Department of Agricultural Sciences

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https://hdl.handle.net/10182/34

The Department of Agricultural Sciences consists of animal science, plant science and farm management and agribusiness staff members.

The range of research conducted is quite extensive including: conversion of forests into pasture, alternative dryland pasture species, grain legume agronomy, sustainability in farming systems, nitrogen fixation and nitrogen cycling, shelter on dairy farms, economic viability of NZ farming systems, animal nutrition, immunology etc.

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Open Access
Ryegrass endophyte mixtures for improved animal health : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Milsom, Andrew
In New Zealand, perennial ryegrass (Lolium perenne) with endophyte (Epichloë festucae var. lolii) is a standard ingredient of pastures where insect pests challenge the persistence of the ryegrass. Farmers currently have multiple ryegrass cultivar x endophyte strain combinations from which to choose the best match for their requirements. However, no single cultivar x strain combination provides both the highest insect protection and lowest occurrence of ryegrass staggers and heat stress in animals grazing pasture with endophyte. Furthermore, the current industry protocol for testing the safety of animals grazing a grass x endophyte combination involves exposing the animals to a simulated worst- case scenario and needs reassessment. This research aimed to examine the effects of endophyte diversity in perennial ryegrass on the health and performance of sheep using a modelling approach so that an animal response of any mixture could be predicted as a function of the mixture’s endophyte proportions, thus minimising the need for animal testing in the future. At Barenbrug Plant Breeding Station, Courtenay, Canterbury, eight pasture treatments of Maxsyn perennial ryegrass – seven that varied widely in sown proportions of three endophyte strains – nea3, nea12, and standard endophyte (SE) – and an endophyte-free control (nil), were tested over four experimental runs from February 2020 to December 2021. There were three monocultures (100% of each strain), three binary mixtures (50% of each of two strains) and one ternary mixture (33.3% of each strain) of endophyte based on a simplex centroid design. The eight treatments were randomised in three blocks of 0.156-ha plots. The animal responses of interest were ryegrass staggers, liveweight gain, heat stress, and diet selection of grazing sheep. The first experiment run was a test for ryegrass staggers in February 2020. Endophyte toxicity in late summer is typically near its annual maximum in Canterbury, so the timing of this run created a ‘worst-case scenario’ for ryegrass staggers. The pastures were managed in the previous spring so as to accumulate a large herbage dry matter (DM) mass (about 3700 kg DM/ha above a cutting height of 40–50 mm) of low nutritive quality feed (metabolisable energy (ME) = 8.7 MJ/kg DM and crude protein (CP) = 4.9%). The pasture available (kg DM/ha) was high enough for lambs to remain in the same plots for a 4-week testing period at a stocking rate of 64.1 lambs/ha. Ryegrass staggers was severe (score 4–5) in the lambs grazing the SE pasture after 8 days and in all other endophyte monocultures and mixtures after 22 days. Mixture models fitted to the staggers response data predicted the staggers score for any combination of sown endophyte proportions and identified an optimum of 65% nea3 and 35% nea12 which delayed severe staggers by 1 week. Ryegrass staggers was associated with tremorgenic alkaloids in the herbage above 40–50 mm: epoxy-janthitrem I of nea12 (1 ppm), paxilline and terpendole C of nea3 (0.1 and 1.2 ppm), and lolitrem B, paxilline and terpendole C of SE (2.2, 0.2, and 1.1 ppm). The second experimental run was a study of liveweight gain and ryegrass staggers under low toxicity conditions from September to December 2020. The spring pastures provided optimal conditions for liveweight gain and the stocking rate was kept consistent at 44.9 hoggets/ha. Pre-grazing pasture mass was ca. 1600 kg DM/ha, ME was 12 MJ/kg DM and CP was 20% above 40–50 mm. The average daily gain for all mixtures was 271 g/day over the first 4 weeks, and 20 g/day for weeks 4–8. The mixture models fitted to the liveweight gain data identified the optimum endophyte formulation that maximised liveweight gain to be a monoculture of nea12 so that the responses were equal to the monoculture performance in the first and second 4 weeks of grazing (292 and 25 g/day). Ergovaline, the alkaloid linked to suppressed liveweight, was present in nea3 and SE pastures at 0.32 and 0.16 ppm. Staggers scoring at the onset of symptoms after 10 weeks of grazing revealed mild staggers (score <2) in SE that persisted until the experiment ended at 12 weeks. The model analysis showed that any mixture containing at least 60% nea3 and up to 40% nea12 and/or SE would result in no staggers (score 0). Alkaloids associated with staggers were in lower concentrations compared to the summer test: 0.8 ppm of epoxy-janthitrem I was present in nea12 pastures while lolitrem B, paxilline, and Terpendole C were present in SE pastures at 1, 0.1, and 0.3 ppm. The third experimental run tested the assumption that endophyte strain proportions in the diet were equal to the sown proportions. Plot fences within replicates were removed, 51–56 hoggets were allocated to each replicate (40.9–44.9 hoggets/ha), and sward height decrease was measured 15 times between 15 February and 16 March 2021. Herbage mass, ME, and CP values at the beginning of grazing were circa 1400 kg DM/ha, 11.5 MJ/kg DM, and 11%. Analysis of variance showed no differences (P>0.05) in sward height decrease between sown treatments, including nil, over the whole grazing period. Mixture models of each measurement date and the average of all dates only showed differences (P<0.05) between linear terms (monocultures) on day 2 and further analysis confirmed the sward height decrease of SE was greater than nea12 (P<0.05), but not nea3. Quadratic terms (binary mixtures) were not different on any date. The mixture model analysis for the whole period predicted that a mixture containing 39% nea3 and 61% SE would maximise sward height decline despite lolitrem B concentrations of SE pastures being sufficient to cause ryegrass staggers (1.4 ppm) and ergovaline levels in nea3 pastures of 0.37 ppm. The lack of deterrence to these alkaloids indicates that animals were unable to differentiate between endophyte strains. The fourth experimental run was a repeat liveweight gain test followed by a heat stress study from October to December 2021. Pasture conditions were similar to the previous liveweight gain test at the start of grazing (ca. 2400 kg DM/ha, 12 MJ ME/kg DM, 15% CP). The same number of hoggets were used as in the previous liveweight gain study, but a higher starting liveweight and greater pre- grazing pasture mass resulted in greater liveweight gain across mixtures in the first and second 4 weeks (397 and 67 g/day) compared to the previous spring. The model analysis predicted an optimum mixture containing 16% nea3, 65% nea12, and 20% SE would result in maximum liveweight gains of 402 and 85 g/day in the first and second 4 weeks of the test. Data loggers attached to controlled internal drug release (CIDR) devices recorded vaginal temperatures in selected mixtures (nea3, nea12, nea3–nea12, and nil) during the final 8 days of the 8-week grazing period. Average temperature for the three mixtures was 39.07°C compared to 38.96°C in the nil endophyte control. Hoggets grazing nea12 had the lowest temperature of the three mixtures (38.94°C; P<0.05). Consequently, the mixture model predicted the optimum mixture would only contain nea12. Ergovaline concentrations were 0.7 and 0.5 ppm in nea3 and SE. An endophyte diversity model that included ryegrass staggers and liveweight gain responses from experimental runs 1, 2, and 4 as multivariates, predicted a mixture containing 77% nea12 and 23% nea3 would give the best overall combination of responses. Although temperature was not included in the model, the vaginal temperature response of this optimal mixture was predicted to be 39.02°C, just 0.06°C higher than the nil endophyte control. This thesis showed that endophyte mixtures can improve the health of grazing sheep and provides the industry with a new option for mitigating health issues associated with endophyte without searching for novel strains. Such mixtures would be best suited to scenarios where insect pest pressure requires the use of endophyte strains that can increase the risk of ryegrass staggers and/or suppressed liveweight gain. The endophyte diversity modelling approach can predict responses to sown strain proportions beyond those included in the experiment, reducing the number of animal entries required for testing.
Restricted
Response of pasture plants to shade in agroforestry and agrivoltaic production systems
(Edited by the American Forage and Grassland Council and Published by Curran Associates Inc., 2023-01-01) Kirschten, H; Graham, M; Ates, S; Maxwell, Thomas; Rosati, A
Agrivoltaics production systems have gained traction globally, holding promise to supply energy and food concurrently from the same unit of land. Studies investigating shade tolerant crops to optimize production under solar panels have mostly followed the findings of agroforestry studies. However, spectral composition of transmitted radiation in agrivoltaic and agroforestry production systems may not be the same, inducing different shade responses of understory crops. A pot trial investigating the effect of shade source on biomass production and morphology of perennial ryegrass, ribwort plantain and white clover was established during spring, in Oregon, USA. Treatments were solar panel shade, hazelnut tree shade and no shade. Ryegrass plants located under tree shade were lighter (0.18 g/plant; P<0.01) but taller (38 cm) compared to those grown under solar panel shade (0.48 g/plant; 31 cm) and in open areas (0.59 g/plant; 13.3 cm). In contrast, 2.4 tillers/plant under tree shade were recorded compared to 5.6 and 9.2 tillers/plant under solar panel shade and open areas, respectively. Root length of ryegrass was similar in open areas (27.5 cm) and under solar panels (30.9 cm) but shorter (P<0.01) under tree shade (17.3 cm). Plantain grown under tree shade was taller (P<0.01) than under panel shade, and shortest in open areas, though having more leaves (11.3/plant; P<0.01) than under trees (6.6/plant) and panel shade (8.1/plant). However, plant DM weight did not differ between shade regimes (P=0.47). Root length of plantain grown under solar panels was longer (17.4-23.3%) than in open and tree shade areas. White clover grown under solar panels were almost 2.5 times taller than in open areas. Stolon numbers and lengths were not affected by shade treatments. Our results indicate substantial differences in shade quality induced by solar panels and hazelnut trees, thus affecting understory forages differently.
Open Access
A review of pasture yields and growth rates in Northland
(Taylor & Francis Group, 2023) Teixeira, CSP; Olykan, ST; Moot, Derrick
Pastoral grazing is the major land use in Northland, New Zealand. This study analysed the distribution and variability of pasture dry matter (DM) yields across four distinct physiographic regions, using published and original unpublished datasets collected from 1958–2021. Dargaville had the highest mean annual pasture yield of 11900 kg DM/ha, Kaitaia 9970 kg DM/ha and Kaikohe and Whangarei at ∼8400 kgDM/ha. Pasture water use (DM yield/mm rainfall) ranged from 10.8 kg DM/mm/ha (Kaikohe) to 16.4 kg DM/mm/ha (Dargaville). Kaitaia showed the largest annual yield variability (>2300 kg DM/ha). The relationship between pasture growth and temperature was quantified to estimate temperature adjusted growth rates for these regions. Whangarei spring growth was low at 3.19 kg DM/°Cd before it declined after 2560°Cd, or ∼7630 kg DM/ha, to 1.85 kg DM/°Cd, due to summer dry conditions. These results suggest pasture production was low compared with other regions of New Zealand. The low production and persistence may be compounded by the lack of readily available supplementary feed during summer dry or winter wet conditions. This increases the risk of overgrazing which reduces plant reserves and total light interception which results in physical damage to pasture plants and lower than potential yields.
Open Access
Elevated carbon-dioxide effects on wheat grain quality differed under contrasting nitrogen and phosphorus fertiliser supply
(Wiley-Blackwell, 2024-01) Chakwizira, E; Dunbar, HJ; Andrews, M; Moot, Derrick; Teixeira, E
Atmospheric carbon-dioxide concentration ([CO₂]) is increasing rapidly, but its interactions with nitrogen (N) and phosphorus (P) fertiliser on wheat grain quality are not well understood. We investigated the effects of ambient CO2 (aCO₂; ∼410 ppm) and elevated CO₂ (eCO₂; 760 ppm) on crop harvest index (CHI), nutrient harvest index (NuHI), shoot macro-nutrient content and grain macro-nutrient concentration of wheat grown under two contrasting amounts of N (0.5 and 6 mol m¯³ NO₃‾ N) and P (10 and 250 mmol P m¯³) fertiliser supply (low and optimum, respectively). Our results highlighted interactions between [CO₂] and N and P fertiliser supply for the shoot biomass at anthesis and straw biomass at harvest maturity. This was because biomass yield did not respond to CO₂ level when fertiliser was deficient. However, shoot and straw yield increased (10.0–-34.0%) with increasing [CO₂] at optimum fertiliser rates. Across experiments, grain yield increased (15.6%) with increasing [CO₂], which resulted in grain nutrient concentration decreasing (3.0–-13.0%) with increasing [CO₂]. This was attributed to nutrient 'dilution' due to increased carbohydrate content in the grain. Overall, fertiliser supply impacted crop responses more than CO₂ treatments, and the impact was greater under N than P deficiency. This was reflected through conservative values for CHI, thousand grain weight and NuHIs suggesting plants allocated biomass and nutrients at similar rates for vegetative and reproductive organs independent of [CO₂].
Open Access
Phenological development of subterranean clover (Trifolium subterraneum L.) in New Zealand in response to different climate change scenarios
(Elsevier B.V., 2023-10) Guo, J; Teixeira, CSP; Sood, A; Moot, Derrick
Climate predictions for New Zealand for the coming decades suggest rising temperatures (+0.7–3 °C), increased diurnal temperature and variable precipitation patterns that differ around the country and with seasons. The most common pattern of annual precipitation indicates the largest increases in the west of the South Island and the largest decreases in the east of the North Island and coastal Marlborough. The phenophases of subterranean clover were estimated and quantified using a thermal time-based model under different climate scenarios based on greenhouse gases and aerosol pathways over the 21st century, known as the Representative Concentration Pathways (RCPs), at two periods (mid and end of the century). The estimated flowering (R3) and post- flowering (R6-R11) date change showed a consistent trend across all districts. The largest date advances (≥ 5 days) were predicted for the three current latest flowering districts (Mackenzie, Queenstown and Central Otago). A reduction of the plant's life cycle, for both ‘Early’ and ‘Late’ maturity cultivars may have undesired consequences for forage yield so genetic material with later flowering dates may be useful. Adaptation strategies to mitigate the future warming effects include using ‘Late’ flowering cultivars and greater use of supplementary feed through summer dry conditions.
Open Access
Predicting yield of irrigated red clover (Trifolium pratense L.) pastures in response to temperature
(New Zealand Grassland Association, 2023) Keenan, LJ; Mills, A; Smith, MC; Brown, HE; McKenzie, SM; Moot, Derrick
Two datasets from red clover monoculture pastures grown in Lincoln, New Zealand, were analysed to generate coefficients to predict red clover yield. The mean annual production of established red clover was 17.0±0.48 t DM/ha, with a maximum mean growth rate of 125±9.36 kg DM/ha/day (spring Year 2). In the establishment year irrigated red clover grew at a constant rate of 7.30±0.14 kg DM/ha/°Cd (Tb = 3 °C) throughout the year. In contrast, there was a split-line linear response in Years 2 and 3, which differed between years and decreased after the second week of January. Specifically, the growth rate in Phase 1 was 7.70±0.38 kg DM/ha/°Cd in Year 2, which was 16% higher than the 6.60±0.28 kg DM/ha/oCd in Year 3. The difference probably reflected increased competition from weed grasses as red clover content declined from >95% to ~75% of total annual yield. After January, red clover grew at 3.05±0.35 kg DM/ha/°Cd, in both years. This lower rate occurred in the mid-January-July period, and probably reflected a change in partitioning of assimilate to red clover roots in response to a decreasing photoperiod. The coefficients reported here for red clover need to be validated from other datasets. However, they provide easily transferable coefficients that can be used to estimate red clover yield under non-limiting conditions for other locations. These could be integrated into feed budgeting software to assist on-farm decision making.
Open Access
Hill country futures - Resilient farmers and forages for the future
(New Zealand Grassland Association, 2023) Keeling, SE; Sutherland, MA; Moot, Derrick; Dixon, KM; McFetridge, AN; Odgers, NP; Millner, JP; Ropiha, JPK; Ludemann, CI; Barker, AR; Brier, DE
A thriving hill country farming sector is crucial for New Zealand’s economy and its regions. However, it faces numerous challenges, such as increased regulations, and changing societal expectations. To ensure the long-term success and well-being of farmers, farm systems, the environment, and rural communities, support is essential for building lasting resilience. To address some of these challenges, the Hill Country Futures Partnership programme was initiated, receiving $8.1 million funding over five years. This programme, co-funded by Beef + Lamb New Zealand (B+LNZ), the Ministry of Business, Innovation and Employment, PGG Wrightson Seeds, and RAGT New Zealand, concluded in 2023. During the programme, the farming community were actively engaged, and a collaborative research approach was employed involving B+LNZ, farmers, universities, Crown Research Institutes, and consulting agencies. The programme consisted of interconnected workstreams with a focus on resilient farmers and future-oriented forages. It generated a wide range of resources, including easily accessible extension materials, tools, and scientific publications, covering social, environmental, and technical aspects to support New Zealand’s hill country farming systems. And it showed how a collaborative approach, inclusive of researchers and farmers with diverse backgrounds and expertise, can help create a more resilient hill country future.
Open Access
A review of grass species yields and growth rates in Northland, New Zealand
(Taylor & Francis, 2024) Teixeira, CSP; Olykan, ST; Moot, Derrick
Pastoral farming is a major land use in New Zealand's Northland region, with 3,171 farm holdings and a total area of 637,500 hectares in 2022. The region's pasture grasses include temperate (C3) and subtropical and tropical (C4) grasses which support dairy, and sheep and beef production from grazing. In lowland areas, C3 and some annual C4 grasses are prevalent where cultivation occurs, while perennial C4 grasses dominate areas with low soil fertility and summer dry conditions. Grass-based pasture growth rates (kg dry matter/ha/day) from published and unpublished sources were assembled into the AgYields database. Among the resident and sown grasses tested in Kaitaia, Kaikohe, Whangarei and Dargaville, perennial ryegrass represented ∼60% of the total data points. Dominant kikuyu pastures represented 23% and the remaining species represented 17%. Rates of growth ranged from 5 to 120 kg DM/ha/day, being lowest in late autumn-winter and highest in early summer. Data were compared and agronomic traits (i.e. drought tolerance, biomass production and tillering) are discussed to assess species suitability for the Northland environment. The medium-term prospect suggests an urgent need to improve research into management of cocksfoot and tall fescue-based pastures to provide viable alternatives to overcome the decreasing persistence of perennial ryegrass.
Open Access
Yield and persistence of legume monocultures grown in the Lees Valley, South Island High Country
(New Zealand Grassland Association, 2023) Olykan, ST; Mills, A; Lucas, RJ; Smith, M; Moot, Derrick
Six legume monocultures were established in the Lees Valley, North Canterbury (400 m a.s.l.), which has long cold winters. The stony soils have low pH, high aluminium concentration, and low water holding capacity, which can lead to severe summer soil moisture deficits. The aim was to identify legumes that would survive and persist in this environment and, therefore, increase the available nitrogen in the pastoral system. Legume populations of 88±12 seedlings/m² were established and ranged from 45 (sub clover) to 197 seedlings/m² (Caucasian clover). The highest yields were from ‘Pawera’ red clover at 2.5 and 2.9 t DM/ ha in Years 2 and 3, ‘Demand’ white clover produced 1.7 and 2.6 t DM/ha, and ‘Endura’ Caucasian 1.8 and 1.7 t DM/ha. ‘Kaituna’ lucerne yields were low at 0.7 and 1.4 t DM/ha. Caucasian clover was the most persistent legume. A visual assessment in Year 5 found Caucasian was the only legume still dominating its plot (69%) with the lowest area of bare ground (11%). ‘Leura’ subterranean and ‘Bolta’ balansa annual clovers survived for four years but accumulated annual yields were low (<1.0 t DM/ha/yr), and the presence of unsown species was high (>50%). While red and white clover provided the highest yields for two years, Caucasian clover was the most persistent species and is therefore a legume recommended for this environment.
Open Access
Pasture production: A compilation of historical datasets from farms in Bay of Plenty
(New Zealand Grassland Association, 2023) Teixeira, C; Gee, T; Hawke, M; Moot, Derrick
Bay of Plenty district, and particularly the Rotorua Lakes area, has a diverse terrain and soil types which influence pasture production. Regular measurement of pasture production enables short term decision making on a farm scale and is invaluable for catchment, district and regional long term management strategies. Thomas (Tom) M. Gee, was a retired farmer with more than 18 years of field trial experience with MAF Field Research Division. He collected data from more than 30 farms after he retired. Data from other sites in the district were collected in the early 1970s by MAF technicians stationed in Whakatane and Tauranga and later by AgResearch staff and a farm consultant based in Rotorua. Tom Gee’s mission was to use these measurements to provide farmers with rates of growth (ROG) data to inform them about their farm. The Gee farm (Fairbank) of 200 ha was originally leased from Ngati Whakaue Tribal Lands in 1916 and then purchased before much of it was sold back to the Incorporation in 1970. Tom retired in 1989 but kept meticulously recording pasture growth rates on different farms up to ~ 2007. Some field notes were lost, but datasets with gaps are still useful to assist monthly growth rates calculations. His valuable and extensive (almost 25 years) on farm field records have been retrieved, compiled, assembled, and digitised, to be saved electronically, and entered into the AgYields National Database hosted at Lincoln University. Part of this legacy dataset has been summarised and dry matter yields and growth rates calculated, consistent with previous methods, to provide a quantified description of mean monthly pasture growth rates across the Bay of Plenty region, in New Zealand.
Open Access
Legume yield and persistence in grass and herb pasture mixtures in Lees Valley, South Island High Country
(New Zealand Grassland Association, 2023) Olykan, ST; Mills, A; Lucas, RJ; Smith, M; Moot, Derrick
Four experiments were established to identify productive and persistent dryland pasture mixtures that included legumes to supply nitrogen and a suitable grass and/or herb companion species. There was a Caucasian clover-herbs (plantain and/or chicory) mixture experiment, and three grass-clover mixture experiments: ryegrass cultivars, dryland grass species (brome, cocksfoot, or tall fescue), or timothy +/-herbs (plantain and/or chicory), all sown with white and sub clovers. The site was in Lees Valley, an intermontane basin in North Canterbury (400 m a.s.l.), which experiences long cold winters, has soils of low pH and high aluminium, with low water holding capacity and severe summer soil moisture deficits. In the first two years of the grass-clover mixtures, the ryegrass and dryland grass-clover pasture mixtures were the most productive with total yields of ~4,400 kg DM/ha. In the dryland grass mixtures, the yield of the brome and cocksfoot grass component increased from Year 1 to 2 (1350 to 2830 kg DM/ha) while tall fescue declined (970 to 800 kg DM/ha). The equivalent timothy grass yields were low averaging ~320 kg DM/ ha/yr. Across the grass-clover mixtures, the average white clover yield was 1800±210 kg DM/ha in Year 1 and represented 43% of total DM, compared with 8% sub clover. In Year 2, the white clover produced 930±90 kg DM/ha, which represented 29% of total annual yield. Sub clover did not re-establish. Grass cultivars/species in the mixture experiments had no effect on white clover yield. White clover yields peaked in October-November of both years with growth rates of ~16 kg DM/ha/d. At the start of the summer dry period, from November onwards, white clover growth rates declined resulting in lower yields. In the Caucasian-herbs experiment, total yield in Years 1 and 2 was ~2750 kg DM/ha/yr. In both years Caucasian clover yields were lower when grown in herb-based mixtures compared with a monoculture (Year 1: ~400 versus 1800±270 kg DM/ha, Year 2: 920 versus 1750±210 kg DM/ha). Plantain contributed ~1740 kg DM/ha/yr to the total yield. The persistence and productivity of grass-legume-herb mixtures for dryland pastures are discussed. Cocksfoot was a productive grass in Lees Valley because of its aggressive growth habit and resilience in dryland conditions. Caucasian clover was a productive when grown as a monoculture.
Open Access
Unveiling a microexon switch: novel regulation of the activities of sugar assimilation and plant-cell-wall-degrading xylanases and cellulases by Xlr2 in Trichoderma virens
(MDPI, 2024-05) Castañeda-Casasola, CC; Nieto-Jacobo, MF; Soares, A; Padilla-Padilla, EA; Anducho-Reyes, MA; Brown, C; Soth, S; Esquivel-Naranjo, EU; Hampton, John; Mendoza-Mendoza, A
Functional microexons have not previously been described in filamentous fungi. Here, we describe a novel mechanism of transcriptional regulation in Trichoderma requiring the inclusion of a microexon from the Xlr2 gene. In low-glucose environments, a long mRNA including the microexon encodes a protein with a GAL4-like DNA-binding domain (Xlr2-∝), whereas in high-glucose environments, a short mRNA that is produced encodes a protein lacking this DNA-binding domain (Xlr2-β). Interestingly, the protein isoforms differ in their impact on cellulase and xylanase activity. Deleting the Xlr2 gene reduced both xylanase and cellulase activity and growth on different carbon sources, such as carboxymethylcellulose, xylan, glucose, and arabinose. The overexpression of either Xlr2-∝ or Xlr2-β in T. virens showed that the short isoform (Xlr2-β) caused higher xylanase activity than the wild types or the long isoform (Xlr2-∝). Conversely, cellulase activity did not increase when overexpressing Xlr2-β but was increased with the overexpression of Xlr2-∝. This is the first report of a novel transcriptional regulation mechanism of plant-cell-wall-degrading enzyme activity in T. virens. This involves the differential expression of a microexon from a gene encoding a transcriptional regulator.
Open Access
Five-year old diversified pasture supports greater lamb liveweight gain than a standard perennial ryegrass-white clover pasture
(New Zealand Grassland Association, 2023-03-01) Maxwell, Thomas; Cartwright, HS; Meyer, JL; Al-Marashdeh, Omar
This study investigated liveweight gain of lambs grazing five-year-old pasture of either Italian ryegrass, red clover and plantain (Diversified) or perennial ryegrass and white clover (Standard). Coopworth lambs were born to either diversified or standard pasture and reared there until weaning in December (early summer). Liveweight gain (LWG) from tailing to weaning was 23% higher in lambs on diversified pasture (0.335 kg LWG/lamb/day) compared to those on standard pasture (0.272 kg LWG/lamb/day). From summer to autumn (December to May), liveweight, pasture mass, botanical composition and nutritive quality was measured as weaned lambs progressed through rotationally grazed paddocks of either diversified or standard pasture. Similar lamb liveweight gain between pasture types was observed over summer and autumn, with both groups averaging 0.187 kg LWG/lamb/day. From December to May, dry matter intakes (DMI) and feed conversion efficiencies (FCE) were similar between lambs grazing on either diversified or standard pasture. Average final lamb liveweight off diversified pasture was 4.2 kg higher than off standard pasture. The higher pre-weaning liveweight gain and subsequent greater weaning liveweight off diversified pasture was maintained throughout the summer and autumn.
Open Access
Milksolids production of dairy cows grazing lucerne and perennial ryegrass in spring
(New Zealand Society of Animal Production (Inc), 2013) Smith, G; Bryant, Racheal; Edwards, G
The potential of New Zealand grazing systems is dependant on the dry matter (DM) yield, nutritive characteristics, and utilisation of pasture. The most common pasture is a mixture of ryegrass and white clover, which is tolerant of a wide range of environments and management (Kemp et al. 1999). However species such as these with shallow root systems and poor growth in high temperatures will have reduced herbage accumulation and quality during dry summer periods (Hoglund & White 1985). As demand for irrigation has increased to alleviate these problems, it has also raised questions about water allocation impacts on dairy farm production and profit (Thorrold et al. 2004). For Canterbury, which experiences hot, dry summers, lucerne is a potential source of high quality feed due to its active warm season growth and greater water use efficiency (Mills & Moot 2010).
Open Access
Formulation of pasture seed mixtures with emphasis on the effect of nitrogen fertilisation : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2023) Myint, Thinzar Soe
The aim of this study was to determine the optimal proportions of pasture mixtures and amounts of seed and nitrogen fertiliser (N) to maximize yield and quality. Three monocultures and seven species mixtures, that differed widely in their proportions (0 to 1) of perennial ryegrass, white clover and plantain were sown at 1,000 and 2,000 viable seeds/m2 and with either 0 or 225 kg N/ha/year. Plots were drilled in 2.1 x 6 m plots on 31 March 2017 and measured for four years. The plots were grazed in common by sheep eight times annually (except the first defoliation after sowing when they were cut) and irrigated when required. Herbage accumulation and its proportions of sown species and weeds were determined at each harvest over four years (2017/2018–2020/2021); nutritive value (metabolisable energy (ME), crude protein (CP) and neutral detergent fibre (NDF)) over three years (2018/2019–2020/2021), and light interception and radiation use efficiency (RUE) over two years (2018/2019–2019/2020). To quantify the fractional intercepted radiation of pastures, an accurate method of measuring light interception was investigated. Fractional intercepted radiation was measured or predicted using a SunScan plant canopy analyser, GreenSeeker handheld sensor, rising plate meter (RPM), destructive harvests, and the combinations of SunScan and GreenSeeker, and SunScan and RPM. A hybrid method of SunScan and RPM (fractional light interception values ≤0.3 of SunScan were replaced with the predicted values using RPM) was chosen as an accurate method based on the parameters of extinction coefficient, critical LAI, R2 values, standard errors of regression. Response variables were quantified using diversity-interaction modelling to quantify effects of species ‘identity’ (monoculture performance or average monoculture performance of species in the mixtures) and ‘diversity’ (the excess of mixture performance over that expected from average performance of species in the mixtures). Seed density did not influence species identity and diversity effects on pasture yield and quality in any year. The annual total dry matter yields of ryegrass and plantain averaged over four years were 16.8 and 16.6 t DM/ha/year without N fertiliser, and 19.1 and 18.9 t DM/ha/year with N. White clover had the same production (14.9 t DM/ha/year) ± N. Mixtures produced diversity effects (additional dry matter yield). The highest extra dry matter yield (4.32 t DM/ha/year) among binary mixtures was obtained from the ryegrass-white clover mixture at the average of two N treatments. Three-species mixtures needed N to produce higher extra yield than binary mixtures. The extra benefit produced by the equal-proportional mixture of three species with N was 5.20 t DM/ha/year. The annual weed yield was lowest in perennial ryegrass (1.68 t DM/ha/year) at average N (average of 0 and 225 kg N/ha/year). The weed yield of ryegrass reduced from 2.16 at the –N level to 1.2 t DM/ha/year at the +N level. There was no N effect on weed yields of white clover and plantain. Mixtures reduced weed yield, and the highest amount of weed reduction was found in the even three-species mixtures (3.28 t/ha/year). Nutritive values were likely to be a function of identity effects and there was no effect of N. At average N, ME was higher in perennial ryegrass (11.0 MJ kg/DM) and white clover (11.0 MJ kg/DM) than in plantain (10.7 MJ kg/DM). CP was higher in white clover (25.7%) than plantain (20.5%) and perennial ryegrass (19.2%). Higher neutral detergent fibre (NDF) was found in perennial ryegrass (47.8%) than plantain (36.3%) and white clover (35.0%). After four years, an equi-proportional mixture of perennial ryegrass and white clover, based on seed count and equivalent to 12 kg PR and 7 kg WC (19 kg total coated seed)/ha at the low seed density (1000 seeds/m2), produced an optimal balance of increased total yield (20.6 t DM/ha/year), weed suppression (3% of total yield), ME (11 MJ/kg DM), CP (21.7%) and NDF (44%) at the –N level. The optimal mixture at the +N level was the three-species mixture with the proportion of 0.4 PR: 0.3 WC: 0.3 P equivalent to 9.60 kg PR, 4.20 kg WC, and 6.0 kg P (19.8 kg total coated seeds/ha) at the low seed density. It produced 23.0 t DM/ha/year with no weed, 10.8 MJ ME kg/DM, 19.5% CP, and 46.1% NDF. The equi-proportional seed mixture of perennial ryegrass and white clover changed to a mixture of 71% ryegrass, 26% white clover, and 3% weed as the actual proportions in the sward averaged over four years, yielding 20 t DM/ha/year. At the +N level, all three species mixtures, which changed to ryegrass-dominant mixtures in a four-year period, remained the highest-yielding mixtures, producing 20.8–22.4 t DM/ha/year. Differences in dry matter yield among mixtures were fully explained by the combined effect of light interception and radiation use efficiency (RUE). The optimal mixtures ±N that maximised intercepted light and RUE simultaneously were the same mixtures that produced maximum dry matter yield. They provided 188 and 170 MJ/m2/year more intercepted photosynthetically active radiation (PAR) and 0.23 g DM/MJ PAR more RUE. This study provided the two optimal seed mixtures for ±N level that maximised total dry matter yield with high quality and minimised weed yield under irrigated conditions. The dry matter yield differences among monocultures and mixtures were explained by the accumulated intercepted PAR and RUE. Moreover, there was an observation that accumulated intercepted PAR and RUE values changed depending on the methods used to measure light interception.
Open Access
On-animal sensors may predict paddock level pasture mass in rotationally grazed dairy systems
(Elsevier B.V., 2024-04) Edwards, JP; Qasim, M; Bryant, Racheal; Thomas, C; Wright-Watson, C; Zobel, G; Neal, MB; Eastwood, CR
Precision livestock farming aims to improve animal welfare and farm management using digital technology. We investigated the potential of individual on-animal sensors to predict paddock-level pasture mass, an important metric for grazing management in pasture-based dairy systems. The study consisted of four groups of 25 cows assigned to different pasture allocations (ranging from an estimated 80% to 120% of their energy requirements) over two 20-day experimental periods (late spring and late summer). Each cow was fitted with five sensors that measured a range of behaviours, including rumination time, eating/grazing time, activity and lying time. These data were used to build predictive models of pasture mass, which was estimated by calibrated rising plate meter. Our results show that rumination time was the most critical behaviour for predicting paddock-level pasture mass; the best predicted was post-grazing pasture mass (kg DM/ha) with a maximum Adjusted-R² value of 0.58 using a linear model. Including pasture and behaviour data at less than 24-hour resolution did not improve model performance, likely due to the importance of rumination, which is a diurnal behaviour. It is unclear whether this level of predictive ability is practically useful for making grazing management decisions; however, given its near real-time nature, low effort, and objectivity, the approach may provide value to farmers. Further evaluation is needed to determine how providing these data affects farmers' decision-making processes and therefore its value. In conclusion, our proof-of-concept experiment demonstrates the potential of individual on-animal sensors to predict post-grazing pasture mass, and this could help farmers make informed decisions for grazing management.
Open Access
Can the inclusion of forage chicory in the diet of lactating dairy cattle alter milk production and milk fatty acid composition? Findings of a multilevel meta analysis
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-04-01) Mangwe, MC; Bryant, Racheal; Olszewski, A; Herath, G; Al-Marashdeh, Omar
In traditional ryegrass/white clover (Lolium perenne L./Trifolium repens L.) pastoral systems, forage herbs such as chicory (Cichorium intybus L.) present an opportunity to fill feed deficits during late spring and summer. Although multiple research publications have evaluated the efficacy of chicory for enhancing milk production and milk fatty acid (FA) profile, no publication has quantitatively synthesised the body of research. This systematic review and meta-analysis examined the effect of chicory on milk production and composition, as well as on the milk fatty acid composition of dairy cattle. A total of 29 comparisons from 15 unique research publications involving 597 dairy cattle were used to develop a dataset for analysis. Three-level random-effect and robust variance estimator models were used to account for the hierarchical structure of the data and the dependency of effect sizes within publications. Chicory inclusion increased milk yield when compared to grass-based diets {weighted mean difference (WMD) = 1.07 (95% CI 0.54–1.60) kg/cow/d, p < 0.001}, but it provided a similar milk yield when compared to other forages such as legumes and herbs {dicots; WMD = −0.30, (95% CI −89–0.29) kg/cow/day, p = 0.312}. Increases in milk yield were congruent with differences in DM intake (p = 0.09) and ME intakes (p = 0.003), being similar in chicory-fed and dicot-fed cows but higher than grass-fed cows. Chicory feeding’s effect on milk solids was twice as high during mid lactation {154 days in milk; WMD = 0.13, (95% 0.081–0.175) kg/cow/day, p < 0.001} as during late lactation {219 days in milk; WMD = 0.06, (95% 0.003–0.13) kg/cow/day, p = 0.041}. In line with milk yield, greater and more significant effect sizes were found for alpha linolenic acid {ALA; WMD = 0.20 (95% CI 0.06–0.35) g/100 g FA, p = 0.011} when chicory was compared to grass species only. Comparing chicory with dicots suggests that chicory inclusion did not impact ALA concentrations {WMD = 0.001 (95% CI −0.02–0.2) g/100 g FA, p = 0.99}. There were no differences in conjugated linoleic acid concentration in the milk of cows fed chicory or control diets. The study provides empirical evidence of chicory’s efficacy for improved milk production and milk fatty acid composition.
Open Access
Ovine KRTAP36-2: A new keratin-associated protein gene related to variation in wool yield
(MDPI, 2023-11) Zhou, Huitong; Li, W; Bai, L; Wang, J; Luo, Y; Li, S; Hickford, Jonathan
Keratin-associated proteins (KAPs) are structural components of wool fibres. High-glycine/tyrosine (HGT)-KAPs are a subset of the KAP family, and their abundance in fibres varies. In this study, we report the discovery of an ovine HGT-KAP gene to which we assigned the name KRTAP36-2. Polymerase chain reaction and single-strand conformation polymorphism (PCR-SSCP) analyses revealed four variants of this gene in a screening population of 170 sheep from a variety of breeds. The DNA sequencing of the variants revealed four single-nucleotide polymorphisms (SNPs) and a dinucleotide deletion. Three of these SNPs were in the coding region, and one of these was non-synonymous and potentially led to the amino acid substitution p.Cys27Gly near the middle of the protein. The remaining SNP was located near the putative TATA box, and the di-nucleotide deletion was near the putative transcription initiation site. The effect of this variation in KRTAP36-2 was investigated in 274 Southdown × Merino lambs that were the progeny of five sires. Variation was only found to be associated with wool yield, that is, the proportion of the greasy fleece that remained as clean fleece upon scouring (expressed as a percentage). This may have some value in increasing wool production.
Open Access
Spatiotemporal expression and haplotypes identification of KRT84 gene and their association with wool traits in Gansu Alpine Fine-wool sheep
(MDPI, 2024-02) Yu, X; Li, S; Zhou, Huitong; Zhao, F; Hu, J; Wang, J; Liu, X; Li, M; Zhao, Z; Hao, Z; Shi, B; Hickford, Jonathan
Keratin (K) is a major protein component of hair and is involved in hair growth and development. In this study, we analysed the expression, localization, and polymorphism of the K84 gene (KRT84) in Gansu Alpine Fine-wool sheep using immunofluorescence, RT-qPCR, and PARMS (penta-primer amplification refractory mutation system). Haplotypes of KRT84 were also constructed and their relationship with wool traits analysed. It was revealed that KRT84 was highly expressed in hair follicles, including the inner root sheath, outer root sheath, and hair medulla and at all six lamb ages investigated from 1 to 270 days of age. Three SNPs were detected in KRT84 exon 1, and they formed three haplotypes (named H1, H2, and H3) and six genotypes. Analyses revealed an association between haplotype combinations (diplotypes) and the mean fibre curvature, mean staple length, mean staple strength, mean fibre diameter, the coefficient of variation of fibre diameter, and comfort factor for these sheep. These results suggest that KRT84 is of importance in determining several key traits in Gansu Alpine Fine-wool sheep and that the gene could possibly be used as a genetic marker for wool trait selection in these sheep.
Open Access
Screening and identification of lncRNAs in preadipocyte differentiation in sheep
(Springer Nature, 2024-03-04) Hao, Z; Jin, X; Hickford, Jonathan; Zhou, Huitong; Wang, L; Wang, J; Luo, Y; Hu, J; Liu, X; Li, S; Li, M; Shi, B; Ren, C
Studies of preadipocyte differentiation and fat deposition in sheep have mainly focused on functional genes, and with no emphasis placed on the role that long non-coding RNAs (lncRNAs) may have on the activity of those genes. Here, the expression profile of lncRNAs in ovine preadipocyte differentiation was investigated and the differentially expressed lncRNAs were screened on day 0 (D0), day 2(D2) and day 8(D8) of ovine preadipocyte differentiation, with their target genes being predicted. The competing endogenous RNA (ceRNA) regulatory network was constructed by GO and KEGG enrichment analysis for functional annotation, and some differentially expressed lncRNAs were randomly selected to verify the RNA-Seq results by RT-qPCR. In the study, a total of 2517 novel lncRNAs and 3943 known lncRNAs were identified from ovine preadipocytes at the three stages of differentiation, with the highest proportion being intergenic lncRNAs. A total of 3455 lncRNAs were expressed at all three stages of preadipocyte differentiation, while 214, 226 and 228 lncRNAs were uniquely expressed at day 0, day 2 and day 8, respectively. By comparing the expression of the lncRNAs between the three stages of differentiation stages, a total of 405, 272 and 359 differentially expressed lncRNAs were found in D0-vs-D2, D0-vs-D8, and D2-vs-D8, respectively. Functional analysis revealed that the differentially expressed lncRNAs were enriched in signaling pathways related to ovine preadipocyte differentiation, such as mitogen-activated protein kinase (MAPK) pathway, the phosphoinositide 3-kinase protein kinase B (PI3K-Akt) pathway, and the transforming growth factor beta (TGF-β) pathway. In summary, lncRNAs from preadipocytes at different stages of differentiation in sheep were identified and screened using RNA-Seq technology, and the regulatory mechanisms of lncRNAs in preadipocyte differentiation and lipid deposition were explored. This study provides a theoretical reference for revealing the roles of lncRNAs in ovine preadipocyte differentiation and also offers a theoretical basis for further understanding the regulatory mechanisms of ovine preadipocyte differentiation.

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