Environmental impact of diets for dogs and cats

Abstract

Food production is responsible for almost one-quarter of the environmental impact and, therefore, its importance regarding sustainability should not be overlooked. The companion animal population is increasing, and an important part of pet food is composed of ingredients that have a high environmental impact. This study aimed to evaluate the impact of dry, wet, and homemade pet diets on greenhouse gas emission, land use, acidifying emission, eutrophying emissions, freshwater withdrawals, and stress-weighted water use. The wet diets were responsible for the highest impact, and dry diets were the type of diet that least impacted the environment, with a positive correlation between the metabolizable energy provided by animal ingredients and the environmental impact. It is necessary to consider the environmental impact of pet food since it is significant, and the population of pets tends to increase.

Figure 1

Boxplots of the distribution of percentages of crude protein, crude fat, and amount of metabolizable energy provided by either animal or vegetable origin for each type of diet. Diet category: Cc homemade diets, Cs website homemade diets, S dry diets, and U wet diets. Plots of the same variable that have different letters differed (p < 0.05) according to the multiple comparison test between groups.

Figure 2

Boxplots of the estimated environmental impact per 1000 kcal of diets for dogs according to the type of diet for the variables carbon dioxide equivalent emission, land use, acidifying emission, eutrophying emission, freshwater withdrawal, and stress-weighted water use. Plots of the same variable that have different letters differed (p < 0.05) according to the multiple comparison test between groups. Diet category: Cc homemade diets, Cs website homemade diets, S dry diets, and U wet diets. Plots of the same variable that have different letters differed (p < 0.05) according to the multiple comparison test between groups.

Figure 3

Boxplots of the estimated environmental impact per 1000 kcal of diets for dogs according to the type of diet for the variables carbon dioxide equivalent emission, land use, acidifying emission, eutrophying emission, freshwater withdrawal, and stress-weighted water use. Plots of the same variable that have different letters differed (p < 0.05) according to the multiple comparison test between groups. Diet category: Cc homemade diets, Cs website homemade diets, S dry diets, and U wet diets. Plots of the same variable that have different letters differed (p < 0.05) according to the multiple comparison test between groups.

Figure 4

Principal component analysis (PCA) of first principal component (PC1) versus second principal component (PC2) of diets for dogs. ENN  nitrogen-free extract, PBv protein from vegetable sources, Emv metabolizable energy from vegetable sources, Eev fat from vegetable sources, CO2eq carbon dioxide equivalent, area land use, PO4eq phosphate equivalent, SW stress-weighted water usage, SO2eq sulphur oxide equivalent, UA freshwater withdrawals, PB protein content, EE fat content, Ema metabolizable energy from animal sources, Pba protein from animal sources, Eea fat from animal sources.

Figure 5

Biplot of standardized first (PC1) and second principal components (PC2) with observations of diets for dogs. Cc homemade diets, Cs website homemade diets, S dry diets, U wet diets, ENN nitrogen-free extract, PBv protein from vegetable sources, Emv metabolizable energy from vegetable sources, Eev fat from vegetable sources, CO2eq carbon dioxide equivalent, area land use, PO4eq phosphate equivalent, SW stress-weighted water usage, SO2eq sulphur oxide equivalent, UA freshwater withdrawals, PB protein content, EE fat content, Ema metabolizable energy from animal sources, Pba protein from animal sources, Eea fat from animal sources.

Figure 6

Principal component analysis (PCA) of first principal component (PC1) versus second principal component (PC2) of diets for cats. ENN nitrogen-free extract, PBv protein from vegetable origin, Emv metabolizable energy from vegetable origin, Eev fat from vegetable origin, CO2eq carbon dioxide equivalent, area land use, PO4eq phosphate equivalent, SW stress-weighted water usage, SO2eq sulphur oxide equivalent, UA freshwater withdrawals, PB protein content, EE fat content, Ema metabolizable energy from animal sources, Pba protein from animal sources, Eea fat from animal sources.

Figure 7

Biplot of standardized first (PC1) and second principal components (PC2) with observations of diets for cats. Cc homemade diets, Cs website homemade diets, S dry diets, U wet diets, ENN nitrogen-free extract, PBv protein from vegetable sources, Emv metabolizable energy from vegetable sources, Eev  fat from vegetable sources, CO2eq carbon dioxide equivalent, area land use, PO4eq phosphate equivalent, SW stress-weighted water usage, SO2eq sulphur oxide equivalent, UA freshwater withdrawals, PB protein content, EE fat content, Ema metabolizable energy from animal sources, Pba protein from animal sources, Eea fat from animal sources.