Effect of Antibiotics on Tissue Trace Mineral Concentration and Intestinal Tract Weight of Broiler Chicks1,2

Effect of Antibiotics on Tissue Trace Mineral Concentration and Intestinal Tract Weight of Broiler Chicks 1,2 P. R. HENRY, C. B. AMMERMAN3, D. R. CAMPBELL and R. D. MILES Departments of Animal Science and Poultry Science, University of Florida, Gainesville, Florida 32611 (Received for publication April 14, 1986) ABSTRACT Two experiments were conducted with broiler-type chicks to determine the effect of antibiotics on intestinal weight and kidney, bone, and liver trace mineral concentrations. All antibiotics were in diets at the manufacturers' recommendations. Feed intake of experimental diets (antibiotics or non-treated control) was restricted to 90% of that of an additional group fed the control diet ad libitum. Feed intake, weight gain, and feed efficiency were not affected (P>.10)by dietary treatments. Virginiamycin decreased intestinal weight an average of 19% as compared with 14% for bambermycins and oxytetracycline, 6% for Zn bacitracin, and 18% for lincomycin. Except for Zn bacitracin, all antibiotics produced intestinal weights which were lower (P<.01) than those of controls. Only virginiamycin increased (P<.01) kidney Mn concentration. Bone Mn concentration was greater (P<.01) for virginiamycin than bambermycins or oxytetracycline in Experiment 2, and greater (P<.05) for lincomycin than virginiamycin or Zn bacitracin in Experiment 2. Feeding Zn bacitracin increased (P< .01) bone Zn concentration whereas feeding virginiamycin caused a decline (P<.05) in bone Zn concentration in Experiment 1. There were no differences in Cu, Zn, or Fe concentrations in liver or kidney. (Key words: antibiotics, minerals, intestinal weight, broilers) 1987 Poultry Science 66:1014-1018 INTRODUCTION

Antibiotics differ with regard to their ability to control gastrointestinal microflora and consequently vary with respect to their mode of action (Visek, 1978). Some factors affected by antibiotics that thus contribute to their mode of action in nonruminants include decreasing the rate of passage (Ravindrin et al., 1984), preventing the metabolism of glucose to lactic acid in the crop and small intestine, preventing the degradation of lysine in the small intestine (Lindsey et al., 1985) and decreasing small intestinal mass through a reduction in lamina propria and reticuloendothelial elements (Gordon and Bruckner-Kardoss, 1961). Decrease in intestinal mass is important because the small intestinal mucosa is the most rapidly regenerating tissue in the body (LeBlond and Walker, 1956), especially early in life. Maintenance of a greater

intestinal mass would result in greater utilization of nutrients by the intestinal mucosa. Decreased thickness of intestinal mucosa may also enhance nutrient absorption by the host. Virginiamycin was shown to increase bone ash percentage and improve phosphorus utilization in broilers (Bureshef al., 1985). Manganese absorption and deposition in bone and kidney were also increased by virginiamycin regardless of dietary Mn concentration at 100 or 1,100 mg/kg (Henry et al., 1986). Comparisons among various antibiotics in the same experiment regarding effects on intestinal tract weight and mineral utilization could not be found in the literature. The present experiments were conducted to compare various antibiotics with respect to their ability to increase tissue mineral concentration and decrease intestinal tract weight. MATERIALS AND METHODS

1

Florida Agricultural Experiment Station Journal Series Number 7234. 2 The authors wish to acknowledge International Minerals and Chemical Corp., Mundelein, IL, Moorman Manufacturing Co., Quincy, IL, and Occidential Chemical Agricultural Products, Inc., Tampa, FL for funds in support of this research. 3 To whom reprint requests should be addressed.

Experiment 1. A total of 144 1-day-old male, beak-trimmed Peterson X Arbor Acre chicks was used in a completely randomized design to study the effect of different antibiotics on tissue Mn uptake from conventional corn-soybean meal diets. Ad libitum intake was determined with 4 pens of six birds each fed the basal diet (Table 1). The remaining 120 birds were as-

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ANTIBIOTICS ON TRACE MINERALS AND INTESTINES

signed to four treatments with five pens of six chicks fed one of four treatment diets for 21 days. Dietary treatments were 1) basal or basal supplemented with 2) 10 g/metric ton virginiamycin, 3) 2 g/metric ton bambermycins, or 4) 200 g/metric ton oxytetracycline. All antibiotics were added at the manufacturers' recommended levels. To eliminate the possibility that higher tissue mineral concentration could be attributed to increased dietary mineral intake due to greater feed intake by antibiotic-fed birds, chicks fed the experimental diets were restricted to 90% of the previous day's intake of birds fed ad libitum. Chicks were housed in an electrically heated Petersime battery brooder with raised wire floors and exposed to 24 hr of constant light. At the end of 21 days, experimental birds were weighed and killed. The right tibia, both kidneys, and liver were removed and frozen for analysis of Mn, Cu, Fe and Zn by atomic absorption spectrophotometry (Anonymous, 1982) on a Perkin-Elmer Model 5000 (Norwalk, CT) with AS-50 autosampler. Livers were rinsed in deionized water and blotted dry with ashless filter paper to remove blood and bile prior to

1015

analysis. Reference materials from the National Bureau of Standards were analyzed along with tissue and feed samples. The entire small intestinal tract was removed, opened, and contents removed by careful hand stripping. Empty intestinal tract weights were recorded and weight expressed per 100 g body weight. Data were analyzed by a general linear models procedure (Statistical Analysis System, 1982), and differences among means determined by Duncan's multiple range test. Experiment 2. A total of 144 1-day-old, male Cobb feather-sexed chicks was fed as described previously. Ad libitum intake was determined with four pens of six birds each fed the basal diet (Table 1). Dietary treatments, which were limit-fed at 90% of the ad libitum intake, were 1) basal (Table 1) or basal with 2) 10 g/metric ton virginiamycin, 3) 50 g/metric ton Zn bacitracin, or 4) 4 g/metric ton lincomycin. All procedures were as described for Experiment 1. RESULTS AND DISCUSSION

There was no significant (P>.10) effect of antibiotics on daily feed intake, daily gain, or feed:gain ratio which averaged 32.6, 25.0 and

TABLE 1. Composition of basal diet: Experiments 1 and 2' Experiment Ingredient

1

2

(%) Yellow corn Soybean meal (48.5% crude protein) Corn oil Ground limestone Dicalcium phosphate (18.5% P, 22% Ca) DL-Methionine Iodized salt Microingredients2 Composition 3 Crude protein, % Energy, kcal metabolizable energy/kg Manganese, mg/kg Copper, mg/kg Zinc, mg/kg Iron, mg/kg 1

56.33 37.29 2.50 1.01 1.72 .25 .40 .50 23 3,000 94 13 69 460

23 3,000 87 20 68 391

As-fed basis.

2

Ingredients supplied per kilogram of diet: vitamin A palmitate, 6,600 IU; vitamin D 3 , 2,200 IU; menadione dimethylpyrimidinol bisulfite, 2.2 mg; riboflavin, 4.4 mg; pantothenic acid, 13 mg; niacin, 40 mg; choline chloride, 500 mg; vitamin B , 2 , .022 mg; ethoxyquin, .0125%; Mn, 60 mg; Fe, 50 mg; Cu, 6 mg; Zn, 36 mg. J

Dry matter basis, minerals by analysis, protein and energy calculated.

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HENRY ET AL.

1.31 g/g, respectively in Experiment 1 (Table 2). In Experiment 2, feeding antibiotics also did not influence (P>. 10) chick performance when diets were limit fed (Table 2); however, feed intake amounts were different in the two experiments, possibly because of the strain of chicks used, so data were not combined. All antibiotics decreased (P<.001) intestinal tract weight in Experiment 1, but the response was greatest for virginiamycin (Table 2). In Experiment 2, birds fed virginiamycin and lincomycin had lower (P<.01) intestinal tract weights than those fed Zn bacitracin or control diets (Table 2). In Experiment 2, the intestinal weights of control birds averaged about 15% less than those of birds in Experiment 1 or in an earlier experiment using Cobb birds (Henry et al., 1986). The decrease in intestinal tract weight observed for all antibiotics tested, except for Zn bacitracin in Experiment 2, and especially for virginiamycin and lincomycin, has been reported previously for virginiamycin (Henry et al., 1986). Penicillin and aureomycin have also been shown to decrease intestinal weight in the chick (Pepper^al., 1953; Coates etal., 1955).

The decrease in intestinal mass appeared visually to be due to thinning of the mucosa as shown by Gordon and Bruckner-Kardoss (1958-1959; 1961). Moore et al. (1946) suggested that gastrointestinal bacteria produced toxins. Control of bacteria and thus elimination of toxins would also eliminate the necessity of a thickened intestinal wall to provide protection for the host animal. Dry kidney and liver weights and bone ash weight averaged .789 ± .014, 4.30 ± .092, and .597 ± .007 g, respectively for Experiment 1 and were not affected (P>. 10) by dietary treatment. In Experiment 2, the organs weighed .812 ± .015, 4.40 ± .076, and .668 ± .007 g, respectively and were not affected (P>.10) by antibiotics. Kidney Mn concentration was greater (P<.01) for birds fed virginiamycin than for birds fed other treatments in Experiment 1 (Table 3). Kidney Cu, Zn, and Fe averaged 17 ± .28, 81 ± .64 and 300 ± 4.6 mg/kg and were not affected by treatment. In Experiment 2, chicks fed virginiamycin had greater (P<.01) kidney Mn concentrations than birds fed control or Zn bacitracin diets but not lincomycin diets

TABLE 2. Effect of antibiotics on performance and intestinal tract weight

Treatment

1

Experiment 1 Control Virginiamycin Bambermycins Oxytetracycline Pooled SE 4 Experiment 2 Control Virginiamycin Zn bacitracin Lincomycin Pooled SE

Average daily intake 2

Average daily gain3

Feed conversion2

Intestinal tract weight 3

(g/g)

(g/100 g body weight)

32.7 32.8 32.5 32.6 .08

24.7 25.4 25.1 24.8 .20

1.32 1.29 1.30 1.31 .01

3.34 a 2.55 c 2.87 b 2.86 b .03

37.3 37.3 37.5 37.4 .11

24.9 25.0 25.2 25.0 .17

1.49 1.49 1.49 1.50 .01

2.84 A 2.44 B 2.66 A 2.32 B .02

a c Means in the same column, and within the same experiment, that have different superscripts are significantly different (P<.001).

AR

' Means in the same column, and within the same experiment, that have a different superscript are significantly different (P<.01). 1 All four dietary treatments were fed at 90% of the ad libitum intake established by an additional four pens of birds fed the basal diet. 2

Each value represents the mean of five pens.

3

Each value represents the mean of 30 chicks.

4

SE = Standard error.

ANTIBIOTICS ON TRACE MINERALS AND INTESTINES

(Table 3). Kidney Cu, Zn, and Fe concentrations averaged 24 ± .42, 77 ± .75, and 277 ± 3.8 mg/kg, respectively, and were not affected by treatments. Bone Mn was also greatest (P<.01) for virginiamycin-fed birds (Table 3). Birds fed bambermycins or oxytetracycline had intermediate bone Mn concentrations and control birds were lowest. Bone Zn was lower (P<.05) in virginiamycin-fed birds than in birds in other treatments, and this could not be explained based on dietary intake of the element. Birds fed lincomycin in Experiment 2 had greatest (P<.05) bone Mn concentrations, followed by those fed virginiamycin, Zn bacitracin, and control diets. Bone Zn was greater (P<.01) for birds fed Zn bacitracin than for other birds; however, Zn concentrations were 68, 74, 102, and 65 mg/kg for control, virginiamycin, Zn bacitracin, and lincomycin diets, respectively; Zn intake was greatest for the Zn bacitracin treatment. Bone is the tissue most sensitive to dietary Zn concentrations (Henry et al., 1984). Liver Mn, Cu, Zn, and Fe averaged 8.7 ± .13, 14 ± .24, 59 ± .83, and 240 ± 6.4 mg/kg, respectively, in Experiment 1, and 9.5 ± .13, 14 ± .23, 64

± .80, and 244 ± 6.9 mg/kg, respectively in Experiment 2; trace elements in liver did not differ significantly among treatments. Virginiamycin and lincomycin produced the greatest increases in tissue Mn concentration when compared with other antibiotics and controls. Virginiamycin increased bone and kidney Mn concentration regardless of dietary Mn concentration (100 vs 1,100 mg/kg) in an earlier experiment (Henry et al., 1986). Absorption of Cu, Zn, and Fe as measured by increased tissue uptake, however, was not enhanced by antibiotics. There appears to be a difference among Mn, Cu, Zn, and Fe in the way they are absorbed from the gastrointestinal tract (Underwood, 1977). Copper, Zn, and Fe are bound to protein in the lumen of the intestine and absorbed through the mucosa for storage or transfor to plasma depending on the animal's current status with respect to each element. Manganese is not necessarily bound to protein in the lumen and can be absorbed in an ionic state by the mucosa. Unlike Cu, Zn, and Fe, the mucosa does not act as a storage depot. Instead, the liver exerts greater homeostatic control by regulating biliary excretion of Mn. It appears that the decrease in

TABLE 3. Effect of antibiotics on tissue trace mineral

Treatment

Kidney Mn, dry basis

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composition1

Bone Mn, ash weight basis

Bone Zn, ash weight basis

(mg/kg) Experiment 1 Control Virginiamycin Bambermycins Oxytetracycline Pooled SE 2 Experiment 2 Control Virginiamycin Zn bacitracin Lincomycin Pooled SE

9.0 U

10.1 C 8.1 a 8.6 ab .09

8.6 a 9.6 b 8.5 a 9.3ab .11

5.5 a 8.2C 6.8 b 6.7 b .12

410 D 385A 415B 411B 3.7

6.2 A 7.0 B 6.6'AB 7.7V.13

380a 378a 431 b 383a 3.4

Means within columns in the same experiment with different superscripts are significantly different (P<.01). — Means within columns in the same experiment with different superscripts are significantly different (P<.05). 1

Each value represents the mean of 30 chicks.

2

SE = Standard error.

HENRY ET AL.

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intestinal tract mass, which appeared visually to be the result of thinning of the intestinal wall brought about by feeding antibiotics, enhanced Mn absorption but did not influence absorption of Cu, Zn, or Fe. REFERENCES Anonymous, 1982. Analytical Methods for Atomic Absorption Spectrophotometry. The Perkin-Elmer Corp., Norwalk, CT. Buresh, R. E., R. D. Miles, and R. H. Harms, 1985. Influence of virginiamycin on phosphorus utilization by broiler chicks. Poultry Sci. 64:757-758. Coates, M. E., M. K. Davis, and S. K. Kon, 1955. The effect of antibiotics on the intestine of the chick. Br. J. Nutr. 9:110-119. Gordon, H. A., and E. Bruckner-Kardoss, 1958-1959. The distribution of reticulo-endothelial elements in the intestinal mucosa and submucosa of germ-free, monocontaminated and conventional chickens orally treated with penicillin. Antibiot. Annu. 1012-1019. Gordon, H. A., and E. Bruckner-Kardoss, 1961. Effects of the normal microbial flora on various tissue elements of the small intestine. Acta Anat. 44:210-225. Henry, P. R., C. B. Ammerman, and R. D. Miles, 1984. Tissue uptake of zinc in chicks fed graded levels of zinc sulfate. Poultry Sci. 63(Suppl. 1):115. (Abstr.)

Henry, P. R., C. B. Ammerman, and R. D. Miles, 1986. Influence of virginiamycin and dietary manganese on performance, manganese utilization and intestinal tract weight of broilers. Poultry Sci. 65:321-324. LeBlond, C. P., and B. E. Walker,1956. Renewal of cell populations. Physiol. Rev. 35:255-257. Lindsey, T. O., R. D. Hedde, and J. A. Sokolek, 1985. Characterization of feed additive effects on the gut microflora of chickens. Poultry Sci. 64(Suppl. 1):27— 28. (Abstr.) Moore, P. R., A. Evenson, T. D. Luckey, E. McCoy, C. A. Elvehjem, and E. B. Hart, 1946. Use of sulfasuxidine, streptothricin and streptomycin in nutritional studies with the chick. J. Biol. Chem. 165:437441. Pepper, W. F., S. J. Slinger, and I. Motzok, 1953. Effect of aureomycin on the niacin and manganese requirements of chicks. Poultry Sci. 32:656-660. Ravindrin, V., E. T. Kornegay, and K. E. Webb, Jr., 1984. Effects of fiber and virginiamycin on nutrient absorption, nutrient retention and rate of passage in growing swine. J. Anim. Sci. 59:400-408. Statistical Analysis System, 1982. SAS user's guide. Statistical Analysis System Inst., Inc., Gary, NC. Underwood, E. J., 1977. Trace Elements in Human and Animal Nutrition. 4th ed. Academic Press, New York, NY. Visek, W. J., 1978. The mode of growth promotion by antibiotics. J. Anim. Sci. 46:1447-1469.