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In vitro ileal digestibility of dry matter (DM), N and

               organic matter (OM) in pigs.

Principle

The in vitro estimation of ileal digestibility permits the evaluation of the quality of feeds, specially N and amino acids for pigs. It has been well established the straight correlation which does exits between in vitro ileal and in vitro (pepsin/ pancreatin), and in turn, the interdependence between in vitro ileal N digestibility and performance traits of economic importance in pigs.

The methods herein described is that proposed by Dierick et al (1985) fully developed in tropical non conventional feeds at the swine Research Institute at Havana by the research team of Ly (see for example, Dominguez et al 1996).

Procedure

1/ Weight an amount of dry and ground sample containing 150 mg of protein (N x 6.25) and

  put it into a 100 ml erlenmeyer flask. Add 20 ml of a pepsin solution (1mg enzyme/`mlHCL 0.075 N) plus a drop of timerosal.

  2/ Incubate the sample in a water bath at 37oC (preferably 80 strockes per minute) during 4  hours.

  3/ Neutralize until pH = 7.5 with NaOH (or KOH) 0.2N ( about 7.5 ml).

  4/ Add 20 ml of a solution of 15% pancreatin in a phosphate buffer. The phosphate buffer   can be prepare by mixing 10 of a solution of 31.50g KH2PO4.3H2O/ L and 90 ml of

another solution of 45.6g K2HPO4/ L. The solution is adjusted to pH = 7.5 and made up to a L with distilled water. Repeat the incubation in a water bath at 37oC as in 2.

  5/ Add a solution of sodium tungstate (5%) to precipitate the undigested protein.

6/ Transfer the solution quantitatively to a 120 ml centrifuging tube and centrifugue the

     sample during 10 minutes at 1250 rpm. As alternative, filter quantitatively, in a previously   weighed filter paper.

  7/ Dry to constant weight to determine the dry insoluble residue

8/ Determine the ash content in other dry insoluble residue to calculate the insoluble organic   matter.

9/ Determine the N content by the Kjeldhal procedure in another dry insoluble residue.

Calculation

                                                   OS - DR

                     % IVDDM =      --------------- x 100

                                                       OS

      Where :

                   * OS = Weight of the original sample, in dry basis

                   * DR = Weight of the dry residue

  When the in vitro digestibility of organic matter (IVDOM) or in vitro digestibility of N (IVDM) is to be estimated, calculate by the same procedure for example, the IVDN should be calculated by the following equation.

                                                 NOS -N DR

                     % IVDN =      -------------------  x 100

                                                     N OS

        Where :

                      * NOS = mg of N in the original sample

                      * NDR = mg of in the dry residue.

References

  Dierick, N, Vervaeke, I., Decuypere, J. and Henderickx, H. 1985. Protein digestion in pig measured in vitro and in vitro. In : Proc, 3^rd Int. Seminar Dig. Physiol. Pig (A. Just, H. Jogensen and J. A. Fernandez, ed.) Kobenhavn p 329 - 332.

  Dominguez, P. L., Molinet, Y. and Ly, J. 1997. Ileal and in vitro digestibility in the pig of three floating aquatic macrophytes. Livest. Res. Rural Devel. 8(4) : 37 - 44.  

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