Influence of Supplemental Ascorbic Acid on Broiler Performance Following Exposure to High Environmental Temperature1,2

METABOLISM AND NUTRITION Influence of Supplemental Ascorbic Acid on Broiler Performance Following Exposure to High Environmental Temperature1'2 S. L. PARDUE,3 J. PAUL THAXTON, and JOHN BRAKE Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27695-7608 (Received for publication May 21, 1984)

1985 Poultry Science 64:1334-1338 INTRODUCTION

Ascorbic acid (AA) has been accepted as a nonessential dietary ingredient of poultry diets since the 1920's. Early work showed that chicks, maintained on AA-free diets that were otherwise nutritionally adequate, displayed no adverse effects in growth, production, and livability (Shorten and Ray, 1921; Emmett and Peacock, 1922, 1923; Mitchell et al., 1923; Plimmer and Rosedale, 1923). Mitchell et al. (1923) and Sifri et al. (1977) did not evidence growth stimulation when AA was added to the diets. However, growth stimulation was reported when AA was added to highly purified diets (Briggs et al, 1944), nutritionally deficient diets (Dietrich et al., 1949; March and Biely, 1953), and traditional corn/soy-based rations of turkeys (Dorr and Balloun, 1976) and chicks (Schmeling and Nockels, 1978). These reports suggest that conditions occur

such that endogenous AA synthesis is inadequate and that during these conditions supplemental AA can be efficacious. Supplemental AA also has been reported to improve heat resistance and reduce mortality associated with elevated ambient temperatures in chickens (Thornton, 1962; Perek and Kendler, 1962, 1963; Ahmad et al, 1967; Lyle and Moreng, 1968; Attia, 1976; Pardue et al, 1984). Thornton (1961) and Perek and Kendler (1963) speculated that AA synthesis in the chicken is reduced during periods of high environmental temperature. The present study was conducted to determine if AA supplementation of conventional diets would stimulate growth and improve performance of male and female broilers following exposure to acute episodes of high environmental temperature.

MATERIALS AND METHODS

1 Paper No. 9280 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695. 2 The use of trade names in this publication does not constitute endorsement of products named nor those not mentioned by the North Carolina Agricultural Research Service. 3 Department of Veterinary and Animal Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003.

This study was conducted in a conventional, curtain-sided house with pine shavings serving as litter. The house is oriented in an east/west direction, 16 pens are located in each end, and the ends are separated by a feed/storage room. Each pen was provided initially with a gas-fired brooder and plastic feeder trays. Brooding heat was provided for the first 9 days and feeder trays were replaced by two tube-type feeders during the first week. Water was provided in each pen by a single hanging waterer. Feed and

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ABSTRACT The present study was conducted to determine if dietary ascorbic acid (AA) would improve growth, feed efficiency, and livability of broilers following an acute heating episode. Supplemental AA was provided in the diets at calculated levels of 0, 250, 500, and 1000 ppm, continuously. Females that received 1000 ppm exhibited significantly greater body weights at 2 and 4 weeks of age. No significant effects due to AA supplementation were observed in body weights of males. At 4 weeks of age, chicks were heated on two consecutive days by increasing the ambient temperature (38.3 C at bird level) in the production facility. Heating significantly reduced body weights in males, but not females, at 5 and 7 weeks of age. Feed conversions were increased after heating, but significant effects due to AA were not found. Ascorbic acid did not improve overall livability significantly in either sex, but heat-associated mortality was reduced in supplemented females. (Key words: ascorbic acid, heat, broiler production)

ASCORBIC ACID, BROILERS AND HEATING

RESULTS AND DISCUSSION

During the study, mean house temperatures fluctuated from highs of 29.2 ± .3 and 29.0 ± .3 C in the east and west ends, respectively, except

during periods of heating. Maximum temperature in the west end during heating was 35.6 C and floor temperature reached 38.3 C. Peak temperature in the east end reached 28.9 C during the same period. Mean body weights are presented in Table 2. Females that received 1000 ppm of AA achieved significantly greater body weights at 2 and 4 weeks of age and numerically greater body weights at 5 and 7 weeks of age than chicks fed 0 ppm AA. Heating did not affect mean body weights of females significantly, and mean body weights of males were not affected significantly by heating or AA supplementation.

TABLE 1. Composition of basal diets Content Ingredient

Starter (0-2) 1

Grower Finisher (3-6) (7)

— (%) Ground corn 61.45 30.30 Soybean meal (48%) 3.20 Meat meal (58%) 2.40 Fat 2 1.50 Defluorinated phosphate (18% P, 32% Ca) .30 Limestone .30 DL-Methionine .20 Choline chloride (50%) .10 Mineral premix 3 .10 Vitamin premix" 5 .10 Coccidiostat .05 Sodium chloride

64.62 28.40 1.50 2.90 1.40

76.30 15.35 6.60 .10 .43

.30 .29 .20 .10 .10 .10 .09

.55 .10 .20 .10 .10 .17

20.30

18.00

Calculated analysis: kcal/kg Protein, %

22.00

'Weeks fed. 2

Fat contained .05% Tenox 26 as a preservative. Tenox 26 (Eastman Chemical Products, Inc., Kingsport, TN) is a mixture of 6% tertiary-butyl-hydroquinone, 10% butylated hydroxyanisol, 10% butylated hydroxy toluene, 6% citric acid,and 68% carrier. 'Mineral premix supplied (mg/kg) in diet: manganese, 150; zinc, 100; iron, 50; copper, 6; iodine, 2. 4 Vitamin premix supplied (kg) of diet: Vitamin A, 13,216 IU; vitamin D 3 , 6,608 IU; vitamin E, 13.2 IU; riboflavin, 17.6 mg; vitamin B 1 2 , 26 Mg; pyridoxine hydrochloride, 2.7 mg; d-biotin, 22 Mg; menadione sodium bisulfite, 12.3 mg; folic acid, .55 mg; thiamine mononitrate, 2.4 mg; niacin, 66 mg; dpantothenic acid, 22 mg; selenium, 20 Mg- The vitamin premix contained 11.02% Tenox 26 as a preservative. 5

Coban (Elanco Products Co., Indianapolis, IN).

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water were available ad libitum. A 23:1 lightdark photoperiod was used throughout the study. Nineteen hundred-twenty broiler chicks (Ross x Arbor Acres) were used in this study. The experiment was conducted between late May and July. All chicks were sexed, debeaked, and vaccinated against Marek's disease at hatching. Sixty chicks were assigned at random to each of 32 floor pens, which measured 3.81 x 1.22 m; therefore, density was .077 m 2 /bird. Equal numbers of each sex were allotted to each pen and females were toe-clipped to facilitate differentiation of the sexes. A 4 X 2 factorial arrangement was employed with four levels (0, 250, 500, and 1000 ppm) of AA and heating vs. nonheating as main effects. Concentrations of AA were established by thoroughly mixing weighed amounts of AA (Lascorbic acid, coated, Hoffmann-LaRoche, Inc., Nutley, NJ) to the basal starter, grower, and finisher diets (Table 1). This particular form of AA was chemically stabilized to retard oxidation and mash feeds were employed to limit AA breakdown associated with pelleting. Chicks in the west end of the house were designated to be heated and those in the east end served as nonheated controls. At 4 weeks of age, on 2 consecutive days beginning at 0900 hr and ending at 1700 hr, chicks were heated by firing the brooders and partially raising the curtains (see Results and Discussion for temperature regimens). A total of eight treatments with four replicates of each treatment were investigated. Mean body weights were determined for each sex and treatment at 2, 4, 5, and 7 weeks of age. Mortality was monitored daily. Feed conversions were determined/pen at 2, 4, 5, and 7 weeks of age and were not adjusted within time for mortality. All data were compared by the general linear models procedure of the Statistical Analysis System (SAS, Barr et al., 1979). Means were separated by Duncan's new multiple range test. Data concerning percent livability were converted to the appropriate arscine transformations prior to analyses. Statements of significance are based on P«.05 unless otherwise indicated.

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133d

P A R D U E ET A L .

T A B L E 2 . M?a» borfy weight

(g) as infl uenced

by supplemental

ascorbtic acid and hea ting'

Ascorb:ic acid

250 ppm

Sex

2

Female Male

245 ± 281 ±

4

Female Male

739± 9a 866 ± 14a

739 ± 9 a 839 ± 14a

5

Female Male

1039±23a 1225 ± 1 8 a

1052 ± 3 2 a 1220 ± 2 7 a

7

Female Male

1506 ± 1 8 a 1810± 23a

1533 ± 1 8 a 1833 ± 2 3 a

a

Oppm 5a 6a

249 ± 272 ±

1000 ppm

500 p p m 6a 7a

4b 4a

N o heat

Heat 4X 5X

5X 6X

249 ± 7 a 263 ± 1 2 a

268 ± 281 ±

757 ± 9 a b 839 ± 2 7 a

776 + 9 b 875 ± 1 4 a

753 ± 8 X 857 ± l l x

753 ± 8 X 852 + 1 4 x

1048 ± 1 8 a 1197 ± 3 2 a

1066 ± 1 4 a 1229 ± 9 a

1052 ± 1 3 x 1225 ± 1 6 x

1048 ± 1 7 x 1207± 15x

1533 ± 2 3 a 1796 ± 2 7 a

1538 ± 1 8 a 1833 + 1 8 a

1533 ± 1 3 x 1819 ± 1 6 x

1524± 12x 1814 ± 1 5 x

254 ± 277 ±

249 ± 272 ±

' ' ^ M e a n s in a row for each main effect possessing different superscripts differ significantly at P<.05.

1

Each main effect mean is accompanied by its SEM.

Possibly the improvement in the growth of females was due to immaturity of the endogenous AA enzyme system, as many enzyme systems in neonates function suboptimally. Therefore, supplementation provided sufficient AA for metabolism, which otherwise may have been lacking. The failure of supplemental AA to improve body weight gains following heating has been reported previously (Subaschandran and Balloun, 1967). However, in another study with chicks reared in environmentally-regulated rooms and subjected to a heating regimen that differed from that of the present study, we found significantly greater rates of gain following heating of chicks supplemented with 1000 ppm of AA (Pardue et al, 1984). Feed efficiency, as measured by feed conversion (kilogram feed consumed/kilogram body weight gained) was decreased (P<.01) by heating from 4 to 5 weeks of age (Table 3). Significant effects on feed conversion, however,

were not found at any other time by either treatment. The effects of AA supplementation and heating on livability are presented in Table 4. In females, neither AA supplementation nor heating influenced livability significantly. Supplementation with AA in males also had no significant effect on livability. Heating reduced (P«.01) livability in males at 5 and 7 weeks of age. Mortality in males due to heating was increased 5.9 and 6.7% over nonheated chicks at 5 and 7 weeks of age, respectively. The increased susceptibility of males, relative to females, to the lethal effects of high environmental temperature is in agreement with Reece et al. (1972). The physiologic basis for this sex-associated variation in susceptibility of juvenile chicks is ill-defined and warrants additional study; however, the greater surface area to mass ratio of females may contribute to the enhanced heat resistance observed

TABLE 3. Feed conversion (kilograms feed consumed per body weight gained) as influenced by supplemental ascorbic acid and heating (4 to 5 weeks)1 Ascorbic acid

No heat Heat X

0 ppm

250 ppm

500 ppm

1000 ppm

X

2 . 1 4 ± .03 2.54 ± .14 2.34A

2.18 ± .06 2.66 ± .11 2.42A

2 . 1 8 ± .05 2.30 ± .16 2.24^

2.19 ± .03 2.39 ± .10 2.29A

2.17^ 2.47B

A,B Main effect means possessing different superscripts differ significantly at P<.01. 1

Each interactive mean is accompanied by its SEM.

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Week

ASCORBIC ACID, BROILERS AND HEATING

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TABLE 4. Livability (%) as influenced by supplemental ascorbic acid and heating1 Ascorbic acid Week

Sex

Oppm

2

Female Male

97.9 ± 97.5 ±

4

Female Male

96.3 + 97.1 ±

5 7

500 p p m

1000 p p m

.9a .5a

96.7 ± 1.4 a 97.9 ± 1.7 a

94.2 ± 2 . 3 a 95.4 ± 1.8 a

97.9 ± 99.2 +

.8a .8a

94.2 ± 1.0 a 97.5 ± 1.6 a

Female Male

94.6 ± 1.3 a 9 4 . 2 ± 1.9 a

Female Male

93.3 ± 1.4 a 92.9 ± 2 . 3 a

No h e a t

Heat

.9a .8a

9 6 . 7 + 1.4 X 97.9 ± 7 X

96.7 ± . 7 X 97.1 ± l . l x

92.9 ± 2 . 8 a 93.8 ± 2 . 0 a

97.1 ± 1.6 a 97.5 ± 1.0 a

95.2 ± 1 5 X 96.9 ± 9 X

95.0 ± .9X 9 5 . 8 ± 1.2 X

92.9 ± 1.6 a 93.3 ± 3 . 4 a

92.1 ± 2 . 7 a 9 2 . 5 ± 1.9 a

96.7 + 1.5 a 9 4 . 6 ± 1.3 a

95.0 ± 1 5X 96.5 ± 1 0 X

93.1 ± 1.1 X 9 0 . 8 ± 1.7Y

92.1 ± 1.4 a 90.8 ± 3 . 7 a

90.8 ± 2.9a 90.8 ± 2 . 2 a

9 4 . 2 + 1.5 a 93.3 ± 1.5 a

93.5 ± 1 6 X 95.2 ± 1 l x

9 1 . 7 ± 1.0 X 8 8 . 8 ± 1.9y

' "Means in a row for each main effect possessing different superscripts differ significantly at P<.05. 1

Each main effect mean is accompanied by its SEM.

in this sex. This hypothesis is supported by the findings of Reece et al. (1971) that heavier broilers had increased susceptibility to heat prostration when compared with lighter birds. In this, as well as the present study, males were heavier (P«.01) than females at all times of measurement. Additional sex-associated differences also may influence heat resistance. Schmeling and Nockels (1978) reported significantly lower plasma corticosterone in female, Single Comb White Leghorns when compared to males following adrenocorticotropin administration. Dieter (1969) has shown that androgens can reduce AA synthesis by limiting the activity of gluconate nicotinamide adenine dinucleotide

phosphate oxidoreductase, which then lowers tissue AA concentrations. In both sexes, the main effect of AA on livability was nonsignificant. However, from 4 to 5 weeks of age, i.e., the period when heat-associated mortality occurred, the interaction of AA and heat was highly significant (P«.01) in males and significant in females (Table 5). The females that received 500 and 1000 ppm exhibited a markedly reduced mortality during the postheating period. Males exhibited increased mortality when fed 250 ppm of AA, whereas the birds fed 500 and 1000 ppm AA had reduced heatassociated mortality. In summary, AA supplementation did not significantly improve livability, although heat-

TABLE 5. Change in mortality (%) from Weeks 4 to 5 1 Ascorbic acid 2 5 0 pp m

Treatment

0 ppm

Female* No heat Heat X

.83 2.50 1.67 ±

Male** N o heat Heat X

.83 5.00 2.93 ± 1 . 6 0 A

.90

A

0 2.50 1.25 ±

.87

1 0 0 0 ppm

5 0 0 ppm

A

0 8.33 4.17 ± 2 . 5 8 A

0 1.67 .84 ±

X

.21 ± 1.88 +

0 49A

0 2.50 1.25 ± 1 2 5 A

.83 .42 ±

.42

.2iy .61x

A

.83 4.17 2.50 ± 1 . 2 3 A

.42 ± .28y 5.00 ± 1 . 4 9 x

' '"Means for each main effect within each sex possessing different superscripts differ significantly at P«.01. 1

Each main effect mean is accompanied by its SEM.

•Ascorbic acid X heat interaction is significant at P<.05. **Ascorbic acid X heat interaction is significant at P<.01.

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250 p p m

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PARDUE ET AL.

ACKNOWLEDGMENTS The authors thank Robert Hunter for technical aasistance and Rosalyn Mitchell for secretarial support. Appreciation in extended to Hoffmann-LaRoche, Inc., Nutley, NJ, for providing the ascorbic acid and funding a portion of this work.

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581-599. Emmett, A. D., and G. E. Peacock, 1922. The chick as an experimental animal in vitamin studies. A preliminary report. J. Biol. Chem. 50:xl—xli. Emmett, A. D., and G. E. Peacock, 1923. Does the chick require the fat-soluble vitamins? J. Biol. Chem. 56:679-693. Lyle, G. R., and R. E. Moreng, 1968. Elevated environmental temperature and duration of post exposure ascorbic acid administration. Poultry Sci. 47:410-417. March, B., and J. Biely, 1953. The effect of ascorbic acid on the growth rate of chicks. Poultry Sci. 32:768-774. Mitchell, H. H., F. E. Kendall, and L. E. Card, 1923. The vitamin requirements of growing chickens. Poultry Sci. 2:117-124. Pardue, S. L., J. P. Thaxton, and J. Brake, 1984. Effects of dietary ascorbic acid in chicks exposed to high environmental temperature. J. Appl. Physiol, (in press) Perek, M., and J. Kendler, 1962. Vitamin C supplementation to hens' diets in a hot climate. Poultry Sci. 41:677-678. Perek, M., and J. Kendler, 1963. Ascorbic acid as a dietary supplement for White Leghorn hens under conditions of climatic stress. Br. Poult. Sci. 4:191-200. Plimmer, R.H.A., and J. L. Rosedale, 1923. The rearing of chickens on die intensive system. Part IV. C-vitamin requirements of chickens and other birds. Biochem. J. 17:787-793. Reece, F. N...J. W. Deaton, and L. F. Kubena, 1971. Effects of high temperature and humidity on heat prostration of broiler chickens. Am. Soc. Agric. Eng., Paper No. 71—912. Reece, F. N., J. W. Deaton, and L. F. Kubena, 1972. Effects of high temperature and humidity on heat prostration of broiler chickens. Poultry Sci. 51:2021-2025. Schmeling, S. K., and C. F. Nockels, 1978. Effects of age, sex, and ascorbic acid ingestion on chicken plasma corticosterone levels. Poultry Sci. 57: 527-533. Shorten, J. A., and C. B. Ray, 1921. The antiscorbutic and antiberiberi properties of certain sun-dried vegetables. Biochem. J. 15:274—285. Sifri, M., F. H. Kratzer, and L. C. Norris, 1977. Lack of effect of ascorbic and citric acids on calcium metabolism of chickens. J. Nutr. 107:1484— 1492. Subaschandran, D. V., and S. L. Balloun, 1967. Acetyl-p-aminophenol and vitamin C in heatstressed birds. Poultry Sci. 46:1073-1076. Thornton, P. A., 1961. Increased environmental temperature influences on ascorbic acid activity in the domestic fowl. Fed. Proc. 20:158. Thornton, P. A., 1962. The effect of environmental temperature on body temperature and oxygen uptake by the chicken. Poultry Sci. 4 1 : 1 0 5 3 1060.

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associated mortality was reduced in both sexes that received 500 or 1000 ppm AA. Stimulation of growth by AA in females, but not males, during the early phase of the trial suggests a need to investigate the possible sex differences in AA synthesis, metabolism, and requirement. When the results of this study are compared with those of the literature, it is obvious that inconsistencies and conflicting results exist concerning the essentiality of AA as a required dietary ingredient of poultry. No argument has been made that AA is required if optimum nutrition and management procedures are practiced; however, the present results emphasize that when increased mortality and decreased growth can be attributed to undesirable environmental conditions, AA holds potential to reduce these undesirable effects.