Effect of citric acid and acetic acid on the performance of broilers

An experiment was conducted with commercial broilers to investigate the effects of feeding citric acid, acetic acid and their combination on their performance and to determine the economic competence of using citric acid and acetic acid in broiler rations. A total number of 108 one day old straight run broiler chicks were distributed to four dietary treatments i.e. 0 % citric or acetic acid (A) , 0.5% citric acid (B), 0.5% acetic acid (C) and their combinations 0.5% citric acid and 0.5% acetic acid (D). The birds were reared in cages. Body weight gains, feed conversion ratio (FCR), mortality, dressing yield and carcass characteristics were recorded. The performance showed significant increase in body weight gain (P<0.05) when compared with the control during 0-5 weeks of age on 0.5% citric acid (B). Feed consumption increased (P<0.05) at 2 and 3 weeks of age on 0.5% citric acid (B). Feed conversion was found higher (P<0.05) during 0-5 weeks of age in treatment B when compared to those of the other treatments. Carcass characteristics were not affected by dietary treatments. The highest mortality was found in treatment A and treatment C due to excessive hot. It may be concluded that use of 0.5% citric acid in the diet of broilers may have better performance in respect of live weight gain and feed conversion. Keyword: Acetic acid, Citric acid, Broiler performance


Introduction
The feed additives have a number of beneficial effects like control of pathogenic microorganisms and enhance the growth of beneficial microorganisms (Shane, 1999).Antibiotics possess these beneficial effects but their use in the poultry industry has been intensively controversial because of the development of bacterial resistance and potential consequences on the human health.So, the alternatives to antibiotics are researched.Among these compounds, organic acids are promising alternatives (Hyden, 2000).Health of the gut is one of the major factors governing the performance of birds and thus, the economics of poultry production (Samik et al., 2007) and the profile of intestinal microflora play an important role in gut health.Dietary organic acids and their salts are able to inhibit microbial growth in the food and consequently to preserve the microbial balance in the gastrointestinal tract.In addition, by modifying intestinal pH, organic acids also improve the solubility of the feed ingredients, digestion and absorption of the nutrients (Patten and Waldroup, 1988;Owings et al., 1990;Skinner et al., 1991;Adams, 1999).
Both, the feed industry and the poultry production sector, still suffer from huge losses due to the contamination of food with pathogenic bacteria and their related impacts in the animal, such as lower weight gains or even increased mortality.Poultry performance and feed efficiency are closely interrelated with the qualitative and quantitative microbial load of the host animal, including the load in the alimentary tract and in the environment.Organic acids like citric acid and acetic acid have been used in diets due to their positive effect on health and growth of bird.More recently, the ban on antibiotics as a growth promoter in the European Union and the resulting pressures on meat exporters around the world, have increased interest in organic acids to attain performance improvements in growing swine and poultry.As the uses of organic acids are becoming more acceptable to feed manufacturers, poultry producers and consumers, there is a growing interest in substituting them for antibiotic as growth promoters (Callsen, 1999).Citric acid and acetic acid are used as the substitute of antibiotic growth promoters in many countries of the world (Estieve et al., 1997).But use of citric acid and acetic acid as substitute of antibiotic growth promoter in Bangladesh is a new phenomenon.The effects of citric acid and acetic acid as substitute of antibiotic have not yet been evaluated much under Bangladesh condition.Therefore, the present study was undertaken to evaluate the effect of feeding citric acid and acetic acid and their combination on the performance of broiler and to determine its economic impact in broiler production.

Materials and Methods
The experiment was conducted with 108 one day old straight run broiler chicks (Hubbard Classic) for a period of 35 days.The chicks were randomly divided into 4 equal treatment groups (A, B, C and D) each having 27 chicks.Each treatment was subjected to 3 equal replications of 9 chicks each.The diets were formulated with commonly available feed ingredients is shown in Table 1.The dietary treatments were A (control diet) and B, C and D were supplemented with 0.5% citric acid, 0.5% acetic acid and 0.5% citric acid + 0.5% acetic acid respectively with drinking water.Dry mash feed was supplied on adlibitum basis.Fresh clean drinking water was made at all the times.Adequate sanitary measures were taken during the experimental period.The birds were housed in cages of 120cm × 76cm.Calculated according to Wiseman (1987) At the age of day 4 and 14, birds were vaccinated against Infectious Bursal Disease (IBD) using Bursine-2.Chicks were also vaccinated with B.C.R.D.V on 8 th day.To evaluate the treatment effect, weight gain, feed conversion ratio, mortality, dressing percentage, economy of broiler production were recorded and calculated.At the end of experiment, two birds from each treatment were selected randomly to record the dressing yield, organs weight and cut up parts.Feed samples were analyzed for dry matter (DM), crude protein (CP), ether extract (EE), crude fiber (CF), nitrogen free extract (NFE), and total ash by following the method of AOAC (1990).Duplicate samples were analyzed and the average value was taken.Collected and calculated data were analyzed for analysis of variance (ANOVA).The significant differences were identified by LSD among the treatments.

Body weight gain
Effect of organic acids inclusion in broiler ration on live weight gain is presented in  et al. (1992) where improved weight gain was observed with administration of citric acid in diets at 0.3, 0.5 and 0.7%, respectively.The results contradict with the findings of previous researchers Pinchasov et al. (2000) where depressed weight gain was observed with application of acetic acids in diets.

Feed intake
The average feed intake of birds fed on different diets is shown in Table 3.It is evident that average feed intake was lower in treatment A and higher in treatment D and differed statistically (P<0.05)only at 2 nd and 3 rd week of age.These results contradict with the finding of previous researchers (Darko et al., 1991;Frigg et al., 1983 andStipkovits et al., 1992) where depressed feed intake was observed.During (0-4 weeks) of age feed intake was the highest in treatment B (1787.00g) and the lowest in treatment C (1681.00g).During (0-5 weeks) of age feed intake was the highest in treatment B (3118.56g) and the lowest in treatment A (2913.16g) but difference was non-significant (P>0.05).The lower feed intake in treatment C was accompanied by retarded growth to be the consequence of depressed water intake by the application of acetic acid in water.

Feed conversion
The effect of organic acid supplementation on feed conversion is presented in Table 4.It is evident that FCR differ significantly (P<0.05)among treatments at all ages.Better feed conversion was found in treatment B and lower in treatment C during 0-5 weeks of age.The highest feed conversion on the administration of citric acid was in agreement with the findings of Afsharmanesh et al. (2005) who found higher feed conversion with the administration of citric acid in poultry.

Organs weight
It is evident from the Table 5 that dressing percentage for treatment A, B, C and D were 54.98, 55.40, 51.90 and 56.80 % respectively which did not differ significantly (P>0.05).The results are in well agreement with the previous findings (Kahraman et al., 1997) where no significant effect was observed.The highest (56.7%) value for carcass yield was found in treatment D and the lowest (51.8%) value was found in treatment C. In dietary treatment D the dressing yield was improved by about 3.46 % when compared with the control group.This result did not agree with previous findings of Garcia et al. (2000) who found decrease carcass yield.The increased dressing yield on dietary treatment D might be due to increasing live weight on 0.5% citric and acetic acid.The result partially agreed with Sapra and Mehta (1990), who found increased edible meat yield with increasing body weight.Per cent giblet weight was not affected by dietary treatments.Weight of shank in different treatments did not differ significantly (P>0.05)among different dietary treatments.Head weight was similar in all treatments.Skin and feather weight per cent did not differ significantly (P>0.05)among treatments.

Economy of broiler production
The production cost of broiler in different dietary treatments is shown in ; B= Control diet + 0.5% citric acid; C= Control diet + 0.5% acetic acid; D= Control diet + 0.5% citric acid + 0.5% acetic acid; ±= Standard deviation; SEM= Standard Error Mean; Figure having different superscript in the same row differ significantly (P<0.05);*= 5% level of significance

Table 2 .
Significant (P<0.05)difference in body weight of birds among the groups were observed at all ages.Birds on treatment C showed lower (P<0.05)weight gain than control group (A) and treatment B showed the highest (P<0.05)weight gain.Treatment D showed improved growth when administration of both citric acid in diets and acetic acid in water was done together.
Shen-HuiFang et al. (2005);reatment C seemed to be a consequence of a depressed water intake induced by application of acetic acid in water.The result is in agreement withSchuhmacher et al. (2006), who found lower weight gain.Highest weight gain on 0.5% citric acid agreed with previous findings ofShen-HuiFang et al. (2005); Denil et al. (2003)and Stipkovits

Table 6
Net profit per kg live broiler was the highest in treatment A (Tk. 19.70) followed by treatment B (Tk 19.30), C (Tk.10.70) and D (Tk.16.20) respectively.The highest total net profit was observed in dietary treatment B and the lowest total net profit was observed in treatment C as compare to treatment A (Control group).

Table 6 . Production cost of broiler in different dietary treatments
A= Control diet; B= Control diet + 0.5% citric acid; C= Control diet + 0.5% acetic acid; D= Control diet + 0.5% citric acid + 0.5% acetic acid.NB-cost of feed calculated based on ingredients and test substances added. 1 Management cost assuming approximately 33% of total cost (except chick cost).