Case Study: Evaluation of Calcium Propionate and Propylene Glycol Administered into the Esophagus of Dairy Cattle at Calving1

Abstract

A field study was conducted to evaluate the effects of oral drenching with additional energy or energy plus calcium on blood parameters and performance of fresh cows. Treatments were 9.5 L water (control), 9.5 L water plus 300 mL (310 g) propylene glycol (PG), or 9.5 L water plus 0.68 kg calcium propionate (CP). Cows received the assigned drench within 4 h of calving and again 24 h post-calving. Animals were bled prior to each drench and on d 4 and 10 of lactation. Animals were fed and managed by parity (primiparous vs multiparous) in a commercial setting. Health events were recorded during calving and for the first 15 d in milk (DIM). Milk records were evaluated from monthly test weights the first 4 mo in lactation. The addition of PG or CP did not affect either plasma calcium or glucose (P>0.05). Plasma nonesterified fatty acid levels were lower in animals receiving the PG drench as compared with animals receiving either the control or CP treatment (P<0.05). Plasma β-hydroxybutyrate was lowest at calving but was not affected by treatment. Health disorders (retained placenta, ketosis, hypocalcemia, displaced abomasum, metritis) were low across all treatment groups. Cattle receiving either PG or CP at calving had a significantly lower incidence of metritis compared with control animals (P<0.05). Averaged across all trial periods, animals receiving PG had 3.1 kg/d greater milk production than those receiving the control drench (P<0.05).

Full text

115
CASE STUDY: Oral Drenching with Calcium or Energy at Calving
The Professional Animal Scientist 17:115–122
Abstract
A field study was conducted to
evaluate the effects of oral drenching
with additional energy or energy plus
calcium on blood parameters and
performance of fresh cows. Treatments
were 9.5 L water (control), 9.5 L water
plus 300 mL (310 g) propylene glycol
(PG), or 9.5 L water plus 0.68 kg
calcium propionate (CP). Cows received
the assigned drench within 4 h of calving
and again 24 h post-calving. Animals
were bled prior to each drench and on d
4 and 10 of lactation. Animals were fed
and managed by parity (primiparous vs
multiparous) in a commercial setting.
Health events were recorded during
calving and for the first 15 d in milk
(DIM). Milk records were evaluated
from monthly test weights the first 4 mo
in lactation. The addition of PG or CP
did not affect either plasma calcium or
glucose (P>0.05). Plasma nonesterified
fatty acid levels were lower in animals
receiving the PG drench as compared
with animals receiving either the control
or CP treatment (P<0.05). Plasma ß-
hydroxybutyrate was lowest at calving
but was not affected by treatment.
Health disorders (retained placenta,
ketosis, hypocalcemia, displaced aboma-
sum, metritis) were low across all
treatment groups. Cattle receiving either
PG or CP at calving had a significantly
lower incidence of metritis compared
with control animals (P<0.05). Aver-
aged across all trial periods, animals
receiving PG had 3.1 kg/d greater milk
production than those receiving the
control drench (P<0.05).
(Key Words: Calcium, Oral Drench-
ing, Energy, Transition, Periparturient
Problems.)
Introduction
At the onset of lactation, the dairy
cow must cope with a tremendous
increase in both calcium and energy
demand by the mammary gland.
Cows failing to meet these demands
can develop milk fever or ketosis.
Though the severe hypocalcemia of
milk fever is rather easily treated by
intravenous injection of calcium salt
solutions, cows that have recovered
from milk fever are less productive
and more susceptible to other meta-
bolic and infectious diseases (6, 7,
23). Cows that develop clinical
ketosis are also at increased risk of
developing left displaced abomasum
and retained placenta (5). Bertics et
al. (1) demonstrated that the lack of
DMI observed in most cows at
calving and the ensuing energy
deficiency were particularly detrimen-
tal to the cow in that it stimulated
lipolysis and greatly accelerated
deposition of fat in the liver on the
day of calving. Although dietary
manipulations can reduce the inci-
dence of milk fever and ketosis (2, 9,
15, 19), they are not always practical,
and their effectiveness is compro-
mised if feed intake declines.
Oral administration of large
amounts of calcium salts to force
calcium into the blood by passive
diffusion can be used to increase
blood calcium concentration during
the periparturient period. Calcium
ASE
S
TUDY
: Evaluation of Calcium
Propionate and Propylene Glycol
Administered into the Esophagus
of Dairy Cattle at Calving1
C
S. R. STOKES*,2, PAS, and J. P. GOFF†
*Department of Animal Science, Texas A&M University System, Stephenville, TX 76401 and
†USDA, Agricultural Research Service, National Animal Disease Center, Ames, IA 50010-0070
1Supported in part by a gift from Kemin In-
dustries, Inc., Des Moines, IA 50301-0070.
2To whom correspondence should be ad-
dressed: sr-stokes@tamu.edu

116
Stokes and Goff
chloride will rapidly acidify the cow’s
blood and urine; however, it also can
cause metabolic acidosis in high or
repeated doses, which limits the
amount of calcium that can be
administered. Additionally, calcium
chloride is rather irritating to the
cow’s mouth and has been implicated
as a cause of ulcers in the mouth,
esophagus, rumen, and abomasum in
some cows (26).
Several compounds, if adminis-
tered orally, can serve as glucose
precursors in ruminants. Propylene
glycol has gained commercial use
based on the concept that it has an
advantage over common dietary
glucose precursors, such as lactate
and propionate, in that it is generally
not degraded in the rumen and
passes into the blood intact (10).
However, it now appears that a
portion of the PG given to the cow is
metabolized within the rumen to
propionate (16). Grummer et al. (16)
reported increased glucose and
insulin levels, with decreased nones-
sential fatty acids (NEFA) and ß-
hydroxybutyrate, in response to PG
dosage during feed intake restriction.
Results from that study suggest that a
dose of 296 mL was almost as effec-
tive as a dose of 887 mL in reducing
lipid mobilization. However, some
authors have reported higher intakes
(>500 mL) of PG to be toxic, with
symptoms ranging from poor rumen
function to incoordination and
depression of consciousness (4, 17,
22).
Recently, CP has been incorpo-
rated into drenches because it pro-
vides gluconeogenic propionate in
addition to calcium to the cow (13).
Though its effects on blood calcium
are not as rapid as with calcium
chloride, CP may have a more sus-
tained action. Oral delivery of 50
to100 g calcium as CP will increase
plasma calcium concentrations for
several hours in dry cows, which
TABLE 1. Ingredients and composition of diets.
Cow diets Heifer diets
Close-up Fresh Lactation Close-up Fresh Lactation
Ingredients dry (1–15 DIM)a(>15 DIM) dry (1–15 DIM) (>15 DIM)
(kg fed per day, DM basis)
Corn silage 4.1 5.4 8.4 2.5 3.4 2.5
Alfalfa hay 4.9 6.2 6.7 4.5 4.0 10.7
Corn 2.0 4.5 8.1 1.8 2.7 6.9
Whole cottonseed 0.5 1.4 2.7 0.5 0.9 2.1
Cottonseed hulls 1.3 0.0 0.0 0.9 0.0 0.0
Protein + fat supplement 0.3 3.4 4.1 0.6 2.3 3.6
Close-up dry cow anionic premix 1.8 0.0 0.0 0.0 0.0 0.0
Compositionb (DM basis)
Crude protein, % 14.0 18.5 18.0 14.5 18.5 17.5
Net energy (lactation), mcal/kg 1.50 1.68 1.71 1.45 1.68 1.72
NDF, % 35 27 28 41 27 28
NFCc, % 41 41 42 32 42 42
Calcium, % 1.1 1.0 0.8 0.7 1.0 0.8
Phosphorus, % 0.35 0.35 0.42 0.31 0.57 0.43
Magnesium, % 0.36 0.28 0.26 0.30 0.28 0.27
Sulfur, % 0.44 0.24 0.20 0.23 0.21 0.20
Potassium, % 1.4 1.4 1.4 1.5 1.4 1.3
Sodiumd, % 0.19 0.21 0.18 0.15 0.21 0.18
Chlorined, % 0.80 0.26 0.25 0.18 0.25 0.24
Vitamin A, kIU supplemented/d 172 215 154 182 118 154
Vitamin D, kIU supplemented/d 43 63 53 54 40 53
Vitamin E, IU supplemented/d 1,861 742 617 3,000 467 617
DCADe, meq/100 g dietary DM –623 24262522
aDIM = days in milk.
bDiet composition calculated from actual forage chemical analyses. Concentrate and mineral values are those found in NRC tables.
cNFC = nonfiber carbohydrates.
dLactating cattle were offered additional free-choice salt.
eDietary cation-anion difference (DCAD) values were calculated with the following equation: [(% Na/0.023) + (% K/0.039)] – [(% Cl/
0.0355) + (% S/0.016)].

117
CASE STUDY: Oral Drenching with Calcium or Energy at Calving
suggests it could prove a useful aid in
amelioration of the acute hypocalce-
mia associated with the onset of
lactation in dairy cows. The objec-
tives of this study were to determine
the effects of supplying supplemental
energy (PG) or calcium plus energy
(CP) as an oral drench at calving on
blood measurements, health events,
and milk production in a commercial
dairy.
Materials and Methods
Holstein cattle were sorted by
parity (heifers = first lactation or
cows = second or greater lactation)
and assigned to treatment. Cows and
heifers were managed in similar
fashion but were housed in separate
pens from the dry period through
mid lactation. Animals were moved
from the close-up dry pen into a
maternity barn ca. 10 d prior to their
projected calving date (or by physical
signs of an early calving). Rations
were delivered as a complete total
mixed ration (Table 1). Cows were fed
a negative dietary cation-anion
difference (DCAD) diet formulated to
achieve a urine pH of 6.5. Urine was
measured weekly, and the DCAD
supplement was adjusted according
to pH. Heifers were fed a traditional
close-up ration.
Animals received the assigned
drench within 4 h of calving and
again 24 h post-calving. Treatments
were 9.5 L water (control), 9.5 L water
plus 300 mL (310 g) PG; or 9.5 L water
plus 0.68 kg CP (NutroCal®; Kemin
Industries, Inc., Des Moines, IA). All
drenches were delivered into the
esophagus via an esophageal feeder
tube connected to a bilge pump
(Springer-McGrath Esophageal Feeder
System, McCook, NE). Each PG
TABLE 2. Metabolic disorder occurrences.
Occurrence, Average DIMbOccurrence in Occurrence in
Disorder Treatmentatotal number at occurrence heifers, number cows, number
Retained placenta Control 0
PG 3 1 1 2
CP 0
Ketosis Control 1 7 0 1
PG 0
CP 2 15 1 1
Hypocalcemia Control 1 0 0 1
PG 0
CP 0
Displaced abomasum Control 1 4 0 1
PG 0
CP 3 61 1 2
Metritis Control 6 8 3 3
PG 1 8 0 1
CP 0
aCP = calcium proprionate; PG = propylene glycol.
bDIM = days in milk.
Figure 1. Effects of experimental oral drench on plasma calcium levels (mean + SE) in heifers
(H) and cows (C). Drench treatments: Control (C) = 9.5 L water; PG = 9.5 L water + 300 mL
propylene glycol; CP = 9.5 L water + 0.68 kg calcium propionate. Blood samples taken a 0
and 24 h were obtained before drenches were administered.

118
Stokes and Goff
drench delivered 4.08-mol glucose
precursor per drench (total treatment
= 8.16 mol glucose precursor). Each
CP drench delivered 146 g calcium
and 7.3 mol of glucose precursor
(total treatment = 292 g calcium and
14.6 mol glucose precursor). The
amount of CP administered was
chosen based on previous experi-
ments by Goff and Horst (13).
After calving, animals were moved
into their respective fresh pen and
observed daily for the first 15 DIM.
Cattle were monitored for visual and
behavioral signs of stress (appear-
ance, activity, etc.), and rectal tem-
peratures were recorded daily for early
identification of animals requiring
further veterinary attention and
diagnosis. Cattle were palpated
rectally, and uterine secretions were
scored for the presence of metritis
between 8 and 15 DIM. Health
events in the fresh period were
diagnosed by the herdsman or herd
veterinarian and recorded for each
animal. If cattle had good health
and normal temperatures at 15 DIM,
they were moved into the appropriate
lactation pen. Milk weights were
collected at monthly intervals.
Blood samples were collected prior
to each drench (calving and 24 h
later) and again on d 4 and 10.
Samples were collected by jugular or
coccygeal venipuncture, refrigerated
until transport back to lab (average
of 12 h; always <23 h), centrifuged.
Serum was harvested and frozen
(–20ºC) until subsequent analyses.
Serum determinations included
calcium, magnesium, glucose, and
NEFA. Serum calcium and magne-
sium concentrations were determined
by atomic absorption spectropho-
tometry (21). Serum ß-hydroxy-
butyrate (27), glucose (25), and NEFA
(18) were determined colorimetrically.
Statistics. Statistical analyses of
data (for blood and milk) were
performed by ANOVA using the GLM
procedures of SAS (24) with animals
blocked by parity (heifers = first
lactation and cows = second or
greater lactation). Experimental
model included age, drench, and age
× drench interaction. Monthly milk
weights were grouped into periods for
statistical purposes, according to
calving schedule. Period 1 included
milk weights obtained during the
first test in lactation; Period 2 in-
cluded milk weights obtained from
the second test in lactation, etc. The
model for blood analyses included
age, drench, time, and any interac-
tions. Means of independent vari-
ables found to be significant in the
TABLE 3. Plasma levels of calcium, magnesium, glucose, and nonesterified fatty acids (NEFA).
Heifers Cows DrenchaP
Item Average SEM Average SEM Control PG CP SE M Age Drench
Calcium, mg/dL 8.59 0.0775 8.38 0.0562 8.57 8.41 8.46 0.0788 0.0279 0.3698
Magnesium, mg/dL 1.96 0.0342 2.08 0.0248 2.06 2.00 2.00 0.0348 0.0001 0.0433b
Glucose, mg/dL 74.25 1.5932 70.14 1.1560 72.08 72.00 72.55 1.6206 0.0391 0.9696
NEFA, meq/L 0.5144 0.0200 0.5126 0.0144 0.5333c0.4649d0.5424e0.0202 0.9409 0.0216
b-hydroxybutyrate, mg/dL 6.04 0.2754 6.38 0.2015 6.19 5.91 6.53 0.2828 0.3176 0.3677
aDrench treatments: Control = 9.5 L water; PG = 9.5 L water + 300 mL propylene glycol; CP = 9.5 L water + 0.68 kg calcium propi-
onate. Blood samples taken at 0 and 24 h were obtained before drenches were administered; averages listed are across all samples.
bAlthough there was a statistically significant drench effect (P=0.05), the post-hoc test could not separate differences.
c,d,eDrench means within the same row with different superscripts are significantly different by respective P level listed.
Figure 2. Effects of experimental oral drench on plasma magnesium levels (mean + SE) in
heifers (H) and cows (C). Drench treatments: Control (C) = 9.5 L water; PG = 9.5 L water +
300 mL propylene glycol; CP = 9.5 L water + 0.68 kg calcium propionate. Blood samples
taken at 0 and 24 h were obtained before drenches were administered.

119
CASE STUDY: Oral Drenching with Calcium or Energy at Calving
experimental model were separated by
use of a Duncan’s post-hoc test. Chi-
square analysis was used to assess the
effect of treatment on the incidence
of retained placenta, clinical ketosis,
clinical milk fever, displaced aboma-
sum, and metritis and to determine
significance of group differences.
Results and Discussion
Animals (n = 169) utilized in this
trial were arranged in the following
groups. The control group consisted
of 22 heifers and 39 cows; the PG
treatment group consisted of 21
heifers and 37 cows; and the CP
group consisted of 16 heifers and 34
cows. All animals calved within a 53-
d window (March 13, 2000 through
May 5, 2000). Health events were
recorded at calving and continued
throughout the trial. Overall inci-
dences were 1.8% retained placentas;
1.8% ketosis, 0.6% milk fever, 2.4%
displaced abomasums, and 4.1%
metritis. Clinical milk fever devel-
oped in 1 of the 39 cows receiving the
control (water) drench; no incidences
of clinical milk fever occurred in cows
receiving either PG or CP. Treatments
had no significant effect on the
incidences of retained placenta,
ketosis, milk fever, or displaced
abomasum (Table 2); however, it
would be difficult to discern treat-
ment effects when the incidence of
these disorders were very low. One
case of ketosis was diagnosed in the
control group, and two cases were
diagnosed in the animals receiving
the CP; no animals receiving the PG
drench were diagnosed with ketosis.
The majority of metritis occurred
in the control group (6 diagnosed
cases out of 61 animals in the control
group), with one case in the PG
group, and no cases diagnosed in the
cattle receiving CP. Chi-square
analysis of these data indicated the
control group had a significantly
greater incidence (P<0.05) of metritis
than cattle receiving either the CP or
PG drench. The average DIM at
which metritis was diagnosed was d
8; thus, the addition of calcium or
energy at calving might have im-
proved smooth muscle contraction
and assisted in quicker uterine
involution.
Hypocalcemia has been suggested
as a causative factor for displacement
of the abomasum (8), and the work
of Oetzel (20) demonstrated that oral
calcium chloride treatment to reduce
hypocalcemia also reduced displace-
ment of the abomasum. A concern
with CP treatment is that the propi-
onate might actually induce displace-
ment of the abomasum. There is
TABLE 4. Milk production response to oral drenching.
Heifers Cows DrenchaP
Item Average SEM Average SEM Control PG CP SEM Age Drench
Period 1 32.3 0.9854 47.4 0.7096 38.2 41.2 40.3 0.9975 0.0001 0.1118
Period 2 34.2 0.9854 48.7 0.7153 41.1 40.7 42.6 1.0025 0.0001 0.4528
Period 3 36.0 1.0546 47.9 0.7889 40.8 43.2 41.8 1.0727 0.0001 0.3246
Period 4 36.3 0.9403 43.9 0.6518 39.9 40.8 39.6 0.9280 0.0001 0.6801
Average kg/d, all periods 35.4 0.8436 47.0 0.5754 39.7b42.8c41.1bc 0.8234 0.0001 0.0495
aDrench treatments: Control = 9.5 L water; PG = 9.5 L water + 300 mL propylene glycol; CP = 9.5 L water + 0.68 kg calcium propi-
onate.
b,cDrench means within the same row with different superscripts are significantly different by respective P level listed.
Figure 3. Effects of experimental oral drench on plasma glucose levels (mean + SE) in heifers
(H) and cows (C). Drench treatments: Control (C) = 9.5 L water; PG = 9.5 L water + 300 mL
propylene glycol; CP = 9.5 L water + 0.68 kg calcium propionate. Blood samples taken at 0
and 24 h were obtained before drenches were administered.

120
Stokes and Goff
TABLE 5. Average and range of days in milk by period for milk production.
Drencha
Heifers Cows P
Overall
Period averagebControl PG CP SEM Control PG CP SEM Age Drench
1 21.8 22.4 25.7 24.8 1.1072 19.8 21.1 20.9 0.7325 0.0039 0.2698
2 50.0 50.6 54.9 53.2 1.0689 47.9 48.7 48.9 0.7758 0.0011 0.2401
3 81.5 82.7 86.9 86.0 1.1305 78.3 80.5 80.2 0.8205 0.0001 0.1238
4 112.1 113.0 114.6 114.9 1.0198 109.8 111.8 111.8 0.7071 0.0178 0.3307
aDrench treatments: Control = 9.5 L water; PG = 9.5 L water + 300 mL propylene glycol; CP = 9.5 L water + 0.68 kg calcium propi-
onate.
bOverall average includes both cows and heifers across all treatments.
some evidence that propionate
within the abomasum inhibits
contractility of the abomasum, thus
increasing the risk of distension and
displacement (3). In this trial, the
incidence of displaced abomasum did
not increase as a result of CP treat-
ment. Perhaps any possible deleteri-
ous effects of propionate in the
abomasum were offset by the benefi-
cial effects of calcium entering the
blood to maintain abomasal motility.
Previous work reported CP, deliv-
ered as a concentrated drench, raised
blood calcium concentration for 4 to
6 h after treatment (13). We did not
observe any significant increases in
blood calcium level resulting from
treatment. Drenching animals with
either PG or CP had no significant
effect (P>0.10) on calcium or glucose
status of the animals when deter-
mined in blood samples taken more
than 24 h after treatment (Table 3).
There were expected differences in
blood constituent concentrations
between parity (cows typically have
lower blood calcium than heifers at
calving). In general, the herd had a
low incidence of metabolic disorders,
and most animals calved within
normal parameters of blood calcium,
magnesium, or glucose concentra-
tions.
The average plasma calcium
concentration increased over time,
and the increase was similar in both
control and treated animals (Figure
1). Plasma calcium concentrations at
calving (prior to treatment) were 7.6,
7.7, and 7.9 for control, PG-, and CP-
treated cows, respectively. Plasma
calcium concentrations were 8.1, 8.0,
and 8.4 mg/dL 24 h later for control,
PG-, and CP-treated cows, respec-
tively. After calving (10 d), plasma
calcium concentrations were 8.9, 9.0,
and 8.8 mg/dL in control, PG-, and
CP-treated cows, respectively. Inci-
dence of subclinical hypocalcemia,
defined as <7.5 mg/dL plasma calcium
(14, 20), averaged 39%. All plasma
calcium concentrations were higher
than those reported in previous work
(14), which may reflect the attention
given to maintaining an effective
DCAD in this herd.
Similar to calcium, plasma magne-
sium (Table 3) was affected by age
(average plasma magnesium was 1.96
and 2.08 mg/dL for cows and heifers,
respectively). There was a significant
drench effect (P=0.04); however, the
biological importance between
drench averages may be unimpor-
tant. The post-hoc test could not
separate differences. The plasma
responses in magnesium level by age
and drench over time are illustrated
Figure 4. Effects of experimental oral drench on plasma nonessential fatty acid (NEFA) levels
(mean + SE) in heifers (H) and cows (C). Drench treatments: Control (C) = 9.5 L water; PG =
9.5 L water + 300 mL propylene glycol; CP = 9.5 L water + 0.68 kg calcium propionate.
Blood samples taken at 0 and 24 h were obtained before drenches were administered.

121
CASE STUDY: Oral Drenching with Calcium or Energy at Calving
in Figure 2. Blood magnesium
concentrations were marginal (<2
mg/dL) in both cows and heifers on
d 4 and 10 post-drench, suggesting
inadequate dietary magnesium intake
in the lactating cow ration or inter-
ference with magnesium absorption
(11).
Drenching with additional energy,
as either PG or CP, had no effect on
blood glucose. As seen in other
studies, cattle calved with elevated
plasma glucose concentrations
(Figure 3; Table 3). These higher
blood glucose concentrations at
calving may be a result of the combi-
nation of glucocorticoid release at
calving and failure to secrete insulin
when blood calcium is reduced (12).
As lactation began, plasma glucose
levels declined but remained within
normal limits for plasma glucose.
Plasma NEFA responded to oral
drench (P=0.02; Figure 4; Table 3);
animals receiving PG had lower NEFA
levels than those receiving either the
control or CP treatment (0.533, 0.465,
and 0.542 meq/L for the control, PG,
and CP treatments, respectively).
Plasma ß-hydroxybutyrate was not
affected by oral drench (P>0.05;
Figure 5; Table 3); as expected, levels
were lowest at calving (averaging
4.74, 7.28, and 6.61 mg/dL for the
calving, 4-d, and 10-d bleed, respec-
tively). Incidence of subclinical
ketosis, defined as >10 mg/dL plasma
ß-hydroxybutyrate, appeared to be
higher in control cows than in cows
receiving PG or CP (15/39, 8/37, and
10/34 subclinical/total cows for
control, PG, and CP treatments,
respectively). Within these cases, the
control group had a greater incidence
(P<0.05) of repeat high plasma ß-
hydroxybutyrate levels (>10 mg/dL)
than cows receiving either the PG or
CP drench (8/15, 2/8, and 2/10
repeat/subclinical ketotic cows for
control, PG, and CP treatments,
respectively).
Milk production, averaged across
all periods, was 3.1 kg/d greater
(P=0.0495) for cattle receiving PG as
compared with those receiving the
water drench (Table 4). Although
not statistically significant, milk
production (averaged across periods)
was 1.4 kg/d greater for cattle receiv-
ing CP as compared with those
receiving the water drench. It ap-
peared that heifers received no
advantage in milk production from
additional calcium, but may have
benefited from additional energy in
the form of propylene glycol (Figure
6A). Goff et al. (14) observed no
significant increase in milk produc-
tion in a commercial Holstein herd
(multiparous cows only) receiving a
lower dose (352 g per drench) of CP
as a paste delivered at calving and
again at 24 h post-calving. In this
trial, cows receiving a larger dose of
CP (680 g per drench) averaged 1.8 kg
more milk per day than cows receiv-
ing the water control (Figure 6B).
Despite the higher dose of CP, this
difference in milk production was
not statistically different (P>0.05).
Period average DIM for both heifers
and cows is listed in Table 5. Differ-
ences in DIM between drench treat-
ments were evaluated for potential
effects on milk production. Differ-
ences were significant for age (heifers
vs cows; P<0.05), but there were no
differences (P>0.05) across treatments.
Figure 5. Effects of experimental oral drench on plasma ß-hydroxybutyrate levels (mean +
SE) in heifers (H) and cows (C). Drench treatments: Control (C) = 9.5 L water; PG = 9.5 L
water + 300 mL propylene glycol; CP = 9.5 L water + 0.68 kg calcium propionate. Blood
samples taken at 0 and 24 h were obtained before drenches were administered.
Figure 6. Top panel: Effects of experimental
oral drench on milk production (mean + SE)
in heifers. Milk production was averaged by
period (1 through 4). Period designates
monthly test weight; average days in milk
(DIM) for heifers in each period were 24, 52,
85, and 114 for Periods 1, 2, 3, and 4,
respectively. Drench treatments: Control =
9.5 L water; PG = 9.5 L water + 300 mL
propylene glycol; CP = 9.5 L water + 0.68 kg
calcium propionate. Bottom panel: Effects
of experimental oral drench on milk
production (mean + SE) in cows. Milk
production is averaged by period (1 through
4). Period designates monthly test weight;
average DIM for cows in each period were 21,
49, 80, and 111 for Periods 1, 2, 3, and 4,
respectively.

122
Stokes and Goff
Implications
Supplying both additional cal-
cium and energy during the meta-
bolic and feed intake challenge
imposed at calving may be of benefit
to the cow. Hypocalcemia results in
the loss of muscle tone in the gut,
uterus, and teat sphincter. This loss
of muscle tone, combined with the
immunosuppression of excess cortisol
at calving, predisposes these animals
to displaced abomasum, retained
placenta, uterine prolapse, and
mastitis. Additionally, the reduced
feed intake often noted with hypoc-
alcemic conditions further aggravates
the negative energy balance com-
monly observed in early lactation.
Even if clinical milk fever or ketosis is
not prevalent in the older cows, as
was the case in this herd, the cost of
the preventative oral treatment may
be justified by potentially higher milk
yields and reduced health complica-
tions.
Acknowledgments
The authors thank the M. J.
Schouten Dairy (Stephenville, TX) for
use of their cows and access to
records. Appreciation is also ex-
tended to Cindy Hauber (USDA,
Agricultural Research Service, Ames,
IA) for laboratory analyses and Joe
Pope and Curtis Brawley (Texas
Agricultural Extension Service) for
assistance with sample collection.
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