Processed feed pea and canola meal for blue shrimp diets

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92 ( ) L.E. Cruz-Suarez et al.rAquaculture 196 2001 87–104 gain. rŽ protein intake .; survival Ž %S. s100= Ž final count. rŽ initial count. and tank biomass Ž B. sŽ sum of the individual shrimp weights present in the tank .. Taking into account the loss of dry matter and protein due to submersion in seawater, corrected values were calculated multiplying the standard DFI and FCR expressions by Ž 1y%DMLr100. and dividing the standard PER expression by Ž 1y%CPLr100 .. 2.4. Digestibility determination The digestibility study was carried out with a separate lot of shrimp obtained from Aquastrat Ž Sinaloa, Mexico ´ ., which had an average weight of 2.7 g and were distributed, eight per tank, in two blocks of eight dietary treatments Žsix test dietsqtwo reference diets .. The collection period was repeated twice to obtain four samples per dietary treatment, considered as four replicates. The shrimp were fed once a day at a fixed daily ration of 0.5 grtank for the first two replicates, and 1 grtank for the other two replicates. After removing uneaten feed, feces were collected at 90, 120 and 150 min after feeding, for a sufficient number of days Ž 4–8. to pool 1 g feces per sample Žwet weight .. The feces were collected by siphoning, rinsed immediately with distilled water and stored frozen. The samples were analyzed for chromic oxide by the method of Bolin et al. Ž 1952 .. Nitrogen was determined by a modified micro-Kjeldahl method ŽNieto- Lopez ´ et al., 1997. in a Tecator equipment using the Bolin reagent. The apparent dry matter and protein digestibility of diets Ž %ADMD and %APD, respectively. were calculated by the equations Ž Maynard et al., 1981 .: %Crin diet %ADMDs100y100= %Crin feces %CPin feces %Crin diet %APDs100y100= = %Crin feces %CPin diet Ž . where %Cr and %CP are chromium and protein concentrations % of dry matter . Additionally, apparent digestibility values were adjusted for losses by leaching before feed ingestion, according to the following equations, in which dry matter or protein intake is corrected: %Crin diet 1 %ADMDadj.s100y100= = %Crin feces Ž 1y%DMLr100. %CPin feces %Crin diet 1 %APDadj.s100y100= = = Ž . %Crin feces %CPin diet 1y%CPLr100 Apparent digestibility of the ingredient to be tested was determined by the method of Cho and Slinger Ž 1979 ., where the test ingredient Ž TI. replaced 30% of the complete formula of the reference diet Ž RD .. Accordingly, the reference diets Ždiets 8 and 9, Table 2. were used to calculate the digestibility coefficients of pea meals and canola meal, respectively, in the test diets Ž TD .. Ingredient’s apparent dry matter and crude protein
( ) L.E. Cruz-Suarez et al.rAquaculture 196 2001 87–104 93 digestibility values Ž %IADMD and %IAPD, respectively. were calculated by the equations: Ž 100=%ADMDin TD. yŽŽ 100y%TI . =%ADMDin RD. %IADMDs %TI Ž 100=%APDin TD=%CPin TD. yŽŽ 100y%TI . =%APDin RD=%CPin RD. %IAPDs %TI=%CPin TI where %CP in diet or test ingredient, and the inclusion level of the test ingredient Ž %TI. are expressed on a dry matter basis. The apparent digestibility of the nitrogen free extract in diets or ingredients Ž ANFED. was calculated from the ADMD and APD values, and from assigned values of 90% for lipids digestibility Ž Cruz-Suarez ´ et al., 1999 ., 50% for ash digestibility Ž Bureau, 2000. and 0% for crude fiber digestibility: ANFEDs Ž %drymatter=ADMDy%CP=APDy%lipid=90y%ash=50. r%NFE 2.5. Metabolizable energy estimation The metabolizable energy content of the experimental ingredients were calculated by using the Aaverage productive valuesB proposed by Cuzon and Guillaume Ž 1997. as energy coefficients assigned to the digestible energy sources, as follows: MEkJrgsŽ 17.2= wNFE x=IANFEDadj. . qŽ 39.5= wlipid x=IALD. qŽ 21.3= wprotein x=IAPDadj. . where wNFE x, wlipidx and wproteinx are nitrogen free extract Žassumed to be available carbohydrate ., crude lipid and crude protein concentrations of the ingredient, and IANFEDadj., IALD Ž s0.9 ., IAPDadj. are the respective apparent digestibility coefficients. 2.6. Statistical analysis The responses calculated for each tank Žmean body weight, biomass, growth rate, survival, food intake, food conversion, protein intake, PER and digestibility. were subjected to an analysis of variance and to the Duncan’s multiple range test ŽSteel and Torrie, 1988. to first determine whether significant differences existed among the experimental diets and then to identify where they occurred. In addition, a factorial analysis of variance was carried out on the raw and extruded, and whole and dehulled pea meal dietary treatments Ž statistical program SPSS for Windows, release 8.0.0 ..
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Processed feed pea and canola meal for blue shrimp diets

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