Poult. Sci.
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Poult Sci 2008. 87:1276-1280. doi:10.3382/ps.2007-00299
© 2008 Poultry Science Association
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ENVIRONMENT, WELL-BEING, AND BEHAVIOR

Effect of Potassium Chloride Supplementation in Drinking Water on Broiler Performance Under Heat Stress Conditions

T. Ahmad*, T. Khalid{dagger}, T. Mushtaq{ddagger},1,2, M. A. Mirza{ddagger}, A. Nadeem§, M. E. Babar§ and G. Ahmad#

* Faculty of Veterinary and Animal Sciences, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan 46300; {dagger} Department of Zoology, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan 46300; {ddagger} Institute of Animal Nutrition and Feed Technology, University of Agriculture, Faisalabad, Pakistan 38040; § Faculty of Animal Production and Technology, University of Veterinary and Animal Sciences, Lahore, Pakistan 54000; and # Al-Watnia Poultry, Buraidah, Kingdom of Saudi Arabia 51431

2 Corresponding author: tmmirza{at}fsd.paknet.com.pk or tmmirza{at}ghazibrothers.com


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
The effect of water supplementation of KCl on performance of heat-stressed Hubbard broilers was evaluated in the present experiment. The 3 experimental treatments (i.e., control, 0.3 and 0.6% KCl) were allocated to 3 replicates of 15 birds each. The control group was kept on dugout tap water, whereas the other 2 groups were supplied water supplemented with 0.3 and 0.6% KCl (wt/vol) by supplementing 3 and 6 g of KCl, respectively, per liter of drinking water. Broilers were provided ad libitum access to feed and water for the experimental period of 7 to 42 d of age and kept in open-sided house. The birds were reared under continuous thermostress (minimum 28.2 ± 1.02 and maximum 37.5 ± 0.78°C) environment. Supplementing drinking water with 0.6% KCl reduced panting-phase blood pH to 7.31 and significantly increased live BW gain by 14.5 (P = 0.036) and 7.9% (P = 0.029) at 28 and 42 d of age, respectively, relative to control. An improved (P = 0.04) feed:gain and lowered body temperature were noted in groups supplemented with 0.6% KCl as compared with control and 0.3% KCl. Enhanced physiological adaptation with 0.6% KCl was evidenced by a more favorable pH during the panting phase in the present study. These findings demonstrated a possibility of better broiler live performance through KCl supplementation under conditions of severe heat stress (35 to 38°C).

Key Words: potassium chloride • drinking water • heat stress • broiler


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
High environmental temperature is one of the most serious factors affecting production performance of broilers by reducing their feed intake, lowering BW, increasing mortality, and disturbing acid-base balance (Mushtaq et al., 2005; Ahmad and Sarwar, 2006). There are certain behavioral and physiological mechanisms by which the birds try to dissipate their body heat. Birds can increase their effective surface area by lifting their wings or lose heat through conduction by spreading out on the ground. An increase in ambient temperature beyond the thermoneutral zone of the bird causes the birds to start panting, as a physiological mechanism for controlling body temperature. Hyperventilation results in dehydration and loss of carbon dioxide from blood and tissues. In turn, the lower concentration of hydrogen ions causes a rise in plasma pH and, ultimately, respiratory alkalosis (Borges et al., 2007), which is also related to negative mineral balance for K+ and Na+. During respiratory alkalosis, naturally birds attempt to correct blood pH by excreting negatively charged bicarbonate ions. The bicarbonate ions must be coupled with positively charged ions, such as sodium (Na+) or potassium (K+), before being excreted through urine. Ultimately, the losses of Na+ or K+, or both, in urine result in acid-base imbalance.

Potassium, the most abundant intracellular cation, is involved in many metabolic processes, including nerve conduction, excitation-contraction in muscles, and regulation of cell volume. Consequently, changes in K+ homeostasis profoundly affect cellular functions (Their, 1986). The thermotolerance of chickens exposed to acute heat stress could be improved by supplementing either diet with K salts (Ahmad et al., 2005) or drinking water with KCl (Smith and Teeter, 1987a). Similarly, a daily potassium intake of 1.8 to 2.3 g has been recommended for maximum BW gain in broilers under hot conditions (Rao et al., 2002). However, providing K+ as potassium bicarbonate exaggerated respiratory alkalosis (Borges et al., 2003a), and it failed to influence either body temperature or plasma electrolytes at high temperature (Smith and Teeter, 1987b,c). Based on these findings, it has been postulated that drinking an electrolyte solution rich in K+ might elicit favorable changes in the physiological adjustments to heat-stressed broilers. The present study, therefore, was conducted to determine the effects of 2 levels KCl supplementation (i.e., 0.3 and 0.6%) through drinking water on the performance of broiler chickens under heat stress conditions.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 REFERENCES
 
The experimental procedure was approved by the Advance Study and Research Board, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan.

Housing and Management

One hundred fifty one-day-old male Hubbard broiler chicks were used in the present study. The birds were kept to 42 d of age in an open-sided house fitted with wire mesh and side wall cloth curtains. Chicks were brooded together to 7 d at a constant room temperature of 35°C. At 7 d, 135 chicks were randomly assigned to the 9 experimental units each having 15 chicks in such a way that each unit had an equal mean BW. The birds were kept in floor pens having saw dust as bedding material over a concrete floor. The temperature was maintained at 32°C for the second week, and thereafter, cyclic day and night temperature was followed (Table 1Go). Light was made available to the birds around the clock. This experiment was conducted during May and June, considered as severe hot months in Pakistan.


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  		Table 1. Average weekly room temperature and RH
 
Diets and Experimental Treatments

Basal starter (1 to 28 d) and finisher (29 to 42 d) diets were formulated (Table 2Go) according to the nutrient requirement recommendations of NRC (1994) for broiler chickens except for crude protein and metabolizable energy, which were slightly lower than the recommendations for starter diets (Table 3Go). Water was supplemented with 0.3 and 0.6% KCl (wt/vol) by supplementing 3 and 6 g of KCl, respectively, per liter of drinking water. Control birds received dugout tap water throughout the experiment. Feed and water were supplied ad libitum to each group. Feed samples were analyzed for nutrient composition by AOAC (1990). Feed Na+ and K+ contents were determined by flame photometer (AOAC, 1990) and Cl– by titration with silver nitrate (Lacroix et al., 1970). Weekly drinking water samples were also analyzed for Na+, K+, and Cl– contents, and only traces of these ions (Na+ = 0.30; K+ = 0.12; Cl– = 0.39 mg/L) were noted.


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  		Table 2. Ingredient composition of basal starter (1 to 28 d) and finisher (29 to 42 d) diets
 

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  		Table 3. Nutrient composition of basal starter (1 to 28 d) and finisher (29 to 42 d) diets
 
Data Recording

Data on feed intake and BW gain were recorded on a weekly basis, whereas mortality was recorded daily throughout the experimental period. Feed intake was corrected for mortality. The rectal temperature was monitored 3 times a week after 14 d of age. For this purpose, 2 birds per pen were randomly selected and marked to record rectal temperature in the morning and afternoon, corresponding to the coolest and warmest times of day, respectively. Rectal temperature was monitored by inserting the digital thermometer probe 3 cm deep into the rectum of the bird. The blood pH and carcass characteristics were determined at 42 d of age. Venous blood samples (4 mL) were collected during panting on the 42 d by puncture of the brachial vein, in 2 birds per pen by using sterilized syringes containing anticoagulant (Li-heparin, 50 IU/mL). The syringes were capped, kept in ice, and whole blood pH analyses were performed within 30 min after the blood collection by using a pH meter (Beckman’s pH meter 243, Beckman Coulter, Fullerton, CA) already standardized with known buffer solutions. After the termination of the growth study on d 42, feeders and waters were withdrawn for 6 and 3 h, respectively. Two birds from each pen were randomly selected, weighed, and slaughtered by jugular vein slit for carcass measurements. Bird live weight and dressed weight with and without viscera were determined (Ahmad et al., 2005; Mushtaq et al., 2005).

Statistical Analyses

The pen mean was an experimental unit for feed intake, BW gain, feed:gain, and mortality. For the analyses of rectal temperature, carcass parameters, and blood pH, observations on individual chicks were used with pen as an experimental unit. The percentage of data on mortality was transformed to Formula for statistical analyses (Mead et al., 1993). The transformed data followed the normal distribution. The data presented herein were backtransformed for comparison. The experiment was conducted as a completely randomized design. The effect of water supplementation with KCl was determined by the ANOVA technique using Minitab 13.1 (Minitab Inc., State College, PA). The level of significance was 0.05 unless otherwise stated. In case of significance (P ≤ 0.05), means were separated by Duncan’s multiple range test (Steel and Torrie, 1981).


   RESULTS AND DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
REFERENCES
 
The temperature and humidity data during the experiment are presented in Table 1Go. The BW gain remained unaffected at 14 d of age (Table 4Go). However, water treatment with 0.6% KCl resulted in significantly higher BW gain at 28 and 42 d than in other treatments. The increase in BW gain was more pronounced with supplementation of 0.6% KCl compared with 0.3% KCl or control group at 42 d of age. However, no significant difference was found between control and 0.3% KCl treatments at 28 and 42 d of age. The group offered 0.6% KCl consistently increased the BW gain by 14.5 and 7.9% at 28 and 42 d of age, respectively, compared with the control. The results of the present study were in agreement with Ait-Boulahsen et al. (1995), who indicated a net increase in BW gain with 0.6% KCl as compared with 0.3 and 0.9% KCl. A linear increase in BW gain with 0.05, 0.1, and 0.15% K supplementation in drinking water as KCl was also noted by Teeter and Smith (1986). Similarly, KCl supplementation has also been reported to increase the BW gain and survivability in chickens to varying degrees (Teeter and Smith, 1986; Smith and Teeter, 1987b,c). An increase in ambient temperature leads to lowering of plasma K+, and an increase in BW gain may be due to the increase in plasma K+ concentration by KCl supplementation. In support of this hypothesis, Ahmad et al. (2005) reported that Na+, K+, and Cl– supplements resulted in higher blood Na+, K+, and Cl– levels, respectively. They were of the view that changes in blood Na+, K+, and Cl– levels might contribute to the normalization of blood electrolyte balance that led to the improvement in BW gain and overall live performance of broilers kept at high temperature (Takahashi and Akiba, 2002).


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  		Table 4. Effect of KCl supplementation via drinking water on feed intake (FI), BW gain, and feed:gain of broiler chicks reared under heat-stressed conditions
 
A significant improvement in feed:gain was noted with 0.6% KCl supplementation at 28 (P = 0.003) and 42 d (P = 0.001) of age. However, no significant (P > 0.18) effect of KCl supplementation was observed on FI at 14, 28, and 42 d of age in the present experiment. The present findings are not consistent with Ait-Boulahsen et al. (1995), who reported increased feed intake with added KCl at 0.6%. The significantly improved feed:gain with 0.6% KCl supplementation might be due to higher BW gain of that group, because feed intake was not affected by KCl supplementation. A positive correlation between BW gain and improved feed:gain was also noted by Mushtaq et al. (2005), who supplemented broiler diets with different electrolytes at a constant dietary electrolyte balance of 250 mEq/kg during the summer season. As discussed above, the normalization of blood electrolyte balance led to improved BW gain and subsequently to the better feed:gain.

Water supplemented with 0.6% KCl significantly reduced the blood pH to 7.31 at 42 d in the present study (Table 5Go). On the other hand, 0.3% KCl and control treatments did not reduce the alkalotic blood pH to a level considered as favorable (pH 7.28; Hurwitz et al., 1973) for physiological functions of a bird. The results of the present study suggested that 0.3% KCl was insufficient to reduce the alkalotic blood pH as compared with 0.6% KCl. In general, hyperthermia induced hyperventilation and associated respiratory alkalosis, which led to increased blood pH and decreased bicarbonate concentration and partial pressure of CO2 (Borges et al., 2003a). Presumably, KCl addition might not affect blood pH considerably, because it contains both positive (K+) and negative (Cl–) ions. However, the reduction in blood pH in the present study was in agreement with the findings of Ait-Boulahsen et al. (1995), who reported decreases in blood pH during heat stress with 0.6% KCl supplementation. Likewise, Teeter and Smith (1986) noted a linear increase in BW gain and no effect on blood pH when 0.05, 0.10, and 0.15% K+ as KCl was supplemented in drinking water. One possible reason for low pH with 0.6% KCl in the present study might be the acidogenic effect of Cl– and maintenance of blood electrolyte balance due to increased blood K+ contents (Ahmad et al., 2005). The enhanced adaptive response in birds exposed to heat stress for a long time (Borges et al., 2003b) might be another reason for low blood pH with KCl supplementation.


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  		Table 5. Effect of KCl supplementation via drinking water on 42-d blood pH and mean rectal temperature and mortality and carcass weight of broiler chicks up to 42 d reared under heat-stressed conditions
 
Average rectal temperature from 15 to 42 d was significantly affected by 0.6% KCl supplementation (Table 5Go) and was lower that those of 0.3% KCl supplementation and control in the present study. The 0.3% KCl treatment was not different from the control group for deep body temperature. These findings are consistent with that of Ait-Boulahsen et al. (1995), who reported an improvement in heat tolerance of chickens that drank water supplemented with 0.6% KCl. It is well known that supplementation of diet or drinking water with electrolytes improved the water consumption in birds reared under heat stress conditions (Borges et al., 2003a,b, 2007; Ahmad et al., 2005; Mushtaq et al., 2007). Borges et al. (2000) reported an increased water intake in broilers supplemented with 1.0% KCl from 21 d onwards. The increase in water consumption acts as a heat sink from the body and helps the birds in maintaining deep body temperature (Smith and Teeter, 1988; Belay and Teeter, 1993). Increased live performance by 0.6% KCl supplementation may also be attributed to lowered body temperature by more water consumption that resulted in more energy diversion toward BW gain, rather than dissipating body heat load. However, further investigations are suggested in this regard.

Nonsignificant effects of KCl supplementation were noticed on mortality, carcass weight, leg, breast, and abdominal fat weights (data not shown). The results are in accordance with those of Smith and Teeter (1987b), who showed that 3 types of salt solutions increased water consumption of cyclically heat-stressed broilers but did not affect carcass dressing or feed efficiency. Similarly, Souza et al. (2002) did not report any effect of KCl supplementation on carcass response or abdominal fat.

In conclusion, KCl supplementation via drinking water showed significant effects on overall performance of heat-stressed broilers especially at later stages of life. However, supplementation of drinking water with 0.3% KCl was not sufficient to alleviate the adverse effects of heat stress and a minimum of 0.6% KCl was required to get the optimum performance between ambient temperatures of 35 to 38°C.


   FOOTNOTES
 
1 Present location: Ghazi Brothers, Karachi, Pakistan 75350. Back

Received for publication July 20, 2007. Accepted for publication March 28, 2008.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
Ahmad, T., and M. Sarwar. 2006. Dietary electrolyte balance: Implications in heat stressed broilers—A review. World’s Poult. Sci. J. 62:638–653.[Web of Science]

Ahmad, T., M. Sarwar, M. Mahr-un-Nisa, A. Ahsan-ul-Haq, and Z. Zia-ul-Hasan. 2005. Influence of varying sources of dietary electrolytes on the performance of broilers reared in a high temperature environment. Anim. Feed Sci. Technol. 120:277–298.[CrossRef]

Ait-Boulahsen, A., J. D. Garlich, and F. W. Edens. 1995. Potassium chloride improves the thermotolerance of chickens exposed to acute heat stress. Poult. Sci. 74:75–87.[Web of Science][Medline]

AOAC. 1990. Official Methods of Analysis. 15th ed. Association of Official Analytical Chemists, Washington, DC.

Belay, T., and R. G. Teeter. 1993. Broiler water balance and thermobalance during thermoneutral and high ambient temperature exposure. Poult. Sci. 72:116–124.[Web of Science]

Borges, S. A., J. Ariki, V. M. B. de Moraes, A. A. Pedroso, D. Salvador, and C. L. Martins. 2000. Potassium chloride supplementation in broilers diets during summer. Ars Vet. 16:64–70.

Borges, S. A., A. V. Fischer da Silva, J. Ariki, D. M. Hooge, and K. R. Cummings. 2003a. Dietary electrolyte balance for broiler chickens under moderately high ambient temperatures and relative humidities. Poult. Sci. 82:301–308.[Abstract/Free Full Text]

Borges, S. A., A. V. Fischer da Silva, J. Ariki, D. M. Hooge, and K. R. Cummings. 2003b. Dietary electrolyte balance for broiler chickens exposed to thermoneutral or heat-stress environments. Poult. Sci. 82:428–435.[Abstract/Free Full Text]

Borges, S. A., A. V. Fischer da Silva, and A. Maiorka. 2007. Acid-base balance in broilers. Worlds Poult. Sci. J. 63:73–81.[Web of Science]

Hurwitz, S., I. Cohen, and A. Bar. 1973. Sodium and chloride requirements of chick: Relationship to acid-base balance. Poult. Sci. 52:903–909.[Web of Science][Medline]

Lacroix, R. L., D. R. Keeney, and L. M. Welsh. 1970. Potentiometric titration of chloride in plant tissue extracts using the chloride ion electrode. Commun. Soil Sci. Plant Anal. 1:1–6.

Mead, R., R. N. Curnow, and A. M. Hasted. 1993. Statistical Methods in Agriculture and Experimental Biology. 2nd ed. Chapman and Hall, London, UK.

Mushtaq, T., M. A. Mirza, M. Athar, D. M. Hooge, T. Ahmad, G. Ahmad, M. M. H. Mushtaq, and U. Noreen. 2007. Effect and interactions of dietary sodium and chloride on broiler starter performance (twenty-eight to forty-two days of age) under subtropical summer conditions. J. Appl. Poult. Res. 16:161–170.[Abstract/Free Full Text]

Mushtaq, T., M. Sarwar, H. Nawaz, M. A. Mirza, and T. Ahmad. 2005. Effect and interactions of sodium and chloride on broiler starter performance (one to twenty-eight days) under subtropical summer condition. Poult. Sci. 84:1716–1722.[Abstract/Free Full Text]

NRC. 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC.

Rao, S. V. R., D. Nagalakshmi, and V. R. Reddy. 2002. Feeding to minimize heat stress. Poult. Int. 41:15.

Smith, M. O., and R. G. Teeter. 1987a. Effects of potassium chloride and fasting on body weight gain and survival of heat stressed broilers. Poult. Sci. 66(Suppl. 1):179. (Abstr.)

Smith, M. O., and R. G. Teeter. 1987b. Evaluation of sodium and potassium salts for heat stressed broilers. Poult. Sci. 66(Suppl. 1):179. (Abstr.)

Smith, M. O., and R. G. Teeter. 1987c. Potassium balance of the 5 to 8 week-old broiler exposed to constant heat or cycling high temperature stress and the effects of supplemental potassium chloride on body weight gain and feed conversion. Poult. Sci. 66:487–492.[Medline]

Smith, M. O., and R. G. Teeter. 1988. Practical application of potassium chloride and fasting during naturally occurring summer heat stress. Poult. Sci. 67(Suppl. 1):36. (Abstr.)

Souza, B. B., A. G. Bertechini, A. S. Teixeira, J. A. F. Lima, S. L. Pereira, and E. J. Fassani. 2002. The effects of potassium and ammonium chlorides on the performance and deposition of abdominal fat in carcass of broilers raised in summer. Rev. Bras. Cienc. Avíc. 4:209–218.

Steel, R. G. D., and J. H. Torrie. 1981. Principles and Procedures of Statistics. McGraw Hill Book Co. Inc., New York, NY.

Takahashi, K., and Y. Akiba. 2002. Effect of oral administration of Diakur (a glucose and electrolyte additive) on growth and some physiological responses in broilers reared in a high temperature environment. Asian-australas. J. Anim. Sci. 15:1341–1347.

Teeter, R. G., and M. O. Smith. 1986. High chronic ambient temperature stress effects on broiler acid-base balance and their responses to supplemental ammonium chloride, potassium chloride and potassium carbonate. Poult. Sci. 65:1777–1781.[Web of Science][Medline]

Their, S. O. 1986. Potassium physiology. Am. J. Med. 80(Suppl. 4A):3–7.[Web of Science][Medline]





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