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Effects of supplemental L-carnitine in drinking water on performance and egg quality of laying hens exposed to a high ambient temperature

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Department of Animal Science, C¸ ukurova University, Adana, Turkey

Effects of supplemental

L

-carnitine in drinking water on

performance and egg quality of laying hens exposed to a high

ambient temperature

By L. B. C¸ elik, A. Tekeli and O. O¨ ztu¨ rkcan

Summary

The present study was conducted to investigate effects of l-carnitine supplied with drinking water on performance and egg quality of laying hens under high environmental temperature. In the study, 47-week-old laying hens (Brown hisex) were divided into two groups (control and treatment) and fed with a standard layer diet. Treatment group was received 50 p.p.m l-carnitine with drinking water for an 8-week period. Throughout the study, 8 h hot (35–37 °C) and 16 h thermoneutral (20–22 °C) environmental temperature regime was employed daily. The results showed that l-carnitine supplementation affected some egg quality characteristics of layers under high environmental temperature. Relative albumen weight and height were increased (p < 0.05) by supplemental l-carnitine. Live weight gain, feed intake, egg mass, egg weight, yolk weight, shell weight, yolk index, egg-shape index, yolk colour score and shell thickness were not affected (p < 0.05) by l-carnitine. It is concluded that l-carnitine supplementation in laying hens could have potential to improve albumen quality under high environmental temperature.

Introduction

Birds are homoeothermic, meaning that they maintain their body temperature at about the same level over a wide range of environment. In many countries of the world, particularly in the hot and humid tropics, poultry are often maintained at environmental temperatures above the zone of thermoneutrality. It is well-documented that high environmental temperatures depress broiler or layer productivity and also product quality (i.e. Bollengier-Lee et al., 1998; Kutlu, 2001). Very often the reduction in performance is attributed to the birds rapidly reducing their feed intake at higher temperatures in order to reduce the heat increment of feeding. However, it has also been speculated that the depression in performance is not only a reflection of inadequate energy and nutrient but also a result of metabolic changes induced by stress itself (Kutlu and Forbes, 1993a–c).

Attempts to lessen the severity of high environmental temperatures in egg production systems have been a major concern. As it is expensive to cool animal buildings, many dietary methods have been tried with varying degrees of success over the past 30 years in order to identify the most limiting nutrients(s) or re-establish physiological equilibrium to correct protein synthesis and the generation of metabolic energy (ME) in the body during heat stress.

It has been reported that carnitine plays a significant role in energy metabolism as a carrier for the transport of the activated long chain fatty acids across the inner mitochondrial membrane, besides being a binder of acetyl groups, leading to increase the Ó2004 Blackwell Verlag, Berlin

ISSN 0931–2439

Accepted: 30. 10. 2003

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pool free coenzyme-A, which stimulates the generation of ME (Bremer, 1983; Borum, 1991). It is, therefore, speculated that carnitine supplementation of diets could be beneficial for energy metabolism; thereby facilitating fatty acid oxidation and balancing energy deficit by using the long chain fatty acids under stressful conditions (Rebouche, 1992).

Dietary supplemental carnitine studies on poultry have mostly focused on broilers; since l-carnitine was demonstrated to have beneficial effects on broilers under stressful conditions, it has been accepted as a potential protecting agent for broilers in the case of stress induced by high environmental temperatures (i.e. C¸ elik and O¨ ztu¨ rkcan, 2003). However, little research has been carried out to examine possible role of dietary supplemental carnitine in laying hens. Research carried out under thermoneutral condition exhibited inconsistent results in terms of positive effects of dietary l-carnitine on egg production and quality. Leibetseder (1995) reported that the supplementation of a standard layersÕ ration with either 500 mg l-carnitine or nicotinic acid or a combination of the two substances, had no effects on egg production, feed intake, body weight or concentrations of serum or yolk cholesterol during the early laying period. However, l-carnitine content of yolks was significantly increased in the supplemented groups. Rabie et al. (1997a) observed that l-carnitine (50 mg/kg diet) has positive effects on interior egg quality during the early stages of egg production. In the late laying period, l-carnitine had beneficial effect on albumen quality and could modify the components of the edible part of the egg (Rabie et al., 1997b).

However, in the present literature no research has been found on the evaluation of l-carnitine in laying hens under high environmental temperature. Therefore, the present study was undertaken to evaluate the effects of l-carnitine supplied by drinking water on performance and egg quality of laying hens under high environmental temperature.

Materials and methods

Prior to the trial, 20 46-week-old layers were fed ad libitum with a standard layer diet for a week period, during which daily egg production and egg weight were recorded. At the beginning of the trial period, when the birds were 47 weeks old, they were divided into two experimental groups (control and treatment) of similar mean body weight and egg production level, comprising 10 birds each. The standard layer (second phase-cage) diet (Table 1) obtained from a commercial feed company was used as a basal feed. The treatment group received drinking water supplemented with l-carnitine (Carniking, product of Lohmann, Cuxhaven, Germany) at the level of 50 mg/l water. l-Carnitine supplementation to drinking water of the treatment group was performed everyday freshly. Throughout the experiment, which lasted 8 weeks, feed and water were given ad libitum. The birds were housed in individual layer cages of two-tier wire blocks in a complete randomized design at a conventional ambient temperature (20–22 °C) with a relative humidity of 60–70%, except during period of heating when the environmental temperature fluctuated from 35 to 37 °C with a relative humidity of 40–50% for 8 h per day (09:00–17:00 hours). Light was provided 16 h (from 05:00 to 21:00 hours) each day. Performance was determined daily by measuring feed intake, egg mass, feed conversion ratio (egg mass : feed intake), egg production (in house, number and weight) and number of cracked eggs. 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 (weight/height) and yolk colour score (Roche, Basel, Switzerland; Yolk Colour Fan) of each egg obtained on the third and sixth days 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.

The data with respect to laying performance and egg quality (pooled) were subjected to t-test using spss (1999).

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Results

The performance and egg quality of laying hens receiving l-carnitine with drinking water are summarized in Table 2.

The results obtained in the experiment showed that supplemental l-carnitine had significant effects on relative albumen weight (p < 0.01) and albumen height (p < 0.05). However, all other parameters of performance and egg quality were not influenced (p > 0.05) by supplemental l-carnitine.

Discussion

The results obtained in the present experiment suggest that l-carnitine given with drinking water could have a potential to improve egg quality by increasing albumen weight and height. In fact, reports on the effects of dietary l-carnitine on egg quality of laying hens are limited. No comparable data could be found in the literature on the effects of supplemental dietary l-carnitine on egg quality of hens under heat stress. Studies with layers under thermoneutral condition have shown some favourable responses to dietary l-carnitine (Leibetseder, 1995; Rabie et al., 1997a,b). Rabie et al. (1997a,b) observed significant improvement on albumen quality of laying hens during early and late laying period in response to supplemental dietary l-carnitine. The positive effects of supplemental

Table 1. Composition and nutrient contents of the basal diet Ingredient (g/kg) Yellow corn 200.00 Barley 140.40 Soyabean meal (420 g/kg CP) 47.10 Sunflower meal (300 g/kg CP) 78.59 Wheat bran 150.00 Wheal middlings 170.00

Meat and bone meal 70.00

Poultry by-product meal 40.49

Full fat-soya 36.69 Salt 1.99 Limestone 60.54 Vitamin premixa 2.00 Mineral premixb 1.00 Methionine 0.78 Analyses (g/kg) Dry matter 899.8 Crude protein 162.0 Ether extract 58.6 Crude fibre 60.3 Crude ash 122.0 Lysinec 6.7 Methionine + cystinec 6.2 Calciumc 35.0 Available Pc 4.0 Sodiumc 2.0

Metabolic energy (ME, MJ/kg)c 11.1

aEach 2 kg of vitamin premix contains 6 000 000 IU vitamin A, 800 000 IU vitamin D 3,

14 000 mg vitamin E, 1600 mg vitamin K3, 1250 mg vitamin B1, 2800 mg vitamin B2, 8000 mg

niacin, 4000 mg Ca-D-pantothenate, 2000 mg vitamin B6, 6 mg vitamin B12, 400 mg folic acid,

18 mg d-biotin, 20 000 mg vitamin C, 50 000 mg choline chloride

b

Each kg of mineral premix contains 80 000 mg manganese, 60 000 mg iron, 60 000 mg zinc, 5000 mg copper, 200 mg cobalt, 1000 mg iodine, 150 mg selenium

c

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l-carnitine on the albumen quality in the present study support the findings reported by Rabieet al. (1997a,b). The results of the present study showed that supplemental l-carnitine increases albumen quality and induced a favourable alteration in the components of the edible part of the egg in laying hens at high environmental temperature. Although egg weight was not influenced by l-carnitine, the percentage of albumen weight increased and that of egg yolk decreased in l-carnitine supplemented group compared with the control group. The differences are most probably because of the higher metabolic rate of albumen in the magnum and/or higher activity of shell gland of the hens receiving supplemental l-carnitine compared with control. The quality of the albumen is largely dependent on the amount of ovomucin, particularly b-ovomucin, secreted by the magnum. It is reported that b-ovomucin is mainly responsible for the gelatinous properties of the thick albumen gel (Anonymous, 2000). It could, therefore, be speculated that l-carnitine may play a role in the synthesis or secretion of b-ovomucin by promoting ME generation in the magnum.

Furthermore, as the albumen is known to be a carrier for antioxidant, antimicrobials, spices (Froning, 1998), the increase in albumen weight could also be a benefit for the nutritional point of view, and also for improving storage time.

It could be concluded that supplemental l-carnitine (50 p.p.m.) provided in drinking water could have a potential to improve egg quality through increasing relative albumen weight and albumen height in laying hens under high environmental condition.

Acknowledgements

The authors are grateful to C¸ ukurova University, Agricultural Faculty, Revolving Fund for animal and feed materials and also Lohmann Animal Health, Cuxhaven, Germany for gifts of Carniking. Table 2. Effects of l-carnitine given in drinking water on performance and egg quality of laying

hens

Parameters

Supplemental l-carnitine

t-Value

(0 mg/l) (50 mg/l)

Initial body weight (g) 2018.8 ± 219.8 2016.8 ± 217 0.276

Final body weight (g) 1921.64 ± 58 1845.82 ± 75 0.798

Total feed intake (FI; g/bird/56 days) 6462.89 ± 248 5949.45 ± 225 1.535

Egg mass (EM; g/bird/56 days) 2898.91 ± 275 2994.77 ± 178 0.293

Feed conversion ratio (EM/FI) 0.512 ± 0.04 0.503 ± 0.03 0.208

Hen house egg production (%) 92.64 ± 8.77 95.46 ± 5.68 0.270

Egg weight (g/bird/day) 51.91 ± 4.94 53.55 ± 3.14 2.280

Number of cracked eggs (bird/56 days) 7.46 ± 2.44 9.82 ± 3.44 0.561

Cracked eggs (%) 18.75 ± 5.44 20.43 ± 6.89 0.192

Mean egg weight (g/bird) 68.28 ± 1.46 66.69 ± 1.60 0.735

Shell weight (g/egg) 8.47 ± 0.35 7.94 ± 0.14 1.413

Shell weight (%) 12.39 ± 0.40 11.95 ± 0.30 0.875

Yolk weight (g/egg) 18.16 ± 0.42 16.89 ± 0.41 2.134

Yolk weight (%) 26.61 ± 0.40 25.39 ± 0.60 0.213

Albumen weight (g/egg) 41.42 ± 0.97 42.16 ± 1.41 0.435

Albumen weight (%) 60.64 ± 0.40 63.12 ± 0.88 2.576**

Albumen height (mm) 5.43 ± 0.25 7.00 ± 0.52 2.737*

Egg width (cm) 4.49 ± 0.04 4.48 ± 0.05 0.156

Egg length (cm) 6.00 ± 0.05 5.92 ± 0.06 1.091

Yolk index 41.25 ± 0.51 42.43 ± 0.63 1.456

Egg shape index 74.96 ± 0.77 75.85 ± 1.23 0.609

Yolk colour score 9.21 ± 0.66 9.43 ± 0.49 0.275

Shell thickness (lm) 377.98 ± 20.4 364.35 ± 9.95 0.601

*p < 0.05, **p < 0.01

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References

Anonymous, 2000: Egg-grading Manual. U.S. Dept. Agri. Agricultural Marketing Service, Agricultural Handbook, Number 75.

Bollengier-Lee, S.; Mitchell, M. A.; Utomo, D. B.; Williams, P. E. V.; Whitehead, C. C., 1998: Br. Poult. Sci. 39, 106.

Borum, P. R., 1991: Boletin de la Associacio´ n Me´ dica de Puerto-Rico 83, 134. Bremer, J.; 1983: Physiol. Rev. 63, 1420.

C¸ elik, L.; O¨ ztu¨ rkcan, O., 2003: Arch. Anim. Nutr. 57, 27.

Froning, G. W., 1998: Recent advances in egg products research and development. Egg Processing Workshop, Riverside and Modesto, University of California , June 2–3, 1998.

Kutlu, H. R., 2001: Arch. Anim. Nutr. 54, 127.

Kutlu, H. R.; Forbes, J. M., 1993a: World Rev. Anim. Prod. 28, 15. Kutlu, H. R.; Forbes, J. M., 1993b: Livestock Prod. Sci. 36, 335. Kutlu, H. R.; Forbes, J. M., 1993c: Physiol. Behav. 53, 103. Leibetseder, J., 1995: Arch. Anim. Nutr. 48, 97.

NRC, 1994: Nutrient Requirements of Poultry, 9th Revised Edition. National Academy Press,

Washington, DC, USA.

Rabie, M. H.; Szilagyi, M.; Gippert, T., 1997a: A´ llattenye´ szte´s e´s Takarma´nyoza´s 46, 457. Rabie, M. H.; Szilagyi, M.; Gippert, T., 1997b: Br. J. Nutr. 78, 615.

Rebouche, C. J., 1992: Faseb J. 6, 3379.

SPSS, 1999: Computer Program, MS for Windows, Version 10.01. SPSS, USA.

Author’s address: Dr Ladine Baykal C¸ elik, Agricultural Faculty, Department of Animal Science, C¸ ukurova University, 01330 Adana, Turkey. Tel: +90 322 338 70 27; Fax: +90 322 338 65 76; E-mail: ladine@cu.edu.tr

Şekil

Table 1. Composition and nutrient contents of the basal diet Ingredient (g/kg) Yellow corn 200.00 Barley 140.40 Soyabean meal (420 g/kg CP) 47.10 Sunflower meal (300 g/kg CP) 78.59 Wheat bran 150.00 Wheal middlings 170.00

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