Feed Additives Flashcards
Various nonnutritive substances added to a ration to:
-stimulate growth or other types of performance
-improvement of feed utilization of feed efficiency
-improving the health of the animal
Factors other than bio-efficacy considered relative to the use of an additive:
-cost
-toxicity
-tissue residues
Do feed additives produces their response in young, rapidly growing animals or mature animals?
young, rapidly growing animals
What are the two exceptions of additives that benefit mature animals?
-buffers
-thyroprotein compounds
Some feed additives have demonstrated ___________ responses and others demonstrated fairly ____________ responses
-situation-specific
-universal
Most common nonnutritive additives in common use:
-antibacterial agents
-hormones and their derivatives
-others (buffers, activated charcoal, antioxidants, bentonite, bloat-control compounds, methane inhibitors, enzymes, coccidiostats, B-agonists)
The two types of antibacterial agents:
-antibiotics
-sulfa drugs
Feed additive classifications
-medications
-antioxidant
-antifungal agents
-enzymes
-direct-fed microbials
-essential oils
-fermentation products
-herbs
-pellet binders
-surfactants
-pigments
-flavors
-stool conditioners
-buffers
Sub-therapeutic antibiotics action
antimicrobial
Sub-therapeutic antibiotics decreases:
-sub-clinical infections
-growth depressing microbial metabolites
-gut maintenance
-competition for nutrients
Organic acids action
antimicrobial (Gr-)
Plant extracts action
-varied physiological functions
-antimicrobial
-altered mucin production
-decreased intestinal “turnover”
Probiotics action
-specific pathogen exclusion
-immunological modulation
-improved nutrient use
-antimicrobial action (decrease pH and bacteriocins)
What are antimicrobial agents and anthelmintics defined as by the FDA?
drugs
What does the FDA regulate with antimicrobial agents?
-usage levels
-allowable combinations
-periods of withdraw prior to slaughter
Antibiotics
a compound synthesized by a living organism which inhibits the growth of another organism
What are antibiotics effective in?
-improving performance
-their ability to suppress or inhibit growth of certain microorganisms
Absorption of antibiotics
some are readily absorbed into the vascular system, others are hardly absorbed at all
General performance enhancement levels fed:
low levels of 5-50 g/ton
Disease prevention levels fed:
50-200 g/ton feed
Therapeutic levels fed:
200-500 g/ton
Therapeutic additives are used for:
-control of respiratory diseases
-diarrhea
-short-term treatment of the entire group of animals
Effects of antibiotic feeding
-reduced morbidity
-reduced incidence of secondary infections
-reduced incidence of dehydration and pneumonia
What happens to animals responding to antibiotic feeding?
-consume more feed than controls
-gain weight faster, so less food is needed per unit gain
Uses for antibiotics in cattle:
-best benefit to young stressed calves arriving to feedlot and cattle that has been mismanaged
-reduced the incidence of liver abscesses on high grain rations for feedlot cattle
Uses for antibiotics in sheep:
-used for finishing lambs
-used for feedlot lambs
Uses for antibiotics in dairy cows:
-does not increase milk production
-feeding high levels of antibiotics is prohibited by law because residue could carry into the milk
Antibiotics effects on the nutrition of animals must be __________
secondary, because they are drugs not nutrients
The metabolic affect of antibiotics:
the drug affects various enzyme systems such as oxidative phosphorylation reactions
The nutrient-sparing effect of antibiotics:
via altered microbial composition of the GI tract where the antibiotic may:
-stimulate microorganisms that favor nutrient synthesis of a critical nutrient
-suppression of organisms which compete with host for dietary needs
-improved nutrient absorption = thinner, healthier intestinal walls
Disease control of antibiotics:
benefits from suppression or control of subclinical or non-specific diseases
Societal concerns for antibiotics:
-have antibiotics become less effective from antibiotic resistant strains?
-does feeding antibiotics pose a public health threat?
Does feeding antibiotics pose a public health threat?
-antibiotic resistant strains of non-pathogenic bacteria with transferable resistant (R) factors emerge in the intestines of the animal being fed antibiotics
-R factors may be transferred to virulent bacteria in the animals
-Virulent, antibiotic-resistant bacteria a passed on to man
What is the difference in resistant bacteria in rural (works with animals) vs. city living?
nothing, failed to detect any differences
MGA
melengestrol acetate, a synthetic progestogen
What does MGA do when fed to feedlot heifers?
-suppresses estrus
-appears to promote growth (which may be due to water retention)
Synovex
S = 200 mg progesterone + 20 mg of estradiol benzoate
H = 200 mg testosterone + 20 mg of estradiol propionate
-sex specific
What does synovex do?
-increases of 10-15% in ADG
-savings in feed
Ralgro
-brand of zeranol
-acts like an estrogen
Zeranol
the active compound is resorcyclic acid lactone, a product isolated from a type of corn mold
-Ralgro is a brand of this
What does Ralgro do?
-acts like estrogen
-response is best with high quality rations (rations with an adequate supply of protein and energy)