It's a term that is thrown around A LOT these days. Grass-fed, grass-finished, grain-fed, pastured,naturally raised beef, lamb, butter, dairy, and pork. It seems like it's quite obvious what it means doesn't it. In my adventure into the best way of feeding dairy sheep, I decided to take a look into the "official" meaning of grass fed. Yes, there is an "official", and it's not as straight forward as I thought.
Grass-fed has different meanings depending on what's being talked about. Grass-fed meat may be on a spectrum on how grass-fed is grass-fed. Before delving down this rabbit-hole though, I'll give a bit of a ruminant rundown and a few things to think about that isn't obvious.
Cows, goats, and sheep are all ruminants. That means they have a multi-chambered stomach, including a rumen, that contains bacteria to break down the plant matter they eat. To break down that matter they regurgitate their food repeatedly and chew it. This is called chewing cud. Despite them all being ruminants. These animals can also be categorized into meat and dairy. As simple as it seems, it isn't. Dairy animals produce milk, meat animals are raised for meat. What can muddy the waters is things like "dual purpose", and "heritage breed". These labels can have an impact of what we think the animals can do. Even the word breed implies a set standard - which it is...kinda.
An animal's breed, species, and purpose all play important roles in how it needs to be fed. A milk animal will by default need more energy dense food than a meat animal. Her body uses much of the energy from her food into milk which is harvested daily. A meat animal has a much easier life. It eats, gaining weight for months. A fibre animal that isn't for meat or milk, puts it's food energy into fibre. One animal can't do all of that well, it's just too much to ask.
First we'll look at the use of an animal. You probably wouldn't want a chihuahua trying to pull a dog sled through the snow, nor a beagle being a guide dog that will pay attention to your needs. Each dog has talents that have been selected for over time. As an aside, most true breeds have only been developed since the 19th century, but that will wait for another time.
Livestock is similar. A milk animal is known for producing lots of milk. Milk animals have very similar characteristics no matter the breed. They are often taller, lighter boned, bony, thinner, even at peak condition. The final noticeable characteristic is that they have large udders. These animal are prized because they have plenty of milk for their young, and enough extra for us. Animals that had a lot of milk were selectively bred to produce a lot of milk. The older animal are the ones that have the most value in the food system. The best of the young are kept to replace the aging mature animals, and the rest of the young animals are eaten. A milk animal can be on a farm for years, especially if she is good.
A meat animal is just that, one that is bred for meat. Meat animals are known to be heavier boned, more muscled, have more fat, and have small udders. Their milk often has a higher fat content, but there's a lot less of it. The best cuts come from the young animals. Older animals of both types often go to ground, stew, and sausage as long as they pass government inspection at the abattoir.
Ruminants have some constraints that monogastric (single chambered stomach) animals don't. Ruminants need time to absorb energy from their food. All that chewing, swallowing, and regurgitation of plants takes time. Their rumen expands to digest food. Their stomachs takes up A LOT of room inside them, especially when eating, fermenting. When pregnant, the babies take up some of the room that the rumen used. A ruminant often can't physically eat enough to keep them going if pregnant, especially if there is more than one baby.
Each species and type of animal needs an optimum feed to be as healthy as possible. This ration has five major components. They are
plus water. Milk animals need a different combination of thee above items than do meat animals. Due to poor weather (drought, rain, timing), soil quality, or a host of other things, straight forage (hay or grazing) may not fulfill the needs of the animal, or the desired needs of the animals. The more energy dense the feed, the faster the animal will gain weight or have enough energy to sustain milking. This is why high nutritional value grains like corn and soybeans are fed to animals. Of course there are more grains that can be fed to animals than just corn and soy. More traditional grains like oats, barley, wheat, grain chaff, brewers grains, sunflower seeds and many other waste products from other processes have been fed to livestock. It can get quite complicated.
Finally, for meat, the focus is on younger animals. Beef cattle are most often around 18 -22 months old when harvested, meat goats around 7 months, and meat sheep anywhere from 3 months to 14 months, depending on breed. The age at which goats and sheep go in seem young I know, but they are often sexually mature at around 4-6 months of age. Most meat producers want the young out of the barn as quickly as possible as the majority of income comes from those animals.
Milk producers deal with young animals differently. Firstly, the young animal aren't just for meat, but also to replace breeding stock. Usually it's the females that are kept, but the best males can also be kept. Gaining weight as fast as possible isn't always good for female milk animals. If they gain too much weight, their udder actually gets fatty. In the future the fat takes up space where milk could be. A few common ways to manage young animals are keeping them on the dam (mother) for short periods of time (enough to get enough colostrum usually 1-3 days) and then separate them into groups and feed them milk from the milking or milk replacer, or keep the young on the milk animals for a time, and wean when the rumen is developed enough to eat regular food while milking the milking once or twice a day.
Of course there are a multitude of combinations of how to manage animals depending on size, location, animals, need, etc., etc., etc. Each farm is different and depends on species, and management style. Both meat and milk animals have their own unique challenges regardless of the species, or breed.