Pasture-based Dairy Research Articles

DESTiny, an online farm-wide tool to estimate the net carbon emissions of a pasture-based dairy farms in South Africa

The dairy farming industry is an important contributor to both South Africa’s economy and food security. However, dairy in South Africa, like elsewhere in the world, has come under scrutiny because of animal welfare concerns and contributions to greenhouse gas (GHG) emissions. To address GHG mitigation, we have constructed a farm-level system dynamics model to assess both the emissions, and capture and storage of carbon (C) on farms, to determine whether farms are net emitters of C (i.e., sources) or sequestrators (i.e., sinks). We have considered nutrient flows, the type and volume of feed, the effluent management system, various parameters relating to the herd dynamics, and the overall effect on the farm economy. The resulting online Dairy Environment Sustainability Tool (DESTiny) can help dairy farmers adopt sustainable practices, as well as improve competitiveness and financial sustainability while reducing the farm’s emissions profile, thereby building value-chain and consumer trust. DESTiny can be considered a science-informed evidence-based tool for estimating, monitoring and understanding nutrient and C flows in dairy production systems. It is also a web-based tool (see https://assetresearch.org.za/destiny-tool/) with a user-interface which allows remote users, researchers, practitioners, farmers and technicians ease of access while integrating the system dynamics models with on-farm realities.

Cow Culling Rates and Causes in 12 Pasture-Based Dairy Herds in Southern Uruguay, a Pilot Study

Cow Culling Rates and Causes in 12 Pasture-Based Dairy Herds in Southern Uruguay, a Pilot Study

Milk yield and pasture nutrient availability associated with milking order in commercial dairy herds

Context On pasture-based dairy farms, herd behavioural dynamics result in a milking order that remains consistent over time. Previous research has demonstrated that cows that are consistently early in the milking order routinely access pasture of greater biomass and nutrient density than do later-milked cows, because they access the paddock first. This effect is likely to explain why early cows commonly produce more milk than do later cows. We hypothesised that in commercial dairy herds, milk yield would decline as milking order progressed, and there would be a reduction in pasture mass and nutritive value before the last cows returned to the paddock. Aims This study aimed to validate observations previously demonstrated under controlled experimental conditions, in commercial dairy herds in Gippsland, Victoria. Methods This research was repeated across three commercial farms, with four grazing sessions observed per farm. Cows were milked twice daily, with daily individual milk yields and milking times obtained. Pasture measurements were collected pre-grazing, hourly for the first 3 h of grazing after the morning milking (while cows progressively entered the paddock), and post-grazing after the cows exited the paddock. At each sampling, pasture mass was estimated using a calibrated rising-plate metre, and pasture samples were collected for analyses of nutritive characteristics. Key results Milking order was consistent, and the last cows produced on average 4.7 L/cow.day less milk than did the first cows. As grazing progressed, pasture mass, crude protein concentrations and metabolisable energy declined and fibre concentrations increased. Conclusions This study demonstrated a decrease in pasture mass and nutrient density as grazing progressed. The earliest cows had access to more pasture of higher nutrient density and produced more milk than did later-milked cows. Implications This study validated that the milk yield of cows in commercial herds is influenced by milking order, which is likely to be mediated at least in part by the quantity and nutrient density on offer to earlier versus later-milked cows. Other factors may also influence milking order and milk yield, but these factors were not accounted for in this research. Future research should focus on mitigation strategies to negate this effect by improving nutrient intake of later-milked cows.

The effect of meloxicam at the time of treatment of hoof-horn lameness in pasture-grazing dairy cattle on time to lameness soundness, pregnancy risk and time to conception; a randomized control trial.

The aims of this study were to assess the effect of meloxicam at the time of lameness treatment for hoof-horn (HH) lesions in dairy cattle on 1) time to lameness soundness post trimming and block application and 2) reproductive success Five seasonal-calving pasture-based dairy farms located in the Waikato region of New Zealand were enrolled into a randomized clinical interventional trial. Farmers were tasked with identifying lame animals over a period of approximately -4 to 6 weeks relative to the herd start of mating (HSM), with lameness subsequently confirmed with lameness score (LS) by trained technicians (0-3 scale, where ≥2 are considered lame). Animals with a LS ≥2 were examined by a veterinarian who then enrolled animals if they presented lame with HH (white-line or sole) lesions. This same veterinarian then provided therapeutic hoof trimming, and application of wooden blocks, to the enrolled lame animals. Randomization into either meloxicam (0.5 mg/kg sub-cutaneous) or negative control groups was conducted after trimming, with animals blocked by farm and lesion. Following lameness treatment, animals were lameness scored at a median interval of every 4 d until sound (LS = 0), with scoring occurring regardless of block retention status; blocks were not removed at any stage. Animals had conception date and pregnancy status confirmed via rectal ultrasound. Outcomes were number of days to soundness (animals may still have block on) and number of days from HSM to conception, and binary outcomes of pregnant within 6 weeks of the breeding period and final pregnancy status. Cox proportional hazard methods were used to analyze the time-to-event outcomes, with binary outcomes analyzed using multivariable logistic regression methods. A total of 241 animals were enrolled, 123 into the meloxicam group and 118 into the control group. The majority of lesions were described as white-line (225; 93%), with 207 (86%) animals receiving wooden blocks on the non-lame hoof. No improvement in the time to soundness was reported between animals in the 2 treatment groups (hazard ratio 0.78; 95% CI 0.56 - 1.03 for meloxicam treated animals compared with control animals), with most scoring events occurring with a block present. From the 229 animals with reproductive outcome data (117 meloxicam treated and 112 control treated), the hazards of conception in meloxicam treated animals were 1.42 (95% CI 1.06 - 1.90) times that for the control animals. Meloxicam treated lame animals had 15% greater predicted probabilities of conceiving within the first 6 weeks of the breeding period (P = 0.037) and final pregnancy status (P = 0.019), respectively, compared with control lame animals. The addition of meloxicam to the treatment regimen of lame dairy cattle with HH lesions can significantly improve reproductive outcomes, despite no apparent difference in time to soundness.

An investigation into the factors associated with pregnancy associated glycoproteins in milk in seasonal-calving pasture-based dairy cows.

Pregnancy associated glycoproteins (PAG) are secreted by trophoblast giant cells, and are detectable in blood and milk within the first month of gestation. The PAG concentration in blood and milk is believed to be one indicator of placental function and predictive of pregnancy maintenance. The objective of this retrospective study was to investigate factors associated with milk PAG S-N profiles in cows managed under a seasonal calving, pasture-based production system. Spring-calving dairy cows (n = 496) located in 3 Teagasc Research farms in Ireland were enrolled in the study. Milk samples were collected weekly from each cow from wk 5 to 21 after artificial insemination (AI) to determine milk PAG S-N values. Body condition score was measured every 2 weeks on a scale of 1 to 5 with 0.25 increments. Only cows that conceived to first AI and maintained pregnancy were retained for the final analysis (n = 247). Mixed models were used to evaluate the fixed effects of week after AI, BCS, dam fertility index (FI) and milk index (MI), milk yield category, sire, parity, calf sex and calf birthweight on weekly milk PAGS-N profile, initial peak PAG, nadir PAG and post nadir recovery peak PAG. Week after AI was associated with milk PAG S-N values, with initial peak values observed on (mean and 95% CI) wk 6.4 ([6.2, 6.5]) after AI, nadir values on wk 8.6 ([8.55, 8.90]) after AI followed by recovery thereafter. We observed associations between parity, dam FI, milk yield, sire of the gestating embryo/fetus, fetal sex, and full-term calf birthweight with different aspects of the PAG S-N profile. Cows with the greatest FI had greater milk PAG S-N values at wk 5 and 6 after AI compared with cows with intermediate FI and least FI. There was also an association with parity because parity 1 cows had greater milk PAG S-N values than parity 2 and parity 3 cows during the initial peak and nadir stages of the PAG profile. An effect of sire on nadir milk PAG S-N values was observed, with PAG S-N values ranging from 0.5 to 1.2 between sires. In summary, milk PAG concentrations were associated with dam genetic merit, phenotypic milk production, and fetal characteristics. Assuming a correlation between milk PAG S-N values and placental function, these data provide evidence for an effect of genetic selection for fertility traits on placental development and/or function.

Transition cow health and management in pasture-based dairy herds: A farmers' survey.

Seasonal-calving pasture-based systems characterize Irish dairy production. During the dry period, cows are housed and offered predominantly grass silage, providing unique transition cow management opportunities. This study aimed to describe transition period disease incidence and management strategies reported by farmers, and to evaluate their associations with herd size and calving pattern to inform and guide research activities and national advisory. An online survey distributed amongst 3,899 Teagasc Technical Dairy Advisory clients yielded 525 responses suitable for analysis. Results are presented for all respondents, by herd size and by the two most common calving systems (spring- [84.3%; 439/521] and split-calving [12.9%; 67/521]). Disease incidence was reportedly highest in cows within their first 3 weeks postpartum (58%; 299/519), in cows calving at the end of the calving season (48%; 245/510) and in multiparous cows (52%; 266/513). Respondents reported treating >3% of their herd for milk fever (23%; 120/521) and retained placenta (13%; 68/518), and <1% of their herd for grass tetany (82.6%; 419/507) and ketosis (72.7%; 368/506). Regarding management, dry cow body condition monitoring (73%; 365/497), dry cow mineral supplementation (61%; 304/497), and Ca supplementation at calving (61%; 314/487) were most commonly reported. Other milk fever prevention strategies supported by research in other production systems were not commonly reported (low K [20%; 101/497] and negative dietary cation-anion difference diet [6%; 31/497]). The odds of reporting keeping records of antibiotic treatment for milk fever were higher (OR = 3.20) for farmers from small compared to large herds. In conclusion, responses to our survey suggest that milk fever is a transition cow health concern in Irish dairy farms. Efforts should be devoted to enhance farmers' uptake of existing research-supported prophylactic strategies for milk fever and to optimize commonly reported management strategies in the Irish dairy production context.

Characterization of In Situ Ruminal Degradation of Crude Protein and Individual Amino Acids from Ryegrass

In temperate pasture-based dairy systems, ryegrass (Lolium perenne L.) is a key forage due to its high crude protein (CP) content, yet its rapid ruminal degradation could limit the supply of rumen-undegraded protein and essential amino acids (EAAs) to dairy cows. This study aimed to investigate the in situ ruminal degradability of CP and individual amino acids (AAs) in fresh ryegrass at the vegetative stage. Three second-parity, rumen-cannulated Holstein Friesian cows (487 kg body weight, 16.5 kg milk/day) were used for the incubation of ryegrass samples collected in different seasons at the vegetative stage. The degradation kinetics were assessed using the Ørskov and McDonald model, with mathematical corrections for microbial contamination. Results showed that the effective degradability (ED) of AAs was generally higher than that of CP (p &lt; 0.05), exceeding 2%, and that some EAAs, particularly lysine, exhibited an ED up to 5.5% greater than CP (p &lt; 0.05). These differences underscore the need for caution when using CP as a proxy for AA degradation in dietary formulations. Given the high degradability of ryegrass AAs, it would be important to monitor and adjust their supply in diets with high ryegrass inclusion to prevent potential deficiencies that could impair milk production and reduce feed efficiency.

120 Juvenile in vitro fertilization embryo transfer in seasonal pasture-based dairy systems

120 Juvenile in vitro fertilization embryo transfer in seasonal pasture-based dairy systems

Use of conjoint analysis to weight biosecurity practices on pasture-based dairy farms to develop a novel audit tool-BioscoreDairy.

Risk assessments are important tools to identify deficits in biosecurity management practices. A major strength of some existing tools is that they facilitate cross-country comparisons. However, a weakness is their failure to account for unique intra-national farming enterprise structures such as, for example, pasture-based dairying. Currently, there are no suitable biosecurity risk assessment tools applicable to pasture-based dairying as practiced in Ireland. In addition to a need for enterprise-specific biosecurity risk assessment tools, the weighting of risk scores generated by these tools needs to be context-specific to ensure validity in assessing biosecurity risks in the farming sector of interest. Furthermore, existing biosecurity audits rely exclusively on respondent recall to answer questions about management practices. To address each of these limitations of existing biosecurity risk assessment tools we developed and optimised a new biosecurity risk assessment tool (BioscoreDairy) designed to assess the biosecurity status of pasture-based dairy farms in Ireland. It consists of two parts, a biosecurity questionnaire and a cattle movement records audit. A questionnaire was developed on biosecurity management practices appropriate for a pasture-based dairy system. Multiple national expert groups were leveraged to provide weightings for the different management practices in the questionnaire using the best-worst scaling methodology of MaxDiff. The results of this process provided a numerical categorisation that could then be used to assign scores to the individual biosecurity management practices. These practices were grouped into three biosecurity areas; risk of disease entry, speed of disease spread and diagnosis of infection. Within each of these three areas, a traffic light system was used to compare a farm's biosecurity risks to other similar farms-least risk (green; within the top third of farms), concerning practice (amber; middle third) and worst practice or greatest risk (red; lowest third). In addition to these scores, the cattle introduction profile of a herd over the previous 3 years, based on nationally recorded data, was audited, compared amongst dairy farm enterprise subtypes, and included in the BioscoreDairy report. BioscoreDairy is therefore the first biosecurity risk assessment tool tailored to pasture-based dairy farm systems, both for individual farm reporting and for benchmarking against comparable farms.

Advancing carbon sequestration and nutrient management in the South African dairy industry for sustainable growth

The dairy industry in South Africa is currently grappling with significant challenges, including escalating costs and diminishing profit margins. However, these difficulties also create a pivotal opportunity for the sector to embrace sustainable practices that not only enhance environmental stewardship but also encourage economic resilience. A crucial step in this transition is to dispel prevalent misconceptions about the industry’s environmental footprint and to highlight its positive contributions to sustainable agricultural practices. Farmers are encouraged to adopt innovative strategies that enhance soil health and reduce their ecological impact. This review focuses on essential factors influencing nutrient management and the processes that contribute to soil carbon enhancement. Effective management is crucial for the sustainability of pasture-based dairy systems, as herbage biomass significantly influences nutrient cycling and soil organic matter accumulation. For instance, well-managed pastures with high biomass can efficiently recycle nutrients from manure, enhancing plant growth. This process contributes to soil organic carbon buildup, which aids in carbon sequestration. In contrast, poor nutrient management can lead to nutrient imbalances and lower herbage production, reducing carbon storage potential. Moreover, the movement of nutrients below the surface is a critical pathway for enhancing soil health and promoting ecological balance. By implementing sustainable practices and refining nutrient stewardship strategies, pasture-based dairy farmers can significantly advance their sustainability goals. This includes recognizing the broader implications of soil health on farm productivity and environmental resilience, as well as the potential for improved biodiversity.

Animal behaviour and dietary preference of dairy cows grazing binary and diverse pastures under the leaf regrowth stage defoliation criterion

In New Zealand, intensively managed pasture-based dairy systems rely on binary pastures mostly comprised of Lolium perenne L. and Trifolium repens L.. More frequent and extreme climatic events have been negatively affecting the persistency and production of these pastures, which now present increased seasonality, with marked peaks and troughs of production throughout the year. Diversification of plant species offers a solution to deal with increased seasonality. However, little is known about animal behaviour and dietary preferences of dairy cows grazing diverse pastures. The present study aimed to assess the grazing preferences of dairy cows when unrestrictedly offered binary (L. perenne and T. repens; Bi) and diverse pastures (L. perenne, Bromus valdivianus Phil., Dactylis glomerata L. and T. repens; Mix) subjected to three different leaf regrowth stage (LS) defoliation criteria. Secondarily, the study aimed to determine the main plant-related drivers for any potential animal preference. The treatments were MixLp (defoliated at L. perenne LS), BiLp (defoliated every time MixLp was defoliated), MixBv (defoliated at B. valdivianus LS) and BiBv (defoliated every time MixBv was defoliated), MixDg (defoliated at D. glomerata LS) and BiDg (defoliated every time MixDg was defoliated). Dairy cattle were evaluated over five agricultural seasons. The response variables were grazing time and location, bite rate, animal behavioural activity, pre-grazing herbage mass, undisturbed sward height, lamina:stem ratio, crude protein, metabolisable energy, organic matter digestibility, non-structural carbohydrates, neutral detergent fibre and lignin. Where significant differences were found, binary pastures presented lower sward height and higher non-structural carbohydrate content in comparison to the diverse pastures under the same LS defoliation criteria. However, no significant differences were found in the percentage of time that cows spent grazing both pastures. Season was the greatest contributor to the proportion variation found in all response variables, with values ranging from 47.55 % up to 88.77 %. In winter and spring, cows modulated their grazing behaviour (proportional time spent grazing, ruminating, or idling), investing more time actively grazing pastures under L. perenne LS interval of defoliation (2.5–3.0 LS), the criterion which resulted in shorter grazing rotations. This study allowed us to understand the suitability of diverse pastures from an animal perspective, and highlighted that independent of the pasture type, the positive productive and nutritional effects of defoliation management based on the LS may also extend themselves to positive outcomes in animal preference, interpreted as the percentage of time dairy cows spend grazing rather than ruminating or idling across and within seasons.

Assessing antimicrobial resistance in pasture-based dairy farms: a 15-month surveillance study in New Zealand.

Antimicrobial resistance is a global public and animal health concern. Antimicrobial resistance genes (ARGs) have been detected in dairy farm environments globally; however, few longitudinal studies have utilized shotgun metagenomics for ARG surveillance in pasture-based systems. This 15-month study aimed to undertake a baseline survey using shotgun metagenomics to assess the relative abundance and diversity of ARGs in two pasture-based dairy farm environments in New Zealand with different management practices. There was no statistically significant difference in overall ARG relative abundance between the two dairy farms (P = 0.321) during the study period. Compared with overseas data, the relative abundance of ARG copies per 16S rRNA gene in feces (0.08-0.17), effluent (0.03-0.37), soil (0.20-0.63), and bulk tank milk (0.0-0.12) samples was low. Models comparing the presence or absence of resistance classes found in >10% of all feces, effluent, and soil samples demonstrated no statistically significant associations (P > 0.05) with "season," and only multi-metal (P = 0.020) and tetracycline (P = 0.0003) resistance were significant at the "farm" level. Effluent samples harbored the most diverse ARGs, some with a recognized public health risk, whereas soil samples had the highest ARG relative abundance but without recognized health risks. This highlights the importance of considering the genomic context and risk of ARGs in metagenomic data sets. This study suggests that antimicrobial resistance on pasture-based dairy farms is low and provides essential baseline ARG surveillance data for such farming systems.IMPORTANCEAntimicrobial resistance is a global threat to human and animal health. Despite the detection of antimicrobial resistance genes (ARGs) in dairy farm environments globally, longitudinal surveillance in pasture-based systems remains limited. This study assessed the relative abundance and diversity of ARGs in two New Zealand dairy farms with different management practices and provided important baseline ARG surveillance data on pasture-based dairy farms. The overall ARG relative abundance on these two farms was low, which provides further evidence for consumers of the safety of New Zealand's export products. Effluent samples harbored the most diverse range of ARGs, some of which were classified with a recognized risk to public health, whereas soil samples had the highest ARG relative abundance; however, the soil ARGs were not classified with a recognized public health risk. This emphasizes the need to consider genomic context and risk as well as ARG relative abundance in resistome studies.

Assessing the dry matter intake and enteric methane emissions of pre-partum dairy cows offered grass clover or grass-only silage from two different silage systems

Over the winter period, the low grass growth and availability in pasture-based dairy systems results in animals being housed and predominantly fed a diet of grass silage. There is limited availability of methane (CH4) data evaluating the impact of forage type on dairy cows over the pre-partum period. The objective of the current experiment was to evaluate the impact of feeding grass clover (GC) silage and grass-only (GO) silage on the dry matter intake (DMI) and enteric CH4 emissions of dairy cows pre-partum. A complete randomised block design was utilised for the 6-week experiment over two winter periods: from December 2020 to January 2021 and from December 2021 to January 2022. In each year, 30 non-lactating pregnant dairy cows were randomly allocated to two treatments (n = 15). In both years, cows in the GC treatment were offered grass clover bale silage, while cows in the GO treatment were offered grass-only pit silage. The DMI and gaseous emissions of individual animals were monitored daily using Hokofarm RIC (roughage intake control) feed stations and the GreenFeed technology. GC silage consistently had greater (p&amp;lt; 0.05) organic matter (OM) digestibility and lower (p&amp;lt; 0.05) neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents when compared with GO silage. Cows in the GC treatment had significantly greater (p&amp;lt; 0.05) total DMI (TDMI) compared with cows in the GO treatment. The daily CH4 emissions (in grams per day) were not affected by treatment; however, cows in the GC treatment had reduced (p&amp;lt; 0.05) CH4 yield (in grams per kilogram TDMI). Offering dairy cows GC silage over the pre-partum period resulted in greater DMI with reduced CH4 yield when compared with cows offered GO silage.

Updated method of estimating heat load for grazing dairy cattle

ABSTRACT Understanding heat stress in dairy cows is important for ensuring their welfare and productivity. While the Temperature Humidity Index is commonly used to determine heat stress conditions it does not consider outdoor factors (e.g. wind speed and solar radiation). To address this, the Grazing Heat Load Index (GHLI) which predicts respiration rate, an indicator of heat stress, was previously developed using data from the Waikato region in New Zealand. This study updated the GHLI using a weather data and animal heat stress indicators (e.g. respiration rate and drooling), collected from dairy herds in the Northland, Waikato, Canterbury, and Southland regions. A mixed-effects linear model, which included air temperature, solar radiation and wind speed as inputs was developed using data from these diverse locations. The updated model slightly outperformed the previous model on a validation dataset when predicting respiration rate. While air temperature remained the primary driver of respiration rate, solar radiation was an exacerbating factor, whereas wind exerted a mitigating effect. Challenges persist in characterising heat stress in conditions such as high wind speed. Non-linear modelling techniques could enhance the predictive capability of the GHLI model, thereby refining heat stress assessment in pasture-based dairy systems nationwide.

Temperament of the dairy cow relates to her maternal behaviour in a pasture-based extended suckling system

Cow-calf rearing is gaining interest in dairy systems as an alternative to calf separation soon after birth. One commonly articulated benefit of these ‘extended suckling’ systems is that they allow expression of highly motivated maternal behaviours. The quality of maternal expression is subject to natural variation, however, and could be influenced by the temperamental characteristics of the dam. This study assessed the relationship between cow temperamental characteristics and expression of maternal behaviours in a pasture-based extended suckling system. Sixteen dairy cows (Bos taurus) underwent social isolation, novel object and novel human tests at 4 months of pregnancy. A principal components analysis (PCA) was used to determine associations between cow responses in these tests. After parturition, the cows entered an extended suckling system (half-day contact) until calves were weaned. Cow-calf interactions at pasture were video recorded for 4 consecutive hours (∼09:00 AM – 1:00 PM) at weeks 3, 6 and 9 post-partum. These data were used to calculate a maternal behaviour score for cows by subtracting the frequency of “negative” maternal behaviours (i.e., agonistic behaviour delivered to own calf, rejecting own calf suckling attempt and rejecting attempted contact by own calf) from the frequency of “positive” maternal behaviours (i.e., nursing own calf, affiliative behaviour delivered to own calf and proximity to own calf). A Pearson correlation was then used to assess the relationship between factors scores and maternal scores. Three behavioural traits were identified from the PCA: boldness, anxiety and sociability. In general, cows delivered more affiliative behaviour to their calves than to other calves and to cows and nursed their own calf more than other calves. The maternal behaviour score varied (mean ± SD, 33 ± 13.4, minimum = 9, maximum = 49). Cows with higher loadings for boldness had a lower maternal behaviour score (p < 0.05). There was no correlation between maternal behaviour score and anxiety or sociability (p > 0.05). The lower maternal behaviour score of bold cows in this study might be influenced by their prioritisation of foraging and exploration over interactions with their calves. Despite the long-standing practice of calf separation soon after birth, the current study demonstrates that maternal abilities of pasture-based dairy dams persist. We conclude that cow temperamental characteristics are related to how the cows interacted with their calves.

Milk component ratios and their associations with energy balance indicators and serum calcium concentration in early-lactation spring-calving pasture-based dairy cows

Indirect assessment of metabolic status using milk samples provides a non-invasive and objective tool for cow-level health monitoring. Milk fat-to-protein ratio (FPR) has been commonly evaluated as an indirect measure for negative energy balance (EB) in confined dairy cows. However, milk component ratios have not been explored for their association with pasture-based cows' metabolic status. The objectives of this observational study were to 1) describe milk component ratios from 0 to 45 d postpartum, 2) evaluate the associations between milk component ratios [FPR, fat-to-lactose (FLR), protein-to-lactose (PLR)] and indicators of EB (serum β-hydroxybutyrate (BHB) concentration at 5-45 d postpartum and body condition score (BCS) change during the transition period), and 3) evaluate the associations between milk component ratios and serum Ca concentration 0-4 d postpartum in spring-calving dairy cows from pasture-based commercial farms. Milk component ratios were determined on samples collected before AM or PM milkings from 548 cows at 0-45 d postpartum (n = 970). Serum BHB and Ca determinations were performed in blood samples collected at the time of milk sample collection at 5-45 d postpartum (n = 918) and 0-4 d postpartum (n = 50), respectively; and BCS change was calculated using BCS assigned between 29 d prepartum and 45 d postpartum (n = 851). Cows' calving date, parity (1st, 2nd-3rd or ≥ 4th) and breed (Holstein-Friesian or dairy crossbred) information was obtained from the farm records. Data was analyzed by multiple linear regression. Average milk FPR, FLR and PLR were 0.70, 0.53 and 0.72, respectively. Milk FPR linearly increased while milk FLR linearly decreased postpartum both at a rate of 0.004 units per day; milk PLR decreased 0.05 units per day for the first 30 d postpartum and moderately increased afterward. Milk FPR and FLR were 0.71 and 0.52 units lower before AM than PM milking, respectively; while milk PLR was similar before AM and PM milking. Milk FPR and FLR were 0.07 to 0.10 units higher for 2nd-3rd compared with 1st and ≥ 4th parity cows. Milk PLR was 0.03 units greater for ≥ 4th compared with 2nd-3rd and 1st parity cows. Further, crossbred cows had 0.07, 0.08 and 0.03 higher milk FPR, FLR and PLR than Holstein-Friesian cows, respectively. Moderate to high P-values along with moderate to small estimated slopes and wide 95% confidence intervals were observed for the associations between milk component ratios and indicators of EB. A positive linear association was observed between milk FPR and serum Ca concentration within 4 d postpartum; milk FPR increased 0.31 units per each mmol/L increase in serum Ca concentration. Cows with low serum Ca concentration within 4 d postpartum had 0.27 units lower milk FPR compared with cows at or above the threshold (2.12 mmol/L), and tended to have 0.15 units lower milk FPR compared with cows at or above the threshold (2.00 mmol/L). In conclusion, further research is needed to reach conclusions on the association between milk component ratios determined before milking and EB indicators. The potential of milk FPR for monitoring blood Ca status warrants further investigation in early-lactation pasture-based dairy cows.

Predicting future adoption of early-stage innovations for smart farming: A case study investigating critical factors influencing use of smart feeder technology for potential delivery of methane inhibitors in pasture-grazed dairy systems

Globally, livestock farmers are challenged with reducing greenhouse gas emissions to mitigate climate change. A potential option for pasture-based dairy farmers involves including methane-inhibiting compounds in the diet. A novel approach to deliver these compounds with the required frequency and precision is via smart-feeders, an existing smart farming technology used to feed supplements automatically to animals in-paddock. For this innovation to be successful, however, it must integrate with farm systems and provide farmers with a positive value proposition. The aim of this study was to examine the farm system and technology factors influencing potential uptake of in-paddock smart technologies for delivering methane inhibitors in pasture-grazed systems. We utilized an adoption prediction tool (ADOPT) to model the adoption outcomes of smart-feeders as methane inhibitor delivery mechanisms on dairy farms, with input from industry experts and farmers via focus groups. The results indicated low adoption of smart-feeders in a pasture-based system context. This was further explored with a sensitivity analysis of seven critical ADOPT factors which were identified as influential through the farmer focus groups. We modelled the impact of the seven critical ADOPT factors for two smart-feeder concepts to evaluate their relative adoption potential. The adoption modelling showed that while factors such as technology cost and function were important, adoption would also be highly influenced by future regulation settings, innovation uncertainty, and the alignment with farmer values and worldviews about their farm system. This research highlighted that in-paddock delivery technology, and processes for its use on-farm, represents an early-stage innovation and therefore is vital that farmers and other stakeholders are involved in further development to ensure adoption factors are addressed.

A narrative review of factors affecting the welfare of dairy cows in larger Australasian pasture-based production systems

On the basis of current growth trajectories, pasture-based dairies of the future are likely to be bigger, have higher stocking rates and feed more concentrate to cows. This review uses the five-domains framework to consider risks to the welfare of dairy cows in these larger intensified pasture-based production systems. The factors considered in this review can be broadly categorised as (1) emerging welfare risks that can be managed, (2) emerging welfare risks that require research to be managed, or (3) persisting and/or exacerbated welfare risks. First, large herds could be subject to welfare risks associated with more stock per labour unit, longer milking times and longer distances walked to and from the dairy. To counter this, the time that cows in large herds spend off pasture can be reduced by splitting the herd into several more manageable groups, and animal-monitoring technologies can help identify health challenges with a reduced stockperson to animal ratio. Cow body condition and productivity can be maintained at high stocking rates by improving pasture production and feeding a higher proportion of concentrate. The risk of ruminal acidosis may then be reduced by appropriate transition feeding regimes and rumen buffers. Second, ensuring social stability and reducing competition may become difficult as herd sizes increase and feeding becomes more intensive. The resulting variability in feed intake, increased agonistic behaviour and social stress present emerging risks to cow welfare. Research is needed to better understand the social behaviour of cows in large intensive pasture-based herds, and how the design of the pre-milking area, the feeding pad and pasture feeding regimes (i.e. quantity and timing of pasture allocation) can improve accessibility for more vulnerable animals. Finally, intensive pasture-based dairies of the future will continue to face welfare challenges relating to lameness, mastitis and cull-cow management, whereas risks due to environmental exposure may be exacerbated by the removal of shelterbelts to facilitate irrigation. These require continued efforts in research (e.g. ways of incorporating shelter into intensive grazing systems), development (e.g. pathway to market for aged beef) and extension (e.g. improved record keeping and benchmarking of lameness and mastitis).

An exploration into the sleep of workers on block-calving, pasture-based dairy farms

The benefits of sufficient and high-quality sleep for people are well documented. Insufficient sleep increases the risk of accidents, injuries, and negative health implications for people. This is especially relevant for farmers because they work with large animals and machinery. Dairy farming often requires early start times and long days, particularly over the high-workload calving period in block-calving, pasture-based systems. However, there is little published data quantifying the sleep quantity and quality of farmers over this period. In this study, the sleep patterns of workers (n = 33) on 10 New Zealand dairy farms were measured for 90 d over the spring calving period using a sleep measuring device (Oura ring, Oura Health Ltd., Oulu, Finland). Total sleep time (TST) averaged 6 h 15 min, lower than the required 7 to 9 h for optimal wellbeing and cognitive functioning. The TST decreased over the calving period and was significantly correlated with both sleep start and wake times. Factors such as work start time, farm location, and role on farm influenced sleep quantity and quality. Further research is required to better understand sleep and its effect on dairy farmers, over both the calving period and the remaining months of the year.

Short communication: Association between prepartum subclinical magnesium imbalance and postpartum diseases in grazing dairy cows in Southern Chile.

This study aimed to evaluate the relationship between prepartum subclinical hypomagnesemia (pre-SHMg) and the occurrence of dystocia, metritis, clinical mastitis, lameness, and subclinical hypomagnesemia postpartum (post-SHMg) in pasture-based dairy cows. Also, the difference in means of prepartum magnesium (Mg) concentration by postpartum health events was evaluated. A total of 890 dairy cows from 32 commercial farms located in southern Chile were enrolled. Cows were examined twice, once between 30 and 3 days before and once between 3 and 30 days after calving. Blood samples were collected on both assessments, and cows were considered as having SHMg if serum total Mg < 0.65 mmol/L. On the postpartum visit, cows were evaluated for metritis and lameness. Information about clinical mastitis and dystocia was collected from on-farm records. Data were analyzed using multivariable mixed linear models and multivariable mixed logistic regression models. The overall prevalence of pre-SHMg was 9.9%, and its presence was associated with the occurrence of post-SHMg (odd ratio [OR] = 5.7; P < 0.0001) and metritis (OR = 3.1; P = 0.04). However, we did not detect an association between pre-SHMg and dystocia, clinical mastitis, or lameness after calving. Prepartum serum Mg concentrations were lower in cows that developed post-SHMg than those that did not (LSM ± SE = 0.75 ± 0.02 mmol/L vs. 0.83 ± 0.02 mmol/L; P < 0.0001). In conclusion, pre-SHMg was associated with a higher risk of post-SHMg and metritis in grazing dairy cows but not other postpartum health events.