Responses of broiler chickens to incremental levels of water deprivation: Growth performance, carcass characteristics, and relative organ weights

Amirah Mhmoud; Mbusiseni Vusumuzi Mkwanazi; Sithembile Zenith Ndlela; Mehluli Moyo; Michael Chimonyo

doi:10.1515/opag-2022-0184

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Responses of broiler chickens to incremental levels of water deprivation: Growth performance, carcass characteristics, and relative organ weights

Amirah Mhmoud , Mbusiseni Vusumuzi Mkwanazi , Sithembile Zenith Ndlela , Mehluli Moyo and Michael Chimonyo

Published/Copyright: September 6, 2023

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From the journal Open Agriculture Volume 8 Issue 1

Abstract

The objective of the study was to assess the effect of varying levels of water deprivation on growth performance, carcass characteristics, and internal organ weight of broiler chickens. Ninety unsexed Ross 308 chicks 2 weeks old were randomly assigned to five water deprivation periods of 0, 6, 12, 18, and 24 h. Each treatment was replicated three times with six birds per replicate. Broiler chickens were given water ad libitum (0 h) or for 30 min at 6-, 12-, 18-, and 24-h intervals. Average daily feed intake (ADFI), average daily gain (ADG), and feed conversion ratio (FCR) were determined on a weekly basis. A negative linear relationship (P < 0.05) existed between water deprivation and ADFI. The increase in water deprivation level resulted in ADFI decreasing at an increasing rate. The R ² value was 0.94. There was no relationship between water deprivation on ADG and FCR (P > 0.05). There was a quadratic relationship between water deprivation and cold dress mass (CDM) and warm dress mass. As the level of water deprivation increased, there were linear increases in relative weight of gizzard, spleen, heart, lungs, liver, and gastrointestinal tract (P < 0.001). The organ weights of the broiler chickens revealed the ability of birds to withstand of up to 24 h. Using differential of quadratic equations, the maximum time of water deprivation that did not negatively affect CDM was estimated to be 4 h.

Keywords: birds; heart; liver; spleen; water security

1 Introduction

Water scarcity because of prolonged droughts has become a topical issue, particularly in developing countries of Sub-Saharan Africa. Water scarcity and unavailability is expected to increase in the future due to changes in climate and increasing human population. Such factors are raising the demand for available water resources. In most parts of Southern Africa, the available water cannot sustain the human population and livestock sector as some of the water bodies are getting depleted. Chicken meat contains a favourable ratio of polyunsaturated fatty acids:saturated fatty acids (PUFA:SFA), making it beneficial to consumers [1]. Broiler meat is inexpensive compared to other animal protein sources on the market [2]. In comparison with other meat choices, chicken meat does not have any religious restrictions, making it an ideal product for a wide range of consumers. Broiler chickens cannot survive long periods of water deprivation because water is crucial in nutrient metabolism [2]. A decrease of 10% in body water through dehydration and excretion may result in serious physiological disorders.

Water intake greatly facilitates the genetic potential for growth in broiler chickens [2]. Water deprivation has a high potential to reduce feed consumption, thus leading to poor growth [3]. Water shortages lower the extent of digestion [2]. In principle, ad libitum water supply is recommended for broiler chickens. There are, however, several scenarios when broiler chickens are deprived of water. For example, broiler chickens have little or no access to water during catching, transportation from farm to abattoir, and during lairage. Water deprivation during transportation may influence the physico-chemical, sensory, and carcass characteristics of broiler meat [4]. In Southern Africa, 80% of households that live in resource-limited communal production systems keep indigenous chicken strains [5]. The conditions are fragile and marginal, where there is a lack of safe drinkable water for both human and livestock production.

In these systems, chickens usually subsist on unpalatable tainted wastewater from bathrooms and kitchens [5]. The extent to which broiler chickens can survive water restrictions and deprivation that most farmers face is, however, unknown. Although a substantial amount of work has been reported on the effects of water restriction in broiler chickens, the optimal time of water deprivation that has little adverse effects on broiler performance, carcass quality, and relative organ weights of broiler chickens needs to be ascertained. Water, being a scarce resource, should be managed sustainably. The limited water supply due to climate change means that supplying water to both humans and livestock at an acceptable level of quality and accessibility may be costly. Investments will be required for operations and maintenance costs of infrastructure related to the treatment and distribution of water.

Water-scarce areas, which are mostly inhabited by resource-limited farmers, also have higher water costs due to extensive water distribution systems [4]. Such information would help assist with water conservation strategies and efficient use of available water. The study will also benefit smallholder farmers by providing valuable information on the thresholds at which broiler chickens can tolerate or withstand water deprivation. The objective of the study was to determine the response of broiler chickens to varying levels of water restriction on growth performance, carcass characteristics, and organ weights of broiler chickens. It was hypothesised that there was no relationship between water deprivation and growth performance, carcass characteristics, and organ weights of broiler chickens.

2 Materials and methods

2.1 Study site

The study was conducted at Ukulinga Research Farm, University of KwaZulu-Natal, Pietermaritzburg, South Africa. The farm is located at 29°24′E and 30°24′S at an altitude of 775 m above the sea level. The daytime mean temperatures in the hot wet season reach highs of around 29°C with variations ranging from 28.2 to 43°C. The average rainfall is 735 mm, which occurs mostly in the hot wet season, with light to moderate frost falling occasionally in winter.

2.2 Birds, treatments, and their management

One hundred day old Ross 308 broiler chicks were fed a commercial starter diet (1–14 days), a grower diet (14–28 days), and a finisher diet (28–35 days) (Table 1). The starter feed was provided as a mash, while the grower and finisher diets were provided in pellet form. During the 14-day brooding period, birds were provided with water and feed ad libitum using nipple drinkers and tube feeders, respectively. At the end of the brooding period, 90 birds were weighed and randomly allocated to water deprivation treatments. Birds were deprived of water for 0 h or ad libitum, 6, 12, 18, and 24 h/day. Each treatment was replicated three times with six birds per replicate. The birds were allowed an acclimatisation period of 4 days prior to data collection. For ethical reasons, birds with restricted access to water were allowed a 30-min ad libitum access to water between deprivation periods. Wood shavings were used as bedding and changed on a weekly basis. At day old, room temperature was set at 30°C and gradually reduced by 1°C until the final temperature at day 35 was 21°C and relative humidity was 35%. Birds were subjected to a 12L:12D lighting program throughout the study.

Table 1

Chemical composition of diet fed to broilers

Ingredient composition (g/kg⁻¹ DM)	Starter	Grower	Finisher
Maize	610.4	660.5	659.0
Soyabean meal	310.3	250.8	254.4
Fish meal	26.4	30.6	41.0
Sunflower oil	22.0	24.0	17.1
Limestone	14.2	14.1	13.4
Monocalcium phosphate	8.4	7.0	7.6
DL-methionine	3.2	7.9	2.3
Salt	3.2	2.9	3.3
Vitamin–mineral premix^*	1.4	1.4	1.4
l-Lysine HCl	0.3	0.7	0.8
l-Threonine	0.2	0.1	0.3
Non-phytate P	3.8	4.8	3.5
Met + cysteine	7.1	6.3	7.0
Threonine	6.4	5.6	8.0
Chemical composition (g/kg ⁻¹ DM)
Crude protein	200	180	160
Metabolisable energy (MJ/g DM)	12.8	13.0	13.6
ME:CP ratio (MJ/g)	0.06	0.07	0.085
Crude fat	25.0	25.0	25.0
Fibre	50.0	60.0	70.0
Moisture	120	120	120
Calcium	12.0	12.0	6.0
Phosphorus	6.00	5.50	5.00
Lysine	12.0	10.0	9.00

*Supplied as per kg of feed: 60 mg iron; 40 mg manganese; 4 mg copper; 70 mg zinc; 0.8 mg iodine; 0.3 mg selenium; 9,000 IU vitamin A; 2,000 IU vitamin D; 15 IU of vitamin E; 2 mg vitamin K; 1 mg of vitamin B12; 0.30 mg biotin; 250 mg choline chloride; 0.75 mg folic acid; 20 mg niacin; 5.3 mg pantothenic acid; 7.5 mg pyridoxine; 7.5 mg riboflavin and 2.1 mg thiamine. ME – metabolisable energy; CP – crude protein.

Ethical approval: The research related to animal use has been complied with all the relevant national regulations and institutional policies for the care and use of animals.

2.3 Measurements

2.3.1 Growth performance

Performance variables were determined every week for 18 days following an adaptation period of 4 days. Body weight (BW) changes were determined by measuring BWs of each bird on a weekly basis. Average daily gain (ADG) (kg/day) was determined by dividing the difference between BW at the beginning and end of each week by 7. Weekly feed intake (WFI) was calculated by the difference between the weights of the feed at the beginning and fed out at the end of the week. Average daily feed intake (ADFI) was determined by dividing WFI by 7. The feed conversion ratio (FCR) was calculated by dividing the ADFI by ADG. Scaled feed intake (SFI) was calculated as grams feed per kilogram BW per day.

2.3.2 Carcass characteristics and organ weights

At the end of the trial, six birds from each treatment were randomly slaughtered to evaluate carcass characteristics and organ weights. Chickens were slaughtered at 08:00 h by electrical stunning to make them unconscious, and the jugular vein was slit with a sharp knife and bled (exsanguination). After bleeding, the birds were scalded in hot water for feather plucking. Carcasses were eviscerated and weighed using a digital electronic scale (Jadever JPS-1050, Micro Precision Calibration Inc., USA). The liver, lungs, heart, spleen, and gizzard were collected and weighed. The length of the gastrointestinal tract from the gizzard to the cloaca was measured using a flexible measuring tape. The weights were expressed relative to the BW of the birds at slaughter. The warm carcass weight was recorded within 30 min of slaughter, and cold carcass weight was determined after chilling in the refrigerator for 24 h at 4°C. The dressing percentage (DP) was calculated as follows;

DP ( % ) = Cold carcass weight live slaughter weight × 100 .

2.3.3 Statistical analyses

The relationships between water deprivation against the ADFI, ADG, FCR, SFI, carcass characteristics, and organ weight were determined using polynomial regression (PROC REG) procedures for SAS 9.4 (2016).

3 Results

3.1 Growth performance

A mortality of <3% was recorded during the entire experimental period across the different treatments. Incorporated as a covariate, the initial BW had no significant effect on growth performance variables. The effect of water deprivation on the ADFI of broiler chickens was significant (P < 0.05); however, there was no effect of water deprivation on the ADG of broiler chickens (P > 0.05). The effect of water deprivation on SFI was significant (Table 2). Relationships between water deprivation levels on ADG, ADFI, SFI, and FCR are given in Table 2.

Table 2

Relationship between water deprivation and ADG, ADFI, scaled feed intake (SFI), and FCR in broiler chickens

Parameter	Water deprivation levels (h)					SEM	Regression coefficient		Significance
	0	6	12	18	24	SEM	Quadratic	Linear
ADG (kg/day)	0.137	0.052	0.074	0.054	0.033	0.031	−0.000038^ns	0.0011^ns	ns
ADFI (kg/day)	0.137	0.133	0.125	0.104	0.093	0.006	−0.000188^ns	−0.0031*	*
SFI (kg feed/kg BWG)	4.334	4.672	4.000	3.576	3.581	0.202	−0.00773^ns	0.133^ns	*
FCR (kg feed/kg gain)	1.929	1.984	1.688	1.758	1.775	0.197	−0.0043^ns	0.08^ns	ns

*P < 0.05; NS: not significant (P > 0.05). Abbreviations: ADG – average daily gain, ADFI – average daily feed intake, SFI – scaled feed intake, FCR – feed conversion ratio.

There was no relationship between water deprivation and ADG (P > 0.05). Water deprivation resulted in a negative linear relationship on ADFI (P < 0.05). As the level of water deprivation increased, ADFI decreased at an increasing rate. The R ² value was 0.94. There was a quadratic relationship between water deprivation and SFI (P < 0.01). The SFI decreased at an increasing rate with an increase in the duration of water deprivation. There was no relationship between water restriction and FCR (Table 2).

3.2 Response in carcass characteristics and organ weights

The responses of carcass characteristics and relative weights of internal organs to varying levels of water deprivation are given in Table 3. There were linear increases in the relative weight of gizzard, spleen, heart, lungs, liver, and gastrointestinal tract (P < 0.001) with an increase in water deprivation levels. The relationship between water deprivation and cold dress mass (CDM) was quadratic. As the duration of water deprivation increased, there was a decrease in CDM (Figure 1) (R ² = 0.84).

Table 3

Carcass and relative organ weight (g) of broiler chickens raised under varying levels of water deprivation time (h)

Carcass and relative organ weight	Water deprivation levels (h)					SEM	Regression coefficient
	0	6	12	18	24	SEM	Quadratic	Linear
WDM (g)	1685.8	1643.5	1671.2	1363.1	1112.5	74.2	−2.058*	−21.17***
CDW (g)	1648.2	1594.2	1640.7	1341.8	1104.8	70.7	−1.413*	−11.60***
DP (%)	74.6	72.3	72.5	70.6	71.1	3.03	ns	ns
Liver (g)	20.4	22.5	20.1	28.2	27.7	1.00	ns	0.089***
Heart (g)	7.21	7.95	7.10	9.94	9.73	0.35	ns	0.032***
Lungs (g)	6.81	7.51	6.71	9.40	9.21	0.33	ns	0.029***
Gizzard (g)	24.5	27.1	24.2	33.8	33.2	1.20	ns	0.108***
Spleen (g)	1.27	1.40	1.25	1.75	1.72	0.06	ns	0.0054***
GIT (cm)	75.8	83.6	74.7	104.6	102.52	3.72	ns	0.333***

DP – dressing percentage, WDM – warm dress mass, CDM – cold dress mass, GIT – gastrointestinal tract, SEM – standard error of mean. Level of significance ***P < 0.001; *P < 0.05.

Figure 1

Relationships between water deprivation levels and carcass weight parameters CDM and WDM.

Water deprivation resulted in a quadratic relationship on warm dress mass (WDM), with an R ² value of 0.96. Increasing the duration of water deprivation resulted in a decrease in WDM; y = −1.4929x ² + 12.045x + 1673.1 (Figure 1), decreasing at an increasing rate. Carcass characteristics (CDM and WDM) decreased due to the increasing duration of water deprivation. The maximum time of water deprivation that did not negatively affect CDM and WDM was 4 and 4.7 h, respectively.

4 Discussion

Water shortage and reduced water quality are anticipated to escalate due to climate change and global warming. It is, therefore, essential to develop sustainable water management strategies for livestock. Broiler chicken production systems have been shown to utilise large quantities of water; hence, there is a need to develop new ways for sustainable water use. For example, it is pivotal to understand the threshold to which farmers can subject broiler chickens to water deprivation. Ad libitum water consumption has been reported to increase water excretion, aggravate wet litter problems, and high ammonia production [6]. No studies have considered the prediction of the responses in growth performance, carcass characteristics, and relative organ weights in broilers exposed to varying lengths of water deprivation.

The observed negative linear relationship between water deprivation level and ADFI conforms to the commonly held notion that water deprivation decreases feed intake. Reduction in feed intake may have been a compensatory strategy to preserve body water by reducing faecal water loss as well as body heat increment [7,2]. Feed intake correlated with water intake; the more water birds consume due to thirst, the increased amount of feed they consume since water acts as a medium for metabolic processes that ensure efficient nutrient utilisation. Any factor that interferes with water intake subsequently affects feed intake [4].

The lack of relationship between water deprivation level and ADG could reflect greater dependence on metabolic water to maintain hydrational homeostasis or a higher capacity of budgeting body water more economically in birds exposed to water stress [5]. Findings by de Jong et al. [8] showed that water deprivation had no long-lasting effects on BWs of broiler chickens. Homeostatic osmoregulation in dehydrated birds is maintained by ingestion of water and reduction of water excretion volume or by using interstitial or intracellular fluids [9]. Birds subjected to water deprivation are expected to utilise metabolites for metabolic energy production to maintain homeostasis. It is possible that the utilisation of interstitial and intracellular fluids, as well as metabolic energy production, is involved in the decrease in ADG [9].

The ADG of birds deprived of water for more than 24 h was, however, difficult to predict. Birds deprived of water have reduced appetite as they use water to help break down and soften the feed. Abdelsamie and Yadiwilo [10] reported a drop in ADG of 18% in birds subjected to a 25% water restriction. The observed lack of relationship between water deprivation and FCR was unexpected. Water deprivation is expected to reduce the efficiency of utilising feed. The decrease in both WDM and CDM as the level of water deprivation increased suggests that water supply should be considered to sustain broiler production enterprises. The CDM, for example, decreased by 33%. As for ADG, the DP was not related to the level of water deprivation, the pattern that is difficult to explain. The quadratic response of WDM and CDM as the level of water deprivation increased suggests that the maximum time of water deprivation that can be employed before negatively affecting CDM and WDM was 4 and 4.7 h, respectively. Water deprivation programs of not more than 4.7 h can be considered to save water in broiler production enterprises.

The observed positive relationship between relative liver weight and water deprivation could be attributed to the liver being able to draw water from the body reserves for its normal metabolic functions. When the liver secretes bile juice with its alkaline medium (sodium), it draws water from the body reserves for its normal metabolism [11]. Therefore, it is possible that during the period of water deprivation, the liver could have lost its ability to withstand the long length of deprivation. The linear increase in the relative heart weight as water deprivation increased agrees with Viola et al. [2]. A probable explanation for the finding could be that during water deprivation, the heart supplies not more than blood as a response to an increase in the size and weight of other internal organs, such as gizzard [12].

The positive linear relationship between water deprivation and lung weight could suggest the ability of the birds to maintain a water balance and BW dynamics through tissue synthesis and muscle development, including lungs [12]. The size of gizzard weight also increased with an increase in water deprivation time. The gizzard is expected to enlarge when the feed becomes hard to digest [13]. Broilers quickly adapted to the need for increased digestive capacity due to water deficiency. Due to a shortage in water, digest movement is expected to be slow, leading to the accumulation of feed in the gizzard, causing it to expand [12]. Chronic stress due to feed and water restriction compromises antibody production, thereby exacerbating susceptibility to viral infections [14].

The response of an increase in spleen weight of broiler chickens with increasing water deprivation could have been due to mechanisms that sought to increase the production of lymphoid tissue and evade risks posed by the reduced immune response, similar to Liew et al. [15]. The findings contradict Mahmood et al. [16] and Toghyani et al. [17], where nutritional stress was implicated in the reduced growth of organs and responses involved in the immune response. Even though there were no suspects of kidney failure in the current study due to water deprivation, it should be noted that several authors have associated water deprivation with renal failure, which leads to sudden death in broiler chickens deprived of water [18]. Such findings are corroborated by Chikumba et al. [19], who reported that continued water deprivation may lead to impaired renal function.

5 Conclusions

There was a quadratic decrease of WDM and CDM with water deprivation. Maximum water deprivation management of 4 h can be considered in broiler production systems to conserve water. The relative internal organ weights increased linearly with increasing levels of water deprivation.

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Acknowledgments

The authors acknowledge financial support from the UKZN Productivity fund P530 for funding the project. We also acknowledge the stuff at Ukulinga Research Farm Station for management of broilers.

Funding information: The authors wish to acknowledge the University of KwaZulu-Natal for sponsoring the study.
Author contributions: M. C. and A. M. conceived and designed the research. M. V. M., S. Z. N, and M. M conducted the experiments. M. V. M analysed the data. M. V. M wrote the first draft of the manuscript. All authors read and approved the manuscript.
Conflict of interest: The authors state no conflict of interest.
Data availability statement: The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

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Received: 2022-07-01

Revised: 2023-02-24

Accepted: 2023-02-27

Published Online: 2023-09-06

This work is licensed under the Creative Commons Attribution 4.0 International License.

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https://doi.org/10.1515/opag-2022-0184

Keywords for this article

birds; heart; liver; spleen; water security

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