Multi layer extrusion

1. A process for forming a pet chew comprising:

providing a first extruder operable with a first extruder die providing a first extruder die profile shape, a second extruder operable with a second extruder die providing a second extruder die profile shape and a third extruder operable with a third extruder die having a third extruder die profile shape;

providing a first composition containing a nutritional additive to said first extruder and a second composition to said second extruder and a third composition containing a nutritional additive to said third extruder;

extrusion processing said first composition through said first extruder and said first extruder die to form a first extrudate having a first extrudate profile shape;

extrusion processing said second composition through said second extruder and said second extruder die to form a second extrudate having a second extrudate profile shape;

extrusion processing said third composition through said third extruder and said third extruder die to form a third extrudate having a third extrudate profile shape;

joining said first extrudate, said second extrudate and said third extrudate to one another with a combining die located downstream of the first extruder die, the second extruder die and the third extruder die;

wherein said first extruder is operating at a selected barrel temperature (BT 1 ), including a selected residence time for said first composition (RT 1 ) and a selected shear rate (γ 1 );

wherein said second extruder is operating at a selected barrel temperature (BT 2 ), a selected residence time for said second composition (RT 2 ) and a selected shear rate (γ 2 );

wherein said third extruder is operating at a selected barrel temperature (BT 3 ), a selected residence time for said third composition (RT 3 ) and a selected shear rate (γ 3 );

wherein at least one of the following conditions is present:

BT 1 <BT 2

RT 1 <RT 2

γ 1 <γ 2 ; and

wherein at least one of the following conditions is present:

BT 3 <BT 2

RT 3 <RT 2

γ 3 <γ 2 ; and

wherein said first and third extrudates each provide a portion of an outer layer and said second extrudate provides a core, and wherein the first and third extrudates are each directly bonded to the second extrudate forming the core and completely surround the second extrudate forming the core;

wherein said nutritional additive of said first composition is a thermally degradable and/or shear degradable nutrient additive;

wherein said nutritional additive of said first composition is not present in the second composition; and

wherein said nutritional additive of said first composition comprises a vitamin or mineral or herb, wherein 75% or more by weight of said nutritional additive in said composition remains non-degraded after processing in said first extruder.

2. The process of claim 1 wherein at least two of the following conditions are present: BT 1 <BT 2 ; RT 1 <RT 2 ; γ 1 <γ 2 .

3. The process of claim 1 wherein the following conditions are present: BT 1 <BT 2 ; RT 1 <RT 2 ; γ 1 <γ 2 .

4. The process of claim 1 wherein at least two of the following conditions are present: BT 3 <BT 2 ; RT 3 <RT 2 ; γ 3 <γ 2 .

5. The process of claim 1 wherein the following conditions are present BT 3 <BT 2 ; RT 3 <RT 2 ; γ 3 <γ 2 .

6. The process of claim 1 wherein said first and second compositions comprise one of a starch, a gluten, a carbohydrate, rawhide or meat.

7. The process of claim 1 wherein said first and second compositions comprise raw starch.

8. A process for forming a pet chew comprising:

providing a first extruder operable with a first extruder die providing a first extruder die profile shape, a second extruder operable with a second extruder die providing a second extruder die profile shape and a third extruder operable with a third extruder die having a third extruder die profile shape;

providing a first composition containing a nutritional additive to said first extruder and a second composition to said second extruder and a third composition containing a nutritional additive to said third extruder;

extrusion processing said first composition through said first extruder and said first extruder die to form a first extrudate having a first extrudate profile shape;

extrusion processing said second composition through said second extruder and said second extruder die to form a second extrudate having a second extrudate profile shape;

extrusion processing said third composition through said third extruder and said third extruder die to form a third extrudate having a third extrudate profile shape;

joining said first extrudate, said second extrudate and said third extrudate to one another with a combining die located downstream of the first extruder die, the second extruder die and the third extruder die;

wherein said first extruder is operating at a selected barrel temperature (BT 1 ), including a selected residence time for said first composition (RT 1 ) and a selected shear rate (γ 1 );

wherein said second extruder is operating at a selected barrel temperature (BT 2 ), a selected residence time for said second composition (RT 2 ) and a selected shear rate (γ 2 );

wherein said third extruder is operating at a selected barrel temperature (BT 3 ), a selected residence time for said third composition (RT 3 ) and a selected shear rate (γ 3 );

wherein the following conditions are present:

BT 1 <BT 2

RT 1 <RT 2

γ 1 <γ 2 ; and

wherein the following conditions are present:

BT 3 <BT 2

RT 3 <RT 2

γ 3 <γ 2 ; and

wherein said first and third extrudates each provide a portion of an outer layer and said second extrudate provides a core, and wherein the first and third extrudates are each directly bonded to the second extrudate forming the core and completely surround the second extrudate forming the core;

wherein said nutritional additive of said first composition is a thermally degradable and/or shear degradable nutrient additive;

wherein said nutritional additive of said first composition is not present in the second composition; and

wherein said nutritional additive of said first and third composition comprises a vitamin or mineral or herb, wherein 75% or more by weight of said nutritional additive in said first and third composition remains non-degraded after processing in said first and third extruders.

9. The process of claim 8 wherein said first, second and third compositions comprise one of a starch, a gluten, a carbohydrate, rawhide or meat.

10. The process of claim 8 wherein said first, second and third compositions comprise raw starch.