Domestication through Mendelian Inheritance Revisited

[Balthizarlucien 49]

Domestication through Mendelian Inheritance Revisited

 

In my previous posting of this suggestion I went into decent detail regarding Gregor Mendel and his work. Since I am revisiting this topic I shan't repost that which need not be posted however, I have made some revisions which should tune this more towards the upcoming work which is needing to be done with regards to animals.

 

What I am proposing is a set of traits which each wild animal shall possess which will enable the breeding of wild fauna into livestock. With this kind of framework you are able to create breeds which are unique to your world and fit the tasks you are hoping to breed your animals for. The best part is that each distinct sub variant need not be hard coded so long as the framework from which the animal's traits are retrieved is properly constructed. As an example, five distinct states of a single feature can yield 120 possible combinations...

 

I am a professional coder who has some experience with Java though I have never written a Minecraft mod before. Knowing code and programming logic this type of feature could potentially be quite light and need not be as burdensome as it has the potential to be.

 

The traits I believe would be most useful are listed here:

• Size

• Color

• Horn/ Tusk/ Antler/ Spur Size

• Temperament

• Number of Offspring and or Fertility Rate

• Natural resistance to hot or cold climates

• Strength

• Intelligence

• Perception

• Volume of Production

 

Each of these traits can be sub divided into recessive and dominant genes and because my Menagerie listed below are all real animals much of it already has been. Those which refer to purely game statistics of course would need to be determined to fit the proper desired game mechanics as wild animals should still breed amongst themselves but I will describe each trait below for you as I am sure some sound a bit vague.

 

Size

 

This one is fairly straight forward. Size typically is a trait in the wild which leads to either dwarfed or giant versions of animals and which allows humans to breed chihuahua dogs that fit into a tiny purse. Of course what part is dominant and what part is recessive in the wild is mostly based on living conditions. Island Dwarfism is the result of a limited amount of space, food and water. The megafauna of the late pleistocene was due to an over abundance of grass like foods. If you are looking for smaller animals then breed smaller mates but in the wild bigger is typically always better.

 

Size was used in TerraFirmaCraft's previous iteration and could easily be adopted again as it was code light and efficient.

 

Color

 

This one plays into another feature further down the list but is very important when you think about it. Animal colorations all mean something. A white tailed deer is a soft brown so that it can blend into its forest surroundings without worrying about predators being able to pick the deer out but; they also have a striking white tail. This is a warning to the rest of the deer that there is danger and that the herd must flee. So, color could be a warning or camouflage depending on what it is used for. 

 

Color can also be quite easy to implement as well because you can use a palette function on a black and white skin calling two, three or more distinct color zones. This could yield some very interesting looking animals. Also the currently utilized overlaid skin technique used in displaying food of certain doneness could be used for coat/scale/skin patterns. This would allow for things like spots, stripes etc to be introduced easily. 

 

Horn/ Tusk/ Antler/ Spur Size

 

Size is again important. If you wanted a boar as a guard animal (they are very dangerous animals for those who may not know) then you may wish to breed males with larger tusks so they can do more damage. For those of you who are tired of taking damage from a freshly domesticated Junglefowl may be looking to breed that annoying spur right off the rooster’s foot. Again is it entirely up to what you want. Now I know that spurs will not be able to be included in the model but you could simply vary the damage it does so that if someone wanted a flock of attack chickens they could breed them that way. 

 

Other variations could be included for these distinctive features such as varied horn shape, size or position.

 

Temperament

 

This one is very important and we actually have a study to go from that took place in Russia where they eventually bred a tame fox species. [http://en.wikipedia....ated_silver_fox] Temperament determines how aggressive or docile a species is. In the wild aggressive behavior can be a huge benefit, especially to solitary animals but on a farm, it can be highly dangerous. You can breed out aggressive tendencies by simply removing more aggressive animals out of the breeding pool and onto your dinner plate. Eventually you will have yourself a docile, friendly version of the animal which will not attack you every time you walk by. 

 

Number of offspring and or fertility rate

 

I have played and watched enough terrafirmacraft to think that I may want a pig that does not cause a pig-splosion every time she gives birth… and having a few extra cows would be nice. With this trait you can breed towards a high chance of producing less or more offspring simply by continuing to breed a line that produces at the rate you wish. In the wild having more babies is beneficial to more aggressive animals but for herds of grazers, having less is better as it permits the herd to protect their young better.

 

Natural resistance to cold or heat

 

This one would be a fun feature to play around with because you could breed shaggy cows or hairless dogs! It really depends on what you are looking for. This gene would be climate specific in the wild and would control fat and hair production so if you are planning on breeding larder pigs then you are going to want to get them from colder areas but if you would rather produce mutton and milk as opposed to producing wool then you would need to find yourself some warmer climate sheep. 

 

Things which display this could be fatter animals, shaggier coats, perhaps a leaner more toned animal. these features could easily be included.

 

Strength

 

Right now there is no way for you to hook up a cart to an animal or to use an animal to pull a plow but you can use donkeys to carry things for you. I would personally love to see other modes of transportation and I am sure lots of people would be behind me on this one but otherwise this gene may be useless by itself. Strength is self explanatory and could be used to improve an animal’s carrying capacity. Pack animals have been used by man for eons and are included within Minecraft with the donkey. You could use these mechanics for horses, goats etc.

 

Intelligence

 

I know I promised not to talk about AI but it is a bit hard to avoid. The reason this one is so important is because “smart” farm animals are typically harder to contain but are excellent students when trying to teach them how to perform certain actions such as riding or truffle hunting. This would be something that would allow you to fine tune your animals a bit easier for the jobs they are to do and would come into real play when dealing with any of the animals you would like for pets. Mechanics wise it could be a trait used for setting the difficulty in learning tasks such as riding, hunting etc.

 

Perception

 

This is a gene that would be exceptionally useful in the wild. It has three main components: Sight, Hearing and Smell. This is how we took a wolf and created the bloodhound from it. If you are planning on hunting truffles then you will want to take your docile pig line and breed the ones who have the higher success rates when finding truffles in the ground with their snout. If you want a falcon to be your hunting partner then you will need to breed those which are good hunters (they rely on sight). These features are the ones we typically breed our pets for but could apply to a bunch of different breeds and can be effected indirectly by things like longer hair length. 

 

Volume of Production

 

This one is one which I actually saw a mod for a long time ago. This is the set of genes which determines output of meat, wool, milk etc from your animals. By using this gene correctly you can increase your yields or create varied sources for certain products like milk. I am sure that many people know about cow and goats milk but were you aware that sheep are also used for milk production? If you said yes then the chances are relatively high you are not from the United States as sheep milk is exceptionally rare here. But wouldn't it be cool to have a dual purpose animal on your farm that gave you two renewable products? I sure think it would be. 

 

Player GUI

 

As for player GUI implementation, I was thinking that not much would be necessary. simply a skill that can increase with different interactions with animals such as feeding, breeding etc. This would be similar to the existent system for seeds which have them displaying a specific nutrient when your agricultural skill is high enough, you could tooltip the gene data of the animal at a certain husbandry level. This would of course be difficult to exploit but would give people a way to see where their animals are within the genes and breed accordingly. 

 

I believe that adding this system fully into TerraFirmaCraft 2 would broaden not only the diversity of animals available but the customization we want.

 

 

Aurochs

 

 

 

 

Fertility                               40-60% chance

# of Offspring                     One, twins 1 in 7

Gestation                             72 days (adjusted for 96 day year)

Eyesight

        bad depth perception (will stop at shadows)

        normal color perception (better at seeing short wavelength)

        good movement acuity 

        300 deg vision

 

Hearing                                  23-35,000 Hz

Smell                                     Far (16 chunk range)

Diet                                          Herbivore

Primary Predator              Wolves

Climate                                  Temperate Forest/Grassland

 

Male

Height                                    160 - 180 cm

Weight                                    700kg - 1500kg

Distinct Feature

        Large pronounced horns which curve toward the front

     

Color

        Black-brown with a small light eel stripe

 

Product

       Beef

       Work Animal

       Leather

 

Mating habit

       Males duel horns for dominance in mid to late summer

     

Social behavior

       Solitary during most of the year

 

Female

Height                                  135-150 cm

Weight                                  500kg - 1000kg

Distinct feature

       Small Udder

       Smaller Horns

 

Color

    Reddish Brown

 

Product

      Milk

      Beef

      Leather

 

Social behavior

      Unisexual herd to protect offspring

 

Further Reading:  https://en.m.wikipedia.org/wiki/Aurochs

 

 

Bezoar Ibex

 

 

 

 

Fertility                                90% chance

# of Offspring                      One, 1 in 4 twins

Gestation                              40 days (adjusted for 96 day year)

Eyesight

        Excellent depth perception

        Excellent color perception

        Excellent movement acuity

        340 degree vision

 

Hearing                               78hz - 37,000hz

Smell                                     Far (16 chunk range)

Diet                                          Herbivore

Primary Predator              Mountain Lion

Climate                                  Temperate Mountainous Regions and Conifer Forests

 

Male

 

Height                                   85cm - 100cm

Weight                                    80kg-100kg

Distinct Feature

       Large, keeled scimitar horns as long as its body

       Pronounced Beard

     

Color

       Range grey to reddish brown turning to whitish with age

 

Product

       Chevon (goat meat)

       Leather

       Pack Animal (like donkeys in vanilla only less carrying capacity)

       Cashmere (soft goat hair which makes an excellent insulator)

 

Mating habit

       Males duel horns for dominance in mid to late summer

     

Social behavior

       Solitary during most of the year

 

Female

 

Height                                   60cm-80cm

Weight                                   25kg - 40kg

Distinct Feature

       Small Udder

       Smaller Horns

 

Color               

       Reddish Brown

 

Product

       Milk

       Chevon (goat meat)

       Leather

       Cashmere (soft goat hair which makes an excellent insulator)

 

      Social Behavior

              Unisexual herd to protect offspring

 

Further Reading:  https://en.wikipedia.org/wiki/Wild_goat

 

 

Wild Boar

 

 

 

 

 

 

Fertility                                 40-60% chance

# of Offspring                       4-12

Gestation                               37 days (adjusted for 96 day year)

Eyesight

        bad depth perception (will stop at shadows)

       no color perception  

        Poor movement acuity

        300 deg vision

 

Hearing                                  40hz - 40,500 Hz

Smell                                       Far (16 chunk range)

Diet                                          Omnivore

Primary Predator              Wolves or Large cat (ie Mountain Lion)

 

Climate                                  Boreal to tropical

 

Male

Height                                   100cm - 125cm

Weight                                   300kg - 350kg

Distinct Feature

      Large tusks protruding from lower jaw

        Thick mane running down the back  

 

Color

      Light Rusty Tan to Black-Brown to Reddish Brown

 

Product

       Pork

       Lard

       Leather

 

Mating habit

     Males fight for dominance in winter.  

 

Social behavior

       Small loose knit packs

 

Female

Height                                 85cm-105 cm

Weight                                  210kg - 250kg

Distinct feature

       Large tusks protruding from lower jaw

       

       Thick mane running down the back

 

Color

     Light Rusty Tan to Black-Brown to Reddish Brown

 

Product

      Pork

      Lard

      Leather

 

Social behavior

      Unisexual herd lead by old matriarch to protect offspring

 

Further Reading:  

 

 

[/Spoiler]

I have cleaned it up bit and have added spoiler tags to each animal. Now that I have this format the rest of the animals I will list should come fairly quickly. 

 

Edited 24 Oct 2016 by Balthizarlucien

[Miner239 47]

Woah, mate, spoiler that thing.

 

If volume of production is in, will that also mean weighted wool, milk-in bucket, and so on? I'd like that. 

[Darmo 303]

It's unclear to me what size does - does it vary the meat yield and/or hide size?  If so does that stack with production?  I would think you might not want production to affect meat yield or hide size. 

 

It'd be a fun system of course, though a lot of that stuff seems to me marginally useful.  To me Size, Color, Temperament, Strength, and Production sound like the most useful ones.  Speed and jumping height also, though they're not in your list, probably because they're only really relevant to horses.  Well, color isn't really 'useful' per se, but I think it'd still be nice to have.  I like the large variety of horse colors that currently exist, and wish they didn't just always inherit the mother's color.

 

Aggression could definitely be a balancing factor in the beginning.  I'm not entirely sure how you'd gather the animals in the first place if they're too aggressive though.  Camp out by them until you have them familiarized enough to bring them home?  That basically would make the aggression trait just an initial stumbling block, as every subsequent generation is likely to be domesticated enough.  Pigs are well known for reverting to boars pretty fast when they escape to the wild though.  It would be pretty interesting if their skins was initially boar-like, and only changed to the pink pig over time.

 

The new animal types...I'm not sure what they're bringing to the game. (definitely would be nice if they were spoilered)  They seem kind of like existing animals with different models, with some pack carrying capability for the ibex.  I thought they were tropical versions at first, then noticed you gave both climates as temperate.  I don't know what the intent in TFC2 is, but currently temperate climates already have all the animals, it's the topics (and poles) that are extremely lacking (a balance choice for the tropics, from what I understand).  I'd definitely love to see new animals, don't get me wrong.  But I'm hoping the tropics can get some variety.  TFC2 will have umbrella acacia, so that opens up the field for a variety of savannah animals I'd think.

[Balthizarlucien 49]

I will be expanding the animals over the next few days and there are animals in every climate range included.

It's unclear to me what size does - does it vary the meat yield and/or hide size? If so does that stack with production? I would think you might not want production to affect meat yield or hide size.

Production would not effect the quantity of meat or the size of the hide as those are not products from the animal but instead parts of the animal itself. Those aspects should be size based.

... Aggression could definitely be a balancing factor in the beginning. I'm not entirely sure how you'd gather the animals in the first place if they're too aggressive though. Camp out by them until you have them familiarized enough to bring them home? That basically would make the aggression trait just an initial stumbling block, as every subsequent generation is likely to be domesticated enough. Pigs are well known for reverting to boars pretty fast when they escape to the wild though. It would be pretty interesting if their skins was initially boar-like, and only changed to the pink pig over time.

As with Wolves now, the first few would never fully familiarize with you. They just will stop trying to kill you >

The new animal types...I'm not sure what they're bringing to the game. (definitely would be nice if they were spoilered) They seem kind of like existing animals with different models, with some pack carrying capability for the ibex. I thought they were tropical versions at first, then noticed you gave both climates as temperate. I don't know what the intent in TFC2 is, but currently temperate climates already have all the animals, it's the topics (and poles) that are extremely lacking (a balance choice for the tropics, from what I understand). I'd definitely love to see new animals, don't get me wrong. But I'm hoping the tropics can get some variety. TFC2 will have umbrella acacia, so that opens up the field for a variety of savannah animals I'd think.

The point of the animals listed here is simple, they would replace the current animals and then using these you can try and breed a dairy goat or attack chickens etc. that is the beauty. And considering we do not have goats at all in Minecraft the bezoar ibex would be entirely new Edited 30 Aug 2015 by Balthizarlucien

[sthegreat 1]

Yes... this would be amazing. Right now animal farming is like vanilla but more time consuming but this would add a lot of depth and make farming require more skill.

[Thorah 6]

Very interesting, it would certainly add a lot more depth to the system. As far as time scale is concerned, I think we'd have to key it in with the rest of the system to ensure you could get animals when they were useful, and that there were a few niches only the animals could fill.

 

Variety

I'm a massive fan of variety even if it's only aesthetic.

Implementation of the colour variation would be a great aesthetic benefit it's as easy as that but I'm not sure that Minecraft can handle creating a new texture form two previous ones. Awesome if it can. Perhaps a workaround could be simply having the community create a large variety of coats for the various animals and then have the computer somehow infer a set of coats logically similar and randomly pick from that.

 

Intelligence

Intelligence seems to be the most difficult to implement. Perhaps we could simplify it by having a system that allows for a set of specific but useful behaviours they could have.s Effectively creating a subset of each animal. Then a pig could have any of traits 'flee', 'truffle hunt', 'fight', 'advanced pathing', 'extra sight range', etc. That could also include the personality aspect if implementable.

 

Production

I like the idea of having a variance in production. That would add an interesting element.

 

Balance

I think that a genetic system such as this would need balancing in a simple manner to ensure that it wasn't merely an inconvenience until you'd perfected the breed, or excessively drawn out.

That could done by balancing for length of time to breed relative to other milestoness. Alternatively perhaps having certain axes on two ends of a scale would ensure you could only breed stupid animals with high production, or small animals with great intelligence. Thereby ensuring the system can't be exploited excessively.

 

Interface

Do you have any idea to incorporate a manner of observing this. Were you thinking it could all be done intuitively by observation, or that it needs to be explicitly detailed by means of an item or GUI.

A smooth manner that we could use would be to tie it to the generation of the skin. Aggressive boars having darker skin, and higher production sheep having less flecks of other colours in their wool.

 

Overall yeah I like it. Would be very cool to see in the game.

[Darmo 303]

Just to add a couple other thoughts; bad temperament/aggression doesn't necessarily have to mean toward the player - which if we're being honest would be only an annoyance in many cases, not a true danger.  The aggression could be toward other animals as well. 

 

So especially aggressive males will attack any other same-species male they see, and other animals in general sometimes.   Aggressive females become extremely aggressive towards other species when they have just given birth.  Moreover, aggressive animals could attack and destroy wooden fences and gates, requiring stone walls or other means to pen them in.  So then even an aggressive pig becomes  a problem because it might kill other pigs, or destroy fences letting other animals roam free.

 

Also, bad temperament could mean the animal is very hard to rope.  It sometimes seems like this is the case already, as some animals seem to take several tries for the rope to stick.  Though this could be my janky mouse.   But it would be another way to reflect bad temperament in a way other than attacking the player.

[subarctic_guy 18]

Alternatively perhaps having certain axes on two ends of a scale would ensure you could only breed stupid animals with high production, or small animals with great intelligence. Thereby ensuring the system can't be exploited excessively.

 

 

... or only have a pool of genetic "points" limited so that no one animal could max out all traits.

 

I think a measure of random mutation would keep things interesting, so that you would have to work to keep a breed (say, miniature attack chickens) pure as over many generations a breeding population would tend toward average traits. And then every now and again you would have a mutant from an average pairing. Two wild chickens give birth to the one-in-a-million MEGA-CHICKEN.

 

[cjhc12 6]

Brilliant idea !!

[Darmo 303]

The recent discussion in the animal husbandry thread gave me some more thoughts about animals traits.  Right now, without being attacked, only deer run away from the player.   However, if animal taming were changed, temperament could become more relevant.  Right now all you need is a tiny bit of grain and you're in the animal game.  What if all wild animals fled from the player if the player gets too close?  Or at the very least, won't follow held grain?  What the player has to do is toss out a piece of grain (keeping in mind that grain will no longer be in ounces in TFC2, but in discreet pieces - I'm assuming one piece is equivalent to TFC1 5oz.), which, if the player backs far enough away, the animal will come and eat - I'm going to refer to this in this post as "familiarization", and the process of actually progressing the heart of the animal, as "taming". 

 

The idea is to make obtaining animals a bit more costly.  But as a side effect, it would make early game animals harder to kill.  You wouldn't be able to just walk up to a pig and slaughter it.  It would run.  This would incentivize the player to make javelins in the early game (in TFC1 I never both with javelins).  The player could probably still work out clever traps to run the animals into to get close enough for melee, but at least it would take more work than it does now.

 

But back to animals the player actually wants to domesticate, depending on the temperament characteristic of the animal, the player may have to toss out a piece of grain several times.  After they've done it enough times, only then will the animal allow them to approach, follow outheld grain, or allow the player to attempt to rope them.  This tossed familiarization grain also does *not* advance the taming progress - though once they've been familiarized enough for the player to approach, then the player can start feeding them to tame them (this taming feeding also keeps the familiarization topped off).   However, familiarization is only temporary as long as the animal has not been tamed to yellow heart.  Depending on the animals temperament, the familiarization grain wears off over time.  If the animal is mild-tempered, maybe it's another 2-3 days before the player has to toss them another grain to get them familiarized again.  but if it's a very wild animal, maybe half a day.  So a very ornery animal could lose familiarization fast, meaning that the player has to keep tossing them grain once in awhile, even while taming them, because the familiarization goes down faster than the taming.  But a mild tempered animal, the familarization will go down slow enough that the taming grain will keep it topped off.

 

Now for horses at least,  it could be that traits like speed and/or jumping ability are linked to temperament (upon generation), making the wildest horses, at least, worth the effort and grain of taming.   Temperament goes down over succeedingly bred generations, so the player can breed tamer horses, but the speed and jumping do not go down (they're only linked to temperament upon initial spawning). 

 

Temperament could also come into play when trying to rope an animal, with wilder animals resisting it (even if familiarized), or attempting to break the rope if they drop out of familiarization while already roped.  And of course, worse tempered horses (and other rideables) take longer to saddle break.

 

In general, this sort of thing would make animal taming take more grain.   If there are more animals in TFC2, then the player may need to pick and choose which animals they domesticate first, with their limited grain supply, based on which ones have the best temperament.   Also, an animal born to two tamed animals should probably always have a minimum tameness so the player does not have to toss them grain anymore.  The running from the player thing, I don't know if that will bog down the processor a bit due to animals having to scan for where the player is at.  But anyway, there's some thoughts on how temperament could affect domestication, and also increase the need for early game missile weapons.

[lJuanGB 13]

 

 

... or only have a pool of genetic "points" limited so that no one animal could max out all traits.

 

I think a measure of random mutation would keep things interesting, so that you would have to work to keep a breed (say, miniature attack chickens) pure as over many generations a breeding population would tend toward average traits. And then every now and again you would have a mutant from an average pairing. Two wild chickens give birth to the one-in-a-million MEGA-CHICKEN.

 

 

I have to say that I don't like the random gen idea. It is implemented in vanilla for horses, and it makes the breeding of horses really difficult. In a server I planned to work as a horse tamer, and then provide the best of horses by crossing better and better horses... The theory is good, but at the end I always ended with just slightly better horses, which no one wanted, as they could find better ones in the wild with a bit of luck.

However, if we are looking for something more complez than A+B=Mix of AB, we could add the "genetics" things. It is a thing we learn in elementary school:

 

For every trait, animals not only have their gens, but also the gens of their parents, even if those doesn't manifest. Let's say:

Gen T is for big horns, Gen t is for small horns. T is dominant over t. The male has the gens of his fathers T and t, both at the same time, but just T showing. The female will have T and t. Now the breed could be:

We can see that 3/4 times the baby will have big horns. 1/4 times he will have them short. 2/4 times their gens will be "pure", which means that their offspring will no longer have the other trait.

 

This surely adds complexity, but is kind of a more interesting system that doesn't include random things.

[Donjons 7]

I love the idea

[TonyLiberatto 364]

One way I see this to be really interesting and rewarding to the player is if by select procreation the player could acquire animals that otherwise would not be found in the wild.

Even though man found Arouchs in the wild their cows would not give as much milk as modern cows do it.

What if cows at first only give 1 Lt of Milk 1/5 of a bucket. As you keep breeding cows for better you would finally get to the best and would have a full bucket of milk.

The same principle could be applied to all other animals.

[subarctic_guy 18]

It sounds like the mutation in vanilla horses is way too high. I was thinking it would be a rare event and a way to get traits you probably wont find in the wild.

I also like the idea of dominant and recessive genes and maybe even multi-gene traits. Then experiments with line breeding and hybidization would be meaningful.

[Darmo 303]

I agree with Tony, it'd help make breeding meaningful if it were the only way to obtain top producing/performing animals.  In this context it would be very good if the bucket could hold less than 1000mb quantities.  Maybe increments of 200, or 250.  Maybe the top-producing natural milk animals can do 1k, but through better breeding an animal could produce up to 2k per day.  It'd also be an opportunity for actively feeding the animal to increase production.

 

TFC2 could definitely use some changes to make animal products more meaningful.  As it is, wool and meat are fairly easy to produce in quantities that make genetic variation kind of meaningless - food is easy to get after awhile, and wool only has two real uses, only one of which could be considered ongoing.  Leather is also very limited in usefulness.  Milk is a little more important on an ongoing basis, but still, once you have a few cows, you'll be able to produce it pretty consistently.   Presumably leather and wool could become more useful if temperature and clothing make it into the game.

[TonyLiberatto 364]

What if we had something like wear and tear? The way the game is set today, if you never go in combat your leather armor will last forever. 

To make wool more meaningful like for example warm clothes for cold weather it would help if those clothes would need replacement after some time. Otherwise once you make a full set of wool clothes you would be done with wool.

Since as I understand weather would be variable, the player would not be wearing the same outfit for the whole day, so maybe instead of making clothes tic or have an expiration time the best way to handle would be to apply damage every time you put the clothes on or take it out.

Sorry to mix the animal procreation with clothing, but we need more uses for animal products if we want to have the player invest time procreating animals. 

[Cattleman 11]

One way of making genes not op is actually looking at real life. Realistically a cow that produces lots of meat shouldn't also produce lots of milk because the energy demand is too high, so a milk cow will stay skinny