Journal of New Zealand Grasslands

Fuelled by Science and Tempered by Experience

Laurie Copland — 2024-10-31

Graham Kerr, in his Address, said he “joined the (NZGA) Executive, to support science and objective thinking.” He also said “science is under fire, as never before. It is misquoted, misused and misunderstood.” Over my 45 years as a farmer, I’ve witnessed movements in farming that are supposedly better than conventional farming. Permaculture, Organic,
Biodynamic and more recently Regenerative. Whether these are better depends on definitions. For me, I’m a conventional farmer, which by my definition means using science.

55 Years in Agribusiness – challenge, opportunity and change

Robert Cottrell — 2024-10-31

It is indeed an honour and privilege to be asked to deliver this year’s Sir Bruce Levy oration. While I was not an evangelist of Sir Bruce Levy’s writings, as students of the 1960’s we were well aware of the significant influence his work played in shaping the grassland systems of New Zealand farming. By the time we graduated in the 1970’s Sir Bruce’s ideas and Grassland DSIR were well advanced in breeding grasses and legumes that fitted with intensive grazing systems across the country. His legacy still prevails today in our modern grassland systems.

My topic for today is “55 years in Agribusiness – challenge, opportunity and change“. It poses a few anecdotes of my journey and experiences, challenges and learnings through the period of the 1970’s to 2023. I will also touch on some observations within the Maori agriculture sector during this time and the challenges and opportunities that lay ahead. And finish with some thoughts for the future.

Challenges and opportunities impacting New Zealand’s economic foundation – pastoral agriculture

John Caradus — 2024-10-31

New Zealand is unique amongst OECD countries in its reliance on pastoral agriculture for generating export dollars that underpins its economy. However, this biologically based production system is open to an unprecedented level of challenge which includes maintaining a high level of productivity to ensure international competitiveness, the impact of regulations and compliance, a social license to operate, the development and uptake of new technologies, competition from non-animal sourced foods, ensuring an adequate and well directed level of R&D investment, acceptable impacts on the environment and conversely having mitigation strategies to ensure adaptation to changes in climate, farming continuity through supply of adequate skilled labour, land use change, biosecurity breaches, and enabling added value opportunities to be developed. The aim here is to review these challenges and identify options for alleviating, managing or mitigating them.

Where to now for forage productivity in dairying?

Bruce Thorrold — 2024-10-31

There is no serious dispute that farmer profitability and national milk production are underpinned by grazed pasture. DairyNZ data shows that the amount of homegrown pasture and crop consumed is the best predictor of profit per hectare (Macdonald and Roche 2023). National feed consumption data shows that approximately 75% of dairy cattle diets are from directly grazed forages (DairyNZ Economic Survey). The importance of high genetic merit cows and management skill in turning the inherent competitive advantage of grazed pasture into profit and production are also well documented (e.g. Macdonald and Roche 2023).

Effect of modern red clover & nitrogen fertiliser on yield, quality and botanical composition of a hybrid ryegrass sward

Fraser Harrison — 2024-11-15

The advantages to pasture quality and quantity using red clover in New Zealand farm systems is becoming more recognised. The performance of tetraploid hybrid ryegrass, with and without red clover, and with and without nitrogen fertiliser (276 kg N/ha/annum) was compared with a pure red clover stand in three replicated plot experiments, established in 2019 in the Manawatu, Canterbury and Southland provinces of New Zealand. This paper presents the combined multi-site analysis of treatment, season, and year, comparing dry matter (DM) production, composition and feed quality under a cutting regime for 3 years. Adding both red clover and fertiliser to hybrid ryegrass increased total dry matter production, metabolizable energy and crude protein concentration of the pasture. Hybrid ryegrass without fertiliser yielded 24,660 kg DM/ha over three years, while the addition of red clover or nitrogen fertiliser separately increased total yield (p<0.001) by 18,180 and 14,850 kg DM/ha respectively. When combined, yield was increased (p<0.001) by 23,340 kg DM/ha. Fertiliser use and season had a significant effect (p<0.001) on the red clover percentage of the pasture. While fertiliser
use decreased the percentage contribution of the clover to total yield, total yield was increased from additional grass growth particularly in late spring and summer and additional red clover growth in summer. The addition of red clover in pasture significantly increased overall and seasonal production regardless of fertiliser practice. Maintaining fertiliser contributed to a balanced feed curve with high total production and benefiting the autumn-winter production phase.

Spring growth of lucerne (Medicago sativa L.) after different times of winter defoliation

Lauren Jones — 2024-10-31

The aim of this work was to determine if autumn/winter defoliation affected the time of lucerne (Medicago sativa L.) stem extension in spring. Two experiments were established at the Field Research Centre, Lincoln University. Experiment 1 was established on 1 June 2022 using an existing two year old stand of “Force 4” lucerne. There were four canopy defoliation dates (1 June, 3 July, 17 July and 1 August). Experiment 2 repeated the treatments on the same paddock in the following year on eight defoliation dates (1 May, 15 May, 1 June, 15 June, 3 July, 17 July, 1 August and 15 August). In both experiments, five stems were marked in each plot and stem height was measured weekly. The start of stem extension was unaffected by canopy defoliation date in both 2022 (P = 0.20) and 2023 (P = 0.17). Initiation of stem extension was triggered by a base photoperiod of 11.1 ± 0.2 h. This meant the thermal time accumulated from final defoliation to the start of stem extension differed among treatments. These results suggest the time of autumn/winter defoliation (the winter clean-up graze) will not affect the time of the first spring grazing, provided the developing basal buds are not removed. All stands reached 150 mm height by mid-September and produced 3.0 t/ha of dry matter by the end of September. This suggests, grazing of the first paddock at Lincoln should commence in the first week of September to create a staggered start to rotational grazing that can maximise lucerne yield and quality for animal production.

Survival of white clover rhizobium isolate S11N9 in different delivery systems: assessment of potential for commercialisation

Shengjing Shi — 2024-10-31

New Zealand pastoral farmers benefit from N₂ fixed by the white clover-rhizobium symbiosis, but rhizobia isolates vary widely in their N-fixation ability. Rhizobium leguminosarum S11N9, isolated in NZ, outperforms the current commercial isolate TA1 in laboratory, glasshouse, and field trials. This study investigated production and shelf-life of S11N9 to establish its feasibility as a potential new rhizobium inoculant for white clover. Freeze dried and peat inoculants were prepared for both the S11N9 and TA1 rhizobia. s. Peat inoculants were subsequently formulated into granules and seed coatings using AgResearch technologies. Both isolates produced similar fermentation yields. S11N9 stored as freeze-dried powder at 4 ^oC survived longer than TA1 (12 vs. 10 months, respectively). Similarly, S11N9 peat inoculant had a longer shelf-life than TA1 when stored at 4 °C (44.7 vs. 21.7 months, respectively) and 20 °C (17.2 vs 9.1 months, respectively). Seeds coated with S11N9 had higher initial loadings than TA1 (10⁷ vs 10⁶ rhizobia/g seeds, respectively) but both declined on seeds stored at 20 °C at a similar rate. Both isolates were stable in peat granules for two months at 20 °C but TA1 dropped below target specifications after three months. Results suggest that isolate S11N9 is a promising alternative to TA1 and has high potential to be developed as a commercial inoculant for white clover.

Clover and grass foliar nutrient responses to phosphorus and molybdenum fertilisers, and herbicide application on a summer dry hill pasture

Sonya Olykan — 2024-10-31

Pastures on the Port Hills, Canterbury, are typically grass-dominant growing on low Olsen P soils and enduring summer-dry conditions. Subterranean (sub) clover is the preferred legume on steeper dryland hill slopes, but clovers struggle to compete with resident grasses for soil moisture and nutrients. Nutrient concentrations in sub clover and grass foliage were sampled each spring, from 2021 to 2023, in an experiment with factorial combinations of phosphorous (0 or 60 kg P/ha, -P or +P), sulphur (0 or 50 kg S/ha,
-S or +S), and molybdenum (0 or 0.06 kg Mo/ha, -Mo or +Mo) fertilisers, and plus or minus autumn grass-supressing herbicide. In the unfertilised controls, sub clover had higher foliar concentrations of N, Ca, Mg, B, Cu and Zn than the grasses which had higher concentrations of P, K, S and Mo, which are the nutrients commonly applied in fertilisers to support clover growth. Applying P increased foliar P from 0.16 to 0.27% in sub clover and 0.21 to 0.34% in grass in 2023. Sub clover and grass foliar S concentrations were
mainly affected by sampling year. The +Mo treatment only elevated sub clover Mo in 2022 from 0.05 to 0.11 mg/kg. However, each year +Mo increased sub clover foliar N% from 4.1 to 4.5% in 2021, 3.7 to 4.0% in 2022, and 4.3 to 4.8% in 2023. Grass foliar Mo was
elevated by +Mo from ~0.45 to 1.42 mg/kg in 2021 but then concentrations declined to 0.99 and 0.67 mg/kg in 2022 and 2023 respectively. Grass Mo values were, on average, 10 times higher than in the sub clover. Grass N% was increased where herbicide was applied, increasing from 2.6 to 3.0% in 2022 and 3.6 to 3.9% in 2023. In 2023, the +P+S+Mo fertiliser treatment increased N, P, S, Mg and B in fertilised sub clover compared with control. To maximise clover nutrition and growth on this low P site the regular addition of
superphosphate, with molybdenum every four years, is recommended in conjunction with grass control in
autumn.

Subterranean clover growth responded to grass suppression, phosphorus and molybdenum fertilisers in a summer dry hill environment

Sonya Olykan — 2024-10-31

Pastures on the north-facing slopes of the Port Hills, Canterbury, are summer-dry, grass dominant, and have low soil phosphorous and sulphur fertility. The aim of this experiment was to improve the establishment of oversown subterranean (sub) clover by the addition of fertilizer and grass-supressing herbicide. Treatments were a factorial combination of phosphorous (0 or 60 kg P/ha, -P or +P), sulphur (0 or 50 kg S/ha, -S or +S), and molybdenum (0 or 0.06 kg Mo/ha, -Mo or +Mo), with or without autumn herbicide (plus or minus, +H or -H). Fertilisers were applied in 2021, with P and S reapplied in 2023, and herbicide applied in 2022 and 2023. Pasture yields were measured annually from 2021 to 2023.

Measurements in 2021 found no fertiliser effect on total pasture yield of 3650±83 kg DM/ha that included 770±43 kg of sub clover. In 2022, P addition increased total pasture yield from 2900 to 3270 kg DM/ha. Herbicide application doubled the sub clover yield from 310 to 645 kg DM/ha and reduced grass from 1650 to 1410 kg DM/ha. In 2023, the herbicide application did not affect the total accumulated pasture yield (10180±160 kg DM/ha) but increased sub clover content from 10 to 25% and reduced the grasses from 63 to 47%, with about 4% white clover. Where herbicide was applied without fertiliser (+H), total clover yield increased from 1460 to 2930 kg DM/ha. The application of P and Mo, (i.e., +H+P+Mo treatment) increased it further to 4010 kg DM/ha. There was no yield response to +S or +Mo unless added with P.

Applying herbicide or phosphorous increased total metabolisable energy from 38.5 to 42.6 GJ ME/ha and crude protein from 500 to 595 kg/ha in pastures sampled in November 2023. The treatment combination providing the highest feed quality values was +H+P+Mo.

These results suggest that to optimise sub clover content of pastures on the Port Hills competing grasses must be controlled initially, followed by P fertiliser if soil tests indicate it is required along with molybdenum.

Influence of diverse pasture species and reduced nitrogen fertiliser inputs on soil health on four irrigated Canterbury dairy pastures

Nicole L Schon — 2024-10-31

Maintaining and improving the health of pastoral soils is important to enable the provision of ecosystem services for sustainable production. We investigate the impacts of increasing pasture species diversity and reducing nitrogen (N) fertiliser inputs on pasture productivity and the flow on effects for soil health on four irrigated dairy farms in Canterbury. The soils had generally good health prior to pastures being resown. During the establishment of both simple and diverse pastures there was a decline in Olsen P, soil organic carbon (C), total N and potentially available N to below target levels. In the year following pasture establishment there was no difference in herbage accumulation between the simple and more diverse pastures under irrigation. For both simple and diverse pastures, grass species contributed approximately 50%, legumes 15%, and herbs 20% of the total dry matter harvested. Although there was a reduction in pasture growth as N fertiliser inputs were reduced, legume content did not decline significantly and differences in soil health were not observed at this stage. Despite the farms being intensive dairy systems, the data suggests good soil health prior to pasture establishment. Hence maintaining soil health as well as its restoration following disturbance present opportunities for these farms.

Investigating the impact of treading damage on the plantain (Plantago lanceolata L.) content and performance of a plantain/ perennial ryegrass (Lolium perenne L.) pasture over two years.

Sam Wilson — 2024-10-31

There is industry concern over the difficulty of maintaining a satisfactory plantain (Plantago lanceolata L.) content within plantain/ perennial ryegrass (Lolium perenne L.) dairy pastures. One cause of the sharp decline in plantain content may be treading damage from grazing dairy cows during early spring. In an experiment at Massey University, Palmerston North, the impact of cow treading damage on the plantain content of a plantain/perennial ryegrass pasture was investigated over two production years. Measurements of pasture yield, canopy development, botanical composition and growing point density captured the response of the pasture, to the treading damage. Pasture growth was reduced by 50% and 75% following cow treading damage during the early spring periods of year one (2022) and two (2023), respectively (P<0.05). Plantain content and shoot density tended to be lower in damaged plots during early spring, before recovering throughout summer, although this effect was more pronounced during year one. These results re-iterate the importance of avoiding treading damage to ensure optimal plantain content and pasture production throughout spring. The reduction in plantain content in all plots during the second year of the experiment reflected industry observations, suggesting that treading damage likely provides only a part of the explanation for declines in plantain content observed on-farm. Alternative causes, and potential mitigations of the decline in plantain content within perennial ryegrass-based dairy pastures, are discussed.

Regenerative management effects on pasture production: initial data from a dryland farmlet experiment

Kaitlin Watson — 2024-10-31

Data comparing pasture production in sheep farmlets subject to regenerative or conventional management and high or low soil fertility were collected in the first 1.5 years of a dryland experiment at Lincoln University. The data were retrieved from eight replicates of a 20-replicate design. In those replicates, the regenerative management combined diverse pastures and rotational grazing at high stock densities and frequent shifts. The conventional management combined lucerne pastures rotationally grazed at lower densities and frequencies. The high and low fertility treatments received 64 and 4 kg/ha P fertiliser respectively before sowing in December 2021. For July 2022–June 2023, regenerative management resulted in greater average pasture mass (2.6 versus 1.7 t DM/ha) of different botanical composition (5% prairie grass, 19% tall fescue and meadow fescue, 21% lucerne, 7% chicory, 7% plantain, a total of 10% cocksfoot, timothy, phalaris, white, red and sub clovers, 4% weed and 27% dead versus 70% lucerne, 11% weed and 19% dead) but lower annual pasture yield (8.7 versus 11.5 t DM/ha). Reducing P neither decreased pasture and legume yields nor increased weed. The two managements did not differ in their ability to produce pasture with less P. These initial results provide quantified evidence for farmers making decisions about regenerative agriculture.

Pasture formulation for optimised yield and weed suppression under sheep grazing and irrigation in Canterbury

Arulmageswaran Shampasivam — 2024-10-31

Farmers need evidence to make informed decisions about which species to sow when renewing a pasture. This study aimed to formulate a pasture from a diverse pool of six species. At Lincoln University, 69 monocultures and mixtures varying widely in sown number and proportions of perennial ryegrass, cocksfoot, plantain, white clover, red clover and subterranean clover were examined under sheep grazing and irrigation for 4 years. On average annual total dry matter (DM) yield increased and weed DM yield decreased with increases in number of species, but species’ proportions determined the optimal pasture that maximised yield and weed suppression. For example, on average six-species pastures had 1.6 t/ha more total yield and 1.8 t/ha less weed yield than twospecies
pastures (12.1 and 3.1 t/ha) in Year 1. However, several pastures of equal number of species had both above-average total and below-average weed yields in each year, emphasising the importance of species identity. A diversity-interaction model predicted that sown proportions of 50% ryegrass and 25% each of white and red clovers maximised annual yield and weed suppression (14.1 and 0.3 t/ha). These seed ratios were equivalent to 9.7, 1.3 and 9.0 kg/ha respectively for a total sowing rate of 20 kg/ha.

Multi-year performance of white clover oversown into eastern North Island hill country

Michael Dodd — 2024-10-31

Animal performance on summer-dry North Island hill country pastures is limited by soil fertility and the challenge of establishing and retaining a strong legume base in swards on steeper slopes. However, this can be overcome by 1. selecting legume species adapted to the various slope, aspect and soil type combinations; and 2. following well-recognised establishment and management techniques developed in the 1980s. We broadcast white clover in two large southerly aspect paddocks on Tangihanga Station, Gisborne, in the autumn of 2019. Establishment methods involved resident pasture control by hard grazing and selective herbicide to supress dominant low-fertility grasses, broadcasting at high sowing rates and trampling of seed with sheep. We followed white clover persistence and animal performance over the subsequent 5 seasons of rotational cattle grazing with heifers and steers, in comparison with adjacent unsown paddocks. The cost of establishment was c. $220/ha. White clover abundance remained high throughout the 5 years, between 25-40% of cover, compared with 7-17% in unsown paddocks. This increase in clover content of the pastures translated into both increased stocking rates and per head growth rates, with overall annual LWG increasing by 67-169% depending on season. The investment was paid back within the first year.

Regenerative grazing practices and the sustainability of a beef production system in New Zealand

Gerald Cosgrove — 2024-10-31

‘Regenerative’ grazing practices are being promoted by some pastoral farmers. A study commenced in 2022 is testing if maintaining higher pre- and post-grazing cover, longer intervals between grazing and higher stocking intensity, but shorter duration of grazing, will improve nutrient use efficiency (phosphorus (P), nitrogen (N)) and carbon (C) sequestration in the soil, while maintaining or increasing pasture and animal productivity. This ‘Adaptive’ grazing practice was compared against a ‘Control’, both under rotational grazing by cattle. This paper reports baseline soil physical and chemical measurements collected in autumn and autumn and spring in 2022, and pre- and post-grazing herbage mass measured over two years through to autumn 2024. Soil baseline data indicate good nutrient fertility (Olsen-P, pH, exchangeable cations), physical condition, biological and microbial biomass and organic matter levels. The instantaneous stocking loading at grazing, a key indicator of the contrast between grazing treatments, was 15,500 and 150,400 kg liveweight/ha for the Control and Adaptive grazing treatment, respectively. The high, pre-grazing target mass (3500 – 4000 kg DM/ha) was achieved at only two of the 15 grazing cycles, with the overall mean of 2850 kg DM/ha less than target. Mean residual grazing mass was 2150 kg DM/ha. There is no evidence after two years that grazing treatments affected on pasture productivity. Changes in these soil and pasture parameters over time will be assessed against the baseline measures reported here.

The environmental performance of a pasture and baleage wintering system on a poorly drained soil in southern New Zealand

Priscilla Simon — 2024-10-31

Concern about environmental and animal welfare outcomes associated with crop-based wintering has prompted interest in the potential feasibility of pasture based approaches as alternative wintering methods. This interest is especially relevant to southern regions of New Zealand where forage crops are prevalent and soil quality can deteriorate during wet winter conditions. We compared changes in soil condition and nitrogen (N) leaching losses from treatments where mature dairy cows were winter-grazed on either fresh (annual) pasture and baleage or brassica crops as the main sources of dietary feed. These responses were measured from
large spatially randomized and hydrologically-isolated mole-pipe drained plots over a three year monitoring period. Considerable soil treading damage was incurred under both wintering treatments. Recovery of pasture in the pasture plots was accordingly slow, particularly in 2021 when soil conditions at the time of plot grazing were relatively wet: four months after grazing, about 30% of plot area remained bare, requiring resowing. Pasture recoveries in 2022 and 2023 were faster, with less than 20% bare ground present 3 months after winter grazing. There were no significant differences in N losses in drainage from the treatments in 2021 and 2022. Significantly more N was leached from the pasture-baleage than the crop treatment in 2023, most likely a consequence of a late autumn grazing that was required to manage pasture quality. Pasture-baleage wintering did not reduce N leaching compared to
wintering on crop for this soil type. Whilst measures of soil quality were better under the pasture-based than the crop-based wintering treatment, overall soil condition was assessed as poor for both treatments. A shift from crop to pasture-baleage wintering would appear to offer only modest advantages to soil and water quality when deployed on structurally-vulnerable soils. Other measures to help minimise soil treading damage, such as providing loafing surfaces or using standoff pads during very wet conditions, are likely needed to improve the performance of this pasture-based system on such vulnerable soil types.

Can additives or controlled release coating improve the nitrogen use efficiency of urea fertiliser

Racheal H. Bryant — 2024-10-31

A plot trial was undertaken to determine whether tactical use of nitrogen (N) fertiliser applied with or without coating or biostimulant improved herbage yield and N use efficiency. A randomised complete block design was used to compare no fertiliser (CON), frequent low rates of urea (FL), infrequent moderate rates of urea (IM), IM with controlled release (IM+CR), IM with Progibb (IM+PG), IM with Agrisea (IM+AS), or IM with N-Boost (IM+NB) on irrigated, grazed perennial ryegrass and white clover dairy pastures in Canterbury. The total annual N applied in all fertilised treatments was 190 kg N/ha. The use of fertiliser increased annual herbage yield (16.9±0.44 vs 14.5 t DM/ha/y; P<0.05). Combining urea with a coating or biostimulant altered the distribution of pasture growth, but did not affect net annual production or herbage quality. Due to the lack of response and greater application costs with liquid versus granule products, these results highlight the need to consider expected responses to different fertiliser regimes when adopting practices to achieve economic benefits and N efficiency.

Nitrogen leaching losses from pasture and winter forage crops in the West Matukituki Valley

Chris Smith — 2024-10-31

In 2013 the Otago Regional Council (ORC) entered mediation with local farmers on changes to their Water Plan, Plan Change 6A, which sought to apply nitrogen load limits within the catchments of Lake Wanaka and Lake Hawea for all farm systems. There was little information available on nitrogen leaching losses in the high rainfall environments (c 2500 mm pa) of the South Island's high country. Agreement after mediation with the ORC and local farmers required a research project to examine differences between measured losses and outputs from OVERSEER^® at a paddock and farm scale. To address this knowledge gap, a series of monitoring sites were set up in November 2014 in the West Matukituki Valley, west of Lake Wanaka. Porous soil solution samplers were installed to a depth of 50 cm in (i) a sheep- and cattle-grazed pasture, (ii) a cattle-grazed winter forage crop, and (iii) a native bush site. Results for 2015 showed that rainfall totalled 2240 mm, with calculated drainage estimated at 1330 mm. The total fluxes of dissolved N from the crop and pasture sites during the 12 months from June 2015 were 157 and 43 kg N/ha, respectively. Dissolved organic N (DON) made an unexpectedly large contribution to these fluxes, accounting for 20 and 67% of the total fluxes of dissolved N in drainage from the crop and pasture sites, respectively. Gaining a better understanding of the bioavailability of dissolved forms of organic N in leachate would help determine the risks that these forms of nutrients pose to water quality, and if they should be incorporated into models such as Overseer which do not account for DON. The project’s initial findings enabled an informed discussion on the use of modelled results from Overseer for the mitigation of N loss at a farm scale in the lakes’ catchments. It also focussed farmers’ attention on management of the nitrogen leaky parts of their farm systems, especially winter crops.

Adequacy of equations used to calculate urinary nitrogen contribution to total nitrogen excreted by ruminants

Ronaldo Eduardo Vibart — 2024-10-31

Nitrogen (N) concentration in the diet is the best sole predictor of the contribution of urinary N to total N in excreta. A large database was compiled containing feed and excreta variables from dairy cattle, beef cattle, sheep and deer, to evaluate the predictive ability of five linear models and four non-linear models to calculate the contribution of urinary N to total N in excreta. Species-specific linear models for beef cattle and sheep did not result in better predictions than those obtained from a generic linear model developed for all ruminant species. The predictive ability of a non-linear dairy cattle model was noticeably better than that of a linear model. The poor performance of a linear model along with a smaller number of observations from deer studies points to the merit of the construction of a new deer-specific model. This study provides support for the robustness of N partitioning towards urinary N in the animal sub-model of OverseerFM™ for a comprehensive range of diets with varying N concentration for beef cattle and sheep. In the future, the use of more sophisticated modelling approaches that involve partitioning of data for model development and evaluation may be required.

Bulk milk urea as an indicator of herd dietary nitrogen surplus and nitrogen use efficiency on Canterbury dairy farms.

Roshean Woods — 2024-10-31

Managing herd dietary nitrogen surplus (DNS) remains a core challenge on pasture-based dairy farms to reduce the risk of nitrogen loss to the environment. To manage their herd’s DNS, farmers need readily available, practical indicators. In an observational longitudinal study of five Canterbury dairy farms over five seasons (2014/15 to 2018/19), we explored the usefulness of bulk milk urea concentration (BMU; mg/dL) and bulk milk urea nitrogen to milk protein nitrogen ratio (BMU-N:milk-N) to assess estimated herd DNS and dietary nitrogen use efficiency (DNUE). The analyses included correlations, linear and quadratic regression, and multivariate modelling to determine relationships of herd DNS and DNUE with BMU and BMU-N:milk-N and factors affecting BMU and BMU-N:milk-N. Herd DNS was moderately positively correlated with BMU and BMU-N:milk-N (r = 0.48-0.56, and r = 0.46-0.61, respectively). In contrast, herd DNUE was moderately negatively correlated with BMU and weakly to moderately correlated with BMU-N:milk-N (r = -0.48 to -0.56, and r = -0.38 to -0.49, respectively). Final multivariate models accounted for 51.6-52.8% of the variation in BMU, and 43.6-46.2% of the variation in BMU-N:milk-N. The results suggest that BMU can be used as a near real-time indicator of herd DNS and DNUE in current New Zealand dairy farm systems.

Copper requirements of animals and pastures in New Zealand pastoral agriculture - a review

Jeff Morton — 2024-10-31

More copper (Cu) is required for the growth of cattle and deer than sheep and pasture. National and regional farm surveys showed that mean pasture Cu

concentrations were generally within or above the required range for pasture growth and lambs but below that for cattle and deer. Pasture concentrations of

molybdenum (Mo) of up to 7 mg/kg for lambs and 10 mg/kg for deer had no effect on liveweight gain provided that pasture Cu concentrations

were 7 to 8 mg/kg or greater. From twenty-one sites, there was a significant response to Cu in animal liveweight gain and wool weight only from lambs injected

monthly with Cu and deer grazing pasture top dressed with copper sulphur, both on pasture with high Mo concentrations. Daily drenching of animals with

copper sulphate or chelated Cu and the use of Cu capsules or copper oxide (CuO) wire particles was more effective at increasing liver Cu concentration than Cu

injections or topdressing with copper sulphate. There was a significant pasture yield response measured on Recent and podzolised soils that had pasture Cu

concentrations in the deficient range. There is a need for more research on the response in liveweight gain of cattle and deer from different Cu treatments at

varying pasture Mo concentrations.

Endophyte mixture effects on ryegrass staggers in sheep

Andrew Milsom — 2024-10-31

Epichloë endophytes protect ryegrass from insect pests, but no strain provides both the highest level of insect protection and lowest risk to livestock health. This study examined mixtures of endophytes to find combinations that could mitigate ryegrass staggers in sheep. At Barenbrug NZ, Courtenay, pastures varying widely in sown proportions of perennial ryegrass infected with nea3, nea12 and standard endophyte (SE) were sown in May 2019 and tested with lambs in summer and hoggets in spring 2020. In summer, sown proportions of >65% nea3, <35% nea12 and no SE delayed severe staggers (score 4–5) by 1 week. Alkaloid profiles of these pastures included the tremorgens epoxyjanthitrem I (<0.28 ppm) of nea12 and paxilline (<0.15 ppm) and terpendole C (<1.37 ppm) of nea3. In spring, sown proportions of >65% nea3 and <35% nea12 and/or SE did not induce staggers (score 0–0.1). Those pastures had low concentrations of the potent tremorgen lolitrem B (<0.30 ppm) of SE, epoxyjanthitrem I (<0.39 ppm) of nea12 and paxilline (<0.09 ppm) and terpendole C (<0.41 ppm) of nea3 and SE. The optimal endophyte formulations that minimised staggers across summer and spring were >65% nea3, <35% nea12 and no SE.

Silvopastoral agroforestry systems for dryland corners in Canterbury farms

Sandra Velarde-Pajares — 2024-10-31

Potential future water constraints on dry areas of Canterbury farms, combined with existing animal welfare requirements, have spurred interest in practices such as agroforestry that can help future proof farming. Agroforestry is the deliberate integration of trees within a livestock grazing system. We surveyed farmers to investigate their understanding of agroforestry, including enablers and barriers to change; and conducted a literature review to identify key agroforestry concepts. We partnered with Ngāi Tahu Farming and Claxby Farms in Canterbury Region to co-develop agroforestry planting plans and completed economic analysis of the agroforestry component of each farm. We also identified other unquantifiable potential benefits of integrating trees on farms. We found that the agroforestry systems designed have positive net present value, internal rate of return, and a positive post carbon income annual cashflow. We have demonstrated that agroforestry is potentially economically viable in Canterbury. Agroforestry systems can be designed to align with the New Zealand Emissions Trading Scheme (NZ ETS) and in turn this would provide financial incentives for establishing trees on dryland corners. The quantified economic outcomes and the identified unquantified benefits warrant further research into integrating agroforestry into dairy and other farming systems around New Zealand.

The economic impacts of declining pasture harvest on Northland and Waikato dairy farms

Benjamin Marmont — 2024-10-31

Estimated pasture and crop eaten in Te Tai Tokerau (Northland) and Waikato is decreasing at approximately 0.5 - 1.0 tDM/ha/decade, respectively. espite the falling pasture harvest, milk production has been relatively constant over time due to increased supplement use and farm system changes. Declining pasture harvest trends driven by climate change are likely to continue, and it is essential to understand the impact of this decline on the economic performance of the pastoral sector and to what extent farmer adaptation or potential for enhanced action may mitigate the impact. We combine farm-level data of estimated pasture harvest losses with the Dairy Sector Pathways (DSP) model to estimate how pasture growth may change on dairy farms in Northland and Waikato/Toi Moana (Bay of Plenty). We construct two future scenarios, ‘business as usual’ (BAU) and ‘farmer adaptation (FA).’ Under BAU, pasture growth losses continue at the same rate, offset by increased supplement use. In FA, farmers integrate alternative climate-resilient pasture species into their system, partially mitigating the pasture growth losses experienced under BAU by adopting emergent innovations. We find excess net present value (NPV) associated with FA over that of BAU of $1.3b across Northland, Waikato and Bay of Plenty regions. The estimated pasture losses are not faced by dairy alone, with the wider pastoral sector requiring forages resilient to climate change. Developing forages resilient to climate change might seem like a problem specific to Northland, but given enough time, regions to the south may face similar conditions. Therefore, identifying resilient forages and designing adapted farm systems supported by extension networks is critical to the future of pastoral farming in New Zealand.

Impacts of winter crop choice and ewe body condition score change on whole farm profitability and production

Anna Taylor — 2024-10-31

Variations in body condition score (BCS) in ewes influences lamb survival, ewe survival and ewe lactation performance. Feeding a low protein diet such as fodder beet to ewes in mid-to-late pregnancy increases lamb losses and reduces lamb weaning weight even further. However, using high yielding forages such as fodder beet can reduce the area of winter crop required, introducing potential whole-farm benefits which may alter profitability. We analysed the effects of winter crop choice (brassica or fodder beet) and BCS (maintaining or reducing) on whole-farm production and profitability, using a targeted supplement to offset the impacts of fodder beet feeding. Eight farms were selected to represent low or high rainfall (590 and 1090 mm/annum respectively) regions of the South Island. Impacts of changing BCS on ewe and lamb survival at lambing, and lamb liveweight gain to weaning were calculated when fed either adequate (brassica) or low protein (fodder beet) diets in mid-to-late pregnancy. Production statistics and profitability were calculated using Farmax. Whole farm profitability was analysed using BCS change and winter forage crop as main treatments, blocked by low or high rainfall. Applying the effects of BCS and low protein diets on reproductive performance from prior published studies resulted in variation of 102 to 141 lambs weaned per 100 ewes mated, with the lowest value when the low protein, fodder beet only diet was used. Greatest number of lambs weaned was achieved when BCS was maintained through winter through provision of a balanced supplement, regardless of winter forage diet (P<0.05). Lamb sale dates were later when fodder beet was used, due to lower lamb weaning weights, resulting in marginally higher prices due to changes in pricing schedule. Farm profitability was increased by 25% when BCS was maintained though winter (P<0.05) irrespective of the diet used. Use of fodder beet must be accompanied by targeted supplementation to avoid ewe BCS loss increased lamb losses and the negative effects on wastage and animal welfare. Extra profitability could only be generated by opportunities to sell surplus feed during the summer. These responses were similar in both high and low rainfall environments. This study is unique in testing measured responses of BCS and targeted nutritional supplementation under specific physiological conditions on whole-farm profitability. Farmer decisions on feed utilisation and sale also have a significant influence on the potential to mitigate the effects of variations in winter forage choice.

Automating dairy farm grazing records using GPS technology

Wayne Hofmann — 2024-10-31

Long-term grazing records can be used to assess paddock productivity (e.g., grazings per year), yet inconsistent record-keeping among New Zealand farmers hampers accurate analysis. Recently, GPS ear tags have emerged as an automated solution for identifying and recording paddocks grazed, providing data that could be used to underpin on-farm decisions and aid sector scale tracking of pasture productivity. Two GPS-enabled ear tags (GSatSolar and Ceres Trace) powered by solar energy and reporting direct-to-satellite were evaluated on two Waikato dairy farms for recording grazing events. Five cows were fitted with GSatSolar ear tags on each farm, and a further four were fitted with Ceres Trace ear tags on the second farm. Comparing the GPS location data with manual grazing records revealed varying levels of accuracy in identifying the grazed paddock. The grazing records inferred using the GSatSolar ear tags correctly matched the manual grazing records on 58% of occasions on the first farm and 85% on the second farm, with the difference being attributed to the number of working devices between farms. By comparison, the Ceres Trace ear tags identified the grazed paddock on 91% of occasions. These findings suggest that it is feasible to automate the recording of on-farm grazing events using GPS-enabled devices. However, a greater number of devices should be deployed, and/or the location reporting frequency must be increased to identify the grazed paddock accurately. The considerations when choosing devices for these purposes are also discussed, including reporting frequency and tag attachment methods.

Assessing the validity of sensor-based predictions of post-grazing residual in dairy systems

Wayne Hofmann — 2024-10-31

Knowledge of post-grazing residuals are crucial for dairy farmers to adjust feed inputs and optimise pasture utilisation. However, many farmers rely on subjective methods, like visual assessment, to make grazing decisions. This case study evaluation applied a predictive model for post-grazing residuals, based on previous research, to two farms: a research dairy farm with smaXtec rumen boluses divided into three farmlets (alternative pastures, current and low emissions) and a commercial dairy farm with cows equipped with AfiCollars. The aim was to assess the model’s performance in an uncontrolled environment. There was some alignment between the predicted post-grazing residuals from the sensor-based model and the farm-walk data. However, the model’s explanatory ability was poor, with R² values calculated as the coefficient of determination ranging from -1.31 for the alternative pastures farmlet to 0.05 for the current farmlet and 0.15 for the low emissions farmlet. On the commercial farm, the R² was -1.12. While previous studies have demonstrated the potential of predicting pasture residuals from animal sensors, our study identified some challenges that would need to be overcome for broader application, including variations in on-farm management practices (e.g., supplement usage, frequency of pasture allocation, and mulching) and pasture species diversity. Given the infancy of this approach, further research is necessary to refine the predictive capabilities and clarify the specific contexts where its use could benefit New Zealand farmers.

Pasture performance tools: Current and future state

Sarah Gard — 2024-10-31

Measuring pasture biomass is critical to inform pasture management for optimised utilisation.
Traditional techniques for measuring pasture performance are time-consuming and costly. Emerging pasture performance tools were assessed for accuracy, availability (of the tool and of data collected), calibrations used in development, and limitations.
Considerable efforts have been made with new tools to reduce the time and effort required to measure pasture performance, although limitations of accuracy remain, associated with calibration methods used in development. Promising future technologies will involve greater ground truthing for validation and fusion of multiple data sources.

Combining positional data with climatic and landscape data to understand the interaction of cattle with their environment

Alison Spera — 2024-10-31

This research provides proof of concept of integrating data from a range of sources by defining landscape use by cattle under different climatic conditions. Digital technologies provided data representing the climatic, geospatial, soil and pasture properties to characterise the grazing environment. Virtual herding technology defined animal position and activity. Data was collected at Waipori Station, a Pamu owned high-country sheep and beef farm of approximately 9,271 effective hectares, located in Otago, New Zealand about 60 kilometres west-northwest of Dunedin (-45.8410008°S, 169.7966283°E). Three hundred and two rising-3-year-old first calving cattle with calves at foot were monitored in two 65 ha paddocks from February to May 2022. Cattle used various parts of the landscape
in different climatic conditions. Placement of cattle in sensitive parts of the catchment was identified. Activity patterns were also altered by climatic conditions. These insights, using integrated data sets, can guide farmer decision-making to reduce environmental impact and achieve animal welfare needs while optimising utilisation of the landscape when deploying virtual herding technologies. Further work is required to develop both the data storage systems and the protocols and algorithms to achieve successful integration.

How to improve the legacy value of your dataset?

Carmen Teixeira — 2024-10-31

Evaluating management strategies for a pasture-based extended lactation system with 24-month calving intervals

Lydia Farrell — 2024-10-31

Extended lactation (EL) systems, with calving interval voluntarily extended beyond 12 months, may alleviate dairy sector challenges of labour scarcity and non-replacement calves. This study used bio-economic simulation to investigate how the profitability of an EL system could be improved through strategic management and tested system robustness across different climate and economic years. An EL system with half of cows calving each spring at 24-month intervals was compared with a conventional (Control) system calving all cows each spring. Both systems were modelled with Ruakura climate and Friesian cows at 2.8 cows/ha with > 80% of feed from grazed pasture. Profitability of the EL system was better during years with greater pasture growth, particularly in summer and autumn, and in years with low supplement feed costs relative to milk price. The EL system profitability was improved by shortening grazing rotations in autumn and winter to harvest more pasture. Overall, a strategically managed EL system could achieve similar or improved production, profit and environmental outcomes to Control, provided the herd achieves similar days in milk to the control and has sufficiently lower feed, health and breeding expenses.

Condensed tannin expression in white clover leaves for enhanced animal health benefits

Marissa Roldan — 2024-10-31

Rapid consumption of lush white clover foliage can cause bloat which, in severe cases, can lead to animal death. One way of mitigating against this is to provide a moderate level of condensed tannins (CTs) in the diet. Unfortunately, CTs are largely absent in white clover leaves. Insertion of a transcription factor gene that encodes a CT ‘master switch’ from a distantly related clover species enabled stable production of biologically significant levels of CTs in white clover leaves. Leaf CTs reduced methane emissions in rumen fluid in vitro, however, in high CT producing genotypes, a yield penalty of up to 50% was incurred. To alleviate this issue, genotypes with good herbage yield and CT levels >1.5% of DM were backcrossed to the elite cultivar Mainstay over several generations. Recurrent plant selections, both in the glasshouse and the field, have delivered white clover with commercially acceptable herbage yield combined with a biologically significant level of leaf CTs. Under laboratory conditions clover leaves containing CTs >2.0% DM effectively reduced frothy foam and biofilm formation (P<0.01). Since these are indicators of bloat incidence, this development has the potential to enhance animal health in addition to reducing greenhouse gas emissions.

Animal performance over 16 years after implementing a lucerne grazing system on Bog Roy Station - a case study

Derrick Moot — 2024-10-31

In 2023, the animal performance data for Bog Roy station show 151 t weaned lamb is being produced from 4272 ewes plus 9.0 t from hogget lambs. The ability to mate merino hoggets has resulted from increased feed supply that means mixed age ewes are now consistently averaging 65.6±1.17 kg/hd at mating (2019-2023). This has enabled an emphasis on two-tooth weight at mating, which has also increased 0.74±0.14 kg/hd/yr (R² = 0.64) from 52 kg/hd in 2012 to 61 kg/hd in 2023. Consequently, scanning is consistently ~167±1.59% for the mixed age ewes (2012-2023) and increased from 113% (2008) to 154% (2023) in the two-tooths. Lamb wastage for the mixed age ewes has decreased 0.70±0.08%/yr (R² = 0.88) to 15% in 2023 and, although more variable (R² = 0.13), the wastage in two-tooths has also reduced from 32% (2014) to 21% (2023). Lamb wastage is negatively related to two-tooth weight at set-stocking, so feeding young stock is a priority. Since 2016, pre-weaning merino lamb growth rates have averaged 286±4.39 g/hd/d with weaning now at 79.3±2.56 days. This consistency coincided with the addition of 210 ha of feed under pivot irrigation that was initially sown in red and white clover and is now in lucerne/grass mixes. The additional feed has meant wool production has remained constant throughout the 15 years of pasture development. Cow numbers have been used to buffer the changes in pasture supply as the dryland and pivot development occurred. These have now increased to their highest level since the development began. The major change in farm income has resulted from the earlier sale of more lambs at a higher average price because they are heavier due to the extra feed. This unique long-term dataset of on-farm performance provides a commercial example of transformational change that has resulted from changes in the farm system, driven by direct feeding of dryland lucerne and irrigation development focused on growing young stock in this 420 mm rainfall environment.

Exploring potential dairy and arable farm system integration to enhance nutrient circularity: A case study analysis from Oamaru's coastal plains

Banira Lombardi — 2024-10-31

The evolving challenges facing New Zealand's agricultural sector, particularly in dairy and arable farming, include rising costs, regulations, and environmental sustainability goals. In response, this study evaluated the potential benefits of enhancing nutrient circularity in a collective dairy and arable farming system aimed to reduce synthetic fertiliser use, lower greenhouse gas (GHG) emissions, and decrease nitrogen (N) leaching. Using an “Innovation System Approach” that included Farmax Dairy and OverseerFM, a North Otago dairy and arable farm system was modelled to compare current practices with two scenarios aimed at optimising manure use for arable production. Scenario 1 introduced an off-paddock facility for restricted autumn grazing and wintering cows, with collected manure applied to arable crops. Scenario 2 included a pasture phase in the arable farm's crop rotation for dairy grazing and fertilised arable crops with effluents on the dairy platform. Both scenarios significantly reduced synthetic fertiliser inputs through their partial substitution with manure. N leaching decreased by 8-17% due to reduced N fertiliser use and excreta returns to the dairy platform. On-farm GHG emissions were effectively unchanged (1% decrease) due to pollution swapping. These results highlight the potential benefits of circular farming practices in NZ’s dairy and arable farming systems, improving resource-use efficiency and mitigating environmental impacts through optimised nutrient supply and manure management.