Effects of culture density and feeding frequency on the growth performance, digestive enzyme activity and tissues histology in hybrid grouper (Epinephelusfuscoguttatus♀×E. lanceolatus♂)

Abstract

• A 6 week 5×2 two factorial experiment
  • 5 culture densities
    • 1.1 kg m−3(0.55 kg fish per tanks, CD1.1)
    • 2.2 kg m-3(1.1 kg fish per tank, CD2.2)
    • 3.3 kg m−3(1.65 kg fish per tank, CD3.3)
    • 4.4 kg m−3(2.2 kg fish per tank, CD4.4)
    • 5.5 kg m−3(2.75 kg fish per tank, CD 5.5)
  • 2 feeding frequencies(FF)
    • 2 meals a day (FF2)
    • 3 meals a day (FF3)
• growth performance
• body composition
• digestive enzyme activity
• tissues histology

ID	Density	Feeding Frequency
G1	CD1.1	FF3
G2	CD2.2	FF3
G3	CD3.3	FF3
G4	CD4.4	FF3
G5	CD5.5	FF3
G6	CD1.1	FF2
G7	CD2.2	FF2
G8	CD3.3	FF2
G9	CD4.4	FF2
G10	CD5.5	FF2

Result

Weight Gain	- High: G7; G1; - Lowest: G3; - FF2 > FF3
Muscle	- G8 > G2-G6 - No significantly different between G8 and other groups
Protein Content	similar like the muscle
Serum	- glutamic oxaloacetic aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG) and cholesterol (CHO) - Immune function: albumin (ALB), serum lysozyme (LZY), superoxide dismutase (SOD) and alkaline phosphatase (AKP) were significantly affected
Density	- pepsin and lipase in stomach, intestine and liver were significantly affected
Histological Structure	- Normal: G1, G2, G7 and G8 - Other groups were damaged to varying degrees

Introduction

graph LR;
    FF(daily feeding patterns);
    CD(intensive fish-farming);
    FC(growth performance);
    NC(nutritional conditions);
    SL(stress levels);
    MP(management procedures);
    WQ(water quality);

    FF-->FC;
    rhythms-->FC;
    CD-->FC;
    WQ-->SL;
    FF-->SL;
    rhythms-->SL;
    CD-->SL;
    NC-->SL;
    MP-->SL;

Feeding frequency

• regulating the feed intake
• growth and chemical composition
• reduction of aquaculture production cost
• preventing water quality deterioration

Challenge:

Overfeed:

• Canoverload: decreasing digestive efficiency and reductions

Insufficient FF:
poor growth; high mortality;

• sporadic feeding and low feeding rates may contribute to reduced growth as well as increased hunger, intraspecific aggression, and increased rate of cannibalism^[1]

Intensive

Intensive fish-farming practices often cause stress and poor health in fish.

• welfare
• aquaculture profitability

High Density

• stunts fish survival
• percentage weight gain
• specific growth rate
• physical
• injuries
• stress
• susceptibility to disease
• swimming behaviour
• intensify aggression

The results are attributed to social interactions competition for food and/or space^[2], leading to the establishment of hierarchies^[3].

Materials and Methods

Skip

Result

Discussion

• Weight

• Blood

• Muscle
  moisture in the muscle gradually decreased with the increase of CD
  Protein, fat and ash showed a gradual decline

• enzyme activities

  • pepsin activity and amylase
    activity FF2 > FF3
  • activity increased as the increase of CD except intestinal amylase

---

1. Folkvord A, Ottera H (1993).Effects of initial size distribution, day length, and feeding frequency on growth, survival, and cannibalism in juvenile Atlantic cod (Gadusmorhua L.). Aquaculture 114: 243-260 ↩︎

2. Lloyd M J , Bates A E . Influence of density-dependent food consumption, foraging and stacking behaviour on the growth rate of the Northern abalone, Haliotis kamtschatkana[J]. Aquaculture, 2008, 277(1-2):24-29. ↩︎

3. Cristina E. Trenzado and Manuel de la Higuera and Amalia E. Morales. Influence of dietary vitamins E and C and HUFA on rainbow trout (Oncorhynchus mykiss) performance under crowding conditions[J]. Aquaculture, 2007. ↩︎