Indian J. Anim. Res., 50 (3) 2016:338-348
AGRICULTURAL RESEARCH COMMUNICATION CENTRE
Print ISSN:0367-6722 / Online ISSN:0976-0555
www.arccjournals.com/www.ijaronline.in
Relationship of blood metabolites with reproductive cyclicity in dairy cows
Muhammad Ubaidullah Qureshi 1, Muhammad Subhan Qureshi 2, Rajwali Khan* 2, Abdur Rahman 2,
Syed Muhammad Sohail2, Asim Ijaz2, Ijaz Ahmad, Shakoor Ahmad, Mohammad Shoaib and Abdul basit
Department of Livestock Management, Breeding and Genetics,
The University of Agriculture Peshawar Pakistan 25120.
Received: 24-08-2015
Accepted: 11-01-2016
DOI: 10.18805/ijar.10713
ABSTRACT
A total of 40 dairy cows in early lactation (60 to 90 days) of four different breeds were selected, comprising 10 animals
each from Holstein Friesian (HF), Jersey (J), Achai (ACH) and F1 (HF x Sahiwal). All cows were multiparous with body
weight 250-400 kg and milk production ranged from 3 to 12 kg/day. Blood samples were collected from each animal at
fortnight intervals for 90 days. In the present study, 65 % of cows reestablished estrus while 35 % cows remained anestrous,
80 % of Holsteins showed estrus followed by 70 % of Jersey and F1 cows while in Achai breed showed only 40 % and 60
% cows remained anestrous. Blood glucose and daily milk yield significantly affected post partum estrus (P<0.01) while
serum total protein and triglycerides concentration in blood did not affect post partum estrus. The serum glucose level was
lower (39.93 ± 3.14 mg/dl) two months before and showed an increasing trend (49.63 ± 2.47 mg/dl) towards commencement
of estrus as well as during estrus (48.20 ± 2.42 mg/dl) and then a declining trend was observed. Mean concentration of
serum glucose was significantly higher in Jersey (52.50 ± 2.09 mg/dl) followed by F1 (39.68 ± 1.45 mg/dl), HF (38.85 ±
1.77 mg/dl) and Achai (33.30 ± 2.17 mg/dl) respectively. Breed type significantly affected blood glucose (P < 0.05) in
jersey cows whereas both blood glucose and triglycerides were significantly affected (P < 0.001 and P < 0.05, respectively)
in F1 cows.
Key words: Blood metabolites, Glucose, Post partum estrus, Triglycerides, Total proteins.
INTRODUCTION
In dairy industry, fertility is crucial for the genetic
improvement in a herd and the replacement of culled cows.
The ever increasing demand for milk and meat has compelled
both farmers and researchers for selection of genetically
superior cows. Genetic improvement of dairy cows has
markedly increased milk yield over the last three decades
but it has been associated with decreased reproductive
efficiency (Lucy 2001). High milk yield requires high dietary
intake and altered patterns of metabolism and these outcomes
seem to be associated with sub fertility (Gutierrez et al.,
2006). The modern high-producing dairy cow partitions a
greater proportion of available nutrients towards milk
production at the expenses of body reserves and reproduction
(Collard et al., 2000). Selection for increased milk yield has
produced cows that are better able to mobilize body tissue
reserves to support milk production (Pryce et al., 2001).
Consequently, even when nutrient intake is increased to high
levels, the outcome is simply an increase in milk production
without necessarily an improvement in reproductive
performance (Horan et al., 2004). Increased genetic potential
for milk production has been associated with a decline in
fertility of lactating dairy cows.
Impaired fertility has a multifactorial background.
One of the most important factors influencing the
reproductive cyclicity of cattle is the presence of
comprehensive metabolic changes around parturition and in
early lactation. The metabolic demands of higher production
may be related to the decline in reproductive performance
of cows. During early lactation, increasing dietary intake
fails to keep pace with rising milk production. The resultant
negative energy balance (NEB) and rate of mobilization of
body reserves appear directly related to the postpartum
interval, to first ovulation and lower conception rate (Butler
et al., 1981). Negative energy balance probably acts similarly
to under-nutrition and may manifest in delayed ovarian
activity by impinging on pulsatile secretion of LH. Lower
availability of glucose and insulin may also decrease LH
pulsatility or limit ovarian responsiveness to gonadotropins.
Physiological pathways by which the hypothalamicpituitary-ovarian axis is informed about the energetic status
of the animal are very complex and involve several
metabolites and hormones. Among the metabolites which
are required for proper function of the reproductive processes
in dairy cows, glucose is the most important (Short and
Adams, 1988). Glucose acts as primary metabolic fuel for
the central nervous system and inadequate availability of
utilizable glucose reduces hypothalamic release of GnRH
(Keisler and Lucy, 1996; Wetteman et al., 2003). The
hypothalamus detects low blood glucose in a threshold-
*Corresponding author’s e-mail: rajwalikhan@aup.eud.pk. 1Department of Livestock and Dairy Development Government of Khyber Pakkhtunkhwa
Peshawar 2Department of Livestock Management, Breeding and Genetics, The University of Agriculture Peshawar Pakistan 25120.
Volume 50 Issue 3 (2016)
dependent manner in such a way that GnRH secretion will
be impaired in case of inadequate glucose availability
(Randel, 1990; Dhuyvetter and Caton, 1996). Stimulation
beyond the threshold to promote GnRH secretion is possible
by increasing gluconeogenesis via dietary manipulation
(Randel, 1990).
Although it is difficult to ascertain if specific
nutrients limit reproduction through common or discrete
mechanisms, appropriate quantities of the nutrients are
required for optimal reproduction. The lack of any proper
ration formulation practices lead to excessive or deficient
intake of some nutrients which may affect the reproductive
performance of cows. The present study is therefore designed
with the following objectives:
1. To study the reproductive cyclicity of four breeds
(Jersey, Holstein Friesian, F1 and Achai) of dairy cows.
2. To study the relationship of blood glucose, total protein
and triglycerides levels with reproductive cyclicity.
MATERIALS AND METHODS
The present study was designed to investigate the
relationship of blood metabolites with reproductive cyclicity
of various breeds of dairy cows. The study was performed
at the Government Cattle Breeding and Dairy Farm
(CB&DF) Harichand, District Charsadda.
Selection of animals : A total of 40 dairy cows in early
lactation (60 to 90 days after parturition) of four different
breeds were selected from a herd of 96 lactating cows at
CB&DF Harichand. These included 10 Holstein Friesian
(HF), 10 Jersey (J), 10 Achai (ACH) and 10 F 1 (HF x
Sahiwal) cows. Reproductive cyclicity and blood metabolites
were monitored. All cows were multiparous with body weight
250-400 kg and milk production ranged from 3 to 12 kg/
day.
All the cows were kept on the same ration during
90 days experimental period. The experimental animals were
offered green fodder (berseem, barley and oats) ad libitum
and farm mixed concentrate mixture containing 18% crude
protein and 72% TDN at a scale of 1kg per 3kg milk produced
as per prevailing practice at the farm. The concentrate
mixture consisted of wheat bran (25%), cotton seed cakes
(23%), maize gluetin (30%), rice polish (10%), molasses
(10%), DCP (1%) and sodium chloride (1%).
Blood sample collection: Blood samples from each cow of
all four breeds were collected through jugular vein puncture
at fortnight intervals to estimate blood glucose, protein
and triglycerides levels. Blood sample of about 8-10 ml was
taken into a test tube without anti-coagulant and allowed to
clot at room temperature and subsequently kept in refrigerator
at 4oC for half an hour. Serum was separated through
centrifugation at 1500 rpm for 15 minutes and was stored at 20oC until analyzed. During the experimental period, a
total of 240 serum samples were collected for analysis.
339
Serum analysis: The blood serum was analyzed for glucose,
total protein and triglycerides using commercial kits.
Manufactures instructions were followed for sample
preparation and analysis, names of manufacturer companies
and country are given under respective headings below.
Absorbance of sample was recorded through
spectophotometry and the results were interpreted using
guidelines given by the manufactures.
Determination of blood glucose : Blood glucose levels
were determined through commercial Human kit made
Centronic, Germany which works on the Enzymatic
Colorimetric principle (Trinder 1969). Glucose is determined
after enzymatic oxidation in the presence of glucose oxidase.
Hydrogen peroxide reacts under catalysis of peroxidase with
phenol and 4-amino-antipyrine to form a red violet dye
quinoneimine. The intensity of the color is proportional to
the glucose concentration in the sample.
About 10 l of serum sample or standard was
pipetted into 1000 l of working reagent (supplied with the
kit) and after mixing, incubated for 10 minutes at 37oC.
Exposure to direct sunlight was avoided. The absorbance
was read at 550 nm using spectrophotometer. The test was
performed at 25-37oC and the colour stability was upto 30
minutes. Concentration of glucose in the serum was
determined as follow:
ΔA sample
ΔA standard
× 100 = Concentration (mg/dl)
Determination of total blood protein: Serum Total proteins
were determined using commercial kit of DiaSys
international France which works on the principle of Biuret
method as described by Slater (1986). Under alkaline
conditions substances containing two or more peptide bonds
form a purple complex with copper salts in the reagent.
Serum sample or standard of 20 l was mixed with
1000 l of reagent 1 (sodium hydroxide 0.2 M and sodium
potassium tartrate) and incubated for 5 minutes at 37oC. 250
l of reagent 2 (sodium hydroxide 0.2 M, sodium potassium
tartrate, potassium iodide and copper sulfate) was added
followed by incubation for 5 minutes. The absorbance was
recorded through spectrophotometer at 540 nm. Although
the color was stable, all readings were taken within 10
minutes of sample preparation.
Determination of blood triglycerides : Serum triglycerides
were determined using commercial kits of Centronic,
Germany (Koditschek 1969).
Serum triglycerides were hydrolyzed to glycerol
and free fatty acids by lipoprotein lipase. In the presence of
Adenosine-tri-phosphate and glycerol kinase, the glycerol
was converted to glycerol-3-phosphate, which then was
oxidized by glycerol phosphate oxidase to yield hydrogen
peroxide. The oxidative condensation of ADPs (N-Ethyl-N3-sulfopropyl-3-methoxyaniline) and 4-aminophenazone in
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INDIAN JOURNAL OF ANIMAL RESEARCH
the presence of peroxidase and hydrogen peroxide produced
a rose colored dye 4-p-benzoquinone-monoimino-phenazone
(Young, 2000).
10 l serum sample was mixed with 1000 ìl of
working reagent (supplied with the kit) and was incubated
for 5 minute at 370C. The absorbance was read at 550 nm
using spectrophotometer and the results were calculated as
under.
Conc. T riglycerides (mg/dl) =
Δ A sa mp le
ΔA
X 200
C al.S TD
Clinical examination of cows: The selected cows were
examined clinically three times on different days in a week
while rectal palpation of the cows was performed when
needed. For detection of cows in estrus, three daily visual
observations for 30 minutes at 0700, 1500, and 1900 h were
made. Estrus detection was based upon observation of
“standing heat” of the cows. Estrus symptoms included
vaginal mucus, bellowing, mounting and standing to be
mounted. Estrus was also confirmed through rectal palpation
of the reproductive organs and mucus discharge on
squeezing.
RESULTS AND DISCUSSION
This research work was conducted to study the
relationship of blood metabolites with reproductive cyclicity
in dairy cows. The results are reported under various subsections dealing with effect of age and breeds, postpartum
day and relationship of occurrence of estrus with blood
metabolites levels in dairy cows.
Relationship of blood metabolites with occurrence of
estrus
Serum glucose: Blood glucose significantly affected post
partum estrus (P<0.01) as illustrated in Table 1. The serum
glucose level was lower (39.93 ± 3.14 mg/dl) two months
before and showed an increasing trend (49.63 ± 2.47 mg/dl)
towards commencement of estrus i.e. one month before
estrus. At the time of estrus serum glucose level was 48.20 ±
2.42 mg/dl. Afterwards a declining trend in the glucose level
was observed (Table 1 and figure 1). These findings clearly
indicate the significant effect of serum glucose in supporting
the occurrence of estrus. The lowest serum glucose was found
in anestrous cows 35.74 ± 1.57 mg/dl.
→ Estrus
Cows in standing estrus were inseminated
artificially. Repeat breeders after 4 inseminations were sired
naturally. The cows with the history of prolonged absence
of estrus were examined twice at 11days interval to assess
the ovarian status and those with smooth ovaries on both
examinations were confirmed as cases of anestrous.
Data analysis: The collected data were maintained in
Microsoft Excel files. Means of blood metabolites were
compared for various groups through analysis of variance
for breed and post partum estrus interval (PPEI). Computer
software SPSS-10 (1999) was used for data analysis. Means
were compared and ranked through Duncan’s multiple range
tests as dscribed by Steel and Torrie (1982).
Fig 1: Changes in serum glucose in relation to occurrence of estrus in dairy cows.
Table 1: Changes in blood metabolites levels in relation to occurrence of estrus in dairy cows (Means ± SE).
Post estrus interval
(in months)
-2
-1
1
2
3
Anestrous
Probability level
a,b,c,d
Glucose (mg/dl)
Total Protein (g/dl)
Triglycerides (mg/dl)
39.93c ± 3.14
49.63a± 2.47
48.20a ± 2.42
45.29ab ±4.10
44.06ab ± 3.95
35.74c±1.57
0.01
14.90 ± 0.69
17.34 ± 0.78
16.05 ± 0.52
15.92 ± 0.65
16.07 ± 0.87
16.14 ± 0.38
0.09
18.68 ± 1.32
18.00 ± 1.58
16.40 ± 0.85
17.43± 2.14
20.11 ± 2.17
19.17 ± 0.84
0.72
Means within the same column having different superscript are significantly different.
Daily Milk Yield (kg/day)
11.30a ± 0.60
10.52ab ± 0.80
9.91bc ± 1.04
9.00c ± 0.99
5.83d ± 1.12
6.95d ± 0.43
0.01
Volume 50 Issue 3 (2016)
Serum total protein: Non significant effect of serum total
protein on post partum estrus was observed (Table 1). The
serum total protein recorded two months before estrus was
14.91 ± 0.69 g/dl. One month before occurrence of estrus,
serum total protein increased to 17.34 ± 0.78 g/dl. After
occurrence of estrus, serum total protein decreased to 16.05
± 0.52 g/dl one month after estrus and 15.92 ± 0.65g/dl two
months after estrus. Serum total protein recorded in anestrus
cows was 16.14 ± 0.38 g/dl. Although the effect of serum
total protein on occurrence of estrus was statistically non
significant, the concentration increased to 17.34 ± 0.78 g/dl
one month before estrus and then showed a declining trend
afterwards (figure 3).
Serum triglycerides: The effect of triglycerides on post
partum estrus was found non significant. The serum
triglycerides level was higher two months before estrus
(18.68 ± 1.32 mg/dl) followed by decline near the occurrence
of estrus (18.00 ± 1.58 mg/dl) and one month after estrus
(16.40 ± 0.85 mg/dl) while further increasing trend was
observed later on (Table 1 and figure 2). Serum triglycerides
recorded in anestrous cows were 19.17 ± 0.84 mg/dl. The
overall effect of serum triglycerides on the occurrence of
estrus was non significant statistically.
daily milk yield was higher (11.30 ± 0.60 kg/day) two months
before estrus which gradually declined one month before
estrus to 10.52 ± 0.80 kg/day. This decline in daily milk
yield persisted to 9.91 ± 1.04, 9.00 ± 0.99, and 5.83 ± 1.12
kg/day one month, two months and three months after
occurrence of estrus respectively (figure 2). The average milk
yield recorded in anestrous cows was 6.95 ± 0.43.
The Breed effect: Results of blood metabolites (mean ±
SE) in various breeds of cows are given in Table 2.
On overall basis, breed type has significantly
affected the glucose concentration while protein and
triglycerides did not respond to difference in breed. Mean
concentration of serum glucose was significantly higher (P
< 0.001) in Jersey (52.50 ± 2.09 mg/dl) followed by F1, HF
and Achai (39.68 ± 1.45 mg/dl, 38.85 ± 1.77 mg/dl and 33.30
± 2.17 mg/dl respectively (figure 4).
Although the breed effect on concentration of serum
total protein was non-significant, the data trend showed
higher concentration in Jersey followed by Holstein Friesian,
Achai and F1.
The effect of breed on serum triglyceride levels was
also non significant but the data trend revealed higher level
found in Achai was 21.93 ± 1.42 mg/dl followed by HF
(18.08 ± 0.95 mg/dl), F1 (17.42 ± 0.87 mg/dl) and Jersey
(16.52 ± 0.90 mg/dl).
→
Estrus
Daily milk yield: The effect of post partum estrus on daily
milk yield was statistically significant (Table 1). Average
341
Fig 2: Changes in blood triglycerides (solid squares) concentration and milk yield (solid triangles) in relation to occurrence of estrus
in dairy cows.
Table 2: Effect of breed on blood metabolites in dairy cows (Means ± SE).
Blood metabolites
Cow Breed
Holstein Friesian
Jersey
F1 (HF x Sahiwal)
Achai
Probability level
a,b,c
Glucose (mg/dl)
b
38.85 ± 1.77
52.50a ± 2.09
39.68b ± 1.45
33.30c ± 2.17
P<0.001
Total Protein (g/dl)
Triglycerides (mg/dl)
16.25 ± 0.47
16.43 ± 0.49
15.63 ± 0.53
16.05 ± 0.45
0.44
18.08 ± 0.95
16.52 ± 0.90
17.42 ± 0.87
21.93 ± 1.42
0.64
Means within the same column having different superscript are significantly different.
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INDIAN JOURNAL OF ANIMAL RESEARCH
Metabolites effects within breed
Holstein Friesian breed: Blood metabolites had non
significant effect upon the occurrence of estrus in Holstein
Friesian cows (Table 3). The blood glucose and total protein
elevated before the occurrence of estrus while triglycerides
level showed a decline towards estrus. In anestrus cows,
higher concentration of blood triglycerides and lower blood
glucose and total protein levels were observed.
Jersey breed: Post-partum estrus was significantly affected
by blood glucose (P < 0.05) in Jersey breed while total protein
and triglycerides showed non significant effect (Table 4).
Blood glucose level remained lowest in anestrus animals
(44.16 ± 4.28 mg/dl), increased two months before estrus
up to 51.00 ± 3.30 mg/dl and increased further to 57.12 ±
5.14 mg/dl one month before the occurrence of estrus;
remaining higher later on (figure 5).
(P < 0.001 and P < 0.05, respectively) whereas total protein
had non significant effect upon the occurrence of estrus in
this breed. Blood glucose level increased form 44.74 ± 4.93
mg/dl to the higher level of 48.56 ± 3.00 mg/dl one month
before estrus occurrence (Table 5). Lowest glucose level of
33.63 ± 2.20 mg/dl were recorded in anestrus cows.
Triglyceride level showed totally opposite trend in F1 cows
as compared to other breeds studied in this experiment.
Triglyceride level two months before the occurrence of estrus
was 16.50 ± 3.68 mg/dl which elevated to 18.44 ± 3.06 mg/
dl prior to estrus commencement. Higher triglyceride level
(22.75 ± 2.73 mg/dl) was recorded two months after
occurrence of estrus and lower level (16.00 ± 0.91 mg/dl)
was observed in anestrus cows.
Achai breed: In the present study, the post partum estrus in
Achai cows was not affected by blood metabolites (Table
Crossbred cows: Occurrence of estrus in F1 cows was
significantly affected by blood glucose and triglyceride levels
Fig 3: Changes in serum glucose (solid squares) and total protein
Fig 4: Effect of breed on blood metabolites concentrations (blood
glucose, mg/dl, horizontal lines; total protein, g/dl, vertical lines;
and triglycerides mg/dl, dots) in dairy Cows: (HF= Holstien
Fresien. J= Jersey. F1=Sahiwal x HF. Ach= Achai). Concentration
of serum glucose was significantly higher in Jersey (P < 0.05).
Table 3: Changes in blood metabolites with pre and post estrus intervals in Holstein Friesian breed (Means ± SE).
Post estrus interval (in months)
-2
-1
1
2
3
Anestrous
Probability value
Glucose (mg/dl)
Total Protein (g/dl)
Triglycerides (mg/dl)
34.00 ± 2.86
44.88 ± 4.28
47.00 ± 4.93
38.00 ± 1.72
36.00 ± 5.13
37.35± 2.96
0.22
15.4 ± 0.83
19.01 ±1.36
14.87 ± 1.08
16.03 ± 1.24
15.04 ± 3.08
16.44 ± 0.83
0.19
19.69 ± 1.79
17.00 ± 3.14
15.38 ± 2.35
13.50 ± 0.64
13.33 ± 5.90
20.00 ± 1.48
0.28
Table 4: Changes in blood metabolites with pre and post estrus intervals in Jersey breed (Means ± SE).
Post estrus interval (in months)
-2
-1
1
2
3
Anestrous
Probability level
a,b
Glucose (mg/dl)
b
51 ± 3.30
57.12 ± 5.14 ab
57 ± 1.99 ab
61.5 ± 3.57 ab
71.33 ± 5.18 a
44.16 ± 4.28 b
0.03
Total Protein (g/dl)
Triglycerides (mg/dl)
15.32 ± 1.23
16.8 ± 1.12
16.87 ± 0.43
15.39 ± 1.44
15.12 ± 2.69
16.96 ± 0.66
0.77
18.86 ± 1.62
19.75 ± 2.47
15.4 ± 0.91
12.37 ± 2.88
19.33 ± 1.20
16.25 ± 1.54
0.34
Means within the same column having different superscripts are significantly different.
Volume 50 Issue 3 (2016)
343
Fig 5: Changes in blood metabolites (blood glucose, mg/dl, ; total protein, g/dl, ■; and triglycerides, mg/dl, ▲) with pre and post estrus
intervals and anoestrus (Anes) in Jersey breed. Blood glucose was significantly different (P < 0.05) during various months.
6). The blood glucose level in Achai cows showed an
increasing trend towards commencement of estrus and after
estrus occurrence, the trend became inconsistent. Total
protein remained almost persistant throughout all the pre
and post partum estrus months.
The present study was conducted to evaluate the
effect of blood metabolites (Glucose, total serum protein
and triglycerides) and their relation with reproductive
cyclicity of different breeds of cows i.e. Holstein Friesian,
Jersey, Crossbred (F1) and Achai. For this purpose a total of
240 blood samples were collected and daily milk yield of
selected cows were recorded for 90 days.
Relationship of blood metabolites with occurrence of
estrus
In the present study, 65 % of cows reestablished
estrus while 35 % cows remained anestrous during the
experimental period. 80 % of Holsteins showed estrus
followed by 70 % of Jersey and F1 cows. The reestablishment
of postpartum estrus was very low in Achai and only 40 %
of Achai cows were cyclic and 60 % remained anestrous.
The effect of blood glucose and daily milk yield on
post partum estrus was found significant. Several reports
indicated a close association between glucose availability,
serum LH, and reproductive function (McClure et al., 1978;
Table 5: Changes in blood metabolites with pre and post estrus intervals in F1 cows (Means ± SE).
Post estrus interval (in months)
-2
-1
1
2
3
Anestrous
Probability level
a,b
Glucose (mg/dl)
ab
44.74 ± 4.93
48.56 ± 3.00a
44.36 ± 2.73 ab
37.63 ± 3.44 ab
43.75 ± 5.69 ab
33.63 ± 2.20b
0.001
Total Protein (g/dl)
Triglycerides (mg/dl)
12.41 ± 0.79
14.62± 1.45
15.87 ± 0.88
16.02 ± 1.08
15.02 ± 1.60
16.04 ± 1.05
0.66
16.50±3.68 ab
18.44±3.06 ab
14.27±1.14b
22.75±2.73a
22.00±5.40a
16.00±0.91ab
0.05
Means within the same column having different superscript are significantly different.
Table 6: Changes in blood metabolites with pre and post estrus intervals in Achai cows (Means ± SE).
Post estrus interval (in months)
-2
-1
1
2
3
Anestrous
Probability level
Glucose (mg/dl)
Total Protein (g/dl)
Triglycerides (mg/dl)
39.00 ± 3.69
47.25 ± 2.46
42.17 ± 6.74
24.50 ± 1.01
40.80 ± 4.06
32.92 ± 2.70
0.16
16.63 ± 1.35
16.50 ± 0.59
16.58 ± 1.57
16.31 ± 1.45
18.47 ± 1.59
15.50 ± 0.63
0.61
12.50 ± 1.32
18.00 ± 4.60
23.33 ± 4.64
28.00 ± 5.48
19.00 ± 4.02
22.89 ± 1.86
0.37
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INDIAN JOURNAL OF ANIMAL RESEARCH
Richards et al., 1989; Funston et al., 1995). Glucose is
recognized as a major source of energy for the ovary (Rabiee
et al., 1999). This study demonstrates that with approaching
estrus, the blood glucose levels inclined to produce the
threshold for estrus.
observed in anestrous cows which is in strong agreement to
Sathish and Sharma (1991) who noticed a lower blood
glucose in non fertile animals which is an indication of
subnormal energy status of cows. 35 % animals remained
anestrous during present study.
Patil and Deshpande (1979) reported a distinct rise
in blood glucose concentration in cows during estrus due to
excitement and increased metabolic rate. Zaman et al., (1985)
observed that glucose level around estrus especially in the
fertile phase was greater in normal cycling dairy animals
than non-cycling or sub estrus cows which is in line to the
findings of the present study. The findings of the present
study is in strong agreement to Wagner and Oxenreider,
(1971); Folman et al., (1973) and Patil and Deshpande,
(1979) who reported detrimental effects of under nutrition
and low blood glucose concentrations on postpartum
cyclicity of dairy cows. Poor body condition in Achai cows
exacerbated the effects of suckling and markedly extended
the postpartum anovulatory interval partially due to the
negative influence of energy deprivation on hypothalamic
GnRH release (Rasby et al., 1992) which is in strong
agreement to Short et al., (1990); Randel, (1990) and Jolly
et al., (1995).
The present study showed that there was an increase
in serum total protein towards estrus which is in line to the
findings of Burle et al., (1995) who reported significantly
higher value of total serum protein in cyclic cows. The results
of the present study are different from the findings of Hewett
(1974) who reported that higher level of total serum protein
was associated with low fertility. However, the mechanisms
by which high level of protein adversely affect reproduction
in dairy cows is unknown (Randel, 1990). The expression
of estrus signs were more prominent in Jersey than F1 cows
which is in agreement to the findings of Beareten and
Fuquary (1992) who suggested that deficiency in protein
induced weak expression of estrum. It may be due to the
deficiency of certain amino acids required for synthesis of
gonadotropins due to low level of serum protein (Vohra et
al., 1995). The present study shows that values of
serum total protein remained steady after parturition in cows
which did not show estrus within 90 days but increased
significantly in those which did. This finding is in line with
the results of Park et al., (1980) and Thomas and Chiboka
(1984) who concluded that the composition of serum total
protein was not altered by source or amount of protein in
the ration.
When cows are weaned, even if temporarily,
glucose availability increases along with serum IGF-1 and a
return to reproductive cyclicity (Randel, 1990; Jolly et al.,
1996). Lowest serum glucose level (35.74 ± 1.57 mg/dl)
and increased triglyceride level (19.17 ± 0.84 mg/dl) were
Fig 6: Changes in blood metabolites (blood glucose mg/dl , total protein g/dl ■ and triglycerides mg/dl ▲) with pre and post estrus
intervals and anestrus (Anes) in crossbred cows. Blood glucose and triglycerides concentration were significantly different (P < 0.001
and P < 0.05, respectively) during various months.
Volume 50 Issue 3 (2016)
In the present study, the relationship of serum
triglyceride with postpartum estrus was non significant.
Triglyceride showed fluctuating trend. Firstly it showed a
decrease towards estrus and up to one month after occurrence
of estrus and then increased. Highest triglyceride level was
found three months after estrus which may be attributed to
the decrease in daily milk yield. Cow’s milk their heaviest
during the first 2 to 3 months of lactation, this heavy milking
with related increase in thyroid activity could account for
the low triglyceride during these months. During midlactation, cows are generally in a positive nutrient balance
i.e. nutrient intake exceeds nutrient outgo. As a result, losses
of body weight during heavy milking are starting to be
regained at this time. Increasing weight gain and decelerated
thyroid activity may explain the increase in triglyceride
during mid-lactation. Triglyceride decreased slightly during
later months of lactation; this decrease of triglyceride may
reflect increasing nutrient demands of the developing fetus
as well as increasing estrogen and progesterone in blood.
The result of the present study is in line to the
findings of Bronson and Manning (1991) who argued that
body fat does not have a direct causal role in regulating
ovulation. But it is clear that in situations of negative energy
balance, the quantity of fat stored in the body will influence
the composition of body tissue mobilized (Wright and Russel
1984) and the size and nature of the metabolic pool (Oldham,
1984). The mechanisms by which triglyceride may influence
the fertility of dairy cattle is unclear. Improved fertility of
cows with higher concentrations of serum triglyceride in
present study may reflect other aspects of a more positive
energy balance, rather than a causal relationship between
higher triglyceride and fertility.
The present study shows a significant relationship
between daily milk yield and occurrence of estrus (P<0.01)
which is probably due to nutrient sparing effect of decreased
milk yield chanellizing some of the metabolites towards
reproductive cyclicity. It is in line with the findings of Lucy,
(2001); Washburn et al., (2002); de Vries and Risco, (2005)
who reported that prior to the occurrence of estrus, decrease
in milk yield allowed dairy cows to partition some nutrients
towards cyclicity. They reported negative association
between fertility and milk yield. However this relationship
cannot be considered as a cause-and-effect relationship, but
rather partly explained by the antagonistic genetic correlation
between milk yield and fertility (Dematawewa and Berger,
1998 and Hansen, 2000).
This study shows that fertility and milk yield are
related inversely; that is, when milk yield increases, fertility
decreases over time. However, it does not mean that higher
producing cows within a herd, are always less fertile than
lower producing cows because high milk yield does not
always exacerbate negative energy balance (Lucy, 2001;
Tenhagen et al., 2003). These authors reported that both
345
Holstein and Jersey cows, being the highest milk producers,
have better resumption of estrus. High milk yield is not
always consistent with negative energy balance (Lucy, 2001)
and they are not at risk for infertility when compared with
low producing cows (Lucy et al., 1992).
In the present study, despite very low daily milk
yield of Achai, the reestablishment of estrus cyclicity was
also very low. Only 4 out of 10 Achai cows resumed estrus
cyclicity within the experimental period which guards the
findings of Staples et al., (1990) which states that milk
production can be a poor indicator of reproductive status of
dairy cattle.
The breed effect: In present study highly significant effect
of breed on blood glucose concentration was observed (P<
0.001) showing the highest levels in Jersey followed by
crossbred, HF and Achai. Post partum estrus was significantly
affected by blood glucose (P < 0.05) in Jersey and crossbred
cows (P < 0.001). The results of this study clearly indicate
that Jersey has the highest serum glucose and total protein
and lowest triglyceride level. Breed differences also would
reflect any differences in body size and weight for the breed.
For instance, large size does give greater consumptive
capacity and, consequently, greater milk production.
However the daily milk yield of Jersey cows was found very
low as compared to their genetic potential which may be a
potential cause of highest serum glucose level in these cows.
This discrepancy may be related to the degree of
acclimatization and/or the differences in milk production
level of the studied animals.
The high serum blood glucose observed in the highproducing cows Holstein and crossbred may be ascribed to
their increased feed intake necessary for sustained milk
production and respiratory functions. Despite of low milk
production, lowest blood glucose were recorded in Achai.
The possible reason for this may be the slow increase in dry
matter intake postpartum which resulted in poor milk
production and reproduction. Contrary to Coppock et al.,
(1974) who reported that dry matter intake progressively
increased for the first 16 wk of lactation before starting to
decline, Achai cows took a long time to reach peak feed
intakes. Reid et al., (1966) concluded that appetite was the
greatest limitation to large milk yields.
The lowest concentration of serum glucose in Achai
may also be attributed to suckling of their calves which is in
a strong agreement to the study made by Marongiu et al.,
(2002) in which glucose concentrations was affected by the
suckling treatment (P<0.01) and increased (62 vs. 67 mg/
dl) by suckling restriction. Negative energy balance during
early lactation may be a contributory factor to lowest serum
glucose level in achai. Highly significant effect of breed on
blood glucose in this study contradict the findings of Shaffer
et al., (1981) who reported non significant effect of breed
on blood glucose.
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INDIAN JOURNAL OF ANIMAL RESEARCH
Occurrence of estrus in F1 cows was significantly
affected by blood triglycerides level (P < 0.05). However in
other breeds, non significant effect of breed on serum total
protein and triglyceride was noticed. Highest total protein
was found in Jersey cows followed by Holsteins and Achai
while crossbreds showed lowest level of total protein. The
breed differences for total protein were small and non
significant which is in agreement to Kirk and Davis (1970).
Jersey cows are generally believed to calve in low body
condition, lose less body weight during early lactation (Abe
et al., 1994; Mackle et al., 1996). These observations suggest
that the depth and duration of nutrient deficit is less severe
in Jersey. Blood concentrations of non estrified fatty acids
and 3-OH are lower and appetite is less depressed during
early lactation than in cows and thus less body tissues are
mobilized.
The findings of present study are in disagreement
to Shaffer et al., (1981) who showed significant effect of
breed on total protein and triglyceride. Highest triglyceride
level was found in Achai while lowest was recorded in Jersey
cows. The possible justification for increased level of
triglyceride may be the inhibition of fat mobilization from
the adipose tissue, resulting in a sudden flux in the turnover
rate of fatty acids and leading to a higher synthesis and release
of triglycerides from the liver. It is hard to explain how such
a large amount of triglycerides may be utilized by the
mammary gland. The possibility that a fairly large portion
of these triglycerides may leave the gland via the lymphatic
system or be deposited in the glandular tissues cannot be
ruled out. It has been shown that blood fi-lipoprotein
triglycerides are more acceptable to the udder than the alipoprotein triglycerides (Welch et al., 1963). In Jersey cows,
enhanced mobilization of body reserves and partitioning of
nutrients toward milk production may be the possible reason
for low level of triglyceride. Within breed differences for
triglyceride level were also evidenced.
CONCLUSIONS
(a) Based upon this study, we suggest that the rising levels
of blood glucose one month prior to occurrence of estrus
indicated the role of this metabolite in supporting fertility
in dairy cows. Cows failing in exhibiting estrus were also
deficient in blood glucose concentrations.
(b) Higher blood glucose and total protein concentration
supported higher reproductive cyclicity in Jersey while
higher triglycerides in Achai cows were associated with
lower fertility.
(c) In crossbred cows, significant variations were observed
in blood glucose and triglycerides level showing rising
levels during pre estrus period indicating greater
adaptability to the local environment.
Recommendations
(a) The feeding management should ensure sparing of
glucose availability to support fertility in dairy cows after
meeting other requirements of the animal.
(b) Further studies are recommended to document blood
metabolic profiles of local breeds and their association
with fertility.
(c) Crossbred cows need appropriate feeding strategies for
expressing their fertility and lactation potentials.
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