Modeling variability of the lactation curves of cows in automated milking systems.

Historically, cow selection criteria were developed for conventional milking systems that have regular milking intervals (MI). However, in automatic milking systems (AMS), there is variability in MI within and between cows. These sources of variability provide an opportunity to identify cows with high daily milk yield (DY) and long MI. An extended MI (longer than 16 h in pasture-based systems) has a negative effect on DY. Cows that tolerate extended MI and maintain high DY can be considered more efficient than cows with low DY and long MI, or with high DY but short MI, thereby improving robotic system use. Knowledge of the behavior and parameters of lactation curves of cows in AMS could help farmers to identify cows with a specific lactational phenotype. The objective of this study was to identify individual cows with high DY and long MI within herds, which could reflect increased tolerance to milk accumulation under AMS. A database containing records for 773,483 milking events for one year (July 2016-June 2017) from 4 pasture-based AMS farms was used. Lactation curves within each herd were fitted using several mixed models including fixed effects for the parameters of the lactation curve and random cow effects. Predicted curves of average DY according to parity (multiparous and primiparous) were obtained. The best linear unbiased prediction of the random cow effect allowed us to categorize lactations as having either high or low milk production. The median MI of each lactation was then used to categorize cows as having either short or long MI. Daily yield at the peak of lactation, days to peak and 305-d cumulative milk production were used to compare the effect of DY and MI categories, as well as the DY × MI interaction. Milk production by multiparous and primiparous cows with high DY and long MI was between 35 and 45% higher than that of the low DY and short MI. From all lactations analyzed, the incidence of animals with high DY and long MI across farms was 7.5%. We have identified and quantified a new, AMS-specific, phenotype (the combination of a relatively higher DY with relatively longer MI) with potential to increase use of AMS units. Identifying more efficient animals should help generate new approaches for differential management and for selecting cows in AMS.

Physical and economic comparison of pasture-based automatic and conventional milking systems.

Automatic milking systems (AMS) have the potential to increase dairy farm productivity and profitability; however, adoption rates, particularly in pasture-based systems, have been lower than expected. The objectives of this study were to compare the physical and economic performance of pasture-based AMS with conventional milking systems (CMS) and to identify gaps for improving AMS productivity and profitability. We used data from 14 AMS and 100 CMS located in the main Australian dairy regions and collected over 3 yr (2015-2016, 2016-2017, 2017-2018). Farms within similar regions and herd sizes were compared. Results showed that all the main physical performance indicators evaluated such as milk production per cow, milk production per hectare, pasture grazed per hectare, or milk solids per full-time equivalent were similar between systems. The AMS farms had higher overhead costs such as depreciation and repairs and maintenance; however, no differences in total labor costs were observed between systems. Profitability, measured as earnings before interest and tax, operating profit margin, and return on total assets, was not significantly different between AMS and CMS. Opportunities for improving pasture utilization, labor efficiency, and robot utilization in AMS farms were identified. Improving efficiency in these areas could improve productivity and profitability of these systems, and therefore increase the interest of this technology.

Patient-Reported Outcomes after Monitoring, Surgery, or Radiotherapy for Prostate Cancer.

BACKGROUND: Robust data on patient-reported outcome measures comparing treatments for clinically localized prostate cancer are lacking. We investigated the effects of active monitoring, radical prostatectomy, and radical radiotherapy with hormones on patient-reported outcomes. METHODS: We compared patient-reported outcomes among 1643 men in the Prostate Testing for Cancer and Treatment (ProtecT) trial who completed questionnaires before diagnosis, at 6 and 12 months after randomization, and annually thereafter. Patients completed validated measures that assessed urinary, bowel, and sexual function and specific effects on quality of life, anxiety and depression, and general health. Cancer-related quality of life was assessed at 5 years. Complete 6-year data were analyzed according to the intention-to-treat principle. RESULTS: The rate of questionnaire completion during follow-up was higher than 85% for most measures. Of the three treatments, prostatectomy had the greatest negative effect on sexual function and urinary continence, and although there was some recovery, these outcomes remained worse in the prostatectomy group than in the other groups throughout the trial. The negative effect of radiotherapy on sexual function was greatest at 6 months, but sexual function then recovered somewhat and was stable thereafter; radiotherapy had little effect on urinary continence. Sexual and urinary function declined gradually in the active-monitoring group. Bowel function was worse in the radiotherapy group at 6 months than in the other groups but then recovered somewhat, except for the increasing frequency of bloody stools; bowel function was unchanged in the other groups. Urinary voiding and nocturia were worse in the radiotherapy group at 6 months but then mostly recovered and were similar to the other groups after 12 months. Effects on quality of life mirrored the reported changes in function. No significant differences were observed among the groups in measures of anxiety, depression, or general health-related or cancer-related quality of life. CONCLUSIONS: In this analysis of patient-reported outcomes after treatment for localized prostate cancer, patterns of severity, recovery, and decline in urinary, bowel, and sexual function and associated quality of life differed among the three groups. (Funded by the U.K. National Institute for Health Research Health Technology Assessment Program; ProtecT Current Controlled Trials number, ISRCTN20141297 ; ClinicalTrials.gov number, NCT02044172 .).

Dairy farmers with larger herd sizes adopt more precision dairy technologies.

An increase in the average herd size on Australian dairy farms has also increased the labor and animal management pressure on farmers, thus potentially encouraging the adoption of precision technologies for enhanced management control. A survey was undertaken in 2015 in Australia to identify the relationship between herd size, current precision technology adoption, and perception of the future of precision technologies. Additionally, differences between farmers and service providers in relation to perception of future precision technology adoption were also investigated. Responses from 199 dairy farmers, and 102 service providers, were collected between May and August 2015 via an anonymous Internet-based questionnaire. Of the 199 dairy farmer responses, 10.4% corresponded to farms that had fewer than 150 cows, 37.7% had 151 to 300 cows, 35.5% had 301 to 500 cows; 6.0% had 501 to 700 cows, and 10.4% had more than 701 cows. The results showed that farmers with more than 500 cows adopted between 2 and 5 times more specific precision technologies, such as automatic cup removers, automatic milk plant wash systems, electronic cow identification systems and herd management software, when compared with smaller farms. Only minor differences were detected in perception of the future of precision technologies between either herd size or farmers and service providers. In particular, service providers expected a higher adoption of automatic milking and walk over weighing systems than farmers. Currently, the adoption of precision technology has mostly been of the type that reduces labor needs; however, respondents indicated that by 2025 adoption of data capturing technology for monitoring farm system parameters would be increased.

Development of a new clinical mastitis detection method for automatic milking systems.

This study investigated the potential for accurate detection of clinical mastitis (CM) in an automatic milking system (AMS) using electronic data from the support software. Data from cows were used to develop the model, which was then tested on 2 independent data sets, 1 with 311 cows (same farm but from a different year) and 1 with 568 cows (from a different farm). In addition, the model was used to test how well it could predict CM 1 to 3 d before actual clinical diagnosis. Logistic mixed models were used for the analysis. Twelve measurements were included in the initial model before a backward elimination, which resulted in the following 6 measurements being included in the final model: quarter-level milk yield (MY; kg), electrical conductivity (EC; mS/cm), average milk flow rate (MF; kg/min), occurrence of incompletely milked quarters in each milking session (IM; yes or no), MY per hour (MYH; kg/h), and EC per hour (ECH; mS/cm/h) between successive milking sessions. The other 6 measurements tested but not included in the final model were peak milk flow rate (kg/min), kick-offs (yes or no) in each milking session, lactation number, days in milk (d), blood in milk (yes or no), and a calculated mastitis detection index used by DeLaval (DelPro software; DeLaval International AB, Tumba, Sweden). All measurements were assessed to determine their ability to detect CM as both individual variables and combinations of the 12 above-mentioned variables. These were assessed by producing a receiver operating characteristic curve and calculating the area under the curve (AUC) for each model. Overall, 9 measurements (i.e., EC, ECH, MY, MYH, MF, IM, peak flow rate, lactation number, and mastitis detection index) had significant mastitis detection ability as separate predictors. The best mastitis prediction was possible by incorporating 6 measurements (i.e., EC, ECH, MY, MYH, MF, and IM) as well as the random cow and quarter effects in the model, resulting in 90% sensitivity and 91% specificity with excellent AUC (0.96). Assessment of the model was found to produce robust results (AUC >0.9) in different data sets and could detect CM with reductions in sensitivity and specificity with increasing days before actual diagnosis. This study demonstrated that improved mastitis status prediction can be achieved by using multiple measurements, and new indexes based on that are expected to result in improved accuracy of mastitis alerts, thereby improving the detection ability and utility on farm.

Systematic review and meta-analysis of the role of metronidazole in post-haemorrhoidectomy pain relief.

AIM: Conventional haemorrhoidectomy is still considered the reference standard for the management of severe or recurrent haemorrhoids. Pain is reported by patients to be the most common postoperative complication. Although the literature lacks a consensus on its effectiveness, metronidazole is often used to reduce postoperative pain. We have performed a meta-analysis of all randomized controlled trials (RCTs) that investigated the use of metronidazole for pain relief after haemorrhoidectomy. METHOD: A systematic review was undertaken in accordance with the PRISMA protocol using the MESH headings 'haemorrhoidectomy', 'hemorhoidectomy', 'hemorrhoidectomy', 'haemorrhoid', 'metronidazole', 'Flagyl® ' 'antibiotic' and 'pain'. The search returned 421 articles of which eight were RCTs suitable for inclusion in the review with a total population of 437 patients. The outcomes of interest were postoperative pain intensity on days 1, 2 and 7 and on first defaecation as measured using a visual analogue scale. RESULTS: The meta-analysis demonstrated a significant reduction in postoperative pain for patients treated with metronidazole with a reduced mean difference for the metronidazole group on day 1 of -1.42 (95% CI: -2.14 to -0.69, P = 0.0001), on day 2 of -1.43 (95% CI: -2.45 to -0.40, P = 0.006) and on day 7 of -2.40 (95% CI: -3.10 to -1.71, P < 0.00001). Pain on first defaecation was likewise reduced with a mean difference of -1.38 (95% CI: -2.15 to -0.60, P = 0.0005). Limitations of this study include variation in the grade of haemorrhoids treated and variability in the quality of included studies. CONCLUSION: Metronidazole is a cheap, safe and effective intervention for reducing postoperative pain following conventional haemorrhoidectomy.

Meta-analysis of closure of the fascial defect during laparoscopic incisional and ventral hernia repair.

BACKGROUND: Laparoscopic incisional and ventral hernia repair (LIVHR) is being used increasingly, with reported outcomes equivalent to those of open hernia repair. Closure of the fascial defect (CFD) is a technique that may reduce seroma formation and bulging after LIVHR. Non-closure of the fascial defect makes the repair of larger defects easier and reduces postoperative pain. The aim of this systematic review was to determine whether CFD affects the rate of adverse outcomes, such as recurrence, pseudo-recurrence, mesh eventration or bulging, and the rate of seroma formation. METHODS: A systematic search was performed of PubMed, Ovid, the Cochrane Library, Google Scholar and Scopus to identify RCTs that analysed CFD with regard to rates of adverse outcomes. A meta-analysis was done using fixed-effect methods. The primary outcome of interest was adverse events. Secondary outcomes were seroma, postoperative pain, mean hospital stay, mean duration of operation and surgical techniques employed. RESULTS: A total of 16 studies were identified involving 3638 patients, 2963 in the CFD group and 675 in the non-closure of facial defect group. Significantly fewer adverse events were noted following CFD than non-closure (4·9 per cent (79 of 1613) versus 22·3 per cent (114 of 511)), with a combined risk ratio (RR) of 0·25 (95 per cent c.i. 0·18 to 0·33; P < 0·001). CFD resulted in a significantly lower rate of seroma (2·5 per cent (39 of 1546) versus 12·2 per cent (47 of 385)), with a combined RR of 0·37 (0·23 to 0·57; P < 0·001), and shorter duration of hospital stay. No significant difference was noted in postoperative pain. CONCLUSION: CFD during LIVHR reduces the rate of seroma formation and adverse hernia-site events.

Differences in Voluntary Cow Traffic between Holstein and Illawarra Breeds of Dairy Cattle in a Pasture-based Automatic Milking System.

Automatic milking systems (AMS) rely upon voluntary cow traffic (the voluntary movement of cattle around a farm) for milk harvesting and feed consumption. Previous research on conventional milking systems has shown differences between dairy cow breeds for intake and milk production, however, the ability to manipulate voluntary cow traffic and milking frequency on AMS farms through breed selection is unknown. This study investigated the effect of breed (Holstein Friesian versus Illawarra) on voluntary cow traffic as determined by gate passes at the Camden AMS research farm dairy facility. Daily data on days in milk, milk yield, gate passes and milking frequency for 158 Holstein Friesian cows and 24 Illawarra cows were collated by month for the 2007 and 2008 years. Illawarra cows had 9% more gate passes/day than Holstein cows over the duration of the study; however, the milking frequency and milk yield of both breeds were similar. Gate passes were greatest for both breeds in early lactation and in the winter (June to August) and summer (December to February) seasons. These findings highlight an opportunity to translate increased voluntary cow movement associated with breed selection into increased milking frequencies, milk production and overall pasture-based AMS performance.

Impact of disclosure of radiographic test results on quality of life among patients with hernias: a randomized controlled trial.

PURPOSE: Hernias noted on radiographic imaging are common. We aimed to determine if informing patients of the presence of a clinically apparent or occult hernia on imaging would change their abdominal wall quality of life (AW-QOL). METHODS: This study was registered on clinicaltrials.gov (NCT04355819) in April 2020. Patients with a ventral hernia on elective CT abdomen/pelvis were enrolled. Patients underwent standardized abdominal examination by surgeons, and completed the modified Activities Assessment Scale, a validated, hernia-specific AW-QOL survey. On this scale, 1 is poor AW-QOL, 100 is perfect, and the minimally clinically important difference is five for a minor change. Patients were randomized to complete the one-year follow-up survey before or after being informed of the presence of a hernia on their imaging results. Primary outcome was follow-up AW-QOL adjusted for baseline AW-QOL. RESULTS: Of 169 patients randomized, 126 (75%) completed follow up at one-year. Among patients with occult hernias, those who completed the follow-up survey after being informed of having a hernia had a lower follow-up AW-QOL (mean difference - 7.6, 95% CI = - 20.8 to 5.7, p = 0.261) compared to those who completed the survey before being informed. Conversely, for patients with clinical hernias, those who completed the survey after being informed had higher adjusted follow-up AW-QOL (mean difference 10.3, 95% CI = - 3.0 to 23.6, p = 0.126) than those that completed it after. CONCLUSION: Conveying findings of hernias found on CT imaging can influence patients' AW-QOL. Future research should focus on identifying and addressing patients' concerns after disclosure of CT results.

Cost-effectiveness of farm interventions for reducing the prevalence of VTEC O157 on UK dairy farms.

A randomized control trial on verocytotoxigenic Escherichia coli (VTEC)-infected farms found evidence that: (1) keeping animals in the same group; (2) maintaining dry bedding; (3) preventing direct contact with neighbouring cattle; and (4) maintaining a closed herd, were associated with a reduced risk of infection in youngstock aged 3­18 months. This study evaluated these interventions using a cost-effectiveness framework for UK dairy farms. Keeping animals in the same group was considered to have negligible cost and was feasible for herds containing over 77 dairy cows. Assuming equal efficacy of the remaining interventions, preventing direct contact between neighbouring cattle is most cost-effective with a median annual cost of £2.76 per cow. This compares to £4.18 for maintaining dry bedding and £17.42 for maintaining a closed herd using quarantine procedures. Further model validation and exploration of other potential benefits are required before making policy decisions on VTEC control.

Comparison of 2 systems of pasture allocation on milking intervals and total daily milk yield of dairy cows in a pasture-based automatic milking system.

Cows milked in pasture-based automatic milking systems (AMS) have greater milking intervals than cows milked in indoor AMS. Long milking intervals greater than 16h have a negative effect on milk yield and udder health. The impact of 2 systems of pasture allocation in AMS on milking interval and yield was investigated at the FutureDairy AMS research farm (Elizabeth Macarthur Agricultural Institute, New South Wales Department of Primary Industries, Camden, New South Wales, Australia) in late November to early December 2010. Two- (2WG) versus 3-way grazing (3WG) allocations per 24-h period were compared in a field study to test the hypothesis that an increase in the frequency of pasture allocation would reduce the milking interval and, therefore, increase milking frequency. The study involved the entire milking herd of 145 cows, with (mean ± SD) DIM=121±90d, 7-d average milking frequency=1.52±0.41 milkings/cow per day, and 7-d average milk yield=21.3±7.6kg/cow per day. Cows were milked using 2 DeLaval VMS milking units (DeLaval International AB, Tumba, Sweden). Cows in the 3WG treatment had 31% reduced milking interval, 40% greater milking frequency, and 20% greater daily milk production compared with 2WG. Increased milking frequency and milk production for 3WG was associated with greater utililization levels of the AMS milking units throughout the day. These results support the recommendation that, wherever possible, farmers installing AMS should incorporate sufficient infrastructure to accommodate 3WG, which provides additional flexibility with managing extremely long (and short) milking intervals.

Effect of pre- versus postmilking supplementation on traffic and performance of cows milked in a pasture-based automatic milking system.

Cows milked in a pasture-based automatic milking system tend to have a lower daily milking frequency in comparison with cows milked in indoor systems. Milking events with intervals beyond 16h have been reported to have a negative effect on milk yield and udder health, and therefore it is important to minimize their occurrence. As feed is the main incentive to encourage cow traffic around the system, a study was conducted to compare pre- (PRE) versus postmilking (POST) supplementary feed placement strategies in a pasture-based automatic milking system. We hypothesized that PRE cows would have a stronger incentive to walk voluntarily from the paddock to the dairy facility to get milked (due to the reward being more immediate), thereby reducing their milking interval and increasing daily milking frequency and milk yield. The PRE cows returned to the dairy facility sooner (PRE=11.9 vs. POST=13.27h) but had longer milking intervals (PRE=15.3 vs. POST=14.28h). This was due to the additional time spent in the prefeeding area (PRE=56 versus POST=23min) combined with a longer average time spent in the premilking waiting yard (PRE=97 versus POST=77min). Treatment did not affect daily milk yield per cow. The result of this study demonstrates the potential of manipulating feeding management strategies to influence cow behavior and traffic in voluntary milking systems.

Natural history of occult hernias in adults at a safety-net hospital.

PURPOSE: Occult hernias, hernias seen on radiologic imaging but not felt on physical exam, are common. Despite their high prevalence, little is known about the natural history of this finding. Our aim was to determine and report on the natural history of patients with occult hernias including the impact on abdominal wall quality of life (AW-QOL), need for surgery, and risk of acute incarceration/strangulation. METHODS: This was a prospective cohort study of patients who underwent a computed tomography (CT) abdomen/pelvis scan from 2016 to 2018. Primary outcome was change in AW-QOL using the modified Activities Assessment Scale (mAAS), a hernia-specific, validated survey (1 = poor, 100 = perfect). Secondary outcomes included elective and emergent hernia repairs. RESULTS: A total of 131 (65.8%) patients with occult hernias completed follow-up with a median (IQR) of 15.4 (22.5) months. Nearly half of these patients (42.8%) experienced a decrease in their AW-QOL, 26.0% were unchanged, and 31.3% reported improvement. One-fourth of patients (27.5%) underwent abdominal surgery during the study period: 9.9% were abdominal procedures without hernia repair, 16.0% involved elective hernia repairs, and 1.5% were emergent hernia repairs. AW-QOL improved for patients who underwent hernia repair (+ 11.2 ± 39.7, p = 0.043) while those who did not undergo hernia repair experienced no change in AW-QOL (- 3.0 ± 35.1). CONCLUSION: When untreated, patients with occult hernias on average experience no change in their AW-QOL. However, many patients experience improvement in AW-QOL after hernia repair. Additionally, occult hernias have a small but real risk of incarceration requiring emergent repair. Further research is needed to develop tailored treatment strategies.

Optimising profitability and productivity of pasture-based dairy farms with automatic milking systems.

There is a large variability in profitability and productivity between farms operating with automatic milking systems (AMS). The objectives of this study were to identify the physical factors associated with profitability and productivity of pasture-based AMS and quantify how changes in these factors would affect farm productivity. We utilised two different datasets collected between 2015 and 2019 with information from commercial pasture-based AMS farms. One contained annual physical and economic data from 14 AMS farms located in the main Australian dairy regions; the other contained monthly, detailed robot-system performance data from 23 AMS farms located across Australia, Ireland, New Zealand, and Chile. We used linear mixed models to identify the physical factors associated with different profitability (Model 1) and partial productivity measures (Model 2). Additionally, we conducted a Monte Carlo simulation to evaluate how changes in the physical factors would affect productivity. Our results from Model 1 showed that the two main factors associated with profitability in pasture-based AMS were milk harvested/robot (MH; kg milk/robot per day) and total labour on-farm (full-time equivalent). On average, Model 1 explained 69% of the variance in profitability. In turn, Model 2 showed that the main factors associated with MH were cows/robot, milk flow, milking frequency, milking time, and days in milk. Model 2 explained 90% of the variance in MH. The Monte Carlo simulation showed that if pasture-based AMS farms manage to increase the number of cows/robot from 54 (current average) to âˆ¼ 70 (the average of the 25% highest performing farms), the probability of achieving high MH, and therefore profitability, would increase from 23% to 63%. This could make AMS more attractive for pasture-based systems and increase the rate of adoption of the technology.

Ordered accumulation of mutations in HIV protease confers resistance to ritonavir.

Analysis of the HIV protease gene from the plasma of HIV-infected patients revealed substitutions at nine different codons selected in response to monotherapy with the protease inhibitor ritonavir. Mutants at valine-82, although insufficient to confer resistance, appeared first in most patients. Significant phenotypic resistance required multiple mutations in HIV protease, which emerged subsequently in an ordered, stepwise fashion. The appearance of resistance mutations was delayed in patients with higher plasma levels of ritonavir. Early mutants retained susceptibility to structurally diverse protease inhibitors, suggesting that dual protease inhibitor therapy might increase the duration of viral suppression.

Contralateral exploration and repair of occult inguinal hernias during laparoscopic inguinal hernia repair: systematic review and Markov decision process.

BACKGROUND: Contralateral clinically occult hernias are frequently noted at the time of laparoscopic unilateral inguinal hernia repair. There is no consensus on the role of contralateral exploration and repair. This systematic review assessed the safety and efficacy of operative repair of occult contralateral inguinal hernias found during unilateral repair. METHODS: PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched from inception to February 2020. Adults diagnosed with a unilateral inguinal hernia undergoing laparoscopic repair were included. The primary outcome was the incidence of occult contralateral hernias. Summative outcomes of operative and expectant management were reported along with development of a Markov decision process. RESULTS: Thirteen studies (1 randomized trial, 12 observational cohorts) with 5000 patients were included. The incidence of occult contralateral inguinal hernias was 14.6 (range 7.3-50.1) per cent. Among patients who underwent repair, 10.5 (4.3-17.0) per cent experienced a postoperative complication. Of patients managed expectantly, 29 per cent later required elective repair for symptoms. Mean follow-up was 36 (range 2-218) months. Using a Markov decision process, it was calculated that, for every 1000 patients undergoing unilateral inguinal hernia repair, contralateral exploration would identify 150 patients with an occult hernia. Repair would result in 15 patients developing a postoperative complication and 105 undergoing unnecessary repair. Alternatively, expectant management would result in 45 patients requiring subsequent repair. CONCLUSION: Contralateral repair is not warranted in patients with occult hernias diagnosed at the time of elective hernia repair. The evidence is largely based on observational studies at high risk of bias.

Productive, economic and risk assessment of grazing dairy systems with supplemented cows milked once a day.

Milking cows once a day (OAD) is a herd management practice that may help to reduce working effort and labour demand in dairy farms. However, a decrease in milk yield per cow occurs in OAD systems compared with twice a day (TAD) systems and this may affect profitability of dairy systems. The objective of this study was to assess productive and economic impact and risk of reducing milking frequency from TAD to OAD for grazing dairy systems, using a whole-farm model. Five scenarios were evaluated by deterministic and stochastic simulations: one scenario under TAD milking (TADAR) and four scenarios under OAD milking. The OAD scenarios assumed that milk yield per cow decreased by 30% (OAD30), 24% (OAD24), 19% (OAD19) and 10% (OAD10), compared with TADAR scenario, based on experimental and commercial farms data. Stocking rate (SR) was increased in all OAD scenarios compared to TADAR and two levels of reduction in labour cost were tested, namely 15% and 30%. Milk and concentrate feeds prices, and pasture and crop yields, were allowed to behave stochastically to account for market and climate variations, respectively, to perform risk analyses. Scenario OAD10 showed similar milk yield per ha compared with TADAR, as the increased SR compensated for the reduction in milk yield per cow. For scenarios OAD30, OAD24 and OAD19 the greater number of cows per ha partially compensated for the reduction of milk yield per cow and milk yield per ha decreased 21%, 15% and 10%, respectively, compared with TADAR. Farm operating profit per ha per year also decreased in all OAD scenarios compared with TADAR, and were US$684, US$161, US$ 303, US$424 and US$598 for TADAR, OAD30, OAD24, OAD19, OAD10, respectively, when labour cost was reduced 15% in OAD scenarios. When labour cost was reduced 30% in OAD scenarios, only OAD10 showed higher profit (US$706) than TADAR. Stochastic simulations showed that exposure to risk would be higher in OAD scenarios compared with TADAR. Results showed that OAD milking systems might be an attractive alternative for farmers who can either afford a reduction in profit to gain better and more flexible working conditions or can minimise milk yield loss and greatly reduce labour cost.