This document discusses rearing operations for silkworms, including disinfection, brushing, maintaining optimal temperature and humidity, care during moulting, mounting, and harvesting. It provides details on various physical and chemical disinfection methods. It also describes maintaining optimal temperature and humidity conditions for different stages of growth. Feeding schedules and quality of leaves fed to silkworms is addressed. Methods for mounting silkworms, collecting cocoons, and marketing cocoons are summarized. Metrics for evaluating cocoon quality like color, shape, size, compactness, and filament characteristics are outlined.

1. Rearing Operations
K.Kamatchi
Assistant Professor
Department of Zoology
Vivekananda College
Tiruvedakam West

2. •Rearing Operations
• Disinfection
• Brushing
• Maintenance of optimum temperature
• Maintenance of humidity
• Care during Moulting
• Mounting
• Harvesting

3. Disinfection:
Before selection
•Effective against pathogens
•Simple, easy, minimum time
•Harmless to man and animals
•Cheap and available.
•Physical
•Chemical

4. Physical methods
of disinfection
Sun drying
Steaming
Hot air
Chemical methods
of disinfection
Broad spectrum of activity
Non – toxic to others
Avoid – combination –
extraneous organic matter
Non-corroding – standing
Stable
Ready – mix – water
Detergent properties
No offensive odour
Large quantities – fair price

5. Chemical methods of disinfection
Spraying Formalin:
Colourless
Formaldehyde in water
35-40% formolde
Spraying with chlorkalk:
Ca, Cl and water
Bleaching powder
Surface of the worm – kill -UZi
Fumigation with forma gas:
Vapour of methyl alcohol
24 hours
Strong iritative odour
Formaldehyde in water
35-40% formolde

6. Burshing
• Hatching – Photoperiodic – sunshine
• New larve – black and bristly – ants
• Separating – larva – egg shell
• Transferring larva – rearing bed
• 10 a.m. – peak – hatching
Feather method
Husk method – powdered husk
Cloth / paper/net method

7. Maintenance of Optimum Conditions for
rearing
Temperature:
I – 26-28ºC
II – 26-28ºC
III– 24-26ºC
IV– 24-26ºC
V– 23-24ºC
Humidity:
I – 85%
II – 85%
III– 80%
IV– 75%
V– 70%

8. Feeding
Quantity of feeding:
Feed actively
Frequency of feeding
Varies – time – place
Six feeding – summer
Five feeding – other seasons
Quality of leaf
Preparation of leaf for
feeding

9. Bed Cleaning
Removal of wastes, unused leaves, residues and dead larvae
Methods
With husk
With net
Net and husk

10. Spacing
Mounting
Busy operation
5th instar
Methods of mounting
Hand picking
Simultaneous
Net
Branch
Free
Harvesting
Collection of cocoons
Methods

11. Cocoon Marketing
Early as possible
Before –moth emerge
Transport – centralised centres
Keep – closed container
Donot pack – too compact
Pupae will die –fluid oozing
Remove defective cocoons
Physical Characters of
Cocoons:
Price fixation
Colour – white, greyish
white, sliver white,
yellow, canary yellow,
golden yellow
Shape: round, oval,
spindle, peanut,
spherical
Size: numbers / litre,
300-400 /litre

12. Compactness or Haraness:
Silk content
Compact, elastic
Resilient between fingers
Grains or wrinkles
Irregularities on surface
Caused – conditions of rearing
Not reel – easily
Weight:
1.1 – 1.4 gms.
Shell weight:
0.15 – 0.25 gms
Shell ratio:
Weight of the cocoon shell
Weight of the cocoon
Length of the filament:
800-1200 m
Non-breakable filament length:
Weight of filament length
1 + number of breaks
• Filament Denier:
• Thickness of the filament
Weight of filament length
1 + number of breaks
• Floss percentage:
• Loose filament
• Unreelable
X 100
X 9000

13. Renditta:
No of kg of cocoon – 1 kg reeled
silk
6-8
Rew silk percentage:
Reelability: ratio of unbroken
filament.