Animals and Agriculture Environmental Science Chapter 15 Section 3

Animals and Agriculture  Remember, the total energy needed to grow plants for food is much less than the energy needed to raise animals as food.  Most humans include some animal products in their diet.  Our ancestors obtained animal proteins by hunting and fishing.  Now, most people get animal proteins from domesticated species.  Bred and managed for human use.

Food From Water  Fish are an important food source.  When too many fish are harvested over a long period of time, ecological systems can be damaged.  Overharvesting  Catching or removing from a population more organisms than the population can replace.  Many governments try to put an end to this.  No-fishing zones – fishing will improve in areas around these after only a few years.

Aquaculture  The raising of aquatic organisms for human use or consumption.  Not a new idea.  China leads the world in using aquaculture to produce freshwater fish.

Aquaculture  Methods  Fish farm  Generally consist of many individual ponds that each contain fish at a specific stage of development.  Clean water is circulated through to bring in oxygen and remove wastes.  Fish grow to maturity and are then harvested.  Ranch  Fish are raised until they reach a certain age and are then released.  Ex: Salmon will be released, live downstream, then return to reproduce, where they are captured and harvested.

Aquaculture  Most of the catfish, oysters, salmon, crayfish, and rainbow trout eaten in the U.S. are the products of aquaculture.  Worldwide, about 23% of seafood.  Problems  Pollution – large amounts of waste.  Water usage – require large amounts of water.

Livestock  Domesticated animals that are raised to be used on a farm or ranch or to be sold for profit.  Chickens, sheep, cattle, pigs, goats, horses, donkeys, mules.  Provide leather, wool, eggs, and meat.  Can also be used as draft animals (pull carts and plows).

Livestock  Ruminants  Cattle, sheep, and goats.  Cud-chewing mammals that have three- or four- chambered stomachs.  Hundreds of breeds of cattle that are suited to life in different climates.  Not always used for meat – milk, blood, dung, draft animals.

Livestock  Poultry  Domesticated birds raised for meat and eggs.  Usually raised in factory farms.  Criticized because of cramped, artificial environment.  Ducks and geese.  Ducks’ droppings are used in China to fertilize rice paddies.