1st Law of Thermodynamics
= energy is not created nor destroyed Þ can be accounted for somewhere in the animals body.Unavailable
= (FE = fecal energy; UE = urinary energy; CH4)Useful
= workHeat
= Heat incrementDigestible energy = gross energy - FE
Metabolizable Energy
= GE-FE-UE (-GPD = CH4)Actual energy available to tissues for metabolism
Net Energy
= GE - FE - UE (-GPD = CH4) - HIActual energy used for work
NEM = maintenance
NEP = Production (growth, lactation, work (race, run, etc.), fiber production (wool, mohair, etc.), egg, fetus, etc.)
Energy Utilization:
1.
Digestion & Absorption of organic compounds containing covalent bonds2.
Excretion of energy containing compounds in feces & urine. Energy is not available to animal tissues3.
Metabolism of compounds that breaks the covalent bonds, transfers electrons and releases energy4.
Trapping of energy as ATP ® work5.
Produce heat ® inefficient meatbolism
Food Energy:
All energy we get is from foodOxidation of food releases free energy from chemical bonds
Oxidized to CO2 + H2O via enzymes
Oxidation:
loss of electrons from a compound (ie hydrogen).A compound is oxidized if reaction leads to an increase in O2 content and decrease in H content
Reduction:
Gain of electrons ( ie hydrogen).A compound is reduced if the reaction leads to an increase in H content & decrease in O2 content.
Redox State:
determines caloric density; more reduced = more caloric dense (more electrons [H] for transfer). Fats = 9, CHO = 4, Protein = 4. Fat is more reduced, not much O2. Oxygen is the terminal electron acceptor in the body - reduced to H2O.Electron Carriers:
transfer electron (H) in redox reactions. Known as coenzymes, serve as electron carriers.NAD =
Niacin, also NADP (phosphate group added)
Oxidized |
Reduced |
NAD |
NADH |
NADP |
NADPH |
FAD =
Riboflavin
Oxidized |
Reduced |
FAD |
FADH2 |
When released, electrons used for energy - ATP!! This is done through electron transport.
Adenosine Triphosphate
ATP -
produced as a result of oxidation, provides energy for muscle (contraction). Each phosphate group has 7.3 kcal:ATP
® ADP + Pi + 7.3 kcalADP
® AMP + Pi + 7.3 kcalNet reaction = ATP
® AMP + 2Pi + 14.6 kcalEnergy trapped & released
Transfer of energy in the body will be in phosphate bonds.
Creatine phosphate = 10.3 kcal
ATP = 7.3 kcal
Functions:
1.
muscle contraction - creatine phosphate + ADP « ATP + creatine2.
synthesis of new compounds - link AA together = protein (4 ATP/link)3.
transmission of nerve impulses4.
active absorption (in SI) heat production - via oxidation of foods (thermoregulation)