Processed feed pea and canola meal for blue shrimp diets

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L.E. Cruz-Suarez et al.rAquaculture 196 2001 87–104
meal Ž WRA and DRA ., the extruded canola meal Ž CEX.
and control diets showed
intermediate consumption. Weight gain of the experimental animals practically tripled
after 28 days for each of the dietary treatments. With the exception of the micronized
pea Ž WMI dietary treatment ., there were no significant differences in weight gain among
the dietary treatments. A food conversion ratio of less than 2 was obtained for each of
the dietary treatments. Significantly lower feed conversion ratios were obtained for the
extruded pea meal diets, perhaps due to improved starch digestibility. The highest PER
values were also obtained for the extruded pea meal diets indicating that protein
utilization was not impaired by the effects of heat treatment. Correction of DFI for
losses in sea water before the feed ingestion led to improved values of FCR and PER,
but relative differences among the means for the different treatments were not modified
substantially, since homogeneous subsets as defined by the Duncan’s multiple comparison
test remained the same. Survival for all treatments Ž above 90% . was excellent and
did not differ significantly amongst diets. The largest biomass gain was obtained for
shrimp fed the WMI micronized pea and control diet, due mainly to the weight gains of
these groups.
3.3. Digestibility
The apparent dry matter digestibility Ž ADMD.
for the experimental diets was
generally higher than that of each of the reference diets Ž Tables 5 and 6 .. The ADMD
and apparent protein digestibility Ž APD.
amongst the experimental growth study diets
Ž 1–6.
were not significantly different. Apparent dry matter and protein digestibility
values for the test ingredients calculated using reference diets Ž 8 and 9.
and following
the method of Cho and Slinger Ž 1979.
are also presented in Tables 5 and 6. The
adjustment of the digestibility coefficients for leaching losses Ž Table 6 vs. Table 5.
did
not change the statistical inference to the treatment effects. However, in the subsequent
calculation of the carbohydrate digestibility, it was noted that the adjusted coefficients
supported more realistic values that would indicate the correction to be necessary,
especially for the extruded canola meal Ž Table 5 .. The highest dry matter digestibility
values were obtained with the extruded pea flours and the lowest with micronized pea
meal and extruded canola meal. Similarly, adjusted digestibility of carbohydrate as
expressed by NFE Ž Table 6.
was close to 100% for the pea ingredients and canola
except for DRA and WMI Ž 87.4% and 85.5% .. In contrast, there were no significant
differences in IAPD among the differently processed pea meals and canola meal.
However, in spite of these relatively uniform protein digestibility values, and lower
carbohydrate digestibility for the micronized pea, the feeding trial results show best
performance with the WMI treatment. Therefore, the benefit derived from micronizing
peas is apparently due to enhanced feed intake rather than an improvement in nutritional
value.
Metabolizable energy calculations led to higher values for extruded pea meals
Ž 16.2–16.4 kJrg. than for raw pea meals Ž 15.4–15.6 kJrg ., and lowest values for
micronized pea and canola Ž 14.0 and 14.2 kJrg, respectively. Ž Table 6 .. Metabolizable
energy was lower than digestible energy by only about 0.4 kJrg, for all the experimental
ingredients.