Page 14

FEATURE

Pea Seed protein concentrate in Tilapia feeds by Josh Cantril, Centre for Sustainable Aquaculture Research, Swansea University, Swansea, UK and Ingrid Lupatsch, Aqua Nutrition Manager, AB Agri Ltd

P

eas (Pisum sativum) are one of the four most important crops next to soybean, groundnut, and beans. It is a particularly important legume in temperate areas with numerous food (dry seed, vegetable) and feed (seed, fodder) usages. Field peas have attracted considerable attention as an animal feed due to increased production in Europe and Canada and thus reliable supply and competitive price. Peaseed meal has been trialed in Atlantic salmon, Rainbow trout and European sea bass with encouraging results. Peas, when unprocessed, contain moderate levels of protein 22-25 percent but also several anti-nutritional factors (ANF); however, the levels of ANFs in peas are low compared with other legumes and peas did not induce enteritis in the distal intestine in Atlantic salmon as seen when feeding soybean meal. New feed processing technologies have provided more suitable products for use in high protein aquafeeds. Pea protein concentrate (PPC) is produced by fine grinding dehulled peas into pea flour, followed by air processing which separates the particles based on differences in size and density. The resulting concentrate has higher protein and lower carbohydrate and

ANF contents compared with unprocessed peas, and thus would be a promising protein source in aquaculture feeds. The following study examined the efficacy and nutritional properties of peaseed protein concentrate as an alternative feed ingredi-

ent and protein source for all-male tilapia (Oreochromis niloticus) culture incorporating growth and digestibility trials.

Fish and rearing conditions

Genetically male Nile tilapia (GMT) were sourced as fry from Fishgen Ltd and raised at the Centre Table 1: Apparent digestibility coefficients (%) of fish meal and pea seed protein as for Sustainable Aquaculture determined in tilapia Research at Swansea Dry matter Protein Organic Matter Energy University until they reached % % % % the appropriate sizes to be Fish meal* 72.1 ± 0.2 89.5 ± 0.2 82.7 ± 0.3 83.7 ± 0.4 used in the trials. Fish were Pea seed concentrate** 73.2 ± 0.1 88.4 ± 1.8 79.3 ± 2.2 80.3 ± 2.3 cultured indoors as part of a freshwater recirculation system, which included mechaniTable 2: Formulation and composition of experimental feeds (per kg as fed) cal and bio-filtration units, a Ingredients Fishmeal 30% PPC 60% PPC 100% PPC protein skimmer and a sand Formulation filter. Water temperature Fish meal 605 410 210 was kept at 27°C and phoPea seed concentrate 165 340 520 toperiod was set at 12 hours Corn Starch 325 340 320 310 of light daily. Temperature Vegetable Oil 40 45 50 55 and dissolved oxygen levels were measured daily, while Vitamin &Mineral 5 5 5 5 total ammonia nitrogen, Di-calcium- Phosphate 25 55 nitrite, nitrate and pH were Calcium carbonate 25 55 measured weekly to assure Alginate 25 25 25 25 optimum water quality. Composition

Dry matter, g

927

905

903

910

Ash, g

133

98.7

92.9

88.8

Lipid, g

86.6

85.6

84.9

83.6

Crude Protein, g

393

390

393

397

Gross Energy, MJ

17.90

18.00

18.08

18.32

352

348

349

351

Digestible Energy*, MJ

Digestible Protein*, g

14.79

14.76

14.67

14.82

DP/DE ratio g/MJ

23.8

23.5

23.8

23.7

* Incorporating results from digestibility trial

12 | INTERNATIONAL AQUAFEED | September-October 2015

Feed preparation

Feeds were prepared according to Table 1 by mixing the dry ingredients with a binder and water, extruded through a meat grinder and afterwards dried at 450C for 24 hrs. The resulting pellets had a diameter of 2.5mm and 3.5mm for growth and digest-

Sep | Oct 2015 International Aquafeed  

The September October edition of International Aquafeed