|‘surprise’ meat finding by calcutta TEAM
|A cartoon by research scholar Anandarup Bhadra
New Delhi, Oct. 20: A study of street dogs in Calcutta has challenged a long-standing assumption that the food preferences of dogs, whether young or old, are guided by an inborn rule of the thumb: if something smells like meat, eat it.
The study by scientists at the Indian Institute of Science, Education and Research (IISER), Calcutta, has suggested that puppies lack the ability to recognise meat as a priority food and need to learn this, possibly from their mothers.
“The lack of preference for meat among pups was a surprise,” said Anindita Bhadra, a faculty member and fellow at the IISER, who supervised the study.
The findings have been accepted for publication by the Journal of Ethology.
The researchers said their study suggests that the development of the preference for meat in dogs, the descendants of carnivorous wolves, occurs either through repeated exposures to meat or learning or a combination of both processes.
In the study, Anandarup Bhadra, a scholar at the IISER, walked along the streets of Calcutta and offered 60 pups and 60 adult dogs in separate encounters what the scientists call a one-time multiple option choice test — three food options each equally accessible.
He offered each dog three types of almond-sized food pellets — one loaded with meat protein, another containing degraded protein, and the third had synthetic non-animal protein, but visually identical — and documented their preferences.
|Anandarup tries the multiple option food test on a street dog; (right) Anindita Bhadra with a street dog in Calcutta
The adult dogs displayed a clear choice of preference — they preferred the meat pellets and avoided food containing degraded or synthetic protein. But the pups did not discriminate between the pellets.
While the adult dogs seemed to use the rule-of-thumb — if something smells like meat, eat it — the pups appeared to grab the first food option they spotted, consuming it quickly, without inspecting the other food options available.
“The pups follow a sniff-and-snatch strategy,” said Bhadra. This may benefit growing pups that have high dietary energy needs. Any attempts to discriminate between food options might lower food intake during their critical phase of growth.
The researchers believe the rule-of-thumb is acquired over time. When pups are five to six weeks of age, their mothers regurgitate solid food, rich in protein, that the scientists say allows pups to prepare themselves to consume solid food.
A study led by Swedish scientists earlier this year had suggested that the ability to digest starch-based carbohydrates was a key step in the emergence of domesticated dogs from wild wolves, their carnivorous ancestors.
The IISER scientists point out that street dogs in India survive as scavengers around human settlements and have adapted to a diet rich in carbohydrates such as biscuits, bread, rice or fish bones.
While street dogs have adapted to scavenging and a carbohydrate-dominated diet, the IISER researchers speculate that the rule-of-thumb helps dogs consume as much protein as they can when they can find it.
A scientist in an anonymous review of the IISER paper said it “adds to the scientific understanding of the feeding behaviour of dogs” and “provides insight into how domestication has changed the feral dogs’ foraging habits”.
But the process through which pups pick up the preference for meat remains unclear. Bhadra said: “This raises the possibility that pups learn passively through observation and social learning or are actively taught by their mothers.”