1. Feeding Transition Cows
STEPANIE MILBURG LECTURE 12
2/23/2001

2. Goals of a Successful Feeding System
Understand the factors that will determine nutrient requirements
Deliver the needed nutrients to each cow to meet her requirements as economically as possible

3. Factors That Impact Nutrient Requirements
1. Milk Production Curve
2. Milk Fat and Milk Protein
3. Dry Matter Intake
4. Body Weight Loss and Gain

4. Phase Feeding Approach
Considers the various phases of lactation and gestation
Program is divided into periods based on milk production, milk fat percentage, feed intake, and body weight
Goal for the dry cow is to minimize metabolic disorders, increase longevity, increase profits of next lactation

5. Far off dry cows Begins at drying off time to 21 days before calving
Adapt the rumen microbes for higher energy diets fed postpartum
Prevent metabolic disorders
-force feed trace minerals/vitamins
-limit salt intake
-closely monitor calcium and phosphorus
Provide nutrients for rapidly growing calf

6. Close Up Dry Cows Starts 21 days prepartum
Nutritional management of macrominerals is important to enhance lactational and reproductive performance postpartum
One potential strategy for late gestation feeding is the dietary cation-anion difference (DCAD)

7. Dietary Cation-Anion Difference
Systemic acid/base balance of the cow
Feeding anionic diet increases H+ ions (creates acidosis). If cations are fed HCO3 is released (creates alkalosis)
Mild acidosis allows for greater absorption of Ca and P –very helpful to preparturient cows
Sources of anionic salts: CaSO4, NH3SO4, MgSO4, MgCl, NH3Cl, CaCl

8. DCAD Cont. DCAD = meq (Na +K) – (Cl+S)/ 100g DM
To calculate DACD the expression is: [%Na divided by .023) + (%K divided by .039)] – [(%Cl divided by .0355) + (%S divided by .016)]

9. Example Item Dietary Conc. (%) meq DCAD Na .10 .023 4.35K Cl S
DCAD = meq(Na +K) – (Cl+S) =

10. Common Metabolic Disorders

11. Rumen Acidosis
Excessively acid pH caused by greater fermentation and acid production by microbes than can be neutralized by the animal
Cause: Too much rapidly fermentable CHO (starch) and too little effective fiber
Feedlot cattle and early postpartum cows

12. Acidosis cont.. Acute : can cause death
Chronic or subclinical : decrease feed intake, fermentation efficiency
Prevention:
Avoid “slug” feeding
Balance starch/fiber fractions of diet
Allow for gradual adaptation to change

13. Ketosis
The excessive mobilization of body fat caused by an imbalance between glucose need and glucose supply that leads to a build up of ketones in the body
High demand for glucose (milk production or fetal growth) relative to supply (feed intake) leads to decreased glucose in blood and low insulin
Promote mobilization of long-chain fatty acids from adipose tissue

14. Ketosis cont.
The increase in ketone body concentration comes from beta-oxidation of long chain fatty acids in the liver
Ketone bodies = BHBA (beta-hydroxybutyrate), acetone, AcAc (acetoacetate)
Liver can oxidize 5 times as much fatty acid to obtain the same amount of ATP for energy

15. Ketosis cont.
As [AcAc] increases it spills into blood, urine, and milk – odor can be used as a diagnostic tool
Rarely fatal – production drops to decrease glucose demand
Administer glucose

16. Ketosis cont.. Prevention:
Avoid over fattening (Fat cows have poor appetites!)
Provide ample amounts of well-balanced diet (high energy)
Administer Niacin (reduces lipolysis)

17. Calcium Metabolism and Milk Fever
Calcium in the blood is critical to life and is strictly regulated!
Functions of Calcium:
1. Component of milk
2. Bone structure
3. Muscle Contraction
4. Nerve transmission

18. Hormonal Regulation of Calcium
Parathyroid hormone (PTH) – secreted by parathyroid glands in response to low blood Calcium
PTH increases blood calcium by:
- increase reabsorption of Ca in kidney
- increase reabsorption from bone
- increase activation of vitamin D

19. Hormonal regulation cont.
Calcitonin – Secreted by thyroid gland in response to elevated blood Ca
Decreases blood calcium by:
Increasing urinary Ca excretion
Decrease bone reabsorption

20. Milk Fever (Parturient paresis)
A decreased blood Ca in response to Ca drain of lactation
Feed intake drops at calving and the calcium-mobilizing system is inactive at calving
Blood Ca drops, PTH and vitamin D try to increase blood Ca
Target tissues are unable to respond to hormonal signals

21. Milk Fever cont. Symptoms:
decrease appetite and inactive digestive tract, “cold ears”, staggering, loss of balance, listlessness, coma, death
Treatment: Immediate I.V. infusion of Ca

22. Milk Fever cont. Prevention:
1. Feed diet low in Ca and P during dry period
2.Give Vitamin D at 2500 X requirement for 3-5 d before calving
3.Adjust anion-cation difference
-if anionic, get acidosis (acidosis favors Ca mobilization and PTH response

23. Summary
The transition cow’s nutrient needs can easily be neglected since she is no longer with the milking group
Careful consideration to her metabolic needs helps to ensure productivity and longevity in her next lactation