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

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

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

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

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

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)

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

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

Effect of Propylene Glycol on Liver Lipids and TG

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

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

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

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

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

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

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

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 6 - 10 g/d Milk 20 - 80 g/d Fetal Bone 2 - 10 g/d Urinary Loss 0.25 - 1.0 g/d

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

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

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

Equations to Calculate DCAD DCAD mEq/kg ={(0.38 Ca + 0.3 Mg + Na + K) - (Cl + 0.6 S + 0.5 P)} (NRC’s coefficients) DCAD mEq/kg ={(0.15 Ca + 0.15 Mg + Na + K) - (Cl + 0.2 S + 0.3 P)} (Goff’s coefficients) DCAD mEq/kg = {(Na + K) - (Cl + S)} Assumes equal rate of absorption for all strong ions

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

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

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

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

Conclusions Ionophores (Monensin): Prepartum: 30 ppm and Postpartum: 10 - 15 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