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2008 - 200912010 - 20111
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Subject: Poultry Science × Author: SRILATHA, T × Type: Thesis ×
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    ThesisItemOpen Access
    EFFECT OF MICROBIAL PROTEASES AND CRITICAL AMINO ACIDS MODULATION ON THE DIETARY REQUIREMENT OF PROTEIN IN COMMERCIAL BROILERS
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2011-11) SRILATHA, T; RAVINDER REDDY, V(MAJOR); CHINNI PREETHAM, V; RAMA RAO, S.V.; RAMANA REDDY, Y
    ABSTRACT: Protein is the second largest nutrient which determines the feed cost of poultry production. By optimizing the nutrient allowances of dietary crude protein (CP) through supplementation of the most critical amino acids and supplementation of microbial proteases in at sub-optimal concentrations of dietary CP we can reduce the cost of feeding besides minimizing environmental pollution from broiler farming. To fulfill these objectives, a total of 5 experiments were conducted including an in vitro protein digestibility of compounded broiler feeds. All experiments were conducted with commercial broilers reared in battery brooders from 1 to 42 d of age. The primary objective of the Experiment 1 was to find out the optimum concentrations of CP in broiler diet during different phases i.e., pre starter (0-10d), starter (11-21d) and finisher (22-42d). Two levels of CP during pre starter (23 and 21%) and starter (21 and 19%) phases and three levels in finisher phase (19.5, 18 and 16.5%) were tested. The experimental design includes 2 x 2 x 3 levels of CP during pre-starter, starter and finisher phases respectively. The concentrations of lysine, threonine and tryptophan were maintained at the same ratio considering the ideal amino acid ratio (Baker 1996), except methionine which was maintained at 45, 45 and 38% of lysine during pre starter, starter and finisher phases, respectively. The results showed that the broilers fed low levels of CP ( 21 and 19 %) showed significantly higher body weight gain (BWG) and feed intake (FI), and better feed efficiency as compared to the diets with high levels of CP during pre-starter and starter phases (23 and 21%, respectively). The birds fed on higher (19.5%) level of protein in the finisher phase showed higher body weight gain and best feed conversion ratio (FCR) compared to the lower levels (16.5 and 18%). Carcass characters were not influenced by the variation in dietary CP level tested except the abdominal fat weight which was significantly higher in broiler fed low CP diet either all through 1 to 42 d of age or the lower levels of CP during starter and finisher phases compared to those fed higher levels of CP during all three phases. The results showed that the broilers fed low CP had significantly higher protein digestibility compared to the high CP fed birds. Experiment 2 was conducted to test the feasibility of further reducing the dietary CP below the optimum levels determined in Experiment 1, by modulating the levels of critical amino acids without affecting the broiler performance. The control diet (CD) formulated to contain optimum requirements of CP 21, 19 and 19.5% during pre-starter, starter and finisher phases, respectively. The optimum CP levels were further reduced by 1.5% in the basal diet (BD) during all the 3 phases (19.5, 17.5 and 18%, respectively), Four different concentrations of critical amino acids (lysine-Lys, methionine-Met, threonine-Thr and tryptophan-Try) were added to the diet containing sub-optimal levels of CP by maintaining constant ratio in relation to the dietary Lys level as detailed in Experiment 1. In addition to these levels, a diet with CP recommended by NRC was maintained. A diet with CP levels being followed by the broiler industry was maintained (23, 21 and 19.5% in PS, S and F diets respectively) as the reference diet (RD). The performance of broilers fed the CD (21, 19 and 19.5% CP, in PS, S and F, respectively) was similar to those fed the RD or NRC diet. Reduction of CP content by 1.5% (19.5 and 17.5%) than the CD decreased the performance as compared to those fed on CD during pre-starter and starter phases. But the reduced CP during finisher phase (18%) supported the BWG, which was statistically similar to those fed the CD. Increasing levels of critical amino acids (Lys, Met, Thr and Try) in the BD resulted in progressive and significant reduction in the performance. Broilers fed diet with sub-optimal CP had significantly higher abdominal fat compared to those fed with CD, RD and NRC diet. Supplementation of critical amino acids to the sub-optimal protein diet did not influence the abdominal fat deposition. Effect of supplementing three variants of protease (acid, neutral and alkaline) on in vitro digestibility of CP was tested with various graded concentrations of the enzyme in the Experiment 3.Results showed that the individual proteases at 66.66 u/g soybean meal / meat and bone meal had shown maximum protein digestibility. In the maize-soy bean based diets supplemented with alkaline protease had higher protein digestibility. Highest protein digestibility was observed in groups containing 2:1:1 (33.33:16.66:16.66 u/g diet) and 1:1:2 (16.66:16.66:33.33 u/g diet), acidic, neutral and alkaline proteases, respectively. In maize-soya – meat and bone meal based diet, supplementation with acidic (66.98%), alkaline (64.66%) and neutral (60.20%) proteases significantly improved the protein digestibility compared to the control group. Highest protein digestibility was observed in groups containing 2:1:1 (33.33:16.66:16.66 u/g diet) and 1:1:1 (22.22:22.22:22.22 u/g diet), acid, neutral and alkaline proteases, respectively. Based on the in vitro protein digestibility coefficients, 3 effective levels of proteases (2000, 4000 and 6000u/kg) were selected. These effective combinations and concentrations of proteases were supplemented to low CP maize-soybean based diet (1:1:2 and 2:1:1) in Experiment 4 and low CP maize-soybean-meat cum bone meal based diet in Experiment 5 (1:1:1 and 2:1:1) to find out the possibility of reducing the dietary CP (1.5%) below the optimum levels. The results of Experiment 4 showed that the broilers fed high protein diet (CD) had significantly higher BWG and FI as compared to those fed sub optimal CP diets (BD). The feed efficiency was not affected due to the treatments employed. Proteases (acid, neutral and alkaline) supplementation to the BD had no effect on the performance. The relative weight of abdominal fat was significantly (P<0.05) higher in low CP fed birds compared to those fed the CD, but proteases supplementation to BD did not influence the abdominal fat content. The results of Experiment 5 showed that the broilers fed CD had significantly higher BWG compared to those fed BD. Supplementation of proteases to the BD significantly improved the BWG and feed efficiency during 1-21 and 1-28 d of age, but not during the latter phase (35 and 42 d of age) of growth. The broilers fed on CD had significantly higher ready to cook and breast yields compared to those fed the BD or BD the protease supplementation. The relative weight of abdominal fat was significantly reduced in broilers fed with 1:1:1 (acidic, neutral and alkaline proteases) at 4000 u protease / kg diet as compared to BD. In conclusion, the overall picture of study suggested that the dietary CP levels could be reduced below NRC recommended levels by 2-4% in pre-starter, starter diets and to an extent of 0.5% in finisher diet provided that levels of critical amino acids are closely looked after. Addition of proteases to low protein diets did not influence the growth performance of broilers fed maize-soybean meal based diet but it had a significant positive effect on in young chicken fed on maize-soybean meal based-meat and bone meal based diets.
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    ThesisItemOpen Access
    EFFECT OF ALPHA-LIPOIC ACID AND VITAMIN E ON THE PERFORMANCE, ANTIOXIDATION AND IMMUNE RESPONSE IN BROILER CHICKEN
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2008-11) SRILATHA, T; RAVINDER REDDY, V(MAJOR); Qudratullah, S; Raju, M.V.L.N
    ABSTRACT : The present experiment was conducted to study the effects of graded levels of alpha-lipoic acid (0, 20, 40, 60, 80 mg/kg), vitamin E (10, 50 mg/kg) and their combination in a 5 x 2 factorial manner on the performance, antioxidation and immune response of broiler chicken. A total of 400 day-old male commercial broilers were divided into 10 treatment groups with 8 replications (5 broilers in each) and fed one of the test diets till 6 weeks of age (starter 0-4 weeks and finisher 5–6 weeks). Body weight gain of broilers was not influenced by inclusion of Lipoic acid during starter phase. However, lipoic acid at 80 mg/kg had significantly (P< 0.05) higher body weight gain during finisher phase and also in over all period. Supplementation of various levels of lipoic acid, vitamin E and their combination did not influence feed intake of broilers. The inclusion of lipoic acid did not affect the FCR of broilers in over all period. Vitamin E did not influence FCR in starter and finisher periods. However, vitamin E at 50 mg/kg improved FCR in the over all period. Combination of lipoic acid and vitamin E also did not affect the FCR in the over all period. Livability was not influenced. The dressing yields and weights of liver, heart and gizzard were not influenced by various dietary treatments, but vitamin E at 50 mg/kg significantly (P<0.05) increased gizzard weights compared to control. Supplementation of lipoic acid at various levels did not affect the abdominal fat deposits, except at 20 mg/kg where the abdominal fat content was significantly (P<0.05) lowered. Lipoic acid at 20 and 80 mg/kg had significantly (P<0.05) higher breast yield percent than control. Lipoic acid at 60 mg/kg had significantly (P<0.05) higher spleen weight than control. Weight of bursa was not influenced by the inclusion of lipoic acid. The level of Vitamin E did not influence the weight of spleen and bursa. The combination of lipoic acid and vitamin E level influenced the weight of spleen but not bursa. The humoral immune response to NDV at 28 days of age significantly (P<0.05) increased with the inclusion of lipoic acid at 20 and 80 mg/kg plus vitamin E 50 mg/kg than control. Similarly, vitamin E at 50 mg/kg significantly (P<0.05) increased HI titres compared to its lower level of 10 mg/kg. At the age of 42 days, HI titers were significantly (P<0.05) higher in all diets supplemented with lipoic acid than control. Cell mediated immunity in terms of CBH response was significantly (P<0.05) higher on diets that contained lipoic acid at 60 and 80 mg/kg than control. Similarly, vitamin E at 50 mg/kg also had significantly (P<0.05) higher CBH than vitamin E at 10 mg/kg. Combination of lipoic acid and vitamin E did not influence CBH. Supplementation of lipoic acid and vitamin E influenced the activities of lipid peroxidase. MDA levels were significantly (P<0.05) reduced on all dietary treatment groups compared to the control diet. Supplementation of lipoic acid in all dietary treatment groups increased glutathione peroxidase levels. RBC catalase levels significantly (P<0.05) increased on diets contained lipoic acid at 60 mg/kg. It is concluded that Lipoic acid at 80 mg/kg and Vitamin E at 50 mg/kg may be supplemented to the broiler diet for improved growth, antioxidant status and better immune responses.