Plant and Animal Nutrient Sources for Dry Pet Food

In this latest installment of the series on ingredients for making pet food, we will analyze the sources of nutrients for dry foods, which represent 96% of sales volume in Latin America and therefore a very important source of commercial transactions. Although most of these ingredients are used in food for all types of animals, it is very important to define an exclusive specification for pets that considers one of the most important parameters of our industry to achieve success: the sensory properties, specifically the palatability of the individual ingredients.

Ingredients used in all market segments

Corn (Zea mays) 1

Corn is the most used raw material in the pet food industry, it represents in some products up to 60% of its formulation and in regions such as Latin America it can represent 50% of the volume of purchases of ingredients in companies. In each ingredient we will focus on a technical aspect of quality, in the case of corn it will be the reception controls of the ingredient, that is, the acceptance criteria. Since it represents 50% of the purchase volume, it is a very important ingredient from every point of view.

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There are different genetic varieties of corn in the world, the most suitable for the manufacture of pet food is yellow corn and in terms of commercial classifications it must comply with USDA grade 2, as a minimum.

Of all the quality requirements for yellow corn, the most important to control is the mycotoxin content, particularly aflatoxins, since pets are particularly sensitive to these contaminants. A thorough review of toxins from fungi is outside the limits of this work, we suggest going deeper into Munkvold (2).

Before reviewing the most appropriate parameters to receive corn in a production plant, we will clarify that it is essential to have a very efficient sampling system to obtain representative portions of the several tons of corn that are received in a company monthly.

The most common specification for corn used in pet food is as follows:

Corn is one of the main sources of energy in food, the energy comes from starches, amylose and amylopectin, which are also the main components to be modified by gelatinization during the extrusion process. Therefore, it is an ingredient that has nutritional and functional properties (functionality is the technological behavior in the production process). This is why the quality of the corn has an impact on the food format, the behavior of the extrusion system, the digestibility and the density of the final product. Reasons why monitoring of this ingredient is of utmost importance.

Rice (Oryza sativa)

Rice is the third most used cereal worldwide in the manufacture of pet food, in some regions it is used even more than corn since the price and availability are better. Rice has a better digestibility (3) level than corn and its starches are also more functional in commercial extrusion systems. These two reasons place it as a cereal of choice in the formulation of premium diets that do not have the restriction of being grain-free.

The incidence of contaminants in rice is comparatively lower than in corn, however, a careful mycotoxin analysis is essential before enabling its use in an industrial formulation. The quality parameters usually required for rice used in pet diets are:

Description: brewing broken rice, quarter grain or higher. Without added additives. As seen, whole grain is not used in pets but broken grain, the fundamental reason is the cost of the whole grain and the fact of avoiding competition with human food. Since the broken grain is more likely to deteriorate it is very important to be strict with the quality control of this ingredient and with the storage conditions.

 Animal fats (Chicken oil)

Chicken oil, beef tallow, pork tallow and fish oils are generally used as animal fats in the production of pet food. Samples that the first three fulfill functions of providing energy and flavor, fish oil is fundamentally a source of unsaturated fatty acids omega 3 and 6. In this article for reasons of space we will only analyze chicken oil, being the requirements applied to this ingredient applicable to other fats from different species.

All animal by-products come from the remnants of the meat-processing industry for humans, for economic and environmental reasons all parts of the animals that are not consumed must be transformed into usable and non-polluting by-products. Thus, for example, from the poultry industry, after the chickens are processed, there are remaining feathers, blood, viscera and some unconsumed parts. The feathers are hydrolyzed and converted into feather meal, the blood is spray dried and is a source of protein for the animal feed industry, and the viscera are cooked in digesters with steam and pressure, generating two products, a high-content meal. protein of great digestibility and palatability, chicken gut meal, which we will review later, and chicken oil.

Given that the production processes of these animal ingredients are not completely standardized, it is very important to clearly define what you want to buy, for example in the case of chicken oil, a concise definition can be the following:

'Chicken oil resulting from the first filtration of the digestion process of fresh chicken entrails. Product obtained from the fusion of avian tissues from the commercial slaughter process in authorized cold stores. It consists essentially of glycidic fatty acid esters and does not contain free fatty acids or other matters obtained from fat. The raw raw material must be stabilized with an antioxidant during cooking to avoid the development of peroxides. Industrial chicken oil must be stabilized with BHT, BHA, tocopherols (300 ppm). The raw material may not be more than 12 hours at room temperature before its treatment. "

As can be seen, the definition of the ingredient involves the parts of the animal that take part in the process, the type of manufacturing process, and the conditions of the raw material. Another important piece of information to be provided to suppliers in the product specification is the level and strategy of anti-oxidation of the fat, which is essential for the ingredient to be suitable for food manufacturing (4).

From a physicochemical and organoleptic point of view, chicken oil must meet these requirements at least:

The chicken oil is added to the outside of the food in an operation known as application, the objective is to add energy, but also palatability and shine to give a more attractive appearance to the final kibbles. Since the application operation proceeds at low temperatures, if the oil is microbiologically contaminated, so will the final product, for which the microbiological control in the reception and storage of this ingredient must be strict.

Ingredients used preferably in food of the economic segment

Wheat bran

The bran is a residue of the milling of the wheat grain, made up of the husk (pericarp) and mixed with the surface part of the albumen or germ (endosperm). In general it is presented as fine powder, flakes or pellets. It is a product with drawbacks and benefits, the greatest benefit is that it contains a high percentage of proteins at a very affordable price, the major drawback is that it can have high concentrations of vomitoxins.

In cheap foods it is a fundamental ingredient due to its low level. The quality parameters usually specified are the following:

Soybean flour

Soy flour is a very complete and inexpensive source of vegetable protein, it is obtained from the processing of soybeans. The process consists of the extraction of the oil and subsequent cooling of the flour that remains after the extraction. Although the protein is of good nutritional quality, due to the heat of the extraction process it loses all its functionality, this important quality of the ingredients is preserved by the soy isolates, which we will review later.

The most common parameters are:

Soy flour is generally the second ingredient in purchase volume after corn in a typical Latin American plant. It is therefore another very important ingredient for the industry (5).

Ingredients used preferably in standard segment foods

Bovine Meat and Bone Meal (6)

Meat meal is the main source of animal protein used in pet food, it is a by-product of bovine slaughter, fresh viscera and other by-products of beef slaughter are processed in digesters at high temperature and pressure immediately. such a way to avoid the development of biogenic amines such as histidine. It cannot include blood, hair, horns, hooves, and leather. It must not contain additives or adulterants, toxic or harmful materials and any part of another animal that is not cattle. When the cooking product is pressed, the bovine tallow and meat and bone meal are isolated.

Typically it has these physicochemical parameters:

Organoleptic parameters:

Wheat (7)

Wheat is the second most used cereal in the world to make pet food, both rice and wheat are related to standard or premium segment foods. In addition to being a source of energy through its high starch content, it also provides good quality protein and fiber. The most common specification in the industry is USDA grade 3 or higher.

Organoleptic requirements:

The most dangerous contaminant in wheat is DON vomitoxin, from the fusarium fungus that grows and produces mycotoxins under specific conditions of humidity and temperature, generally related to harvests in rainy seasons and storage of very humid wheat in hot climates, when this situation occurs, it is important to tighten the controls of this parameter.

Ingredients used preferably in premium segment foods

Chicken by-product meal (8)

Chicken by-product meal is one of the most digestible animal protein sources available on the global ingredient market. On the other hand, in recent decades a major effort has been made to standardize this ingredient by poultry companies and the animal feed industry, generating a high added value ingredient with very specific quality controls and an industrial standard, commonly used in various countries around the world. The description of the ingredient is the same as for chicken oil, come from the same production process and are separated during the pressing operation, followed by the typical parameters of a chicken meal:

Organoleptic parameters:

This has been a non-exhaustive review of ingredients used in the pet food industry, there are hundreds of materials that could not be analyzed for reasons of space and priority, we nevertheless believe that we have covered the most relevant ones and make clear the bases of the many facets that make up what is considered a suitable ingredient for making pet food.

For any further questions, do not hesitate to contact the author.

1) Parera, Carlos. Producción de maíz dulce / Carlos Parera. - 1a ed . - Ciudad Autónoma de Buenos Aires: Ediciones INTA, 2017.

2) Mycotoxins in corn: occurrence, impacts, and management. GP Munkvold, S Arias, I Taschl, C Gruber-Dorninger - Corn, 2019 – Elsevier.

3) Riitta Kempe, Markku Saastamoinen, Seppo Hyyppä. Composition, digestibility and nutritive value of cereals for dogs. Agricultural and Food Science · September 2004.

4) National Renderers Association. 2003. A Buyer's Guide to Rendered Products, 15-16.

5) http://www.fundacionfedna.org/ingredientes_para_piensos/harina-de-soja-47-pb, consulted 15/09/2020.

6) For more information see http://www.senasa.gob.ar/sites/default/files/ARBOL_SENASA/INFORMACION/NORMATIVA/4238/capitulo_xxiv.pdf

7) Kloster, Andrés. Utilización de trigo en alimentación animal. 2015. INTA Marcos Juárez.

8) Hertrampf J.W., Piedad-Pascual F. (2000) Poultry By-Product Meal. In: Handbook on Ingredients for Aquaculture Feeds. Springer, Dordrecht.

By: Juan Manuel Peralta