Petfood has evolved over the years from the pets fending for themselves through being feed meat and fat scraps to supplemented table scraps prepared by pet owners. Jack Spratt concocted a biscuit like treat in the mid 1800’s and was producing by the 1890’s a product with wheat meals, vegetables and meat.After World War I Ken-L-Ration sold canned meat based for dogs with canned cat foods and dry dog food by Gains Food Co arriving in the 1930’s. Purina was not far behind as well as other players in the petfood business. The above is just a bit of history from the internet.Products & machine advancements I was recently granted the opportunity to interview Joe and Lou Wenger, generation and founders of Wenger, we discussed their interesting account of how the industry grew in the early days.

When we met, we discussed how they first fell into the extrusion cooking business and this is a good start for this review, which we will base on product advancements. But first how did such a well-known company get into this, to set the basis for how products and machine advancements went hand in hand? As mentioned by LaVon Wenger in an interview with him in the1st edition, molasses was in integral ingredient for feeds in the 1930s.

Situations had the first generation rebuilding their Feedmill and equipment improvements were added. Continuous mixers – much like the early preconditioners but for mixing hay and molasses together. With a history of pellet mill manufacturing and seeing this technology did not like elevated molasses and ground hay for pellet production.

An idea of a screw, short, press with a die might work with the mixer mounted above. Steam and water are eventually added and all kinds of various ingredients and numerous rials were conducted. One however, the die blinded closed except for a few holes where the product being trialed expanded and looked like nothing they had seen.

Kansas State University (KSU) reported to them this product was cooked, now known as gelatinised in the industry. At the time nobody really cooked animal feeds too extensively. One day KSU was asked about petfood products on the market and how was the texture made on some early extruded products, my suspicion is they were Purina Products. KSU reported they did not know but this company in Sabetha, Kansas, Wenger is doing something similar in texture. The cell structure we all know about.

Wenger was contacted and interest pointed to perhaps see if they could get the process under control and do it again on purpose. They succeeded in moving the process forward ever since, with the industry pushing them for what they wanted.

Further product & related equipment changes

Ok, moving on to the petfood product advancement and related equipment changes. Initially these products were called what is known as brown and round kibble. This was a basic formula of 48 percent ground corn, 18 percent each meat and bone meat, wheat mids and soybean meal.

Initially this simple petfood had to be controlled, single shafted preconditioners with the ability to add the needed steam and water for this were used with single screw barrels which grew in length over the early years for more cook and capacity. I suspect it was a critical point getting the die open area right for the flow at that time to control the expansion, but it was noted knife cutting was a major problem.

Finally, a U-joint shaft with a vari-speed motor was developed with knife designs improving and being developed for cutting. These machines were rough and tough and not with the best tolerance or screw mounting designs. Variation in petfood product in the early days of production occurred greatly.

Thus, obvious improvements over the years to get to the point 5, 7.5 and even 10TPH could be produced effectively and for extended time periods, with 15 to even 25TPH today are not unheard of. These improvements followed the new abilities seen in machine tooling to make the parts etc.

Tighter tolerance screws of all diameters, range of flight cutting abilities, main shaft designs, new part designs etc occurred in what seemed like an ever faster exponential upward curve, thus extruder barrel improvements for more predictable production. These discussions were by no means limited to Wenger, as Sprout Waldron and Anderson Extrusion were also in the game and developing their technologies as well.

All of us had the same situations, the expansion of the formula, equipment developments, the needed running conditions for thfinal product specs. As the petfood industry advanced the producers, nutritionists, veterinarians and the new to the industry had novel and new ideas in the formula and the product final specs. So, the equipment designs and operational aspects all were pushed to achieve the goals.

Efficiency & consistency were not the only drivers

The entire system from dry ingredient and liquids feeding evenly, preconditioners advanced to handle elevated liquids while not plugging the downspout feeding the extruder. This was due to improved ingredient hydration and increased cook levels. Efficiency and consistency were not the only drivers, but meat and fat addition were always pushed to new limits continuing the advancements.

New double shafted conditioners, some the same diameter others differential diameter allowed the desired meat levels and added vegetable and other non traditional ingredients were ongoing and today getting close to not needing much cereal grains in some extrusion processes for these formulas.

A continued impact on developments

Petfood appearance and formula such as extruded semi moist had an impact on developments, multiple-colored products, multiple color in each kibble, multiple shapes, mixtures of all of them including semi moist pieces. Filled pillows and a full range of extruded treats where textures are controlled as well as attractive shapes. Twin screw extrusion was introduced into petfood production and it was quickly seen that this technology can be useful in advancing some of the goals mentioned above.

We can’t cover it all in a short article but developments in the surrounding support industries also greatly assisted in advancements. These include control systems, accurate pumps, air systems, liquid piping systems and overall plant designs. We will strive to cover more of these as we progress.

The photo above shows many different petfood shapes, brown and round, multiple color same piece, square filled pillows, bacon strips, eggs, many of these products made with two individual extruders through a common die.

Processes exist for use of one extruder to do the same accomplishment as well. Technology continues to advancement driven by a highly competitive market, which will continue to advance the industry.

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Article contributed by Joe Kearns, Editor of International Petfood magazine.