Teat end and skin condition is an important property that is impacted by a variety of factors including the milking machine, weather, bedding, and physiological status. Teat dipping is employed primarily to aid in the prevention of new infections but is also an opportunity to improve teat condition. Teat condition or teat tolerance studies are a required part of medicinal product registrations. The aim of this paper is to discuss the formulation variables that may positively or adversely impact teat condition and to review some of the available clinical data. This information should help dairy producers and advisors in making judgements about product selection and product claims relating to teat conditioning.
BACKGROUND
Preservation of healthy teat skin is important in maintaining a natural defense against infection. Improvement or maintenance of teat condition is important to the dairy producer because it can impact: bacterial colonization of skin, milk let-down, milk-out time, milking speed and parlor through put. Fox has shown a correlation between teat skin condition and colonization of skin by St. aureus (Fox, 1991). It is accepted that rough or chapped skin will provide more places for bacteria to attach and survive. An impact on udder health and mastitis can be anticipated. McKinzie has shown an impact of teat skin condition on milk yield and milk out time (McKinzie and Hemling, 1995). In this study, teats were intentionally chapped then dipped at each milking with an emollient iodine post dip. Milking was done in a Double 6 (12 unit) DeLaval herringbone parlor with automatic cluster removal. Teat condition was evaluated daily against milk production (seven day rolling total) and milk-out time (Graph 1 and Graph 2). When teats had the worst teat condition, milk yield was lowest and milk-out time was highest. As teat condition improved, milk yield increased and milk-out time decreased. Decreased milking time and increased milk yield provide additional economic incentive to maintain healthy teat condition.
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Graph 1. Teat Condition milk yield
Graph 2. Teat condition milk-out time
Formulation variables
Teat tips are provided in a variety of product types in an even broader array of formulations. Product types include: post dips, pre-dips, post or pre-dip concentrates, foaming dips, winter dips and barrier dips. Table 1 shows some of the performance requirements for the main classes of teat dip. It should be noted that teat conditioning is extremely important for all types of post dips. It is somewhat less important for pre-dips/udder washes because of the shorter contact time.
Table 1. Preferred characteristics of teat dips
|
Pre Dip(Udderwash) |
Post Dip |
Post DipBarrier |
Post Dip
Concentrate |
| Germicidal Broad Spectrum |
Critical |
critical |
critical |
Critical |
| Speed of Kill |
Critical |
important |
important |
Important |
| Non Irritating |
Desirable |
critical |
critical |
Critical |
Promotes Healing
(Added Emollient) |
Beneficial |
desirable-critical |
desirable-critical |
desirable-critical |
Promotes Healing
(Added Emollient) |
Beneficial |
desirable-critical |
desirable-critical |
desirable-critical |
| Good Wetting |
Critical |
desirable |
desirable |
Desirable |
| Viscosity |
Low |
low-moderate |
high |
low-moderate |
| Stability - Germicide |
Critical |
critical |
critical |
Criticalconc. & RTU |
| Stability - Physical |
Critical |
critical |
critical |
Critical conc. & RTU |
| Residual Efficacy |
Unwanted |
desirable |
critical |
Desirable |
| Persistent Physical/Chemical |
Unwanted |
desirable |
critical |
Desirable |
| Detergency |
Desirable |
not important |
not important |
not important |
| Milk Residue |
Critical |
critical |
critical |
Critical |
| Other |
|
|
|
defined reconstituted water compatibility & stability
|
Teat dips are formulated with a broad range of germicides as shown in Table 2. Although there are some general trends about the impact of various germicides on teat condition, the major results are formulation dependent. The exceptions may be sodium hypochlorite (referred to as chlorine or bleach), which is a strong oxidizer and cannot be pre-formulated with emollients, and certain acid germicides, which require a low pH </= 3 for germicidal activity. As Table 2 indicates, iodine is the most common germicide used in teat dips, and we will use it as a primary example to review formulation variables that impact teat condition.
Table 2. Teat dip germicide – Estimated market share**
| GERMICIDE |
TYPE |
US |
AMERICAS & PACIFIC |
EUROPE*** |
|
Iodine |
Oxidative |
70 |
60-70 |
45
|
|
Chlorhexidine |
Non-oxidative |
10 |
10 |
25 |
|
Peroxide |
Oxidative |
7-8 |
5 |
5 |
|
Chlorine Dioxide |
Oxidative |
7 |
4-5 |
5 |
|
Bleach (chlorine) |
Oxidative |
4 |
10-15* |
5 |
|
DDBSA |
Non-oxidative |
1-2 |
2 |
10 |
|
Lauricidin |
Non-oxidative |
1-2 |
1-2
|
|
|
Nisin |
Non-oxidative |
1-2 |
<1 |
|
|
Others |
|
|
|
5 |
*Brazil 50%
** DeLaval estimates
*** UK Iodine = 60-65%, DDBSA = 5%
With over 100 iodine teat dips available in the U.S. and probably more than 500 globally, the composition and teat conditioning properties can vary widely. Iodine levels in these products vary from 500 ppm (0.05%) to 10,000 ppm (1%), and other formulation options are equally variable. Table 3 lists some of the major formulation variables.
Table 3. Formulation factors influencing teat conditioning – Iodine teat dip
| Iodine Level |
No direct affect |
| Solvent |
Alcohol may tend to dry skin |
| PH |
4.5 to 6.5 skin compatible – lower pH often used to stabilize (old technology) |
| Surfactant |
Type and amount is critical |
| Viscosity |
Effect unknown |
| Drying time |
May be important under wind chill conditions |
| Emollient |
Type and level will have effect |
Iodine level and pH
Iodine levels have not been shown to have a direct affect on teat condition as the other teat dip formulation variables will dominate. Mild teat dips have been formulated with both low and high iodine levels (McKinzie and Hemling, 1996). Teat dip pH is a factor that impacts teat conditioning in iodine teat dips. Historically, many iodine teat dips have been formulated with low pH because of the ease in obtaining stable iodine levels. Current technology allows formulation of iodine teat dips at a more skin friendly pH. Low pH compositions are still common in some countries, such as Australia, and teat condition problems are common. Low pH is known to cause exfoliation of skin (Idson, 1995). The state of California in the US requires that teat dips have a pH of >/= 4. Stable iodine teat dips with pH between 4 and 6.5 are well known. For skin compatibility, pH between 6.5 and about 8.5 should be acceptable also, but for iodine compositions this would result in a decomposition of iodine (I2) to iodide (I-) which is not germicidal.
Iodine is soluble in water only to the extent of 300 ppm at room temperature. Additional solubilizing agents are added to achieve products having higher concentrations. Historically, alcohol has been used in some human health iodine compositions, but this in not common for teat dips. Alcohol is a relatively poor iodine solubilizer, and the larger amounts needed tend to have a drying effect on teat skin. Today most iodine teat dips utilize nonionic surfactants to solubilize iodine. A broad range of non-ionic surfactants may be utilized: nonylphenol ethoxylates, alcohol ethoxylates, alcohol alkylates, sorbitan ester ethoxylates, ethoxylated alkyl-polyglucosides, alkyl ether carboxylates, and ethyleneoxide-propylene oxide copolymers. Many of these are also used as detergents to remove oily soils from hard surfaces. This same property can lead to removal of the natural protective oils in teat skin. The oil-soil detergency differs between the types of non-ionic and teat dips formulated, with the less detergent surfactants being milder to skin. A third alternative for solubilizing iodine is polyvinyl pyrrolidone (PVP). This is a polymeric material that is compatible with teat skin and is widely used in human health skin disinfectants. However, because of its cost, 5-20X that of the non-ionic surfactants it is seldom used as the primary iodine solubilizer in teat dips.
Specific skin conditioning agents are usually added to teat dips to mitigate any adverse affect of the other ingredients or teat dip properties (ie. pH) or to provide a conditioning benefit to address harsh weather or the effects of the milking machine. Skin conditioning agents generally fall into two classifications: moisturizers (humectants) or moisture barriers. Other more exotic agents with claims of wound healing are occasionally used. Moisturizers are additives that attract moisture to the outer layers of the skin to keep it soft and supple. The moisture is pulled from the air or from the deeper layers of skin. Common moisturizers include glycerin, propylene glycol, sorbitol, and aloe. Glycerin (also referred to as glycerol), propylene glycol, glycol ethers and sorbitol are used alone or in combinations in concentrations typically ranging from 2 to 10%. At equal concentrations, glycerin has a 1.35X moisture-binding capacity compared to propylene glycols and a 4X binding capacity compared with sorbitol (Schueller and Romanowski, 1999). Sorbitol, however, shows a higher dynamic hygroscopicity. For iodine teat dips, propylene glycol is often used in concentrated products where glycerin is more difficult to formulate. High glycerin levels may leave a sticky feel on test skin, where sorbitol tends to have a less tacky feel. Aloe or aloe vera is reported to be used in some teat dips or teat dip emollient additives. Aloe vera is one of the 360 species of aloe belonging to the family Liliaceae. Aloe vera gel is extracted from the fleshy leaves and contains 98-99% water. From human health literature, 100% aloe is shown in some studies to have a skin moisturizing or wound healing benefit (Marshall, 1990). The advantage of small amounts of aloe in a teat dip composition is unknown. The solid components of dried aloe vera gel have been shown to react with iodine causing it to be unstable.
A second class of skin conditioners are moisture barriers. These materials function by creating a barrier to prevent evaporation of moisture already present in the skin. The functional properties are determined by measuring the trans-epidermal water loss (TEWL). Typical moisture barriers are lanolin or lanolin derivatives, petrolatum, and mineral oil. Mineral oil and petrolatum are not water soluble and are found in some udder creams but seldom in aqueous teat dips. Lanolin derivatives are more frequently used. Lanolin is derivatized often in the form of an ethoxylated lanolin to make it more water soluble. The lanolin derivatives are used in teat dips only at relatively low concentrations (0.5-1%) because of chemical and physical stability issues. The mosture barrier properties at these low levels is probably minimal (Loden and Maibach, 2000). They may be used in udder creams at higher levels. TEWL measurements have been made on teat skin to evaluate teat conditioning properties of treatments, but with limited success. (Burmeister, et. al, 1998). The lack of success is likely the result of the inability to control all of the environmental factors that the teat is exposed to.
A number of other human health or cosmetic ingredients have been incorporated into teat dips. These include alpha hydroxy acids, allantoin, collagen, vitamins and other ingredients for skin conditioning or wound healing properties. Although data exists to show some effect on human skin, or in pig or rat skin models, little information is available on the benefit in teat dips.
In some countries, teat skin emollient products are sold separately to be added to teat dip solutions on farm. Unless the teat dip and skin conditioning agents are both labeled with specific directions on combining the two products, this practice is discouraged. The mixing of the two products could cause a chemical or physical incompatibility that negates either the germicidal effect of the teat dip, the skin conditioning effect of the emollient, or both.
Viscosity
The viscosity of commercial teat dips varies from essentially water-like (1 centipoise) to the more viscous barrier teat dips (150-500 centipoise). Common post dips that are suited for dipping or spraying have a viscosity for about 5 to 30 centipoise. Increased viscosity will generally result in a thicker layer of product on the teat, especially the teat end. Viscosity alone is not expected to impact teat condition, except under low temperature “wind chill” conditions where increased viscosity may prolong evaporation and cause increased chapping, frost bite or teat end freezing. Under other conditions, the increased thickness of teat dip on the teat skin could be expected to act as a multiplier of the conditioning properties. Harsh products will have more of an adverse effect. Conditioning properties will deliver more benefit.
Pre-dip / udderwash and post dip interactions
Pre-dips have relatively short contact time on teats and the impact on teat condition is expected to be minimal. Dedicated pre-dips are normally formulated with low levels of emollients and usually have germicidal properties that provide rapid kill. Good premilking teat cleaning achieved by pre-dipping may reduce abrasion caused by the rubbing effect of the teat linear on soil on the teat that would overwise be “dry milked”. Questions of possible pre-dip:post-dip interactions have been raised (Farnsworth, 1980), especially for pre-dip:post dip combinations with different germicides, but there is limited published clinical trial data. The minimal contact time for the pre-dip and the small amount of post dip likely to remain on the teat at the next milking would suggest little chance for adverse reaction. Barrier dips may be an exception as the amount of product remaining on the teat at the next milking would be increased. One retrospective survey was conducted that showed some influence of the pre-dip:post dip combination in teat chapping (Buremeister, et al. 1995), but these conclusions were not supported by data from a controlled clinical study (Burmeister, et al. 1998).
TEAT CONDITIONING DATA
Although teat dips have been sold and promoted for teat conditioning benefits for years, scientific studies on the teat conditioning effects of teat dip compositions have only been common during the past 10-15 years. With the efforts to standardize scoring systems and methods, research in this area is expected to expand. We summarize here some of the studies that support some of the discussions presented above. These studies use a 1-5 scoring system for teat skin evaluation that is recommended by Teat Club International. Scoring systems for teat ends either evaluates smoothness-roughness, or incorporates some measure of ring-formation-hyperkeratosis. For both teat skin and teat end, the lower score indicates better condition. In the reported studies, the timing of teat skin evaluation varies depending on the object of the study and what is possible at the trial site and is not consistent between the studies.
Effect of emollient level
Rasmussen (Rasmussen and Hemling, 2002) reported a study of two iodine products with identical, mild surfactant compositions differing in the level of glycerin: 2% versus 8%. The cows in this study were milked with identical VMSTM robotic milkers. The products were evaluated in a double switchback design, including three periods of 4 weeks, with teat skin and teat end evaluations being done prior to milking. The trial showed a significantly better teat skin condition for the product with 8% glycerin (Table 4, and Graph 3). This trial did not show any adverse effect of increasing milking frequency on teat end or teat skin condition.This could be a result of the high emollient, mild surfactant teat dips, or the use of quarter level automatic take-offs on the VMS robot.
Table 4. Teat Conditioning Trial – Influence of teat spraying with an iodine teat dip – 2% or 8% Emollient on teat condition and CMT-score of foremilk
|
Teat Spray |
|
Level of Significance |
|
|
2% Emollient |
8%Emollient |
Treatment
|
Period |
| Teat Skin Score |
2,74
|
2,46 |
*** |
*** |
| Rough Teat Ends, % |
7 |
7 |
NS |
***
|
| Teat End Erosions |
0,89 |
0,87 |
NS |
*** |
| CMT – Score |
1,38 |
1,28
|
** |
0 |
Ø Natural exposure teat conditioning trial
Ø Evaluate teat skin and teat ends
Ø Double switch-back design: three periods of four weeks
Ø Product A = 0.15% iodine, 2% glycerin, Block Copolymer Technology
Ø Product B = 0.15% iodine, 8% glycerin, Block Copolymer technology
Ø Three groups of cows milked on VMS™
Rasmussen, NMC 2002
Graph 3. Teat conditioning Trial- Teat skin - Scored immediately before automatic milking in a switch-back experiment with post teat spray
In a second trial (Rasmussen and Larsen, 1998), Rasmussen evaluated the effects of 10% glycerin (glycerol), a chlorine dioxide teat dip, and a chlorine dioxide teat dip with 10% glycerin. The three products were evaluated in a four week natural exposure trial with teat skin and teat ends evaluated 3 to 4 hours after milking. In this trial, 10% glycerin alone provided the best teat skin and teat end condition. Chlorine dioxide with 10% glycerin provided better teat skin and end condition compared to chlorine dioxide (Table 5). This study shows the benefit of emollients like glycerin and also the emollient germicide combination. This data supports the conclusion that teat conditioning properties are a result of the teat tip composition and not the specific germicide or the emollient.
Table 5. Teat Conditioning Trial – Score of teat skin condition – After four weeks of post milking teat spray
| Teat Spray |
Lactating Cows |
|
|
Teat Middle |
Teat End |
| Glycerol |
2.13a |
2.08a |
| Glycerol & Chlorine Dioxide |
2.38a |
2.21ab |
| Chlorine Dioxide |
3.00b |
2.83c |
| No Teat Spray |
3.00b |
2.71bc |
| STD |
0.400 |
0.38 |
Ø Natural exposure teat conditioning trial
Ø Evaluate teat skin and teat ends, 1(smooth)-6 (rough or damaged) scale Ø Evaluate after four weeksØ a,b,c: numbers with different superscripts are different (p < 0.05)
Rasmussen, Acta vet. scand. 1998, 39, 443-452
Graph 4. Relationship between % teats lesions in 30 herds and glycerol concentration in an iodophor teat dip
Bramley (Bramley, 1980) reports a trial where the glycerin level in an iodine teat dip was varied from 0 to 24%. The impact on the percent of teats affected (chapped?) was reported. He showed continued improvement in teat condition as the glycerin content increased to about 10%. Little additional advantage was seen with increased glycerin content.
Surfactant effect
The impact of surfactant type has been shown by McKinzie (unpublished data) in a natural exposure trial looking at teat skin and teat ends over a six week period. In this trial, two 1% iodine products were tested. Product A contained 10% glycerin and utilized nonylphenol ethoxylates as the iodine complexor. Product B contained 4% glycerin and utilized ethylene oxide-propylene oxide compolymers as the iodine complexor. Both products improved the teat condition score for the first two weeks of the trial, but teat condition for the Product A group deteriorated during weeks 4 to 6. The trial shows the significant effect of the surfactant type in iodine teat dips, which is more important than the difference in glycerin level (Graph 5). This trial is also an interesting example of the change of teat condition over time. From graph 5 one can speculate that some adverse event (weather change, milking system change) occurred around week three that led to a change in teat condition. Product B was better able to maintain good teat condition during this period.
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Graph 5. Natural exposure teat conditioning - Effect of surfactant type
Solvent effects
A six week, split udder, natural exposure trial (Table 6, Graph 6, 7) was run to compare three alcohol containing teat dips with an iodine product (un-published data). The three alcohol products were smooth, or slippery, to the touch and are marketed as being good skin conditioning products. During the six week trial, teat ends improved for three of the products, but deteriorated for the high viscosity alcohol product (C). The other three products showed a similar positive effect on teat ends, with the emollient iodine composition (D) showing a more rapid effect. The low viscosity iodine composition with laurate ester (B) gave the lowest final teat end score. The results suggest some impact of viscosity that could multiply any drying effect of the alcohol, as the high viscosity product would be slower to dry and would leave more product on the teat end. Teat skin condition varied during the six week trial. The teat skin score was consistently lower for the iodine product than the three alcohol products. At week six, the alcohol products (A, B, and C) all had worse teat skin condition than at the start of the trial. The results suggest that the drying effect of the alcohol negated at least some of the beneficial effect of the conditioning agents in compositions A, B and C, even though the alcohol would evaporate within minutes and leave the conditioning agents on the teat.
Table 6. Teat Conditioning Trial - Comparison
|
Germicide |
Emollient |
Viscosity |
Alcohol
|
| A |
Alcohol |
Propylene Glycol |
Low |
25 |
| B |
Alcohol & DCBA |
Laurate Ester |
Low |
35 |
| C |
Alcohol & DCBA |
Laurate Ester |
High |
50 |
| D |
Iodine |
8% Glycerin |
Low |
0 |
|
Graph 6. Change in Teat skin - Alcohol ontaining teat dips A,B,C and a non- alcohol dip D |
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Graph 7. Change in Teat End - Alcohol containing taet dips A,B,C and non-alcohol dip D |
Teat healing
Products and materials have been investigated for the effect of healing of severely chapped or damaged teats. Pig or rat skin models have been used for experimental evaluation, but correlation to teat skin has not been established. The impact of the twice daily milking would also not be evaluated as a factor in these models. Fox (Fox, 1991) developed a live cow model where teats are artificially chapped with solutions of sodium hydroxide. The chapped teats are milked and treated post milking with various teat dips or udder creams. Teat condition was scored daily as the teats healed. In one trial, a 1% iodine/10% glycerin teat dip was found to heal teats faster than an aqueous solution of 10% glycerin (Graph 8) and faster than no dip. In a second artificial chapping trial, Fox showed that a chlorhexidine ointment did not heal teats faster than a 1% iodine/10% glycerin post dip, and was less effective in reducing skin colonization by Staph. aureus (Fox,1992).
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Graph 8. Impact of teat dip and emolient on teat healing
Graph 9. Impact of post dip composition on teat healing |
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Graph 10. Impact of post dip composition on teat healing
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Summary
Maintenance of teat skin condition is important for improved udder health, improved milk yield and reduced milk-out time. Teat dip properties can have a significant effect on teat skin and teat end condition. Clinical trials have shown the impact of teat dip formulation variables on teat skin condition. The teat conditioning properties are the result of the teat dip formulation and not the specific germicide. However, because of their specific chemical characteristics, certain germicides may not allow the same formulation freedom as other germicides. Teat condition can vary with change of environmental conditions and teat tips should be selected that are appropriate for the season. Teat dip compositions containing both germicide and emollient have been shown to be more beneficial than emollient alone in healing chapped teats.
References:
Bramley, A.J. 1980 et al. Mastitis Control and Herd Management, Technical Bulletin 4, National Institute for Research in Dairying, Reading, England, p 60-66.
Buremeister, J.E. et al. 1995. Survey of Dairy Managers in the Pacific Northwest Identifying Factors Asociated with Teat Chapping. Journal of Dairy Science. 78:2073-2082.
Burmeister, J.E. et al. 1998. Effects of Premilking and Postmilking Teat Disinfectants on Teat Skin Condition. Journal of Dairy Science. 81:1910-1916.
Burmeister, J.E., et al. 1998. A Comparison of Two Methods of Evaluation of Teat Skin Pathology, Journal of Dairy Science. 81:1904-1909.
Farnsworth, R.J. 1980. Role of Teat Dips in Mastitis Control. JAVMA. 176:1116-18.
Fox, L.K., et al. 1991. Am J Vet Res. June: Vol. 52. 6:799-802.
Fox, L.K. 1992. J. Dairy Sci. 75:66-71.
Idson, B. May 1995. Retinoids and AHAs, DCI. 25-28.
Loden, M. and H.I. Maibach. 2000. Dry Skin and Moisturizers; Chemistry and Function. CRC Press, Boca Raton. 259-267.
Marshall, J. 1990. Aloe Vera Gel: What is the Evidence? Pharmaceutical Journal. 224:360-362.
McKinzie, M. and T. C. Hemling. 1995. NMC 34th Annual Meeting Proceedings. The Effect of Teat Skin Condition on Milk Yield and Milkout Time. 160-162.
McKinzie, M. and T.C. Hemling. 1996. NMC 35th Annual Meeting Proceedings. Evaluation of a New Barrier Teat Dip Containing 1% Titratable Iodine. 166-167.
Rasmussen, M.D. and H.D. Larsen. 1998. Acta Vet Scand. 39:443-452.
Rasmussen, M.D. and T.C. Hemling. 2002. NMC 41st Annual Meeting Proceedings. 166-167.
Schueller, R. and P. Romanowski. 1999. Conditioning Agents in Skin. Marcel Dekker, Inc., New York. 104p.
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