Effects of Lactobacillus cultures on growth performance, xanthophyll deposition, and color of the meat and skin of broilers

©2009 Poultry Science Association, Inc.

Effects of Lactobacillus cultures on growth performance, xanthophyll deposition, and color of the meat and skin of broilers N. H. Zhu,*† R. J. Zhang,*‡1 H. Wu,† and B. Zhang†

Primary Audience: Nutritionists, Researchers, Production Managers SUMMARY Two experiments were carried out to investigate the effects of Lactobacillus culture (LC) on growth performance and color of the meat and skin of broiler chickens. A total of 362 oneday-old Arbor Acres broilers were allocated to 7 treatments, with 7 strains of LC in experiment 1. The results showed significant differences in the color of shank skin and the growth performance of starter broilers among dietary supplements with different strains of LC. The effect of LC on xanthophyll deposition and color of the meat and skin of birds was evaluated with 1 strain of Lactobacillus MA (Lactobacillus salivarius) in experiment 2. A total of 208 one-dayold male Arbor Acres broiler chicks were randomly allocated into 4 treatments with 4 replicates each (13 birds per pen). Birds were fed a basal diet supplemented with 0, 0.1, 0.5, or 2.5% of L. salivarius cultures (LSC) from d 1 to 42. The results showed that Roche color fan scores of the shank skin were significantly increased at d 21 and 42 (P < 0.001) for chickens fed LSC. Xanthophyll content in the shank skin of birds provided feed supplemented with LSC was increased to 2.12 and 1.84 μg/10π mm2 from 0.95 μg/10π mm2 of the control group (P < 0.001). Yellowness (b*) values for thigh meat color were significantly increased for birds fed LSC (P < 0.05). It was concluded that dietary supplementation with LC increased the xanthophyll concentration in tissue and the Roche color fan scores of the shank skin of chickens. Key words: Lactobacillus culture, xanthophyll, shank color, broiler 2009 J. Appl. Poult. Res. 18:570–578 doi:10.3382/japr.2009-00012

DESCRIPTION OF PROBLEM The visual appearance of food, including color, is a major concern among consumers in the marketplace. Skin and meat color are considered a major quality issue in the consumers’ 1

Corresponding author: [email protected]

final evaluation of poultry products in China and in many other countries [1, 2]. Myoglobin content in muscles, a major factor contributing to meat color, is considered to be exclusively due to genetic factors [3, 4]. Carotenoids, such as xanthophylls, are compounds responsible for

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*Laboratory of Feed Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; †College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi 330045, China; and ‡State Key Laboratory for Animal Nutrition, China Agricultural University, Beijing 100193, China

Zhu et al.: LACTOBACILLUS CULTURES

MATERIALS AND METHODS Origin and Cultures of Lactobacillus The Lactobacillus cultures (LC) were identified as Lactobacillus plantarum (SRP, YJG), L. salivarius (MA), and Lactobacillus acidophilus

(LA, GA, SJ) by a biochemical test and via 16S rDNA sequencing analysis at the Institute of Microbiology, Chinese Academy of Science (Beijing, China). Six strains of Lactobacillus (SRP, YJG, MA, LA, GA, SJ) were isolated from the mucosa of the gut of healthy chickens and screened for probiotic properties. Preparation of LC de Man-Rogosa-Sharpe (MRS) broth was prepared with peptone (10.0 g/L), beef extract (8.0 g/L), yeast extract (4.0 g/L), glucose (20 g/L), K2HPO4 (2.0 g/L), ammonium citrate (2.0 g/L), sodium acetate (5.0 g/L), MgSO4 (0.2 g/L), MnSO4 (0.05 g/L), and Tween 80 (1.0 g/L), at a final pH of 6.0 ± 0.2. Collected colonies from a slant MRS culture were inoculated into the MRS broth and cultivated at 37°C for 48 h (anaerobic). The LC were stored at 4°C and mixed into the feed every 3 d. The viability of the bacterial cells was checked every other week to ensure that the concentration of the viable bacterial cells remained at 1 × 109 cfu/mL. Experiment 1 A total of 362 one-day-old male Arbor Acres broilers [21] were allocated to 7 treatments, with 4 replicates of 13 birds per replicate pen for each treatment. There were no significant differences in initial BW across treatment groups. The 7 treatments consisted of a control group (basal diet) and 6 groups of LC [the basal diet with the addition of 5 mL/kg of 1 strain of LC (SRP, YJG, MA, LA, GA, or SJ) every 3 d]. The viable cell count of the LC was above 1 × 109 cfu/mL. Nutrient concentrations of the basal diet (Table 1) met the minimum requirements according to the 1994 NRC [22]. Other antimicrobial agents and coccidiostats were not administered in the diets. Chickens were fed (ad libitum) a starter diet from d 1 to 21 and a grower diet from d 22 to 42, and were vaccinated for Newcastle disease and infectious bronchitis disease at d 1, 7, and 21. A 24-h light regimen was carried out during the first 3 d, and was changed to 23L:1D beginning on d 4. Mean air temperature of the bird chamber was approximately 35°C during the first week and was then decreased gradually to a constant temperature of 25°C at 3 wk. Feed

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the yellow skin color in broilers and are the most prominent source of pigmentation in poultry feeds [5]. Several synthetic colorants and natural source pigments, which have the disadvantage of being more expensive, have been used in feeds in China to give the finished poultry a desirable yellow color. The absorption and accumulation of pigment in broiler tissue have been shown to be altered by many factors, such as diet composition, disease, and parasitic infestations [6, 7]. Carcass color traits are also known to be affected by diets treated with probiotics [8, 9]. Strains of the genus Lactobacillus, which is the dominant genus in the small intestine of chickens early in life [10, 11], are the most widely used probiotic strains [12]. Many reports have shown that Lactobacillus administration increases villus height and digestive enzyme activities, enhances nutrient absorption, and thereby improves growth performance and FE [13–18]. Recently, researchers in our laboratory found that dietary supplementation of Lactobacillus, which was isolated from the digestive tract of healthy chickens, increased the Roche color fan (RCF) score for the shank skin of broilers [19, 20]. There is little published information regarding the effect of dietary probiotics on the absorption and deposition of dietary carotenoids and the color of chicken shank skin. In an attempt to obtain probiotic strains of Lactobacillus from poultry, we previously isolated Lactobacillus salivarius from the intestinal tract of chickens. The isolation showed a strong ability to attach to the intestinal epithelium of chickens and increased the RCF score of the shank skin [19]. Two experiments were conducted to study the relationship between Lactobacillus and xanthophyll deposition in broilers. The objective of this study was to investigate the effect of dietary supplementation of L. salivarius culture (LSC) on broiler performance, absorption, and accumulation of carotenoids in the skin and meat and on myoglobin concentration in the breast and thigh muscles of broilers.

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572 Table 1. Composition of the diets for broilers in experiments

Amount, % Item

Day 1 to 21

Day 22 to 42

1

56.60 36.00 3.00 1.80 1.40 0.35 0.20 0.15 0.50 2,950 21.35 1.18 0.52 0.90 1.02 0.45 10.2 to 11.3

60.00 32.50 3.50 1.70 1.3 0.30 0.10 0.10 0.50 3,000 19.53 0.98 0.44 0.78 0.93 0.35 12.2 to 13.4

1

Ingredient and nutrient composition are reported on an as-fed basis. Provided the following per kilogram of diet: Cu (CuSO4 × 5H2O), 10 mg; Mn (MnSO4 × H2O), 80 mg; Zn (ZnSO4 × 7H2O), 40 mg; Fe (FeSO4 × 7H2O), 80 mg; I (KI), 0.35 mg; Se (Na2SeO3), 0.15 mg. 3 For the diet from d 1 to 21, provided the following per kilogram of diet: vitamin A (all-trans retinol acetate), 12,000 IU; cholecalciferol, 2,500 IU; vitamin E (all-rac-α-tocopherol acetate), 20 IU; vitamin K (menadione Na bisulfate), 2.0 mg; thiamine (thiamine mononitrate), 2.0 mg; riboflavin, 6.0 mg; vitamin B6, 4.0 mg; vitamin B12, 0.0015 mg; pantothenate, 20 mg; niacin, 40 mg; folic acid, 0.8 mg; biotin, 0.10 mg. For the diet from d 22 to 42, provided the following per kilogram of diet: vitamin A (all-trans retinol acetate), 10,000 IU; cholecalciferol, 2,000 IU; vitamin E (all-rac-α-tocopherol acetate), 20 IU; vitamin K (menadione Na bisulfate), 2.0 mg; thiamine (thiamine mononitrate), 2.0 mg; riboflavin, 5.0 mg; vitamin B6, 3.5 mg; vitamin B12, 0.012 mg; pantothenate,15 mg; niacin, 30 mg; folic acid, 0.8 mg; biotin, 0.10 mg. 4 CP and Ca contents were determined by the method of AOAC (1990). 5 Xanthophyll in all treatment feeds was determined by HPLC analysis. 2

and water were freely available to all birds. The duration of the entire experimental period was 42 d. The birds were weighed at the beginning of the experiment. Body weight gain, feed intake, and FCR (ratio of feed to gain) were measured at 21 and 42 d on a pen basis. Visual observation of the color of shank skin was done with a color-graduated visual aid color fan (Roche color fan) at 21 and 42 d for all chickens, with minimum and maximum values ranging from 1 to 15 [23].

in initial BW (43.26 ± 0.35 g) across treatment groups. The 4 treatments consisted of a control treatment (basal diet; Table 1) and 0.1, 0.5, or 2.5% of LSC mixed into the basal diet every 3 d (the viable cell counts of L. salivarius were 0, 3 × 106, 1.5 × 107, and 7.5 × 107 cfu/g of feed, respectively). The basal diet (Table 1), broiler management, growth performance, and color evaluation for birds were the same as in experiment 1.

Experiment 2

At the end of experiment 2, two birds (8 from each treatment) were randomly selected from each pen. Birds were individually weighed and killed by cervical dislocation after a 12-h feed deprivation period. The left side thigh (biceps femoris) and breast (pectoralis major) muscles

A total of 208 one-day-old male Arbor Acres broilers [21] were allocated to 4 treatments, with 4 replicates of 13 birds per replicate pen for each treatment. There were no significant differences

Collection of Meat and Skin Samples

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Ingredient   Ground yellow corn   Soybean meal (44%)   Corn oil   Dicalcium phosphate (CaHPO4)   Ground limestone   Iodized salt   dl-Met   Choline chloride (50%)   Mineral2 and vitamin3 premix micronutrients2 Nutrient content   ME, kcal/kg   CP4   Lys   Met   Met + Cys   Ca4   Nonphytate P   Xanthophyll,5 mg/kg

Zhu et al.: LACTOBACILLUS CULTURES

Meat Color Evaluation and Myoglobin Analysis The color of the breast and thigh meat was measured by the CIE (Commission International d’Eclairage) system [Hunter L* (lightness), a* (redness), and b* (yellowness) values] with a handheld color-difference meter (SC-80C) [24]. An average of 3 readings from the surface of the medial muscle that were free of color defects, bruising, and hemorrhages were taken for color evaluation [4]. Myoglobin content of the breast and thigh muscle was determined by the method of Krzywicki [25]. A 5-g meat sample was homogenized in 15 mL of PBS and then centrifuged at 1,000 × g for 30 min (10 to 15°C), and the solution was passed through a filter paper. Absorbance of the solution was determined at 572, 565, 545, and 525 nm with a UN-VIS 8500 spectrophotometer [26]: Myoglobin (µg/g of wet muscle) =

-0.166 A572 + 0.086 × A565 + 0.088 × A545 + 0.099 × A525 .

Carotenoid Analysis Extraction and analysis of carotenoid deposition in poultry tissues (from the serum, shank skin, and breast meat) were as follows. All procedures were completed under amber light or in amber tubes. The extraction of carotenoids in serum was based on the method described by Barua et al. [27]. An aliquot of the serum (0.5 mL) was pre-

cipitated with 1 mL of absolute ethyl alcohol containing 1% ascorbic acid (wt/vol) and stirred vigorously on a vortex shaker; n-hexane (2 mL) was added to the homogenate for extraction. The mixture was stirred again, and the precipitate was centrifuged at 2,000 × g for 5 min. The hexane layer was removed and the extraction was repeated twice. The pooled hexane layers from both extractions were evaporated to dryness under a stream of nitrogen. The residue was then dissolved in the mobile phase of the HPLC. Extraction of carotenoids in the shank skin was done with a modification of the technique of Heiman and Tighe [28] as follows. The skin of the shank was removed and cleaned of all underlying fat. A 5-mm-diameter punch was taken with a cork borer from each piece of skin. Ten punches from each bird were pooled and weighed, milled, and extracted in 10 mL of acetone for 1 h. The residue was dissolved in 60 mL of ethanol (mixed with 1.0 mL of ascorbic acid) and 2 mL of 40% aqueous potassium hydroxide. The mixture was kept in a water bath at 70°C for 15 min. The mixture was extracted with 6.0 mL of hexane for 30 min; 5 mL of the top organic phase was removed and dried under a stream of nitrogen. The residue was then dissolved in the mobile phase of the HPLC. Extraction of carotenoids in the breast muscle and feed followed the method of Tyczkowki and Hamilton [29]. Samples with wet weights of approximately 0.2 g were homogenized in PBS and deproteinized with an equal volume of ethanol. Samples were homogenized in PBS at a ratio of 2 parts PBS to 1 part tissue (vol/wt). Ethanol was added at twice the sample volume and shaken vigorously for 5 min. Hexane was added at 1× the sample volume, shaken for 5 min, and centrifuged at 5,000 × g for 15 min. The top organic phase was removed in a tube, and the residue was extracted again. The pooled organic phase was dried under a stream of nitrogen. The residue was then dissolved in the mobile phase of the HPLC. The HPLC analysis of carotenoids is described elsewhere [30]. Statistics and Analysis of Data The data were analyzed by ANOVA using the GLM procedure of SAS software [31]. When significant differences were found, the LSD test

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without skin and adipose tissues were collected. One-half of the raw breast and thigh meat samples were used to measure pH and color. The rest of the raw samples were stored in sealed plastic bags at −20°C for moisture and lipid, carotenoid, and myoglobin concentration assays. A blood sample from each individual broiler was collected at the end of d 21 and 42. Blood was collected from the brachial vein of overnight-fasted broilers by using sterilized syringes and needles. After serum was allowed to stand for 1 h at room temperature, it was separated by centrifugation at 3,000 × g for 10 min. Serum samples were stored at −20°C until analysis.

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574 was conducted. Levels of statistical significance and extreme significance were based on values of P < 0.05 and P < 0.01, respectively.

RESULTS AND DISCUSSION Growth Performance

Color of Shank Skin and Meat The results of experiment 1 showed that dietary supplementation with LC affected the RCF score of the shank skin of broilers (Table

Carotenoid Concentrations in Serum and Tissues The data in Table 5 clearly show that xanthophyll concentrations were increased in the shanks of birds supplemented with LSC. Xanthophyll contents in the shank skin of birds with 0.5 and 2.5% of LSC increased to 2.12 and 1.85 μg/10π mm2 from 0.95 μg/10π mm2 of chickens

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In experiment 1, the growth performance of broiler chickens from d 1 to 21 was affected by the diets supplemented with LC (Table 2). The ADG and feed intake of the birds fed diets supplemented with L. plantarum culture YJG were significantly superior (P < 0.05) to those of the control group. The FCR of the LA group was inferior to that of the control group (P < 0.05). No significant differences were observed in the growth performance of birds for the 21- to 42-d and 1- to 42-d periods across the treatments. In experiment 2, there were no differences in the growth performance of birds fed diets not supplemented or supplemented with LSC (Table 3). It has been reported that feeding Lactobacillus improves BW gain [13–16, 28] and feed conversion [15, 17, 18, 32, 33]. The dietary supplementation with L. plantarum significantly improved ADG in the starter period, which agreed with the results of Yeo and Kim [34], who reported that the average daily BW gain of chickens fed probiotics was significantly increased during the first 3 wk of growth, but not during the fourth to sixth weeks of growth, whereas Mohan et al. [35] observed that the beneficial effect of probiotics on chickens occurred only after the fourth week. However, dietary supplementation with LSC did not improve growth performance in experiment 1 or experiment 2. This was consistent with the results of Huang et al. [36], who did not find differences in BW gain or feed conversion between probiotic-treated and untreated control birds. These varying results may be due to differences in species composition, origin, and viability of the probiotic (bacterial strains); application method; bird age; overall farm hygiene; and environmental factors [12, 37, 38].

2). Compared with the control treatment, RCF scores of the shank skin were significantly increased by diets supplemented with L. salivarius MA at d 21 and 42 (P < 0.01), L. acidophilus LA culture at d 21, or L. plantarum SRP culture at d 42 (P < 0.01). An additional experiment was carried out to evaluate the effects of L. salivarius MA in experiment 2. The results (Table 3) showed that RCF scores of the shank skin of birds fed LSC were significantly increased at d 21 and 42 (P < 0.001). The RCF score of the shank skin of birds fed 2.5% LSC was increased by 1.4 points above that of the control group. However, our laboratory previously reported that dietary supplementation of LC resulted in a 3- to 4-point increase in the RCF score for the shank skin of chickens [19, 20]. These results showed that dietary supplementation with LC significantly increased the color of chicken shank skin. Myoglobin content of the breast and thigh muscles was not significantly affected by treatments (Table 4). The yellow (b*) thigh meat color was significantly increased after LSC supplementation in the diet (P < 0.05). There were no significant differences in redness (a*) or lightness (L*) of the breast and thigh muscles, although redness (a*) of the breast muscle of birds fed 2.5% LSC was increased to 8.10 from 7.22 (control group). To date, there have been few reports of dietary probiotics affecting the color of the meat and shank skin of chickens. Karaoğlu et al. [8, 9] reported that the use of a probiotic (containing Saccharomyces cerevisiae) in broiler diets significantly diminished the L* values and increased the b* values of broiler carcass skin. Akiba et al. [39] reported that higher a* (red) and b* (yellow) values of meat were found in the breast by supplementing Phaffia yeast with a high-astaxanthin concentrate.

33.86ab 55.52ab 1.64b 6.70ab 2,126.4 61.40 114.3 1.87 7.80A 47.63 84.92 1.78

1,944.6 53.89 106.35 1.90 7.35B

43.94 78.94 1.81

L. plantrua SRP

30.98b 51.52b 1.66b 6.10b

Control

A,B

45.71 80.31 1.76

1,945.5 57.04 103.45 1.84 7.22B

34.36a 57.18a 1.66b 6.19b

L. plantrua YJG

47.96 85.74 1.80

2,122.9 64.95 128.05 1.85 7.87A

30.97b 52.81ab 1.70ab 6.88a

L. salivarius MA

47.5 82.11 1.73

2,066 65.08 110.42 1.70 7.50AB

29.91b 53.80ab 1.80a 6.95a

42.92 83.59 1.95

2,004 53.59 111.8 2.07 7.33B

32.24ab 55.36ab 1.71ab 6.78ab

0.419 0.507 0.015 0.093 31.8 1.50 1.52 0.04 0.068 0.795 0.721 0.032

1,820 52.91 110.2 1.77 6.49B 42.98 82.32 1.91

SEM 33.05ab 54.42ab 1.65b 6.25ab

L. acidophilus L. acidophilus L. acidophilus LA GA SJ

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Means within a row with different superscripts differ (P < 0.05). Means within a row with different superscripts differ (P < 0.01).

a,b

Day 1 to 21   ADG, g/d   ADFI, g/d   FCR, kg of feed/kg of gain   Roche color fan score of shank at d 21 Day 21 to 42   Final BW, g/bird   ADG, g/d   ADFI, g/d   FCR, kg of feed/kg of gain   Roche color fan score of shank at d 42 Day 1 to 42   ADG, g/d   ADFI, g/d   FCR, kg of feed/kg of gain

Item

Table 2. Effects of dietary supplementation of Lactobacillus culture treatments on the growth performance and Roche color fan scores of broiler chickens

0.212 0.120 0.378

0.085 0.123 0.149 0.493 0.01

0.016 0.043 0.037 0.01

P-value

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Table 3. Effect of level of dietary Lactobacillus salivarius culture on BW gain, FCR, and Roche color fan score of broiler chickens    Level of dietary L. salivarius culture Item

0

A–C

0.5%

28.77 1.45 6.90A

26.02 1.38 6.82A

27.71 1.47 5.56B 2,028.5 66.82 2.00 7.02C

2,148.7 71.47 1.87 7.48BC

2,019.0 68.11 1.77 7.95AB

50.13 1.74

47.06 1.68

47.26 1.82

2.5%

SEM

P-value

26.69 1.475 7.20A

0.518 0.016 0.178

0.270 0.213 0.001

1,972.4 65.16 1.86 8.42A

33.48 1.237 0.034 0.144

0.304 0.344 0.120 0.001

0.795 0.023

0.305 0.161

45.92 1.73

Means within a row with different superscripts differ (P < 0.01).

without feed LSC (P < 0.001). Compared with the birds without dietary LSC, the xanthophyll (4.82 vs. 2.63 μg/mL) and β-carotene (1.37 vs. 0.81 μg/mL) concentrations in the serum of birds fed diets with 0.5% of LSC at d 42 were increased, but not significantly. Skin color is dependent on the absorption and deposition of carotenoid pigments in the epidermis [4, 40]. Poultry cannot synthesize these compounds and must obtain carotenoids from their diets [4]. The absorption and accumulation of carotenoids are affected by diets, diseases, and parasitic infestations [6, 7]. The levels of plasma carotenoids were markedly reduced after chickens were infected with Eimeria acervulina and Eimeria tenella [6, 41]. Waldenstedt

et al. [42] found that inoculation with C. jejuni significantly decreased tissue astaxanthin concentrations in the kidney, intestine, and breast muscle compared with noninoculated birds but that it had no significant effect on plasma carotenoid levels. Therefore, the alteration in intestinal microbiota may result from improving the absorption and accumulation of xanthophylls by dietary supplementation of LSC. The present study showed that there was no difference between myoglobin content of the thigh and breast muscle of birds fed diets supplemented with LSC and that of the control group, although myoglobin content in meat is considered a major factor contributing to meat color [3, 4]. Many studies have shown that meat

Table 4. Effect of level of dietary Lactobacillus salivarius cultures on broiler meat myoglobin and color of the breast and thigh of broiler chickens Level of dietary L. salivarius culture Item Breast muscle   Myoglobin content, μg/g   L* (lightness)   a* (redness)   b* (yellowness) Thigh muscle   Myoglobin content, μg/g   L* (lightness)   a* (redness)   b* (yellowness) a,b

0

0.1%

0.5%

2.5%

SEM

P-value

1.42 61.85 7.22 6.39

1.50 63.27 7.98 6.21

1.05 59.57 7.86 6.62

1.16 64.11 8.10 6.37

0.117 1.000 0.385 0.179

0.088 0.446 0.866 0.622

2.95 68.84 6.25 4.85b

3.22 61.28 6.05 6.44a

3.21 69.26 6.79 6.23a

3.20 66.57 7.22 6.39a

0.156 3.321 0.449 0.234

0.922 0.371 0.533 0.041

Means within a row with different superscripts differ (P < 0.05).

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Day 1 to 21   ADG, g/d   FCR, kg of feed/kg of gain   Roche color fan score of shank at d 21 Day 22 to 42   Final BW, g/bird   ADG, g/d   FCR, kg of feed/kg of gain   Roche color fan score of shank at d 42 Day 1 to 42   ADG, g/d   FCR, kg of feed/kg of gain

0.1%

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Table 5. Effect of level of dietary Lactobacillus salivarius culture on β-carotene and xanthophyll in the serum and tissues of broiler chickens Level of dietary L. salivarius culture Item Xanthophyll in serum at 21 d, μg/mL β-Carotene in serum at 21 d, μg/mL Xanthophyll in serum at 42 d, μg/mL β-Carotene in serum at 42 d, μg/mL Xanthophyll in breast muscle, μg/g Xanthophyll in shank skin, μg/10π mm2

0.1%

0.5%

2.5%

SEM

P-value

2.97 0.59 2.63 0.81 0.44 0.95B

3.21 0.52 3.64 1.13 0.46 1.36AB

3.11 0.68 4.82 1.37 0.50 2.12A

3.94 0.61 4.65 1.27 0.62 1.84A

0.279 0.268 0.361 0.097 0.030 0.121

0.532 0.223 0.085 0.07 0.132 0.001

Means within a row with different superscript differ (P < 0.01).

color and carotenoid concentrations in muscle are modified by composition of the bird diets [43, 44]. Waldenstedt et al. [42] found that astaxanthin concentration in the breast increased from 0 to 300.54 mg/kg with the level of astaxanthin in diet (from 0 to 179 mg/kg). Although xanthophyll concentration in the breast of birds fed 2.5% LSC increased to 0.62 μg/g (0.44 μg/g without LSC), there was no significantly difference among treatments (P > 0.05) in carotenoid content in the breast muscle. In conclusion, dietary supplementation with LC increased the RCF score of the shank skin of broilers. The reason may be the elevation of xanthophyll concentration in the serum and shank skin of broilers fed a diet with LC.

CONCLUSIONS AND APPLICATIONS

1. Supplementation of broiler feed with LSC increased the RCF score of chicken shank skin. 2. The yellowness (b*) values of thigh meat were significantly increased for broilers fed LSC. 3. Broiler growth performance was improved by dietary supplement with L. acidophilus LA culture from 1 to 21 d, but not thereafter.

REFERENCES AND NOTES 1. Liang, Y. D., J. Y. Yin, and B. F. Huang. 2004. Effect of supplemental canthaxanthin and apo-ester in diets on performance of laying hens and yolk color . China Poult. 8:161–163. 2. Castaneda, M. P., E. M. Hirschler, and A. R. Sams. 2005. Skin pigmentation evaluation in broilers fed natural and synthetic pigments. Poult. Sci. 84:143–147.

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Acknowledgments

The authors thank the National Key Basic Research Program of China (“973 Program,” Project No. 2004CB117500, Ministry of Science and Technology of China) for the support given.

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