Lal the chicken-eating cow

People often send me links to stories of the Indian cow that took to eating baby chickens. The story isn't at all new: it appeared in the press in March 2007, and at least one of the cow's lapses into carnivory was filmed. It's shown here (though see below). As with the epic cat fight, do NOT watch this video if you are easily disturbed or upset by scenes of animal death and suffering. I will spoil the surprise by telling you that the cute little baby chicken gets eaten alive by the big nasty cow.

The cow concerned - named Lal - lives in Chandpur, West Bengal (though: the cow in this video might not be Lal, but another one. I really don't know. Another video, showing a far whiter, adult Indian cow - is this Lal? - is here). Lots of chickens were going missing and, naturally, it was assumed that roving dogs were to blame. Lal's owners were thus a little surprised to see the cow sneak up to the chicken coop and to then grab and eat some of the chicks.


It's perhaps not as well known as it should be that many 'strict herbivores' will eat animal matter on occasion. Sometimes this behaviour is absolutely deliberate and likely motivated by a need for calcium: antler- and bone-eating is common in deer and other hoofed mammals, and the consumption of seabird chick heads, wings and legs by island-dwelling deer and sheep is well documented (Furness 1988). Red deer Cervus elaphus that eat seabirds seem to deliberately eat the bones only, and carefully avoid ingesting the flesh. White-tailed deer Odocoileus virginianus and domestic cattle Bos taurus have been shown (thanks again to remote cameras) to consume passerine and quail nestlings and/or eggs when they discover them (Pietz & Granfors 2000, Nack & Ribic 2005, Ellis-Felege et al. 2008): this behaviour is likely opportunistic, but may well be common and widespread (it's difficult to document since it mostly occurs at night and no evidence remains). White-tailed deer have also been seen eating fish, insects, small mammals and birds caught in mist nests: in the adjacent picture, a deer eats a rabbit (pic borrowed from the Deer & Deer Hunting forum). There are quite a few pics of deer eating small animals online, here's a video where a White-tailed deer eats a small passerine...

On other occasions, carnivory is accidental: cattle drinking from pools sometimes ingest huge quantities of tadpoles, for example (Beebee & Griffiths 2000).

In 1945, an elephant called Chang (kept at Zurich Zoo), killed and consumed Bertha Walt in entirety, including her clothes, shoes and handbag. I always thought that this was due to starvation, but these days I'm not so sure: Chang already had a reputation for being nasty and aggressive, and after Walt's death he attacked another elephant and killed his keeper, Hans Rietmann. We've covered some of this stuff before on Tet Zoo: there are also the many occasions where hippos have been seen to eat carcasses and even to catch, kill and eat birds, antelopes and other animals. And there are instances where elephants have exhumed and eaten human corpses (Spinage 1994).


Lal the cow's behaviour might be motivated by a mineral deficiency (though the idea that Lal was a tiger in a past life was also entertained by some villagers) [adjacent screen-capture, from video above, shows cow eating a chicken]. But, as shown by the studies cited below, bird-eating in bovids and deer may actually just be a fairly normal bit of behaviour that we're only beginning to document. I also think that individuals of herbivorous species sometimes learn 'accidentally' that they can kill and eat other animals, and then take to this habit as and when the opportunity arises. That is, because they can, not because they 'need' to. In fact, I'd go as far as saying that animals (and other organisms) likely do a lot of things simply because they can, not because their anatomy or physiology is specifically 'suited' to that activity.

One more thing: remember the Abolitionist Project? Someone should tell those guys that carnivores are not the only creatures that kill. Herbivores are often murderous bastards too, and 'pure' herbivory is apparently much rarer than we used to think.

I was hoping to get through a lot more stuff before stopping for Christmas, but workload is so heavy right now that I don't think this is gonna happen. Haven't even had time to produce a Tet Zoo-themed Christmas card... Well, I'll say happy Christmas now, best wishes for 2011!

For previous articles on carnivory and/or animal killing in herbivores, see...

Refs - -

Beebee, T. & Griffiths, R. 2000. Amphibians and Reptiles. HarperCollins, London.

Ellis-Felege, S. N., Burnam, J. S., Palmer, W. E., Sisson, D. C., Wellendorf, S. D., Thornton, R. P., Stribling, H. L. & Carroll, J. P. 2008. Cameras identify White-tailed deer depredating Northern bobwhite nests. Southeastern Naturalist 7, 562-564.

Furness, R. W. 1988. Predation on ground-nesting seabirds by island populations of red deer Cervus elaphus and sheep Ovis. Journal of Zoology 216, 565-573.

Nack, J. L. & Ribic, C. A. 2005. Apparent predation by cattle at grassland bird nests. The Wilson Bulletin 117, 56-62.

PIETZ, P., & GRANFORS, D. (2000). White-tailed Deer (Odocoileus virginianus) Predation on Grassland Songbird Nestlings The American Midland Naturalist, 144 (2) DOI: 10.1674/0003-0031(2000)144[0419:WTDOVP]2.0.CO;2

Spinage, C. A. 1994. Elephants. T & A D Poyser, London.


More like this

A white-tailed deer (Odocoileus virginianus), photographed in suburban New Jersey (close-up).(original)
White-tailed deer, Odocoileus virginianus, fawn found sleeping next to a hiking trail at Foley Mountain near Westport, Ontario. Image: Bev Wigney. Happy Holidays to everyone. I am receiving so many gorgeous pictures from you, amigos bonitos, and I am overwhelmed by the beauty of these images and…
A white-tailed deer fawn (Odocoileus virginianus), photographed in the summer of 2007.
A group of white-tailed deer (Odocoileus virginianus), photographed in suburban New Jersey.

as shown by the studies cited below, bird-eating in bovids and deer may actually just be a fairly normal bit of behaviour that we're only beginning to document

Also see Blank (2003), who lists several other examples of flesh-eating by ungulates (including a rhino that killed and ate a goose, and an oribi that killed and ate a bustard):

Blank, D.A. 2003. On the carnivorism and feces eating of Gazella dorcas Linnaeus, 1758 and other ungulates. Mammalia 67, 579-585.

Whoah!! Wasn't aware of that paper - I don't suppose you have a pdf? I know that perissodactyls will sometimes eat meat, as I've seen horses do it (albeit in a very much domestic setting: I'm talking about a horse that would eat hot dogs), but finding cases in the technical literature is quite the task.

I don't suppose you have a pdf?

No, I don't, unfortunately.

As I recall, there have been several carnivorous species in past times that are closely related to modern day herbivors (entelodonts and mesonychids spring to mind). They must've started eating meat somewhere in their evolution (if eating meat wasn't a primitive condition, of course).

By Kilian Hekhuis (not verified) on 20 Dec 2010 #permalink

I think I've also heard that occasionally some lagomorphs eat meat. At least, arctic hare are known to scavenge off of musk ox carcasses.

As an aside, Although I know you avoid doing Dinosaur articles given there are so many other dino-blogs out there, it would be cool if you could do a quick series of posts on how the dietary breakdown was much more complicated than the old carnivorous theropods/herbivorous everything else. Many people probably know there were a fair amount of herbivorous theropods now (after all, there still are), but less are probably aware of the possibility of omnivorous sauropods and ornithischians.

By Karl Zimmerman (not verified) on 20 Dec 2010 #permalink

One of my biologist friends told me about that phenomena when they would catch birds in nets for tagging and measurement purposes. Sometimes they arrive at a net in the field, and a deer would be munching on the birds.

He said it's simply because birds are a good source of calories. Probably their fat is digestible by herbivores.

Most grazers eat a LOT of animal flesh every single day. Of course, if you're all into tetrapods and stuff you may not recognize grass-eating insects as animals, but they are!

On Mann, or one of those other remote British islands, bird conservationists noticed (some years back, before the internet, so I don't have a link) that there were a lot of gulls or terns or whatever with one wing or a shortened wing. On further inspection they also found a lot of chicks with zero heads (they did not survive this). The enigma was studied, and it turns out that the grazing sheep there were regularly grazing of bits of nest-bound pre fledglings probably because of a lack of calcium and/or other minerals in the local soil, and thus, generally, food chain (and dirt ... grazers also eat dust every time they eat anything, which includes minerals).

Because the sheep were good at snipping, the amputations were often clean enough that the chicks would grow to one-limbed adults.

I suppose this could eventually select for two-headed chicks...

greg - did you read the article?? :)

It's the 1988 Journal of Zoology article listed above.

By Bradley F (not verified) on 20 Dec 2010 #permalink

I have a couple of instances that I always felt were odd:

I had a pony who if he was loose in the farmyard when the farm dog was eating would chase the dog away and eat the dogfood which was a mixture of meat and dog biscuits.
I tried to avoid letting him do this because I thought it would make him ill but if he got the chance he would always eat it.

My friend had a Shetland pony and at one time there was a pheasant shoot going on in the area and a pheasant fell into the pony's paddock. When the shooters arrived for their bird the pony had it in his mouth and had already eaten part of it.

Reindeer also catch and eat small birds and mammals. They also gnaw fallen reindeer antlers and sometimes gnaw antlers at each others' heads. And, of course duikers are semi-predatory.

Arabian Oryx munch camel bones, girafe also eat small quantities of bones etc.

About Indian cows: Europeans are unaware that lots of city cows in India rarely have a chance to nibble at any grass or leaves. They feed on paper, torn cloth, household scraps and small quantities of food stolen from market stalls. It was amazing that if you drop a bit of paper in India, the nearest cow turns with interest, comes and eats it.

Well, I'm one European who is certainly aware of this, Jerzy :) Some of my friends watched an Indian cow consume paper and other material from a burning fire... you have to feel sorry for these animals if they are really this desperate.

Interesting comments, thanks everyone.

The local squirrels will eat food.
Many years ago I saw a woodchuck chomping on a rabbit carcass.

"cat food"

well, that's ruined my childhood memories of cow & chicken forever.

Jerzy -- I was at mountaintop a park once where there were a large number of bighorn sheep. I had brought along my sketchbook, and accidentally dropped it over a railing. The bighorns noticed it immediately. One ate the first page -- it was high-quality cotton-based paper, and probably tasted good to a grazing animal. Then a second sheep arrived and challenged him for it. They started dueling over my sketchbook, butting heads enthusiastically.

A sympathetic (if perhaps foolhardy?) park ranger retrieved it while the sheep were still battling over it. I still have it, with a distinct bite-sized chunk missing out of the front cover.

By Calli Arcale (not verified) on 20 Dec 2010 #permalink

Possibly stranger even than this: at a small town in the Caucasus called Neutrino several of us saw a cow eating the ashes from a still burning fire. No shortage of grazing either.

By Chris Clark (not verified) on 20 Dec 2010 #permalink

Jerzy - Re: "Reindeer also catch and eat small birds and mammals." Some years ago I read that caribou (that's what reindeer are called in North America (Grin!)) eat lemmings (and that one of the principles of Arctic ecology is that EVERYTHING eats lemmings!), but can't remember where. Do you have a source you can cite? (It's not all that important, so don't go hunting if you don't know one off the top of your head, but I'd be glad to know of a published source for this factoid.)


Darren in the article and Jerzy have both mentioned deer chewing on antlers: I've long ASSUMED that the only way dear can get enough extra calcium in their diets to grow new antlers every year is by "recycling" the previous year's shed antlers, but never saw mention of this in anything I read. Is there a published source I can cite for this if I ever have to?


The Mountain Pygmy Possum (Burramys parvus) famously has teeth (in particular a "buzz-saw" lower premolar) reminiscent of Multituberculates, so there has long been interest among paleomammalogists in the diet of Burramys as a possible indication of what multis ate. The 1979 survey "Mesozoic Mammals: the first two thirds of mammalian history" even included observations of captive Burramys. Multis are generally assumed to have been, and Burramy to be, primarily herbivorous, but the Australian zoologist providing the observations noted that in captivity Burramys eats meat pies...
Opportunism, one supposes.

By Allen Hazen (not verified) on 20 Dec 2010 #permalink

Cows have evolved pretty amazing physiology, mammal which subsists on paper and cloth... it is not just occassional observation, but main food source for large number of cattle.

@Allen Hazen
I remember it from some general book about mammals... however I don't think that you can say "recycle" in a sense that all or most of calcium from old antlers is directly consumed by reindeer.

@Chris Clark
"a small town in the Caucasus called Neutrino" - sounds like ideal setting for a sci-fi story, I almost expected an almas...

@Ali - interesting you should mention a Shetland pony eating a pheasant. A horse sanctuary local to me had a Shetland who would actively stalk the feral pigeons in the stableyard and bite their heads off. He never seemed interested in consuming the rest of them, though.

All the horses / ponies at the sanctuary in question were rescued from abusive or neglectful situations which I expect would have behavioural consequences. This horse got a reputation as being downright nasty and unsafe. I'm not sure if equines are intelligent enough to be spiteful, but that was the best descriptor for him.

By DunkTheBiscuit (not verified) on 20 Dec 2010 #permalink

Is that chick tied to a string? Seems like a bit of a setup for the camera.

On the other hand, I'm surprised people make a big fuss over herbivores being somehow less evil than carnivores, and getting all shocked and disappointed when they turn out to not be quite so "pure".

I'm just wondering if the cow gets a nasty case of indigestion...

I ran across a reference in a cookbook to an urban bakery that kept a cow glossy and contented on a diet of mostly bread. I had a dog that would happily pick salmonberries (a local variety of bramble) and eat them with relish. I think a lot of animals have a much more flexible diet than conventional wisdom will allow.

By Jenny Islander (not verified) on 20 Dec 2010 #permalink

I know that among rodents calcium starvation is a big deal. So much that the woodchucks at our local RenFest find and stow the bones from the roasted turkey leg remains they find behind the booths and in other niches. Granted, when we find them they are clean, greaseless and dry of any meat, ligaments, cartilage, etc. They DO often have gnaw marks on them.

Dogs are as opportunistic as coyotes or any other canid. they eat everything from fruit to mice to poop to carrion to dog food and the contents of a cat box. (I'm given to understand that cats don't digest all the protein in their food....) And this includes dogs that are fed a premium diet.

The only dog I ever knew that did NOT eat miscellaneous stuff was one we had that had survived Parvo. She would only eat one kind of high-quality dog food because I think she realized anything else caused her grief. The curious thing is that she was a great hunter, she could freaking kill a skunk without getting smelly, and was always bringing my parents carcasses. She just wouldn't eat them. (she was a gigantic Great Dane)

By Paula Helm Murray (not verified) on 20 Dec 2010 #permalink

@21: I'm guessing the string was there to keep them from running off and getting eaten by other, more stereotypically predatory animals.

By Bootstrap (not verified) on 20 Dec 2010 #permalink


a small town in the Caucasus called Neutrino

Do you mean that you were at the Baksan Neutrino Observatory in Russia? Is the town itself (and not just the observatory) really called 'Neutrino'?


I'd be glad to know of a published source for this factoid

I don't have any primary sources close at hand, but Blank (2003) - whom I cited in my earlier comment - lists a few such sources, most of them Russian. Oksanen et al. (2000) also cite a couple of anecdotal reports from Finland and Norway. (Reindeer occasionally have trichinellosis; in their paper, Oksanen et al. speculate that reindeer might get infected by Trichinella when they feed on rodents.)


Oksanen, A., Oivanen, L., Eloranta, E., Tirkkonen, T. & Ãsbakk, K. 2000. Experimental trichinellosis in reindeer. Journal of Parasitology 86, 763-767.



Is that chick tied to a string?


Seems like a bit of a setup for the camera.

Yes, that particular predation event was surely arranged with You Tube circulation in mind.


Multis are generally assumed to have been, and Burramy to be, primarily herbivorous, but the Australian zoologist providing the observations noted that in captivity Burramys eats meat pies...

In the wild, the mountain pygmy-possum Burramys parvus is, in fact, definitely not 'primarily herbivorous'. Smith & Broome (1992) found that 71% of its diet at Mt Kosciusko National Park consisted of arthropods (the rest of the diet consisted mostly of seeds and berries). The diversity of arthropod species in the mountain pygmy-possum's diet was low, however; it was heavily dominated by a single species, the Bogong moth Agrotis infusa.


Smith, A.P. & Broome, L. 1992. The effects of season, sex and habitat on the diet of the mountain pygmy-possum (Burramys parvus). Wildlife Research 19, 755-767.

On a student hike c. 1963, someone roasted a small chicken over a camp-fire. Much was eaten but it seemed underdone inside, so was put back over the fire to cook some more. People went for a walk, and on return found a Swamp Wallaby (Wallabia bicolor) which was sitting in the ashes tearing off chicken meat and eating it. It ate most of what was available.
Several people photographed it. I have since heard of a pet Swamp Wallaby seizing a chicken carcass from an open refrigerator. It defended its capture fiercely.
Swamp Wallabies are believed to eat the contents of birds' nests (eggs and chicks) found on the ground or in low bushes.

By Anthea fleming (not verified) on 21 Dec 2010 #permalink


Just more evidence that the cow is actually attracted to things that are tied to strings.

There is also already a reference in "Grizmek´s Animal Life Encyclopedia", where it is mentioned that up to 10 percent of lemming populations are regularly eaten by reindeers. There is also a very detailed description of a duiker at a swiss zoo which regularly caught and ate birds (of course we all already know that duikers eat meat...). Hares also eat quite regularly mice as well as insects.
Something I learned only quite recently is that dugongs (yes, dugongs!) are also not strictly herbivorous but feed also on marine invertebrates.


There is also already a reference in "Grizmek´s Animal Life Encyclopedia", where it is mentioned that up to 10 percent of lemming populations are regularly eaten by reindeers

Ten percent?! For several reasons, that figure sounds incredible (to put it mildly); what research is it based on?

Hares also eat quite regularly mice

Regularly? Again: reference, please.

No, we were not working at the Baksan Neutrino Observatory. In fact Jerzy got it right: this was part of the 2008 CFZ expedition to Kabardino-Balkaria in search of the almas. We had a grim flat in a concrete tower block that we used as a base. As for the real name of the town, we picked up the name Neutrino from Grigory Panchenko, our Ukranian collaborator, but when I came to write up the expedition for the book I could not find any town called that, so it may be an unofficial thing.

By Chris Clark (not verified) on 21 Dec 2010 #permalink

I have always wondered about the herbivore/carnivore distinction as being quite artificial.
I always learned that carnivores got their vegetarian part of their diet by eating the gut contents of their prey, but, i al ways wondered, where do the herbivores get their protein? Of course a cow is never seen hunting, but while grazing, these animals must ingest vast quantities of insects, worms and other small animalia. It seems like a huge continuum going from herbi to carninovore.

By randomeda (not verified) on 21 Dec 2010 #permalink

Talking of herbivorous animals taking the odd bite of other animals, what does the situation look like for ceratopsian dinosaurs? There seems to be a bit of material floating around the interwebs about the possibility of an omnivorous diet in these animals (e.g. from a post on this very blog and the link to Mark Witton's site).

Greg Laden #7, I'd always wondered how many insects and snails and things grazing animals ingested, and if those things were in fact an important part of their diet. Might grazers be less healthy if they were fed only on grass that had been cleaned of all animal matter?

Re carnivory in herbivores, as a kid I used to feed minced beef to wild kookaburras. One day a crimson rosella fluttered down and picked up a blob of mince and sat there eating it out of its claw. It spun me out a bit, though I see now that Wikipedia reports that they commonly eat insects and their larvae.

By ambulocetacean (not verified) on 21 Dec 2010 #permalink

I knew about Burramys and Bogong moths, heard the story from Linda Broome when we were both in the same department at UNSW. The moths migrate from all over southeastern Australia to the highlands to aestivate, forming vast aggregations in the boulder fields where the possums live year-round - and aboriginal people also used to gather in large numbers for the same seasonal food source (scraped off the rocks in handfuls and tossed in the ashes to singe the furry bits off, they're good tucker).

Edwards and Ealey (1975, Australian Mammalogy 1: 307-17) reported that Wallabia bicolor ate "...every kind of native and exotic vegetation presented to it, not to mention bread, cheese, pastry, roast lamb and muttonfat." This quote comes from Archer, Flannery & Grigg (1985, "The Kangaroo", Weldons, Sydney); I've also heard Mike Archer tell of the one he was keeping as a pet raiding the fridge for roast chicken (see comment 26).

By John Scanlon, FCD (not verified) on 21 Dec 2010 #permalink


Grzimek. [ËgÊimÉk].

what research is it based on?

Grzimek's encyclopedia wasn't based on research. It was based, in its entirety, on anecdotes and "common knowledge".

By David MarjanoviÄ (not verified) on 21 Dec 2010 #permalink


As for the real name of the town, we picked up the name Neutrino from Grigory Panchenko, our Ukranian collaborator, but when I came to write up the expedition for the book I could not find any town called that, so it may be an unofficial thing.

You haven't bothered to find out the correct name of the place you were staying at? Not only is that disrespectful towards your hosts in Russia - it also doesn't give a very good impression of your thoroughness as a researcher. How could others replicate your research if your research sites can't even be found on a map?!

Sorry to be so blunt, but it is a fact that credibility-wise, cryptozoologists face an uphill climb at the best of times; thus, you guys simply cannot afford the luxury of having a cavalier attitude regarding (for example) place names. You must make real efforts to get such things right.

"Dogs are as opportunistic as coyotes or any other canid. they eat everything from fruit to mice to poop to carrion to dog food and the contents of a cat box."
One of our dogs, when young, used to eat the (shed, mostly) fur of another of our dogs.

I also tried offering a pair of gerbils a hot dog and a dog biscuit when I was a kid. iirc, they ignored the former but did eat the latter. One of them ended up partially cannibalizing the other, now that I think about it.

The cow looks starved to me.

Incidentally, speaking of lemmings and reindeer: The Norway lemming Lemmus lemmus has a name that means '(rein)deer mouse' in the Sámi languages that are spoken in Lapland. The etymology behind that name, it seems, is not entirely clear; it's tempting to speculate that 'deer mouse' refers to predation on lemmings by reindeer, but that explanation is most likely incorrect. It's more probable that it comes from the Sámi people's observation that lemmings perform seasonal movements in similar fashion to (wild) reindeer.

#41, really? Perhaps in other dialects maybe, but I've certainly never heard that name for them. We call lemmings goddesáhpan, literally killer mouse, referring to their nasty temper.


We call lemmings goddesáhpan, literally killer mouse

Hmm, interesting. I've been told that the word for the (Norway) lemming in the Inari Sámi language, koddesäplig*, literally means 'reindeer mouse'. What Sámi language/dialect do you speak?

* It's possible that my transliteration is a bit off.

I think the chick was tied to set this up partly as a bet. Did you see the children in the background? One of them collected a piece of paper from another, which looked the right general shape for a bill.

By Samantha Vimes (not verified) on 23 Dec 2010 #permalink

Dartian: in North Saami, the two meanings seem to be homonyms (savve can correct me if I'm wrong). I don't know if the same is true for Inari but maybe 'deer mouse' is a folk-etymological mistranslation of the original 'killer mouse'?

I speak North Saami, the largest dialect group, the western variety of it. Inari is a distinct dialect, pretty different from ours. But kodde and godde seems alike, and goddet means "to kill" :)

A personal observation:
First, in my area live many testudo hermanni tortoises.
Before two years, a medium-sized t. hermanni was hit by a car and died. Someone put it at the side of the road. It decomposed in the next two weeks, with many flies and insects. Finally, only the bones remained, but they also started to disconnect and scatter away. Was a coincidence that big heavy female turtles were near the area? They might chew on the bones for calcium for their eggshells, as many tortoises do.
But the notion that there is no absolute herbivory may be detrimental for animals in captivity. If, for example, you feed herbivorous reptiles such as tortoises and iguanas animal protein in captivity, they will develop liver and kidney problems and obesity. Even the wrong types of plants can harm them.

Reindeer (in general) are called boazu (sg) or bohccot (pl), so the homonym theory doesn't quite fit. Boazu and goddet do not sound the same at all.

Well I just came across this piece by Brian Switek in the Guardian, it is hilarious to see the reaction in the comments to a "strictly herbivorous" Styracosaurus depicted eating carrion...

(Also the comment about how large animals should be depicted in greys, I guess the point about mammals having pretty poor colour vision among vertebrates needs to be made more well-known,,,)

Did the cow have to regurgitate the chicken, and chew the cud? Which stomach would handle the meat?

An herbivore like a reindeer would not be able to properly digest the muscle fibers in meat. The hydrochloric acid in an herivore's stomach is much weaker than in the stomach of a carnivore or an omnivore, and the digestive enzymes are different. I suspect that the meat would probably either be vomited up, or passed through the intestines virtually undigested, providing little nourishment.

Have a citation for the bit about weaker HCl in reindeer stomachs and different digestive enzymes? Not saying that I know differently for certain (my ruminant physiology references are back at the office), but that doesn't square well with what I have learned (earned a PhD in ruminant nutrition some years back). Prior to the mad cow event in Britain, it was common practice in the U.S. to feed material derived from blood and 'offal' (from carcass disposal) back to cattle in feedlots. This mixed with grains and other plant sources, of course. Performance of these animals was reported to increase under that kind of management, apparently in part due to the fact that the amino acid profile of the fed animal tissues were more similar to ruminant requirements than what the plants supplied, and somewhat more of the amino acids would 'escape' the rumen without being fermented and altered by rumen microflora. I believe that it is still legal and practiced in some southern states to "compost" and feed dead poultry to cattle.

Also, nutritionists have long debated the cause of what is often called (somewhat incorrectly, in this case) "pica" in animals, where animals eat things they aren't 'supposed' to be eating. Pica properly refers to materials that have no nutritive value, but I have heard this matter of herbivores deliberately eating animal tissues described as 'pica' in publications and conversation. But clearly herbivores are perfectly capable of ingesting and nutritionally benefiting from that activity, even if their hardware makes them rather less efficient at it than carnivorous species.

When netting for bats there are several reasons to try and keep deer away from your nets. The most obvious is entanglement, but I have a colleague who came upon a deer eating a bat that had been caught in one of the lower shelves.