عنوان مقاله [English]
Introduction: The purpose of this trial was to investigate the effects of adding Spiralina platensis algae in layer diets on the performance, intestinal microflora and morphology, and some blood parameters. The recent trend in the feed business is currently directed toward the use of natural ingredients as alternativest antibiotics, synthetic colors, and other chemicals. Spirulina platensis algae is one of the high quality natural feed additives that can be used in animal and poultry nutrition. There are two different species of spirulina: Spirulina maxima and spirulina platensis, with varying distribution throughout the world (Oliveira et al, 1999). Spirulina maxima, contains high levels of vitamin B1, vitamin B2 and β- carotene, and up to 71% crude protein with sufficient concentrations of all essential amino acids except for the sulfur-containing ones (Becker, 2004). Spirulina platensis dried supplement has an excellent nutritional profile. It has increased level of protein with values ranged between 55- 65% and includes all of the essential amino acids, high carotenoids, and rich in minerals and vitamins (Ross and Dominy, 1990). Spirulina contains up to 20 percent of phycocyanin, a water-soluble blue pigment and green pigment chlorophyll a, and relatively high content of vitamin B12 (Ciferri and Tiboni, 1985). Spirulina platensis is the source of essential fatty acid, γ-linolenic acid (Abd El-Baky et al, 2003). Spirulina platensis also has minerals, magnesium, manganese, iron, calcium, chromium, copper, phosphorus, potassium, sodium and zinc (Belay, 1997). The available energy content of Spirulina platensis has been determined to be 2.50-3.29 kcal/gr and its phosphorous availability is 41% (Yoshida and Hoshii, 1980).Verma et al (2004) reported that Spirulina platensis inclusion in broiler diet at 1 percent showed profound antioxidant effects in term of increased activity of erythrocyte antioxidant enzymes and decreased serum lipid peroxidation. Hens fed with diets supplemented with varying levels of Spirulina platensis tended to decrease the cholesterol content in the egg yolk of hens (Sakaida, 2003). The addition of 1.5 to 12% of spirulina platensis into the diets for broilers can replace other protein sources given to broiler, especially soybean meal, as the former shows satisfactory growth rates and feed efficiency (Nikodemusz et al, 2010).
Material and methods: A total of 192 LSL hens aged from 26 to 37 weeks were used in a completely randomized design with 4 treatments and 4 replicates and 12 hens per replicate. The treatments consisted of feeding a corn-soybean meal control diet alone or supplemented with 1.5, 3 or 4.5% Spirulina platensis. Cages were ventilated in a way that daily temperature was maintained between 21˚C and 23˚C. Each cage was equipped with feeder and drinker. Feed and water were provided ad libitum. A standard LSL diet was fed, containing (calculated): 17.6% CP, 0.42% Met, 0.82 Lys, 4.1% Ca, 0.6 Available P, and 2770 kcal ME/kg. During the experimental period, a 16-hour lighting schedule was applied. Performance including feed intake, feed conversion ratio, egg production, and egg mass weekly were calculated over the period. After feeding the experimental diets for 12 weeks blood parameters included cholesterol, triglycerides, HDL, and LDL were analyzed. In addition, villi height, crypt depth, villi height to crypt depth ratio, epithelium width and villi surface and also intestinal microflora (coliform, lactobacillus and total bacterial population) were measured. Statistical analysis used in this study was performed in completely randomized design using GLM procedure with SAS software and comparison of means by fisher's protected LSD test. A P-value of less than 0.05 was considered significant, unless otherwise stated.
Results and discussion: The results showed that experimental treatments had no significant effect on feed intake, feed conversion ratio, egg production and egg mass. According to the present study, Zahroojian et al (2013) reported that egg qualitative and performance traits of laying hens were not affected by diets containing spirulina platensis. In contrast, Shanmugapriya et al (2015) reported that body weight gain and feed conversion ratio increased significantly by adding 1% spirulina platensis to the broiler diet compared to the control treatment. The reason for this discrepant is likely due to the inclusion of different levels of spirulina platensis and the age of the birds used (Bonos et al, 2016).
Addition of spirulina platensis to the laying hens diet had no significant effect on cholesterol, triglyceride and LDL, but HDL levels was decreased significantly in third and fourth treatments (p < 0.05). Shanmugapriya et al (2015) reported that in broiler fed 1.5% spirulina platensis and saccharomyces cerevisiae, serum cholesterol and triglyceride levels decreased but HDL levels increased compared to the control treatment. These results are inconsistent with the findings of the present study which may be due to the use of low levels of algae. In addition, the condition of cultivation and processing of algae that are effective in their composition may be another reason for this inconsistency (Gutierrez–Salmean et al, 2015). Experimental treatments had no significant effect on villi height, villi height to crypt depth ratio, villi surface and epithelium width, but the crypt depth was significantly increased in the fourth treatment (p < 0.05). The use of red seaweed algae in brown luhman laying hens diet increased the villi height and crypt depth compared to the control treatment (Kulshreshtha et al, 2014). Also, the use of different levels of spirulina platensis had no significant effect on coliforms, lactobacillus and total bacterial population.
Conclusions: The present findings show that, supplementation of Spiralina platensis by 4.5% in the diet, had no effect on performance of laying hens and high levels of that are likely to needed.