Dairy cow monitoring in relation to fertility performance
D. Zaaijer1, J.P.T.M. Noordhuizen2
1 Future Fertility Systems, Torendijk 22, 7491 EV Delden
,The Netherlands
2 Dept. of Ruminant Health, Faculty of Veterinary Medicine, Utrecht University,
POBox 80151, 3508 TD Utrecht, The Netherlands
Summary
Nutrition plays a key role in the regulation of reproductive processes.
The effects of nutrition are measurable through cow characteristics like
body condition score (BCS). A decline in BCS of more than 0.5 points is
known to have negative effects on fertility. Therefore it is used as a
tool for decision-making in feeding management. However, changes in BCS
take weeks or months, which is too long for accurate and timely adjustments
in feeding management.
A scoring system which yields information about nutritional efficiency
faster and which facilitates adjustment is presented. Criteria for monitoring
rumen fill, faeces consistency, undigested faecal particles and rectal
examination are given. The data obtained through the monitoring and processing
of both the scoring items and the findings of rectal examination of ovaries
were further processed into odds ratios in order to provide the farmer
with a risk indication about his actual feeding management. It is concluded
that this scoring system is useful to attract in an early stage the farmer’s
attention to feeding inadequacies and after discussion between farmer,
veterinarian and nutritionist to make adjustments in the ration for improving
fertility performance.
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Introduction
Dairy herd fertility schemes have been operational for decades. The last
years, they form part of overall Herd Health and Production Management
programmes with an emphasis on routine monitoring of cow features (e.g.
fertility, teat end callosity assessment; body condition scoring), of
farm/management aspects (milking technique; feeding management; ration
composition) and of available data (Brand, Noordhuizen and Schukken, 1996).
Within this framework there is a need for tools which can help detect
impending problems and, hence, support the farmer in his day to day decision
making. Despite the use of these herd health programmes, recent studies
indicate a serious trend of reduced reproductive performance in dairy
herds in the UK (Esslemont, 1992; Esslemont and Kossaibati, 2000). Using
hormones for improving reproductive performance is not a solution, it
is not animal friendly and is in conflict with current consumer demand.
Moreover, at present some farmers and veterinary surgeons are disappointed
about the results of these hormonal treatments.
A different approach for improving reproductive performance is to address
the problem through the area of nutrition. Nutrition plays a key role
in the regulation of reproductive processes in the dairy cow, specifically
during the early postpartum period (Butler, Everett and Coppock, 1981;
Harrison, Ford, Young, Conley and Freeman, 1990; Roche, Mackey and Diskin,
2000). In this period, a more or less severe negative energy balance (NEB)
may occur due to the fact that there is a gap between energy intake level
and energy demand. The latter is strongly increased when the high milk
yield levels start in the first weeks postpartum. In the situation that
over-condition in the dry period occurred and feed intake was already
depressed before parturition, this negative energy balance becomes even
more expressed (Heuer, 2000). In short, lipolysis occurs, the non-esterified
fatty acid (NEFA) concentration increases and will partially be transformed
to triacylglycerides (TAGs) which are stored in the liver and hence influence
liver metabolism of providing glucose. As a consequence, there is an endocrine
unbalance affecting, among others, pulsatile luteinizing hormone (LH)
secretion and follicular development negatively (Butler and Smith, 1989;
Canfield and Butler, 1990). Cows in a negative energy balance are reported
to have low oestrogen and low progesterone secretion and a larger number
of abnormal cycles compared to traditional Friesian cows (Butler, 1999;
Lucy and Crooker, 1999; Fagan and Roche, 1986; Opsomer, 1999). Oestrus
behaviour and NEB both have a high correlation with respectively oestradiol
concentrations and dry matter intake (DMI) of 0.7 , which suggests the
importance of feeding management on potential oestrus expression (Lyimo,
Nielen, Ouweltjes, Kruip and van Eerdenburg, 2000; Villa-Godoy, Hughes,
Emery, Chapin and Fogwell, 1988).
“Not seen in heat” is one of the biggest frustrations of the
dairy farmer and is an indication that cows are not healthy. A low oestrus
intensity is reported for high yielding Holstein Friesian cows (Van Vliet
and van Eerdenburg, 1996), however nutrition was not mentioned in this
report. The effects of nutrition are reflected by a cow characteristic
like body condition score, BCS (SAC, 1976; Mulvany, 1977). The BCS is
an indicator of energy utilization for body maintenance, repletion and
productivity. It is a subjective and qualitative method to grade the extent
of subcutaneous fat over the loin, the pelvis and the tailhead cavity
of cows on a scale of 1 ( very thin ) to 5 ( over conditioned). BCS is
generally accepted as a management tool to support decision making with
respect to ration composition and feeding management (Crooker, 1997; Roche,
Mackey and Diskin, 2000; Van Saun and Wustenberg, 1997). Changes of BCS
take place over a period of weeks or months, which limits the ability
to respond with feeding management adjustments until sufficient time has
passed to detect a difference in BCS. A decline of more than half a point
of BCS has negative consequences for fertility performance (Britt, 1993;
Butler and Beam, 1993; Butler and Smith, 1989).
In certain farm situations where reproductive or production problems occur
it would be most welcome to have faster information available about the
nutritional efficiency in order to facilitate adjustment at an early stage.
Cow characteristics which can be expected to give that information faster
than BCS are: rumen fill ( RF ), faeces consistency (FC) and faecal undigested
fraction (UF) as the passage rate of ingesta through the digestive tract
takes about 1.5 to 4 days (Guard and Brand, 1996; Skidmore, Brand and
Sniffen, 1996). The amount , type and size within the undigested fraction
can be differentiated by observation. For RF, FC and UF a scoring system
has been developed.
In addition to the cow characteristics named above, rectal palpation of
cows in the postpartum period can give information about follicular size,
the size and consistency of a corpus luteum (CL) and the uterine tone
which can be used as an indicator of normal or abnormal cyclicity
The objective of this paper is to describe the scoring system for BCS,
RF, FC , UF, the rectal palpation and the relationship of scoring and
palpation results with fertility . Ultimately, the farmer should receive
nutritional advice.
Materials and methods
All cows should be observed by a team consisting of farmer or farm manager
together with the veterinary surgeon and the nutritionist during the farm
inspection. During the farm inspection, BCS, RF, FC and UF are scored
and rectal palpation by the veterinary surgeon is executed.
Rumen fill is the result of dry matter intake, ration composition, digestion
and passage rate of ingested feed. Digestibility is the result of feed
retention time in the rumen and the degradation characteristics of ingested
nutrients (Forbes, 1995). Faeces can provide valuable information about
nutritional management and digestion in the cow (Ireland-Perry and Stallings,
1993). Faeces consistency is influenced by the ratio water to dry matter,
with the undigested feedstuff in particular making up for the dry matter
portion. Additionally, fertility parameters for normal cyclicity and uterine
involution are assessed by rectal palpation. The cows more than 21 days
post partum, cows not yet served and cows with more than 3 inseminations
and not yet in calf are to be examined.
BCS
Body condition scoring is executed according to the methodology developed
by SAC(1976) and subsequently described by Mulvany (1977). The scale is
between 1 (poor; thin) and 5 (over-conditioned; fat).
Rumen fill (RF)
Standing at the left hind side of the cow the para lumbar fossa between
the last rib, the transversal processes and the hipbone is observed. The
following scores are distinguished (see Fig. 1 a to e).
Score 1: the para lumbar fossa looks very empty; the para lumbar fossa cavitates
more than a hand’s width behind the last rib and also a hand’s
width inside under the transversal processes. The fossa looks like a rectangle
when observed from the left side of the cow. Such cows typically will have
eaten little or none at all because of illness.
Score 2: the para lumbar fossa cavitates a hand’s width behind the
last rib and to a lesser extent inside under the transversal processes.
Standing at the left side of the cow, this area looks like a triangle. This
condition is often observed in normal cows in the first week postpartum.
When the RF-score does not increase after this period, this is an indication
of poor feed intake.
Score 3: the para lumbar fossa cavitates less than a hand’s width
behind the last rib and falls about a hand’s width vertically downwards
from the transversal processes and then bulges out. This is the desired
RF-score for lactating cows with adequate dry matter intake.
Score 4: the para lumbar fossa skin is covering the area behind the last
rib and arches immediately outside below the transversal processes due to
a extended rumen. Dry cows and cows in late lactation should show this score.
Score 5: the rumen is quite distended and nearly obliterates the fossa ;
the last rib and the transversal processes are not visible. This is the
score for dry cows.
Faecal consistency (FC)
Only the freshly dropped faeces should be observed. The assessment is done
visually and by applying the “boot test”. The latter means stepping
in the faecal pad and assessing the extent to which it sucks during boot
withdrawal. After complete withdrawal, watch for undigested particles standing
up and for marks of the boot sole profile in the faeces pad (see Fig. 2
a to e).
Score 1: the faeces is watery thin and not truly recognisable as faeces.
Cows with acute infectious disease (e.g. with fever or toxaemia ) may show
this score.
Score 2: faeces is thin custard-like; faeces structure can be recognised.
At dropping it splashes wide out on the floor. This condition may be noticed
from either lush spring pasture or ration imbalance.
Score 3: faeces is more thick, custard like. It makes a light plopping sound
when being dropped on the floor. It makes a well circumscribed pad which
spreads and has the thickness of about 2 cm . No sucking is felt when the
boot is retracted from the pad and a boot sole profile not visible. This
is the ideal condition and is a reflection of a well digested ration.
Score 4: stiff faeces can be observed. It makes a heavy plopping sound when
being dropped. It makes a well circumscribed pad which piles in rings and
spreads out very little. Sucking is felt after withdrawal of the boot; a
boot sole profile is left on the pad. This condition reflects an imbalance
of the ration for lactating cows and should provoke a revision of that ration.
For dry cows and heifers this score is acceptable.
Score 5: stiff faeces in balls, looking like horse faeces. A boot sole profile
is left. This condition is often observed in dry cows and heifers. It points
to a ration imbalance which needs to be corrected.
Undigested fraction (UF)
The scoring of this condition is done after the preceding one. The pad is
being assessed more closely. The surface of the pad could be shiny or dull
and one looks for undigested particles of the ration. A (gloved) handfull
of faeces is then taken and squeezed slowly. During this squeezing it is
felt whether the faeces feels rough or creamy, as homogenous or with a solid
fraction, with water pressed between the fingers, presence of undigested
particles, their type, origin and size (see Fig.3 a to e).
Score 1: the faeces has a shiny aspect and no particles are visible in the
pad. It feels like a creamy emulsion, homogenous and without feeling particles.
This is the ideal score for lactating and dry cows.
Score 2: the faeces shows a shiny aspect, a few particles are visible in
the pad. It feels like a creamy emulsion, homogenous and some particles
can be felt. Particles are small sized, partially undigested and originate
from roughage. This condition is acceptable for lactating and dry cows.
Score 3: faeces shows a dull to shiny aspect; there are particles in the
pad. It feels like rough material, not creamy, not homogenous. Some water
can be pressed between the fingers, while particles are clearly felt. When
the fist is opened, roughage and concentrate particles of varying sizes
stick to finger tips. This condition is acceptable for dry cows and heifers
but not for lactating cows.
Score 4: faeces shows a dull aspect. Fibre and other particles are visible
in the pad. It feels rough, water can be pressed between the fingers, while
particles feel prominently present. After opening the fist a compressed
ball of undigested, large sized particles (> 2 cm) mainly of a roughage
origin remains in the palm of the hand. The ration needs revision at this
condition.
Score 5: faeces shows a very dull aspect. Undigested whole particles are
clearly visible in the pad. It feels very rough, not homogenous at all.
After opening the fist a ball of whole undigested particles of all sizes
is visible in the palm of the hand. The ration needs to be revised.
Fertility parameters
Rectal palpation for ovarial structures and uterine conditions are followed
as described by Settergren (1980). The consistency for the normal CL structure
is more differentiated as: liver consistency until around D 7 to 9 of the
cycle, tight consistency until D 14 and thereafter hard. Uterine tone is
subdivided in score 1 to 5 . Score 1: sloppy , score 2 : decreased contractility,
score 3: normal contractility, score 4 : increased contractility after touching,
score 5: very contractile as it should be during oestrus.
The results of the observations are recorded on a form and a final judgement
about normal or abnormal cyclicity is made. Abnormal conditions are (1)
inactive ,with normal sized follicle of about 25 mm or less with a flaccid
uterus score 1 or 2 , (2) cystic , with too large follicle of more than
25 mm and a flaccid uterus and (3) " spongy " corpus luteum, which
is an abnormal CL with a more voluminous circumference at palpating than
a normal CL and consists of cavernous tissue at pressing, the uterine score
with this condition being 1 or 2
Of the investigated group 80 % is expected to be classified as “normal”
as a reference value.
Analysis
The scoring data and the findings from rectal palpation of the ovaries
are processed to present odds ratios (Thrusfield, 1995). In the first
step, the scoring results of RF, UF and FC per cow are compared with their
respective standard value and classified as “+” or “-“.
For example, the standard score value for RF is a score of 3 or 4; a cow
with that standard score will get a “+” mark. For FC, the
standard score value is 2 or 3, while for UF the standard score value
is 1 or 2.
In the next step of processing, the results of the “+” and
“-“ marking per cow are combined into resultant scores and
classified as either “non-deviant” or “deviant”.
For non-deviant at least two out of the three scores should mark “+”,
while for deviant at least two out of three scores should mark “-“.
Odds ratios, OR, can be calculated for cross-sectional studies like scoring
during a farm visit presented here. The OR elaborates the association
between exposure to a putative risk factor and a given outcome parameter.
An OR of >1 means there is an increased risk, an OR <1 means a decreased
risk, while at an OR of 1 there is no association between putative factor
(e.g. deviance) and the outcome of interest (e.g. finding of an ovarian
abnormality). The data are entered into a 2x2 Table for univariate analysis
and presentation of crude odds ratios.
Results
The scoring system for RF, FC and UF appeared to function well in the
field. The overall qualification of e.g. ovarian abnormality, either inactive,
cystic ovarian disease or spongy corpus luteum, was based on the outcome
of rectal palpation by the veterinary surgeon.
The data obtained through the monitoring and processing of both the three
scoring topics and the findings of rectal palpation of the ovaries were
further processed into odds ratios in order to provide the farmer with
a risk indication.
The following two 2x2 Tables are derived from two herds: one of 1200 cow
head ( of which 1127 lactating) and one of 150 cow head (of which 124
lactating).
| Ovarian abnormality found? |
| |
Yes |
No |
Deviant
resultant score |
367 |
258 |
Non-deviant
resultant score |
121 |
381 |
N= 1127 lactating cows |
The odds ratio for cows with a deviant score occurring the risk to have
concurrent ovarian abnormalities is calculated as
(367 x 381) divided by (121 x 258) which is about 4.
In this herd the cows with deviant resultant scores have a 4 times greater
risk of being assigned to the ovarian abnormalities category than cows
with non-deviant resultant scores.
| Ovarian abnormality found? |
| |
Yes |
No |
Deviant
resultant score |
59 |
11 |
Non-deviant
resultant score |
23 |
31 |
N= 124 lactating cows |
The odds ratio in this case is calculated as
(59 x 31) divided by (23 x 11) which is about 7. This means that in this
herd the cows with deviant resultant scores have a 7 times greater risk
of being assigned to the ovarian abnormality group than cows with non-deviant
resultant scores.
Discussion
The odds ratios have been calculated in a univariate way. In other words,
there has not been conducted a multivariate analysis with corrections
for confounding and interaction between factors (Thrusfield,1995). Yet,
it is possible to have a probability indicator for herd fertility problems
as related to scoring results. It is obvious that the causal relationship
between scoring results and ovarian abnormality, as defined earlier, is
in nutriton and negative energy balance (NEB); the latter specifically
for early lactation cows. The scoring methods should therefore be regarded
as proxi’s. It would also be attractive to validate the risk indications
for health disorders (e.g. ketosis, milk fever); preferably at a large
scale.
When reproductive performance of dairy cows is not as optimal as desired,
in some situations even strongly decreased, not seen in heat is a major
complaint on a dairy farm. For a low oestrus detection rate usually the
farmer or farm staff is blamed for not being observant enough. However,
on many farms with herd fertility problems most of the time abnormal values
could be recorded for both the described scoring method regarding RF,
FC, UF and rectal palpation. The deviant resultant score values can be
related to nutritional aspects like DMI, digestion and feed passage rate.
This scoring method therefore suggests that absence of oestrus expression
by the cow herself is the major problem which is predominantly caused
by nutritional imbalances.
Maximal DMI is essential to minimize the extent and duration of the NEB
(Butler and Beam, 1993; Butler, Everett and Coppock, 1981; Butler and
Smith, 1989, Roche, Mackey and Diskin, 2000). The degree of NEB in the
early postpartum period is related to the potential of a follicle to become
dominant and the ability of the follicle to produce elevated concentrations
of oestradiol (Roche, Mackey and Diskin, 2000). Moreover, it is being
reported that high concentrations of circulating NEFA’s are toxic
for follicles and apoptosis occurs in the inner cell mass (Jorritsma,
unpublished data). Energy supplementation can affect follicle growth within
7 days and is related to increased follicle size (Khireddine, 1998). These
follicles tend to have higher oestradiol secretions. With the increase
of oestradiol concentrations more intensive oestrus behaviour can be expected
(Lyimo, Nielen, Ouweltjes, Kruip and van Eerdenburg, 2000). The development
of a normal corpus luteum depends on the endocrine changes which take
place within the dominant follicle prior to ovulation and of the DMI for
normal size and progesterone production (Badinga, Thatcher, Wilcox, Morris,
Entwistle and Wolfenson, 1994; Van dehaar, Sharma and Fogwell, 1995).
As energy level affects the follicle growth in 7 days, a similar fast
effect of nutrition on corpus luteum development can be expected.
Rectal examination can give information about normal and abnormal cyclicity
by the presence and size of follicles and CL, by the consistency of CL
tissue and the uterine tone. These results in combination with RF, FC
and UF can be related to the level of energy density, energy sources and
the balance of other ration components. Abnormal conditions like cystic
ovarian follicles and inactive ovaries together with insufficient uterine
tone can be related to energy deficiency. " Spongy " corpora
lutea are an indication of an imbalance in the energy- protein ratio.
It appeared that the scoring method was useful in practice for indicating
the risk in a herd for fertility problems as related to nutritional inefficiencies.
It can also be used as a follow-up tool to see whether advised changes
in ration composition and or feeding management are reflected in the scoring
results.
Conclusion
Correction of nutrition by stimulating DMI with sufficient energy density
and the right energy sources with balanced levels for protein, mineral,
trace elements and vitamins should result in scoring values for RF, FC,
UF and cycling cows of which 80 % is within the normal ranges. The scoring
system presented here is useful to draw the farmer’s attention to
those cows that need support and to detect impending deviations in both
nutritional performance and fertility results at an early stage. It can
also be used for follow-up screening of results of nutritional advice
given earlier.
Additionally, the communication between farmer, veterinary surgeon and
nutritionist can be improved by observing (scoring) the cows together;
it creates awareness. This team approach is desired to achieve optimal
dairy herd fertility results.
Personal experience from the last years’ visits on farms with fertility
problems has shown that nutritional inadequacies are the most important
factors which cause reproductive imbalances in the high yielding dairy
cow. The solution to correct these imbalances is to adjust the feeding
management and or ration composition by team approach and, hence, improve
the herd fertility status on a dairy farm.
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