1 Çukurova University, Agricultural Faculty Department of Animal Science 01330 Adana-Turkey 2 Yüzüncüy•l University, Agricultural Faculty Department of Animal Science 65330 Van-Turkey
EFFECTS OF DIETARY LYCOPENE ON LAYING PERFORMANCE AND EGG QUALITY OF BROWN LAYERS
N. DOGAN1, L. CELIK1, A. TEKELI2, Z. BOZKURT1 and H. R. KUTLU1 Summary
The present study was conducted to evaluate whether dietary lycopene would affect laying performance and egg quality of Brown layers. Twenty eight weeks old layers were divided into 4 groups of similar mean weight, comprising 18 birds each. The birds were fed standard layer diets containing 0, 100, 200 and 400 ppm lycopene (Lyc-O-Mato® containing 0.8% Lycopene) for 8 weeks period. The birds were housed in individual cages in a complete randomized design. A 16:8 hours light:dark photoperiod was employed. Feed and water were given ad libitum. Laying performance was assessed by recording feed intake, egg weight, egg mass, feed conversion efficiency and body weight. The results showed that lycopene supplementation did not have significant (P>0.05) effects on feed intake, egg weight, egg mass, feed conversion efficiency, body weight, plasma glucose and tryglyceride concentrations. However, dietary supplemental lycopene increased yolk color score, shell weight, shell thickness and plasma cholesterol level (P<0.05) in a dose related manner . The results suggest that providing dietary lycopene, especially 100 ppm, could have a potential to increase egg quality in terms of yolk pigmentation and shell quality.
I. INTRODUCTION
Lycopene is a carotenoid that refers to an acyclic carotene with 11 conjugated doub le bonds arranged linearly, usually in the trans-configuration (Bramley, 2000). Lycopene has attracted attention more recently. It has claimed that lycopene playing a crucial role with its carcinogenic (•ahin et al., 2005), atherosclerotic (Tang et al., 2006), anti-hypercholesterolmic (Fuhrman et al., 1997), and anti-oxidant (Karadas et al., 2006) effects in several species of growing monogastric animals. Lycopene has also been reported to enhance immune function (Olson and Koutsos, 2007) in laying hens . With regard to laying performance and egg quality, lycopen as a feed additive or some feedstuff containing lycopen were also tried to evaluate. Dried tomota products (rich in lycopen, as meal or pulp) have been reported to improve egg quality (Yannakopoulos et al., 1992; Dotas et al., 1999; Jafari et al., 2006). However, the positive effects were not addressed in terms of mode of action. Therefore it is not known whether the positive effects could be attributed to lycopen or not. Nevertless, lycopen as a fitobiotic could improve laying performance and also interior and exterior egg quality.
Yolk colour has been regarded as an important egg quality charasteristic and has had an even more important role in egg marketing. The yolk coloring agents supplemented with lycopene could give to yolk a characteristic red pigmentation. Apart from the yolk color, the other major concern of egg producers is low eggshell strength. In fact, many ad ditives have been tried with varying degrees of success to improve egg quality in terms of interior and exterior characteristics for last two decades. Some tomato products have been reported to have positive effects on egg quality. Lycopen as a bioactive compound of tomota by product, with its effects on pigmentation and mineral metabolism was thought to be one of those agents for improving egg quality. Therefore, the present study was undertaken to examine the potential use of lycopene and its effects on performance, egg quality and some plasma parameters of laying hens.
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II. METHODS
Prior to the trial, seventy-two, 26-weeks-old layers were fed ad libitum with a standard layer diet for two weeks period, during which daily egg production and egg weight were recorded. At the beginning of the trial period, when the birds were 28 weeks old, they were divided into 4 experimental groups of similar mean body weight and egg production level, comprising 18 birds each. The birds were fed a diet supplemented with 0, 100, 200, or 400 ppm lycopene (obtained from Lyc-O-Mato®; lycopene rich tomato products in powder form, containing min. 0.8% Lycopene, 12.5, 25 and 50 g/kg feed, respectively) for a period of 8 weeks. Lyc-O-Mato® obtained from LycoRed SARL, Schaffhausen, Switzerland. The standard layer (The first phase-cage) diet obtained from a commercial feed company was used as a basal feed. The birds were housed in individual layer cages of three-tier battery blocks in a complete randomized design at a conventional ambient temperature (20-22°C) with a relative humidity of 60-70%. Light was provided 16 hours (from 05.00 to 21.00) each day. Performance was determined daily by measuring feed intake, egg mass, feed conversion ratio (egg mass:feed intake) and egg production (in house, number and weight). Egg quality was estimated by measuring egg-shape index (width/length), shell weight, shell thickness, egg weight, yolk weight, albumen weight, albumen height, yolk index (weigh/height) and yolk colour score (Roche, Yolk Colour Fan) of each egg obtained on the third day of every week. Shell samples from top, middle and bottom of the egg were measured for thickness using a micrometer and the mean was calculated prior to statistical analysis. Five birds from each group were randomly chosen and samples of blood were taken via vena brachialis biweekly throughout the experiment. After centrifugation, the plasma was collected and stored at -20°C pending analysis for glucose, cholesterol and triglycerides.
The data obtained in the experiment were analysed using the General Linear Models (GLM) and orthogonal polynomial of SAS (1985). Linear, quadratic and cubic effects were determined by orthogonal polynomial contrasts.
III. RESULTS and DISCUSSION
The performance, egg quality and plasma parameters of laying hens receiving different level lycopene are summarized in Table 1.
The results showed that lycopene supplementation did not have significant (P>0.05) effects on feed intake, egg weight, egg mass, feed conversion efficiency, body weight, plasma glucose and tryglyceride concentrations. However, dietary supplemental lycopene increased yolk color score, shell weight, shell thickness and plasma cholesterol level (P<0.05) in a dose related manner. The result obtained in the present experiment with respect to yolk colour score is supported to the findings of Dotas et al. (1999) and Persia et al. (2003). In fact, they did not use dietary lycopen directly; they used dried tomato paste as an alternative feedstuff for layers. Our findings with respect to egg shell weight and thickness are, however, not in agreement with the findings of Yannakopoulos et al. (1992) and Jafari et al. (2006). They reported no effect of dried tomato paste or tomato meal on egg quality. They did not report lycopen content of the tomota products. Therefore, ineffectiveness or effectiveness of the tomato products on eggs quality could not be associated with lycopene. However, our tomota products containing lycopene has positive effects on egg quality in terms of yolk colour and also shell thicknes and shell weight with an elevation of plasma cholesterol level. In fact, no explanation could be provided for the elevation of plasma cholesterol. The present literature revealed that dietary supplemental carotenoids may act as moderate hypocholesterolemic agents, secondary to their inhibitory effect of macrophage 3-hydroxy-3-methyl glutaryl
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coenzyme A (HMGCoA) reductase, the rate limiting enzyme in cholesterol sytnhesis (i.e. Fuhrman et al., 1997) . However, in our study, lycopene seems to increase cholesterol secretion or synthesis. Therefore, the results obtained with respect to plasma cholesterol concentration needs to evaluate in further studies to provide detailed information about possible effect(s) of lycopene on cholesterol metabolism.
Table 1. Effects of Dietary Lycopene on Performance, Egg Quality and Some Plasma Parameters of Laying Hens.
Dietary Lycopene Level (mg/kg) Main effects ¥
Parameters
0 100 200 400
SED P
L Q C
Initial bod y weight (g) 1593.39 1593.06 1587.06 1597.83 21.15 - - - -
Final body weight (g) 1641.72 1624.22 1670.17 1655.33 21.57 - - - -
Total feed intake (FI; g/bird/42 days) 751.83 787.97 718.24 771.03 16.25 - - - - Feed conversion ratio (EM/FI) 0.40 0.39 0.38 0.37 0.01 - - - - Egg mass (EM; g/bird/42 days) 2305.94 2410.66 2192.08 2267.56 48.69 - - - -
Mean egg weight (g/bird) 56.92 58.42 57.20 57.90 0.43 - - - -
Egg weight (g/day) 57.54 58.66 57.88 58.63 0.43 - - - -
Egg width (mm) 42.56 43.01 42.37 42.68 0.15 - - - -
Egg length (mm) 56.15 56.08 56.33 56.31 0.19 - - - -
Shell weight (g/egg) 6.32 6.51 6.43 6.64 0.05 - * - -
Yolk weight (g/egg) 14.34 14.43 14.41 14.27 0.08 - - - -
Albumen weight (g/egg) 36.89 37.69 36.65 37.70 0.35 - - - -
Egg Yolk score 11.00 12.10 11.88 11.89 0.09 ** ** ** *
Egg Yolk index 48.10 47.95 47.77 47.45 0.24 - - - -
Albumen index 6.38 6.39 6.16 6.07 0.16 - - - -
Mean shell thickness (µm) 332.71 347.49 341.15 337.54 2.45 - - * -
Plasma Glucose (ml/dl) 207.02 203.28 205.72 198.66 1.92 - - - -
Plasma Cholesterol (ml/dl) 84.46 87.89 85.68 104.13 3.37 - * - -
Plasma Tryglyceride (ml/dl) 578.19 517.15 540.41 665.18 26.33 - - - -
*: P<0.05 **: P<0.01 - : Not significant (P>0.05) ¥: L:linear; Q: quadratic; C: cubic effects SED: standart error of difference between means.
It could be concluded that providing dietary lycopene, especially 100 ppm could have a potential to increase egg quality in terms of yolk pigmentation and shell thickness.
ACKNOWLEDGEMENTS
The authors are grateful to Çukurova University Research Fund (ZF-2006-YL87) for financial support.
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