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Effect of Acute Heat Stress on Amino Acid Digestibility in Laying Hens - Poultry [Skip to Content]
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Illinois Livestock Trail
FULL TEXT PAPER
Effect of Acute Heat Stress on Amino Acid Digestibility in Laying Hens
by K. W. KOELKEBECK, C. M. PARSONS, and XINCHENG


ABSTRACT

An experiment was conducted to determine the effect of acute heat stress exposure on amino acid digestibility in laying hens. A total of 30 commercial laying hens were singly housed in an environmentally controlled facility, fed a standard laying ration, and exposed to a constant thermoneutral temperature (21 C) for 12 d. The hens were then randomly fed one of three diets (10 hens per diet) and exposed to three concurrent temperature periods (8 d each) which consisted of: 1) a constant 21 C temperature, 2) a cycling temperature of 35 C for 12 h and 29 C for 12 h, and 3) a constant 21 C temperature. The diets were: 1) an 18% CP corn-soybean meal diet, 2) Diet 1 with 15% meat and bone meal, or 3) Diet 1 with 5% alfalfa and 20% wheat bran. Excreta were collected from all hens during the last 4 d of each temperature period and apparent amino acid digestibility was determined.

There was a significant diet effect (P < 0.05) on amino acid digestibility. Digestibility of amino acids in Diet 2 (15% meat and bone meal) was higher (P < 0.05) than in the other two diets. In addition, digestibility of amino acids in Diet 3 (alfalfa and wheat bran) was significantly lower (P < 0.05) than in Diets 1 or 2. Heat stress generally had no significant effect on amino acid digestibility except for Lys digestibility which was higher during the heat stress period compared to the initial thermoneutral period. These results indicated that acute heat stress had no adverse effects on dietary amino acid digestibility in laying hens.

Key words: laying hens, amino acid digestibility, high fiber diet, heat stress, cycling temperature

INTRODUCTION

High environmental temperatures have deleterious effects on growth and production performance of poultry. In broilers, it has been shown that decreased rate of growth occurs (Howlider and Rose, 1987) when environmental temperature rises. In laying hens, heat stress depresses egg production (Marsden et al. 1987) and egg weight (Peguri and Coon, 1991). This negative effect of heat stress on growth rate and production is probably due to reduced feed intake for broilers (Hurwitz et al. 1980) and laying hens (Savory, 1986). When feed intake declines during heat stress, the availability of important nutrients may be reduced. In a recent study by Zuprizal et al. (1993), they found that the true digestibilities of 12 amino acids were generally depressed in two rape seed and two soybean meal diets when fed to broilers subjected to an increasing ambient temperature exposure from 21 to 32 C. In an earlier study, Wallis and Balnave (1984) found that the influence of environmental temperature on amino acid digestibility was sex-related, with high temperatures decreasing digestibility of amino acids in female but not male broilers. The results of these two studies suggest that digestibilities of amino acids may be reduced in broiler chickens during periods of heat stress. To our knowledge, no such research has been conducted with laying hens. Therefore, the purpose of this study was to determine and compare the digestibility of amino acids for laying hens fed three different diets during an acute exposure to heat stress conditions.

MATERIALS AND METHODS

A total of 30 commercial White Leghorn hens (61 wk of age) were moved from a commercial type cage layer facility and singly housed in an environmentally controlled facility. They were each fed an 18% CP standard layer ration (Table 1, Diet 1) and provided water for ad libitum intake. A 17-h daily photoperiod was maintained throughout the experiment. The hens were exposed to a constant thermoneutral temperature of 21 C for a 12-d adjustment period. At the end of this adjustment period, the hens were randomly fed one of three diets (10 hens per diet) and exposed to three concurrent temperature periods (8 d each) which consisted of : 1) a constant 21 C temperature; 2) a daily cycling temperature of 35 C for 12 h and 29 C for 12 h; and 3) a constant 21 C temperature. The diets were fed for the 24-d experimental period and consisted of : 1) an 18% CP corn-soybean meal diet, 2) Diet 1 with 15% meat and bone meal, and 3) Diet 1 with 5% alfalfa meal and 20% wheat bran (Table 1). These three diets were chosen to determine if the effect of heat stress might be influenced by diet composition; thus, the diets varied in amount of plant versus animal protein and fiber content. It was anticipated that the hens would consume about 90 g of feed per bird per day during the heat stress period and thus, the hens were fed 90 g per day during the first thermoneutral period and ad libitum for the next two periods. Excreta were collected from each bird for 4 h per day during the last 4 d of each experimental period and freeze dried. Chromic oxide (.30%) was used as a digesta marker. Diet and excreta samples were analyzed for amino acids using an amino acid analyzer following hydrolysis in 6N HCl at 110 C for 24 hr (Spackman et al., 1958). Methionine and cystine were determined using the performic acid oxidation method described by Moore (1963) except that the samples were diluted with water and lyophilized to remove the excess performic acid. Apparent digestibility of 14 amino acids was then calculated.

All data were analyzed by the General Linear Models procedure (SAS Institute, 1987) for a 3 x 3 factorial arrangement of treatments (Steel and Torrie, 1980) with temperature period and diet type as main effects. Differences between individual treatment means were assessed using the least significant difference test (Steel and Torrie, 1980).

RESULTS

There were no significant interaction effects of diet and temperature period on any amino acid digestibilities calculated. For all amino acid digestibilities calculated except Tyr, there was a significant diet effect (P < 0.05) (Table 2). Digestibility of Asp and Glu was higher in the corn-soybean meal diet than in the other two diets. Digestibility of Ala, Leu, Phe, Thr, and Val in the 15% meat and bone meal diet was higher (P < 0.05) than in the other two diets. Digestibility of Arg, His, Ile, Lys, and Ser were not different between the corn-soybean meal and 15% meat and bone meal diets, but both were higher (P < 0.05) than in the diet containing alfalfa meal and wheat bran. Digestibility of all but three of the amino acids was higher in the 15% meat and bone meal diet than in the diet containing alfalfa meal and wheat bran.

Heat stress or temperature period generally had no significant effect on amino acid digestibility except for Lys and His (Table 3). Lysine digestibility was higher (P < 0.05) during the heat stress period compared to the initial thermoneutral period. During the thermoneutral recovery period, Lys digestibility decreased slightly to a level which was not different than during the initial thermoneutral period. Histidine digestibility was higher during the heat stress period compared to both the initial and recovery thermoneutral periods. Lysine and His digestibility were the only two amino acids which were both significantly affected by both the type of diet fed and temperature exposure.

DISCUSSION

The results of this study showed that acute heat stress exposure did not have any adverse effect on amino acid digestibility in laying hens. Earlier work by Zuprizal et al. (1993) and Wallis and Balnave (1984) showed that amino acid digestibility was significantly affected when broilers were subjected to increasing ambient temperatures. In the Wallis and Balnave (1984) study, male and female broilers (30 d and 50 d) were exposed to a 21 or 31 C temperature period and ileal amino acid digestibility was determined. They showed that increasing the temperature from 21 to 31 C caused a significant depression in Thr, Ala, Met, Ile, and Leu digestibility. Zuprizal et al. (1993) also showed digestibility of most amino acids were significantly depressed for broilers subjected to a 32 versus a 21 C temperature period and fed either a whole rapeseed meal, a dehulled rapeseed meal, or a soybean meal diet. In addition, the effect of heat stress was more pronounced in females versus males. The reason for the lack of effect of heat stress in our study compared to the Wallis and Balnave (1984) and Zuprizal et al. (1993) studies is unknown. However, the differences in results may be associated with type of bird used and/or experimental methodology. The earlier studies used broiler chickens whereas our study used laying hens. In the Zuprizal et al. (1993) study, broilers were exposed to a 32 C constant temperature period from four to six wk of age and, then the birds were force-fed a single small quantity of the experimental diets. Perhaps the constant high temperature produces a greater negative effect on amino acid digestibility than a cycling temperature (29 to 35 C) such as that used in the current study. This cycling temperature was chosen to simulate typical day/night conditions. Direct observations of the hens in this study revealed that gular flutter and rapid panting occurred during the heat stress period.

The primary effect of diet type was that the amino acid digestibility of a high-fiber diet containing wheat bran and alfalfa meal was lower than the corn-soybean meal diet and the 15% meat and bone meal diet. The negative effect of the high-fiber diet on amino acid digestibility was not unexpected. Several studies have shown that excretion of N and amino acids are increased as dietary fiber is increased (Beames and Eggum, 1981; Parsons et al., 1983). These results indicate that feeding high-fiber diets may reduce availability of amino acids for laying hens.

REFERENCES

Beames, R.M., and B.O. Eggum, 1981. The effect of type and level of protein, fibre and starch on nitrogen excretion patterns in rats. Brit. J. Nutr. 46:301-313.

Howlider, M.A.R., and S.P. Rose, 1987. Temperature and the growth of broilers. World's Poultry Sci. J. 43:228-237.

Hurwitz, S., M. Weiselberg, U. Eisner, I. Bartov, G. Riesenfeld, M. Sharvit, A. Niv, and S. Bornstein, 1980. The energy requirements and performance of growing chickens and turkeys as affected by environmental temperature. Poultry Sci. 59:2290-2299.

Marsden, A., T.R. Morris, and A.S. Cromarty, 1987. Effects of constant environmental temperatures on the performance of laying pullets. Br. Poult. Sci. 28:361-380.

Moore, S., 1963. On the determination of cysteine as cysteic acid. J. Biol. Chem. 238:235-237.

Parsons, C.M., L.M. Potter, and R.D. Brown, Jr., 1983. Effects of dietary carbohydrate and of intestinal microflora on excretion of endogenous amino acids by poultry. Poultry Sci. 62:483-489.

Peguri, A., and C. Coon, 1991. Effect of temperature and dietary energy on layer performance. Poultry Sci.70:126-138.

SAS Institute, 1987. SAS Users Guide: Statistics. Version 6.04. SAS Institute Inc., Cary, NC.

Savory, J.C., 1986. Influence of ambient temperature on feeding activity parameters and digestive function in domestic fowls. Physiol. Behav. 38:353-357.

Spackman, D.H., W.H. Stein, and S. Moore, 1958. Automatic recording apparatus for use in chromatography of amino acids. Anal. Chem. 30:1190-1206.

Steel, R.G.D., and J.H. Torrie, 1980. Principles and Procedures of Statistics: A Biometrical Approach. 2nd ed. McGraw-Hill Book Co., New York, NY.

Wallis, I.R., and D. Balnave, 1984. The influence of environmental temperature, age and sex on the digestibility of amino acids in growing broiler chickens. Br. Poult. Sci. 25:401-407.

Zuprizal, M. Larbier, A.M. Chagneau, and P.A. Geraert, 1993. Influence of ambient temperature on true digestibility of protein and amino acids of rapeseed and soybean meals in broilers. Poultry Sci. 72:289-295.

TABLE 1. Composition of experimental diets

  Diet
Ingredients and Analysis Corn-SBM Corn-SBM +MBM Corn-SBM +ALF+WB
  -- (%)--
Corn (8.0% CP) 59.41 66.27 39.97
Dehulled soybean meal (SBM) (45% CP) 29.43 12.22 24.12
Meat and bone meal (MBM) (48% CP) -- 15.00 --
Alfalfa meal (ALF) (17% CP) -- -- 5.00
Wheat bran (WB) (15.5% CP) -- -- 20.00
Limestone 8.48 5.56 8.31
Dicalcium phosphate 1.73 -- 1.65
Iodized salt .30 .30 .30
Vitamin mix1 .20 .20 .20
Trace mineral mix2 .15 .15 .15
Chromic oxide .30 .30 .30
Analysis:      
CP 18.00 18.00 18.00
Calcium 3.80 3.80 3.80
Available phosphorus .45 .45 .45
1Supplied per kilogram of diet: vitamin A, 4400 IU; cholecalciferol, 1000 ICU; vitamin E, 11 IU; vitamin B12, .011 mg; riboflavin, 4.4 mg; d-pantothenic acid, 10 mg; niacin, 22 mg; menadione sodium bisulfate complex, 2.33 mg.

2Supplied per kilogram of diet: manganese, 75 mg; iron, 75 mg; zinc, 75 mg; copper, 5 mg; iodine, .75 mg.

TABLE 2. Main effect of dietary treatment on apparent digestibility of amino acids1

  Dietary treatment  
Amino acid Corn-SBM2 Corn-SBM + MBM2 Corn-SBM +

ALF + WB2

Pooled SEM
  -- (%) --  
Alanine 84.2b 85.8a 81.0c .5
Arginine 90.2a 89.6a 88.1b .3
Aspartic acid 86.1a 84.9b 84.2b .5
Glutamic acid 90.4a 89.6b 89.3b .2
Histidine 87.1a 87.3a 85.7b .3
Isoleucine 85.3a 86.1a 83.9b .5
Leucine 88.7b 89.8a 86.4c .3
Lysine 83.8a 84.6a 81.6b .4
Phenylalanine 88.2b 89.4a 87.0c .3
Proline 89.0ab 90.7a 88.4b .8
Serine 86.6a 87.3a 84.6b .5
Threonine 82.2b 84.1a 80.3c .4
Tyrosine 89.9a 88.3a 88.6a .7
Valine 84.9b 86.3a 82.1c .4
Mean 86.9 87.4 85.1  
a,b,cMeans within a row with no common superscript differ significantly (P < 0.05).
1Amino acid digestibility values were determined from pooled excreta collections (4 h per day) for 10 hens per diet during the last 4 d of each 8-d temperature period. Values represent the main effect of diet and are averaged over the three temperature periods.

2SBM = soybean meal, MBM = meat and bone meal, ALF = alfalfa meal, WB = wheat bran.

TABLE 3. Main effect of temperature period on apparent digestibility of amino acids1

  Temperature period2  
Amino acid TN HS TN recovery Pooled SEM
  -- (%) -- .5
Alanine 83.4a 84.2a 83.4a .3
Arginine 89.2a 89.8a 88.9a .5
Aspartic acid 84.9a 85.4a 84.9a .2
Glutamic acid 89.5a 90.1a 89.6a .3
Histidine 86.0b 87.7a 86.4b .5
Isoleucine 85.1a 84.9a 85.2a .3
Leucine 88.0a 88.7a 88.3a .4
Lysine 82.5a 84.0a 83.5ab .3
Phenylalanine 87.9a 88.3a 88.3a .8
Proline 89.6a 89.0a 89.5a .5
Serine 86.2a 86.2a 86.1a .4
Threonine 82.0a 82.4a 82.0a .7
Tyrosine 89.2a 89.6a 88.0a .4
Valine 84.3a 84.8a 84.2a  
Mean 86.3 86.8 86.3  
a,bMeans within a row with no common superscript differ significantly (P < .05).
1Amino acid digestibility values were determined from pooled excreta collections (4 h per day) for 10 hens per diet during the last 4 d of each 8-d temperature period. Values represent the main effect of diet and are averaged over the three diets fed.
2Temperature periods are concurrent 8-d periods of: 1) TN (constant 21 C); 2) HS (daily cycling temperature of 35 C for 12 h and 29 C for 12 h); 3) TN recovery (constant 21 C).

1. Supported by Illinois Agricultural Experiment Station Hatch Project ILLU-35-0327.

2. To whom correspondence should be addressed: 282 Animal Sciences Laboratory, 1207 W. Gregory Drive, Urbana, IL 61801, Telephone: (217)244-0195, Fax: (217)333-7861, E-mail: kkoelkeb@uiuc.edu







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