February 15-18, 2009 Washington State Convention Center Seattle ...

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REPLACEMENT OF FISHMEAL WITH POULTRY BYPRODUCT MEAL IN DIETS FOR
JUVENILE BLUEGILL Lepomis macrochirus
Karthik Masagounder*, Robert S. Hayward and Jeffre D. Firman
Department of Fisheries & Wildlife Sciences
University of Missouri
Columbia, MO 65211 USA
kmb6b@mizzou.edu
A 60-d trial was conducted to determine the percentage of fish meal that could be replaced by poultry byproduct meal (PBM)
in the diet of juvenile bluegills Lepomis macrochirus (~18 g initial weight) without affecting their growth performance. A
control diet contained 54.6% of fish meal (Table 1). Fish meal from the control diet was progressively replaced with PBM at
20% increments from 0% to 100%, resulting in six diets containing PBM at 0% (PBM0), 10.9% (PBM20), 21.8% (PBM40),
32.7% (PBM60), 43.6% (PBM80), and 54.6% (PBM100) levels. Gross energy levels in the six diets ranged from 18.3 MJ Kg -1
(PBM0) to 19.5 MJ Kg -1 (PBM100). Total amino acid content of the diets ranged from 41 % (PBM0) to 43 % (PBM100). Under
a randomized complete block design, bluegills (n=16/group) were housed individually in plastic test chambers and fed twice
daily at 4% (days 0-30) or 3% (days 30-60) of body weight. Pellets from diet 3 (PBM40) with 40% replacement of fish meal
exhibited low water stability due to an error that occurred in the extrusion program. Consequently, fish that were fed this diet
were excluded from statistical analyses. Data analyses on weight gain (g), Wr (%), hepatosomatic index (HSI), viscerosomatic
index (VSI), visceral fat (%) showed no differences (P>0.05, ANOVA) among dietary groups for any of the metrics (Table 2).
Study results indicate that fish meal can be completely replaced by PBM without affecting growth performance or well-being
of juvenile bluegill reared for 60 d.
Bluegills are aggressive fish and are known to form strong dominance hierarchies when held in groups. This often results in a
few individuals acquiring a high percentage of the feed provided, and the remaining fish receiving much less. Consequences
of dominance hierarchy formation include reduced mean growth and feed efficiency, as well as increased size variation among
bluegills in a tank/chamber. Therefore, the current experiment concerning effects of PBM replacement was conducted with
bluegills that were housed individually. However, we observed that some individually housed bluegills were reluctant to feed
initially, and this factor produced poor overall feed efficiency (~0.5). A similar PBM experiment with group-housed bluegills is
underway to determine whether results based on individually-held bluegills will lead to different conclusions than when groupheld
bluegills are evaluated.
Table 1. Formulations of control diet. Table 2. Final weight (g), weight gain (g), viscerosomatic index (VSI), hepatosomatic
Ingredients g Kg -1
Fish meal 545.5
PBM 0.0
Wheat 246.4
SBM 120.0
Fish oil 74.7
Lecithin 3.0
Vitamin premix 2.5
Dicalcium
2.0
phosphate
Choline-Cl 1.4
Mineral premix 1.0
Vitamin C-PP 0.7
Binder 2.8
Variable
index (HSI), final relative condition factor (Kn), and visceral fat content (%) of juvenile
bluegill fed the the five experimental diets for 60 days. Values are presented
PBM0
(n = 15)
as means±SE.
* n =3 for visceral fat analysis
PBM20
(n = 16)
PBM60
(n = 15)
PBM80
(n = 16)
P-value
PBM100
(ANOVA,
(n = 14)
proc glm)
Final weight (g) 48.8±3.2 44.2±2.0 41.0±1.9 42.7±2.2 43.6±2.2 0.36
Weight gain (g) 30.4±2.9 25.9±1.6 24.8±1.8 26.1±2.2 25.4±2.1 0.49
VSI (%) 12.3±1.1 14.9±1.0 14.0±1.1 14.3±1.5 15.0±1.6 0.33
HSI (%) 0.9±0.1 0.4±0.1 1.1±0.1 0.5±0.1 1.0±0.1 0.33
Wr (%) 109.9±2.5 106.9±2.8 107.8±2.5 108.1±3.3 106±2.0 0.90
Visceral fat (%)* 46.7±2.2 39.5±3.1 44.5±2.8 47.3±1.5 42.4±0.9 0.17