1. FEED ADDITIVES IN DIETS OF TRANSITION DAIRY COWS José Eduardo P
FEED ADDITIVES IN DIETS OF TRANSITION DAIRY COWS José Eduardo P. Santos Veterinary Medicine Teaching and Research Center School of Veterinary Medicine University of California - Davis

2. Objectives
Discuss the metabolic and endocrine effects of feed additives during the transition period
Potential impact of the use of feed additives during transition on performance and incidence of metabolic disorders in dairy cows

3. Rumen Fermentation Propionate CO2 + CH4 + CHO Protein Acetate +
Microbial
Protein + NH3
CO2 +
CH4 + H2
CHO
Protein
Pyruvate
Acetate +
Butyrate
Glucose

4. Effect of Ionophores on Rumen Bacteria (Gram +)
Extracellular Intracellular
ATP
H H+
ADP
H H+
K K+
Na Na+ M M

5. Results of Ionophore Use
Reduces Gram + population:
Proteolytic and amilolytic bacteria
Decreases proteolysis ----> Greater flow of nonammonia-nonmicrobial nitrogen to the duodenum
Reduces lactate producing bacteria: Streptococcus bovis and Lactobacillus spp.
Increases molar concentration of propionate
Reduces CH4 concentration ---> Less energy loss

6. Why Ionophores Would Benefit Transition Cows?
Improves efficiency of energy metabolism:
More propionate
More glucose
Less BHBA
More insulin
Less lipid mobilization
Lower incidence of subclinical ketosis
Reduces the risk for ruminal acidosis and bloat
Increases the flow of true protein (It may not change total protein flow because of the negative impact on microbial N)

9. 1.01
0.94
444/530
438/526
283/486
271/497

10. Gluconeogenic Precursors
4 major sources:
Propylene glycol
Calcium propionate
Sodium propionate
Glycerol
Poorly fermented in the rumen
Calcium propionate is also a source of Ca

16. Effect of Propylene Glycol on Liver Lipids and TG

17. Effect of PG on Transition Cow Performance
PG had no impact on milk composition and plasma insulin
PG increased IGF-I, plasma cholesterol and decreased MUN and NEFA
P > 0.15

19. - Niacin Adipose Tissue HSL Blood Compartment Niacin Triacylglycerol
Diacylglycerol
Monoacylglycerol
NEFA

24. Ruminally Protected Amino Acids
AA can be used as gluconeogenic precursors
Enhance oxidation of fatty acids by the hepatic tissue
Enhance VLDL synthesis and secretion
Reduce ketogenesis
Supply limiting amino acids for milk and milk protein synthesis

27. Bauchart et al. (1998) observed that rumen-protected lysine reduced hepatic triglyceride content
Review by Garthwaite et al. (1998) - 6 studies
Rumen protected Lys and/or Met supplemented pre- and postpartum
 DMI 0.5 kg/d,  milk yield 1.5 kg/d,  milk protein yield 79 g/d, and  milk fat yield 85 g/d
2 studies, supplemental Met was detrimental to performance

28. Yeast Culture
Possible reasons for feeding Saccharomyces cerevisiae in transition diets
Increase rumen pH (Selenomonas ruminatium)
Stimulate the growth of fiber digesting bacteria
Increase NDF digestibility
Reduce the depression in DMI immediately before calving
Improve DMI postpartum

30. Effect of Saccharomyces cerevisiae on transition cow performance (Robinson and Garrett,1999)
Feeding YC from d -28 to d 56 had no effect on DMI, DMI as % BW, BW and BCS changes, and NEL of diets during the pre- and postpartum periods
Feeding YC had no impact on concentration and yields of fat, protein, and lactose of primiparous and multiparous cows
P < .28
P < .09

31. Hypocalcemia (clinical or subclinical)
 Smooth Muscle Function
 Rumen and GI Tract Motility
 Uterine Motility-Immunity
 RP  Involution
 DA
 DMI
 NEB
 Metritis
 Ketosis
 Milk Production
 Fertility

32. Diet Intestine Vit. D ++ PTH/Vit D ++ Calcitonin  Hypercalcemia 
Bone Resorption
Diet
PTH/Vit D ++
Calcitonin 
Hypercalcemia 
Intestine
Vit. D ++
Extracellular Ca Pool
(8 to 10 g)
Plasma Ca Pool
2.5 to 3.0 g
PTH and
Vit D
Fecal Loss
g/d
Milk
g/d
Fetal Bone
g/d
Urinary Loss
g/d

33. Acidogenic Salts High chloride and sulfate salts
CaCl2, NH4Cl; MgCl, MgSO4, CaSO4, (NH4)2SO4
HCl
Acidify the blood by increasing H+ absorption
S is poorly absorbed --> It is not a good acidifier

34. -  H+ -  pH -  HCO3- - - Intracellular and Intravascular
Spaces
Lumen GI Tract
Cell Membrane -
SO4-2
 H+ -
 pH -
Cl-
 HCO3- - H+ -

35. Strategies for Prevention of Hypocalcemia
DCAD < 250 mEq/kg
DCAD > 250 mEq/kg
 Calcitropic
Hormones
 Passive
Absorption
 PTH Receptor
Sensitivity
Addition of Anions
Low Ca diets < 20 g/d
Vit. D Analogues
Ca Gels

38. Equations to Calculate DCAD
DCAD mEq/kg ={(0.38 Ca Mg + Na + K) - (Cl S P)}
(NRC’s coefficients)
DCAD mEq/kg ={(0.15 Ca Mg + Na + K) - (Cl S P)}
(Goff’s coefficients)
DCAD mEq/kg = {(Na + K) - (Cl + S)}
Assumes equal rate of absorption for all strong ions

39. How to Use Them
Step 1
Analyze all feed components for their mineral content
Na, K, S, Cl, Ca, P, and Mg
Select forages and ingredients with low K and Na content
Grain silages, low K alfalfa (mature), brewers grains, beet pulp without molasses, citrus pulp
Basal diet DCAD < 250 mEq/kg

40. Step 2: Adjust mineral content Provide Mg to achieve 0.4% diet DM
MgSO4, MgCl, MgO
Increase S up to 0.35 to 0.4 %
CaSO4
S > 0.4% may cause PEM and may interfere with Cu and Se
Keep P at 0.35 to 0.4%
High P intake (> 80g/d) may cause milk fever

41. Step 3: Acidify the diet Keep K as low as possible (K < 1.2%)
Keep Na as low as possible (Na < 0.15)
Increase Cl
CaCl2
Keep Cl < 0.8%, but high enough to lower urine pH
Adjust Ca content to 1.0 to 1.2%
Ca Propionate or CaCO3

42. Mineral Profile of a Close Up Diet
Dietary DCAD should be:
Multiparous cows = - 50 mEq/kg
Primiparous cows = 0 mEq/kg
Monitor urine pH
Urine pH should be between 5.8 and 6.8

44. Conclusions Ionophores (Monensin):
Prepartum: 30 ppm and Postpartum: ppm
PG and Ca Propionate may be used in the concentrate or as an oral drench. Consider Ca Prop. when using anionic salts
Niacin: Controversial results
Lipotropic agents and Yeast: Not recommended
Acidogenic salts: Highly recommended when hypocalcemia is a concern
RP AA: positive effects on milk protein content and yields of milk and milk protein when supplemented pre- and postpartum