Nutritional Values of Red Pepper Seed Oil Meal and Effects of Its Supplementation on Performances and Physiological Responses of Broiler Chicks

Two experiments were conducted to evaluate the feeding values of red pepper seed oil meal (RPSOM) and to investigate its dietary supplementation on broiler performances. In Exp. 1, nutritional values of RPSOM were evaluated by analyzing chemical composition and determining true metabolizable energy (TME), nitrogen corrected TME (TMEn) and true available amino acid (TAAA). RPSOM contained 22.50% of CP, 4.75% of ether extract, 27.70% of crude fiber, 4.73% of crude ash and 49.97 ppm of xanthophylls. The contents of capsaicin and dihydrocapsaicin were 34 mg and 31 mg/100 g DM, respectively. The values of TME and TMEn determined by force-feeding 16 roosters were 1.73 kcal/g and 1.63 kcal/g DM, respectively. The average TAAA value of 17 amino acids was 85.22%. In Exp. 2, a total of 225 Ross male broiler chicks, 3 weeks old, were randomly divided into 9 groups of 25 birds each and assigned to three experimental diets containing 0 (control), 5 or 10% RPSOM fed ad libitum for 3 weeks. No significant differences were observed in growth performances and carcass characteristics. The level of serum cholesterol in the 10% RPSOM group was significantly lower than that of the control group (113.92 vs. 137.50 mg/dl). The dietary RPSOM at 5 and 10% levels increased the content of C18:2 ω6 in leg muscle compared with the control group. The results suggested that RPSOM can be included into broiler feed up to 10% without any negative effects on broiler performances and physiological responses and used as a non-conventional plant protein source, if its nutritional values are well evaluated. (


INTRODUCTION
Red pepper (Capsicum annuum L.) comes from fruits in the capsicum family, and intact or dried powder as well as seed oil is used to achieve the characteristically hot flavor of various cooking.The Korean red pepper is a key ingredient in many kinds of important Korean processed foods and recognized as the second most important agricultural product.There is 150,000-200,000 M/T of dried red pepper produced annually in Korea (Korean Ministry of Agriculture and Forestry, 2000).Red pepper seed oil meal (RPSOM), which is the high-protein residue obtained from oil extraction of red pepper seed, is receiving increased attention as a feed ingredient due to its abundance in this region.But it has not been fully utilized for feeding domestic fowls mainly because only limited information is available on RPSOM, especially its available energy and amino acids.Kim et al. (1999) reported that increasing levels of RPSOM in broiler diets resulted a slight decline in growth performances.The reason for the poor performance may be associated with the presence of anti-nutrient factors, the high fiber content in the meal, or low energy and amino acid availability or digestibility.It is recognized that information on the availabilities of energy and amino acids in feedstuffs enables more accurate diet formulation and a great control on diet quality (Green and Kiener, 1989).Fernandez et al. (1995) and Zuprizal et al. (1993) have been suggested that formulation of diets using vegetable protein ingredients with low quality on an available amino acid basis is superior to formulation on the basis of total amino acid content.It is desirable, therefore, that RPSOM be evaluated for its potential use as feed ingredient for poultry.This study was conducted to determine biological values of energy and amino acids in RPSOM.To investigate its feeding value, male broiler chicks were fed diets containing corn and soybean meal only (C-SBM control diet) or diets containing increasing levels of RPSOM from 5% to 10% that were formulated to be equal in ME value and available amino acids to the C-SBM control diet.

Analytical and digestibility evaluation of ingredients
RPSOM samples were first analyzed for DM, CP, ether extract, crude fiber, and xanthophylls by the methods outlined by the AOAC (1990).Capsaicin and dihydrocapsaicin were determined by HPLC (JASCO, Tokyo, Japan) as described by Saria et al. (1981).Amino acid contents in RPSOM were determined by amino acid analyzer (Hitachi Instruments Service Co., Ltd., Tokyo, 151, Japan) following hydrolysis in 6 N HCl for 22 h at 110°C (Spackman et al., 1958).Methionine and cystine were determined on samples that had been oxidized in performic acid prior to acid hydrolysis according to the method of Moore (1963).Chemical and amino acid compositions of RPSOM are shown in Table 1.For true metabolizable energy (TME) and nitrogen corrected true metabolizable energy (TMEn) assessment, Single Comb White Leghorn roosters were used.The assay was conducted as described by Sibbald (1979) with some modification.Following a 24h of feed withdrawn, twelve roosters were given 30 g of RPSOM via crop intubation.Four additional roosters were deprived of feed for 48-h period following the initial 24-h period.This group served as a control to correct for metabolic fecal and endogenous urinary losses.All excreta were collected for 48-h, and dried, lyophilized for determine gross energy by the adiabatic oxygen bomb calorimeter (1261 model, Parr Instruments Co., Moline, IL 65265).
The amino acid digestibility was measured using the same procedures as for TMEn assay.The TAAA values were determined and corrected for metabolic fecal and endogenous urinary amino acids, as described by Likuski and Dorrell (1978).This method is relatively rapid and less expensive than other procedures, and thus suited to the practical need for evaluation of feedstuffs in terms of amino acid potency.

Feeding trial
One-day old Ross male broiler chicks were fed commercial diets for 3 weeks post-hatching.Following an overnight period without feed, the chicks were randomly assigned into four groups such that the average body weights were similar for each group and fed one of three experimental diets (0, 5, or 10% RPSOM containing diet) for 21 days.The chicks were raised in a temperaturecontrolled windowless house under continuous lighting.The RPSOM containing test diets were formulated to be equal in the contents of true available lysine and sulfur containing amino acids to those of the C-SBM control diet (19% CP; 3,190 kcal TMEn/kg) and all diets were formulated to meet or to exceed the recommendation of NRC (1994).All the chicks were provided free access to feed and water.Room temperature was maintained at 25±3°C and 23/1 h light/dark cycle was kept throughout the experimental period.Animal facilities and husbandry were similar to conditions described by An et al. (2003).Feed intake and body weight of each group were recorded weekly.
At the end of experimental period, 10 chicks from each group were randomly selected.The blood was drawn from wing vein using sterilized syringes for determination of the various blood profiles.The concentration of total cholesterol was estimated according to the colorimetric method using cholesterol diagnostic kit (Cholesterol E kit, Youngdong Medical Corporation).The activity of glutamicoxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) were also estimated according to the colorimetric method GOT-GPT assay kit (BCS GOT-GPT assay kit, Bio Clinical System Corporation), following the manufacturer's direction.
The total lipid of leg muscle was extracted with a mixture of chloroform and methanol (2:1, v/v) by the method of Folch et al. (1957).Lipid extracts obtained were methylated according to the methods of An et al. (1995) with some modification.Fatty acid methyl esters were extracted with hexane and measured by gas-liquid chromatography (HP 5890 II Series, Hewlett-Packard, Atlanta, USA) using 0.32 mm I.D.×60 m capillary column (SUPELCOWAX-10, Supelco Ltd., Pennsylvania, USA).The initial column temperature was programmed at 150°C and increased to 220°C at 4°C/min.The injector and detector were set at 250°C and 260°C, respectively.The peaks were identified by comparison with standard mixture of fatty acid methyl esters (Lipid standard, Sigma Ltd., St. Louis, USA).Fatty acid composition of free fatty acid fraction was expressed as a weight percentage of total fatty acids.
The main effects between treated groups were subjected to ANOVA using the GLM procedure of SAS (2002), and significant differences were determined using Duncan's multiple range test at the level of p<0.05 (Duncan, 1955).Percentage data were transformed to arc sine percentages before square root percentages ANOVA was performed.

RESULTS AND DISCUSSION
According to the chemical analysis, RPSOM contained 22.50% of CP, 4.75% of ether extract, 27.70% of crude fiber, 4.73% of crude ash and 49.97 ppm of xanthophylls and is comparable with the values reported by RDA (1988).The contents of capsaicin and dihydrocapsaicin are 34 mg/100 g and 31 mg/100 g on DM basis, respectively (Table 1).Kim et al. (2002) were reported that the amounts of capsaicin and dihydrocapsaicin in various Korean red pepper powders were 41.54±33.42mg/100 g and 31.66±25.19mg/100 g, respectively.The ratio of capsaicin and dihydrocapsaicin in RPSOM used this study was 1.10 and this ratio is similar to the data reported by Ku et al. (2001) with ratio of 0.97 to 2.12.
The TME and TMEn, and TAAA values determined in roosters for RPSOM are presented in Table 3 and 4. The TME and TMEn values were 1.73 kcal/g and 1.63 kcal/g on DM basis, respectively.The TAAA of lysine, methionine and threonine were 85.75%, 87.55% and 82.73%, respectively.TAAA values, except for histidine, ranged from 81.17% to 94.89%.The average TAAA value of 17 amino acids was 85.22%.The mean TAAA values reported for herein were slightly lower than those values for soybean and sunflower meals as obtained previously (Green and   Kiener, 1989).It was postulated that the lower values of TMEn and TAAA were attributed to higher quantities of crude fiber (27.70%) in RPSOM.
Growth performances are shown in Table 5.The average feed intake of treated groups was slightly higher than that of the control, but not significantly.Body weight gain of the 5% RPSOM diet group was slightly greater as compared to that of control group.There was no significant difference in feed conversion rate between the control and treated groups.Some studies showed a slight decline in performance with increasing supplementation of RPSOM in diets for broiler chicks (Kim et al., 1999).The reason for the poor performance may be associated with the presence of anti-nutrient factors, the high fiber content in the meal, or low energy and amino acid availability or digestibility.From the results shown in Table 5, the growth performances in chickens fed diet containing 10% RPSOM were as good as those of C-SBM control diet group.This indicates that RPSOM could be replaced corn and soybean meal at 10% level on equal TMEn and available amino acid basis in diets of broiler chickens.In this study, it has been confirmed that feed formulation using bioavailability values, such as TMEn and TAAA, is an effective method for protecting the high variation in animal performances.Furthermore, the dietary capsaicin and dihydrocapsaicin might not cause antinutritional effect on the chicks in this experiment.
The levels of serum GOT, GPT and blood urea nitrogen were not affected by RPSOM feeding.Relative liver and abdominal fat weights (g/100 g BW) were also similar in all the dietary groups.Measurement of serum GOT and GPT activities indicative of liver damage in bird is a valuable tool to determine a safe inclusion rate for non-conventional feedstuff (Diaz et al., 2003).It was also observed that excessive inclusion of crambe meal, a locally produced non-conventional feedstuff, resulted in elevation of serum GOT level (Kloss et al., 1996).RPSOM appeared safe at an inclusion rate of 10% and will be recommended at this point without having adversary effect on physiological status.
RPSOM feeding at level of 10% resulted in a significant decrease in serum total cholesterol than that of control as shown in Table 6.Dietary capsaicin and dihydrocapsaicin have been reported to reduce the level of serum cholesterol in experimental animals fed cholesterol-enriched diets    (Negulesco et al., 1987;1989).It has been referred to decreased cholesterol synthesis, increased cholesterol excretion, or both as possible mechanisms with respect to reduction in blood cholesterol level.Srinivasan and Sambaiah (1991) reported that red pepper could stimulate the conversion of cholesterol to bile acids, an important pathway of excretion of cholesterol.Further study is required to clarify dietary RPSOM on tissue cholesterol metabolism.
The levels of C18:2 ω6 and total polyunsaturated fatty acid in the leg muscle of chicks fed 10% RPSOM were significantly increased compare to those of control group (Table 7).The dietary RPSOM at 5 and 10% levels increased the rates of total ω6 and total polyunsaturated fatty acids than that of control group.It is assumed that preformed C18:2 ω6 in RPSOM is effectively deposited into chicken meat.
In conclusion, RPSOM can be used for broiler feeds to 10% without any significant negative effects on broiler performances, and replaced corn and soybean meal on equal TMEn and available amino acid basis in diets of broiler chickens.

Table 1 .
Chemical and amino acid composition of red pepper seed oil meal 1

Table 2 .
Ingredients and chemical composition of experimental diets 1

Table 3 .
Energy values of red pepper seed oil meal (dry matter 1 Values are presented means±SE.

Table 5 .
Dietary effects of red pepper seed oil meal supplementation on growth performances and carcass characteristics in broiler

Table 6 .
Dietary effects of red pepper seed oil meal supplementation on blood profiles in broiler chickens1, 2

Table 7 .
Dietary effects of red pepper seed oil meal supplementation on the fatty acid composition of leg muscle1, 2