Strategies to manage hypocalcemia in dairy cattle · Strategies to manage hypocalcemia in dairy...
Transcript of Strategies to manage hypocalcemia in dairy cattle · Strategies to manage hypocalcemia in dairy...
12/7/2018
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Strategies to manage hypocalcemia in dairy cattle
Thomas R. Overton, Ph.D.
Professor of Dairy Management
Director, PRO-DAIRY program
Associate Director, Cornell Cooperative Extension
Cornell University, Ithaca NY
Do we need to worry about subclinical hypocalcemia if milk fever rates are low?
1 to 3%
40 to 80%
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Calcium status during the transition period
5.5
6.5
7.5
8.5
9.5
10.5
-18 -13 -8 -3 2 7 12
Pla
sma T
ota
l Calc
ium
(m
g/dL)
Day Relative to Calving
Sweeney et al., 2015. J. Dairy Sci 98 (Suppl. 2):128.
Subclinical hypocalcemia risks
• Impaired health• Metritis (Martinez et al., 2012)
• DA (Chapinal et al., 2011)
• Mastitis (Curtis et al., 1983)
• Subclinical and clinical ketosis (Curtis et al., 1983; Ribeiro et al., 2011)
• Immune function (Kimura et al., 2002; Martinez et al., 2012)
• Decreased milk production (Chapinal et al., 2012)
• Poorer reproductive performance• Reduced pregnancy rate (Martinez et al., 2012)
• Reduced pregnancy to first service (Chapinal et al., 2012)
• Longer interval to pregnancy (Martinez et al., 2012)
• Chronic subclinical hypocalcemia: increased disease frequency and increased time to pregnancy (Caixeta et al., 2017)
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Acknowledgment – Dr. Jessica McArt, Cornell U.
Classification of SCH at calving
• Objective: to determine the association of plasma total calcium (tCa) collected soon after parturition with:• Health outcomes (RP, metritis, DA, clinical mastitis)
• Culling risk within 60 DIM
• Pregnancy risk to 1st service
• Milk production across the first 9 DHIA tests
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Materials and methods
• Prospective cohort study in 5 dairy herds in NY• Part of a large randomized clinical trial
• Control cows only
• Enrolled cows that calved between February-November, 2015
Farm
A B C D E
Milking cows, n 1,474 567 1,282 1,677 1,222
Milk production, kg 38.4 38.9 37.0 37.3 36.8
Prepartum DCAD, mEq/100 g DM -6.9 -2.8 -5.5 7.3/14.1 -2.8
Results
• n = 1,416 included in the final analysis• Primiparous, n = 350
• Multiparous, n = 1,066
• Mean time from calving to blood collection = 3 h
Primiparous Multiparous
Retained placenta 6.0% 9.2%
Metritis 13.0% 8.9%
Displaced abomasum 0.3% 3.7%
Clinical mastitis 4.6% 10.0%
Culling 2.6% 4.9%
Pregnancy to 1st service 44.5% 37.3%
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Results
• Primiparous cows: tCa at calving meant nothing!
• Multiparous cows:• tCa not associated with: risk of RP, metritis, clinical mastitis,
or pregnancy to 1st service
• tCa ≤1.85 mmol/L: • More likely to develop a DA
• RR = 2.8 (95% CI = 1.35 to 5.85; P = 0.006)
• Higher Ca associated with increased culling risk• Every 0.1 mmol/L increase, RR = 3.4 (95% CI = 0.95 to 12.0; P = 0.06)
Results
• Multiparous cows with tCa ≤1.95 mmol/L: • Made more milk: 42.9 vs. 41.8 kg per test-day, P < 0.001
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• 2 dairy herds in NY
• 389 Holstein cows• Primiparous, n = 186
• Multiparous, n = 253
• Blood collected daily for first 4 days of lactation
• Metritis, DA, milk production for 15 wk
Temporal association of [Ca] with disease and milk production
• Objectives:• Determine which DIM has the best association with
negative outcomes
• Determine optimal [Ca] cut points for these days
• Modeled primiparous and multiparous separately
• Plasma [Ca] assessed in continuous scale
• If [Ca] meaningful, created an optimal threshold using ROC curves
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Findings: primiparous cows
• Reduced [Ca] associated with increased risk of metritis at 2, 3, 4 DIM (P < 0.001)
• Reduced [Ca] at 1 DIM associated with higher milk production, P = 0.01• Cut point = 2.15 mmol/L, 2.9 ± 0.80 kg/d
• AUC = 0.57, Se = 57.8%, Sp = 55.0%
DIM AUC
Cut point
(mmol/L) Se Sp
cows below
cut point (%) RR (95% CI)
2 0.78 ≤2.15 72.2 68.6 36.8 4.0 (2.0-8.1)
3 0.80 ≤2.10 70.6 79.7 26.7 5.2 (2.7-10.3)
4 0.80 ≤2.15 71.4 79.1 26.4 6.1 (3.0-12.3)
Findings: multiparous cows
• Difference based on parity for disease outcome
• Decreased [Ca] associated with increased risk of metritis and/or DA at:• 2 DIM for parity 2
• 4 DIM for parity ≥3
Parity DIM P-value AUC
Cut point
(mmol/L) Se Sp
cows below
cut point (%) RR (95% CI)
2
2 0.04 0.67 ≤1.97 44.4 88.8 14.3 3.9 (1.6-9.8)
3 0.23 ─ ─ ─ ─ ─ -
4 0.22 ─ ─ ─ ─ ─ -
3
2 0.88 ─ ─ ─ ─ ─ -
3 0.58 ─ ─ ─ ─ ─ -
4 0.03 0.70 ≤2.20 72.7 60.5 44.4 3.6 (1.5-5.8)
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• [Ca] associated with milk production at 1 and 4 DIM
• Direction of association dependent on DIM
• 1 DIM: lower [Ca] associated with increased milk production • 2.88 ± 0.84 kg/d, P < 0.001
• Cut point = 1.77 mmol/L, AUC = 0.60
• 4 DIM: lower [Ca] associated with decreased milk production • - 1.80 ± kg/d, P = 0.02
• Cut point = 2.20 mmol/L, AUC = 0.52
Findings: multiparous cows
Blood calcium regulation
PARATHYROID GLAND
PTH secretion
KIDNEY
Activation of Vitamin D
Calcium excretion
INTESTINE
Ca absorption
BONE
Release of Ca
Low blood
calcium
Active Vitamin D+
++
PTH
PTH
Modified slide from B. M. Leno; Goff et al., 2008
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Potential strategies to improve Ca status and postpartum health, performance, and reproduction
• Calcium administration at or after calving as treatment/prophylaxis
• Ration formulation strategies for prepartum (close-up) ration
Postcalving Ca treatment/prophylaxis options
• Intravenous Calcium• Rapid supply of available calcium
• Appropriate for clinical milk fever
• Unnecessary for cows with no clinical signs
• Oral calcium boluses or drenches• Will not provide Ca quickly enough for recumbent cow
• Slow release of different calcium salts or other compounds
• May be more appropriate for suspected subclinical cases
• Subcutaneous calcium• Intermediate to the above two options
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Serum total Ca following postpartum prophylactic administration of Ca-IV (500 ml 23% Ca borogluconate) or Ca-Oral (2 Ca boluses 12-h apart). From Blanc et al., 2014. J. Dairy Sci. 97:6901–6906
Targeted Ca bolus supplementation can improve postpartum outcomes
Oral Ca bolus supplementation:
• Beneficial for:• Multiparous cows calving with BCS > 3.5, lame cows (locomotion score 3 or 4 prior to calving),
primiparous cows calving at >712 d old, and cows with parity ≥3 (fewer health disorders)
• Multiparous cows with high previous lactation mature equivalent milk yield and primiparous cows calving with BCS > 3.5 (increased milk yield)
• Multiparous cows (reduced services per conception)
• Detrimental for: • Multiparous cows with lower previous lactation mature equivalent milk yield (reduced milk
yield)
• Primiparous cows (increased services per conception)
Questionable benefits to a “blanket” treatment approach
Oetzel and Miller, 2012; Martinez et al., 2016; Leno et al., 2018
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Miltenburg et al., 2016. J. Dairy Sci. 99:6550–6562
• 984 cows on 7 commercial farms w/o visible milk fever
• Administered Ca SQ immediately postcalving and at 12 to 24 h postcalving• Ca gluconate in combination with Ca glucoheptonate
• Total ~ 10 g of supplemental Ca
• Results• Transient increase in blood Ca at 24 h
• Treated cows slightly less likely to receive subsequent Ca treatments (5.0 vs. 8.4%)
• No effect on retained placenta, metritis, hyperketonemia, prevalence of purulent vaginal discharge, culling from the herd, early lactation production, probability of pregnancy to first artificial insemination, or time to pregnancy.
Amanlou et al., 2016. J. Dairy Sci. 99:9199-9210.
• 375 cows on commercial dairy in Iran without milk fever or evidence of other disorders at calving
• Treatments:• no s.c. infusion of Ca (control; n = 190)• 1 s.c.infusion of 250 mL of 40% Ca borogluconate (1SC250; n = 72; 7.6 g of Ca) at calving• 1 s.c. infusion of 500 mL of 40% Ca borogluconate (1SC500; n = 63; 15.2 g of Ca) at calving• 2 s.c. infusion of 250 mL of 40% Ca borogluconate, one immediately after calving and the
second 12 to 18 h after first administration (2SC250; n = 50; 15.2 g of Ca).
• Results• Increased serum Ca during wk 1 for cows administered Ca• Increased DMI first 24 h postcalving for cows administered Ca• Greater risk for metritis and endometritis for controls
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Prepartum dietary management is only way to prevent postpartum hypocalcemia
• Manipulate dietary cation anion difference (DCAD)• Minimize/avoid high potassium forages (legumes)
• Supplement anions (chloride and/or sulfur containing supplements)
• Actualize a low calcium diet through use of a binder of calcium in the diet to decrease absorption• Synthetic Zeolite A
Improving Ca status via altering prepartum Dietary Cation-Anion Difference (DCAD)
• Impact on calcium metabolism:• Improved sensitivity of PTH receptor to PTH stimulation
• Decreased urine pH increases urinary Ca excretion = increased calcium flux
• Systemic pH reduction may directly stimulate Ca resorption from bone
Cations:Sodium (+1)Potassium (+1)
Anions:Chloride (-1) Sulfate (-2)
More H+ in blood to maintain electroneutrality
Decreased blood pHIncreased H+ excretion
Goff et al., 2008. Vet J. 176:50–57.
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Major strategies for application of DCAD for close-up dry cows
• Focus on feeding low K (and Na) forages and feeds to close-up dry cows• Calculated DCAD ~ +10 mEq/100 g of DM
• Urine pH ~ 8.3 to 8.5
• Feeding low K forages along with partial use of anionic supplement in close-up ration or one-group dry cow ration
• Calculated DCAD ~ 0 mEq/100 g of DM
• Urine pH ~ 7.5
• Feeding low K forages along with full use of anionic supplement in close-up ration or one-group dry cow ration
• Calculated DCAD ~ -10 to -15 mEq/100 g of DM
• Urine pH ~ 5.5 to 6.0 – need to monitor weekly and adjust DCAD supplementation if out of range
• Need to also supplement Mg (dietary target ~ 0.45%) during close-up
• Recommend supplementing Ca (0.9 to 1.0% if low K only; 1.4 to 1.5% if full anionic diet)
Day -31 to Day -25 Day -24 to Day 0 Day 0 to Day 63
Low K control+10 mEq/100 g diet DM
Lactating Ration
Medium DCAD-3 mEq/100 g diet DM
Low DCAD-18 mEq/100 g diet DM
Low K control+18.3 mEq/100 g diet DM
Low K control+18.3 mEq/100 g diet DM
Medium DCAD+5.9 mEq/100 g diet DM
Low DCAD-7.4 mEq/100 g diet DM
Leno et al., 2017. J. Dairy Sci. 100:4604–4622.
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Prepartum Diets, lbs DM; Leno et al., 2017
100:4604–4622.
Ingredient (lbs DM/d) Control MedDCAD LowDCAD
BMR Corn Silage 12.77 12.77 12.77
Wheat Straw 8.00 8.00 8.00
Amino Plus 2.30 2.30 2.30
Citrus Pulp 0.95 0.95 0.95
Soybean Hulls 0.66 0.66 0.66
Canola Meal 0.63 0.63 0.63
Molasses 0.19 0.19 0.19
Calcium diphosphate 0.13 0.13 0.13
Ground corn grain 0.12 0.12 0.12
Salt 0.07 0.07 0.07
Vitamin Mix 0.04 0.04 0.04
Rumensin (mg) 318 318 318
Animate - 0.56 1.14
Wheat Midds 0.92 0.74 0.55
Calcium carbonate 0.82 0.80 0.77
Corn Distillers Ethanol 0.63 0.37 0.11
Magnesium Oxide 0.16 0.12 0.07
Urea 0.12 0.06 -
CON MedDCAD LowDCAD LactatingDM (%) 46.3 ± 1.6 46.5 ± 1.3 46.4 ± 1.1 45.7 ± 1.8CP (% DM) 13.0 ± 0.3 13.2 ± 0.4 13.2 ± 0.5 15.7 ± 0.2ADF (% DM) 30.2 ± 0.7 30.5 ± 1.3 30.1 ± 1.3 20.6 ± 0.8NDF (% DM) 44.3 ± 1.2 44.0 ± 2.1 43.2 ± 1.8 31.1 ± 1.0Starch (% DM) 17.0 ± 0.5 16.0 ± 0.8 16.3 ± 0.9 26.0 ± 0.7NFC (% DM) 33.6 ± 0.9 34.3 ± 2.5 35.0 ± 1.9 45.8 ± 1.2Fat (% DM) 1.1 ± 0.1 1.3 ± 0.2 1.1 ± 0.3 2.3 ± 0.2Ca (% DM) 1.54 ± 0.12 1.57 ± 0.14 1.57 ± 0.07 0.95 ± 0.03P (% DM) 0.44 ± 0.01 0.43 ± 0.01 0.41 ± 0.01 0.41 ± 0.02Mg (% DM) 0.47 ± 0.01 0.48 ± 0.03 0.50 ± 0.03 0.44 ± 0.02K (% DM) 1.28 ± 0.07 1.26 ± 0.06 1.24 ± 0.07 1.37 ± 0.05S (% DM) 0.20 ± 0.01 0.30 ± 0.02 0.41 ± 0.02 0.29 ± 0.01Na (% DM) 0.13 ± 0.01 0.13 ± 0.01 0.14 ± 0.01 0.44 ± 0.02Cl (% DM) 0.27 ± 0.03 0.47 ± 0.05 0.69 ± 0.04 0.40 ± 0.02DCAD (mEq/100g DM) 18.3 ± 0.8 5.9 ± 3.4 -7.4 ± 3.6 25.0 ± 1.5Predicted MP (g/kg DM) 93.8 93.23 92.26 116.56
Analyzed (mean +/- SD) composition of experimental diets
Leno et al., 2017. J. Dairy Sci. 100:4604–4622.
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* * * * * * * * * * * *
0
1
2
3
4
5
6
7
8
9
-23 -21 -19 -17 -15 -13 -11 -9 -7 -5 -3 -1
Uri
ne
pH
Day Relative to Calving
Urine pH
Control
MedDCAD
LowDCAD
Quadratic P<.0001Trt P<0.0001
Wk P=0.30TrtxWk P=0.02
Leno et al., 2017. J. Dairy Sci. 100:4604–4622.
8.2
8.4
8.6
8.8
9
9.2
9.4
2nd 3rd+
Blo
od
Cal
ciu
m (
mg
/dL)
Parity Group
Postpartum Blood Calcium Treatment by Parity Interaction
Control
MedDCAD
LowDCAD
TrtxParity P=0.06
*
Leno et al., 2017. J. Dairy Sci. 100:4604–4622.
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Dry Matter Intake
Prepartum Diet P-values
CON Med Low SEM Linear Quad Trt×Wk
Prepartum
DMI, kg/d 14.55 15.08 14.08 0.23 0.15 0.007 0.45
DMI, % of BW 1.87 1.89 1.80 0.03 0.16 0.22 0.38
Postpartum (wk 1 to 3)
DMI, kg/d 20.99 21.74 22.30 0.50 0.07 0.88 0.24
DMI, % of BW 2.94 3.04 3.15 0.07 0.03 0.99 0.37
Leno et al., 2017. J. Dairy Sci. 100:4604–4622.
Milk Production: Weeks 1 to 3
Prepartum Diet P-values
CON Med Low SEM Linear Quad Trt×Wk
Milk yield, kg/d 40.54 42.13 43.79 1.05 0.03 0.97 0.35
Fat, % 4.38 4.36 4.24 0.08 0.21 0.63 0.10
True protein, % 3.54 3.49 3.27 0.07 0.005 0.33 0.36
Lactose, % 4.64 4.67 4.69 0.03 0.25 0.94 0.38
Total Solids, % 13.63 13.61 13.27 0.10 0.01 0.20 0.10
ECM, kg/d 46.12 48.04 49.50 1.35 0.08 0.89 0.39
MUN, mg/dL 10.32 9.72 9.44 0.30 0.04 0.67 0.17
SCS 2.62 3.26 2.73 0.25 0.75 0.06 0.27
Leno et al., 2017. J. Dairy Sci. 100:4604–4622.
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Summary considerations for effective DCAD
diet implementation
• Account for macrominerals in forages (wet chemistry)
• CONSISTENCY in forages/feeds/mixing is key
• Prevent sorting of ration
• Particle size of TMR and moisture
• Sources:
• Commercial products best (palatability)
• Some sources poor palatability (Ca chloride, ammonium chloride)
• Make sure you supplement Mg (Mg oxide, Mg sulfate, commercial Mg sources)
• Use urine pH monitoring to gauge implementation
• Urine pH 6 to 7 has been general recommendation
• With excellent management, can target urine pH 5.5 to 6
• Target CV < 8% (12 to 15 cows; 4 to 6 h postfeeding if possible)
Low Prepartum Calcium Feeding
• Feeding Ca below requirement prepartum can stimulate Ca homeostasis prior to calving, preparing for Ca challenge
• Calcium must be less than ~20 g/d absorbed• Practically this is very difficult based on feeds and forages used
• Alternatively, calcium binding compounds can be fed to create a “functionally” deficient Ca diet
Shappell et al, 1987
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• Marketed in Europe and Canada –recently entered U.S. market
Grabher et al., 2009, Thilsing-Hansen et al., 2001
Feeding calcium binders prepartum improves blood Ca status at calving
Sodium aluminum silicate (Zeolite A)
• Capable of binding to dietary Ca, P, and Mg (Thilsing et al., 2006)
• Shown to increase active form of vitamin D prepartum and improve calcium status (Thilsing-Hansen et al., 2002; Pallesen et al., 2008)
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Synthetic Zeolite A fed during the prepartum period as a Ca binder
• Objective: To determine the effect of feeding sodium aluminum silicate to multiparous Holstein cows during the prepartum period on serum mineral status, dry matter intake, postpartum performance, and oxidative status
• Enrolled 60 multiparous Holstein cows
• 5 cows removed; 3 calved with twins/calved early, 1 had a DA prepartum, 1 diagnosed with toxic mastitis
• 2nd lactation: n=24, ≥3rd lactation: n=31
• Cows enrolled 28 d prior to expected calving and randomly assigned to one of two dietary treatments starting 21 d prior to expected calving
• Control (CON; n=29) - Contains 40% CS, 33% wheat straw, and 27% concentrate
• Experiment (EXP; n=26) - CON diet with the addition of a proprietary sodium aluminum silicate product – X-Zelit, Proteckta, Lucknow, Ontario, CA/Vitfoss, Graasten, DK) at 3.3% of DM, targeting 500 g/d as fed.
• Cows fed same postpartum ration
Kerwin et al., 2018
Chemical composition of diets
Prepartum Postpartum
Nutrient CON EXP Fresh
CP, % DM 13.6 ± 1.0 13.5 ± 0.7 16.4 ± 0.4
aNDF, % DM 46.4 ± 1.4 46.0 ± 1.7 30.6 ± 2.8
Starch, % DM 16.8 ± 1.7 16.3 ± 0.3 26.1 ± 1.6
Sugar, % DM 3.2 ± 0.8 3.3 ± 0.4 3.3 ± 0.5
Crude fat, % DM 2.24 ± 0.13 2.25 ± 0.30 2.64 ± 0.24
Ash, % DM 6.12 ± 0.53 7.99 ± 0.36 9.14 ± 0.49
Ca, % DM 0.68 ± 0.05 0.65 ± 0.03 1.00 ± 0.07
P, % DM 0.39 ± 0.03 0.38 ± 0.02 0.38 ± 0.01
Mg, % DM 0.42 ± 0.05 0.42 ± 0.03 0.51 ± 0.04
K, % DM 1.14 ± 0.06 1.12 ± 0.04 1.91 ± 0.11
S, % DM 0.25 ± 0.00 0.24 ± 0.01 0.46 ± 0.04
Na, % DM 0.14 ± 0.03 0.50 ± 0.04 0.82 ± 0.04
Cl, % DM 0.31 ± 0.03 0.30 ± 0.03 0.53 ± 0.03
DCAD, mEq/100g +11.0 ± 2.1 +26.9 ± 1.7 +40.8 ± 2.5 Kerwin et al., 2018
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Calcium
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
-17 -10 -5 -3 -1 0 0.25 0.75 2 3 4 6 7 10 15
Ca (
mg/dL)
Day Relative to Calving
CON
EXP
**
**
**
Prepartum effects
Trt P < 0.0001
Day P = 0.0002
Trt x day P = 0.05:
Postpartum effects:
Trt P < 0.0001
Day P < 0.0001
Trt x day P = 0.0006
Kerwin et al., 2018
Phosphorus
0
1
2
3
4
5
6
7
8
-17 -10 -5 -3 -1 0 0.25 0.75 2 3 4 6 7 10 15
P (
mg/dL)
Day Relative to Calving
CON EXP
***
*****
*
Prepartum effects:
Trt P < 0.0001
Day P < 0.0001
Trt x day P = 0.04
Postpartum effects:
Trt P = 0.0006
Day P < 0.0001
Trt x day P < 0.0001
Kerwin et al., 2018
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SCH prevalence
0
10
20
30
40
50
60
70
80
90
100
-17 -10 -5 -3 -1 0.25 0.75 2 3 4 6 7 10 15
Perc
ent
of
cow
s w
ith s
eru
m
Ca <
8.5
mg/dL
Day relative to calving
CON
EXP
*
*
*
*
*
*
†*
Kerwin et al., 2018
Chronic SCH prevalence
0%
10%
20%
30%
40%
50%
60%
0 1 2 3 4
Perc
ent
of
cow
s per
treatm
ent
# of Samples < 8.5 mg/dL through 3 DIM
CON
EXP
P < 0.0001
Kerwin et al., 2018
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Prepartum outcomes
Treatment P-value
Variable CON EXP SEM Trt Trt x Week
DMI (kg/d) 14.6 14.0 0.2 0.07 0.04
DMI (% of BW) 1.82 1.79 0.03 0.44 0.10
EBAL (Mcal/d) 5.4 4.4 0.4 0.05 0.11
BW (kg) 808 790 4 0.0004 0.02
BW change (kg) 17 6 4 0.04 ―
BCS 3.37 3.29 0.02 0.008 0.32
Kerwin et al., 2018
Postpartum outcomes
Treatment P-value
Variable CON EXP SEM Trt Trt x Week
DMI (kg/d) 21.7 22.2 0.4 0.51 0.16
DMI (% of BW) 3.09 3.16 0.06 0.36 0.20
EBAL (Mcal/d) -11.8 -11.9 0.7 0.91 0.66
BW (kg) 713 708 5 0.42 0.82
BW change (kg) -36 -36 7 0.96 ―
BCS 3.14 3.11 0.03 0.34 0.01
Kerwin et al., 2018
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Milk Composition weeks 1-4Treatment P-value
Variable CON EXP SEM Trt Trt x Week
Milk Yield (kg/d)
Week 1 – 4 48.0 47.5 0.7 0.58 0.99
Week 1 - 9 51.7 50.7 0.7 0.37 0.84
Fat (%) 4.17 4.32 0.08 0.17 0.05
Fat (kg/d) 1.98 2.03 0.04 0.35 0.26
Protein (%) 3.19 3.30 0.05 0.09 0.24
Protein (kg/d) 1.51 1.55 0.03 0.33 0.88
Lactose (%) 4.58 4.59 0.02 0.78 0.59
Lactose (kg/d) 2.22 2.20 0.04 0.67 0.54
TS (%) 13.03 13.32 0.11 0.07 0.18
TS (kg/d) 6.23 6.30 0.10 0.65 0.66
ECM (kg/d) 53.0 53.8 0.9 0.50 0.57
ECM/DMI 2.47 2.47 0.05 0.95 0.47
MUN (mg/dL) 12.46 10.90 0.43 0.01 0.87
SCS 1.07 1.08 0.25 0.98 0.72
Kerwin et al., 2018
Energy Corrected Milk Yield weeks 1-4
46
48
50
52
54
56
58
1 2 3 4
ECM
(kg)
Week relative to calving
Con
ExpWeek 1 – 4 effects:
Trt P = 0.50
Week P = 0.04
Trt x week P = 0.57
Kerwin et al., 2018
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Colostrum
0
1
2
3
4
5
6
7
8
9
Colo
stru
m y
ield
(kg)
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
IgG
(m
g/dL)
P = 0.16 P = 0.29
0
100
200
300
400
500
600
IgG
yie
ld (
g)
CON
EXP
P = 0.35
Oxidative Stress
Treatment P-value
Variable CON EXP T T × D
Prepartum
AOP 44.80 ± 1.93 42.49 ± 2.11 0.42 0.68
RONS 69.51 (66.23-72.94) 69.25 (65.73-72.96) 0.92 0.90
OSi 1.70 (1.54–1.89) 1.78 (1.60-1.99) 0.54 0.81
Postpartum
AOP 42.81 ± 1.63 42.45 ± 1.76 0.88 0.35
RONS 49.15 (45.61-52.96) 50.14 (46.35-54.25) 0.71 0.18
OSi 1.24 (1.12-1.37) 1.28 (1.15-1.42) 0.66 0.76
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Time to pregnancy by treatment
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
Surv
ival
Pro
babilit
y
(pro
port
ion n
onpre
gnant)
DIM
CON EXPP = 0.17
70 days 89 days
Kerwin et al., 2018
Overall summary
• Management of subclinical hypocalcemia in postcalving cows is important for health, milk yield, and reproduction, even when clinical issues are not present
• Calcium treatment/prophylaxis is beneficial only in selected higher risk subgroups of cows – blanket treatment approaches generally do not result in overall responses in health, production, or reproduction
• Prepartum nutritional management is the only way to robustly improve subclinical hypocalcemia
• Managing the dietary cation-anion difference through use of anionic supplements improves blood calcium along with postpartum intake and performance
• As an alternative to DCAD management, actualizing the low calcium diet approach through use of a dietary binder of calcium prepartum substantially improved blood calcium postcalving – trends toward positive effects on reproductive performance warrant further study