Relationship between Starch and Amino Acid Levels of Broiler Diets on Growth Performance and Feed Efficiency

Feed efficiency aims to achieve production results that match genetic potential with low feed costs and reduce the potential environmental pollution caused by excess nutrients which are not digested by livestock, especially proteins. One technique to improve feed efficiency is to use the concept of balance energy and protein in broiler feed formulation. In addition, protein is composed of amino acids with a certain ratio of the amino acid lysine (ideal protein concept model). Starch is a part of carbohydrate as important energy source for broiler chickens. The amount of starch is still not taken into account in predicting the energy content of a material. Starch provides a more than 50% of energy requirement in broiler feed which based on corn and soybean meal. Is generally assumed to be very high starch digestibility close to 100%, but the rate of degradation in the intestine varies [1].


Introduction
Feed efficiency aims to achieve production results that match genetic potential with low feed costs and reduce the potential environmental pollution caused by excess nutrients which are not digested by livestock, especially proteins. One technique to improve feed efficiency is to use the concept of balance energy and protein in broiler feed formulation. In addition, protein is composed of amino acids with a certain ratio of the amino acid lysine (ideal protein concept model). Starch is a part of carbohydrate as important energy source for broiler chickens. The amount of starch is still not taken into account in predicting the energy content of a material. Starch provides a more than 50% of energy requirement in broiler feed which based on corn and soybean meal. Is generally assumed to be very high starch digestibility close to 100%, but the rate of degradation in the intestine varies [1].
Feed with the starch content gradually broken down in the small intestine, will provide continuous glucose into the bloodstream. Glucose in the blood will be responded by the release of the hormone insulin. Insulin plays an important role in the transport of glucose and protein into muscle deposition during growth [2]. Continuous availability of glucose to the posterior part of the small intestine could prevent the use of amino acids as an energy source for the intestinal wall [3].
This study focused on investigate concept of balance energyamino acid related to the difference in the speed of starch digestibility in the small intestine Availability of different amounts of starch in the isocaloric feed in intestine, is expected to give different growth responses in broilers.

Animal and Housing
In this study, 240 birds (DOC) placed in to 24 pens. Six types of feed with four replication each replication contained 10 birds. Age 0-18 days use the same feed that kind of starter feed. Age 19-35 days used grower feed.

Diets
There are 6 types of feed formulations were used, which are 2 of the content of starch (high starch 36% and lower starch 32%), which combined with 3 levels of the amino acid Lysine-based Total 1.34%, 1:43%, 1:48% for the starter phase, and 1.18%, 1.3%, 1.35% for the grower phase. Other amino acids will follow the ratio of the total Lysine according to nutrient requirement ROSS 308. Prediction systems for nutrient content of raw materials using SFR (Schothorst Feed Research) system with Format International Formulation Software from England.
The feed is given in the form of crumble, with a minimum temperature of 80 o C conditioner, die size of 3.2 mm, minimum 90% PDI. Composition and nutrient content of research feed as in Tables  1 and 2.

Feed quality and blood parameters analysis
• Proximate analysis: Quality feed were analyzed using full proximate AOAC method (1980 • Total protein digestibility (%): calculated by subtracting the total protein consumed by the amount of protein remaining in the feces, divided by the total protein consumed multiplied by 100%.

Chicken growth
• Feed intake (g/bird): measured by weighing the amount of feed consumed during the study.
• Average weight gain (g/bird): calculated by calculating the weight by the end of the study reduced the initial weight.
• Feed Conversion Ratio: calculated by comparing feed consumption with weight gain.

Statistical Analysis
The experimental design used in this study is completely randomized design (CRD) with 4 replications 2x3 factorial. The data obtained were analyzed using analysis of variance (ANOVA), the differences among mean treatments were analyzed using Tukey test [4].

Weight gain
Based on Table 3, the average weight gain of birds aged 0-35 days in all treatments ranged from 1659.82-1891.54 gram. Potential genetic of modern broiler strain ROSS for weight gain in 35 days old is 1979 gram. Best result in this study was 95.5% of genetic potential.
Different starch content in feed between 36% and 32% gave a significant influence on the weight of the chicken 0-35 days (P<0.01). Weight gain was not influenced by difference levels of amino acids. The results showed no interaction between level of starch and amino acids on chicken weight gain. Feed with starch content of 36% led to  higher feed intake than the diet feed containing 32% of starch (P<0.05). Difference in feed intake is causing different starches consumption. Starch is part of energy source carbohydrate which is essential for broiler. Starch broke down into glucose in small intestines. Pancreatic α-amylase secreted into the lumen of the small intestine, especially in the jejunum to break the bonds α-1,4 starch.
Glucose is absorbed through the small intestinal wall, through sodium and potassium pump mechanism. Glucose is needed as a precursor in the citric acid cycle (citric acid cycle). Oxidation of glucose produces energy which is necessary for the synthesis of glycogen, amino acids, fatty acids and other metabolites. Feed that containing 36% starch produces more glucose compared with the diet containing 32% starch. This evidenced by the digestibility of starch in the small intestine (ileal Digestibility starch) were significantly different (P < 0.05), ie 99.46% and 99.26% between diets with a high starch compared with lower starch diet. Glucose produced of feed containing different starches will be determined by the amount of starch entering the small intestine multiplied by it digestibility level.
Feed with adequate starch content, will provide continuous glucose into the bloodstream. Glucose in the blood will be responded by the release of the insulin hormone [5]. Insulin plays an important role in the transport of glucose and deposition protein into muscle during growth [2]. Black et al. [6] stated that the unequal rate of starch digestibility and protein affect protein deposition and broiler performance.

Consumption and Feed Conversion Ratio
Based on Table 3, the average feed consumption in chickens aged 0-35 days all treatments ranged from 2795.76 -3199.32 gram. Genetic potential of modern broiler strain ROSS for feed consumption to 35 days old is 3248 gram. Average feed intake in this study was 90.9% of genetic potential. Starch content in different feed between 36% and 32% gave significant effect on feed consumption of chicken 0-35 days age (P>0.05). Feed consumption is not influenced by differences in the levels of amino acids in the diet. The results showed there is no interaction between level of starch and amino acids on broiler feed consumption. Differences on starch content in the diet cause differences gelatinization process at the pellet-making process heating steam temperature above 80 o C, leading to differences resistance pellet. Pellet quality was also influenced by the feed composition. A good quality pellet and not easily destroyed is one of the things that led to increased feed intake [1].
Feed conversion 0-35 day old chicks in all treatments ranged between 1.65-1.75. Genetic potential of modern broiler strain ROSS for feed conversion for age 35 days is 1.607. Average feed conversion in this study was 95% of the genetic potential. Starch content in different feed between 36% and 32% had no real effect on 0-35 days age chicken feed conversion (P<0.05). Feed conversion is not influenced by differences in the levels of amino acids in the diet. The results showed no interaction between level of starch and amino acids to the broiler feed conversion. Feed containing higher starch tends to provide a better feed conversion ration compared with lower starch content is 1.66 and 1.69.

Ileal starch digestibility
Based on Table 4, the average digestibility of starch in the small intestine 35 days old chicken on all treatments ranged from 99.09 -99.48%. Starch content in different feed between 36% and 32% gave significant effect on digestibility of starch in the small intestine of chicken 0-35 days (P<0:05). Digestibility of starch in the small intestine is not influenced by differences in the levels of amino acids in the ration. The results showed no interaction between level of starch and level of amino acids for starch digestibility to the small intestine for 35 day old chickens. Feed containing higher starch provides a higher digestibility of starch in the intestine than the lower starch diet containing (99.46% and 99.26%).

Total protein digestibility
Based on Table 4, the average of total feed protein digestibility of  chickens aged 35 days on all treatments ranged from 68.98 -84.22%. Starch content in different feed between 36% and 32% gave real effect on protein digestibility chicken feed 0-35 (P<0:05 ). Protein digestibility is influenced by differences in the levels of amino acids in the diet (P < 0:05). The results showed no interaction between level of starch and level of amino acids for protein digestibility. Feed containing higher starch gives a lower protein digestibility than the diet containing lower starch (75.35% and 84.22%). Results of this study indicate that although feed with low starch content have higher protein digestibility, but did not give weight gain better than the feed that contain more starch. Selle et al. [7] states that the rate of absorption of amino acids associated with the rate of starch digestibility and absorption of glucose that had effect on the growth and deposition protein. Nitrogen Retention not correlated with the rate of nitrogen digestibility

Content of Glucose, Uric Acid and Insulin in Chicken Blood
Blood glucose levels ranged between 200.14 mg/dl -223.68 mg/ dl. Hazelwood [8] stated that the levels of glucose in broilers is higher compared with other mammals, the range 180-250 mg/dL. Chickens in a state of hypoglycemia when blood glucose levels 137 mg/dL and hyperglicemia on blood glucose levels 363 mg/dL [9]. Results showed no significant differences in all treatments. Feed containing higher starch tend to have higher blood glucose levels compared with a diet containing a low starch content (214.97 mg/dL and 206.21 mg/dL). Blood glucose always regulated in relatively constant levels through glucoregulation mechanism which is controlled by several metabolic hormones such as insulin, glucagon, pancreatic polypeptide, corticosteron and thyroxin [9]. Levels of insulin in the blood of chickens significantly influenced by the levels of starch and amino acids in the diet (p < 0.05). Interaction between starch content and amino acids in the diet did not affect the levels of insulin. It showed that glucose results from breakdown of starch in diet stimulating secretion of insulin hormone by the pancreas [5]. Difference in starch content in feed will also result in different amounts of glucose. Grizard et al. [10] stated that insulin plays a role in protein deposition in the body. This is thought to cause better weight gain on diet containing more starch. Adding of the amino acid from Lysine 1:34% to 1:43% did not respond higher insulin levels, both on the high starch and lower starch diet. Uric acid level in the blood can be used as one indicator to the final result nitrogen metabolism Hartman et al. [11].
Donsbough et al. [12] stated levels of uric acid in broilers in the range of 2:02 mg/dL -5:13 mg/dL. The result of this study shows that differences in the levels of starch and amino acids in the diet treatment did not affect the levels of uric acid in the chicken blood. The result of this study similar to that expressed by Donsbough et al. [12]. Levels of uric acid had a tendency to increase at each addition of acid amino. Xie et al. [13] suggest that increased levels of uric acid by the addition of amino acids methionine in diet. Uric acid as an antioxidant stated by Hare and Johnson [14], therefore its existence is also associated with a state of oxidative stress [15]. Uric acid levels increase when the nitrogen intake increased Hevia and Clifford [16].

Conclusions
Diet containing the same type starch but with different numbers gives different of weight gain and feed consumption in broilers ages 35 days. Feed containing high starch tends to have more levels of glucose and insulin in the blood. Total digestibility of proteins not directly describes the growth performance of chickens on feed which the starch content distinguished.

Recommendations
Broiler feed formulation needs to pay attention to the content of starch in the ration, because the process of starch digestion and glucose absorption associated with protein deposition.