ANN 121: Applied Animal Nutrition-I (2+1)

MEASUREMENT OF DIGESTIBILITY BY IN VITRO METHOD (TILLEY AND TERRY METHOD)

Aim

• To find out the digestibility of given feed sample by in vitro method.

Principle

Apparatus

1. Conical Flask, 100 ml
2. Water bath
3. Cork with Bunsen valve
4. Filter paper / Crucible
5. Oven
6. Carbon dioxide gas

Reagents

i) Phosphate-carbonate buffer (Mc Dougall, 1948)

NaHCO

Na

KCl                   0.57 g

NaCl                 0.47 g

MgSO

CaCl

• Mix the above chemicals except CaCl
• 2 in 800 ml distilled water in 1 litre volumetric flask, stir to dissolve and make the volume to one litre. Just before use, add CaCl2, Keep at 39oC and pass CO2 through the solution.

ii) 6 N HCL

• Add 530.3 ml concentrated HCl in 400 ml distilled water and make the volume to one litre after cooling the solution.

iii) Pepsin powder (1:3000)

Procedure

1. Take 0.50 g finely ground (particle size<1mm) sample in 100 ml conical flask / tube.
2. Add 40 ml CO
3. Pass CO
4. Incubate the flask / tube at 39
5. After 48 h of incubation, add 2 ml 6 N HCl and 0.1 g pepsin powder.
6. Incubate the tubes for another 24 h.
7. Filter the contents through filter paper (No. 54) or sintered crucible (G1).
8. Dry the residue at 100
9. Run parallel blank with phosphate-carbonate buffer and rumen liquor without feed sample.
10. 2 saturated phosphate-carbonate buffer and 10 ml strained rumen liquor.2 through the contents for 10 seconds and put a stopper (cork fitted with Bunsen valve) on the flask / tube immediately. oC with periodic shaking. oC overnight and weigh.

Calculation

DM disappearance = Wt. of sample – (Wt. of residue of test – Wt. of residue of blank)

                                               DM disappearance

DM digestibility (%) = --------------------------------- x 100

                                           Wt. of sample (DM basis)

Precautions

• Collection of rumen liquor a. Feed normal diet twice daily for about seven days to the donor animal.
  • Draw homogenous rumen liquor samples from different parts of rumen.
  • Filter rumen liquor through four layers of muslin cloth.
  • Carry rumen liquor to the laboratory in an insulated jug with temperature maintained at 39
• Rumen liquor should be collected three hours of post feeding.
• The animal should not be given water between one and three hours post feeding.

0C. 3          9.80 g 2HPO₄2 H₂O          7.00g₄.2H₂O          0.12 g²          0.04 g The in vitro digestibility of feeds for ruminants can be measured by fermenting them with rumen liquor and then treating with pepsin. This is also known as two stage in vitro method. During the first stage, finely ground sample of feed is incubated for 48 h with buffered rumen liquor in a tube under anaerobic conditions. In the second stage, the microbial activities are stopped by acidifying with HCl to pH 2.0 and then digested by incubating with pepsin for another 24 h., the insoluble residue is filtered off, dried and ignited, and its organic matter is subtracted from the feed to obtain digestible organic matte