Broiler feed is based primarily on corn and soybean meal (SBM). In most areas of the world corn is the predominant source of energy in feed because of its abundance and digestibility, roughly 60-75% of the total make-up of broiler diets is corn. Historically high corn prices, prompting nutritionists to search for other suitable raw materials to provide required nutrients for poultry to maintain productivity and to lower feed cost. Green algae (division Chlorophyta), found nearest the shore in shallow waters and usually growing as threadlike filaments, irregular sheets, or branching fronds, containing a number of relatively large forms (e.g., Ulva, Codium, Valonia, Halimeda) (Graham, 1984 GrahamL.E. 1984. Coleochaele and the origin of land plants. Am. J. Bot. 71:60-68.[Crossref] , [Google Scholar]). Ulva lactuca is known by the common name sea lettuce, the nutritive value of U. lactuca has been the subject of several studies. Seaweed shows great variation in nutrient composition which is related to several environmental parameters and ecological conditions such as water temperature, salinity, light, species, season of the year and the geographic area (Jensen, 1993 JensenA. 1993. Present and future needs for alga and algal products. Hydrobiologia 260/261:15-21.[Crossref], [Web of Science ®] , [Google Scholar]; Dawes, 1998 DawesC.J. 1998. Marine Botany. John Wiley & Sons Publ., New York, NY, USA. [Google Scholar]; Manivannan et al., 2009 Manivannan K. Karthikai Devi G. Thirumaran G. Anantharaman P. 2009. Mineral composition of marine macroalge from Mandapam coastal regions; Southeast Coast of India. Amer. Eurasian J. Bot. 2:42-51. [Google Scholar]). Several researchers investigated the nutritional value of seaweeds as an ingredient for broiler chickens without any adverse effects on performance. Asar (1972 AsarM. 1972. The use of some weeds in poultry nutrition. Degree Diss., University of Alexandria, Egypt. [Google Scholar]) indicated that supplementation of chicken’s basal diet with 4.0% seaweeds increased body weight gain. Maurice et al. (1984 MauriceD.V. JonesJ.E. DillonC.R. WeberJ.M. 1984. Chemical composition and nutritional value of Brazilian elodea (Egeria densa) for the chick. Poultry Sci. 63:317-323.[Crossref] , [Google Scholar]) concluded that sun dried Brazilian Elodea (Egeria densa) could be used in broiler diets at 5.0% without adversely affecting growth, feed conversion ratio (FCR) or dressing percentage. El-Deek et al. (1987 El-DeekA.A. AsarM.A. SafaaM.A. KosbaM.A. 1987. Nutritional value of marine seaweed in broiler diets. J. Agric. Sci. Mansoura Univ. Egypt 12:707-717. [Google Scholar]) found that inclusion of seaweeds in finisher broiler diets had no significant effects on growth, feed intake (FI) and FCR. Gu et al. (1988 GuH.Y. LiuY.G. ShuZ.Z. 1988. Nutrient composition of marine algae and their feeding on broilers. Chinese J. Anim. Sci. 3:12-14. [Google Scholar]) concluded that 2.0% of marine algae meal improved broiler performance and dressing percentage. Ross and Dominy (1990 RossE. DominyW. 1990. The nutritional value of dehydrated, blue-green algae (Spirulina platensis) for poultry. Poultry Sci. 69:794-800.[Crossref], [PubMed] , [Google Scholar]) found that the growth of the broilers fed diets containing up to 6.0% of Spirulina was not different from that of the chicks receiving the control diet. Ernest and Warren (1990 ErnestR. WarrenD. 1990. The nutritional value of Blue-Green algae Spirulina Plantensis for poultry. Poultry Sci. 69:794-800.[Crossref], [PubMed] , [Google Scholar]) observed that performance of male broiler chickens was not significantly affected by incorporation of blue-green algae up to 6.0% in the diet. Other reports indicated negative effects for seaweeds on broiler performance. Ventura et al. (1994 VenturaM.R. CastanonJ.I.R. McNabJ.M. 1994. Nutritional value of seaweed (Ulva rigida) for poultry. Anim. Feed Sci. Tech. 49:87-92.[Crossref] , [Google Scholar]) studied the effect of inclusion of U. rigida at 0.0, 10.0, 20.0 and 30.0% on chicken performance, it was reported that U. rigida decreased FI and body weight gain (BWG) and they concluded that it is harmful to be included in the diet at level higher than 10.0%. The objective of this study was to evaluate the effect of substituting 1.0 and 3.0% of corn with seaweed (U. lactuca) on performance, carcass characteristics, serum constituents and nutrients retention of broilers from 12 to 33 d.
Materials and methods
The study was carried out at the Department of Animal Production, Faculty of Food and Agriculture Sciences, King Saud University; Riyadh, Saudi Arabia under a protocol approved by King Saud University and complies with the current laws of Saudi Arabia.
Seaweed was handpicked and collected in April (2009) using scalpel from Mediterranean Sea shore of Alexandria, Egypt. The collected seaweed was from the species U. lactuca, green algae in the division of Chlorophyta. Collected seaweed was adequately washed with fresh water for 3 times to remove the salt, sun-dried for three days, and then oven-dried at 60°C for 72 h. Seaweed was ground to pass a 1.0 mm screen using Wiley mill grinder. Samples of U. lactuca were analyzed for gross energy (AOAC, 1990 AOAC, 1990. Official Methods of Analysis. 15th ed. Association of Official Analytical Chemists, Washington, DC, USA. [Google Scholar]), crude protein (N x 6.25) (AOAC, 1968 AOAC, 1968. Protein (crude) in animal feed. AOAC Official Method 968.06. J. AOAC Int. 51:766-770. [Google Scholar]), crude fibre (AOAC, 1982b AOAC, 1982b. Fiber (crude) in animal feed or pet food. AOAC Official Method 962.09. J. AOAC Int. 65:265-268. [Google Scholar]) and ether extract (AOAC, 1982a AOAC, 1982a. Fat (crude) or ether extract in animal feed. AOAC Official Method 920.39. J. AOAC Int. 65:289-292. [Google Scholar]). Minerals content were determined by inductively coupled plasma emission spectrometry (ICP) (method 990.08 AOAC). Chemical analysis and mineral composition of U. lactuca are presented in Table 1.
Animals and husbandry
One-day-old male chicks (Ross) were obtained from a commercial hatchery and randomly distributed among cages in electrically heated battery brooders with raised wire floors. The chicks had been vaccinated for Marek’s disease, Newcastle and infectious bronchitis. For the first 11 days, the chicks were fed a common starter mash diet that met the nutrient requirement suggested by NRC (1994 National Research Council, 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC, USA. [Google Scholar]). At 12 d, the chicks were grouped by weight in such a way as to reduce variation in mean chick weight and received the experimental diets. Five birds were randomly allotted to each of 15 cages; total number of birds used in this trail was 45. The temperature during the trial period was set at 22.0°C (actual temperature average during the trial period was 26.1°C). Feed and water were provided ad libitum and birds were maintained a 24-h light schedule.
Diets and treatments
Chemical composition of corn, SBM, and U. lactuca were determined and the adjusted values were used to formulate the experimental diets (Table 1). Corn was reduced at the expense of U. lactuca. Chicks were fed a standard corn-SBM starter from 1-to 11 d of age and on d 12 chicks were received 1 of 3 dietary treatments: T1, control diet and was formulated to meet a minimum of 100% of NRC (1994 National Research Council, 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC, USA. [Google Scholar]) requirements; T2, 1.0% U. lactuca; T3, 3.0% U lactuca. Diets 2 and 3 were formulated by substituting 1.0 and 3.0% of corn with U. lactuca, respectively. There was no attempt to make the diets isocalloric or isonitrogenous, the levels of other ingredients remained constant.
Feed intake and body weight (BW) were recorded weekly by pen and FCR computed at 19, 26 and 33 d. Mortality was checked daily and weights of dead birds were used to adjust FCR. At the conclusion of the trial at 33 d, two birds per cage were selected and kept without food for 12 h then were bled from cutaneous ulnar vein. Blood samples were collected in a 10 mL tubes (Iheukwumere and Herbert, 2003 IheukwumereF.C. HerberU. 2003. Physiological responses of broiler chickens to quantitative water restrictions: Haematology and serum biochemistry. Int. J. Poultry Sci. 2:117-119.[Crossref] , [Google Scholar]); blood samples were centrifuged using plain tubes at 5ºC and 3000 rpm for 10 min. serum was harvested and then transferred into eppendorf tubes and stored at -20ºC until further analysis, unless fresh sample is required for the analysis. The following analysis were conducted using enzymatic colorimetric kits (M, Europa GmbH, Hannover, Germany): total protein (Biuret method), albumin (Bromoreesol green method), globulin concentration was calculated, as the difference between total protein (TP) and albumin concentrations, total lipid (sulfo-phosphate vanillin method), cholesterol (Trinders color method), glucose (Modified trinder/GOD method), uric acid (end point method), sodium (Na+) (sodium dependent β-galactosidase activity), potassium (K+) (turbidimetric method), chloride (Cl–) (thiocyanate method); calcium (Ca++) (color/end point method) and zinc (Zn++) (colometric method). In addition, the following serum enzymes were determined by using UV/Kinetic method: alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT), lactate dehydrogenase (LDH), and creatine kinase (CK). All analyses were carried out in duplicate. The birds were processed using manual evisceration to determine dressing and parts yield. After euthanasia, feather, heads, necks, and shanks were removed, and the remaining carcasses were dissected to breast, thigh, drumstick, and abdominal fat and weighed. The percentage of yield of each part was calculated on the basis of dressed weight. Breast muscle color was measured by using color values for (L*) lightness, (a*) redness and (b*) yellowness, by Chromo meter CR-400 (Konica Minolta sensing Inc., Japan, B 8207175).
All statistical analysis was performed using the Statistical Analysis System (SAS, 2003 SAS, 2003. SAS Users Guide: Statistics, ver. 7.0. SAS Inst. Inc., Cary, NC, USA. [Google Scholar]). A cage constituted the experimental unit. Three dietary treatments were arranged in 5 replications in a randomized complete block design. Means for measurements showing significant differences in the analysis of variance were tested using the PDIFF option. Means ± standard error of the mean (SEM) are presented in the tables and differences were considered statistically significant at P<0.05.
Feed intake, BWG, and FCR of male broiler at different ages are shown in Table 2. At 26 and 33 d, no significant differences in BWG, FI and FCR were found due to treatment; similarly, cumulative FI, BWG and FCR from 12 to 33 d were not affected by treatment. However, a numeric improvement in BWG for birds which had received T3 was noticed (P=0.7). The mean percentage of carcass parts is documented in Table 3. Treatment had a significant effect on dressing percentage (P<0.004); birds which had received T3 had a higher dressing percentage compared to those which had received T1 or T2. While, there was no significant difference in dressing percentage between birds which had received T2 and T3. Breast muscle yield followed the same trend; heavier breasts were obtained from birds which had received T 2 or T3 (P<0.001). No difference in breast muscle yield was noticed between birds which had received T2 and T3. Thigh and drumstick (leg quarter) yield percentage was not significantly affected by treatment (P>0.05). Abdominal fat was reduced significantly (P<0.001) in birds which had received T3 compared to those which had received T1 or T2, a significant differences in abdominal fat percentage between T2 and T3 (P<0.05) was found. On the other hand, breast muscle color was not affected by any dietary treatments. The data related to serum biochemistry are shown in Table 4. Serum total lipid concentrations were significantly affected by treatment (P<0.05), serum from birds which had received T3 had the lowest concentration, while there was no difference between those fed T2 and T3 or T1 and T2. Serum cholesterol was reduced for T2 and T3 as compared to T1 (P<0.05). Serum total protein, albumin, globulin, and glucose were similar in all groups. Serum mineral contents were found to be similar among birds that had received the dietary treatments, Na+, K+, Na: K ratio, Cl–, Ca++, and Zn++ concentrations were not affected by any treatment (P>0.05). On the other hand, serum uric acid concentration was influenced by treatment (P<0.05), it was significantly higher for birds which had received the control diet compared to the other 2 treatments, no significant difference was found between those which had received T2 and T3. No significant difference in AST, ALP, GGT, LDH, and CK were found (P>0.05). The only enzyme that showed response to treatment was ALT, it was significantly higher for birds which had received T1 as compared to the other treatments (P<0.05) while it was similar between those fed T2 and T3.