Cost-ben­e­fit ad­van­tages of us­ing ex­truded feeds

Agriculture - - Contents -

NOWA­DAYS, fish farm­ers are con­fronted with the choice of us­ing ei­ther pel­leted feeds or ex­truded feeds. Those who do not know bet­ter may just se­lect pel­leted feeds on the ba­sis of price be­cause it is usu­ally cheaper than ex­truded feeds on a per kilo­gram ba­sis. Let us look into the cost and ben­e­fit by first clar­i­fy­ing the dif­fer­ence be­tween the ex­tru­sion process and pel­let­ing.

In both the ex­truder and the pel­letizer, the feed is pul­ver­ized. But the sim­i­lar­ity in the process ends there. In a pel­letizer the moist feed mix­ture is not nec­es­sar­ily cooked with steam or if cooked, this is done un­der nor­mal at­mo­spheric pres­sure. In ex­tru­sion, the moist mix­ture is cooked with steam be­fore it is ex­truded out with a screw into a die with a de­sired shape. The steam cre­ates a high pres­sure which makes it pos­si­ble to cook the feed at a higher tem­per­a­ture. With pres­sure above one at­mos­phere, the cook­ing tem­per­a­ture goes above 100°C. The higher tem­per­a­ture cooks the feed in­gre­di­ents more thor­oughly. The process is sim­i­lar to cook­ing meat in a pres­sure cooker which makes the meat more ten­der in a shorter pe­riod than when cooked in an or­di­nary pot. The pel­letized feed, even if sub­jected to steam in the process, can be con­sid­ered only half-cooked and have lower di­gestibil­ity rate due to the par­tially bro­ken bonds of mol­e­cules and the pres­ence of anti-nu­tri­tional fac­tors from plant in­gre­di­ents which lim­its the avail­abil­ity of sev­eral com­pounds, nu­tri­ents, vi­ta­mins, and min­er­als. The ex­truded feed on the other hand, is more fully cooked due to the higher tem­per­a­ture and pres­sure it is sub­jected to. This makes it more di­gestible and more of its nu­tri­ents is con­verted into flesh and tis­sues. This means a lower feed con­ver­sion ra­tio or FCR.

One big ad­van­tage of ex­tru­sion process which can eas­ily be seen even with­out spe­cial equip­ment is the high sta­bil­ity of the feed. Feed which are merely pel­letized are more crumbly and re­sults in more “pow­der” as a re­sult of han­dling. These fines are usu­ally blown away es­pe­cially when the wind is strong and are just wasted, thus, con­tribut­ing to more feed be­ing used, and there­fore a higher FCR.

Another ad­van­tage of the ex­tru­sion process, which again is eas­ily vis­i­ble, is the fact that ex­truded feeds can be made to float. This is very im­por­tant in fish cages. With ex­truded feeds, wastage is greatly min­i­mized and all of it are avail­able to the fish. Pel­letized feeds sink as soon as it be­comes wet when not im­me­di­ately in­gested by the fish. Upon sink­ing, they are no longer avail­able to the fish. This is not only a big waste eco­nom­i­cally but is also bad to the en­vi­ron­ment, be­cause they will in­vari­ably de­com­pose on the bot­tom.

Re­search has shown ex­truded feeds to be as much as 30% more avail­able than the pel­leted ver­sions of the same feed. The cook­ing process in­volved with ex­tru­sion im­proves di­gestibil­ity and avail­abil­ity of all nu­tri­ents in a feed in­clud­ing fiber, starch, pro­teins, min­er­als, and fats, re­sult­ing in higher ab­sorp­tion. The ex­tru­sion al­lows for much more fat to be added to feeds. It en­sures that in­gre­di­ents are get­ting into the fish and not be­ing wasted, so you feed sig­nif­i­cantly less feed. Ex­truded feeds vir­tu­ally elim­i­nate dust and fines. Less dust at the bot­tom of the bag means more nu­tri­ents ac­tu­ally get­ting into the fish, less waste and lower FCR.

The ex­tru­sion process breaks down the pri­mary bond hold­ing the chain of amino acids to­gether. The heat of ex­tru­sion also de­na­tures un­de­sir­able com­pounds such as ure­ase and the trypsin in­hibitor present in raw soy­beans.

The uti­liza­tion of car­bo­hy­drates is sig­nif­i­cantly en­hanced by the ex­tru­sion process. As starch is ex­truded, it is gela­tinized, and when it leaves the ex­truder, it ex­pands. Once the starch gran­ule is gela­tinized, it can­not re­vert to the orig­i­nal state and is wa­ter-sol­u­ble.

Dur­ing the ex­tru­sion process, oil from soy­beans and other raw in­gre­di­ents is re­leased from the seed cell, mak­ing the fat more avail­able for ab­sorp­tion. The oil helps ful­fill the fatty acid re­quire­ment and in­creases the en­ergy den­sity of the feed.

The high tem­per­a­ture dur­ing the ex­tru­sion process helps kill the micro­organ­isms in the feed that will cause de­cay. This ex­tends the shelf life of feeds from weeks to months. One of the big­gest hin­drances to ven­ture into aqua­cul­ture is cap­i­tal. Sev­eral new-com­ers, usu­ally not fully equipped with the ba­sic knowl­edge in the in­dus­try, think that they can save cost by us­ing cheap feeds like the pel­leted one. But due to the fact that FCR is higher in us­ing pel­leted feeds, the cost to pro­duce one kilo­gram of fish is in­creased. In­stead of sav­ing, the use of pel­letized feeds ac­tu­ally in­creases the cost of pro­duc­tion. In ad­di­tion to that, the risk of poor growth, pol­lu­tion and mor­tal­i­ties are higher with pel­letized feeds. On the other hand, ex­truded feeds sig­nif­i­cantly re­duce the feed cost by an av­er­age of 18.28 % and 16.80 % in milk­fish and tilapia, re­spec­tively, in in­ten­sive cage cul­ture sys­tems.

In the Philip­pine aqua­cul­ture in­dus­try, there is a glar­ing dif­fer­ence be­tween us­ing the two forms of feeds. In in­ten­sive milk­fish farm­ing, FCR us­ing pel­leted can be as high as 2.7-3.2 in ma­rine cages, while us­ing ex­truded feeds the FCR is as low as 2.0-2.5 when growing 10 grams ju­ve­niles to 500 grams har­vest size in high den­sity cages. If the av­er­age price of pel­leted feeds is 28 pe­sos a kilo, an av­er­age of R82.60 will be spent for feeds alone in every kilo of milk­fish. While if the av­er­age price of ex­truded feeds is R30 per kilo, an av­er­age of only R67.50 is spent for feeds to pro­duce a kilo of fish.

In the tilapia in­dus­try, the FCR is 1.9-2.3 for pel­leted feeds but only 1.5-1.8 with ex­truded feeds in high den­sity cages in Taal Lake (50-100 fishes per cu­bic me­ter at har­vest). If pel­leted feeds cost R28.20 per kilo, an av­er­age of R59.22 is spent for feeds to pro­duce a kilo of tilapia. On the other hand, if ex­truded feeds cost an av­er­age of R30 a kilo, you would only spend an av­er­age of R49.50 for feeds to grow a kilo of tilapia av­er­ag­ing 350 grams per fish.

Due to its bet­ter form, ex­truded feeds give even lower FCRs in ponds of both milk­fish and tilapia be­cause of bet­ter nu­tri­ents ab­sorp­tion, lesser waste in pond re­sult­ing to bet­ter wa­ter qual­ity, lesser cost of pro­duc­tion, and more profit.

It is clear that ex­truded feeds re­sult in higher prof­its and cleaner aquatic en­vi­ron­ment, all of which con­trib­ute to sus­tain­abil­ity of the aqua­cul­ture in­dus­try. Ex­tru­sion al­lows ef­fi­cient and in­creased use of plant in­gre­di­ents, thus, re­duc­ing the de­pen­dence on fish­meal com­ing from the sea. Waste and un­eaten feeds is re­duced by 27%33% more min­i­miz­ing the in­ci­dence of pol­lu­tion in the coastal and in­land waters.

Us­ing ex­truded feeds in any cul­ture sys­tem and species en­sures higher ef­fi­ciency, prof­itabil­ity and sus­tain­abil­ity. In aqua­cul­ture, be this for milk­fish, tilapia or even shrimps, the cost of feed­ing to pro­duce one kilo­gram of fish is what de­ter­mines prof­itabil­ity – not the price per kilo­gram of feeds. (TATEH NEWSFEED)

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