Teat End Condition Research Articles

Deep-learning classification of teat-end conditions in Holstein cattle

As a means of preventing mastitis, deep learning for classifying teat-end conditions in dairy cows has not yet been optimized. By using 1426 digital images of dairy cow udders, the extent of teat-end hyperkeratosis was assessed using a four-point scale. Several deep-learning networks based on the transfer learning approach have been used to evaluate the conditions of the teat ends displayed in the digital images. The images of the teat ends were partitioned into training (70 %) and validation datasets (15 %); afterwards, the network was evaluated based on the remaining test dataset (15 %). The results demonstrated that eight different ImageNet models consistently achieved high accuracy (80.3–86.6 %). The areas under the receiver operating characteristic curves for the normal, smooth, rough, and very rough classification scores in the test data set ranged from 0.825 to 0.999. Thus, improved accuracy in image-based classification of teat tissue conditions in dairy cattle using deep learning requires more training images. This method could help farmers reduce the risks of intramammary infections, decrease the use of antimicrobials, and better manage costs associated with mastitis detection and treatment.

Survey of Liner Characteristics Used in Japan

Highlights The vacuum during milking causes teat ends to suck into liners by 7 to 10 cm. Liner rubber is classified as hard or soft. Volume changes are greater in round liners than those of other shapes in the pulsation cycle. Non-round liners did not press completely during the closing phase. The liner shape had a greater effect on liner volume change than the material. ABSTRACT. A variety of liner shapes are used in the dairy industry in Japan, and it is not known which is optimal for maintaining teat-end condition, preventing mastitis, ensuring milk quality, and improving dairy cow and milking system performance. Liners can be generally classified into types based on their internal shape: round, round with ribs on the outside of the liner, triangular, clover-shaped, or square. In addition, liners can be characterized based on the position of the air vent. The optimal combination of air vent location and internal shape for the maintenance of good teat end condition has not been clarified. The aim of this study is to survey liners in Japan to determine the characteristics of liners currently in use. The depth to which the teat end is pulled into the liner during milking was investigated. An experimental vacuum device was fabricated to measure the touch-point and closure-point (the vacuum levels at which the opposite sides of the internal liner surface begin to touch, and the level at which the liner bore completely closes, respectively). In addition, the volume change of the pulsation chamber during the pulsator opening and closing phases was also investigated. The internal shape of the liner was molded when the liner was opened and closed, and the cross-sectional area was compared for each liner type. The findings showed that liner hardness could be characterized as being either soft or hard. The change in the borevolume of round liners during a pulsation cycle, i.e., between the pulsation opening phase and the closing phase, was larger than that observed with the other liners. The cross-sectional area of the molded shape tended to be wider for liners of other shapes than for round liners. This study investigated and compared the characteristics of various types of liners and found that the characteristics varied widely. It is not clear what kind of liner shape is best, and further research is needed. Keywords: Liner internal shape, Overpressure, Pulsation, Teat end condition, Teat end position.

Separable Confident Transductive Learning for Dairy Cows Teat-End Condition Classification.

Simple SummaryThe health of dairy cows is important for milk quality and the health of the mammary gland. Traditionally, teat-end health has been assessed manually through visual inspection of teat-end callosity thickness and roughness (i.e., hyperkeratosis), which is a risk-factor for mastitis. Here, we describe a computer-vision approach to replace the time-consuming and expensive manual assessment of teat-end hyperkeratosis. Using separable confident transductive learning, a convolutional neural network is trained with the goal of increasing the feature differences in the images of teat-ends with different classifications of hyperkeratosis. When compared with the traditional approach of transfer learning of a convolution neural network for classifying the extent of hyperkeratosis, the overall accuracy of our model increased from 61.8 to 77.6%. This substantial improvement in accuracy renders the possibility of using image-based machine learning to routinely monitor hyperkeratosis on commercial dairy farm settings.Teat-end health assessments are crucial to maintain milk quality and dairy cow health. One approach to automate teat-end health assessments is by using a convolutional neural network to classify the magnitude of teat-end alterations based on digital images. This approach has been demonstrated as feasible with GoogLeNet but there remains a number of challenges, such as low performance and comparing performance with different ImageNet models. In this paper, we present a separable confident transductive learning (SCTL) model to improve the performance of teat-end image classification. First, we propose a separation loss to ameliorate the inter-class dispersion. Second, we generate high confident pseudo labels to optimize the network. We further employ transductive learning to narrow the gap between training and test datasets with categorical maximum mean discrepancy loss. Experimental results demonstrate that the proposed SCTL model consistently achieves higher accuracy across all seventeen different ImageNet models when compared with retraining of original approaches.

Effect of transition to an automated milking system for a tie-stall barn on milk production and cow condition.

The effect of the transition from a conventional milking (CM) system in a tie-stall barn to an automated milking (AM) system specialized for a tie-stall barn on milk yield, milk composition, teat-end score, body condition score (BCS), and lying time was evaluated. This study was conducted at a commercial dairy farm from -15 to 153 days after the installation of the AM system. Lactating cows milked with the CM system (average 85 heads) were gradually transitioned to the AM system, and finally, 57 heads were milked with the AM system. No obvious effects of the milking system on milk yield, milk components, BCS, and daily lying time were found based on comparisons between CM and AM cows in the same herd under the same situation of twice-daily milking. The linear mixed-effects model for teat-end scores showed higher scores for front than for rear teats, and small but negative estimates for independent variables of the day after AM, indicating worse teat-end condition for front than for rear teats and improvement of the condition with increased time since AM.

Detecting intramammary infection at the end of lactation in dairy cows

To reduce antimicrobial use, infusion of antimicrobials into only infected cows at the end of lactation (selective dry cow therapy) is preferable to infusion of every cow with antimicrobials. Use of selective dry cow antimicrobial therapy requires differentiation of probably infected from uninfected cows to enable treatment allocation. Milk somatic cell count (SCC) has been used to distinguish between cows with and without intramammary infection (IMI). However, SCC may be influenced by milk yield, stage of lactation, breed, and herd-level variables such as prevalence of infection. Cut points for SCC, to distinguish between cows with and without an IMI, may need to differ between cow age groups and breeds, or among herds. This study evaluated associations between SCC and major pathogen IMI in one or more quarters of 2,606 cows from 36 herds in 4 regions of New Zealand. In the last week of lactation, cows selected at random had milk samples collected from each quarter, and the teat-end condition and hygiene of the udder were scored. Herd- and cow-level data including age, breed, milk volume, and SCC at each production were recorded, and bulk tank milk SCC and volume of milk shipped were collated. At cow level, the association between average, maximum, and last cow-composite SCC, and presence of a major pathogen IMI in one or more quarters of cows, was examined using receiver operator curves. Predictive logistic regression models were then developed that included potential effect modifiers such as age, milk yield, and bulk tank milk SCC. The population average prevalence of major pathogen IMI was 7.2% of cows (95% confidence interval = 5.9-8.6), and this varied significantly between herds. The average, maximum, and last cow-composite SCC of lactation were all predictive of presence of a major pathogen IMI and did not differ in their ability to discriminate infected from uninfected cows. However, the optimal cut points for the last SCC, the maximum SCC, and average SCC were 108, 152, and 105 × 1,000 cells/mL, respectively. Inclusion of age, bulk tank SCC, and history of clinical mastitis improved overall model fit. However, inclusion of these variables did not improve the discriminatory power of maximum cow-composite SCC used alone. We conclude that cow-composite SCC on its own resulted in sensitivities and specificities of between 0.76 and 0.86, and 0.71 to 0.80, respectively, for determination of presence of major pattern IMI, and the predictive value was not improved by addition of other predictor variables.

Feasibility of the use of deep learning classification of teat-end condition in Holstein cattle

Infections with pathogenic bacteria entering the mammary gland through the teat canal are the most common cause of mastitis in dairy cows; therefore, sustaining the integrity of the teat canal and its adjacent tissues is critical to resist infection. The ability to monitor teat tissue condition is a key prerequisite for udder health management in dairy cows. However, to date, routine assessment of teat condition is limited to cow-side visual inspection, making the evaluation a time-consuming and expensive process. Here, we demonstrate a digital teat-end condition assessment by way of deep learning. A total of 398 digital images from dairy cows' udders were collected on 2 commercial farms using a digital camera. The degree of teat-end hyperkeratosis was scored using a 4-point scale. A deep learning network from a transfer learning approach (GoogLeNet; Google Inc., Mountain View, CA) was developed to predict the teat-end condition from the digital images. Teat-end images were split into training (70%) and validation (15%) data sets to develop the network, and then evaluated on the remaining test (15%) data set. The areas under the receiver operator characteristic curves on the test data set for classification scores of normal, smooth, rough, and very rough were 0.778 (0.716-0.833), 0.542 (0.459-0.608), 0.863 (0.788-0.906), and 0.920 (0.803-0.986), respectively. We found that image-based teat-end scoring by way of deep learning is possible and, coupled with improvements in image acquisition and processing, this method can be used to assess teat-end condition in a systematic and efficient manner.

Technical note: A digital technique and platform for assessing dairy cow teat-end condition

Because infections with pathogenic bacteria entering the mammary gland through the teat canal are the most common cause of mastitis in dairy cows, sustaining the integrity of the teat canal and its adjacent tissues is critical to resist infection. The ability to monitor teat tissue condition is therefore a key prerequisite for udder health management in dairy cows. However, to date, routine assessment of teat-end condition is limited to cow-side visual inspection, making the evaluation a time-consuming and expensive process. Here, we illustrate and demonstrate a method for assessing teat-end condition of dairy cows through digital images and software. A digital workflow has been designed where images of dairy cow teats are obtained and processed to display individual teats, and the cow and teat images are labeled and displayed through a graphical user interface. The interface then allows an evaluator to assess quarter- and cow-level teat-end condition and store the results for review and future analysis. The digital workflow permits several advantages such as the ability to perform remote teat-end condition assessments, and assess inter- and intrarater variability of teat-end condition scoring. We demonstrate the image-based teat-end condition assessment of 194 dairy cows that also had cow-side teat-end condition assessments by 2 expert evaluators. Weighted Cohen's kappa statistic (κ) was computed to measure the evaluators' concordance of categorical scores of quarter- and cow-level assessments when using cow-side and image-based assessments. Substantial agreement (0.61 ≤ κ ≤ 0.80) was observed between an evaluator's cow-side and image-based assessments at the quarter and cow level. Moderate agreement (0.41 ≤ κ ≤ 0.60) was observed between evaluators when using image-based assessments at the quarter and cow level. Near perfect agreement (κ = 0.89, 95% confidence interval 0.78-1.00) was observed between evaluators when using cow-side assessments at the quarter level, and substantial agreement (κ = 0.66, 95% confidence interval 0.53-0.79) was observed when using cow-side assessments at the cow level. This suggests that image-based teat-end condition classification is possible, and coupled with improvements in image acquisition and image processing, this method can be used to assess teat-end condition in a systematic and convenient manner.

Comparison of an Experimental Pulsation System with Conventional Pulsation

This study examined whether cows milked with a "copulsation" milking machine differed from cows milked with a standard pulsation milking unit in measures of udder health, teat end condition, and milk flow rate. Study design was a one-year trial with a completely randomized block crossover. Background on the "copulsation" method will be provided.

Milking time hygiene interventions on dairy farms reduce spore counts in raw milk

Spore-forming bacteria, such as Paenibacillus spp. and Bacillus spp., can survive HTST pasteurization in spore form and affect the quality of dairy products (e.g., spoilage in fluid milk). With the demand for higher quality finished products that have longer shelf lives and that can be distributed further and to new markets, dairy processors are becoming interested in obtaining low-spore raw milk supplies. One method to reduce spores in the dairy system will require disrupting the transmission of spores from environmental locations, where they are often found at high concentrations (e.g., manure, bedding), into bulk tank raw milk. Previous research has suggested that cow hygiene factors (e.g., udder hygiene, level of spores in milk from individual cows) are important for the transmission of spores into bulk tank raw milk, suggesting that one potential strategy to reduce spores in bulk tank milk should target cow hygiene in the parlor. To that end, we conducted a study on 5 New York dairy farms over a 15-mo period to evaluate the effect of a combination of intervention strategies, applied together, on the levels of aerobic spores in bulk tank raw milk. The combination of interventions included (1) training milking staff to focus on teat-end cleaning during milking preparation, and (2) implementing changes in laundered towel preparation (i.e., use of detergent, chlorine bleach, and drying). Study design involved collecting bulk tank raw milk samples for a week before and a week after initiating the combination of interventions (i.e., training on the importance of teat-end cleaning and towel treatment). Observations on teat-end condition, udder hygiene scores, and number of kickoffs during milking were also collected for 24 h before and after implementation of the interventions. A total of 355 bulk tank raw milk samples were collected with mean mesophilic and thermophilic spore counts of 2.1 and 2.4 cfu/mL, respectively, before interventions were applied, and 1.6 and 1.5 cfu/mL, respectively, after the interventions were applied. These reductions represent decreases of 37 and 40% in bulk tank raw milk mesophilic spores and thermophilic spores, respectively. Importantly, spore reductions were observed during each of the 3 visits once the interventions were applied, and the largest reduction in spores was recorded for the first sampling after training the milking staff. Further, when a higher proportion of very rough teat ends was observed, bulk tank milk thermophilic spore counts were significantly higher. The intervention strategies tested here represent easy-to-execute cleaning strategies (e.g., focusing on teat-end hygiene and towel washing procedures) that can reduce bulk tank raw milk spore levels. Future studies should validate the effect of on-farm interventions for reduced spore raw milk on corresponding processed product quality and will need to verify the effects of these small changes on product shelf life.

Effect of the pulsation type (alternate or simultaneous) on milk yield and health status of the mammary gland of Murciano-Granadina goats

Recent research into how the pulsation type affects goat milking concluded that alternate pulsation (AP) and simultaneous pulsation (SP) similarly affect the milking efficiency (milking duration and milking fractioning) and teat end condition after milking when both pulsations are employed in short-term experiments. However, the use of SP in high pipeline milking machines led to higher vacuum fluctuations, which, in the long term, may entail a potential risk factor for the mammary gland health status. The aim of this work was to study how AP and SP affect the milk yield, mammary gland health status, and milk composition of goats in the long term, during a complete lactation period, in a high pipeline milking machine. With this objective, 100 Murciano-Granadina goats with similar parturition dates (4 ± 1 postpartum weeks) were divided into 2 similar groups (50 goats per group) according their parity, milk yield, mammary gland health status, and milking duration (after a 15-d pre-experimental period). Throughout the experimental period (7 mo), one group was milked using SP and the other group using AP. Every month, samplings were carried out of the variables related to sanitary status of the mammary gland, milk fractioning, milking duration, average and maximum milk flows, milk composition, teat end status, vacuum fluctuations at the short milk tube during milking, and pulsation tests. Results showed that the use of SP in a high pipeline milking machine showed higher vacuum fluctuations without involving any difference in the other variables studied. We concluded that the use of AP in the milking of Murciano-Granadina goats offers little improvement of the milking performance and increases the investment required for installation and maintenance of the milking machines.

The effect of different levels of teat-end hyperkeratosis on mammary infrared thermograph and mastitis in dairy cows

The object of this study was to assay different levels of teat hyperkeratosis and to determine the connections between teat thermographic characteristics, somatic cells count (SCC) and mastitis in dairy cows. A total of 920 teats of 230 Lithuanian Black and White cows were evaluated to assess teat-end conditions and the thermographic characteristics were determined before evening milking. Teats of the animals were grouped into four different classes of hyperkeratosis. Additionally, quarters of udder were divided into three different classes based on the California mastitis test (CMT) and clinical signs: group 1 (healthy), group 2 (subclinical mastitis), and group 3 (clinical mastitis). The 44.3% of the teats were given a score of N (No ring), 41.1% of the teats were scored S (smooth ring), 11.8% of teats were given a score R (rough ring) and 2.9% of teats were given a score VR (very rough skin). The N and S groups had more healthy udder quarters than R and VR groups (P<0.001). Analysis of thermographic images at the teat sinuses showed that group 1 had lower teat temperature (0.93-1.32 0 C) than group 2 and group 3 (P<0.01). There was a significant positive correlation between milk SCC and temperature of the teats evaluated by hyperkeratosis scores N, S, and R. The results of the present study clearly showed that there was a significant connection between different levels of hyperkeratosis and teat temperature in all groups, indicating a greater risk to mastitis.

Impact of the factors of animal production and welfare on robotic milking frequency

Abstract: The objective of this work was to evaluate the impact of production factors on milking frequency and the latter’s effect on animal welfare in robotic milking. The experiment was performed with Holstein Friesian cows housed in free-stall barns. To assess the impact of production factors, body condition score, milk yield, and concentrate intake were determined. To determine the effects of the milking frequency on welfare, the locomotion and teat-end scores and serum cortisol level were evaluated. Three experimental groups were formed according to the daily average milking frequency: 1.0 to 1.9, 2.1 to 2.9, and above 3.0 milkings per day. The decrease in milking frequency during lactation was related to the reduction in concentrate intake and milk yield. The increase in milking frequency was related to the reduction in the milk flow and the increase in milking duration. Milking frequency was affected by concentrate intake, locomotion problems, milk yield, and lactation stage. The cortisol level and teat-end conditions were not affected by milking frequency. Milking frequency impacts milk flow, duration of milking, and milk composition; however, there is no effect on the indicators of animal welfare.

Milk-flow data collected routinely in an automatic milking system: an alternative to milking-time testing in the management of teat-end condition?

BackgroundHaving a poor teat-end condition is associated with increased mastitis risk, hence avoiding milking machine settings that have a negative effect on teat-end condition is important for successful dairy production. Milking-time testing (MTT) can be used in the evaluation of vacuum conditions during milking, but the method is less suited for herds using automatic milking systems (AMS) and relationships with teat end condition is poorly described. This study aimed to increase knowledge on interpretation of MTT in AMS and to assess whether milk-flow data obtained routinely by an AMS can be useful for the management of teat-end health. A cross-sectional study, including 251 teats of 79 Norwegian Red cows milked by AMS was performed in the research herd of the Norwegian University of Life Sciences. The following MTT variables were obtained at teat level: Average vacuum level in the short milk tube during main milking (MTVAC), average vacuum in the mouthpiece chamber during main milking and overmilking, teat compression intensity (COMPR) and overmilking time. Average and peak milk flow rates were obtained at quarter level from the AMS software. Teat-end callosity thickness and roughness was registered, and teat dimensions; length, and width at apex and base, were measured. Interrelationships among variables obtained by MTT, quarter milk flow variables, and teat dimensions were described. Associations between these variables and teat-end callosity thickness and roughness, were investigated.ResultsPrincipal component analysis showed clusters of strongly related variables. There was a strong negative relationship between MTVAC and average milk flow rate. The variables MTVAC, COMPR and average and peak milk flow rate were associated with both thickness and roughness of the callosity ring.ConclusionsQuarter milk flow rate obtained directly from the AMS software was useful in assessing associations between milking machine function and teat-end condition; low average milk flow rates were associated with a higher likelihood of the teat having a thickened or roughened teat-end callosity ring. Since information on milk flow rate is readily available from the herd management system, this information might be used when evaluating causes for impaired teat-end condition in AMS.

The effect of pulsation ratio on teat condition, milk somatic cell count and productivity in dairy cows in automatic milking.

The pulsation ratio of a milking machine affects milk flow and milking time, and has also been reported to influence teat condition and milk somatic cell count (SCC). However, most studies comparing pulsation ratios have been performed on conventional cluster milking (whole-udder level), where effects such as deteriorated teat end condition and increased milk SCC are likely to be caused by over-milking on teats that are emptied faster than the other teats. When the teat cups are detached from each udder quarter separately which can be done in automatic milking systems (AMS), the risk of over-milking, especially in front teats, may be significantly reduced. This study investigated the effects of pulsation ratio on teat end condition, milk SCC, milk yield, milking time and milk flow in an automatic milking system where each udder quarter is milked separately. In total, 356 cows on five commercial farms were included in a split-udder design experiment comparing three pulsation ratios (60:40, 70:30 and 75:25) with the standard pulsation ratio (65:35) during 6 weeks. Pulsation rate was 60 cycles/min and vacuum level 46 kPa. The 70:30 and 75:25 ratios increased peak and average milk flow and the machine-on time was shorter with 75:25, while both peak and average milk flows were lower and machine-on time was longer with the 60:40 ratio. No negative effects on teat condition or milk SCC were observed with any of the pulsation ratios applied during the study. Thus it is possible that increased pulsation ratio can be used to increase milking efficiency in AMS where quarter milking is applied.

Bovine mastitis prevalence and associated risk factors in dairy cows in Nyagatare District, Rwanda.

In response to farmer requests after milk from their herds was rejected by processors due to poor quality, a study was carried out from April to October 2011 to determine the prevalence of subclinical mastitis, associated risk factors and causative micro-organisms. Samples were collected from 195 dairy cows on 23 randomly selected dairy farms delivering milk to Isangano, Kirebe and Nyagatare milk collection centres in Nyagatare District, Rwanda. The Draminsk® Mastitis Detector was used to detect subclinical mastitis in individual cows based on milk electrical conductivity changes. Risk factors for mastitis that were evaluated included teat-end condition, cow dirtiness, breed, parity, age and stage of lactation. Relationships of these factors with mastitis status were determined using Chi-square analysis, and relative importance as causes of mastitis was assessed using logistic regression. Samples from 16 subclinical mastitis positive dairy cows were analysed to identify causative micro-organisms using Dairy Quality Control Inspection analytical kits. Subclinical mastitis prevalence was 52% across the farms. It was higher with increases in, amongst other risk factors, teat-end damage severity, cow dirtiness, and level of pure dairy breed genetics. The risk factors considered accounted for 62% of mastitis prevalence; teat-end condition alone accounted for 30%. Most of the mastitis cases (87.5%) were caused by coliform bacteria. Considering that farmers are upgrading their local Ankole cows to cross-breed dairy cows that are more susceptible to mastitis, results from this study indicate the need to dip the teats of cows in sanitisers, improve cow hygiene, and introduce mastitis prevention and control programmes.

Management factors and cow traits influencing milk somatic cell counts and teat hyperkeratosis during different seasons

The objective of the study was to analyze the effect of season, parity, stage of lactation and milking procedures on teat-end condition, cow cleanliness and milk somatic cell count (SCC) and identify risk factors associated with milk somatic cell counts greater than 100,000 cells/mL. A group of 15 Italian dairy farms were visited three times during different seasons: the cold (3.8 °C), the hot (23.5 °C) and the mild (12.1 °C) seasons. Hygiene of udder, flanks and legs was scored on 2,330 cows based on a 4-point scale system, from very clean (score 1) to very dirty skin (score 4). On the same cows, a total of 9,201 teats were assessed for teat-end condition and assigned to four different classes of hyperkeratosis: No lesion (N), Smooth ring (S), Rough (R) and Very rough skin (VR). The average percentage of teats classified in the worst classes of hyperkeratosis (R and VR) equaled 15.9%. Teat hyperkeratosis, cow cleanliness and milk somatic cell count were significantly affected by the season. Teat condition was significantly better in primiparous than in multiparous cows and deteriorated during lactation. Cows with the lowest values of SCC, better teat conditions and better hygiene scores were found in the farms where more than one milking practice (among forestripping, pre-dipping and post-dipping) were performed. Multivariate logistic analysis confirmed that parity and days of lactation significantly influence the risk of high somatic cell count. Among environmental and management aspects, clean udders and pre-dipping are associated with a reduced likelihood to have individual cows with milk SCC greater than 100,000 cells/mL. Teat hyperkeratosis does not seem to be a risk factor of high SCC. Milk somatic cell count can be lowered by means of simple actions such as improvement of hygiene condition of cow environment and adoption of pre-dipping.

Overmilking causes deterioration in teat-end condition of dairy cows in late lactation

The objective of the study was to determine the effect of varying degrees of overmilking on teat-end hyperkeratosis, milk production variables and indicators of udder health during late lactation. This was examined by assessing the effect of four end-of-milking criteria on 181 spring-calving, mixed-age Holstein-Friesian cows, at an average 217±24d in milk, over a six-week period. The four treatments were: remove cluster once milk flow rate fell to 0·2kg/min plus 5s (Ovr0), plus 120s (Ovr2), plus 300s (Ovr5), and plus 540s (Ovr9). Daily measurements included individual cow milk yield, milking duration, overmilking duration, maximum milk flow rate, milk flow rate at cluster removal and the number of cluster re-attachments. Individual cow bulk milk samples were collected weekly at AM and PM milkings to determine composition (fat, protein and lactose) and somatic cell count (SCC; AM only). Teat-end hyperkeratosis score was assessed at weeks 0, 3, 5 and 6. At week 6 mean teat-end hyperkeratosis score of the Ovr2 treatment was not greater than Ovr0, whilst Ovr5 was greater than Ovr2 and Ovr9 was greater than Ovr5 and Ovr2. Milk production, milking characteristics and SCC were not different between treatments, except milking duration and milk flow rate at cluster removal. However, higher teat-end hyperkeratosis scores may have a longer-term impact on indicators of udder health if teat-end condition reaches severe levels. Results indicate that to minimise changes in teat-end condition overmilking should be limited to 2min, which has implications for milking management in large parlours not fitted with automatic cluster removers.

Effects of increased milking frequency during early lactation on milk yield and udder health of primiparous Holstein heifers1

In dairy cows, increased milking frequency (IMF) during early lactation stimulates an increase in milk yield that partially persists through the remainder of lactation. However, the effects of IMF on lactation performance and udder health of primiparous heifers have not been clearly established. The objective of this study was to determine the effects of IMF during early lactation on milk yield and composition, udder edema, and teat-end condition of primiparous Holstein heifers. Thirteen heifers were assigned at parturition to unilateral frequent milking (twice-daily milking of the left udder half (2X), and 4-times-daily milking of the right udder half (4X)) from d 1 to 21 of lactation. Heifers were milked twice daily at 0130 and 1330 h, with additional milking of the right udder half at 0430 and 1630 h. Half-udder milk yield and composition were recorded on d 1 and 4, weekly through 35 d in milk (DIM), monthly through 210 DIM, and on d 270±1 of lactation. Udder edema and teat-end scores were evaluated on d 1 and 4, weekly through d 35, and on d 60±1 of lactation. A 1-sided paired t test was used to compare milk yield of 4X- to 2X-udder halves. A 2-sided paired t test was used to test for differences in milk composition, udder edema, and teat-end scores. Overall, 4X stimulated an immediate increase in milk yield. Differential milk yield peaked on d 21 of lactation, with 4X udder halves producing 2.8 kg/d more milk than 2X udder halves (P<0.001). After cessation of 4X, the milk yield differential decreased, but 4X udder halves continued to produce 0.8 kg/d more milk than 2X udder halves through d 270 of lactation (P<0.05). Over the entire lactation, milk component yields and 3.5% fat-corrected milk or energy-corrected milk were greater (P<0.05), whereas somatic cell counts in milk were lower, in 4X udder halves (P<0.05). Udder edema and teat-end condition did not differ between 4X and 2X (P>0.19). In conclusion, IMF during early lactation stimulated a persistent increase in milk yield without negatively affecting several indicators of udder health of primiparous dairy heifers.

Manageable risk factors associated with the lactational incidence, elimination, and prevalence of Staphylococcus aureus intramammary infections in dairy cows

Staphylococcus aureus intramammary infections (IMI) are a major cause of mastitis on farms worldwide. Incidence and elimination rates are the key determinants of prevalence of Staph. aureus, and risk factors associated with these rates must be identified, prioritized, and controlled to obtain long-term reduction in prevalence. The objectives of this study were to identify manageable risk factors associated with the lactational incidence, elimination, and prevalence of Staph. aureus IMI. A cohort of 90 Canadian dairy farms was recruited and followed in 2007 and 2008. Quarter milk samples were collected repeatedly from a selection of cows, and bacteriological culture was realized to assess incidence, elimination, and prevalence of Staph. aureus IMI. Practices used on farms were measured using direct observations and a validated questionnaire. A linear regression model was used to explore the relationship between herd IMI prevalence and incidence and elimination rates. Multilevel logistic regression models were used to compute measures of associations between practices used on farms and IMI incidence, elimination, and prevalence. The herd incidence rate was the most important predictor of herd IMI prevalence: a reduction of the incidence rate equivalent to its interquartile range (0.011 new IMI/quarter-month) was associated with a prevalence reduction of 2.2 percentage points; in comparison, an equivalent increase of the elimination rate by its interquartile range (0.36 eliminated IMI/quarter-month) resulted in a prevalence reduction of 0.4 percentage points. Postmilking teat disinfection and blanket dry-cow therapy were already implemented by most herds. Most of the practices associated with Staph. aureus IMI incidence were related to milking procedures. Among these, wearing gloves during milking showed desirable associations with IMI incidence, elimination, and prevalence. Similarly, adequate teat-end condition and use of premilking teat disinfection were associated with lower IMI incidence and prevalence. The initial herd prevalence of Staph. aureus IMI was positively associated with subsequent IMI incidence. This indicates that, in some situations, an initial reduction of the pool of infected quarters could be justified. Some housing practices were associated with IMI incidence, elimination, or prevalence. The effects of these latter practices, however, were often influenced by specific cow characteristics such as parity or days in milk. These results highlight the importance of good milking practices to prevent Staph. aureus IMI acquisition and, therefore, reduce their prevalence.

Relationship between teat-end condition, udder cleanliness and bovine subclinical mastitis

The aims of the present study were to relate intramammary infection (IMI) occurrence and somatic cell count (SCC) with teat-end condition (TEC) and udder cleanliness (UC). Milk samples from 1931 teats were evaluated according to the presence of IMI and SCC. Scores were applied to teats according to the TEC and to UC. Teats ends with a very rough ring had the largest number of IMI when compared to the other three categories, as well as animals with dirtier udders. The change in a TEC score increased by around 30% the chance of IMI. Also, the chance of the animal developing IMI increased by approximately 47% when the UC score increased. No significant association between both scores and quarter SCC was found. It can be concluded that animals with very rough teat end rings and very dirty udders have a greater predisposition to IMI.