological mechanism behind the enhanced growth performance is unknown. Carlson et al. (1998) reported that feeding pharmacological concentrations of Zn (3,000 ppm Zn as ZnO) produced deeper crypts and greater total thickness in the duodenum and increased intestinal metallothionein concentrations, which indicates that high amounts of Zn have an enteric effect on the nursery pig. Katouli et al. (1999) reported that 2,500 ppm Zn from ZnO supplemented in the weaned pig diets is beneficial for maintaining the stability of the intestinal microflora and the diversity of the coliforms only during the first 2 wk after weaning. However, Mavromichalis et al. (2000) found that neither high (93%) nor low (39%) bioavailable ZnO affects intestinal morphology of weaned pigs.

It has also been speculated that Zn enhances growth through a systemic effect within the body (via the blood) rather than an enteric effect in the intestinal tract. In this case, organic sources would be more effective than inorganic sources due to higher bioavailability. Wedekind et al. (1994) reported that neither inorganic Zn as ZnO nor organic Zn as Zn methionine or Zn lysine (amino acid complexes) provided more bioavailable Zn than ZnSO4 when three different concentrations of each source were fed to 25- to 90-kg pigs. Mavromichalis et al. (2000) observed that feeding ZnO sources with either high (93%) or low (39%) bioavailabilities did not affect the growth rate in nursery pigs during a 21-d study. In the present study, growth rate was improved under certain nursery conditions by feeding 500 ppm added Zn as SQM-Zn, but pigs fed an additional 500 ppm of either organic (SQM-Zn and Availa-Zn 100) or inorganic (ZnO) Zn source had similar plasma, tissue, urine, and fecal Zn concentrations. These studies demonstrate that bioavailability is irrelevant to the efficacy of growth performance of nursery pigs fed high concentrations of Zn. Further research is needed to determine the specific mode of action and metabolic change through which high dietary concentrations of Zn from either organic or inorganic sources affect growth performance of nursery pigs.


   Implications
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Implications
Literature Cited
 
These data indicate that feeding 3,000 ppm added Zn as ZnO improves growth performance of nursery pigs during the first 4 wk after weaning. However, under certain weaning conditions, growth promotant effects may be observed when supplementing 500 ppm of an organic Zn source as SQM-Zn. The plasma, tissue, urine, and fecal Zn concentrations of pigs fed 500 ppm added Zn as either organic (SQM-Zn and Availa-Zn 100) or inorganic (ZnO) sources were similar, which indicates that Zn bioavailability is not different. Supplementing nursery pigs’ diets with inorganic ZnO above 3,000 ppm added Zn results in excess fecal Zn excretion. The amount of Zn excreted is reflective of dietary concentration and is independent of source. Hence, it is beneficial for producers to feed lower concentrations of zinc independent of source to reduce the amount of zinc being excreted in the feces. However, feeding 2,000 to 3,000 ppm Zn as ZnO appears to be the most efficient in stimulating postweaning growth performance.


   Footnotes
 
1 Contribution from the Missouri Agric. Exp. Stn. Journal series no. 13,139. Back

Received for publication May 21, 2001. Accepted for publication January 18, 2002.


   Literature Cited
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Implications
 Literature Cited
 


Carlson, M. S., G. M. Hill, and J. E. Link. 1999. Early and traditionally weaned nursery pigs benefit from phase-feeding pharmacological concentrations of zinc oxide: Effect on metallothionein and mineral concentrations. J. Anim. Sci. 77:1199–1207.[Abstract/Free Full Text]

Carlson, M. S., S. L. Hoover, G. M. Hill, J. E. Link, and J. R. Turk. 1998. Effect of pharmacological zinc on intestinal metallothionein concentration and morphology in the nursery pig. J. Anim. Sci. 76(Suppl. 1):57 (Abstr.).

Hahn, J. D., and D. H. Baker. 1993. Growth and plasma zinc responses of young pigs fed pharmacologic levels of zinc. J. Anim. Sci. 71:3020–3024.[Abstract]

Hill, G. M., G. L. Cromwell, T. D. Crenshaw, C.R. Dove, R. C. Ewan, D. A. Knabe, A. J. Lewis, G. W. Libal, D. C. Mahan, G. C. Shurson, L. L. Southern, and T. L. Veum. 2000. Growth promotion effects and plasma changes from feeding high dietary concentrations of zinc and copper to weanling pigs (regional study). J. Anim. Sci. 78:1010–1016.[Abstract/Free Full Text]

Hoover, S. L., M. S. Carlson, G. M. Hill, J. E. Link, T. L. Ward, and T. M. Fakler. 1997a. Evaluation of excretion and retention of zinc from inorganic and organic sources in diets fed to weanling pigs. J. Anim. Sci. 75 (Suppl. 1):189 (Abstr.).

Hoover, S. L., T. L. Ward, G. M. Hill, and T. M. Fakler. 1997b. Effect of dietary zinc and copper amino acid complexes on growth performance of starter pigs. J. Anim. Sci. 75 (Suppl. 1):188 (Abstr.).

Katouli, M., L. Meliin, M. Jensen-Waern, P. Wallgren, and R. Mollby. 1999. The effect of zinc oxide supplementation on the stability of the intestinal flora with special reference to composition of coliforms in weaned pigs. J. Appl. Microbiol. 87:564–573.[Medline]

Mavromichalis, I. C. M. P., T. M. Parr, D. Ganessunker, and D. H. Baker. 2000. Growth-promoting efficacy in young pigs of two sources of zinc oxide having either a high or a low bioavailability of zinc. J. Anim. Sci. 78:2896–2902.[Abstract/Free Full Text]

NRC. 1998. Nutrient Requirements of Swine. (10th ed. National Academy Press, Washington, DC.

Poulsen, H. D. 1995. Zinc oxide for weanling piglets. Acta Agric. Scand. Sect. A Anim. Sci. 45:159–167.

Poulsen, H. D. 1998. Zinc and copper as feed additives, growth factors or unwanted environmental factors. J. Anim. Feed Sci. 7:135–142.

Smith, J. W., II, M. D. Tokach, R. D. Goodband, J. L. Nelssen, and B. T. Richert. 1997. Effects of the interrelationship between zinc oxide and copper sulfate on growth performance of early-weaned pigs. J. Anim. Sci. 75:1861–1866.[Abstract/Free Full Text]

Wang, Z. S., A. Atkinson, R. F. P. Bertolo, S. Polberger, and B. Lonnerdal. 1993. Alterations in intestinal uptake and compartmentalization of zinc in response to short-term dexamethasone therapy or excess dietary zinc in piglets. Pediatr. Res. 33:118–124.[Medline]

Ward T. L., G. A. Asche, G. F. Louis, and D. S. Pollmann. 1996. Zinc-methionine improves growth performance of starter pigs. J. Anim. Sci. 74(Suppl. 1):303 (Abstr.).

Wedekind, K. J., A. J. Lewis, M. A. Giesemann, and P. S. Miller. 1994. Bioavailability of zinc from inorganic and organic sources for pigs fed corn-soybean meal diets. J. Anim. Sci. 72:2681–2689.[Abstract]


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Comparison of growth performance and zinc absorption, retention, and excretion in weanling pigs fed diets supplemented with zinc-polysaccharide or zinc oxide
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G. R. Hollis, S. D. Carter, T. R. Cline, T. D. Crenshaw, G. L. Cromwell, G. M. Hill, S. W. Kim, A. J. Lewis, D. C. Mahan, P. S. Miller, et al.
Effects of replacing pharmacological levels of dietary zinc oxide with lower dietary levels of various organic zinc sources for weanling pigs
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O. Hojberg, N. Canibe, H. D. Poulsen, M. S. Hedemann, and B. B. Jensen
Influence of Dietary Zinc Oxide and Copper Sulfate on the Gastrointestinal Ecosystem in Newly Weaned Piglets
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S. B. Williams, L. L. Southern, and T. D. Bidner
Effects of supplemental dietary phytase and pharmacological concentrations of zinc on growth performance and tissue zinc concentrations of weanling pigs
J Anim Sci, February 1, 2005; 83(2): 386 - 392.
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N. R. Augspurger, J. D. Spencer, D. M. Webel, and D. H. Baker
Pharmacological zinc levels reduce the phosphorus-releasing efficacy of phytase in young pigs and chickens
J Anim Sci, June 1, 2004; 82(6): 1732 - 1739.
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M. S. Carlson, C. A. Boren, C. Wu, C. E. Huntington, D. W. Bollinger, and T. L. Veum
Evaluation of various inclusion rates of organic zinc either as polysaccharide or proteinate complex on the growth performance, plasma, and excretion of nursery pigs
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[Abstract] [Full Text] [PDF]

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E. van Heugten, J. W. Spears, E. B. Kegley, J. D. Ward, and M. A. Qureshi
Effects of organic forms of zinc on growth performance, tissue zinc distribution, and immune response of weanling pigs
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