Evaluation of hydrated lime as a cubicle bedding material on the microbial count on teat skin and new intramammary infection
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Irish Journal of Agricultural and Food Research 52: 159–171, 2013
Evaluation of hydrated lime as a cubicle bedding
material on the microbial count on teat skin
and new intramammary infection
D. Gleeson†
Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland
In two experiments, the effect of applying hydrated lime as a cubicle bedding material
on the microbial count on teat skin and new intramammary infection were evaluated.
In experiment 1, dry dairy cows (n=60) were assigned to one of three cubicle bedding
treatments for a 5 week period. The treatments applied were: Hydrated lime (HL), HL
(50%) + Ground limestone (50%) (HL/GL) and GL. In experiment 2, two teat disin-
fectants products chlorhexidine (CH) and iodine (I) were applied to teats at milking in
conjunction with two cubicle bedding materials with lactating cows (n=60) for a six-
week period. The treatments applied were: HLCH; HLI; and GLI. The HL treatment
had significantly more teats (P160 IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 52, NO. 2, 2013
Introduction or shaving bedding to control bacte-
Mastitis represents a major economic cost rial populations (Fairchild et al. 1982).
to dairy farmers with losses of up €60 per Increasing the pH of cubicle bedding can
cow for the average milk supplier (O’Brien suppress bacterial growth (Kupprion et al.
2008). As bulk tank milk somatic cell 2002). Hydrated lime is an alkaline com-
count (BMSCC) increased, from ≤100,000 pound that can create pH levels as high
to >400,000 cells/mL, the net farm profit as 12.4. At levels greater than 12, the cell
generated decreased by €19,504 for the membranes of pathogens are considered
average Irish dairy farmer (Geary et al. destroyed (Chettri 2006). A one hundred-
2012). Milk loss due to subclinical mastitis fold decrease in bacterial numbers has
can also contribute to these overall farm been reported when HL was added to
losses (Hogeveen, Huijps and Lam 2011). recycled manure as a cubicle bedding
Staphylococcus aureus is one of the major (Hogan et al. 1999). However, anecdotal
and more virulent pathogens that can evidence suggests that the use of an iodine
cause mastitis infection and lactating cows based post-milking teat disinfectant in
are one of the main reservoirs of this spe- conjunction with the use of hydrated lime
cies. Moreover, S. aureus colonisation of can have a negative effect on teat condi-
teat skin increased the risk of intramam- tion. Long-term changes in teat condition
mary infection (IMI) (Myllys et al. 1993; generally occur over a period of 2 to 8
Roberson et al. 1994). It was suggested that weeks (Neijenhuis et al. 2000). The condi-
by minimising the exposure of teat ends to tion observed is generally referred to as
microorganisms, the rate of environmen- teat hyperkeratosis (Shearn and Hillerton
tal infection levels were reduced (Smith, 1996) and this condition can be exacerbat-
Todhunter and Schoenberger 1985). ed by disinfectants (Rasmussen 2004) or
During a cow housing period, bedding cold harsh weather (Timms, Ackermann
materials such as sawdust, lime and sand and Kerlhi 1997). Medium-term changes
are applied to cubicles to help to maintain to the teat barrel generally become vis-
a clean dry cubicle bed. By minimising ible within a few days or weeks of a man-
pathogen growth within the bedding mate- agement issue or environmental factors
rial, lower numbers of pathogens were occurring (Ohnstad et al. 2007). These teat
transmitted onto the cow’s teats, thereby changes include petechial haemorrhages
reducing the possibility of IMI (Kudi, Bray or larger hemorrhaging of the teat skin
and Niba 2009). However, materials of a (Hillerton, Middleton and Shearn 2001).
fine particle size such as sawdust may sup- Other changes include cracking or chap-
port rapid growth of bacteria and can lead ping of the teat skin (Hillerton et al. 2001).
to high populations of bacteria on teats. There is little knowledge on the effect
Zdanowicz et al. (2004) demonstrated a of using HL as the sole cubicle bedding
correlation between environmental bac- material on bacterial numbers on teats, on
terial counts on teat ends with bacterial teat condition and on IMI. The objectives
counts in sawdust bedding, which can cre- of this study were 1) to establish if dry
ate an environment for IMI (Hogan et al. dairy cows housed in cubicles which were
1999). However, some bedding materials bedded using HL would have a reduced
like sand can minimise pathogen growth teat microbial count, lower new intramam
(Kudi et al. 2009). Hydrated lime (HL; mary infections, have a better California
calcium hydroxide) has been added to Milk Test (CMT) result post-calving and
other bedding materials such as sawdust have lower somatic cell counts (SCC)Gleeson: Hydrated lime as a cubicle bedding material 161
for a three week period post-calving, period before calving and for a three week
compared to cows bedded with the com- period post-calving. Milk samples for both
monly used ground limestone (GL) and Experiments 1 and 2 were examined using
2) to establish if lactating dairy cows International Dairy Federation guidelines
housed in cubicles which were bedded for microbiological analysis (IDF 1981).
using HL combined with two contrasting
teat disinfectant products would have less Bacterial counts on teats
intramammary infections, lower SCC and On the start date and once weekly there
more teat skin irritation as measured by after, all teats from each cow in each group
teat-end hyperkeratosis and ‘medium term were swabbed using one sterile swab per
teat changes’, compared to cows bedded cow (Cultiplast, Milan, Italy), before teat
with the commonly used GL. preparation for milking. The sterile swab
was rubbed across the teat orifice and
down the side of each teat avoiding con-
Materials and Methods tact with the udder hair or cows flank.
Experiment 1 Swabs were then placed in individual ster-
Three cubicle bedding materials contain- ile bottles containing 5 mL of Tryptic Soy
ing (i) Hydrated lime (HL), (ii) HL (50%) Broth (Becton-Dickinson, Sparks, USA).
+ Ground limestone (50%) (HL/GL) and The broth was prepared in 500 mL vol-
(iii) GL were applied to three separate umes and autoclaved at 121 °C for 15 min,
cubicle houses for a five week period. Sixty and then distributed into 5 mL aliquots
dry Holstein Friesian dairy cows were in a Laminar Flow Cabinet. The sterile
randomly assigned to one of three houses bottles containing the swabs were frozen
based on their expected calving date and (-20 °C) until analysed for the presence of
lactation number. Staphylococcus and Streptococcus bacteria.
Cubicle houses contained a central slat- The swabs were streaked across two sepa-
ted passage with a single cubicle space rate selective agars: Baird Parker (+ egg
allocation per cow and similar feed space yolk emulsion 50 mL/l) (Staphylococcus)
per group. Cubicles were bedded once and Edwards (+ 6% sterile bovine or
daily with sufficient material to leave a sheep blood) (Streptococcus). Following
dry surface with no cubicle matt visible. incubation at 37 °C for 24 h, microbi-
Cows remained on the cubicle bedding al counts for each pathogen type were
material until calving (mean of 5 weeks manually estimated and assigned to one
dry period per cow) and then were man- of four categories depending on bacte-
aged outdoors on grass. Individual quarter rial numbers present. (0=no pathogen
milk samples were taken post-calving and present, 1162 IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 52, NO. 2, 2013 of the three cubicle bedding treatments limestone rock which is used to soak up based on individual cow milk SCC (aver- moisture on cubicle mats or concrete. The age of three previous weeks), lactation pH of this product is approximately 8–8.5. number, days in milk (120) and teat hyper- keratosis score. Cows assigned to one HL Milk sample analysis cubicle house and the GL house were pre Individual quarter milk samples were and post sprayed at milking with an Iodine taken at the start date and at day 42 based (0.5%) teat disinfectant, HLI and and bacterial pathogens were iden- GLI, respectively. Cows assigned to the tified as 0=no pathogens present, 1= second HL cubicle house were pre and Staphylococcus aureus, 2=Non-haemolytic post sprayed at milking with a chlorhexi- Staphylococcus, 3=Streptococcus dysga- dine-based (Deosan Teatfoam, Diversey lactiae, 4=Streptococcus uberis. Quarters Hygiene Sales Limited, Jamestown Rd, with an SCC>500×106 cells/mL at the Finglas, Dublin 11) teat disinfectant start date were considered sub-clinically (HLCH). Pre-milking teat preparation infected and were excluded from this par- included washing teats with running water, ticular data set. followed by the application of the relevant Individual cow milk samples were col- teat disinfectant and then drying with an lected weekly using electronic milk meters individual paper towel for each cow. The (Dairymaster, Tralee, Co Kerry, Ireland) average daily milk yield per cow over the and analysed for SCC. Bulk milk samples test period was 23 kg per cow per day. with an SCC >500×106 cells/mL at the Treatment groups (n=20) were allocated start date were considered sub-clinically separate cubicle rows which contained a infected and were excluded from this slatted passageway with a single cubicle data set. The number of cows excluded space allocation per cow, similar feed for analysis was 2, 3 and 3 for HLI, space per group and remained indoors HLCH and GLI, respectively. Individual for the duration of the experiment. All quarter and bulk milk samples were ana- cubicles were fitted with rubber mats. lysed using a Somacount 300 (Bentley Cubicles were bedded with the manufac- Instrument Company Limited, Dublin 12, turer specification rate for HL (170 g per Ireland). cubicle) twice daily and this was applied to the back one-third of the cubicle. Higher Teat condition application rates than that specified are All four teats of each cow were visu- considered unnecessary due to the drying ally scored on three occasions (day 1, properties of HL and the possibility of day 21 and day 42) by the same operator deterioration in teat condition. This HL using a simplified classification system for product (White Rhino) is marketed as the evaluation of hyperkeratosis (HK) having a pH of 12.4 that can inhibit bacte- in bovines (Neijenhuis et al. 2001). The rial growth. classification scores were: Score1=normal Cubicles bedded with GL received a teat-end orifice; Score2=slight smooth or more liberal application (approx 300 g broken ring of keratin; Score3=moderate per cubicle) twice daily, which is typical raised smooth or broken ring of keratin; of rates normally applied for this prod- Score4=large raised smooth or broken uct on farm. Ground limestone (Agrical, ring of keratin. Teats were scored directly Nutribio Ltd, Tivoli Industrial Estate, after milking, with the help of artificial and Cork, Ireland) is milled and crushed light to illuminate teat ends and the score
Gleeson: Hydrated lime as a cubicle bedding material 163
totaled and averaged for each cow for the treatments for SCC and teat hyperkera-
purposes of analysis. tosis score at each measurement day and
Teat barrels were also inspected by the when data were pooled over the total mea-
same operator at the start date and on five surement period. Interactions for time and
occasions thereafter for medium-term teat treatment x time were also tested. A t-test
changes. Teats were scored for these con- was used to measure changes in quarter
ditions by visual assessment using a simple somatic cell count from day 1 to day 42 for
classification system as recommended by each individual treatment. Differences in
Mein et al. (2001) for assessing these bacterial numbers observed on cow’s teats
conditions; Score1=Normal teat (smooth, were measured using Fisher’s exact test.
soft, healthy skin), Score2=Dry skin (red- Where there was an effect of treatment a
dened or blue skin, flaky or rough skin pair-wise comparison was conducted.
with minimum cracking) and Score3=
Open lesions (chapped, cracked).
On the start date and once weekly
thereafter, all teats from cows in groups Results
GLI and HLI were swabbed to measure Experiment 1
bacterial numbers using the same tech- There were no differences observed in the
nique and method of analysis as applied in number of quarters classified for a CMT
experiment 1. score of 1 or >1 or for pathogens pres-
ent in milk samples at calving between
bedding treatments (Table 1). There were
Statistical Analysis no significant differences observed for
Statistical analysis of data was performed BMSCC between treatments at weeks 2, 3
using SAS software (SAS 2011). Cows and 4 post calving. The average BMSCCs
were blocked in pairs according to lacta- over the trial period were 92,000, 60,000
tion number and expected calving date and 74,000 cells/mL for HL, HL/GL and
for experiment 1 and on the average GL, respectively. There was one clinical
BM SCC (previous three weeks), days in case for each of HL and GL treatments
milk and teat-end hyperkeratosis score for over the four week lactating period.
experiment 2. The statistical model was a There were no significant differences
mixed model with cows/blocks as the ran- in teat bacterial numbers between treat-
dom effect and bedding treatment as the ments for experiment 1 and 2 on day
fixed effect and with repeated measures 1. Numbers of both Staphylococci and
over time. Comparison was made between Streptococci observed on teats reduced
Table 1. Number (%) of quarters with low (1) and high (≥2) California Mastitis Test scores at calving -
Experiment 1
California California No. quarters
Mastitis Test1 (%) Mastitis Test (%) with pathogens
Bedding material No. of quarters 1 ≥2
Hydrated lime 55 48 (87) 7 (13) 1
Hydrated/Ground limestone 76 69 (91) 7 (9) 1
Ground limestone 67 66 (98) 1 (2) 3
1California Mastitis Test Score: 1=200,000 cells/mL and ≥2=150,000 to 5,000,000 cells/mL.164 IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 52, NO. 2, 2013 during the measurement period regardless differences between bedding treatments or of the cubicle bedding material applied. within treatments at day 1 (start day) or at When swab counts for each measure- day 42 (finish day) (P>0.05). The average ment day were pooled, the HL treat- quarter SCC on day 1 was 29,000, 34,000 ment had more teats with no Staphlococci and 21,000 and on day 42 was 35,000, 41,000 present compared to GL and had less and 39,000 cells/mL for HLI, HLCH and teats with ‘numerous’ bacteria (11
Gleeson: Hydrated lime as a cubicle bedding material 165 respectively. The percentage of quarters tissue observed in all cases were considered with an SCC greater than 200,000 cells/mL mild (score 2) and in the majority of cases increased (5%) with the GL bedding treat- were transient in nature. Changes observed ment compared to day 1. However, the per- included partial redness of the teat barrel centage of quarters with an SCC>200,000 and minor cracking of the teat skin. In two
166 IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 52, NO. 2, 2013
2.4
HLI HLCH GLI
2.3
2.3 2.25 2.25
2.2 2.2
2.2
Teat score (1–4)
2.1
2.1
2
2.0
1.93 1.93
1.9
1.8
1.7
1 2 3
Observation times
Figure 1. Average teat hyperkeratosis score on day 1, 21 and 42 – Experiment 2.
HLI=Hydrated lime + Iodine, HLCH=Hydrated lime + Chlorhexidine, GLI=Ground
limestone + Iodine.
first observation day compared to the sub- The percentage of teats within four
sequent two observation days (PGleeson: Hydrated lime as a cubicle bedding material 167 teats prior to teat preparation for milking periods probably indicates an effect of at each observation day (Figure 2). The improved management for all cubicles percentage of teats with no Staphylococci during the test period. As cubicle bedding present was higher (P
168 IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 52, NO. 2, 2013 further of new intramammary infection. While all treatments had low SCC lev- Satisfactory teat preparation (Gleeson et els, the HLCH treatment had the lowest al. 2009) prior to milking in experiment level at most tests days during the study. 2 also nullified differences in teat bacte- The HLCH treatment was also observed rial numbers between treatments, as teat to have the lowest percentage of cows swabbing was conducted prior to teat (9%) with a SCC>100k compared to the preparation and this may also account HLI (14%) and GLI (19%) during the for no differences in new intramammary study. This may indicate a positive benefit infection between treatments. Very low of disinfectant type rather than bedding bacterial levels on teats could be expected material. Furthermore, the average quar- after teat disinfection as compared to ter SCC was low at the trial start date and levels taken before disinfection (Kristula good management practices such as regu- et al. 2008). In Experiment one, the SCC lar maintenance of the cubicle beds and levels recorded and the number of clini- teat preparation prior to milking, were cal cases observed during the period post important factors in maintaining low SCC calving were low for all bedding treat- levels and new infection rates for all treat- ments. In this experiment, cows were ments throughout the study. The milking grazed outdoors from calving and this process through improper milking time, management strategy may account for the hygiene and machine function can contrib- low SCC and new infection levels record- ute to new infection rates when bacteria ed. Environmental factors can influence are present (National Mastitis Council the microbial populations on teats ends 1996; Galton, Petersson and Merrill 1988). (Rendos, Eberhart and Kesler 1975). While the HL treatment had lower bacte- Higher SCC levels have been reported rial numbers on teats when presented for during the months where cows are nor- milking, all teats were prepared (washed, mally housed indoors (Nov to March) disinfected and dried with individual paper with SCC reducing during the summer towels) prior to cluster application and period corresponding to when cows are this may have partially nullified the benefit grazed outdoors (Berry et al. 2006). The of the bedding material as teat prepara- benefits of any carry over effect of the tion has been shown to reduce teat bac- bedding material from the housed period terial numbers (Gleeson et al. 2009) and pre-calving were not evident. in particular environmental Streptococcal In Experiment two, an increase in the infections (Pankey et al. 1989). Should teat number of quarters with sub-clinical infec- preparation be omitted/less rigorous, as in tions was observed for the non-hydrated the case on many dairy farms in Ireland, lime bedding treatment compared to the differences in new infection rates may start date and this may be partially due to have been observed. the cows remaining indoors for the dura- There were no differences in ‘medium tion of this study. The percentage of GLI term’ teat changes between the two hydrat- quarters with a sub-clinical infection was ed lime treatments; however the GLI bed- 1.9% higher than HLCH and 3.4% higher ding treatment had a lower number of teat than HLI. However, this increase in sub- tissue changes during the study. Previous clinical infections during the trial period studies by Kristula et al. (2008) indicated could be related to the high percentage that the application of HL at a rate of of cows with bacteria present in quarters 0.5 kg per cubicle every 48 h caused an on day 1. irritation to skin, udder and legs of cows,
Gleeson: Hydrated lime as a cubicle bedding material 169
with some lesions evident approximately the hydrated lime treatments. A larger
3 days after exposure to HL. There were no number of study animals and a longer test
lesions to udder and legs in this study and period may be necessary to show a signifi-
only minor ‘medium term teat changes’, cant effect of HL in terms of reduced new
even though the application rate for HL infection rates. Hydrated lime could be
was higher (340 g/day) compared to that successfully used as cubicle bedding mate-
applied by Kristula et al. (2008). The appli- rial for dairy cows if used at the recom-
cation of HL on four occasions instead of mended rates with either CH or I based
one in 48 h may also have influenced this teat disinfectants.
outcome. Furthermore, it was suggested
by Kristula et al. (2008) that stall designs
that allow more manure to be deposited Acknowledgements
on the back end of the cubicle mattress The author wishes to thank John Paul Murphy
and Jimmy Flynn for their technical assistance
may also exacerbate the irritation prob-
and the staff of the dairy unit at Teagasc, Animal
lem. Cubicles in this present study were & Grassland Research and Innovation Centre,
cleaned down twice daily when the lime Moorepark, Fermoy, Co. Cork for their help in car-
was applied. ing for the cows.
The percentage of teat changes for all
treatments were much lower than +5% References
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