EFFECTS OF DIETARY MIXED OILS ON SOME PRODUCTIVE PERFORMANCE AND STEROID HORMONES IN LAYING HENS

A.M.M. Hamdy¹, N.M. Esa²   and E.A. EL-Malt ³ 

1- Animal Production Department, Faculty of Agriculture, Minia University, Egypt

2- Animal production Research Institute, Dokki, Egypt

3- Agriculture Chemistry Department, Faculty of Agriculture, Minia University, Egypt

SUMMARY

A total number of sixty Fayoumi hens at 30 weeks of age were used in this study to evaluate the effects of dietary mixed oil on some productive performance and steroid hormones. The hens were randomly divided into four equal groups. Hens of each group were subdivided into three replicates.  All hens were fed a basal diet contained 16% crude protein, 2798 Kcal ME /kg, 3.4% calcium and 0.88% total phosphorus. Hens of group 1 were served as control, while those of group 2, 3 and 4 were fed a basal diet supplemented by  oils mixture at 1,2 and 3% (W/W), respectively. The mixture of oils used was cottonseed oil: sunflower oil (1:1). The experiment was continued till 40 weeks of age.

Egg production  (number and weight) was recorded daily per replicate. Within each replicate weekly feed intake was determined and feed conversion (feed: egg) was then calculated. At 30, 35 and 40 weeks of age, blood samples were collected from five birds from each treatment. Serum progesterone (P₄) and estradiol (E₂) concentrations were determined.

The obtained results revealed that supplementing Fayoumi laying diet by oil mixture improved (P<0.05) the egg number, egg weight and feed conversion.

Meanwhile, feeding laying hens with applied mixed oils significantly increased serum concentrations of progesterone (P4) and estradiol (E2).  Moreover, there were no significant differences between the levels of  mixed oil  2% and 3% on the serum  P₄  and E₂  concentrations.

Key words: Dietary oil, reproductive performance, and steroid hormones, laying hens.

INTRODUCTION

Apart from storing and transporting forms of metabolic fuel, the fatty acid portion of dietary oil serves several important functions in the body. These include providing  the essential fatty acids requirements, acting as structural components of cell membranes, and serving as precursors for eicosanoid production.  Whitehead and Herron (1988) reported that linoleic acid requirements for normal physiological function in poultry seem to be  10gm/ kg diet;  however, requirements are more difficult to establish in adult birds because of reserves accumulated during rearing and laying. They also noted that responses in egg weight of hens were originally attributed to an effect of high dietary contents of linoleic. Eicosanoids, such as prostaglandin’s and leukotrienes, are recognized as important modulators of cell mediated immunity and humoral immunity (Kinsella et al., 1990). Considerable evidence had suggested that dietary oils may influence the immune response through their ability to modulate eicosanoid production (Fritsche, et al., 1991).  The effects of dietary polyunsaturated fatty acid on the regulation of lipid metabolism and the level and composition of body fat appear to be diverse. Vegetable oils such as cottonseed oil and sunflower oil are known to inhibit lipogenesis (Pinchasov and Nir, 1992). It is widely recognized that the fatty acid moieties of phospholipids determine many membrane functions. Acid oils are composed of between 75 and 95% of total fatty acids from the original oil or fat; they are present primarily as free fatty acids with a variable amount of triacylglycerols. The remaining material has not been well defined, but is likely to consist of oxidized fatty acids, phosphates, sterols, tocopherols, carotenoids, pigments and other minor fat-soluble constituents (Vila and Garcia, 1996)

The objective of the present study was to determine the effect of feeding a mixture of cottonseed oil and sunflower oil on some reproductive performance and steroid hormones in Fayoumi chickens.

MATERIALS AND METHODS

A total number of sixty Fayoumi hens at 30 weeks of age were used in this study to evaluate the effect of dietary mixed oils on some reproductive performance and steroid hormones concentrations. Hens were nearly similar in body weight (1567 ± 23.2) gm. The hens were divided randomly into four equal groups. Hens of each group were subdivided into three replicates.  All hens were fed a basal diet (Table 1) contained 16% crude protein, 2798 Kcal ME /kg, 3.4% calcium and 0.88% total phosphorus  (NRC, 1994). Hens of group 1 were served as control, while those of group 2, 3 and 4 were fed a basal diet supplemented by mixture of oil at 1,2 and 3% (W/W), respectively. The C/P ratio was ranged from 174.65 to 180.88 for the four experimental diets. The mixture of oils used was cottonseed oil: sunflower oil (1:1).  Fatty acids methyl esters were prepared, for the four experimental diets, from extracted lipid according to the method described by Metcalfe et al., (1966); and analyzed for fatty acids using gas chromatography GC apparatus according to Paquot and Hautfenne (1985). Then the ratio of unsaturated to saturated fatty acids were calculated (USFA/SFA). The experiment was continued till 40 weeks of age.

Egg production  (number and weight) was recorded daily per replicate. Within each replicate weekly feed intake was determined and feed conversion (feed: egg) was then calculated.

At 30, 35 and 40 weeks of age, blood samples were collected from brachial vein of 5 birds from each treatment. Blood samples were immediately centrifuged at 3000 rpm for 20 min and serum was stored at -20°C till analysis. Direct radioimmunoassay (RIA) technique was performed to determine steroid serum hormones. Ready antibody coated tube kits for the manufacturer used chickens (Diagnostic Product Corporation, Los Angelos) according to the procedure outlines.  Serum  progesterone (P₄) and estradiol (E₂) were determined according to Etches et al (1981). The means of intra-assay coefficient of variations were 3.2% and 4.4% for P₄ and E₂, respectively. Blood samples were betided to be from 7 to 7:30 am.

Data were statistically analyzed by the analysis of variance with the General Linear Model (GLM) procedure of the SAS Institute (SAS, 1992). All statements of significance were based on the 0.05 level of probability. Significant differences among groups were analyzed using Duncan’s multiple range test (Duncan, 1955).

Table 1. Composition of the experimental diets.

* Dietary mixed oils = Cotton seed oil: sunflower oil (1:1).

** Each  1 Kg contains: Vit. A 12000 IU, Vit. D 2500 IU, Vit. E 10 mg, Vit. K 3 mg. Vit B1  1mg, Vit. B2  4 mg, Pantothenic acid  10 mg Folic acid  1 mg, Niacin  40 mg,Vit. B6  3 mg, Vit. B12  20 mg, Mn 62 mg, Fe 44 mg, Zn  56 mg, Cu  5mg and Se 100 цg

USFA: Unsaturated fatty acids.               SFA: Saturated fatty acids.

RESULTS AND DISCUSSION

1-Productive performance:

Data  of productive performance are listed in Table 2.  The obtained data revealed that supplementing the Fayoumi laying diet by mixed oil improved  (P<0.05) egg number and egg weight than the control. The increase was linear by increasing the dietary oil level. While analyzed data showed that there were no significant differences between levels of 2 and 3% of dietary oil on egg number and egg weight.  These findings are in agreement with those reported by Sturkie (1986); Whitehead and Herron (1988); Fritsche, et al., (1991) and Friedman and Sklan (1995), they reported that feeding different dietary fat sources was reflecting in the fatty acid composition in some lymphoid tissues as well as liver.  This may encourage the synthesis of steroid hormones, which led to improve reproductive performance (egg number and egg weight).

Data of feed intake and feed conversion indicate that, feed intake decreased while feed conversion increased by increasing the level of dietary oil. Reddy et al., (1980) and Boulos (1983) found that feed consumption decreased as the dietary energy level increased. Therefore, with isonitrogenous diets, the daily protein intake increases as the dietary energy level decreases. Attia (1986) concluded that feed conversion to eggs improved (P<0.05) by increasing the dietary energy level. 

Table 2. Mean ± SE of egg number, egg weight, feed intake and feed conversion as 

              affected by dietary mixture oil supplementation.

*Dietary mixed oils = Cotton seed oil: sunflower oil (1:1).

Means in the same row with no common superscript are differ significantly (P<0.05).

E.No : Egg number     E.Wt: egg weight      FI: Feed intake        FC: Feed conversion

2- Serum steroid hormones:

            Data in Table 3 show the blood serum concentration of progesterone (P₄) and estradiol (E₂) in the four experimental groups.  The obtained results showed gradual increase in P₄ and E₂ concentrations with advancing in age till 40 weeks of age.  Moreover, it was observed that hens fed mixed oil at levels of 2 and 3% recorded (P < 0.05) higher serum P₄ and E₂ than those of control or that fed 1% mixed oils. Furthermore, it was noticed that increasing the steroid serum concentrations are paralleled with the increase of USFA/ SFA ratio.           The levels of steroid serum constituents are quite different in laying hens when various reproductive states are compared. The levels of these constituents are under the control of circulating hormones that are related to metabolism. The developing oocyte utilizes blood cholesterol carried by triacylgylcerol-rich lipoprotein and vitellogenin (Hall and Mckay, 1994).  Hamdy (2000) reported that fatty acid composition is a major precursor in the biosynthesis of steroids.

Table 3.  Means ± SE of serum progesterone (P₄) and estradiol (E₂) as

                affected by dietary mixture oil supplementation.

*Dietary mixture oils = Cotton seed oil: sunflower oil (1:1).

Means in the same row with no common superscript are differ significantly (P<0.05).

            The increase in serum P₄ concentration might be related to the increased release of gonadotropin hormones from pituitary gland. Etches et al (1981) reported a relationship between the release of gonadotropin hormones and its stimulation to ovarian follicles progesterone secretion. While the significant increase in serum E₂ concentration at peak of egg production (30-40) weeks of age may be due to the association between estradiol level and yolk protein formation. Tixier-Biochard et al (1990) came to similar observations.

From these results, it could be concluded that supplementing the laying hens diet with mixture of oils improve the productive performance as well as steroid hormones.

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