LITHUANIAN UNIVERSITY OF HEALTH SCIENCES VETERINARY ACADEMY
Faculty of Veterinary Medicine
Lina M. E. Lundholm
DIGITAL DERMATITIS IN DAIRY COWS AND ITS INFLUENCE
ON PRODUCTION AND REPRODUCTION
KARVIŲ NAGŲ DIGITALINIO DERMATITO ĮTAKA PIENINIŲ
GALVIJŲ PRODUKCIJAI IR REPRODUKCIJAI
MASTER THESIS
of Integrated Studies of Veterinary Medicine
Supervisor: Kristina de Witte
2 THE WORK WAS DONE IN THE DEPARTMENT OF ANIMAL NUTRITION
CONFIRMATION OF THE INDEPENDENCE OF DONE WORK
I confirm that the presented Master Theses “Digital dermatitis in dairy cows and its influence on production and reproduction”
1. Has been done by me.
2. Has not been used in any other Lithuanian or foreign university.
3. I have not used any other sources not indicated in the work and I present the complete list of the used literature.
Lina M. E. Lundholm
(date) (author’s name, surname) (signature)
CONFIRMATION ABOUT RESPONSIBILITY FOR CORRECTNESS OF THE ENGLISH LANGUAGE IN THE DONE WORK
I confirm the correctness of the English language in the done work. Malin Sköld
(date) (name, surname) (signature)
CONCLUSION OF THE SUPERVISOR REGARDING DEFENCE OF THE MASTER THESES
Kristina de Witte
(date) (supervisor’s name, surname) (signature)
THE MASTER THESES HAVE BEEN APPROVED IN THE DEPARTMENT/CLINIC
Department of animal nutrition
(date of approbation) (name, surname of the manager of department/clinic) (signature) Reviewer of the Master Thesis
1) ________________Prof. dr. Ramunas Antanaitis_________________________________ (name, surname) (signatures)
Evaluation of defence commission of the Master Thesis:
3
TABLE OF CONTENT
SUMMARY ... 5 SANTRAUKA ... 6 ABBREVIATIONS ... 7 INTRODUCTION ... 8 1. LITERATURE REVIEW ... 9 1.1 Digital dermatitis ... 91.1.1 Anatomy and pathogenesis ... 9
1.1.2 Etiology ... 9
1.1.3 Prevalence ... 10
1.1.4 Diagnosis ... 10
1.1.5 Treatment ... 11
1.1.6 Impact ... 12
1.2 Nutrition and milk content ... 12
1.2.1 Fat ... 12
1.2.2 Protein ... 13
1.2.3 Lactose ... 13
1.2.4 Urea ... 14
1.2.5 Somatic Cell Count (SCC) ... 14
1.3 Reproduction ... 14
1.3.1 Reproduction and DD ... 14
1.3.2 Reproduction and production ... 15
1.4 Welfare ... 15
2. METHODOLOGY ... 17
2.1 Study design ... 17
2.2 Laboratory used for analysis of milk samples ... 18
2.3 Requirement to qualify for the study ... 18
3. RESEARCH RESULTS ... 19
3.1 DD effects on milk production ... 19
3.2 Digital dermatitis effects on milk fat ... 20
3.3 Digital dermatitis effects on milk protein ... 21
3.4 Digital dermatitis effects milk lactose ... 22
3.5 Digital dermatitis effects on milk urea... 23
3.6 Digital dermatitis effects on milk SCC ... 24
4 4. DISCUSSION OF RESULTS ... 26 4.1.1 Milk yield ... 26 4.1.2 Fat ... 26 4.1.3 Protein ... 26 4.1.4 Lactose ... 27 4.1.5 Urea ... 27
4.1.6 Somatic Cell count ... 27
4.1.7 Reproduction ... 27
CONCLUSION ... 28
SUGGESTIONS/RECOMMENDATIONS ... 29
ACKNOWLEDGEMENT ... 30
5 Digital dermatitis in dairy cows and its influence on milk yield and reproduction
Lina M. E. Lundholm
Master’s thesis
SUMMARY
It is important to maintain a good welfare for highly producing dairy cows.
Failure to provide good living conditions, suitable nutrition, preventive measures of disease or adequate care once the animal turns ill will lead not only to unnecessary suffering for the animal but also a loss in production and reduced reproduction rates which in turn will cause economical loss for the farmer.
The aim of this study was to analyse milk yield, the milk parameters of fat, protein, lactose, somatic cell count and urea and the reproduction rates in a Lithuanian dairy herd that struggle with digital dermatitis.
The study comprised of 20 dairy cows of Simmental/Holstein type, out of which 10 was diagnosed with digital dermatitis and the remaining 10 was healthy cows used as a control group.
In conclusion, none of my data on milk yield or milk parameters had any statistical
significance at the rate of 5%. The detection of heat, number of inseminations done, and the number of born calves did not show anything extraordinary.
Key words: digital dermatitis, dairy cows, milk yield, reproduction, fat, protein, lactose, somatic cell count.
6 Karvių nagų Digitalinio dermatito įtaka pieninių galvijų produkcijai ir reprodukcijai
Lina M. E. Lundholm Magistrinis Darbas
SANTRAUKA
Svarbu išlaikyti gerą pieninių karvių gerovę.
Nesugebėjimas užtikrinti gerų gyvenimo sąlygų, tinkamos mitybos, prevencinių ligų priemonių ar tinkamos priežiūros gyvūnui susirgus, sukels ne tik nereikalingas gyvūno kančias, bet ir gali pabloginti guvulio produkcijos reprodukcijos rodiklius, kurie savo ruožtu sukels ekonominių nuostolių ūkiui.
Šio tyrimo tikslas buvo išanalizuoti pieno primilžį, pieno, riebalų, baltymų, laktozės, somatinių ląstelių skaičiaus bei reprodukcijos rodiklius Lietuvos pieno bandoje, kovojančioje su Digitaliniu dermatitu.
Tyrimą sudarė 20 Pieninių Simentalių / Holštenų mišrūnių karvių, iš kurių 10 diagnozuotas Digitalinis dermatitas, o likusios 10 – buvo sveikos, naudojamos kaip kontrolinė grupė.
Apibendrinant galima teigti, kad jokie pieno parametrų rodikliai neturėjo statistinio reikšmingumo.
Reikšminiai žodžiai: skaitmeninis dermatitas, melžiamos karvės, primilžis, reprodukcija, riebalai, baltymai, laktozė, somatinių ląstelių skaičius.
7
ABBREVIATIONS
DD -Digital Dermatitis
BDD -Bovine Digital Dermatitis
CT -Collective Treatments
NEBAL -Negative Energy Balance
NEFA -Non-Esterified Fatty Acids
BCS -Body Condition Score
AI -Artificial Insemination
DM -Dry Matter
DMI -Dry Matter Intake
CP -Crude Protein
MP -Metabolizable Protein
FA -Fatty Acids
LP -Lactose Percentage
MUN -Milk Urea Nitrogen
UN -Urine Nitrogen
SCC -Somatic Cell Count
8
INTRODUCTION
Animal welfare is negatively affected by pain and lameness which are common symptoms of digital dermatitis (DD) in infected cows (1,2,3).
In many countries DD is a serious problem for dairy producers. The disease has been reported worldwide since it was first described in 1974 (4).
Digital dermatitis affects up to 92% of herds in Europe, and herd prevalence ranges from 0 to 74% (5). Dairy cows not born on the specific farm are associated with economic and epidemiological consequences for the spread of DD (6).
Although disease prevention measures exist, like the use of disinfectants through foot baths, they are rarely or irregularly applied in dairy farms (7). Farmers are aware of the fact that pain is associated with limping (8), but prevention program measures are only implemented if they are aligned with their daily work schedule as well as provide certain economic benefits (9). The latter depends on the balance between the costs of losses, the cost of preventive measures, and ultimately the expected gains (10).
Reproductive performance often decrease in animals infected by DD, causing tremendous economic losses (11).
Poor reproductive efficiency in commercial dairy herds, is also associated with the physiological changes that come with high milk production (12).
An animal that is "healthy, comfortable, well-nourished, safe, can express innate behaviour and does not suffer from unpleasant conditions such as pain, fear and distress" is classified by the World Organization for Animal Health as an animal in good animal welfare (13). Cows suffering from digital dermatitis don’t belong in this classification.
The objective of this study is to evaluate the general health, production parameters and reproduction, in a dairy herd with a digital dermatitis problem.
The tasks of the work:
1. Analyse milk quantity parameters of cows diagnosed with DD and healthy cows. 2. Analyse milk quality parameters of cows diagnosed with DD and healthy cows.
3. Briefly look at reproduction data and compare cows with digital dermatitis, with healthy cows.
9
1. LITERATURE REVIEW
1.1 Digital dermatitis
1.1.1 Anatomy and pathogenesis
DD is seen in the bulbs of the heel or interdigital cleft and is an acute or chronic ulcerative lesion of the skin. Disease states are characterized by, among other things, pain and mild swelling. Usually, the lesions on the hind legs appear characteristically on the plantar aspect of the hind foot, near the interdigital space or the heels, but can also invade the horny structure of the claw and are prone to bleeding. Varying degree of spread of filiform papillae limited by a red, granular (strawberry-like) appearance, are signs of early damage (14).
Loss of superficial keratin, with a simultaneous thickening of the epithelium due to both hyperplasia and hypertrophy of epithelial cells, is seen in the early stages of the lesion. Proliferation and hyperplasia are stimulated by loss of the superficial keratin layers. One can see a necrotic change with the appearance of small holes surrounded by a large number of spirochetes in the eosinophilic superficial layers. In advanced cases, the eroded dermis is infiltrated by said spirochete, which can destroy the epidermis. The term "hairy wart disease", comes from the fact that mature lesions are more proliferative and can have long wart-like protrusions (15).
In order to recognize, treat and prevent common and unusual diseases, it is important to understand the normal anatomy of the hoof. To minimize weight-bearing stress and protect it from damage and pathogens in the animal's natural environment, the basic function of the hoof has an important role (14).
The disease is most often seen in early to peak lactation, where low-grade lesions in dry cows can quickly develop to produce raw and open lesions in early lactation (16).
1.1.2 Etiology
The precise pathogenesis of the disease remains unclear, despite more than 40 years of research. However, the presence of specific Treponema species is recognized as a major etiological component, involved in the development of the disease on feet that are suffering from cutaneous maceration (17).
Several studies have implicated Spirochetes with the etiology of DD, but in general the etiology of DD is relatively unknown. In the Lyme disease borrelia burgdorferis, spirochetes has been identified in an electron microscope to share an epitope with an unknown treponema species flagella (18). B. burgdorferis whole cell antigens, have shown to be reactive with antibodies from
10 dairy cows which are infected with DD (19). Treponema spirochetes have recently been isolated from American dairy cows with DD (20). Two distinct phenotypes were characterized by colony morphology and protein electrophoresis patterns; however, their taxonomic position is still unclear (21). Treponema phagedenis, T. denticola and T. vincentii shared the identity of five treponemal filotypes, identified by using sequence analysis of 16S rRNA genes PCR amplified from biopsy material of DD lesions by Choi et al. 1997 (21).
1.1.3 Prevalence
Approximately 20 to 25% of all cases of lameness comes from Digital dermatitis (DD), so it’s a worldwide problem in dairy herds (4).
It’s important to be able to evaluate the DD status of individual cows and whole dairy herds, in order to assess the herd's presence of digital dermatitis as well as the effect of management and treatment strategies (22).
With up to 92% of affected herds and herd prevalence ranging from 0 to 74%, DD is the most common infectious foot injury, affecting lactating dairy cows in developed countries worldwide (5).
Poor leg cleanliness at herd level (23); poor biosafety (24) indoor vs grazing housing; (11) and thus increased position time and contact with manure slurry; as well as large herd size (4) are all factors associated with higher prevalence of DD.
1.1.4 Diagnosis
Correct diagnosis of Digital Dermatitis, is especially important for controlling the disease. To optimize the effectiveness of individual topical treatments, the farmer should detect disease as soon as possible (21). At present, the diagnosis of a cow's DD status is based on visual inspection of the hooves. Most often characteristic skin damage is observed between the heels of the hind leg (11). To ascertain the cured status, or severity, of the present DD lesion, more than just assumptions about the absence or presence of the lesion are needed, since the clinical appearance may vary during the course of the disease (25).
Digital Dermatitis was previously classified according to a 5 M-step system (26), but now extends from M0, which stands for "no lesion", to M4, which stands for a chronic stage of the disease (27). As the classification is based on visual inspection of the hoof, a certain subjectivity is inevitable. Different classifications of the same lesion may vary, depending on the observer's experience, observation conditions and which tools that were used.
11 The hoof is lifted in a trimming chute for inspection and detection of DD. This examination method is the most accurate, but is also stressful for the cows and very labor intensive. It’s therefore not suitable for making frequent assessments of DD in entire herds; it’s too expensive (4), too time consuming (2) or insufficiently accurate (28). Inspection methods on standing animals have been tested.
1.1.5 Treatment
To limit the spread of infection, current control strategies aim to control the main risk factors of DD, such as unhygienic conditions and moist (23).
These strategies rely particularly on the metaphylactic collective treatments (CT) of the entire affected herd, as well as the complementary use of individual medical topical treatment of active lesions. For the farmer and the veterinary industry, both approaches present economic and environmental challenges, in addition to being time consuming (23). Antibiotic topical
administration is considered effective as individual treatments, for example oxytetracycline and lincomycin (29). However, reported for some of these products are recurrence rates as high as 50% (30). In order to decrease antimicrobial resistance and withdrawal periods for milk, the use of antibiotics should be limited.
Topical antibiotic or disinfectant at the lesion site in the individual cow, or footbaths for the whole herd, is the two levels at which treatment of DD usually occurs. Compared with untreated control cows, footbaths containing erythromycin, significantly reduced lameness within affected cows by 41%, and pain by 55%, as soon as 4 days after treatment (31).
Practices already banned by European Union policies, are the collective administration of antibiotics, and so this is no longer advised. As the standard CT in the control of DD disinfectants, such as formaldehyde and copper sulphate (CuSO4) have been used in footbaths. However, via accumulation in the soil, CuSO4 has proven to be toxic for the environment and formaldehyde is carcinogenic (32). The effectiveness of CuSO4 footbaths against DD, was shown not adequate by the evidence in a recent systematic review (29). Possible genetic resistance to copper and zinc, in microbiomes associated with DD lesions, is suggested by new evidence (32). Most CT
commercially available for the treatment of DD, are only supported by anecdotal evidence and a few by clinical trials (31). Some of the products evaluated by scientific studies, is perceived to have high variability of efficiency in practice (23). Bactericidal efficacy for most CT against DD
12 1.1.6 Impact
In many countries, DD is a serious problem for dairy producers. The disease has been
reported worldwide since it was first described in 1974 (31). Animal welfare is negatively affected by pain and lameness, which are common symptoms of DD in infected cows (3). Whether DD causes a decrease in production or not is discussed (6).
Dairy cows that were not born on the specific farm, are associated with economic and
epidemiological consequences for the spread of DD. Also, what type of floor / paving surface used on the yard. An important biosafety measure associated with reduced DD, is to disinfect hoof trimming equipment, after each cow (6).
1.2 Nutrition and milk content
1.2.1 Fat
The reproductive capacity of dairy cows, has been reported to increase with the inclusion of fat in the diet (34). This was associated with the effects of fatty acids (FA) on reproductive and hormonal systems and not just an improvement in energy balance (35).
Where reproductive efficiency is a key factor in matching calving with the season for
maximum grass growth, these effects may be important and should therefore be further investigated in such grazing systems. Reduced milk/fat concentration, lowered ruminal pH, reduced digestibility of ruminal fiber, reduced acetate / propionate ratio and increased risk of ruminal acidosis are effects of feeding large amounts of grain (36). To increase energy intake and to overcome these problems arising from high amounts of grains, interest has increased in feeding supplemental fat to grazing dairy cows (37).
Some of the following benefits would theoretically apply to fat supplements:
because fat contains three times more net energy of lactation than protein- and carbohydrate-rich feeds, one could increase the energy density of the diet (38).
Reduced energy loss such as heat, methane and urine, can be expected when improving energy efficiency (39), as the mammary gland incorporates dietary FA directly into milk fat (40).
High levels of grain in the diet increase the risk of rumen acidosis and a decrease in the milk fat percentage. This can be counteracted by the addition of fat, instead of grain (41).
13 By increasing long-chain unsaturated FA, one can change the milk fat composition and
decrease saturated FA, to obtain dairy products that are more beneficial to the health of the consumer (41).
However, high levels of fed supplemental fat in dairy cows (more than 8-9% of the total dietary fat), can lead to a decrease in the concentration of protein in milk and / or fat, due to its effect on dry matter intake, and fiber feeding in the rumen (42).
1.2.2 Protein
To ensure an adequate supply of MP, which is required for maximum milk and protein production of dairy cows, producers often feed high CP diets (43).
When dietary CP was increased from 16.5 to 18.5% and from 16.1 to 18.9%, respectively, no effect of dietary CP content on DMI and milk yield was observed in dairy cows, in a study by Cunningham et. al and Leonardi (44). On the other hand, a linear increase in DMI when dietary CP increased from 15.1 to 16.7 and 18.3% was reported in a study by Broderick (45); milk yield increased from 33.0 to 34.1 kg / day, however, only with the first CP step, no further change was shown at 18.3% CP. This gave a result of lower feeding efficiency (milk / DMI) at maximum CP. Fat and protein yields also improved when dietary CP increased from 15.1 to 16.7 but not up to 18.4% CP (45). Milk protein content decreased (3.25 and 3.18%), protein yield was unaffected (1.35 and 1.34 kg / day) and dietary CP increased from 16.1 to 18.9%. However, the yield of fat and fat content, increased significantly in response to dietary CP (44). These reports and current trials are consistent with reviews by Huhtanen / Shingfield (46). In some circumstances, feeding diets with more than 17.0% CP do not improve milk yield, but about 16.0% or less CP (DM base) gives insufficient MP for maximum milk synthesis.
1.2.3 Lactose
The basement membrane of mammary epithelial cells absorbs blood glucose into the udder, where it is synthesized into lactose (47). In a lactating dairy cow, about 20% of the circulating blood sugar is converted to lactose (48). Lactose contributes to the balance of the blood-milk barrier, along with certain minerals (Na, K and Cl), it is the main osmotic regulator between the blood and the alveolar lumen.
Actually, lactose determines the volume of milk produced, by the amount of water absorbed in the alveoli (49).
LP are positively correlated with glycemia and energy balance in cows (50), especially in high-producing breeds (51).
14 1.2.4 Urea
Urea diffuses into fluid pools in the body, such as milk in the udder and fluid in the rumen, after being mainly formed in the liver - as a means of detoxifying ammonia from the systemic circulation (52).
A pronounced increase in total urinary excretion of N (UN) in the urine over faecal N excretion, is an effect of an increase in N intake. In general, it also results in an increased concentration of milk area N (MUN; mg N / l) (53).
Microbial breakdown of dietary protein after a meal, will cause an increase in ammonia in the blood, as it is transported here from the rumen. In the liver, ammonia is broken down into urea and gives an increase in PUN. Due to diffusion between blood and milk, the MUN concentration will also rise.
When MUN is used as an estimate of UUN, the daily variation in MUN is of interest. In practice only milk samples for MUN are obtained during milking (53).
1.2.5 Somatic Cell Count (SCC)
As a proxy for mastitis, Somatic cell count is frequently used. Research has evaluated the relationship between milk traits loss and mastitis (54).
Loose-housing systems with larger herds of cows may increase the risk of several diseases, such as lameness or claw diseases (1) as well as the incidence of subclinical mastitis (55). Both subclinical mastitis and claw diseases, have shown to be decreasing fertility risk factors (56).
1.3 Reproduction
1.3.1 Reproduction and DD
Reproductive performance and milk production often decrease in animals infected by DD, causing tremendous economic losses (6).
Compared to healthy cows it was reported that the interval between calving and conception was significantly longer in lame cows, including those with DD lesions (25). A twenty day interval increase in the calving to conception time in a Mexican dairy herd, resulted in a shorter lifespan due to reduced fertility (57).
Apart from reduced reproductive performance and decreased milk yield, DD has also been associated with increased involuntary culling rate, as well as reduced general well-being of the animals (57) .
15 1.3.2 Reproduction and production
Poor reproductive efficiency in commercial dairy herds, is associated with the physiological changes that come with high milk production (12).
Undoubtedly, low BCS in the context of increasing (NEFA, ketone bodies) or decreasing (glucose, insulin, IGF-I) circulating metabolites during nutrient breakdown, plays an important role in determining the reproductive outcome.
A suboptimal reproductive tract that cannot support normal development and/or compromised oocyte quality, can be causes of infertility in dairy cattle. However, it is difficult to understand these causes (58) (59).
The contribution of poor oocyte quality to infertility, can be proven by a variety of sources. Data on non-surgical flushing of unstimulated dairy cows, firstly suggest degeneration of a significant proportion of embryos before the blastocyst stage (60). Viable embryos recovered on days six to seven, were approximately 50% in three studies. A significant proportion of embryos are lost as early as day seven, given that the fertility rate is estimated at 85 to 95% (61).
Several studies also show that embryo transfer has higher pregnancy rates in lactating dairy cows, compared to AI (62).
Physiological concentrations of NEFA, consistent with those measured in the preovulatory follicle of postpartum lactating cows, impair the development of oocytes, even during in vitro exposure (58).
1.4 Welfare
Producers have always worried about the animals in their care and tried to keep them well-nourished and healthy, so concerns for animal welfare is nothing new.
Good welfare is largely seen as the absence of injury or illness, in the tradition of animal care. The possibility that animals suffer as a result of being kept in obviously "unnatural" conditions and generally accepted management methods, has led to a newer type of concern for animal welfare. This concern focuses on the pain and anxiety the animal may feel under these circumstances (63).
Scientific research on the welfare of cattle in order to address these issues, has flourished in recent decades (64).
Human concern for the well-being of their animals, can be divided with a focus on three broad categories: "1) the animal works well, 2) the animal is well and 3) the animal can live a reasonable natural life" (65). These three animal welfare issues overlap (66).
16 The first category applies to issues such as injury and illness, but also factors that are
unfavorable for the farm's viability, such as reproduction problems and poor growth rate.
Category number two goes a little deeper. Here you also worry about whether the animal feel hunger, fear, pain or other feelings of discomfort, but even if they experience positive conditions such as play.
For many people, such as consumers, the opportunity for animals to express a natural behavior and live a relatively natural life is of great importance - this falls into the third category (13).
A cow that has reduced mobility (natural behavior, category 3), may be in pain and lame (affective condition, category 2), and may also have poorer reproduction and lower production (category number 1). The suffering that the animal undergoes due to illness, causes a lot of concern from an animal welfare perspective. In these cases, improvements of one aspect, for example increased availability of natural behavior / freedom of movement, also improve the other aspects (feelings of discomfort and possibly also reduce pain) (66).
Figure 1. Three overlapping areas of welfare concern (65).
An animal that is "healthy, comfortable, well-nourished, safe, can express innate behavior and does not suffer from unpleasant conditions such as pain, fear and distress" is classified by the World Organization for Animal Health as an animal in good animal welfare (13).
17
2. METHODOLOGY
2.1 Study design
Figure 2. Research construction (source: Lina M. E. Lundholm)
This thesis was carried out at the Lithuanian University of Health Sciences, Tilžės Veterinary Academy 18, Kaunas and from dairy cows in Kedainiai.
20 cows were used for the statistical part of the thesis, 10 cows were healthy (control group) and 10 cows were diagnosed with digital dermatitis and were clearly lame. To define the calving individual's age and lactation time, three subclasses were used.
The cows were observed, and productivity data were recorded and evaluated from three specific times: (December 2019, January 2020, February 2020).
Analysis of the milk was done once a month during milking both in the morning and in the evening. During both milking times, the amount of milk was checked and noted. Milk samples were taken one month in the morning and the following month in the evening.
The milk parameters from December 2019, January 2020 and February 2020, were assessed using a lab for milk analyses.
18 The primary information collected is systematized, grouped, analysed, and presented in SPSS and to some extent also in the Microsoft Excel 20.
Mathematical statistics were used, to process the obtained research results and the interpretation of the obtained data.
The paper presents the following statistical indicators: arithmetic mean and its error, standard deviation, minimum (Min), maximum (Max) and statistical reliability indicator - Student's t-criterion with significance level P <0.05: when P <0.05 - differences between the two comparison groups is considered statistically significant at 95.0% reliability level; when P> 0.05, differences between groups are considered statistically unreliable (not statistically significant).
2.2 Laboratory used for analysis of milk samples
Using the middle infrared detector LactoScopeFTIR, the amount of fat, lactose and urea was analysed. The number of somatic cells was classified using a Somascope detector, which works with the flow cytometry principle. The content of the milk was classified by PE "Pieno tyrimai".
2.3 Requirement to qualify for the study
The cows used in our statistic study, where all cows of Simmental/Holstein mix. They are all in a close age range and all of them where multiparous cows in their last three months of lactation. The study group where confirmed clinically ill with digital dermatitis and the control group where all clinically healthy, in January 2020.
19
3. RESEARCH RESULTS
3.1 DD effects on milk production
Digital dermatitis effects on milk yield traits are showed in Fig. 3; In December there was no noticeable difference with healthy group producing 0.18 kilograms more milk in comparison to DD cows, in January and February the difference becomes noticeable, with the healthy cows producing 2.27 kilograms more then compared to DD cows. The difference, however, is not significant enough to attribute it to the disease.
Fig.3 milk yield kg
As outlined by the data below cattle with digital dermatitis do not see a statistically significant decrease in milk yield (Table 1), but there is a slight decrease none-the-less.
Table 1. milk yield, kg
Cows St. Error P value Milk kg., December Healthy cows 1.4076 p=0,961
DD cows 3,3076
Milk kg., January Healthy cows 1,2073 p=0,217 DD cows 1,2988
Milk kg., February Healthy cows 2,2611 p=0,371
DD cows 2,4311
Association between DD cows and healthy cows for 90 days milk production Difference is significant if p < 0,05. 0 5 10 15 20 25 30
2019 Desember 2020 January 2020 February
Milk Yield, kg
20
3.2 Digital dermatitis effects on milk fat
Digital dermatitis effects on milk fat yield traits are showed in Fig. 4; This is emphasized by December showing a slight increase in fat content by 0,515 perc. compared to the healthy cows, while in January the healthy group displayed a slight increase by 0.436 perc. and finally, both groups had roughly identical fat content in February. Meaning that digital dermatitis has no apparent impact on milk fat content.
Fig.4 milk fat yield perc.
As outlined by the data below DD cows do not show a statistically significant decrease in milk fat content (Table 2).
Table 2. Fat proc.
Cows St. Error P value Milk fat proc.,
December
Healthy cows 0.2706 p=0,548 DD cows 0.5099
Milk fat proc., January
Healthy cows 0.3825 p=0,327 DD cows 0.2032
Milk fat proc., February
Healthy cows 0.3489 p=0,699 DD cows 0,2664
Association between DD cows and healthy cows for 90 days milk production
21
3.3 Digital dermatitis effects on milk protein
Digital dermatitis effects on milk protein yield traits are showed in Fig. 5; This is emphasized by December showing a slight increase in milk protein content by 0.028 perc. compared to the DD cows, while in January the DD group displayed a slight increase by 0.198 perc. and finally, the healthy group had slightly increased protein content in February by 0,182 perc. meaning that digital dermatitis has no discernible impact on milk protein content.
Fig .5 milk protein yield proc.
As outlined by the data below (Table 3) cattle with digital dermatitis do not show a statistically significant decrease in milk protein content.
Table 3. Protein proc.
Cows St. Error P value Milk protein proc.,
December
Healthy cows 0.1444 p=0,220 DD cows 0.1217
Milk protein proc., January
Healthy cows 0.0679 p=0,253 DD cows 0.1539
Milk protein proc., February
Healthy cows 0.0555 p=0,220 DD cows 0,1274
Association between DD cows and healthy cows for 90 days milk production Difference is significant if p < 0,05.
22
3.4 Digital dermatitis effects milk lactose
Digital dermatitis effects milk lactose yield traits are showed in Fig. 6; This is emphasized by the December and January data which shows that both groups had roughly equivalent milk lactose content, only in February is there any noticeable difference with the healthy group having slightly increased by 0.142 perc. milk lactose content. Meaning that digital dermatitis has no discernible impact on milk lactose content.
Fig .6 milk lactose yield proc.
As outlined by the data below (Table 4) cattle with digital dermatitis do not show a statistically significant decrease in milk lactose content.
Table 4. Lactose proc.
Cows St. Error P value
Milk lactose proc., December
Healthy cows 0.0463 p=0,779
DD cows 0.0431
Milk lactose proc., January
Healthy cows 0.0507 p=0,970
DD cows 0.0908
Milk lactose proc., February
Healthy cows 0.0713 p=0,380
DD cows 0,0474
Association between DD cows and healthy cows for 90 days milk production
Difference is significant if p < 0,05. 0 1 2 3 4 5 6
2019 Desember 2020 January 2020 February
Milk lactose yeald, perc.
23
3.5 Digital dermatitis effects on milk urea
Digital dermatitis effects on milk urea mg/100ml. are showed in Fig. 7; This is emphasized by December showing a slight decrease by 1.6 mg/100ml in urea content compared to the healthy cows, while in January and February the healthy group displayed a slight decrease compared to the group with digital dermatitis. Meaning that digital dermatitis has no discernible link with milk urea content.
Fig. 7 milk urea mg/100ml.
As outlined by the data below (Table 5) cattle with digital dermatitis do not show a statistically significant decrease in milk urea content.
Table 5. Urea
Cows St. Error P value
Milk urea mg/100ml. December Healthy cows 0.7520 p=0,130 DD cows 0.6708 Milk urea mg/100ml. January Healthy cows 1,0000 p=0,138 DD cows 1.1647 Milk urea mg/100ml. February Healthy cows 7,5564 p=0,396 DD cows 5,1146
Association between DD cows and healthy cows for 90 days milk production
Difference is significant if p < 0,05. 0 5 10 15 20 25 30
2019 Desember 2020 January 2020 February
Urea mg/100ml
24
3.6 Digital dermatitis effects on milk SCC
Digital dermatitis effects on milk SCC thousand cells/ml are showed in Fig. 8; however, a slight increase was still present. During the three-month trial the group with digital dermatitis had consistently lower, albeit not significantly, somatic cell count per millilitre with it being the least noticeable in December and the most obvious in February. Though the relatively small difference points to the decrease not being tied to digital dermatitis.
Fig. 8 milk SCC thousand cells/ml
As outlined by the data below (Table 6) cattle with digital dermatitis do not show a statistically significant difference in somatic cell count.
Table 6. Somatic Cell Count
Cows St. Error P value
Milk SCC count thousand cells/ml., December
Healthy cows 25.7647 p=0,863
DD cows 14.5718
Milk SCC count thousand cells/ml., January
Healthy cows 34.0218 p=0,840
DD cows 30.1864
Milk SCC count thousand cells/ml perc., February
Healthy cows 18.5833 p=0,555
DD cows 12.9792
Association between DD cows and healthy cows for 90 days milk production
Difference is significant if p < 0,05. 0 20 40 60 80 100 120 140
2019 Desember 2020 January 2020 February
SCC, thousand cells/ml
25
3.7 DD effects on reproduction traits
Digital dermatitis effects on cow’s reproduction traits table 7. Judging by the number of the inseminations which were successful, with the exception of one of the sick cows, which was not related to digital dermatitis, but an unrelated issue with its reproductive system we can conclude that digital dermatitis does not influence the reproduction of affected animals in our chosen time frame.
Table 7. DD effects on reproduction traits
Cow Number Easy to detect heat First insemination Second insemination Third insemination One calf No calf DD cowS 8 10 3 3 9 1 Healthy cow 6 10 4 1 10 0
80% of the cows with DD was easy to detect heat on while 60% of the healthy cows had an easily detected heat. Moreover 30% of cows with DD was inseminated a third time while 10% of the healthy cows was inseminated a third time. 90% of the cows with DD got one calf, and 10% never got any calf. 100% of the healthy cows got one calf.
26
4. DISCUSSION OF RESULTS
Despite claw disease currently being the third most severe bovine disorder, after mastitis and reproductive disorders(67) the exact cause of DD is not completely clear. There have, however, been findings suggesting bacterial causes (68); though there is a glaring lack of insight into the complexity of said bacteria.
The consequences of the lack of interest in this topic are not only economic but, also in the animal's welfare. Effective and expedient treatment can only be developed once all the repercussions of an affliction are fully understood -which points to a severe need for further study.
4.1.1 Milk yield
In our study group, no statistically significant changes were seen, but a variety of studies show the opposite.
Warnick et al. (2001) (69) found that afflicted cows produced consistently less milk (upwards of 1.5 kg less per day) than healthy cows, which correlates with Amory et al. (2008) (70) who found that milk yield slightly increases after DD treatment. This suggests that DD did impede the milk production of affected cows. By Green et al. (2002) (71) estimations, the reduction would be upward to 360 kilograms over a 305-day timespan.
4.1.2 Fat
In our study group, no statistically significant changes were seen, but fat content mirrors important factors due to some studies.
The reproductive capacity of dairy cows, has been reported to increase with the inclusion of fat in the diet (35).
By increasing long-chain unsaturated FA, one can change the milk fat composition, and decrease saturated FA, in order to obtain dairy products that are more beneficial to the health of the consumer (40).
However, high levels of fed supplemental fat in dairy cows (more than 8-9% of the total dietary fat), can lead to a decrease in the concentration of protein in milk and / or fat, due to its effect on dry matter intake, as well as fiber feeding in the rumen (42).
4.1.3 Protein
27 An important role in payment of milk is the protein content. It also plays a role in determining the breeding value of cows (72). To ensure an adequate supply of MP, which is required for maximum milk and protein production of dairy cows, producers often feed high CP diets (43).
4.1.4 Lactose
In our study group, no statistically significant changes were seen, but other studies show its importance. Actually, lactose determines the volume of milk produced, by the amount of water absorbed in the alveoli (49).
LP are positively correlated with glycemia and energy balance in cows (50), especially in high-producing breeds (51).
4.1.5 Urea
In our study group no statistically significant changes were seen, but urea is a valuable variable in other investigations.
Urea diffuses into fluid pools in the body, such as milk in the udder and fluid in the rumen, after being mainly formed in the liver -as a means of detoxifying ammonia from the systemic circulation (52).
MUN is used as an estimate of UUN, the daily variation in MUN is of interest, in practice only milk samples for MUN are obtained during milking (53).
4.1.6 Somatic Cell count
In our study group, no statistically significant changes were seen.
As a proxy for mastitis, Somatic cell count is frequently used. Research has evaluated the relationship between milk traits loss and mastitis (54).
Both subclinical mastitis and claw diseases, have shown to be decreasing fertility risk factors (56).
4.1.7 Reproduction
The link between affliction and consequences during reproduction and lactation, have been documented in depth (73). In particular for digital dermatitis it was reported that the hazard ratio of conception for cows with DD and mixed lesions (digital dermatitis and claw lesions) was 0.71 and 0.31, respectively (25).
28
CONCLUSION
• The mean difference for milk yield between cows with digital dermatitis and healthy cows, was not statistically significant (p>0.05)
• The mean differences of milk quantity parameters (fat, protein, lactose, urea) between healthy cows and cows with digital dermatitis, were not statistically significant (p>0.05).
• The mean differences of milk quality parameters (Somatic cell count) between healthy cows and cows with digital dermatitis, were not statistically significant (p>0.05).
• In reproduction it could be concluded that no outstanding differences was seen.
• The statistical part of this particular study suggests there are no correlation between digital dermatitis and milk yield, or milk parameters.
29
SUGGESTIONS/RECOMMENDATIONS
• First suggestion, to increase the statistical significance for future research, could be to increase the time span over which the data is collected. However, this might only work if the cows with digital dermatitis remains untreated, all the affected cows in our study group were treated in January 2020.
• Second suggestion, to use a larger number of animals could increase the statistical significance, since it would give a better basis to build a case on.
• Last but absolutely most important, always treat Digital Dermatitis as a serious threat to the animal’s welfare and give the animal adequate care and treatment.
30
ACKNOWLEDGEMENT
First and foremost, I would like to express my sincerest gratitude to Kristina De Witte for being my supervisor. Kristina’s support, patience, and knowledge as well as motivation throughout writing this master thesis, have been of great valuable to me. I could not imagine a better mentor for my final thesis.
Apart from my supervisor, I would like to thank Erven and Marius for help with milk sampling, information about the cows and input on results, without which my thesis would not have been possible. I also want to thank Malin Sköld for being such a great English teacher and friend who took of her spare time to proofread this thesis.
Finally, I would like to devote my last acknowledgement to my family and friends for their love and support, without whom I would not even made it this far.
31
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