Studies of Defence Mechanisms and Inflammatory Reactions in the Bovine Teat using a New Experimental Method

Bovine intramammary infections are usually caused by microorganisms entering through the teat canal. The teat canal normally acts as a mechanical and physiological barrier preventing bacteria from entering the teat cistern. This barrier can be broken, e.g. if the teat end is damaged, making it possible for bacteria to invade the teat cistern. If an infection is established inflammatory reac-tions will occur in the udder.     

Effects of amount of milk, milk flow and access to a rubber teat on cross-sucking and non-nutritive sucking in dairy calves

The aim of this study was to test the effects of different amounts of milk, flow rate of milk, and access to a teat after milk intake on non-nutritive sucking on an empty teat and on cross-sucking on other calves in Bos taurus dairy calves. An additional aim was to test if calves prefer to perform non-nutritive sucking on a teat with the taste of milk or on a clean teat. First experiment involved 11 groups of three calves during gradual decrease from 5 to 2.5 and 1 to 0l of whole milk per meal twice daily. Milk flow was either 0.5 or 1l/min, and the teat buckets were either left or removed after milk intake. When the calves were fed with 5l of milk, non-nutritive sucking and cross-sucking decreased (P<0.001), compared to 1 and 2.5l. Removing the empty teat after milk intake increased cross-sucking (P<0.001). Slow milk flow reduced non-nutritive sucking after milk intake (P<0.05), but did not influence cross-sucking. Duration of recorded milk intake was similar with fast flow and 5l of milk, compared to slow flow and 2.5l of milk. The latter combination increased non-nutritive sucking and cross-sucking, suggesting that amount of milk is more important than duration of milk intake.Second experiment was carried out on 12 individually kept calves. The calves received 2.5l of milk either in an open bucket, in a rubber teat bucket, or half/half in both buckets. When not used for feeding, the open bucket and the teat bucket were filled and emptied again to make them 'tasty' with some drops of milk. The tasty teat bucket was either removed or present after milk intake. The calves had always access to a second clean teat bucket. Source of milk had no influence on recorded behaviour after milk intake. The tasty teat was sucked for twice as long as the clean one when both teats were present (P<0.001). When the tasty teat was removed, the calves increased sucking on the clean teat (P<0.001), but decreased total time spent sucking (P<0.001). We conclude that a high amount of milk and the presence of the teat bucket after milk intake reduces cross-sucking, and that a clean teat is less effective in encouraging calves to suck than a teat with taste of milk.     

The Effect of Post Milking Teat Dip and Suckling on Teat Skin Condition,Bacterial Colonisation,and Udder Health

The teat skin of cows was scored (1: smooth as silk; 2: smooth; 3: slightly rough; 4: rough; 5: cracked; and 6: sores) by trained technicians who moved their fingers down the barrel of the teat with a light touch. Technicians ranked the same population of teats in the same rank order, but their mean values differed by half a score which probably could be related to the skin condition of their own fingers. Half udder experiments were carried out for 6 months at 4 farms with 35 to 52 cows each. A postmilking teat spray with 10% glycerol improved teat skin condition (p<0.10) compared with no teat spray. A postmilking teat spray with 120 ppm chlorine dioxide did not influence teat skin condition compared with no teat spray. No differences in udder health could be proven between treatments. Control studies revealed that 10% glycerol as an emollient of a postmilking teat spray improved teat skin condition within 3 weeks from being slightly rough to being smooth for lactating cows (p<0.05) but not for dry cows having smooth teat skin. Neither glycerol nor chlorine dioxide influenced absolute number of bacteria on teat skin after a challenge with Streptococcus uberis and Staphylococcus aureus but half life of S. aureus on unsprayed teats was longest (p = 0.05). Suckling made teat skin more rough than machine milking. Nevertheless, suckling lowered the number of esculin positive bacteria on the teat skin. We concluded that the condition of healthy teat skin (scores 1–4) has no influence on bacterial colonisation in the absence of cracks and sores (scores 5–6).     

Infrared Thermography and Ultrasonography to Indirectly Monitor the Influence of Liner Type and Overmilking on Teat Tissue Recovery

Eight Danish Holstein cows were milked with a 1-mm thick specially designed soft liner on their right rear teat and a standard liner mounted under extra high tension on their left rear teat. Four of the animals were overmilked for 5 min. Rear teats were subjected to ultrasound examination on the first day and to infrared thermography on the second day. Teats were submersed in ethanol 20 min post-milking on the second day. Ultrasonography measurements showed that teat canal length increased by 30–41% during milking. Twenty minutes after milking, teats milked with modified standard liners still had elongated teat canals while teats milked with the soft liner were normalized. Overmilking tended to increase teat wall thickness. Approximately 80% of variability in teat canal length, from before teat preparation to after milking, could be explained by changes during teat preparation. Thermography indicated a general drop in teat temperature during teat preparation. Teat temperature increased during milking and continued to increase until the ethanol challenge induced a significant drop. Temperatures approached pre-challenge rather than pre-milking temperatures within 10 minutes after challenge. Teat temperatures were dependent on type of liner. Mid-teat temperatures post-challenge relative to pre-teat preparation were dependent on overmilking. Thermography and ultrasound were considered useful methods to indirectly and non invasively evaluate teat tissue integrity.     

Dynamics of human milk extraction: A comparative study of breast feeding and breast pumping

We describe a mathematical model of the flow and deformation in a human teat. Our aim is to compare the theoretical milk yield during infant breast feeding with that obtained through the use of a breast pump. Infants use a peristaltic motion of the tongue, along with some suction, to extract milk, whereas breast pumps use a cyclic pattern of suction only. Our model is based on quasi-linear poroelasticity whereby the teat is modelled as a cylindrical porous elastic material saturated with fluid. We impose a cyclic axial suction pressure difference across the teat and impose a radial compressive force moving along the teat which mimics infant suckling. This is compared to the case of cyclic and steady pumping only which models the action of breast pumps. The results illustrate that there is an optimal time to apply the compressive force during the suction cycle that will increase the flow rate in our theoretical teat. The model and results may be of use in the future design of effective breast pumps.     

A study of the development of the teat order in piglets

The sucking and fighting behaviour of three litters of piglets was observed from birth to 4 h of age. Although each piglet sucked from an average of seven teats during this early period, each piglet spent an average of 55% of its sucking time at a single teat. The development of the teat order was studied further by observing the sucking behaviour of 22 litters from 1 to 21 days of age. The development of a stable teat order was progressive and by the end of the second week of lactation the teat orders of the majority of the litters had reached their most stable levels. However, in large litters and litters with low growth rates teat orders were unstable.     

Description and validation of a novel technique to study the bacterial flora of the teat duct of ewes

We describe a new technique that may be used for studying the bacterial flora of the teat duct in live ewes, and we present evidence regarding its accuracy, safety and repeatability. A sterile, plastic, 20 G catheter is used for sampling. The catheter stylet is taken out and the plastic catheter cut with a sterile blade to a length of 2 mm. In order to ensure accurate and consistent cutting of the catheter at the desired length, a sterilized ruler is placed beside the catheter. The whole procedure is carried out under aseptic conditions, on sterilized surgical screens. Before sampling, a thorough disinfection with povidone iodine scrub solution of the teat apex and the lower (1 cm) part of the teat skin is carried out. The catheter is held by the investigator from the cannula hub; then, it is inserted into the teat, rolled around the internal teat wall, in order to sample the mucosa and then withdrawn. Material collected on the tip of the catheter is plated onto bacteriological media. The sensitivity of the technique compared to a method that detects the bacterial flora of the teat after slaughter of the animals (scratching of the teat mucosa by means of a scalpel blade) was 99.1% for field samples and 100% for experimental samples; specificity of the technique was 90.7 and 100%, respectively, kappa coefficient between results of the two methods was 0.9045. The safety of the technique was assessed in an investigation, where ewes were repeatedly (eight times) sampled by means of this technique, throughout their lactation; in no case was clinical or subclinical mastitis recorded. Finally, the repeatability of the method was assessed in 37 paired samples, obtained 30–40 min apart; a 100% match was recorded between bacteriological results of the two samplings of each pair. We conclude that the method can be useful in research studies, in order to obtain information regarding bacterial ecology and dynamics inside the teat of ewes.     

The Interaction of Glycerol and an lodophor Teat Dip

In vivo tests confirmed that significantly more Staphylococcus aureus can be recovered by swabbing from bovine teats dipped in an iodophor glycerol mixture than from teats dipped in an iodophor alone. In contrast no reduction in activity was detected when these materials were compared in a suspension test nor when they were used to treat excised pieces of teat skin. The recovery of Staph. aureus from teat skin by swabbing was shown to be greater in the presence of glycerol alone. It is concluded, therefore, that the addition of glycerol to an iodophor does not reduce bactericidal activity but its presence on teat skin increases the recovery of bacteria surviving disinfectant treatment. The significance of these results for the testing of teat disinfectants is discussed.     

Effectiveness of selected premilking teat-cleaning regimes in reducing teat microbial load on commercial dairy farms

Aims: To determine the effectiveness of premilking teat‐cleaning regimes in reducing the teat microbial load and effect on milk quality. Methods and Results: The effectiveness of several premilking teat‐cleaning regimes in reducing teat microbial load was assessed using 40 cows on each of the four commercial UK dairy farms with herringbone parlours during two sampling periods. In the first experiment, all the treatments reduced teat total viable count (TVC), but there was no significant difference between the hypochlorite wash and dry wipe, iodine dip and dry and alcohol‐medicated wipe or dry wipe alone. In the second experiment, the chlorine wash and dry wipe was significantly more effective in reducing teat TVC than a water wash and dry, chlorine dip and dry or a dry wipe. There was no relationship between cleaning regime and milk TVC, Enterobacteriaceae or Escherichia coli levels. Conclusions: All of the cleaning techniques studied reduced teat microbial load, however, the chlorine wash and dry was the most effective. Significance and Impact of the study: The premilking teat‐cleaning techniques studied reduced the teat microbial load and therefore reduced the potential for milk contamination; however, a wash including an effective disinfectant followed by a dry wipe was the most effective.     

Effects of housing and management conditions on teat cleanliness of dairy cows in cubicle systems taking into account body dimensions of the cows

Dirty udders and teats result in a higher workload in terms of cleaning before milking and may constitute a risk for udder health. The aim of this prevalence study on 23 farms with very low within-farm variation in cubicle measures and other cubicle characteristics was to identify potentially influencing housing and management factors concerning teat and teat tip soiling. Information about udder soiling, housing and management was collected through direct recording and farmers’ interviews. Height at withers, shoulder width and diagonal body length were measured in 79% to 100% of the cows in each herd. On the basis of the 25% largest animals, compliance with recommendations for cubicle measures was calculated, which was generally rather low. Stepwise regression was used to find predictors for the percentage of dirty teats and of dirty teat tips. The final model on dirty teats explained 58.5% of the variance and contained four factors (F = 6.34, P = 0.0023). Less soiled teats were found on farms that conducted teat dipping after milking (t = −3.21, P = 0.0048), had increased daily cubicle maintenance time (t = −2.58, P = 0.0187), deep-bedded cubicles (t = −2.42, P = 0.0265) and decreasing compliance concerning cubicle length (t = 2.33, P = 0.0317). The final model on teat tip soiling explained 46.0% of the variance and contained three factors (F = 5.39, P = 0.0075). Less soiled teat tips were associated with increasing height of bedding material (t = −2.89, P = 0.0094) and decreasing compliance concerning resting length (t = 2.12, P = 0.0470). Difficult to explain was the association found between increased passage soiling and decreased teat tip dirtiness (t = −1.86, P = 0.0790). Thus, even under relatively restrictive cubicle conditions, a certain increase in teat and teat tip soiling was found with increasing cubicle length. However, at the same time, measures relating to good management may positively affect teat and teat tip cleanliness. In addition, deep-bedded cubicles yielded advantages in this regard. Both regression models for teat and teat tip cleanliness contained similar but not identical predictive variables. This indicates that dirtiness of each particular area may originate from slightly different though related causes. The low correlations found between udder, teat and teat tip cleanliness should be considered in future studies.     

The pore of the leaf cavity of Azolla species: teat cell differentiation and cell wall projections

The differentiation of the specialized secretory teat cells of the leaf cavity pore of Azolla species was investigated at the ultrastructural level with emphasis on their peculiar cell wall projections. The results indicated that the projections are formed as soon as the teat cells complete their differentiation and that their production is principally associated with changes in endoplasmic reticulum profiles. The number of projections increases with the teat cell age and is stimulated under salt and P deficiency stresses. Salt stress also promotes their emergence on Azolla species that under normal conditions do not produce projections. Cytochemical tests on different Azolla species showed that the projection composition is almost identical: proteins, acidic polysaccharides, and pectin are always detected. This study revealed that Azolla teat cell projections differ fundamentally from other types of hitherto described cell wall projections that are considered as remnant structures from cell separation. In contrast, in Azolla teat cells projections are actively produced and compounds are excreted by an exocytotic mechanism. The possible role of the projections in the symbiosis of Azolla spp. with Anabaena azollae is discussed.     

Genome‐wide association QTL mapping for teat number in a purebred population of Duroc pigs

Because of increasing litter size in Western pig breeds, additional teats are desirable to increase the capacity for nursing offspring. We applied genome‐wide SNP markers to detect QTL regions that affect teat number in a Duroc population. We phenotyped 1024 animals for total teat number. A total of 36 588 SNPs on autosomes were used in the analysis. The estimated heritability for teat number was 0.34 ± 0.05 on the basis of a genomic relationship matrix constructed from all SNP markers. Using a BayesC method, we identified a total of 18 QTL regions that affected teat number in Duroc pigs; 9 of the 18 regions were newly detected.     

Histological and histochemical studies of the mammary gland innervation in cattle (Bost taurus L.)]

With histological and histochemical methods the innervation of the mammary gland of the cow was studies. The skin of the udder has a weak innervation in contrast to the test. In the district of the basement of the gland body nerve stems enter in the teat. In the skin of the teat only isolated free nerve terminals are found. Intraepithelial nerve terminals are missed. In the middle layer of the teat round the blood vessels bundles of nerve fibers and many organs of nerve terminals were shown. The organs of nerve terminals are typical of the teat and present mechanical receptors. It is discussed the functional significance of the afferent and efferent innervation of the mammary gland of the cow.     

Cow teat skin, a potential source of diverse microbial populations for cheese production

The diversity of the microbial community on cow teat skin was evaluated using a culture-dependent method based on the use of different dairy-specific media, followed by the identification of isolates by 16S rRNA gene sequencing. This was combined with a direct molecular approach by cloning and 16S rRNA gene sequencing. This study highlighted the large diversity of the bacterial community that may be found on teat skin, where 79.8% of clones corresponded to various unidentified species as well as 66 identified species, mainly belonging to those commonly found in raw milk (Enterococcus, Pediococcus, Enterobacter, Pantoea, Aerococcus, and Staphylococcus). Several of them, such as nonstarter lactic acid bacteria (NSLAB), Staphylococcus, and Actinobacteria, may contribute to the development of the sensory characteristics of cheese during ripening. Therefore, teat skin could be an interesting source or vector of biodiversity for milk. Variations of microbial counts and diversity between the farms studied have been observed. Moreover, Staphylococcus auricularis, Staphylococcus devriesei, Staphylococcus arlettae, Streptococcus bovis, Streptococcus equinus, Clavibacter michiganensis, Coprococcus catus, or Arthrobacter gandavensis commensal bacteria of teat skin and teat canal, as well as human skin, are not common in milk, suggesting that there is a breakdown of microbial flow from animal to milk. It would then be interesting to thoroughly study this microbial flow from teat to milk.     

An observational study investigating the association of ultrasonographically assessed machine milking-induced changes in teat condition and teat-end shape in dairy cows

Mechanical forces during machine milking induce changes in teat condition which can be differentiated into short-term and long-term changes. Machine milking-induced short-term changes in teat condition (STC) are defined as tissue responses to a single milking and have been associated with the risk of new intramammary infection. Albeit, their association with teat characteristics, such as teat-end shape, has not been investigated by rigorous methods. The primary objective was to determine the association of STC, as measured by ultrasonography, with teat-end shape. The second objective was to describe possible differences in the recovery time of teat tissue after machine milking among teats with different teat-end shapes. Holstein cows (n=128) were enrolled in an observational study, housed in free-stall pens with sand bedding and milked three times a day. Ultrasonography of the left front and right hind teat was performed after teat preparation before milking (t−1), immediately after milking (t₀) and 1, 3, 5 and 7 h after milking (t₁, t₃, t₅, t₇). The teat tissue parameters measured from ultrasound scans were teat canal length, teat-end diameter, teat-end diameter at the midpoint between the distal and proximal end of the teat canal, teat wall thickness, and teat cistern width. Teat-end shape was assessed visually and classified into three categories: pointed, flat and round. Multivariable linear regression analyses showed differences in the relative change of teat tissue parameters (compared with t−1) at t₀ among teats with different teat-end shapes, with most parameters showing the largest change for round teats. The premilking values were reached (recovery time) after 7 h in teats with a pointed teat-end shape, whereas recovery time was greater than 7 h in teats with flat and round teat-end shapes. Under the same liner and milking machine conditions, teats with a round teat-end shape had the most severe short-term changes. The results of this observational study indicated that teat-end shape may be one of the factors that contribute to the severity of STC.     

Phylogeography and environmental correlates of a cap on reproduction: teat number in a small marsupial, Antechinus agilis

Natural selection should optimize litter size in response to the distribution and abundance of resources during breeding. In semelparous, litter-bearing antechinuses, teat number limits litter size. Consequently adaptation has been inferred in explaining intraspecific, geographic variability in teat number for several Antechinus spp. The phylogeography of teat number variation and associated genetic divergence were assessed in A. agilis using nine microsatellites and mitochondrial cytochrome b sequence data. Six-teat Otway Range animals were divergent in microsatellite allele identity and frequencies: samples from three Otway six-teat sites demonstrated significantly greater similarity genetically to those from six-teat animals approximately 250 km to the west, than to nearby Otway 10-teat samples, or to the six-teat animals at Wilsons Promontory. Gene flow between Otway phenotypes appears to have been limited for sufficient time to enable different microsatellite alleles to evolve. Nonetheless, nuclear genetic evidence suggested only incomplete reproductive isolation, and mitochondrial DNA (mtDNA) haplotypes showed no association with teat number. Other populations across the range were no more genetically differentiated from one another than expected from geographic separation. Principal components and distance-based redundancy analyses found an association between environmental variables and geographic distribution of A. agilis teat number - six-teat animals inhabit more temperate forests, whilst those with more teats experience greater seasonality. The apparent restricted breeding between phenotypically distinct animals, together with phylogenetically separate groups of six-teat animals in different locations with similar environments, are consistent with the hypothesis that adaptation to different habitats drives teat number variation in A. agilis.     

Presence of sub-epithelial lymphoid tissues in the teat of ewe-lambs and adult ewes

In the first part of the study, 24 clinically healthy teats from non-lactating ewe-lambs were examined bacteriologically and histologically. No bacteria were isolated from any of these teats; lymphocytes were observed in teat cisterns of six teats (25%) from three ewes. In the second part, 87 teats from adult ewes were examined; their origin was from lactating mammary glands with no bacteria isolated (n = 23), from glands after lactation with no bacteria isolated (n = 25), from lactating glands with bacteria isolated (n = 22) or from glands after lactation with bacteria isolated (n = 17). The salient histological feature was sub-epithelial leucocytic infiltration. In teat cisterns, lymphocytes were the predominant cell type and in teat ducts, lymphocytes and neutrophils were seen in equal proportions. Sub-epithelial lymphoid nodules, some with germinal centers, were detected in 43 (49%) teats; their majority was observed at the border between teat duct and teat cistern. Presence of bacteria was significantly associated with presence of leucocytic activity (P < 0.001) and with presence of lymphoid nodules (P = 0.032). We conclude that the presence of induced sub-epithelial lymphoid tissue at the border between teat duct and teat cistern appears to be important in protecting the mammary gland during the early stages of bacterial invasion.     

Effects of teat number on litter size in gilts

This study was carried out to investigate the effects of teat number and interval at first estrus and mating on litter size in Duroc, Landrace and Yorkshire gilts. Gilt body weight at first estrus was from 101.5 kg to 115.3 kg and gilts normally attained puberty at 170.5-181.5 days of age. Breed differences among Duroc, Landrace and Yorkshire in body weight and age at first estrus and mating were found. Total teat number of Duroc, Landrace and Yorkshire were 12.5, 14.9 and 13.7, respectively. Teat interval from pectoral to inguinal region and from left to right at first estrus and mating did not show any differences among the breeds. In conclusion, 14 or more teat number compared to 11-13 teat number in gilts increased litter size at birth and at 21 day weaning.     

Genotyping by sequencing reveals a new locus for pig teat number

Teat number is an extremely valuable trait for sow reproduction performance and piglet survival. Here, we used genotyping‐by‐sequencing and a general liner model to carry out genome‐wide analysis of sow total teat number in an Erhualian population. The results indicated that eight SNPs on chromosomes 4, 5, 9 and 10 were significant genome wide (Bonferroni method, P < 2.85E‐7) for sow total teat number. Validation analyses were performed in 298 Erhualian and 904 Large White sows using these significant SNPs and the general liner model procedure in sas . Finally, only the SNP on chromosome 5 was found to be significantly associated with sow teat number in both populations. The GG genotype individuals had 2.23 and 0.82 more teat numbers respectively than did the AA genotype individuals in these two populations (P < 0.05). According to the expression and annotation analyses, we inferred the presence of a gene or lincRNA that could affect teat number by regulating other genes and ultimately affecting the mammogenesis of pigs. Further studies using methods such as Cas9 editing and gene silencing analysis are necessary for additional function analysis.     

Heritability of phenotypic udder traits to improve resilience to mastitis in Texel ewes

There are no estimates of the heritability of phenotypic udder traits in suckler sheep, which produce meat lambs, and whether these are associated with resilience to mastitis. Mastitis is a common disease which damages the mammary gland and reduces productivity. The aims of this study were to investigate the feasibility of collecting udder phenotypes, their heritability and their association with mastitis in suckler ewes. Udder and teat conformation, teat lesions, intramammary masses (IMM) and litter size were recorded from 10 Texel flocks in Great Britain between 2012 and 2014; 968 records were collected. Pedigree data were obtained from an online pedigree recording system. Univariate quantitative genetic parameters were estimated using animal and sire models. Linear mixed models were used to analyse continuous traits and generalised linear mixed models were used to analyse binary traits. Continuous traits had higher heritabilities than binary with teat placement and teat length heritability (h²) highest at 0.35 (SD 0.04) and 0.42 (SD 0.04), respectively. Udder width, drop and separation heritabilities were lower and varied with udder volume. The heritabilities of IMM and teat lesions (sire model) were 0.18 (SD 0.12) and 0.17 (SD 0.11), respectively. All heritabilities were sufficiently high to be in a selection programme to increase resilience to mastitis in the population of Texel sheep. Further studies are required to investigate genetic relationships between traits and to determine whether udder traits predict IMM, and the potential benefits from including traits in a selection programme to increase resilience to chronic mastitis.