Randomized-controlled study assessing the effect of milking permission settings and concentrate supplementation on milking frequency and milk yield in a pasture-based automatic milking system.

This study aimed to verify the effect of milking permission (MPE) and concentrate supplementation (CS) on milking frequency (milkings per cow per day) and milk yield (kilograms per cow per day) in a farm using a pasture-based automatic milking system (AMS). Sixty-eight cows milked using this AMS unit were randomly assigned to 1 of 4 groups homogeneous for parity, DIM, and milk yield. Treatments used were frequent or restricted MPE, that granted cows permission to milk after 6 to 8 h or 9.6 to 14 h of the previous milking, respectively; and low (LC) or high (HC) CS of 0.5 kg or 3.5 kg/cow per day, respectively. The combination of the 2 levels of MPE and the 2 levels of CS resulted in the 4 treatment combinations (frequent HC [FHC], restricted HC [RHC], frequent LC [FLC], and restricted LC [RLC]). This study was designed as a 2 × 2 factorial arrangement with treatment crossover: each of the 4 cow groups was randomly assigned to 1 of the 4 treatment combinations for a 5-wk experimental period (1 pretreatment week and 4 treatment weeks), and after each 5-wk period groups crossed over to another treatment combination until they experienced all. Statistical analysis assessed the effect of MPE, CS, and their interaction on milk yield, milking frequency, box time, milking time, and average milk-flow rate. This was done using a mixed model analysis with repeated measures to account for repeated observations on the experimental unit (cow). Milk yield per cow per day and milkings per cow per day were significantly higher with the frequent compared with the restricted MPE (1.5 kg and 0.65 milkings, respectively). Milk yield per cow per day and milkings per cow per day were significantly higher with the HC compared with the LC CS (3.1 kg and 0.25 milkings, respectively). Additionally, milk yield per cow per day was affected by the interaction of MPE and CS and it was highest with the FHC (20.1 kg) treatment combination, followed by RHC (18.2 kg) treatment combination. The number of milkings per cow per day were also affected by the interaction of MPE and CS. The highest estimated number of milkings per cow per day was recorded for the FHC (2.12) and the FLC (1.77) treatment combinations, followed by the RHC (1.38) and RLC (1.23) treatment combinations. Similarly, milking interval was 2.5 h longer for the RLC treatment combination compared with RHC. The shortest milking interval was observed for the FHC (11 h) and FLC (12.8 h) treatment combinations. In conclusion, the study showed that allowing access to the robot between 6 to 8 h after the previous milking was sufficient (even with a minimal level of CS) to achieve acceptable milk production and milking performance in a pasture-based AMS.

Monitoring residue concentrations in milk from farm and throughout a milk powder manufacturing process.

The experiments reported in this research paper aimed to investigate differences in the levels of chlorate (CHLO), perchlorate (PCHLO), trichloromethane (TCM) and iodine residues in bulk tank (BT) milk produced at different milk production periods, and to monitor those levels throughout a skim milk powder (SMP) production chain (BTs, collection tankers [CTs], whole milk silo [WMS] and skim milk silo [SMS]). Chlorate, PCHLO and iodine were measured in SMP, while TCM was measured in the milk cream. The CHLO, TCM and iodine levels in the mid-lactation milk stored in the WMS were lower than legislative and industrial specifications (0.0100 mg/kg, 0.0015 mg/kg and 150 µg/l, respectively). However, in late-lactation, these levels were numerically higher than the mid-lactation levels and specifications. Trichloromethane accumulated in the cream portion after separation. Perchlorate was not detected in any of the samples. Regarding iodine, the levels in mid-lactation reconstituted SMP were higher than that required by manufacturers (100 µg/l), indicating that the levels in milk should be lower than 142 µg/l. The higher residue levels observed in late-lactation could be related to the low milk volume produced during that period and changes in sanitation practices, while changes in feed management could have affected iodine levels. This study could assist in controlling and setting limits for CHLO, TCM and iodine levels in milk, ensuring premium quality dairy products.

Microbiological quality of milk from farms to milk powder manufacture: an industrial case study.

The experiments reported in this research paper aimed to track the microbiological load of milk throughout a low-heat skim milk powder (SMP) manufacturing process, from farm bulk tanks to final powder, during mid- and late-lactation (spring and winter, respectively). In the milk powder processing plant studied, low-heat SMP was produced using only the milk supplied by the farms involved in this study. Samples of milk were collected from farm bulk tanks (mid-lactation: 67 farms; late-lactation: 150 farms), collection tankers (CTs), whole milk silo (WMS), skim milk silo (SMS), cream silo (CS) and final SMP. During mid-lactation, the raw milk produced on-farm and transported by the CTs had better microbiological quality than the late-lactation raw milk (e.g., total bacterial count (TBC): 3.60 ± 0.55 and 4.37 ± 0.62 log 10 cfu/ml, respectively). After pasteurisation, reductions in TBC, psychrotrophic (PBC) and proteolytic (PROT) bacterial counts were of lower magnitude in late-lactation than in mid-lactation milk, while thermoduric (LPC-laboratory pasteurisation count) and thermophilic (THERM) bacterial counts were not reduced in both periods. The microbiological quality of the SMP produced was better when using mid-lactation than late-lactation milk (e.g., TBC: 2.36 ± 0.09 and 3.55 ± 0.13 cfu/g, respectively), as mid-lactation raw milk had better quality than late-lactation milk. The bacterial counts of some CTs and of the WMS samples were higher than the upper confidence limit predicted using the bacterial counts measured in the farm milk samples, indicating that the transport conditions or cleaning protocols could have influenced the microbiological load. Therefore, during the different production seasons, appropriate cow management and hygiene practices (on-farm and within the factory) are necessary to control the numbers of different bacterial groups in milk, as those can influence the effectiveness of thermal treatments and consequently affect final product quality.

Machine Learning Based Prediction of Insufficient Herbage Allowance with Automated Feeding Behaviour and Activity Data.

Sensor technologies that measure grazing and ruminating behaviour as well as physical activities of individual cows are intended to be included in precision pasture management. One of the advantages of sensor data is they can be analysed to support farmers in many decision-making processes. This article thus considers the performance of a set of RumiWatchSystem recorded variables in the prediction of insufficient herbage allowance for spring calving dairy cows. Several commonly used models in machine learning (ML) were applied to the binary classification problem, i.e., sufficient or insufficient herbage allowance, and the predictive performance was compared based on the classification evaluation metrics. Most of the ML models and generalised linear model (GLM) performed similarly in leave-out-one-animal (LOOA) approach to validation studies. However, cross validation (CV) studies, where a portion of features in the test and training data resulted from the same cows, revealed that support vector machine (SVM), random forest (RF) and extreme gradient boosting (XGBoost) performed relatively better than other candidate models. In general, these ML models attained 88% AUC (area under receiver operating characteristic curve) and around 80% sensitivity, specificity, accuracy, precision and F-score. This study further identified that number of rumination chews per day and grazing bites per minute were the most important predictors and examined the marginal effects of the variables on model prediction towards a decision support system.

The effect of different precooling rates and cold storage on milk microbiological quality and composition.

The objective of this study was to measure the effect of different milk cooling rates, before entering the bulk tank, on the microbiological load and composition of the milk, as well as on energy usage. Three milk precooling treatments were applied before milk entered 3 identical bulk milk tanks: no plate cooler (NP), single-stage plate cooler (SP), and double-stage plate cooler (DP). These precooling treatments cooled the milk to 32.0 ± 1.4°C, 17.0 ± 2.8°C, and 6.0 ± 1.1°C, respectively. Milk was added to the bulk tank twice daily for 72 h, and the tank refrigeration temperature was set at 3°C. The blend temperature within each bulk tank was reduced after each milking event as the volume of milk at 3°C increased simultaneously. The bacterial counts of the milk volumes precooled at different rates did not differ significantly at 0 h of storage or at 24-h intervals thereafter. After 72 h of storage, the total bacterial count of the NP milk was 3.90 ± 0.09 log10 cfu/mL, whereas that of the precooled milk volumes were 3.77 ± 0.09 (SP) and 3.71 ± 0.09 (DP) log10 cfu/mL. The constant storage temperature (3°C) over 72 h helped to reduce bacterial growth rates in milk; consequently, milk composition was not affected and minimal, if any, proteolysis occurred. The DP treatment had the highest energy consumption (17.6 ± 0.5 Wh/L), followed by the NP (16.8 ± 2.7 Wh/L) and SP (10.6 ± 1.3 Wh/L) treatments. This study suggests that bacterial count and composition of milk are minimally affected when milk is stored at 3°C for 72 h, regardless of whether the milk is precooled; however, milk entering the tank should have good initial microbiological quality. Considering the numerical differences between bacterial counts, however, the use of the SP or DP precooling systems is recommended to maintain low levels of bacterial counts and reduce energy consumption.

Estimating the impact of somatic cell count on the value of milk utilising parameters obtained from the published literature.

The impact of mastitis on milk value per litre independent of the effect of mastitis on milk volume, was quantified for Ireland using a meta-analysis and a processing sector model. Changes in raw milk composition, cheese processing and composition associated with increased bulk milk somatic cell count (BMSCC) were incorporated into the model. Processing costs and market values were representative of current industry values. It was assumed that as BMSCC increased (i) milk fat and milk protein increased and milk lactose decreased, (ii) fat and protein recoveries decreased, (iii) cheese protein decreased and cheese moisture increased. Five BMSCC categories were examined from ⩽100 000 to >400 000 cells/ml. The analysis showed that as BMSCC increased the production quantities reduced. An increase in BMSCC from 100 000 to >400 000 cells/ml saw a reduction in net revenue of 3·2% per annum (€51·3 million) which corresponded to a reduction in the value of raw milk of €0·0096 cents/l.

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±24 d in milk, over a six-week period. The four treatments were: remove cluster once milk flow rate fell to 0·2 kg/min plus 5 s (Ovr0), plus 120 s (Ovr2), plus 300 s (Ovr5), and plus 540 s (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 2 min, which has implications for milking management in large parlours not fitted with automatic cluster removers.

Milking efficiency of swingover herringbone parlours in pasture-based dairy systems.

The objective of this study was to collect and analyse milking data from a sample of commercial farms with swingover herringbone parlours to evaluate milking efficiency over a range of parlour sizes (12-32 milking units). Data were collected from 19 farms around the Republic of Ireland equipped with electronic milk metres and herd management software that recorded data at individual milking sessions. The herd management software on each farm was programmed to record similar data for each milking plant type. Variables recorded included cow identification, milking date, identification time, cluster-attachment time, cluster/unit number, milk yield, milking duration, and average milk flow rate. Calculations were performed to identify efficiency benchmarks such as cow throughput (cows milked per h), milk harvesting efficiency (kg of milk harvested per h) and operator efficiency (cows milked per operator per h). Additionally, the work routine was investigated and used to explain differences in the benchmark values. Data were analysed using a linear mixed model that included the fixed effects of season-session (e.g. spring-AM), parlour size and their interaction, and the random effect of farm. Additionally, a mathematical model was developed to illustrate the potential efficiency gains that could be achieved by implementing a maximum milking time (i.e. removing the clusters at a pre-set time regardless of whether the cow had finished milking or not). Cow throughput and milk harvesting efficiency increased with increasing parlour size (12 to 32 units), with throughput ranging from 42 to 129 cows/h and milk harvesting efficiency from 497 to 1430 kg/h (1-2 operators). Greater throughput in larger parlours was associated with a decrease in operator idle time. Operator efficiency was variable across farms and probably dependent on milking routines in use. Both of these require consideration when sizing parlours so high levels of operator efficiency as well as cow throughput can be achieved simultaneously. The mathematical model indicated that application of a maximum milking time within the milking process could improve cow throughput (66% increase in an 18-unit parlour when truncating the milking time of 20% of cows). This could allow current herd milking durations to be maintained as herd size increases.

Strategy for the reduction of Trichloromethane residue levels in farm bulk milk.

High fat dairy products, such as butter and margarine can be contaminated during the milk production process with a residue called Trichloromethane (TCM), which results from the use of chlorine based detergent solutions. Although, TCM concentrations in Irish products are not at levels that are a public health issue, such contamination can cause marketing difficulties in countries to which Irish products are being exported. In an attempt to reduce such milk residues, a template procedure was developed, tried and tested on 43 farms (from 3 processing companies). This involved identifying farms with high TCM milk, applying corrective action in the form of advice and recommendations to reduce TCM and re-measuring milks from these farms. Trichloromethane in milk was measured by head-space gas chromatography with electron capture detector. The TCM reduction strategy proved successful in significantly reducing the levels in milk in the farms tested, e.g. TCM was reduced from 0.006 to the target of 0.002 mg/kg (P < 0.05). The strategy was then applied to farms who supplied milk to six Irish dairy processors with the objective of reducing TCM in those milks to a level of ≤ 0.002 mg/kg. Initially, milk tankers containing milks from approximately 10-15 individual farms were sampled and analysed and tankers with high TCM (>0.002 mg/kg) identified. Individual herd milks contributing to these tankers were subsequently sampled and analysed and farms supplying high TCM identified. Guidance and advice was provided to the high TCM milk suppliers and levels of TCM of these milk supplies were monitored subsequently. A significant reduction (minimum P < 0.05) in milk TCM was observed in 5 of the 6 dairy processor milks, while a numerical reduction in TCM was observed in the remaining processor milk.

The impact of work organisation on the work life of people on pasture-based dairy farms.

The seasonal workload combined with increased dairy herd sizes and a declining workforce have created social sustainability challenges for pasture-based dairy farms. Effective work organisation can build productive capacity that may have a positive impact on this scenario. Our objective was to develop a framework to characterise and examine the effect of work organisation on the working situations of the people involved in a sample of 55 pasture-based dairy farms in Ireland. We conceptualised that effective work organisation on a dairy farm could be considered as a system that is efficient from a labour input perspective, resulting in a profitable farming system with outcomes of good operator well-being, health and safety, and quality of life. A literature review established efficiency & productivity, flexibility and standardisation as our three characteristics of work organisation. Using data from an existing labour time-use study completed from the 1st February to 30th June 2019, we aimed to test the veracity of these work organisation characteristics in the Irish pasture-based dairy system. Two proxy indicators were selected to represent each of the three work organisation characteristics, and each of the 55 farms were categorised into quartiles based on their ranking for these six indicators (1 = most effective quartile to 4 = least effective quartile). The most and least effective quartiles of farms for work organisation showed similar levels of farm labour input and labour efficiency. Farmers in the most effective work organisation quartile were working 51.2 h/week from February to June compared with 70.0 h/week for farmers in the least effective quartile, which was attributed to later start times, earlier finish times, and more time at non-farm activity. Farms achieving effective work organisation had a labour-efficient system with relatively low farmer working hours. Extension of the work organisation concept to other farms could improve their labour situation and aid in alleviating some of the key quality of life challenges faced by dairy farmers.

Longitudinal measures of labour time-use on pasture-based dairy farms, incorporating the impact of specific facilities and technologies.

The seasonal workload on pasture-based dairy farms, combined with increased herd sizes, have led to an increased focus on farm labour time-use and techniques that can reduce farm labour demand. The objective of this study was to measure labour time-use over time on a sample of pasture-based dairy farms and examine the impact that specific facilities and technologies could have on labour demand in real farm situations. Fifty-seven farms completed two labour time-use studies in spring 2019 and 2021 (1st February to 30th April). Farm labour input was recorded on one day each week during the study period. Results showed that farm labour input increased by 3% (1 364 to 1 403 h) between spring 2019 and 2021 and farm labour efficiency improved by 7% (10.7 to 10.0 h/cow), while herd size increased by 10% (145 to 160 cows). Case study farms that made substantial changes to the milking and calf care facilities and practices (between 2019 and 2021) were selected to examine the impact of these changes on labour demand and efficiency. The four case study farms that implemented new milking parlours or added additional milking units improved their milking efficiency by 15% (2.89 to 2.45 h/cow per farm) and reduced milking labour input by 15% (402 to 342 h per farm). Seventeen farms made substantial calf care changes such as constructing a new calf shed, installing an automatic calf feeder, selling male calves and contract rearing heifer calves preweaning. These farms had on average 26 more cows per farm in 2021 than in 2019 (increasing from 137 to 163 cows), but calf care labour input declined by 5% (240 to 228 h per farm) and calf care labour efficiency improved by 16% (1.83 to 1.53 h/cow per farm). Of these farms, the largest improvement was observed on the eight farms that installed automatic calf feeders, where calf care labour efficiency improved by 23% (1.76 to 1.36 h/cow). Results of this study contribute to our understanding of labour use on pasture-based dairy farms and how it can change over time. The real-time on-farm case studies can reassure farmers of the positive benefits that the facilities and technologies outlined in this study can have on labour efficiency.

Chlorate Levels in Dairy Products Produced and Consumed in Ireland.

In recent years, chlorate has become a residue of concern internationally, due to the risk that it poses to thyroid gland function. However, little is known about its occurrence in dairy products of Irish origin. To address this, a study was conducted in which samples of milk (n = 317), cream (n = 199), butter (n = 178), cheese (n = 144) and yoghurt (n = 440) were collected from grocery stores in the Republic of Ireland. Sampling was conducted across spring, summer, autumn and winter of 2021. Samples from multiple manufacturers of each respective dairy product were procured and analysed for chlorate using UPLC-MS/MS. Chlorate was detected in milk, cream, natural, blueberry, strawberry and raspberry yoghurts. Mean chlorate levels detected in these products were 0.0088, 0.0057, 0.055, 0.067, 0.077 and 0.095 mg kg-1, respectively. Chlorate was undetected in butter and cheese (<0.01 mg kg-1). All products sampled, except yoghurt, were found to be compliant with the EU limit for chlorate in milk (0.10 mg kg-1). Some manufacturers produced product with greater incidence and levels of chlorate. Chlorate levels from samples tested at different times of the year did not differ significantly, with the exception of strawberry and raspberry yoghurts which had higher chlorate levels in the winter period.

Milking parlour size, pre-milking routine and stage of lactation affect efficiency of milking in single-operator herringbone parlours.

Efficient milking systems, in terms of labour demand, capital investment and cow udder health are critical to successful dairy herd expansion. The objective of this study was to establish the effect of two primary influencing factors on efficient milking performance, i.e. parlour size (number of milking units) and pre-milking routine (full and nil) of spring-calved cows, in a single-operator side-by-side, swing-over milking parlour. Efficiency parameters investigated in a 5 × 2 factorial design included milk-flow and yield, row time, over-milking duration and operator idle time. Five combinations of parlour size (14, 18, 22, 26 and 30 milking units) each with two different pre-milking routines (Full: spray, strip, wipe, attach clusters, and Nil: attach clusters) were examined with one milking operator. The trial was carried out over 40 milking sessions and cows (up to 120) were randomly assigned to groups (n = 14, 18, 22, 26 or 30) before each milking session. Row within a milking session was the experimental unit. The experiment was carried out at both peak and late lactation. The data were analysed with a mixed model using GenStat 13.2. The full pre-milking routine reduced time to milk let-down and milking time, increased average flow rate but did not affect milk yield. As milking unit number increased, the duration of over-milking (defined as time at milk flow rate < 0·2 kg/min) increased more with a full compared with nil routine. Thus, the use of pre-milking preparation decreased milking time per cow but as parlour size increased, milking row times, as well as the proportion of cows that were over-milked, also increased, thereby reducing overall efficiency. These results have implications for milking management in single-operator swing-over, tandem and rotary parlours with seasonally calved herds.

Proteomic study of proteolysis during ripening of Cheddar cheese made from milk over a lactation cycle.

Milk for cheese production in Ireland is predominantly produced by pasture-fed spring-calving herds. Consequently, there are marked seasonal changes in milk composition, which arise from the interactive lactational, dietary and environmental factors. In this study, Cheddar cheese was manufactured on a laboratory scale from milk taken from a spring calving herd, over a 9-month lactation cycle between early April and early December. Plasmin activity of 6-months-old Cheddar cheese samples generally decreased over ripening time. One-dimensional urea-polyacrylamide gel electrophoresis (PAGE) of cheese samples taken after 6 months of ripening showed an extensive hydrolysis of caseins, with the fastest hydrolysis of α(s1)-caseins in cheeses made in August. A proteomic comparison between cheeses produced from milk taken in April, August and December showed a reduction in levels of ß-casein and appearance of additional products, corresponding to low molecular weight hydrolysis products of the caseins. This study has demonstrated that a seasonal milk supply causes compositional differences in Cheddar cheese, and that proteomic tools are helpful in understanding the impact of those differences.

Effect of Pre-Milking Teat Foam Disinfection on the Prevention of New Mastitis Rates in Early Lactation.

The objective of this study was to determine the benefit of pre-milking teat foam disinfection on the prevention of new infections by contagious and environmental bacteria in two spring calving herds managed outdoors (Herd 1 [H1]; 331 cows and Herd 2 [H2]; 142 cows). Four pre-milking teat preparation treatments were applied post calving; with each herd receiving two treatments; using a split udder design (for approx. 15 weeks). These treatments included; (1) 'water wash, foam application and dry wipe (WFD) in H1'; (2) 'water wash and dry wipe (WD)' in H1; (3) 'foam application and dry wipe (FD)' in H2; (4) 'no teat cleaning preparation (NP)' in H2. Individual quarter foremilk samples were collected on four occasions and all clinical and sub-clinical cases were recorded. The mean SCC of quarter foremilk samples was 134 × 103 cells/mL and 127 × 103 cells/mL for WD and WFD, respectively, and 109 × 103 cells/mL and 89 × 103 cells/mL for NP and FD, respectively (p > 0.05). Lower bacterial counts were observed on teat skin that received a foaming treatment. Pre-milking teat disinfection using a foaming product may be of little benefit, in early lactation, for a pasture-based dairy herd.

The effect of disinfectant ingredients on teat skin bacteria associated with mastitis in Irish dairy herds.

BACKGROUND: Teat disinfection is an important step in the control of mastitis within a dairy herd. The objective of this study was to evaluate the effectiveness of 96 commercially available teat disinfectant products in Ireland against bacterial isolates on teat skin. Teat disinfection products were applied to the teats of seventeen Holstein-Friesian cows. A split-udder model was used where one cow received two different teat disinfection products on each day. A composite swab sample was taken of the left teats and the right teats before and after teat disinfectant application. Swab samples were plated onto 3 different selective agars to enumerate bacterial counts of streptococcal, staphylococcal and coliform isolates. RESULTS: Streptococcal isolates were the most prominent bacterial group recovered on teat swabs taken before the application of a teat disinfection product (55.0%), followed by staphylococcal isolates (41.3%) and coliform isolates (3.7%). Products were reclassified by active ingredients (n = 9) for analysis. These ingredient groups included; chlorhexidine, chlorine dioxide, diamine, iodine, iodine and lactic acid, lactic acid, lactic acid and chlorhexidine, lactic acid and hydrogen peroxide, and lactic acid and salicylic acid. The ingredient group, chlorine dioxide, resulted in comparable reductions to the iodine group for streptococcal isolates. The ingredient group, iodine combined with lactic acid, resulted in the greatest reduction of staphylococcal isolates. When observing products individually, a product containing 1.6% w/w lactic acid combined with hydrogen peroxide was the most effective at reducing streptococcal isolates on the teat skin, whereas a product containing lactic acid combined with 0.6% w/w chlorhexidine was the most effective against staphylococcal isolates. Minor differences were observed regarding the relationship between effectiveness and active ingredient concentration between products. CONCLUSIONS: This study suggests that some teat disinfectant products achieve a higher reduction in bacterial levels against different specific bacterial groups on teat skin than other products. Therefore, when choosing a teat disinfectant product, the bacteria in the dairy herds' environment should be considered. Further studies are necessary to evaluate products efficacy against new IMIs and any possible effects on teat skin condition.

Screening commercial teat disinfectants against bacteria isolated from bovine milk using disk diffusion.

BACKGROUND AND AIM: Teat disinfection is an important tool in reducing the incidence of bovine mastitis. Identifying the potential mastitis-causing bacterial species in milk can be the first step in choosing the correct teat disinfectant product. The objective of this study was to screen commercial teat disinfectants for inhibition against mastitis-associated bacteria isolated from various types of milk samples. MATERIALS AND METHODS: Twelve commercially available teat disinfectant products were tested, against 12 mastitis-associated bacteria strains isolated from bulk tank milk samples and bacterial strains isolated from clinical (n=2) and subclinical (n=3) quarter foremilk samples using the disk diffusion method. RESULTS: There was a significant variation (7-30 mm) in bacterial inhibition between teat disinfection products, with products containing a lactic acid combination (with chlorhexidine or salicylic acid) resulting in the greatest levels of bacterial inhibition against all tested bacteria (p<0.05). CONCLUSION: In this study, combined ingredients in teat disinfection products had greater levels of bacterial inhibition than when the ingredients were used individually. The disk diffusion assay is a suitable screening method to effectively differentiate the bacterial inhibition of different teat disinfectant products.

Effect of restricting silage feeding prepartum on time of calving, dystocia and stillbirth in Holstein-Friesian cows.

A study was carried out to investigate the effect of restricting silage feeding on time of calving and calving performance in Holstein-Friesian cows. In the treatment group (n = 1,248 cows, 12 herds) silage feeding commenced in the evening (17:00 to 20:00 h), after a period of restricted access (2 to 10 h) while in the control group ad-libitum access to silage was provided over the 24 h period (n = 1,193 cows, 12 herds). Daytime and nighttime calvings were defined as calvings occurring between the hours of 06:30 and 00:29 and between 00:30 and 06:29, respectively. Restricting access to silage resulted in less calvings at night compared to cows with ad-libitum access to silage (18 vs 22%, P < 0.05). Cows with restricted access to silage had a higher percentage of difficult calvings (11 vs 7%, P < 0.001) and stillbirths (7 vs 5%, P < 0.05) compared to cows in the control group. The percentage of calvings at night was lower (13%) when access to silage was restricted for 10 h compared to 2, 4 or 6 h (22, 18, 25%, respectively) (P < 0.001). Calf sire breed, calf gender or cow parity did not influence time of calving. In conclusion, offering silage to pregnant Holstein-Friesian cows in the evening, after a period of restricted access, reduced the incidence of nighttime calvings, but increased the incidence of dystocia and stillbirth.

Investigation of the persistence of closantel residues in bovine milk following lactating-cow and dry-cow treatments and its migration into dairy products.

Closantel is a veterinary drug used to treat liver fluke in cattle and sheep. A provisional maximum residue limit (MRL) of 45 µg/kg in milk has been set by the European Union. The purpose of this study was to investigate the persistence of closantel residues in milk and the migration of residues into milk products. Following dry-cow treatment, residues ranged from undetectable to 8.7 µg/kg at the first milking. Following lactating-cow treatment, residues detected ranged from 278 to 482 µg/kg at day 1 post-treatment and were detectable above the MRL for 52 days and detectable for 198 days. At day 2 and day 23 post-treatment, the milk was collected and dairy products manufactured. Closantel residues concentrated in the cheese, butter, and skim milk powder. The results indicate that closantel is best used as a dry-cow treatment.

Effect of milk feed source, frequency of feeding and age at turnout on calf performance, live-weight at mating and 1st lactation milk production.

Female calves (n = 108) were assigned to 6 cold milk feeding treatments in two experiments for a 70-day period. Live-weight (LW) was measured weekly, with an additional LW taken at day 410 and post-calving for animals in experiment 1. In Experiment 1, the effect of feeding frequency and age of turnout to pasture on calf performance and 1st lactation milk yields were evaluated. The whole milk (WM) feeding treatments applied were (i) once daily feeding (OD), (ii) twice daily feeding (TD), (iii) OD feeding, outdoors at 38 days (ODO). In Experiment 2, the effects of feeding milk replacer (MR) as opposed to WM and age of turnout to pasture on calf performance were evaluated. The treatments applied were (i) OD feeding with WM (OD), (ii) OD feeding with milk replacer (MR) (ODMR), (iii) OD feeding with MR, outdoors at 38 days (ODMRO). Experiment 1: There were no differences (P > 0.05) in LW or average daily gain between TD and OD calves at day 80 or 410. ODO calves had lower LW at day 80 as compared to OD or TD (P < 0.001). Calf LW at day 80 was 86, 89 and 85 kg and at day 410 was 304, 309 and 316 kg for OD, TD and ODO, respectively. Milk feeding frequency or time of calf turnout had no effect on LW post calving, milk composition or 1st lactation milk yields. Experiment 2: Total LW at day 80 was higher (P < 0.05) for ODMR compared to OD or ODMRO calves. Calf LW was 87, 95, and 88 kg for OD, ODMR and ODMRO, respectively. However, LW at day 410 did not differ between treatments.This study showed that while some differences were observed in calf LW at day 80, these differences had no effect on LW at day 410 or 1st lactation milk yield. It can be concluded that calves can be successfully reared when fed OD with WM or MR, indoors and when turned out to pasture at 38 days of age.