FEATURE
Natural sources of cholesterol, phospholipids and proteins by Geert van der Velden, Carine van Vuure and Anke van Doremalen, Sonac BV, The Netherlands
A
quaculture is one of the fastest growing industries in food production. However, the future of this growth will depend largely on availability of raw materials and development of new nutrient sources from vegetable or animal origin. One of the essential nutrients for shrimp is cholesterol. Driven by the increasing scarcity of conventional sources of cholesterol, Sonac recently developed Phosterol. This hydrolyzed protein of animal origin is produced in accordance with all relevant EU regulations and is readily available from renewable natural sources. The uniqueness of Phosterol lies in the natural combination of cholesterol and phospholipids. Trails on shrimp have shown a strong synergy between cholesterol and phospholipids, the two main components of Phosterol. Phosterol is a unique protein hydrolysate with high content of cholesterol and phospholipids like phosphatidyl choline, phosphatidyl serine and phosphatidyl inositol. Cholesterol and phospholipids are essential building blocks in cellular membranes and are part of several biological processes. Together with the high amount of fat, Phosterol is a good ingredient in aquafeeds, especially shrimp feeds. Shrimps rely upon a dietary source of cholesterol for optimal molting. The origin of Phosterol is porcine tissue which has been collected in dedicated European slaughterhouses and after enzymatic hydrolysis further processed to a beige brownish and heat stable powder. Gelko Powder is a new hydrolysed animal-based product that contains highly digestible proteins for fish and shrimp. It hosts a combination of important amino acids, making aqua feed attractive and palatable. Naturally present nucleotides,
phospholipids and minerals increase its nutritional value.
Table 1: Composition of Phosterol and Gelko Composition
Phosterol
Gelko
Moisture
4%
4%
Crude Protein
48%
68%
EU Feed law According to EU Feed law, Phosterol and Gelko are permitted for use for all animal species. No limitations are imposed on production facilities, transport systems or use at farm level. No additional labeling texts are required.
Growth trial with Phosterol and Gelko Three diets were formulated to contain equal amounts of cholesterol. The reference diet contained crystalline cholesterol. One diet contained 0.9 % Phosterol and the third diet contained 2 % Gelko, a protein soluble (See Table 2). Feeds were produced with a pellet mill on a 2 mm die, using preconditioning with steam (>90째C) and post-conditioning (>90째C) for 20 minutes.
Shrimp trial The trial was performed at the AFTCreveTec research centre. Forty shrimp of 1-1.4 g were put in 12 nets of 150 litres. All nets were placed in a bigger tank, so all nets had the same water quality. Water quality in the big tanks was maintained with bioflocs. Each net was equipped with a feeder. The feed gift was adjusted daily according to an expected growth curve and average weight from initial and last measurement.
Results Growth (average weight) We can not observe a statistical difference in growth between the different feeds. Gelko seemed to be doing a little better in the middle of the experiment, but towards the end the Reference diet was the best. 46 | International AquaFeed | March-April 2013
Crude fat
34%
18%
Crude ash
9%
11%
Cholesterol
10%
0.10%
Total phospholipids
24%
9%
Phosphatidyl choline
7.80%
-
Phosphatidyl inositol
0.90%
-
DHA
2.30%
-
Table 2: Experimental diets - Diets were formulated to contain 38 % proteins and 8 % lipids. REF
Gelko
Phosterol
Corn gluten
5
5
5
Fish meal
26
24
26
Squid meal
2
2
2
16.9
16.9
16.9
Wheat flour
25
25
25
Soybean meal
15
15
14.2
Soyalecithin
2
2
2
Fish oil
2
2
2
Wheat Gluten
4
4
4
Premix
2
2
2
0.1
0.1
Wheat
Cholesterol Phosterol
0.9
Gelko Total
2 100
100
100
FEATURE Table 3: Growth of shrimp (g/week) on diets containing Phosterol and Gelko Week
1
2
3
4
5
6
Average
Reference
0.89
0 .41
1 .16
2 .00
2 .65
2 .39
1 .58
Phosterol
0.83
0 .43
1 .41
1 .63
2 .62
2 .15
1 .51
Gelko
0 .82
0 .52
1 .55
1 .75
2 .22
2 .44
1 .55
Overall, the observed growth was good, given the fact that shrimp were relatively small at the start of the experiment. Once they reached 3-4 g, they grow above 2g/week. Table 4: FCR of shrimp on diets containing Phosterol and Gelko Week
1
2
3
4
5
6
REF
0.81
2.02
1.18
1.39
0.99
1.36
1.18 b
Phosterol
1.09
1.81
0.69
0.87
0.86
1.41
0.99 a
0.7
1.71
0.76
0.98
1.61
1.17
1.07 b
Gelko
Total
The feed with Phosterol showed the best FCR, and was statistically better than the other diets Table 5: Summary of results Initial weight
Final weight
Growth (g/week)
Reference
1.31
10.81 a
1.58
Phosterol
1.17
10.25 a
Gelko
1.26
10.56 a
% Growth
Mortality
FCR
826 %
9.53 %
1.18 b
1.51
872 %
5.94 %
0.99 a
1.55
838 %
6.41 %
1.07 b
Conclusion Phosterol is a valuable alternative source of cholesterol and gives similar results in growth and lower FCR than the pure source. It also shows lower mortality. Gelko can replace high quality fish meal with a minimum of 2 % with no growth loss, and results in a lower mortality. Due to the composition, Phosterol has many benefits in aquafeeds: • Fat and protein mixture • Rich in cholesterol (10%) • Rich in phospholipids (24%) • Good suspension • Good emulsifier • Attractant and palatant in shrimp diets • Improved growth rates, molting frequency and survival in farmed shrimp • Cholesterol is heat stable (3 hours 133°C) The advantages of Gelko: • Fat and protein mixture • Rich in phospholipids (9%) • Good suspension • Attractant and palatant in shrimp diets • Soluble proteins with extreme high digestibility More Information: Website: www.sonac.biz
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March-April 2013 | International AquaFeed | 47