Dogs prefer Meat over Carbohydrates, given the choice!

Published article:
Macronutrient intake of dogs, self-selecting diets varying in composition offered ad lib.

Where and when:

Massey University Canine Nutrition Unit.
Palmerston North, New Zealand.
Published July 2017 Journal of Psychology and Animal Nutrition.
Authors: M.T. Roberts, E.N. Bermingham, N.J. Cave, W. Young, C.M. McKenzie, and D.G. Thomas.

Question in research:
Do dogs prefer Meat (and Fat) diets, over carbohydrates?

Would dogs select a diet consisting of more than 30% of total energy from protein?

Study participants:

15 Harrier Hound dogs (five male and ten female), four of the male dogs were neutered and three of the female dogs were neutered, the rest of the dogs were entire.
All of the dogs had a physical examination and were deemed healthy.
Mean age of the dogs was 7.68 yrs.

The dogs were housed in pairs in 10m x 10m (100m2) outdoor pens or in groups of 4 in grass paddocks measuring 700m2 for 8 hours of the day. Then at night the dogs were housed in pairs indoors with a water supply and bedding. 

What they did:

10-day self-selection diet study with an added 5-day transitional period.
Three diets consisting of the same ingredients at different inclusion levels were formulated to make a high protein diet (HP), a high fibre diet (HF), and a high carbohydrate diet (HC).

The ingredients used were maize (for the carbohydrate), lamb loin fat, green tripe and venison (for the meat types) that had been deboned. 

The levels of protein, fat, ash and moisture and NFE (nitrogen free extract) were analysed for each diet. 

A 5-day transition period was done traditionally by increasing the mixtures of the test diets by 20% daily, whilst concurrently decreasing their existing commercial dry diet by 20% daily. The 10-day experimental diet phase then started.

The weight of the dogs were recorded on day 1, day 5 and day 10, this was to asses the self-selected macronutrient consumption. 

The food was placed into three large bowls, each containing 250% of the daily energy requirement of the HF, HC, HP diets at both 8am and 2pm. All three of the diets were offered at the same time (for the dogs to choose).
The positions of the bowls were changed regularly to prevent positional bias.

Feeding dynamics were observed both by an observer and by a video camera to record which diet was approached first and which were avoided completely. 

The dogs were offered the diets until they had completely lost interest. 

Results 

The bodyweight of the dogs increased significantly over the 10-day period with an average bodyweight of 25.9kg on day 1, and 27.5 on day 10. (not surprising if they ate that bit more than they needed)

Observational data

High protein diet was first approached by 47% of the dogs and first consumed by 64% of the dogs.
High carbohydrate diet was first approached by 24% of the dogs and first consumes by 4% of the dogs.
High fat diet was first approached by 29% of the dogs and first consumed by 30% of the dogs.

Macronutrient consumption:

Protein intake: 29.4% day 1 – 44% day 10

Fat intake: 68% day 1 – 52% day 10

Carbohydrate intake: No significant change 2.5% day 1 – 4.4% day 10

Conclusion

The study shows that when dogs are given the choice to self-select from diets that vary in macronutrient composition, they will choose to consume at least 30% of their energy from protein.
Clearly Protein means more to dogs, given the choice.
The question isn’t simply can they digest it, its are the instinctively biologically designed to self-select it.

Blog collaboration, Hannah Sussenbach and Caroline Griffith