This document discusses various feed additives used in ruminant diets including antibiotics, ionophores, estrus suppressants, and buffers. It provides details on the mechanisms and effects of each type of additive as well as examples of commonly used additives such as monensin, melangesterol acetate, and growth promoting implants. The document aims to inform readers about the regulation and appropriate use of these additives in livestock and poultry feeds.

1. Feed Additives for
Ruminants
‫المجترات‬ ‫فى‬ ‫األعالف‬ ‫اضافات‬

2. ‫المجترات‬ ‫فى‬ ‫األعالف‬ ‫اضافات‬
1-‫المضادات‬‫الحيوية‬
2-‫األينوفور‬
3-‫مثبطات‬‫الشياع‬
4-‫اضافة‬‫أدوية‬‫لمعادلة‬‫الحموضة‬

3. Feed Additives
 Many commercially prepared additive
products are included in animal diets
 By definition, these products do not
supply nutrients
• Not listed in feed composition tables
 Since 1960, FDA has regulated feed
additive incorporation into animal
diets
• Prevention of cancer in human/animal

4. Feed Additives
 More than 1000 products are
approved by FDA for use in
livestock/poultry feeds
 Include products intended to
promote animal health
• Prevention/treatment of disease
• Growth promotion
• Both

5. Feed Additives
 Some additives can leave residues in
the muscle tissues
• Withdrawal times prior to slaughter
• Must choose correct additive for stage
of production

6. Feed Additives
 Antibiotics/Chemotherapeutics
 Ionophores
 Estrus suppressants
 Buffers

7. Antibiotics/Chemotherapeutics
 Against life or destructive to life
 Natural compound synthesized by living
organisms or chemically synthesized
compounds
 AB are either:
• Bacteriostatic
• Bactericidal
• or both

8. Antibiotics/Chemotherapeutics
 For over 50 years antibiotics and
chemotherapeutics have been used
in the animal feed industry
 Approximately 60% of beef cattle
and 75% of dairy cattle raised in
U.S. are estimated to have been fed
these at some point during
production

9. Antibiotics
 The primary reason to feed
antibiotics to ruminants is to control
liver abscesses, foot rot & secondary
infections/diseases as a result of
shipping stress

10. Antibiotics
 Control of liver abscesses is the
primary reason to continuously feed
antibiotics
• Cattle on high grain diets:
  episodes of acidosis =  liver
damage and infection
• The greater the severity of liver
abscesses, the greater the reduction in
growth performance

11. Common Antibiotics
 Chlortetracycline
• Aureomycin
• Numerous recommendations based on
production level of animal
 48 hour withdrawal time
 Oxytetracyline
• Terramycin
• 75 mg/hd/d =  liver abscesses
• 0.5 - 2.0 g/hd/d =  shipping fever complex
 Feed 3 - 5 days before & after arrival
 7 day withdrawal time

12. Common Antibiotics
 Tylosin
• Tylan
• 8 - 10 g/t or 60 - 90 mg/hd/d
• Cleared for use with Rumensin and/or
MGA
• Feed to reduce incidence of liver
abscesses

13. Ionophores
 Results in selection of certain
microorganisms in the rumen
• Inhibits or depresses certain microbe
growth
• Alters rumen fermentation
 Usually  propionate production

14. Ionophores
 Mechanism of action: Disrupts the
[ion] gradient across the cell
membrane = cell death
• Destroys secondary transport processes
and energy-conserving reactions

15. Effects of Ionophores
1.Improve efficiency of energy metabolism
by changing the VFA profile &  energy lost in
fermentation
•  energy retention
2.Decrease breakdown of feed protein & may
decrease microbial protein synthesis
• Impacts: Growing cattle on high-roughage diets
3.Reduce digestive upsets = reduced stress =
improved animal performance

16. Ionophores
 Too high of a level of ionophore can
reduce cellulolytic bacteria
•  fiber digestion
•  rumen protein = ruminal protein
shortage

17. Ionophores
 Growing cattle: high-roughage diets
• Improved daily gain (5 - 15%) & feed
efficiency (8 - 12%)
 Finishing cattle: high-concentrate diets
• Improved feed efficiency (6 - 8%) and subtle
improvement in daily gain (1 - 3%)
• Prevention or control of bloat and acidosis

18. Common Ionophores
 Rumensin (Monensin Sodium)
• 20 - 30 g/ton
 Bovatec (Lasalocid Sodium)
• 10 - 30 g/ton
• 1 mg/2.2 lb. of BW = control of coccidiosis
 Cattlyst (Laidlomycin Propionate
Potassium)
• 5 - 10 g/ton

19. Estrus Suppressants
 Melengesterol Acetate (MGA)
• Synthetic hormone similar in structure
and activity to progesterone
• Breeding females:
 Used to synchronize females for breeding

20. Estrus Suppressants
 Melengesterol Acetate (MGA)
• Feedlot heifers:
 Suppress estrus =  growth performance
• +3 - 7% for ADG & FE
•  injury,  dark cutters,  energy
expended by chasing heifers
• 0.25 - 0.50 mg/hd/d
 Cleared for use with Rumensin, Bovatec &
Tylan
 48 hour withdrawal period

21. Buffers
 Added to the diet to aid in resisting
pH changes of the rumen when acids
are present
• Reduces incidence of acidosis on high
grain diets
• Improves fiber digestion in corn silage
diets
 Performance is variable
• -2 - 5% improvement in ADG & FE

22. Buffers
 Sources:
• Sodium Bicarbonate: 0.75 - 1.5% diet DM
• Limestone: 1.0% diet DM
• Sodium Bentonite: 1 - 2% diet DM
• Magnesium oxide: 0.5 - 0.75% diet DM

23. Growth Promotants
 Redirection of nutrients from fat
deposition to lean tissue deposition.
•  Growth hormone secretion
•  steroidal effect on growth of skeletal
muscles through  [IGF’s]

24. Growth Promotants
 Given to cattle to improve:
• Feed Efficiency:+15 - 25% in growing cattle
+10 - 12% in finishing cattle
• Daily Gain:+.33 lb./d in growing cattle
+10 - 15% in finishing cattle
• 4 - 16% improvement in DMI

25. Growth Promotants
  cost of gain,  % choice carcasses
(25%),  % lean
 Estradiol implants reduce NEg
requirement by 5%
• E2 implants = 18 - 20% NEg requirement
reduction
 Most implants are effective from 70 to
100 days

26. Growth Promotants
 Most are cleared for use in
confinement cattle and some are
available for grazing cattle
 There are 6 individual component
implants & 10 combination implants
currently on the market
• Implant wars = changing companies and
products

27. Common Growth Promotants
 Estrogens
• Estradiol 17
• Estradiol Benzoate (71% E17)
• Zeranol (produced from the production
of mold)
 Androgens
• Testosterone Propionate
• Trenbolone Acetate (TBA)

28. Common Growth Promotants
 Progestins
• Progesterone
• Melengesterol Acetate (MGA)
 Somatotropins (growth hormones)
• Bovine Somatotropin (BST)