GB2245475A

GB2245475A - Improvements in the treatment of animal feeds

Info

Publication number: GB2245475A
Application number: GB9014890A
Authority: GB
Inventors: Richard Hewitt
Original assignee: SPECIAL MILLING Ltd
Current assignee: SPECIAL MILLING Ltd
Priority date: 1990-07-05
Filing date: 1990-07-05
Publication date: 1992-01-08
Anticipated expiration: 2010-07-05
Also published as: GB9014890D0; GB2245475B

Abstract

The invention is concerned with the treatment of animal feeds to destroy Salmonella. It employs alkaline reagents such as ammonia and ammonia hydroxide as the bactericidal agent.

Description

DESCRIPTION IMPROVEMENTS IN THE TREATMENT OF ANIMAL FEEDS The present invention relates to the treatment of animal feeds, and more particularly to the treatment of animal feeds of animal origin.

Government regulations now require animal feeds proteins, of animal origin, to be treated to destroy salmonella.

In practice this can be done in one of three ways.

Animal feed proteins can be irradiated. This is a slow and expensive process and is not therefore commercially viable.

Animal feed proteins can be heated. This method is slow, results in the denaturing of the proteins, is costly and provides no after protection.

For the above reasons, chemical treatments are prefered.

The chosen method is an acid treatment. A mixture of about 3% formic and propionic acids are added to the animal feed in a mixing screw.

Whilst proving efficient with some animal feeds, the method suffers from several drawbacks.

Firstly, the acids react with the calcium carbonate content of any bone material present. This inactivates the acids, and consequently large volumes are required. This makes the process expensive and where a large percentage of the treated product is incorporated into the feed results in a product which is generally unpalatable if they are not mixed with other feedstuffs. For example, fish foods contain 4050% fishmeal and if acid treated fishmeal is used, the fishfood is unpalatable. By contrast a poultry feed which may contain only 5% fishmeal is palatable since in these proportions the taste of the acid is masked and the feed is acceptable to the birds.

Also, since acids do not easily permeate fatty material, where the feed to be treated is rich in fat, it is possible for any salmonella present in the feeds to be protected by the natural fat content of the animal proteins.

Finally, the acids are corrosive and potentially damaging to machinery and dangerous to the operaters. The acids may also react with the metal of the mixing screw and ferrous and ferric salts may be absorbed into the feeds.

It is one object of the invention to find a treatment which can improve upon the discussed art.

In particular it has been an aim to find a treatment which will produce salmonella free animal feed proteins of animal origin such as, for example, fishmeal and fishmeal blends, meat and bone meal, meat meal, bone meal, blood meal, feathermeal, hide meal and poultry offal meals, which treated feed is palatable to substantially all classes of livestock including fish.

According to one aspect of the present invention, there is provided a method of treating animal feeds of animal origin, to destroy salmonella characterised in that said method employs an alkaline treatment.

Preferably, the alkaline treatment employs gaseous ammonia, ammonium hydroxide and/or ammonium carbonate.

In one embodiment the alkaline treatment employs a volatile alkaline reagent.

By moving away from acid treatments towards alkaline reagents the problem of the acid reacting with any calcium carbonate, is alleviated and consequently the dilution effect which occurs in the neutralising of the acid within the feed is avoided.

The employment of a volatile agent further means that no residual agent is left after treatment and consequently the palatability of the resulting feed is not affected.

Furthermore, by using a volatile agent permeation is increased and thus the agent can act more efficiently.

According to a further aspect of the invention, there is provided a method of preserving an animal feed of animal origin against attack by salmonella which method comprises adding an effective amount of ammonium carbonate to said feed.

The addition of ammonium carbonate increases the degree of after protection by allowing the slow release of ammonium during any subsequent storage operation. The evolution of harmless carbon dioxide, further aids dispersion of the ammonia through the feed.

The various aspects of the invention will now be described, by way of example only, with reference to the following examples.

EXAMPLE 1 4000 Kg of fishmeal, was placed in a closed mixing vessel and 40 kilograms of 0.880 Ammonia solution was added. The feed was subjected to a high shearing action by means of a recirculating spiral conveyor 300 mms diameter driven by a 30 HP electric motor for 6 minutes so that the solution could fully permeate the feed.

The resulting feed was tested and found to be free from salmonella.

By providing intimate mixing of ammonia and feed in a closed mixer, the ammonia is able to penetrate any fatty material coating the salmonella cell walls. Thus it can penetrate and kill the bacteria, thereby selectively sterilizing the feed.

This is an improvement on acid based systems because acid cannot permeate fatty material.

Furthermore, since the ammonia is volatile it can, after the treatment is complete escape from the feed, leaving the treated feed free from chemical contamination. This ensures there can be no side effects due to the retention of preservative in the feed.

As well as selectively sterilizing the feed, any ammonia which is not allowed to escape will also act as a preserving agent. This feature can be enhanced by the addition of, for example, ammonium carbonate to the feed.

EXAMPLE 2 Bloodmeal, a soluble protein was placed in a closed container and ammonia gas was pumped into the mixer which was stired. The ammonia gas was kept in contact with the mix for a period sufficient to cause sterilization. Being non-aqueous the active agent avoids re-hydration of the blood meal and the need for re-drying after treatment.

Claims

1. A method of treating animal feeds of animal origin to destroy Salmonella characterised in that said method employs an alkaline treatment.

2. A method as claimed in claim 1, in which the alkaline treatment employs gaseous ammonia.

3. A method as claimed in claim 1, in which the alkaline treatment employs ammonium hydroxide.

4. A method as claimed in any of the preceding claims, in which the alkaline treatment employs ammonium carbonate.

5. A method as claimed in any of the preceding claims, wherein the animal feed of animal origin is selected from the group comprising fishmeal and fishmeal blends, meat and bone meal, meat meal, bonemeal, bloodmeal, feathermeal, hide meal and poultry offal meal.

6. A method as claimed in any of the preceding claims, which further comprises subjecting the feed to a high shear action.

7. A method of treating animal feeds of animal origin to destroy Salmonella, characterised in that said method employs a volatile alkaline reagent.

8. A method as claimed in claim 7, wherein the volatile alkaline reagent is ammonia gas.

9. A method as claimed in claim 8, wherein the animal feed of animal origin is bloodmeal.

10. A method as claimed in any of claims 7, 8 or 9, which further comprises subjecting the feed to stirring.

11. A method as claimed in any of claims 8, 9 or 10, which further comprises the addition of ammonium carbonate.

12. A method of preserving animal feed of animal origin against attack by Salmonella which method comprises adding an effective amount of ammonium carbonate to said feed.