EFFECTS OF GUANIDINOACETIC ACID SUPPLEMENTATION IN BROILER CHICKEN DIET ON CARCASS CHARACTERISTICS

design (CRD) with four replicates. Carcass characteristics were determined in the laboratory by analyzing the (abdominal fat, tissue protein, tissue fat and pH). There were statistically significant effects observed on abdominal fat, body tissue protein and body tissue fat of the carcass. The study concluded that GAA supplementation increased carcass characteristics, and provided better economic returns. The study recommends utilization of GAA supplementation at level of 0.12% GAA/Kg for rapid growth of broiler, enhanced abdominal fat, body tissue protein, body tissue fat, and utilization of GAA for better economic returns to the farmers.


ISSN: 2320-5407
Int. J. Adv. Res. 9(07), 408-415 409 Most of the poultry industry aim at increasing the carcass yield and reduce carcass fatness especially abdominal since excessive fat in modern poultry strains has been one of the problems facing this industry [17]. In addition, excessive fat in modern poultry strains is a major problem facing poultry industry due to consumer's preference [17].This has made consumers have preferences in terms of carcass characteristics (fat levels) hence affects consumer acceptance, which the Kenyan meat production, processing and distribution sectors must make enormous efforts to satisfy.
Whilst the immediate effect of guanidinoacetic acid on poultry has been well documented, the effects of guanidinoacetic acid supplementation in broiler chicken diet on growth performance and carcass characteristics on boilers production is poorly understood. This therefore formed the rational of this study.Previous studies showed that GAA consumption reduced the amount of abdominal fat, which is directly correlated to the total body fat. Studies have shown that energy was deposited in the carcass of birds mainly as protein rather than fat during the early stages of chick's life [8], [12], [5].
Dietary supplementation with GAA resulted in a higher percentage of breast meat yields in the carcass [8].However, [10].reported that the main effects of GAA supplementation and energy levels on carcass traits were not significant, although addition of GAA significantly reduced the liver percentage. This study scrutinized boilers growth and their carcass characteristics to ascertain if GAA inclusive levels had any considerable effect. The main purpose being to determine the effect of dietary inclusion of Guanidinoacetic acid on carcass characteristics of broiler chicken.

Study Animals
A total of 240-day-old Cornish breed chicks were obtained from a reputable firm and kept under the deep litter system a vaccine of Newcastle and infectious bronchitis was given a drop per eye at 7 th and 21 st days while Gumboro vaccine through drinking water was given at 14 th and 28 th days of age.

Experimental Treatments, Study Design and Study Layout
GAA and feed ingredients used for formulating the experimental diets were bought from a reputable feed manufacturing firm. The experiment had six formulated treatments as shown in Table 3.1 and Table 3.2. The feed additive (GAA) was supplemented in diet 2 to diet 5 with diet 1 being the control. That is Diet (D1) was the control with no GAA, diet 2 (D2) was supplemented with 0.003% GAA/kg, diet 3 (D3) was supplemented with 0.006% GAA/kg, diet 4 (D4) was supplemented with 0.009% GAA/kg, diet 5 (D5) was supplemented with 0.012% GAA/kg, and diet 6 (D6) was supplemented with 0.015% GAA/kg. The treatments were laid down in a complete randomized design (CRD) in four replicates.
The birds were randomly allocated to the six treatments and housed in groups of 10 birds of 7 females and 3 males per pen in 24 pens. The experiment was divided into two phases which were growing phase from 1 st day to 21 st day (Table1) followed by finishing phase from 22 nd to 42 nd day (Table2). The chicks were fed on broiler starter mash for the first 21 days and broiler finisher for the last 21 days. The feeding trial experiment lasted for 42 days.
The birds were divided into 6 groups of 40 chicks were assigned the six treatments. Each group was further sub divided into four replicates of ten chicks per replica. The birds were weighed and placed in 24 well ventilated pens of 1 m X 1 m where they were reared for 42 days. The chicks were fed on broiler starter for the first 21 days and broiler finisher for the next 21 days. The floor of each pen was covered with wood shavings to a depth of about 6 cm and maintained dry. The temperature in each pen was maintained by infra-red lights at 26-36°C up to 14 days of age, and then it was eventually reduced to room temperature by adjusting the height of the bulb. During the entire period of the study, the lighting program was 24 hrs light with free access to feed and water. 100% 100% 100% D1= control with no GAA; D2= supplemented with 0.003% GAA/kg; D3= supplemented with 0.006% GAA/kg, D4= supplemented with 0.009% GAA/kg; D5= supplemented with 0.012% GAA/kg, and D6= supplemented with 0.015% GAA/kg.

Feed formulation
Two basal diets of broiler starter and broiler finisher diets were formulated basing on the Kenya Bureau Standards (KEBS) for nutrient requirements for broiler feeds [6].Maize grain and pollard were used as the main sources of energy while soybean meal, fishmeal and corn gluten meal were used as protein sources. Broiler starter diet had 3000 kcal ME/kg of feed, protein content of 220 g/kg (DM basis), 1% calcium and available phosphorus levels at 0.4% in the diets while lysine and methionine levels were 0.11 % and 0.05% respectively (Table 3). Broiler finisher formulated contained 3400 Kcal ME/kg of feed, protein content of 180 grams per kilogram feed, calcium, and available phosphorous level of 1% and 0.4%, respectively while lysine and methionine levels will be 0.09 % and 0.04% respectively (Table4; as per NRC, 1994). For each diet, all the ingredients were weighed and mixed for 45 minutes using a small feed mixer.

Animal health care
The chicks were vaccinated against Newcastle disease and Infectious bronchitis diseases (IBD) (B.NO :B1IBH20-004) at the age of 7 days and another repeat of Newcastle disease and IBD (B.NO :IN20-008 at 21 st days of age of a drop per eye. The birds through drinking water were also vaccinated against Gumboro at 14 th and 28 th days of age (B.NO Georgian strain BQ 3020). All vaccinations were followed with a vitamin boost for 3 days. The birds were monitored daily to assess their health in terms of their activeness during feeding, watering, and their behavioral aspect like posture and movement within the cage.

Chemical analyses of the formulated diets
The experimental basal diets were subjected to proximate analysis using [2]. procedures while the Calcium and phosphorus contents were determined using atomic absorption spectrophotometry and calorimetry, respectively.

Broiler performance
The body weight gain (BWG) of the chicks and the feed intake (FI) was recorded on a weekly basis. Feed intake was the difference between the cumulative daily feed offered and left over at the end of every week. Body weight gain was the difference in weight at the beginning and end of each week. The weekly performance of the two parameters (BWG and FI) for each replicate were summed up at the end of the starter and finisher phase to determine the changes in each phase. The means for the four replicates per treatment were used to compute the 412 treatment performance per bird in terms of body weight gain and feed intake. Feed conversion ratio (FCR) was determined as a ratio between feed intake and body weight gain at the end of each phase [16].

FCR = FI / ϪWG
The feeds were weighed in bulky every week and offered daily adlibitum. The amount of feeds consumed and the weight of each birds in the cage was taken weekly in the morning after feeds and water have been withdrawn.

Carcass characteristics
At the end of the study (42 days) two birds from each replica to make eight per treatment, were randomly picked and tagged. The birds were starved off feed for 12 hours but provided with drinking water. The selected birds were sacrificed and abdominal fat pad (an indicator of carcass fat content) from each carcass was removed and weighed using an electronic weighing scale, while fresh and the mean weight for each treatment recorded. The abdominal fat was calculated as a percentage of the final body weight and used as an indicator of carcass fat content. The breast meat from each carcass was cut off and used to determine postmortem pH, tissue protein %, and tissue fat %.

Statistical analysis
The collected data on feed intake, feed conversion rate, body weight gain, abdominal fat body tissue fat and pH was recorded in Microscoft excel 2008 and later was subjected to analysis of variance (ANOVA) using GenStat software 15 th edition. The level of statistical significance was preset at p ≤ 0.001. The mean separation test was determined using the Turkey HSD test procedures.

Effect of dietary inclusion of Guanidinoacetic acid on carcass characteristics of broiler chicken. Abdominal fat, body tissue protein, body tissue fat and pH
Results revealed that there was significant effects (P≤0.001) exhibited on abdominal fat, body tissue protein and body tissue fat of the carcass. However there was no significant effect on pH of the carcass Table 6. The lowest abdominal fat (13.1), body tissue protein (30.5%) and body tissue fat (9.33%) was obtained in 0.00%GAA/Kg. Results revealed that both abdominal and body tissue fat were significantly influenced by GAA and they were much lower than the recorded levels of body tissue protein. This finding corroborates with the findings of other researchers [8], [12], [5].whose studies showed that energy was deposited in the carcass of birds mainly as protein than fat during the early stages of chick's life. Generally, broiler chickens proportionally gain more carcass protein than fat in their early stage of growth. Inclusion of GAA in the feeds enhanced body tissue protein although the highest level 0.15% reduced it concentration. In this situation, it can be considered that the protein needs for optimum cell-mediated immune response may be reduced when diets contained optimum levels of GAA. Similar findings have been reported previously [9]. Also studies have suggested that GAA supplementation in feeds may spare arginine and help protein synthesis, which finally increases meat yield [3]. There were no significant differences exhibited in the pH. The findings differ with those of [9], who reported that dietary supplemental GAA significantly reduced pH of meat. Also [14]reported that increasing dietary supplementation of GAA could increase 413 the muscle pH value and water holding capacity in growing finishing pigs. This manifestation could be attributed to same muscle glycogen levels of the broilers at the time of slaughter which is known to determine the ultimate pH.
Carcass characteristicsresults revealed that significant effects was exhibited on abdominal fat, body tissue protein and body tissue fat of the carcass. The lowest abdominal fat (13.1%), body tissue protein (30.5%) and body tissue fat (9.33%) was obtained in 0.00%GAA/Kg.