SÃO PAOLO and GRUGLIASCO, ITALY — With the current boosted interest in environmental sustainability in pet food, a new study has examined the extrusion parameters, nutrient digestibility, fecal characteristics, palatability, and insulinemic and glycaemic curves of a complete-and-balanced diet for dogs in which the main carbohydrate source was a red lentil pasta byproduct (LP). 

The study, titled “Lentils pasta byproduct in a complete extruded diet for dogs and its effect on extrusion, digestibility and carbohydrate metabolism,” was conducted at the Universidade Estadual Paulista (UNESP) in São Paulo, Brazil by Ticiane Giselle Bitencourt Freire, Stephanie de Souza Theodoro, Juliana Lopes Frias and Aulus Cavalieri Carciofi from the Department of Veterinary Clinic and Surgery at the UNESP, as well as Liviana Prola, Ugo Ala and Livio Penazzi from the Department of Veterinary Services at the University of Turin in Italy. It was published in Frontiers in Veterinary Science.

The production of protein sources requires a substantial amount of land and water, making them ingredients with a high ecological impact. However, protein as a macronutrient has become highly important for pet owners when choosing food for their pets. 

According to the researchers, using alternative raw materials, such as byproducts from the food industry, offers a way of improving nutrient provision and pet food sustainability in terms of both economics and the environment. With the pet food industry constantly growing, new, sustainable sources of protein, such as LP, are being sought out to meet both the market’s demand and the expectations of pet owners, according to the researchers. 

 “Research interest in the use of pulses in the pet food industry is growing fast, but data on the extrusion processing and kibble formation of dog food containing this ingredient is scarce, and no studies have been performed to date with respect to lentils,” the researchers wrote.

The study consisted of formulating five dry extruded experimental diets for dogs using various levels of LP used. All the diets were formulated to supply the nutritional requirements of adult dogs according to guidelines from the European Pet Food Industry Federation (FEDIAF). The ingredients were ground at the Sistema Tigre de Mistura e Moagem in São Paulo and extrusion processing was carried out on a single-screw extruder at Manzoni Industrial Ltda in Campinas, Brazil. 

The experimental diets included:

• A basal diet made of rice and a poultry byproduct
• Three diets where LP substituted rice at 33%, 66% or 100% inclusion levels
• A diet formulated with 70% of the basal diet plus 30% LP to evaluate LP digestibility

Researchers conducted the study using 40 adult, clinically healthy, beagle dogs (19 males and 21 females) that were randomly divided into five groups in which each group received a different experimental diet. The researchers then analyzed nutrient digestibility, fecal fermentation end-products, glycaemic and insulinemic curves, biogenic amines and nitrogen balance evaluation in the dogs.

The researchers found that inclusion of LP did not affect the intake levels of dry matter, organic matter or acid-hydrolyzed fat. The results also indicated that the ingredient has high nutrient digestibility when the replacement of rice was only partial, such as in the 33% and 66% diets. It also increased the level of fermentation byproducts in the feces, indicating the potential benefits of LP on intestinal health due to its high content of fermentable fiber. Finally, the study found that palatability was enhanced in the formulation containing the red lentil pasta byproduct, further supporting its use as a suitable ingredient in dog food.

The substitution of rice with LP influenced extrusion processing, with higher resistance to mass flow and mechanical energy application, resulting in kibbles that were less expanded and harder. The researchers explained that these effects will need to be considered when establishing the ideal processing conditions for a LP-based dog food.

The researchers wrote, “This trial reveals how a byproduct discarded from the human-grade food chain retains both its nutritional and organoleptic properties.”

Read the full study here.

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