Evaluating the immediate effects of hoof trimming on dairy goat hoof conformation and joint positions

Hoof overgrowth in commercial housed dairy goats is a major health and welfare concern; thus, it is important to better understand hoof trimming, a priority practice which addresses hoof growth. We evaluated the immediate effects of trimming on external conformation, internal joint positions, and hoof wall overgrowth of front and hind hooves. Eighty female goats were enrolled. Pre and post hoof trimming data were collected at 13, 17, 21 and 25 months of age. Overall, before trimming, a high percentage of hooves were scored as overgrown (77.8%). Trimming decreased the percentage of overgrown hooves (17.6%: P < 0.001) and other moderate/severe conformational issues: dipped heels (49.3% vs. 26.7; P < 0.001), misshaped claws (37.0% vs. 17.6%; P < 0.001), splayed claws (73.7% vs. 56.7%; P < 0.001). More hind than front hooves had dipped heels pre-trimming and (91.3% vs. 7.3%; P < 0.001) and post-trimming (52.8% vs. 0.6%; P < 0.001); over half of the hind heels were not restored to an upright position. A greater proportion of toe length was removed from the hind hooves compared to the front (0.50 vs. 0.43, P < 0.001), with the greatest proportion of hoof wall overgrowth removed from the hind hoof medial claw at the 13-month assessment (P < 0.001). Following trimming, distal interphalangeal joint angle decreased more in hind compared to front hooves (11.0° vs. 6.9°; P < 0.001); distal interphalangeal joint height decreased (0.21 cm, P < 0.001), and proximal interphalangeal joint, and heel, angles increased (7.76° and 8.93°, respectively; P < 0.001). Trimming did not restore conformation of all hooves when trimmed every 4 months, suggesting a need to investigate reasons for underlying poor conformation, including trimming frequency.

Evaluating the long-term conformation and hoof growth effects of starting hoof trimming at 5 months of age in New Zealand dairy goats

Hoof overgrowth is associated with poor conformation, an altered weight-bearing surface, and a reduction in the hoof's anatomic and functional integrity. As a result of housing systems that promote hoof overgrowth, hoof trimming is considered a priority in dairy goats. However, there are few data on the effects of the timing of first trimming on hoof conformation and growth rate. The aims of this study were (1) to evaluate the long-term effects of 2 different hoof trimming start times and (2) to investigate the pattern of hoof growth across the first 2 yr of life. Eighty 5-mo-old female Saanen-cross commercially housed dairy goats were allocated randomly to 1 of 2 treatments: (1) early trimmed (trimming beginning at 5 mo old; hooves were trimmed every 4 mo thereafter) and (2) late trimmed (trimming beginning at 13 mo old; hooves were trimmed every 4 mo thereafter). Using a combination of photographs and radiographs, hoof conformation, joint positions, and hoof wall length were assessed before the 13- and 25-mo trimming events. Hoof growth was assessed every 12 wk using caliper measurements. Overall, starting hoof trimming earlier had minor and inconsistent effects. However, detrimental changes in conformation and joint positions occurred between trimming events, particularly in the hind hooves, regardless of trimming treatment. At both assessments, there was a high percentage of overgrown toes and dipped heels, with the hind hooves being more affected compared with the front (overgrown toes at 13 mo, 97.1 vs. 79.1 ± 5.2%; overgrown toes at 25 mo, 91.7 vs. 56.3 ± 6.7%; dipped heels at 13 mo, 98.5 vs. 19.3 ± 5.0%; dipped heels at 25 mo, 88.3 vs. 4.9 ± 4.8%). In addition, at both assessments, the distal interphalangeal joint angle was greater in the hind hooves compared with the front (13 mo, 79.5 vs. 65.2 ± 1.7°; 25 mo, 79.0 vs. 66.7 ± 0.9°), whereas heel angles were less in the hind hooves compared with the front (13 mo, 41.8 vs. 57.1 ± 1.5°; 25 mo, 44.9 vs. 55.9 ± 1.1°). On average, the front hooves grew 4.39 mm/mo and the hind hooves grew 4.20 mm/mo. Early trimming did not have consistent effects on hoof growth rate. Importantly, our results suggest that trimming every 4 mo is not sufficient to prevent hoof overgrowth, the development of poor conformation, and detrimental changes in joint positions, particularly in the hind hooves. Furthermore, the detrimental changes may have masked any long-term treatment effects. Therefore, trimming frequency and age of first trimming should be considered when devising hoof care protocols for dairy goats housed in environments that do not offer opportunities for natural hoof wear.

979 FACTORS THAT INFLUENCE OLDER ADULTS’ PARTICIPATION IN PHYSICAL ACTIVITY: A SYSTEMATIC REVIEW OF QUALITATIVE STUDIES

Introduction

Despite the myriad advantages associated with physical activity (PA), older adults are often insufficiently active to maximise health benefits. Understanding factors that influence engagement in PA will support practitioners in providing well-designed interventions for older people. Our aim was to review the qualitative evidence exploring the factors affecting older adult’s engagement in PA.

Method

Four electronic databases were searched: CINAHL, Embase, MEDLINE and PsycINFO. Inclusion criteria were community-dwelling older adults (≥70 years), and studies including qualitative method. Exclusion criteria were studies examining a single disease group, individuals with cognitive impairment, care home residents, and PA interventions. The Critical Appraisal Skills Programme (CASP) checklist was used to assess methodological rigour. Framework synthesis using the COM-B model was applied to analyse data, and the GRADE-CERQual approach was used to assess confidence in findings. (PROSPERO: CRD42021160503).

Results

Twenty-one studies were included in the review. Participants (N = 3,955; mean age 78.9 years) included 64% female and 36% male older adults. Most studies were methodologically rigorous (17/21 scored ≥8 CASP). We identified 32 themes mapped against the COM-B framework (16 high confidence). Older adult’s perceived capability was influenced by their functional capacity, illness symptoms and perceived risk of injury from PA. PA was motivated by identifying as an ‘exerciser’, health gains and positive emotions (e.g. enjoyment), while negative sensations reduced motivation (e.g. pain). Opportunity was impacted by the weather, the environment ‘fit’, and the availability of social interaction during PA. Moreover, social opportunity was impacted by socio-cultural ageing stereotypes and discourses, influencing older adults’ PA through media outlets, social norms, and self-stigma.

Conclusion

The review found a complex web of interacting factors that influenced older people’s PA between the sub-domains of capability, motivation, and opportunity. Future initiatives to increase PA in older adults should focus on social influences, environmental barriers, and physical limitations.

POS0393 ASSOCIATION BETWEEN GENETICALLY PREDICTED EXPRESSION OF TPMT AND AZATHIOPRINE ADVERSE EVENTS IN PATIENTS WITH INFLAMMATORY CONDITIONS

Background

Azathioprine is a widely used immunosuppressant for the treatment of inflammatory conditions such as systemic lupus erythematosus (SLE), systemic vasculitis, dermatomyositis, and inflammatory bowel disease. However, its use is often limited by myelotoxicity. Variants in the gene encoding thiopurine-S-methyltransferase (TPMT), an enzyme in the metabolic pathway of azathioprine, increase the risk for myelotoxicity1. We know little about the relationship between the genetically predicted expression of TPMT and side effects of azathioprine.

Objectives

To examine whether genetically predicted expression of TPMT in liver tissue is associated with azathioprine adverse effects.

Methods

We assembled a retrospective cohort of new users taking azathioprine for inflammatory conditions at a tertiary care center. We performed genotyping with Illumina Infinium Expanded Multi-Ethnic Genotyping Array plus custom content data, and we then used Michigan Imputation servers for genetic imputation and PrediXcan models trained with GTEx/Genotype-Tissue Expression Project version 8 data to impute TPMT expression in liver tissue. We prespecified nine groups of phecodes (comprised of ICD9 and ICD10 codes) corresponding to known adverse effects of azathioprine. We then tested the association between the predicted expression of TPMT and these adverse events; for outcomes significant in the Wilcoxon ranksum tests (p<0.05), each case was reviewed in clinical records for confirmation. Finally, we grouped the predicted expression of TPMT in liver tissue into tertiles and conducted logistic regressions to assess the associations between predicted expression and side effects. We conducted a sensitivity analysis restricted to patients with EHR-reported White race.

Results

The cohort included 1034 patients (Table 1). Phecodes for 3 side effects—leukopenia (n=29), skin cancer (n=13), and rash (n=52)—were identified as associated with predicted TPMT expression in liver tissue. Of these, cases of side effects attributed to azathioprine were validated by chart review: leukopenia (96.6%; n=28), skin cancer (92.3%; n=12), and rash (9.6%; n=5) and used for analysis. When assessed by tertile of predicted TPMT expression, patients in the highest tertile had lower odds of having leukopenia (OR=0.35, 95%CI: 0.12-0.98, p=0.045) and a trend towards higher odds for skin cancer, but the number of cases was small (OR=3.56, 95%CI: 0.73-17.27, p=0.115). Confirmed cases of rash attributed to azathioprine were too few for meaningful analysis. We found similar results when restricted to patients with reported White race.

Table 1.

Characteristics of patients by TPMT expression

Lowest TertileMiddle TertileHighest TertileN=345N=345N=344Female sex, n (%)228 (66.1)244 (70.7)238 (69.2)EHR-reported White race, n (%)306 (88.7)293 (84.9)290 (84.3)Age, median [IQR]42 [29-58]43 [30-55]46 [30-56]Indication, n (%)Systemic lupus erythematosus38 (11.0)42 (12.2)38 (11.0)Inflammatory bowel disease191 (55.3)185 (53.6)190 (55.2)Other connective tissue disorder/autoimmune92 (26.7)96 (27.8)100 (29.1)Other24 (7.0)22 (6.4)16 (4.7)Verified leukopenia attributed to azathioprine, n (%)14 (4.1)9 (2.6)5 (1.5)Verified skin cancer attributed to azathioprine, n (%)2 (0.6)3 (0.9)7 (2.0)Verified rash attributed to azathioprine, n (%)2 (0.6)3 (0.9)0 (0)

Conclusion

This analysis suggests that PrediXcan may be useful for examining the association between gene expression and side effects of medications. Moreover, this approach successfully identified leukopenia as a side effect associated with predicted TPMT expression.

Acknowledgements

None to declare.

Disclosure of Interests

None declared.

POS1444 FLT1 AND EPHB2 ARE NOVEL GENETIC MARKERS ASSOCIATED WITH PANCREATITIS IN PATIENTS TAKING AZATHIOPRINE FOR IMMUNE-MEDIATED CONDITIONS: INTEGRATING GENOME- AND TRANSCRIPTOME-WIDE ASSOCIATION STUDIES

Background

Azathioprine (AZA) is a thiopurine immunosuppressant medication used to treat a variety of immune-mediated diseases. Unfortunately, its use is limited by adverse effects. Pancreatitis, a potentially severe, life-threatening side effect is independent of dose and necessitates AZA discontinuation given the high risk of recurrent pancreatitis with continued use or re-challenge. The mechanisms driving pancreatitis are unclear. While classic thiopurine-induced acute pancreatitis (TIAP) has been associated with HLA haplotypes, most patients taking AZA and presenting with pancreatitis do not fulfill the stringent criteria for TIAP.

Objectives

To identify genetic risk factors for pancreatitis in patients taking azathioprine for immune-mediated conditions.

Methods

Using a biobank linked to electronic health records (EHR) from a tertiary center, we identified new users of AZA. Patients were excluded if the primary indication for AZA was organ transplant or if there was a history of pancreatitis prior to AZA use. The analysis was restricted to patients with EHR-reported race as White due to insufficient case counts for the non-White group. We then identified patients with amylase or lipase values that exceeded twice the upper limit of normal (“>2x ULN”) or with ICD-9/ICD-10 codes for acute pancreatitis. Each record was manually reviewed to confirm the timing of AZA use in relation to laboratory derangements or ICD coding, as well as to further classify patients into three increasingly strict, but not exclusive categories: 1) pancreatic injury (amylase or lipase >2x ULN); 2) acute pancreatitis1, or 3) TIAP2. We completed genotyping with Illumina Infinium Expanded Multi-Ethnic Genotyping Array plus custom content data, employed Michigan Imputation servers for genetic imputation, and used PrediXcan (GTEx v8) to impute gene expression. We then conducted genome-wide association and transcriptome-wide association studies (GWAS, TWAS). Acknowledging the relatively small overall cohort, and possible imbalance of cases vs controls, we used the Firth logistic regression method, which is a penalized likelihood-based method.

Results

We studied 2127 AZA users (35.4% male; mean 44.5+/-17.2 years). The median AZA dose was 100mg/day (IQR: 50-125mg/day). Rheumatologic conditions (56.9%) and inflammatory bowel disease (40.4%) comprised the most common primary indications for AZA. Pancreatic injury, pancreatitis, and TIAP were diagnosed in 42 (2.0%), 16 (0.8%), and 9 (0.4%) patients, respectively. GWAS identified several significantly associated genes, many with overlapping TWAS findings in the pancreas and liver (Figure 1). From these, the two protein-encoding genes Fms Related Receptor Tyrosine Kinase-1 (FLT1) and Ephrin type-B receptor-2 (EPHB2) overlapped in two or more pancreatitis phenotypes in the TWAS and GWAS, respectively. EPHB2 was associated with a 8.6-fold (P=1.84 x 10-8) and a 31.4-fold (P=2.87x 10-8) higher likelihood of pancreatic injury and TIAP, respectively.

Figure 1.

Conclusion

FLT1—a gene that encodes a receptor tyrosine kinase and is a member of the vascular endothelial growth factor receptor (VEGFR) family—and EPHB2—a gene that encodes a member of the Eph receptor family, which is the largest subgroup of the receptor tyrosine kinase family—are novel genetic markers associated with pancreatitis in patients taking AZA. VEGF can potentiate inflammation and the pancreas microenvironment is known to promote VEGF expression, which has been linked to pancreatic cancer development; anti-VEGF treatments have been investigated both for mitigating inflammation and also anti-pancreatic cancer treatment. Future studies validating our findings in AZA-induced pancreatitis are warranted.

References

[1]Crockett et al. Gastroenterology (2018). 154(4):1096-1101.

[2]Heap et al. Nature Genetics (2014). 46:1131-1134

Disclosure of Interests

Shailja Shah Consultant of: ad hoc consultant for Phathom pharmaceuticals, Tyler Reese: None declared, Jacy Zanussi: None declared, Alyson Dickson: None declared, Laura Daniel: None declared, Ran Tao: None declared, Tyne Miller-Fleming: None declared, Peter Straub: None declared, Adriana Hung: None declared, Puran Nepal: None declared, Wei-Qi Wei: None declared, Elizabeth Phillips: None declared, Nancy Cox: None declared, Charles M. Stein: None declared, QiPeng Feng: None declared, Cecilia P. Chung: None declared

Landscape characteristics influence ranging behavior of Asian elephants at the human-wildlands interface in Myanmar

CONTEXT

Asian elephant numbers are declining across much of their range driven largely by serious threats from land use change resulting in habitat loss and fragmentation. Myanmar, holding critical range for the species, is undergoing major developments due to recent sociopolitical changes. To effectively manage and conserve the remaining populations of endangered elephants in the country, it is crucial to understand their ranging behavior.

OBJECTIVES

Our objectives were to (1) estimate the sizes of dry, wet, and annual ranges of wild elephants in Myanmar; and quantify the relationship between dry season (the period when human-elephant interactions are the most likely to occur) range size and configurations of agriculture and natural vegetation within the range, and (2) evaluate how percentage of agriculture within dry core range (50% AKDE range) of elephants relates to their daily distance traveled.

METHODS

We used autocorrelated kernel density estimator (AKDE) based on a continuous-time movement modeling (ctmm) framework to estimate dry season (26 ranges from 22 different individuals), wet season (12 ranges from 10 different individuals), and annual range sizes (8 individuals), and reported the 95%, 50% AKDE, and 95% Minimum Convex Polygon (MCP) range sizes. We assessed how landscape characteristics influenced range size based on a broad array of 48 landscape metrics characterizing aspects of vegetation, water, and human features and their juxtaposition in the study areas. To identify the most relevant landscape metrics and simplify our candidate set of informative metrics, we relied on exploratory factor analysis and Spearman's rank correlation coefficient. Based on this analysis we adopted a final set of metrics into our regression analysis. In a multiple regression framework, we developed candidate models to explain the variation in AKDE dry season range sizes based on the previously identified, salient metrics of landscape composition.

RESULTS

Elephant dry season ranges were highly variable averaging 792.0 km² and 184.2 km² for the 95% and 50% AKDE home ranges, respectively. We found both the shape and spatial configuration of agriculture and natural vegetation patches within an individual elephant's range play a significant role in determining the size of its range. We also found that elephants are moving more (larger energy expenditure) in ranges with higher percentages of agricultural area.

CONCLUSION

Our results provide baseline information on elephant spatial requirements and the factors affecting them in Myanmar. This information is important for advancing future land use planning that takes into account space-use requirements for elephants. Failing to do so may further endanger already declining elephant populations in Myanmar and across the species' range.

Incidence, causes and predictors of unplanned hospital readmission after percutaneous coronary intervention

Background

Unplanned hospital readmissions post-percutaneous coronary intervention (PCI) result in a significant burden to the healthcare system and adverse patient outcomes. Understanding factors associated with 30-day readmission rates may help to reduce this burden. Data linkage of clinical quality registry data with routinely collected administrative datasets may assist in overcoming resource constraints that limit collection of follow-up data but is currently under-utilised worldwide.

Objective

To determine the incidence of, and factors associated with unplanned hospital readmissions in the first 30 days following PCI.

Methods

We prospectively collected data on 28,488 patients undergoing PCI between January 2013 and December 2018, who were enrolled in a multi-centre PCI registry. Data linkage to government administrative datasets was used to determine whether patients had an unplanned readmission within 30 days of PCI, the number of admissions prior to PCI and primary reason for readmission (as recorded by the International Classification of Diseases, 10th revision, Australian modification (ICD-10-AM) diagnosis codes). Patients were then divided into 3 groups: those who had 1 or more unplanned readmissions for primarily cardiac issues, those who those who had 1 or more unplanned readmissions for primarily non-cardiac issues, and those who were not readmitted, and compared for baseline, procedural and in-hospital care characteristics.

Results

In total, 3,059 patients (10.7%) had an unplanned hospital readmission within 30 days of PCI, of which, 1,848 patients (60.4%) were readmitted for primarily cardiac diagnoses. Independent predictors of both 30-day cardiac and non-cardiac readmissions were female sex, having &gt;1 admission in the 12 months prior to PCI, acute coronary syndrome presentation, having any in-hospital complication and being discharged on an oral anticoagulant (all p&lt;0.05). A stepwise increase in readmission risk was observed with increasing number of admissions from 1 to &gt;4 admissions in the 12 months prior to PCI. Presentation with cardiogenic shock (p=0.04), having an unsuccessful PCI (p=0.02) and left ventricular systolic dysfunction (p=0.02) were independent predictors of cardiac readmissions but not non-cardiac readmissions. Conversely, age &gt;60 years (p&lt;0.001) and history of diabetes mellitus (p=0.02) were found to be independent predictors of non-cardiac readmissions only.

Conclusion

Thirty-day unplanned hospital readmissions after PCI pose a significant burden to the health system. Most readmissions are primarily due to cardiac diagnoses. The most important predictive factor for both cardiac and non-cardiac readmissions appears to be the number of hospital admissions in the 12 months prior to PCI. This is valuable information for health administrators as treatment and discharge policies, and outpatient follow-up timetables may need to be tailored to patients at high risk for readmission following PCI.

Causes of readmission post-PCI

Funding Acknowledgement

Type of funding source: None

P2654Impact of cultural and linguistic diversity on ischaemic time and clinical outcomes in patients undergoing percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI)

Background

Healthcare providers worldwide increasingly must face the challenge of providing care to culturally and linguistically diverse patients who may have limited proficiency in the primary working language of the country they are in. This language discordance may lead to delayed treatment and worse outcomes. The impact of limited English proficiency (LEP), in a predominantly English-speaking country like Australia, on time to reperfusion and outcomes following PCI for STEMI has not been previously studied.

Objective

Among patients undergoing PCI for STEMI, to compare baseline and procedural characteristics, time to reperfusion, and 30-day clinical outcomes in patients with LEP, compared to their English-proficient counterparts.

Method

We prospectively collected data on 7,721 patients undergoing PCI for STEMI between January 2013 and December 2017 who were enrolled in the state-wide multi-centre Victorian Cardiac Outcomes Registry. Data linkage to Department of Health administrative datasets was used to identify patients' primary spoken language. Patients who identified a language other than English as their primary spoken language were classified as having LEP. Patients' postcodes were used to identify socioeconomic status through Australian Government census data. The primary endpoint was 30-day major adverse cardiovascular events (MACE)

Results

Of the 7,721 patients included, 568 (7.4%) had LEP. Patients with LEP were more likely to be older, female, diabetic, have lower socioeconomic status and have severe renal impairment (all p<0.02). They were also more likely to present to a non-PCI capable hospital (p<0.001). Among primary PCI patients (n=5,385), symptom-to-balloon time was longer in the LEP group (237 [IQR 158–429] vs. 195 [IQR 141–326] minutes, p<0.001), driven mostly by longer symptom-to-door times (STDT) (150 [IQR 90–276] vs. 114 [IQR 75–215] minutes, p<0.001). LEP patients were also less likely to have a STDT≥120 minutes (48.8% vs. 41.7%, p-0.004). Patients with LEP had higher 30-day mortality (8.8% vs. 6.5%, p=0.04) and MACE (11.8 vs. 9.1%, p=0.04). They were also more likely to have severe left ventricular (LV) dysfunction post-STEMI (11.2% vs. 8.4%, p=0.003) and heart failure readmissions within 30 days of PCI (5.2% vs. 2.0%, p<0.001). On multivariate analysis, LEP was not an independent predictor of 30-day MACE (OR 1.27, 95% CI 0.82–1.95), but was an independent predictor of STDT≥120 minutes (OR 1.24, 95% CI 1.02–1.52).

Comparison of reperfusion times

Conclusion

Limited English-proficient patients with STEMI undergoing PCI tend to present later than their English-proficient counterparts and are more likely to have severe LV dysfunction and heart failure readmissions. LEP is an independent predictor of prolonged STDT but not 30-day MACE. This suggests that more effort needs to be placed in providing education in different languages to culturally and linguistically diverse patients, to encourage early presentation in the setting of STEMI.

Farmed red deer home range, habitat use and daily movement patterns in a Southland, New Zealand, tussock grassland over calving and lactation

Considerable expansion of red deer farming has occurred in the South Island high country of New Zealand. On these farms, breeding hinds are usually continuously grazed (set-stocked) at low population densities in large highly modified native-tussock grassland paddocks during their calving and lactation seasons. The present study determined how these hinds use the tussock grassland over this critical period, identifying the most essential resources for them and also some potential long-term consequences of their behaviour on the grassland ecosystem. This was achieved by tracking nine GPS-collared hinds over 2 years on a high-country deer farm in Te Anau, Southland, New Zealand. The home ranges of the GPS-tracked hinds varied widely, occupying between 15% and 52% of the total paddock area. Vegetation dominated by naturalised exotic pasture species covered the greatest proportion (&gt;60%) of eight of nine hind home ranges. In contrast, tussock-dominant vegetation coverage was far more variable (0.4–46%), with several indicators suggesting that this vegetation type was used as a substitute for pasture areas under high intra-specific competition among the deer. Both pasture- and tussock-dominant vegetation was used in proportion to its availability. In contrast, shrub-dominated vegetation was used less than its proportional availability, indicating that it was not being put under as much foraging or grazing pressure. This has implications for the further ingression of this vegetation type over time. There was also clear evidence that certain paddock topography was being favoured by the hinds, namely steeper and higher-altitude areas of a paddock. On the basis of these findings, some potential methods for aiding in the management of these extensive tussock grassland paddocks under deer grazing are suggested.

Attendance at child psychiatric clinics

A study of 41 families who failed to attend their first appointment at a child psychiatric clinic is described. The study was prospective over a period of one year and the families were interviewed personally; 14.9% failed their first appointment. Improvement of the child's symptoms during the waiting period, anxiety about seeing a psychiatrist/social worker, financial difficulties and the invitation to the family to attend were common reasons given for non-attendance. Another important factor was that families were ill-prepared by the referrers.

Assessing the Yield and Load of Contaminants with Stream Order: Would Policy Requiring Livestock to Be Fenced Out of High-Order Streams Decrease Catchment Contaminant Loads?

Catchment contaminant loads vary with stream order as catchment characteristics influence inputs and in-stream processing. However, the relative influence and policy significance of these characteristics across a number of contaminants and at a national scale is unclear. We modeled the significance of catchment characteristics (e.g., climate, topography, geology, land cover), as captured by a national-scale River Environment Classification (REC) system, and stream order in the estimation of contaminant yields. We used this model to test if potential regulation in New Zealand requiring livestock to be fenced off from large (high)-order streams would substantially decrease catchment contaminant loads. Concentration and flow data for 1998 to 2009 were used to calculate catchment load and yields of nitrogen (N) and phosphorus (P) species, suspended sediment, and at 728 water quality monitoring sites. On average, the yields of all contaminants increased with increasing stream order in catchments dominated by agriculture (generally lowland and pastoral REC land cover classes). Loads from low-order small streams (<1 m wide, 30 cm deep, and in flat catchments dominated by pasture) exempt from potential fencing regulations accounted for an average of 77% of the national load (varying from 73% for total N to 84% for dissolved reactive P). This means that to substantially reduce contaminant losses, other mitigations should be investigated in small streams, particularly where fencing of larger streams has low efficacy.