Using sodium bentonite to reduce litter ammonia gas production and improve hen laying performance

C Ezenwosu, A E Onyimonyi, N W Anizoba, C M Ugwu, N S Machebe, M Yusuf¹ and R C Ezeokonkwo²

Department of Animal Science, Faculty of Agriculture, University of Nigeria, Nsukka
ezechigoziricele@gmail.com
¹ National Biotechnology Development Agency (North Central Zonal Centre of Excellent University of Jos)
² Department of Vet. Parasitology and Entomology, Faculty of Vet. Med, University of Nigeria, Nsukka

Abstract

The study aimed at using sodium bentonite to reduce litter ammonia gas production and improve hen laying performance. A total of 180 (16 weeks) old noiler hens weighing 1700-1800 g at point of first of lay were allotted to 3 dietary treatments in a completely randomized experimental design with 5 replicates of 12 hens each. Treatments from 1-12 weeks of the feeding trial were as follows: NaB0=0 g sodium bentonite kg diet, NaB15 = 15 g sodium bentonite /kg diet and NaB30= 30 g sodium bentonite /kg diet respectively. Statistical analysis of data collected showed that dietary sodium bentonite caused significant effect (p<0.05) on egg weight, egg mass, yolk weight, yolk height, yolk diameter, albumen weight, albumen diameter, albumen height, albumen length, albumen ratio, albumen index, yolk ratio, egg length, egg width, shell weight and haugh unit and these parameters improved significantly (p<0.05) in favor of the treatment groups. Furthermore, percentage litter ammonia gas, moisture and pH reduced significantly (p<0.05) in favor of the treatment groups. In conclusion, dietary inclusion of sodium bentonite at 15 g/kg can be applied by egg producing farmers to reduce rate of litter ammonia gas production, improve egg quality and laying performance of hens.

Key words: ammonia, sodium bentonite, noiler, hens

Introduction

To reduce hunger and poverty facing the rising global human population are some of the 17 Sustainable Development Goals (SDGs) adopted in September 2015, by the United Nations (UN) member countries. Therefore, phenomenal investment in poultry production will help to reduce hunger and poverty which are currently ravaging the increasing human population globally. However, provision of sustainable source of farm animal protein to meet the protein demands of the rising global human population and attain self-sufficiency in animal protein supply calls for the production of all classes of poultry meat and eggs. According to FAO (2010), poultry sector is among the top sector that provides various sources of animal proteins for human utilization. Poultry are most inexpensive source of farm animal protein, contributing meaningfully to the rising demand for animal food products globally (Farrell 2013).

Despite the fact that poultry, can supply quality protein need of the growing human population, poultry is still faced with several environmental challenges such as ammonia gas production and its volatilization from the litter. According to Munk et al (2017) ammonia gas is a byproduct of bacteria degrading protein-rich substrates like animal dung. Accumulation of ammonia gas in poultry houses has been found to have a number of negative consequences on the environment, farm workers, and on health of birds (Salim et al 2014). Ammonia production is a normal part of poultry production, but when its production becomes high, it undermines the sustainable development of the industry and cause environmental pollution. Microbial degradation of ammonia by leads to the formation nitrous oxide which is a major greenhouse gas that contributes phenomenally to the global climate change. According to Zhou et al (2021) long-term exposure of farm animals to high NH ₃ production may lead to a reduced performance. Ammonia gas causes severe immune system deficiency especially in the first 21 days of bird's life (Shah et al 2020). According to Sheikh et al (2018) ammonia-induced ocular blindness, is particularly a harmful occurrence.

However, sodium bentonite as a cheap and easily available clay mineral compound can be applied by farmers as dietary additive to help curtail the rate of high ammonia gas emission during poultry production. Bentonite is a high-water absorption natural clay formed by the devitrification of volcanic ash (Moosavi 2017). According to Anonymous (1992), bentonite is composed of 75% or more clay minerals. Furthermore, sodium bentonite is a complex material that contains the following mineral compounds: SiO₂ 53.788 %, Al₂O ₃ 22.378 %, Fe₂O₃ 3.90 %, CaO 1.65 %, MgO 2.123 %, Na₂O 1.96 %, K₂O 0.693 % and organic matter 13.43% (Anonymous 1992). The use of sodium bentonite as a feed additive to enhance production performances, nutrient digestibility, and poultry health has been widely studied. Several studies have reported that bentonite has the potential to replace antibiotic growth promoters at an appropriate level due to its ability to bind to pathogenic bacteria, improve gut health, and increase digestive enzyme secretion (Mgbeahuruike et al 2021). Inclusion of clay mineral such as bentonite in the feed of farm animals can control the processes of feed digestion by increasing retention time of the digester along the GIT, thus permitting its greater digestion by enzymes absorption, and eventual enhancement of farm animal performance (Safaei et al 2014). From the study results of Subramaniam and Kim (2015), adding clays in the diets of farm animals might likewise bring about a rise in height of villus and also enhance height of villus to crypt depth ratio. This will eventually, bring an increase in the surface area of the GIT, thereby snowballing the digestibility of nutrient. Supplementation of 0.50 g/kg bentonite in the laying hen diet improved gut health and contributed to an increase in egg production (Chen et al 2020). Dietary bentonite can bind aflatoxins and eliminate their toxicity ( Mgbeahuruike et al 2021). Animal diet containing 15g and 30g/kg sodium bentonite has been shown to improve feed conversion ratio in birds (Safaeikatouli et al 2010). According to Nasir et al (2000) when bentonite was added to the diets of laying hens, egg production and egg size increased by 15% and 10%, respectively. Research has also shown that sodium bentonite as a clay mineral additive has a positive impact on the litter quality. According to Safaeikatouli et al (2011), on the 14th day of their study, the litter pH in the treatment group with 15g sodium bentonite kg ^-1 feed significantly decreased compared to control. The same authors also observed that treatments with 15 and 30 g sodium bentonite kg ^-1 feed significantly decreased litter moisture compared to the control treatment. The current study aimed at using sodium bentonite to reduce litter ammonia gas production and improve hen laying performance.

Materials and methods

The tested material (sodium bentonite) was obtained from its mining site in Imo State Nigeria. The sodium bentonite which was in a powdered form was kept at room temperature. Other feed ingredients were purchased from Hon. Peace Ugwu’s food stuff shop, Orie Orba, Nsukka, Enugu Nigeria

The study took place at avian research farm owned by the Department of Animal Science, University of Nigeria. From the report of the Department of Crop Science’s Metrological Center, University of Nigeria, Nsukka, annual rainfall of the study area ranges from 1567.05mm-1846.98mm. The feeding trial lasted for 12 weeks. Tables 1 show the compositions and calculated nutrients of the experimental diet.

A total of 180 (16 weeks) old noiler hens weighing 1700-1800 g at point of first lay were allotted to 3 dietary treatments in a completely randomized experimental design of 5 replicates of 12 hens each. Treatment were as follows: NaB0=0 g sodium bentonite kg diet, NaB15 =15 g sodium bentonite /kg diet NaB30= 30 g sodium bentonite /kg diet. Fresh drinking water and feed were provided continuously throughout the feeding trial. All the vaccinations and prophylactic treatments schedules for a healthy flock management and other management practices were followed.

Litter samples were collected from the surface to the down part of the litter in 4 locations to ensure proper sample representation in each replicate. The litter sample collected from the various points in each replicate were mixed together after collection to ensure homogeneity of samples. The litter samples after being collected with hand trowel, were put in a well labelled laboratory glass beakers and were carefully taken to the lab immediately for pH, and moisture analysis in every 4 weeks during the feeding trial. Percentage of litter ammonia gas analysis was done at the end of the feeding trial.

Concentration of litter ammonia gas in the entire litter samples collected (n=30) were evaluated by the application of Technicon Autoanalyzer using hypochlorite-indophenol procedure (AOAC 1990). The pH of the sample was determined using pH meter.

On the last day of every week throughout the feeding trial, 40 % of the total eggs laid by birds in each replicate were randomly selected for the determination of external and internal egg quality traits. Egg weights were measured using electronic sensitive scale of 6 kg capacity. Egg length and width were determined using electronic vernier caliper. Electronic scale was used for the measurement of shell weights after one day long drying at room temperature. Shell thickness was determined using electronic vernier caliper as follows: shell thickness = (thickness of blunt part + thickness of equatorial part + thickness of sharp part) / 3. Egg shape index (%) = (egg width / egg length) x 100. Haugh Units: HU = 100 log ₁₀ (H + 7.5 – 1.7W^0.37).

Albumen weight (g) = Egg weight – (yolk weight + shell weight). A sensitive electronic scale (0-6000 g) capacity was used to measure yolk weights after its separation from albumen using yolk separator. The height of albumen and yolk were measured using P6085 spherometer (tripod electronic micrometer) with 0.01mm accuracy in a flat dish. Yolk index (%) = (yolk height / yolk diameter) x 100. Albumen length, albumen diameter and yolk diameter were measured using electronic vernier caliper. Albumen index (%) = [albumen height / (minimal + maximal albumen diameter / 2)] x 100. Albumen ratio (%) = Yolk weight / albumen weight. Yolk ratio= (yolk weight / egg weight) x 100. Albumen ratio= (albumen weight / egg weight) x 100. Shell ratio= (shell weight / egg weight) x 100

Egg weights among the treatment were taken using electronic weighing scale of 0-6kg capacity

Egg mass = Per cent HDEP X average egg weight in grams/100

The Results obtained in the current study were analyzed based on a completely randomized design by ANOVA. Duncan’s multiple-range test(1955) was subsequently conducted when there was a significant difference among dietary groups. Data are presented as least squares means and standard error.

Results

Table 2 show the effect of sodium bentonite on % of litter ammonia gas production, moisture and pH. The percentage values of litter ammonia gas, moisture and pH at 0 g NaB/kg were the same (p>0.05), but significantly higher than the values recorded in 15 and 30 g NaB/kg.

Table 3 show the effect of sodium bentonite on laying performance of noiler hens. Egg weights and mass improved significantly (p<0.05) in hens on 15 and 30g NaB/kg compared to values observed for hens on control diet. values of hen day egg production among the treatment were not significant (p>0.05).

Table 4 show the effect of sodium bentonite on general external egg quality traits of noiler hens. Values of egg length, width and shell weight of hens on 0 g NaB/kg were lower than the values obtained for those on 15 and 30 g NaB//g diet. Values of egg shape index of hens on 0 g NaB/kg and 15 g NaB/kg were the same (p>0.05), but higher than the value recorded for those on 30 g NaB/kg diet. Values of shell thickness, shell ratio and haugh units were not significant among the treatments (p>0.05)

Table 5 show the effect of sodium bentonite on general internal egg quality traits of noiler hens. Yolk weight, albumen weights, albumen diameter, albumen length values of birds on 0 g NaB/kg were lower than the values obtained for those 0n 15-30 g NaB/kg. Yolk ratio values at 0 and 15 g NaB/kg were the same (p>0.05), but higher than the value observed for those on 30 g NaB/kg. Yolk/albumen ratio of hens on 15 and 30 NaB/kg were the same (p>0.05) lower than the value recorded at 0 g NaB/kg. Values of yolk height, yolk width, albumen height, yolk index, albumen index, and albumen ratio were not significant (p>0.05) among the treatments.

Discussion

The improvement in egg mass values of hens on 15 and 30 NaB/kg recorded in the current study were in comparable with the report that egg mass improved significantly by dietary inclusion of sodium bentonite (Gilani et al 2013; Yenice et al 2015). Also in a similar result, Gilani et al (2013) working on commercial Hy-Line W-36 hens from 51-63 weeks of age found daily egg mass improved in hens fed diet containing 10 g/kg sodium bentonite compared to control group. Even though hen day egg production values were not significant (p>0.05) among the treatments in the current study, but numerically, the treatment groups had higher values for hen day egg production. This was as a result of the dietary inclusion of bentonite that contains some minerals that improves egg production (Gul et al 2016). However, sodium bentonite is a multifaceted substance with percentages of the following compounds: Al₂O₃ 22.378%, K₂O 0.693 %, CaO 1.65 %, MgO 2.123 %, SiO₂ 53.788 %, Fe₂O₃ 3.90%, Na₂O 1.96% and organic matter 13.43 % respectively (Anonymous 1992). Also, clay groups contain anionic structure including alkali metal ions and trace elements, which are considered mineral supplies for animals (Suzanne et al. 2017) that promote egg production (Gul et al 2016). These trace elements and metal ions play crucial roles in egg production and improvement in egg quality. Metal ions act as cofactors (help molecules) which are required for the normal functioning of hormones and enzymes that maintain growth and egg production (Smith et al 2018). High levels of minerals such as calcium, iron, magnesium, iodine, zinc, and selenium that are found in bentonite enhance the creation of hormones and enzymes that supports production capacity of birds (Smith et al 2018). According to Saçakli et al (2015), the enhancement in egg weight as a result of sodium bentonite supplementation may be related to a reduction in feed transit along the gut which increased time for more feed digestion and thus, resulting to an increased nutrient absorption. According to Monks (1992) sodium bentonite absorbs fluid in the GIT of animals and thus, making the contents thickened and their movement slower along the intestines. This allows for more time for the animal to extract maximum nutrients from the feed that will eventually supports laying performance in hens. Increase in nutrient absorption such as energy, protein and linoleic acid have been proven as the most nutrients required for egg production and enhancement of egg weight (Godbert et al 2019). Bentonite was reported to improve health of gut in chickens as indicated by an increase in the villi height (Chen et al 2020). This is an indication of a greater luminal absorptive surface area for nutrients that brings improvement in laying capacity of hens. Research has shown that dietary bentonite enhanced intestinal health, which resulted in increased laying performance (Gul et al 2016; Chen et al 2020). It is therefore, scientific to conclude that the improvement in egg production in the current study can be related to improved energy and protein utilization brought about by sodium bentonite in the feed via extended feed passage time in the gut of hens on bentonite-based diets (Anonymous 1992). Bentonite is essential for reducing stress, improving liver function, and boosting lymphocyte growth (Kanana et al 2019). Reducing stress in laying birds as a result of bentonite supplementation will culminate into increase in egg production and quality. Egg shape index fall within the normal range of 72-76 among the treatments. Domestic hen eggs that are unusual in shape, such as those that are long and narrow, round, or flat-sided, cannot be placed in grade AA (nearly perfect) or A (slightly worse than AA) since an egg is generally oval in shape (72–76). Egg shape index are considered as sharp, normal (standard) and round if they have a shape index value of <72, between 72 and 76 and >76, respectively (Sarica and Erensayin 2004). Round eggs and unusually long eggs have poor appearances and do not fit well in egg cartons; therefore, they are much more likely to be broken during the shipment than the eggs of normal shape (Sarica and Erensayin 2009).

Internal and external egg quality traits improved (p<0.05) significantly in treatment groups compared to control group. The higher an increase in egg size will result to higher an increase in its length and width. Therefore, increased yolk and albumen quality may be connected to improved weight of eggs as observed in treated groups compared to control. It may be scientifically correct to assert that egg size or weight is positively correlated with its yolk, shell, albumen weights and height of its albumen, yolk and diameter of its yolk and albumen. In other words, large eggs present significantly greater yolk height, yolk diameter, yolk weight, albumen height, albumen weight and eggshell weight values than small eggs. In contrast results, Choi (2018) observed that 0.5 percent inclusion of bentonite in the diet of 74-week-old laying hens enhanced shell thickness.. Increased egg length and width in treatment group compared to control can be traceable to increase in egg size. This claim was supported by Nasir et al. (2000) who stated that sodium bentonite when added to the diets of laying hens resulted in an increased egg size by 15% and 10%, respectively. Even though the values of albumen height among the treatments were not significant, but numerically, treatment group had higher values The results agree with the report of Chen et al (2020) who stated that dietary montmorillonite greatly improved albumen height. Sodium bentonite in the diet of hen has positive effect of the egg quality due to its high mineral content, ion exchange capacity, and calcium affinity (Elliott et al 2019). According to Choi (2018) most important mineral content in sodium bentonite is calcium which promotes calcium absorption in hens and thereby leading to improvement in various eggshell traits as observed in the current study. Calcium is the main mineral component of eggshells and is also responsible for improving egg shell quality. Eggshell quality is a vital factor in egg production because large numbers of eggs with defective shells can lead to great economic losses. Treatment group improved (p<0.05) higher in egg shell weights. In the context of a farm, these improvement in shell quality in treated groups will prevent damaging of eggs during transport from farm to market compared to control group. Research has shown that dietary bentonite increases alkaline phosphatase that is responsible for bone mineralization and phytate degradation in the small intestine (Kriseldi et al 2021) and thus improving calcium and phosphorus availability used for eggshell formation. Calcium intake is the main factor that determines eggshell quality since the main component of eggshells is calcium with the composition of calcium carbonate (98.2%), magnesium (0.9%), and phosphorus (0.9%) (Shwetha et al 2018). In the current study, albumen and yolk quality traits improved higher in treatment group compared to control group. This was connected to high mineral content of sodium bentonite such as calcium. According to Qu et al (2018) dietary inclusion of silicate-based minerals increased yolk index. Calcium has a significant impact on egg albumen quality

Furthermore, improvement in egg quality and laying performance traits recorded in favor of the treatment groups in the present study could be linked to reduction in litter ammonia gas production during feeding trial (Table 2). Research showed that ammonia gas decreased egg production significantly for 7 weeks when hens were exposed to ammonia at concentration of 102 ppm (Charles et al 1966) and adversely affected egg quality (Cotterill and Winter, 1953). Laying performance and egg quality traits in hens can be negatively affected as a results of ammonia gas stress-inducing nature. This assertion was supported by Aziz and Barnes (2009), who found that broilers raised in environments with high ammonia concentrations had an increase in malonaldehyde levels in their blood (a key biomarker used to detect stress in farm animals) compared to control groups. Ammonia-induced oxidative stress can result in reduced egg production (St-Pierre et al 2003). Charles and Payne (1966) reared pullets in an ammoniated atmosphere from 11–18 weeks of age and observed that these birds tended to lay fewer eggs.. However, animal welfare scientists have therefore, emphasized the importance of enhancing litter conditions since litter is the major source of these odorous gases such as ammonia (Averós et al 2013). Control of pollutants such as ammonia gas is highly crucial during production since ammonia gas constitute a problem to farm animal production (Salim et al 2014). Dietary supplementation with bentonite has been shown to reduce the production ammonia gas by lowering some major culprits in ammonia gas production in the litter such as moisture and pH. Sanjay et al (2006) observed that ammonium ion, which is soluble in water transforms into ammonia gas in the presence of high litter pH. Ammonia volatilization can be decreased when the pH of litter is below 7, but noticeably elevated when the pH is over 8 (Reece et al 1979) and thus leading to poor productivity. However, Safaeikatouli et al (2011) observed that on the 14th day of their study, the litter pH in the treatment group with 15g sodium bentonite kg ^-1 feed significantly decreased compared to control. The same authors also observed that N ₂ content of broiler litter was significantly lower in treatment with 30g sodium bentonite kg ^-1 feed on 21st and 42nd day of feeding trials compared to the control and treatments with 15 and 30 g sodium bentonite kg ^-1 feed on 28th and 35th day significantly decreased litter moisture compared to the control treatment. Bentonite has the ability to absorb moisture in the digestive system in amounts many times bigger than their own weight, preventing it from remaining free in the excreta. Bentonite enhances consistency of chicken feces by lowering the rate of digester transit and colloid formation (Schneider et al 2017). Clay such as bentonite have been demonstrated to contribute to the reduction of other facility pollutants, including the volume of toxic gastrointestinal gases and off-site transport of odor (Slamova et al 2011).

Conclusion

• Sodium bentonite caused a significant effect on internal and external egg quality traits (yolk weight, yolk diameter, albumen weight, albumen diameter, albumen length, yolk ratio, egg length, egg width, shell weight, and egg shape index) and these values improved significantly in favor of the treatment groups.
  
  
• Laying performance values also improved significantly (p<0.05) in favor of the treatment group. Therefore, inclusion of sodium bentonite at 15g /kg can be applied to reduce rate o litter ammonia gas production, improve egg quality and laying performance in hens by egg producing farmers.

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