Ecosystem Nutrition and Energy Flow

Feed Conversion Ratio (FCR) is a measure of an animal's efficiency in converting feed mass into live weight gain (LWG). A lower FCR is desirable because it means the animal requires less feed to produce a kilogram of weight gain.

A production diet is the additional feed required by an animal above its maintenance needs to produce milk, meat, wool, or work. For growing animals, this extra energy and protein directly support live weight gain (LWG).

A maintenance diet is the minimum amount of feed required to keep an animal alive and at a constant body weight without any gain or loss. It covers basic metabolic functions, respiration, and body temperature regulation.

Metabolizable energy (ME) is the portion of feed energy that is actually available for the animal's body to use after accounting for energy lost in feces, urine, and digestive gases. It is calculated as digestible energy minus energy lost in urine and methane.

Ruminants, such as cows and sheep, have a complex stomach divided into four compartments (rumen, reticulum, omasum, and abomasum) to ferment fibrous plant material. Animals with a single simple stomach are called monogastrics.

Microbial contamination in raw pet food is a significant public health concern for humans in the household as well, due to the risk of direct contact with the food, contaminated surfaces, or pathogens shed in the pet's feces and saliva.

Concentrates, such as cereal grains, are dense in energy and highly digestible, meaning they are fed in relatively low quantities compared to fibrous feeds. They provide a high concentration of nutrients per unit of weight.

Roughages, such as pasture grass and hay, are high in fiber and lower in digestible energy, requiring animals to consume them in larger quantities to meet their nutritional needs. They are essential for maintaining proper rumen and digestive health in herbivores.

Abiotic factors are the non-living chemical and physical parts of the environment. The Sun is a non-living energy source, whereas trees, worms, and puppies are all living (biotic) organisms.

In a food chain, primary consumers eat producers (plants). Secondary consumers eat primary consumers.

Producers, such as plants and algae, are the organisms that capture solar energy through photosynthesis to create chemical energy.

Secondary consumers obtain energy by eating primary consumers, which have already consumed photosynthetic organisms (plants).

Phytoplankton are producers. When fish consume them, they obtain the chemical energy stored within the phytoplankton.

Plants are autotrophs, meaning they use photosynthesis to convert sunlight, water, and carbon dioxide into glucose, effectively making their own food.

Bees are heterotrophs, meaning they consume other organisms for energy rather than producing their own food via photosynthesis. Grass, algae, and phytoplankton are all autotrophs that rely on sunlight.