الفهرس 
literature reviewOnly 14 pages are availabe for public view
 |  | from | 186 |  |  |
| | | from | 186 | | |
Abstract
ENGLISH SUMMARY
The present study was conducted in a private fish farm in west of Port Said in Port Said / Alex. international coastal road. This farm was constructed to occupy an area of 18 Faddans which were divided into 12 earthen ponds, rented from the General Authority for Fish Resources development (GAFRD). The farm is supplied exclusively with highly brackish water from the Mediterranean Sea and El-Manzalah Lake.
At the beginning of the fry season (middle of April), about 600 fry (1-1.5g initial body weight) were brought from the farm and reared under the normal farm feeding system (natural feed, minced trash fish, unmarketable tilapia from the fish collection market of Port Said) for 45 days in a rearing cage (3x3x1.5 m) with very small mesh size net.
Then fish were transferred to 3 cages (3x3x1.5m). All cages were placed near aeration machine. Fish were fed the experimental diets (G1, G2 and G3) once a day, 6 days a week. At the start of the experiment, 5 fish were taken and stored frozen for subsequent chemical analysis. At the end of the experiment, 5 fish per cage were sampled and kept frozen in the same way for the chemical analyses. At subsequent monthly intervals and at the end of the experiment, fish were individually weighed and measured. The trial was continued for 3 months.
Two synthetic diets with different crude protein (CP) contents [diet A (G2) 33% and diet B (G3) 37%] were formulated from local ingredients, except fish meal from Morocco. First, dry components were grinded and mixed very well, after that oil was added and mixed very well then each diet was packed separately.
The sinking diets A and B were pelleted in El-Max feed unit (Chinese production line ”man yong” operating by dry steam, grinding by pulverizer 10 micron, and the pump capacity is 3 ton / h) belonging to the fish experimental research station in Alexandria, National Institute for Oceanography and Fisheries. The diets were pelleted to 2 and 4 mm diameter. The 2 mm one was used at ages 3 and 4 months and the 4 mm one was used at ages 4-6 months.
The results obtained could be summarized in the followings:
1) Three experimental diets were tested in this study, mainly a natural diet (trash tilapia fish of 15.25 ± 1.02 g body weight, 9.25 ± 0.47 cm total length, 7.36 ± 0.38 cm standard length and 65.25 % dry matter content) and two artificial (external feeds) diets. The natural one consisted of minced tilapia fish. The other ones consisted of Morocco fish meal (60%), soybean meal (44%), gluten (60%), yellow corn, fish oil, dicalcium phosphate, and premix (vit. & min. mixture) to formulate 33 (A) and 37 (B) % crude protein (CP) diets. The proximate chemical analysis of the tested diets showed that the actual CP contents of the artificial diets on dry matter (DM) basis were lower (being 33.47 and 36.81 %, respectively) than in the natural feed (being 37.18 %). Also, the ether extract and ash percentages were lower, but the carbohydrates were higher than in the natural feed.
2) Fish rearing water criteria ranged between 23 and 25 °C throughout the experimental period (90 days), 7.7-8.0 pH, and 14.0-17.5 ‰ salinity, since the rearing water of Lake Manzalah is a brackish water coming from fresh water (inland drainage water) and Mediterranean Sea (marine water). These water conditions are the same where the local producers are used for culture of meager fish in Damietta governorate where the aquaculture of this fish species is widespread.
3) The growth performance of the tested fish cleared that there were no significant (P≥0.05) differences among dietary treatments for body weights and body lengths throughout the three experimental intervals (months). Yet, there were significant (P≤0.05) differences among intervals within each of the natural feed as well as the artificial feed B, with the best final BW and BL (after three months of the feeding period). Although the initial BW in the control (natural feed) was more than double that in the other two treatments and the initial BL in the control was longer than that for the other treatments; yet, the final BW after three months of the experimental feeding did not differ between the control and the artificial feed B, but the artificial feed A had lower final BW. Moreover, the final BL did not fifer among the three treatments.
4) The artificial diets, particularly, the artificial diet B (37 % CP) caused more gains in total bodyweights and daily bodyweights of the experimented fish during the whole experimental period. Generally, the absolute bodyweight gains, whether total or daily, increased by time duration.
5) The artificial diets, particularly, the artificial diet B (37 % CP) caused more gains (350-130 %) in total body length and daily body length (355-130 %) of the experimented fish during the whole experimental period. However, the absolute gains in fish length decreased by age ongoing in contrary to the bodyweight gains affecting the condition factor as will be illustrated there after.
6) The K-factor increased with age advance for the increase in weight than in length as mentioned before. The RGR decreased with age ongoing (in contrary to the absolute weight which increases by age) at the artificial diets, but increased by 238 % and 250 % on the artificial diets A and B, respectively comparing with control (natural feed). Also, the SGR decreased with age ongoing (in contrary to the absolute weight which increases by age) at the artificial diets, but increased by 162 % and 166 % on the artificial diets A and B, respectively comparing with control (natural feed). Again, The BLG decreased with age ongoing, but increased by 229 % and 240 % on the artificial diets A and B, respectively comparing with control (natural feed).
7) The artificial diets, particularly the diet B was the best, since it was responsible for lower FC by 13.6 %, better FCR by 31.5 %, more FE by 45 %, improved PER, PPV, and ER by 47.8, 12.9, and 31.6 % comparing with the natural feed (control diet).
8) Crude protein, ether extract and energy contents increased by age but ash content decreased generally. There were no significant (P≥0.05) differences among treatments for each criterion; yet, the artificial feeds, particularly B diet increased the CP and energy contents but decreased EE and ash contents comparing with the natural feed.
9) The artificial feeds increased the costs of producing one kg of bodyweight gain of the fish by 318 and 320%, respectively comparing with the natural feed. Yet, the same artificial feeds resulted in higher cost of bodyweight gain by 111.8 and 126 %, respectively comparing with the control (natural feed). So, both diets (A and B) were more efficient economically in producing BWG of meager by 357.3 and 403.7 %, respectively with the comparison with the control.
Conclusively, meager fish could be fed artificially pelleted diet (37 % crude protein), which enhance growth, feed utilization, body composition, and economics of producing this fish species more than the natural feed.
The profitability analysis of Argyrosomus regius farming in the earthern ponds at the western region of port said, Egypt was studied in fish farms located in the western region of Port Said (About 2579 feddans) provide the greater part of marine aquaculture production in Egypt. Almost all farms of this area are extensive polyculture earthern ponds, using fry exclusively from wild sources. The two species of mullet, bouri (Mugil cephalus) and tobar (Mugil capito), account for the majority of their output followed by meagre meagre (Argyrosomus regius), in addition to other species such as seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata). This study aimed to examine the economic potential of these farms using structured questionnaire. Data was collected from randomly selected 10 fish farmers during the period from March to October 2011. The collected data was analyzed using descriptive statistics, budgetary techniques and correlation analysis. The descriptive analysis showed that majority of farmers had either no schooling (40.0%) or medium schooling (40%). Almost all farmers (90%) feed their fish once daily. The majority finances their fish production through personal savings (70%). Profitability analysis revealed that the cost of feeds accounted for the largest proportion (68%) of the total cost of fish production followed by cost of fixed input and variable coast (12%), then fingerlings (7%) and labour (1%). Significant relationship was observed between fish production and labour, education status and ratio of used ponds. The results showed that fish production in the study area is economically rewarding and profitable.