Pasture Growth Research Articles

Use of models for identification of nitrogen fertilization strategies for filling feeding gaps of cow-calf systems in the Flooding Pampas of Argentina

CONTEXTNitrogen availability is the primary limitation for the growth of tall fescue, Argentina's most widely cultivated cool-season pasture. Significant yield gaps exist in fescue pastures on commercial farms, where average annual yields are around 5 t/ha, compared to a potential yield of 10 to 15 t/ha. Nitrogen fertilization remains uncommon among cow-calf producers, highlighting the need for a deeper understanding of the complex interactions between nitrogen fertilizer management, stocking rate, and grazing management at the whole-farm level. Considering annual and inter-annual variations in pasture growth could enable regional beef producers to make more informed decisions, improving pasture yield potential, utilization, and overall farm profitability. OBJECTIVESI) to identify if N fertilization in autumn can boost pasture growth rates as reliable source of extra feed in autumn and winter, taking into account climate variability, and II) to assess how this affects farm-level productivity and profitability. METHODSAn integrated modelling approach, combining a pasture model with a farm system beef cattle model, was employed. Various N fertilizer options (specifically, 100 kg N/ha applied in either autumn or spring) were allocated to 20 % and 40 % of farm areas, across stocking rates ranging from 0.9 to 1.3 head/ha. Simulations were conducted over the long term (1993–2013), focusing on tall fescue pasture growth. Seasonal pasture growth curves were calculated for each year, with particular attention given to identifying average years as well as those with dry autumns or dry springs. RESULTS AND CONCLUSIONSIn average years, increasing the stocking rate by 44 %, from 0.9 head/ha to 1.3, led to a 34 % increase in live weight production in weaner calves and improved gross margins by 30 %. Applying 100 kg N/ha to 20 % of the cow-calf farm, either in autumn or spring, enabled a stocking rate of 1.1 head/ha (a 22 % increase), sustaining gross margins even during dry seasons. Autumn fertilization produced a substantial residual yield response, with an average increase of +1.43 tons/ha in the following spring, and finally Expanding the fertilized area from 20 % to 40 % of the farm did not provide additional economic benefits. SIGNIFICANCEThis study provides valuable, forward-looking insights into how nitrogen fertilization strategies can improve productivity and profitability of cow-calf farms in the Flooding Pampas, especially under variable seasonal climate conditions. While limitations and areas for future research are acknowledged, the findings may also offer practical guidance for boosting livestock productivity in similar environments.

A review of extended lactation in dairy cows managed in high-input and pasture-based farming systems

Traditionally the lactation cycle of a dairy cow is based around a 12-month calving interval, allowing for 10 months of lactation, followed by a 2-month dry period. This means that the cow has to conceive within 2–3 months after calving, when she is also at peak lactation and metabolically is in a negative energy balance. Such challenging physiological conditions make it challenging for the cow to conceive at this time and many modern high-producing cows fail to get pregnant within the constraints of a 12-month calving interval. In addition, many cows still produce at a high level at drying-off time, increasing the risk of intramammary infections. Therefore, delaying conception past peak production and, as a result, extending the lactation beyond 10 months may increasingly be necessary. Additionally, extended lactation (EL) may offer other advantages such as fewer calves being born and thus fewer ‘surplus’ calves needing to be culled at a young age, fewer health and welfare issues and improved environmental outcomes (i.e. less greenhouse-gas emission; less antibiotic usage) during the lifetime of the animal. Extending lactation is a straight forward management practice in high-input dairy systems where a consistent supply of feed supplements is readily available, but may be more challenging to implement in low(er)-input pasture-based systems. The latter are much more seasonal, with a 12-month calving interval allowing pasture growth and quality to match the cow’s nutritional demands; cows calve in spring when high-quality pasture is abundant and are dried-off during winter when pasture growth is more limited. In this review, we explored the impact of EL in both high-input systems and pasture-based systems. It covers the effects of EL on milk production, composition and processing, as well as on reproductive performance, health and welfare, and environmental and economic outcomes.

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

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.

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

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.

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

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.

How Long Should Grasses of South American Campos Grasslands Rest for Stockpiling Forage?

Stockpiling forage (i.e., deferring grazing) is one way to provide forage for livestock during intervals of low pasture growth, but there are trade-offs as nutrient content declines with increasing forage maturity. Phosphorous (P) concentration, crude protein (CP) content and organic matter digestibility (OMD) were evaluated in two C3 and four C4 grasses native to the South American Campos grasslands. These were: Bromus auleticus (BROAUL) and Nasella neessiana (NASNEE) as C3 grasses and Andropogon lateralis (ANDLAT), Mnesithea selloana (MNESEL), Paspalum dilatatum (PASDIL), and Paspalum notatum (PASNOT) as C4 grasses. The grasses were grown in pots during five stockpiling periods (450, 900, 1350, 1800 and 2250 degree days, approximately 20, 40, 60, 80 and 100 days). As the forage deferment increased, the nutritional value decreased more in C4 than in C3 grasses. Short rest periods (approximately 40 days) are recommended for PASDIL and MNESEL, and medium rest periods (approximately 80 days) for ANDLAT and PASNOT. However, the C3 grasses BROAU and NASNEE maintained high P and CP concentrations and may be the most appropriate option for long rest periods (≥100 days). This information is important to manage different Campos grassland communities for the optimal rest period according to the dominant species.

Evaluation of hydrochar-derived modifier and water-soluble fertilizer on saline soil improvement and pasture growth

Soil salinization poses a serious threat to crop growth. The selection of appropriate soil modifiers and water-soluble fertilizers for saline soils represents a crucial method for enhancing crop yields. The modifiers and medium-element water-soluble fertilizers were prepared using hydrochar derived from rice straw. Two distinct experiments were designed to study the effect of modifiers and water-soluble fertilizers on saline soils. The first experiment, designated as the “Soil Cultivation Experiment” , sought to investigate the impact of various modifiers on soil quality. The second experiment, designated as the “Method of Field Micro-Area Experiment”, aimed to assess the influence of water-soluble fertilizers on saline soils. The results showed that the application of modifiers and water-soluble fertilizers significantly enhanced comprehensive soil physical and chemical properties, crop growth, soil enzyme activity, and other key indicators in saline and alkaline soils. The optimal dosage of the modifier was 20 g/kg, which reduced the pH value from 8.62 to 8.21 and the decreased alkalinity by 8.26%. Furthermore, their application effectively boosted nutrient levels, including organic matter, and increased soil enzyme activity. The biomass of alfalfa showed enhancements of 63.01% and 20.87% and the biomass of leymus chinensis increased by 29.39% and 9.02% for the two batches, respectively. Notably, the application of water-soluble fertilizer yielded achieved superior results. This study also provided a theoretical basis for their future application in soda saline–alkali soil.

Changes to soil profile carbon and nutrient distribution following pasture renewal with full inversion tillage

ABSTRACT Full inversion tillage (FIT) at pasture renewal is a management option aiming to increase carbon stocks in long-term pasture, to achieve carbon neutrality. This study investigated the effects of FIT on carbon and nutrient distribution in the soil profile (0–7.5, 7.5–15, 15–22.5 and 22.5–30 cm depths) as well as nutrient uptake, and subsequent fodder crop and/or pasture yields across three pasture renewal trials (Trials 1 and 3: Alfisol; Trial 2: Andisol). These effects of FIT were assessed against standard tillage treatments (no till, shallow till), and non-renewed pasture within 8–18 months post-tillage. FIT changed soil carbon stratification, causing 16%–46% reduction in topsoil (0–7.5 cm) cation exchange capacity across the three trials. However, nutrient levels after FIT remained within recommended ranges for crop and/or pasture growth, avoiding any yield reductions. Topsoil fertility post-FIT depended on original degree of nutrient stratification in the soil profile. At Trial 1, temporary deficiencies caused by low subsoil P and K soil tests pre-FIT were anticipated and corrected with fertiliser nutrients for the following break crop and resown pasture. We conclude that soil testing the cultivation depth prior to FIT at pasture renewal provides the necessary soil test information to manage yield expectations.

Examining across year genotype by environment interactions for production and reproduction traits in Merino sheep

Variation in feed resource availability within production systems can cause genotype by environment interactions that change the ranking of the best animals to select between environments. Mediterranean environments have high variation in pasture growth between years that could cause genetic by environment interactions for sheep production traits. Therefore, we estimated heritabilities for live weight, fleece weight, fibre diameter and number of lambs weaned in six years from 2000 to 2005 and correlations between years comparing multivariate analysis and random regression analysis. We compared 3 methods: 1 multivariate analysis estimating (co)variances for traits in each year, 2 Random regression estimated (co)variances for intercept and slope for traits as repeated measurements fitted against average pasture growth in each year and 3. Random regression fitted against corrected average performance of animals in each year. Random regression was estimated with an order of polynomial of one for additive genetic variance and zero for permanent environmental effects. This combination of polynomials was the best fit based on Bayesian information criterion. We estimated heritabilities for each year and correlations between years using records from 3299 pedigreed Merino ewes managed at Katanning in Western Australia. There were 4651 records for adult live weight, 6750 for adult clean fleece weight, 6965 for adult fibre diameter, and 7774 for number of lambs weaned across all 6 years. Number of lambs weaned had more genotype by environment interactions than other traits, with fibre diameter and fleece weight having genotype by environment interactions between only a few years. Based on Bayesian information criterion values, multivariate analysis fit the data better for live weight, fleece weight and fibre diameter. Additionally, random regression estimated higher genetic correlations between years than multivariate analysis suggesting there was not enough flexibility in the random regression analysis, which used only first order polynomials, to fit differences between years. Pasture growth across years did not explain differences in performance for traits across years. Therefore, for number of lambs weaned, random regression using corrected average performance was a better fit than average pasture growth. For other traits, more years or a better indicator of variation in performance within and between years are required to use random regression for genotype by environment interactions.

A short-term effect of multi-species pastures and the plant’s physiological response on pasture growth

Multi-species pastures that include species with dissimilar physiological responses to water restriction (i.e., dehydration avoidance) and species that have a greater soil water access (i.e., deep-rooted species), can buffer the reduction in summer growth experienced by more shallow-rooted species and can out-yield pastures with less capacity to access soil water. The aim of the present study was to evaluate the performance of multi-species pastures comprising both deep-rooted and shallow-rooted species, under grazing by sheep, in relation to pasture growth, the seasonal changes in pasture botanical composition, and the plants’ physiological responses to field conditions across the year. The evaluated pastures were: Bromus valdivianus (Bv); Lolium perenne + Trifolium repens (Lp); Plantago lanceolata (Pl); B. valdivianus + L. perenne + T. repens (grass mixture pasture, GM); and B. valdivianus + L. perenne + T. repens + P. lanceolata (complex mixture pasture, CM). Herbage mass, net photosynthesis, leaf water relations and soil water content (SWC) at 10, 40 and 70 cm soil depths were evaluated. The SWC fluctuation through the year was related to rainfall within each season, and differences between the treatments were taken as an indirect indicator of soil water access and soil water uptake by the roots. During the soil water restriction period, mixed pastures based on species that differed in their soil water access buffered the reduced growth rate of the sensitive species, due to a decrease in competition for water uptake within the deeper soil layer (CM pasture). A shift of dominance between species, as measured in the CM pasture, buffered the reduction in pasture growth rate seen in the monocultures. The Bv pasture, which is tolerant of water restriction, had a similar annual yield to the multi-species pastures (both GM and CM). The present study highlighted the capacity of the deep-rooted species (B. valdivianus and P. lanceolata) to avoid periods of soil water restriction by extracting water from deeper soil layers.

A review of grass species yields and growth rates in Northland, New Zealand

ABSTRACT 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.

Effects of 2 wintering practices on behavioral and physiological indicators of welfare of nonlactating, pregnant dairy cattle in a pasture-based system

In countries with pasture-based dairy systems and relatively cold winters, such as New Zealand, it is common to manage pregnant, nonlactating cows on forage crop paddocks rather than pasture, due to slow pasture growth rates. Wintering dairy cattle on grazed crops can compromise welfare if wet and muddy underfoot conditions occur, which can reduce lying. This study investigated behavioral and physiological indicators of welfare of cows under 2 wintering practices: cows managed on and grazed kale crop (Brassica oleracea), and cows managed on pasture with baled hay. Following dry-off (d 0), 80 cows were randomly assigned to 1 of the 2 wintering practices (40 cows/practice) and monitored between d 4 and 32 (phase 1). During this period, lying and stepping behavior was continuously recorded using leg-based accelerometers. Blood samples were obtained at d 0 and 32 for measurements of thyroxine (T4), nonesterified fatty acids (NEFA), white blood cells (WBC), and red blood cells. All data for phase 1 were presented descriptively due to the lack of treatment replication. Daily mean air temperature during this period was 5.2°C (range: 0.0-10.7°C), and rainfall was 1.1 mm/d (range: 0-5.6mm/d). Between d 4 and 32, cows in both groups spent similar amounts of time lying (pasture with hay cows: 8.9 h/24 h ± 2.57, kale crop cows: 8.7 h/24 h ± 3.06, mean ± SEM). Both groups reduced their lying on wet and cold days, and there was evidence of rebound lying once unfavorable weather conditions stopped. Cows on kale crop had numerically higher NEFA and lower WBC compared with cows managed on pasture, although most physiological values were within normal ranges. In a second phase of the study (d 34 and 35), cows were managed under controlled, replicated conditions in the 2 wintering practices using typical on-farm stocking rates (2 or 4 cows per group in the pasture with hay and kale crop treatments, respectively; n = 10 groups/treatment). During this period, cow behavior, skin and surface temperatures, hygiene scores, feed intakes, and ground conditions were measured. Weather conditions during the 48-h exposure were mostly cold and dry (mean air temperature: 7.8°C, range: -2.2 to 20.5°C). Cows managed on pasture with hay spent more time lying down on the first day of exposure; however, this was likely due to less space being available to kale cows on this day. Cows managed on pasture with hay ruminated more than cows on kale crop on both days of observations (d 1: 37.9% vs. 30.9% of observations, d 2: 36.8% vs. 28.7% of observations for pasture with hay and kale crop groups, respectively) and were lying more often in postures indicative of greater thermal comfort. Cows managed on pasture with hay had higher skin and surface temperatures compared with cows on kale crop, whereas cows on kale crop had dirtier coats. Results suggest that opportunities for thermal comfort were greater for cows managed on pasture with hay bales, which may be due to increased rumination activities and more insulated lying areas.

Long-term evaluation of pasture production, seasonality, and variability: An application of the DairyMod pasture model for three tropical species

Adoption of improved pastures coupled with intensified management provide quality pastures in adequate quantities and thus improve livestock productivity. While pasture modelling is imperative for exploring the performance of newer pastures, models are little used for long-term simulations of multiple tropical pastures (genotype), under varying soil, climate (environment) and pasture production systems (management). We applied the DairyMod, a biophysical model to simulate the long-term pasture production of Brachiaria ruziziensis x B. decumbens x B. brizantha ‘Brachiaria Mulato II’ (BM), Megathyrsus maximus ‘Gatton Panic’ (GP), and Chloris gayana ‘Rhodes grass cv. Reclaimer’ (RR) across major dairying regions of Sri Lanka under different management scenarios and characterize the long-term pasture growth, seasonality and spatial variability, and possible implications for dairying in Sri Lanka. Simulations of three pasture species were carried out for 16 locations (8 dry (DZ), 5 intermediate (IZ), and 3 wet zone (WZ)) over 30 years (1980–2010). Three pasture management scenarios simulated were; 1) potential pasture production system under non-limiting N and irrigation (Yp) 2) rainfed pasture production system under non-limiting N fertilizer (Yw), and 3) rainfed pasture production system under current nitrogen (N) fertilizer rate (Ya). Statistical techniques were used to identify the long-term growth rates, variability, and trends in pasture production. The long-term pasture production varied greatly among climate, species, and management scenarios. Overall, the Ya showed a seasonal cycle following the rainfall pattern, with a reduction in growth rates in dry seasons (May–September). Pasture growth rates were greater in GP at Ya, and BM at Yw and Yp while RR showed the lowest growth rate at all times. Variability of pasture growth was high in DZ (May–September) and RR has the lowest growth variability. The Yw increased the growth rate (doubled) while the Yp substantially increased (nearly tripled) the growth rate and growth pattern producing less variable pastures. Simulated growth rates suggest that GP in low-input and BM in high-input farming areas would be more suitable. Our study suggested that the BM, GP, and RR are edaphic-climatologically fit for major dairying regions in Sri Lanka and the appropriate fertilizer and irrigation management can greatly increase the herbage accumulation and availability of year-round pastures. While this study offers valuable insights, the species-specific growth pattern, growth variability, yield potential under different managements and the possible implications for herbage quality need to be sensibly considered when selecting the appropriate species.

Impact of energy-mineral supplementation on the performance of young bulls from varied genetic groups during the pasture growth phase and in subsequent feedlot evaluation

ABSTRACT The aim of this study was to evaluate the performance of young bulls from different genetic groups supplemented on pasture, and to assess the residual effect of supplementation during the feedlot phase. The experiment was divided into two stages, where young bulls received pasture supplementation during the rainy season (mineral and mineral-energetic), and subsequently, were sent to the feedlot. For this purpose, three genetic groups were tested (Nelore, ½Canchim½Nelore, ½Brangus½Nelore), along with two supplementation strategies (mineral and mineral-energetic). The animals during the rearing phase had access to Cynodon spp. cv. Tifton 85 pasture, being managed under the intermittent grazing method. The ½Brangus½Nelore animals exhibited higher weights at the beginning and end of the feedlot period. Regarding the average daily gain, no differences were observed between the supplementation strategies, resulting in an average value of 1.58 kg day−1. Animals treated with mineral supplement during rearing showed an increase of 11.89% in dry matter intake for ½Brangus½Nelore, while for ½Canchim½Nelore animals, this supplementation strategy resulted in increases of 5.38%. The ½Brangus½Nelore animals showed higher initial and final weights in the feedlot. While the supplementation strategy does not impact the performance of the animals in the final phase of the production cycle.

Modelling the effects of potential climate change on the dynamics of multi-species mountain pastures: A case study in Gran Paradiso National Park, Italy

CONTEXTPasture dynamics of Alpine areas are linked to the complex cryospheric hydrology of Alpine catchment and to the interspecies competition, which are in turn expected to change remarkably under prospective global warming scenarios. OBJECTIVEThis study aimed at assessing the impact of climate change on the productivity of mountain pastures in the Gran Paradiso National Park (Italy). METHODSThe hydrological model Poli-Hydro was used, coupled with the Poli-Pasture model, able to simulate pasture growth, which was further integrated with CoSMo model to consider interspecific competition. Two (competing) species were chosen for low altitude LowAlt areas (below 1800 m asl), Trifolium alpinum and Dactylis glomerata, and two for high altitude HighAlt areas (above 1800 m asl), Festuca rubra and Nardus stricta. Model tuning and evaluation were performed against estimates of leaf area index (LAI), derived from satellite imagery during 2005–2019. Then, climate change impacts were projected until 2100 by considering four IPCC AR6 scenarios and six GCMs. Target variables included a set of agroclimatic indices, LAI and pasture yield. RESULTS AND CONCLUSIONSDue to the projected increase in temperatures during the XXI century, a measurable potential increase in productivity would be expected, especially in the highest areas (up to +97% by 2050, and + 123% by 2100 for the SSP5–8.5 scenario). The relative abundance of pasture species appears to remain mostly stable; at most, the species with higher fodder value even increases slightly. This suggests that a loss in the overall quality of biomass should not occur. These results provide preliminary evidence for the potential development of livestock farming, and thus of a relevant part of the economy in the valleys, at higher altitudes than now. However, to a certain extent pasture performance could be threatened by the projected reduction in summer rainfall, and possibly spreading of pests with increasing temperature. SIGNIFICANCEThe results obtained here could be useful for policy makers, and scientists in the field of pasture/grasslands management, to depict scenarios of future productivity, and to support redefinition of periods, and areas designated for grazing activities in the mountains.

The Season and Decade of Birth Affect Dairy Cow Longevity

Dairy cow longevity is associated with three key areas: animal welfare, the economy, and the environment. In pastoral dairy systems, cows are exposed to environmental hardships and variations in feed supply associated with the seasonal growth of pastures. The objectives of this study were to generate base parameters for longevity and evaluate the effect of season and decade of birth on herd life (HL) and length of productive life (LPL) for dairy cows in pasture-based production. Records from the Dairy Herd Improvement Database at the Instituto Nacional para el Control y Mejoramiento Lechero (Uruguay) were extracted. The dataset contained 313,146 cows born between 1 January 2000 and 31 December 2019, classified by decade and season of birth. HL and LPL were calculated for each cow. The effects of season of birth, decade of birth, and the interaction between them on HL and LPL were evaluated using a generalized mixed model. The mean HL was 73.4 and mean LPL was 42.0 months. Cows born in spring had longer LPL and HL (p < 0.001). Cows born in the 2010s had significantly shorter HL (12.8 months) and LPL (9.14 months) (p < 0.001). In conclusion, the season and decade of birth have an impact on the longevity of cows in pastoral-based systems. This study is the first to demonstrate the effect of season of birth on long-term longevity.

Grazing behavior of dairy cows under contrasting pasture allocation frequencies and areas

This study aimed to compare grazing behavior of dairy cows with highly contrasting pasture allocation frequencies. The study ran from September 9, 2022, to December 2, 2022 (12 wk), during a time when daily pasture growth was expected to exceed daily herd intake. Three pasture allocation frequencies were compared, each with 11 spring-calving cows grazing a 4-ha farmlet. The allocations were high frequency rotational grazing (HFRG; 32.5 m2/cow per allocation and 4 allocations/d), rotational grazing with weekly allocations (7RG; 909 m2/cow per allocation and each allocated area continuously grazed over 7 d), and continuous grazing (CG; 1,818 m2/cow per allocation). Animal behavior was monitored using IceQube accelerometers (Peacock Technology) and CowManager ear tags (Agis Automatisering BV). Milk yield and composition were measured and pasture cover was estimated. Daily eating time was highest for CG animals, whereas lying time, lying bouts, and ruminating time were lowest, with no differences between HFRG and 7RG. There were no differences in fat- and protein-corrected milk yield between farmlets; however, estimated accumulated pasture yield was greater with more frequent allocations. Although milk production did not differ between treatment groups, this appeared to be achieved through greater eating times when allocated pasture less frequently, at the expense of time spent lying.

The distance from tree legumes in silvopastoral systems modifies the litter in grass-composed pastures

AbstractThe use of silvopastoral systems with tree legumes is a viable alternative to recover and develop pastures, as they add N to the system influencing pasture growth. This study hypothesized that the herbage and litter of signalgrass (Urochloa decumbens Stapf) is affected by legume trees in the pasture. Treatments were composed of (1) signalgrass + Mimosa caesalpiniifolia Benth.; (2) signalgrass + Gliricidia sepium Jacq.; and (3) signalgrass monoculture. The 3-year experiment followed a randomized complete block design with three replications. Tree legumes were planted in double rows (15 × 1 × 0.5 m), in 1 ha paddocks. Litter samples were taken in five distance points (0, 1.8, 3.7, 5.6 and 7.5 m) perpendicular to tree legume rows. Signalgrass was taller at longer distances from the trees (P < 0.05). Signalgrass height differed between treatments, with taller signalgrass found in pastures mixed with G. sepium (15.6 cm) compared to M. caesalpiniifolia (9 cm) (P < 0.05). Herbage N content decreased with increasing distance from tree rows (P < 0.05). Litter N content followed a similar pattern, ranging from 23 g/kg under the trees to 12 g/kg at 7.5 m away from tree rows. Signalgrass did not grow under the tree crown (0–1.8 m), especially when intercropped with M. caesalpiniifolia. The findings of this study suggest that the type of legume trees used in the silvopastoral system has the potential to modify the pattern of grass growth and content of N in pasture litter.

Native establishment improved and weed competition reduced by topsoil removal in direct‐sown native grasslands

SummaryAustralian temperate grasslands are among its most threatened plant communities. In agricultural landscapes, major barriers to their recovery are high soil nutrient levels that favour the growth of exotic pasture and other non‐native species, high standing weed biomass creating fierce aboveground competition, and rich weed seed and bud banks providing dense emergent seedling competition. Therefore, the return of grasslands to arable landscapes through restoration must rely on overcoming these challenges, ideally by reducing soil nutrients and mitigating the effects of weeds. This study demonstrates the effectiveness of topsoil removal for restoring diverse native grassy communities by direct seeding on sites with a legacy of elevated soil nutrients and competitive exotic vegetation. Conversely, it showed that repeated shallow cultivation (four times over 12 months) to stimulate weed emergence, followed each time by herbicide application, failed to achieve this outcome, at least in the short term (three years). Grassy community restoration is imperative in Australia, but importantly, it must utilise restoration protocols that are as effective as possible so that limited time, money, and resources are not wasted. In this light, the technique of topsoil manipulation may take us one step closer to achieving this goal in agricultural locations, where their loss is most pronounced.

Impacts of environmental feedbacks on the production of a Central Queensland beef enterprise in a future climate

CONTEXTUnderstanding climate change impacts on beef production enterprises in northern Australia is challenging due to the complexity of the system, which involves biophysical processes such as pasture and animal production, herd management, economics, emissions, and the interaction among these things. Modelling is a powerful tool to help the beef industry understand the impacts of climate change and to develop adaptation plans to help ensure enterprises remain economically viable over the long term. OBJECTIVEWe assess climate change impacts on a single specialised beef enterprise south-east of Moura (24.59°S, 150.09°E) in northern Australia's Central Queensland region. This is achieved by comparing enterprise performances during a 2030s climate and a 1975–2013 baseline period. METHODSWe used a calibrated pasture model called GRASP to simulate the farm's pasture growth under multiple scenarios for land conditions, grass basal areas and stocking rates for the baseline and 2030s climates and to construct pasture growth databases – known as datacubes. The datacubes provide a simplified representation of mean coupling between the herd dynamics and livestock production model (Crop Livestock Enterprise Model). The coupled whole-of-farm model was parameterised using enterprise data collected through interviews with the property owner and allowed for feedback between the pasture and livestock systems. The feedback capability allowed us to consider changes in land condition through stocking rates and their effect on pasture growth, animal weight gain, profit and CO2 emissions. RESULTS AND CONCLUSIONSWe found that warmer and drier climatic conditions during 2030s will reduce pasture growth in austral spring and summer but increase pasture growth in winter and autumn. Increased pasture growth in winter and autumn cannot compensate for the reduction in pasture growth in the warm seasons but can improve animal liveweight gain in winter and early spring. This leads to an overall increase in annual weight gain of steers (the cattle class that provides the main income source for this farm) while the CO2 emission intensity remains similar to the baseline period. Maintaining land condition under the 2030s climatic conditions considered will require a reduction in sustainable herd size, leading to lower beef production and lower profit under current pasture and herd management strategies. Impacts will likely differ from those described if a drier future is not realised. SIGNIFICANCEThis study provides a climate change impact assessment on a specialised beef enterprise (i) being distilled from individual ruminants, and (ii) considering environmental feedbacks in the interaction between pasture and livestock systems.