Pasture Growth Rates Research Articles

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.

Yield and growth rates of pastures grown in the Bay of Plenty region over 35 years

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 withprevious methods, to provide a quantified description of mean monthly pasture growth rates across the Bay of Plenty region, in New Zealand.

Plantain (Plantago lanceolata L.) content within plantain/ perennial ryegrass (Lolium perenne L.) pastures may be limited by livestock treading damage

TThere is evidence that plantain (Plantago lanceolata L.) persistence within perennial ryegrass (Lolium perenne L.) dominant dairy pastures is usually poor. One factor potentially limiting plantain content and persistence is treading damage, caused by cows grazingpasture while the soil moisture content is high. The impact of treading damage on plantain regrowth and survival was investigated in two field experiments at Massey University, Palmerston North. In a small-plot study, cow treading damage was simulated on separateplantain and perennial ryegrass pastures using a novel treading device. Subsequently, a larger-scale experiment investigated the impact of treading damage by grazing dairy cows on plantain regrowth and survival within a mixed plantain/perennial ryegrass pasture. Damage by the treading device, in late spring, immediately reduced the growth rate of both plantain and perennial ryegrasspastures by 30%, however neither plantain content nor density were reduced. In experiment 2, treading damage reduced the growth rate of the mixed pasture by 50% in early spring but it recovered during late spring. Plantain content and density were both initially reduced by the treading damage treatment but recovered to pretreading levels by autumn. These results suggest that treading damage from cows may be an important cause of reduced plantain content in dairy pastures during spring, however there was no evidence that treading damage reduced plantain persistence.

Pasture and grassland productivity and foliar elongation of wheatgrass in Southern Patagonia

The aim of this work was to show the relationship of the productivity of a pasture and grassland, the living and dead material, and the foliar elongation of wheatgrass with the soil moisture and the thermal sum in Southern Patagonia (Argentina). During the years 2015/16 (Year 1) and 2016/17 (Year 2), in closures excluded from grazing, the plant height, the accumulated aerial biomass (AAB) and the daily growth rate (DGR) of a mixed pasture and grassland were determined monthly from October to February. The forage harvested from the pasture was characterized in live (LM) and dead material (DM), and the live AAB was calculated. In selected wheatgrass plants, the leaf elongation rate (LER) was determined. Soil moisture (SM) was measured and the thermal sum (TS) was calculated. The AAB was analyzed using a factorial arrangement in a completely randomized design. The results were subjected to ANVA with repeated measures analysis and the means were adjusted with the Tukey-Kramer test. DGR, LM, and LER were related to SM and TS by multiple regression analysis. In both Year 1 and Year 2 and same months the AAB of the pasture exceeded the forage accumulated by the grassland. The LM and the LER varied according to the changes in the SM, and the TS explained the variations of the parameters described, which should be considered when developing future management strategies in this type of pasture.

Monitoring herbage mass and pasture growth rate of large grazing areas: a comparison of the correspondence, cost and reliability of indirect methods

AbstractTimely grazing decision-making requires routine information on the herbage mass (HM) and pasture growth rate (GR). The aim of this study was to compare the correspondence, cost and reliability of two indirect methods –the comparative yield method (COMPYLD) and the pasture-meter (CDAX)– to estimate HM and weekly GR of a 42 ha grazing area. Weekly assessments from April 2017 to October 2018 were made with both methods to estimate HM and GR of 13 individual paddocks. In addition, estimated GR were compared to aerial net primary productivity (ANPP) estimated using remote sensing (SAT). Estimated HM was 22% lower for COMPYLD than CDAX (HMCOMPYLD = 33 + 0.78*HMCDAX, R2 = 0.61, CV = 17%, RMSE = 291 kgDM/ha). The correspondence between methods of estimated weekly GR of individual paddocks was weak (GRCDAX = 0.18*GRCOMPYLD + 19.1, R2 = 0.05, CV = 73%, RMSE = 21.8 kgDM/ha/d). However, when integrated in three-week moving-averages, over the complete grazing area, COMPYLD and CDAX yielded similar GR up to 35 kg DM/ha/d. Accumulating GR of the grazing area over one year resulted similar to annual SAT-estimated ANPP. These results imply that, on one hand, decisions based on nominal HM, such as target HM and grazing strip size, would need to be adjusted depending on the method, but on the other hand, decisions based in temporal trends or GR, such as size and timing of set-aside areas for reserves, would be unaffected by method. Compared with COMPYLD, CDAX would be advantageous whenever high labour costs offset higher amortization, maintenance and fuel costs, provided there is an alternative in place to monitor during downtime periods.

GROWTH CURVE OF A TROPICAL MIXED-GRASS PASTURE IN A HOT AND HUMID CLIMATE

<p><strong>Background. </strong>Pasture growth rate (PGR, kg/ha/day) depends on climatic and management practices. However, studies on the influence of the environment on pasture production and productivity of dry matter are scarce in tropical, hot, and humid regions of México. <strong>Objective.</strong> To estimate the pasture growth curve using time and climatic variables. <strong>Methodology.</strong> We related, through nonlinear models, the accumulated growth of a pasture composed of native grasses mixed with exotic grasses, using time and the variables temperature and day length as independent variables, the latter integrated into a single variable called thermal photo units (PTU). We estimated the daily growth rates of five divisions; from these, the forage yields for ten days until completing 29 periods. The best-fit models had the largest coefficients of determination and the lowest Akaike’s information criterion. <strong>Results.</strong> The model that best described the relationship between cumulative yield (Y) and cumulative growing days (X) was reciprocal-quadratic: y = x/(0.097535 – 0.0000881x + 0.0000006810x<sup>2</sup>) with R<sup>2</sup><sub>Adj,</sub> of 0.9988 and an AIC<sub>C</sub> of 222.6. The model that best described the relationship between the accumulated performance and the accumulated PTU was rational: y = (- 317.8 + 1.594x + 0.00001307x<sup>2</sup>)/(1 + 0.001059x + 0.00000001964x<sup>2</sup>), with R<sup>2</sup><sub>Adjt</sub>.=0.9985 and AIC<sub>C</sub>=233.4. Likewise, a two-segment model showed a close fit. The logarithmic model described the first segment: y<sub>1</sub> = -2268 + 417.2*(ln(x)), when y<sub>2</sub> =1079.3e<sup>0.00003932X</sup>, if x > 8415; with R<sup>2</sup><sub>Adj.</sub> = 0.9975 and AICc = 245.1. The value 8415 PTU was when the first derivative of both models coincided. <strong>Implications.</strong> The information generated is useful because it allows grazing system adjustment concerning the correct stocking rate application and designing more efficient grazing rotations. <strong>Conclusions. </strong>The conversion of growth rates to accumulated yield for ten-day periods produced a smooth curve that allowed fitting high-precision nonlinear models to predict forage accumulation from time and climatic variables.</p>

Summer growth rates and annual yields of perennial ryegrass (Lolium perenne L.) in the Upper North Island are expected to decline as a result of climate change

Evaluating the ability of perennial ryegrass to continue underpinning New Zealand’s low-cost dairy production systems under future climate change scenarios requires a modelling approach. In this study, climate projections for different climate change scenarios were used in the BASGRA pasture model to predict changes in annual yields and seasonal pasture growth rate patterns of perennial ryegrass. These predictions, including uncertainty, were made for the years 2010-2014, 2040- 2044 and 2090-2094 in 14 dairy-dominant subregions in the Upper North Island of New Zealand. The suitability of perennial ryegrass is expected to decline in the future across all subregions, with worse outcomes expected under higher atmospheric greenhouse gas levels. Winter is expected to be the season least affected by climate change and summer the most affected. Late-winter/spring is predicted to become the main growing season, followed by late-autumn/early-winter. The ability offarmers to adapt their farming practices is essential in remaining profitable and internationally competitive.

Carbon cycle of native pasture-based beef cattle production systems in the Pantanal area of the Paraguayan Chaco

The objective of the present study was evaluate the carbon cycle in Paraguayan Pantanal area native grassland ecosystems by measuring pasture growth and simulating animal grazing. For this purpose, soil analyzes, annual productivity and forage quality were carried out in 4 agro ecological sites of a 20,000 ha located in Alto Paraguay Department (21º 1' 29.85”S and 58º 17' 38.55” W), from Dec 21, 2019 to Feb 12, 2020. In the selected location was installed an 8 m x 8 m exclusion cage with three treatments (4 m2 subplots), corresponding to cutting intervals (35, 70 and 105 CI days, respectively). The seasonal dry matter (DM) production and the pasture growth rate, adjusted stocking rate at three production levels (50, 70 and 75% breeding rate, respectively), carbon contained in organic matter (OM), root system and aerial biomass accumulated in ground were evaluated. The data were compared using Tukey test with a 5% probability. The emission of greenhouse gases (GG) per head and per ha was simulated and adjusted to breeding livestock to a total area of 6,600 ha and 5,000 grassland ha. The 35 days CI presented 32% higher productivity than 105 days CI in carbon sequestration. The best capture/emission balance per ha was observed in 35 days CI with the 50% breeding rate, producing 1,481 kg of CO2-e ha-1, intensifying and increasing the breeding rate to 75%, the balance decreases to 1,294 kg of CO2-e ha-1. In all cases, livestock in grassland has presented a positive balance when accounting for GG per unit area.

Survival analysis of germination data in response to temperature for Ornithopus species and other temperate pasture legumes.

Cool temperatures can limit productivity of temperate grazing systems as poor pasture growth rates in winter create feed shortages for livestock. Ornithopus spp. (serradella) are broadly adapted annual pasture legumes that produce high-quality forage in soil types considered marginal for other temperate legume species. However, serradella establishment is perceived to be difficult in cool-season environments. We used survival analysis to compare germination rate and seedling emergence for two serradella species (yellow serradella and French serradella) against three reference species (Medicago sativa, M. polymorpha and Trifolium subterraneum ) in four temperature treatments (10/5, 15/10, 20/15 and 25/20°C; max/min). We also compared shoot relative growth rate and photosynthetic rate at 15/10°C (cool) and 23/18°C (warm). Cool temperatures (10/5, 15/10°C) did not slow germination rates for serradella relative to the reference species, but warm temperatures (20/15, 25/20°C) delayed emergence and reduced post-emergent shoot growth rates. Once established, Ornithopus spp. had similar mean photosynthetic rates and stomatal conductance at cool temperatures to the reference species. We conclude that, contrary to common perception, cool temperatures did not adversely influence germination, emergence, or early growth of Ornithopus spp. relative to the reference species.

Effect of Sheep Grazing, Stocking Rates and Dolomitic Limestone Application on the Floristic Composition of a Permanent Dryland Pasture, in the Montado Agroforestry System of Southern Portugal.

Simple SummaryThe Montado is a characteristic ecosystem of the Mediterranean region, where agricultural activities, animal production and forestry coexist alongside tourism, hunting and leisure activities. Animal grazing is fundamental for the conservation of the Montado, and it is imperative to clearly understand its interactions with the pasture floristic composition (PFC) of the Montado. The objective of this study was to evaluate the effect of sheep grazing, stocking rates and dolomitic limestone application on the floristic composition of permanent dryland pastures, in the Montado agroforestry system of Southern Portugal. The type of grazing influences the PFC, which may be positively or negatively impacted, depending on the adopted system. Deferred grazing seems to benefit the disappearance of undesirable plants and the appearance of desired plants. The results of this study allow for more informed management decisions and a potential increase in animal production but also improve the knowledge of conservation strategies in the Montado.The Montado is a complex agroforestry–pastoral ecosystem due to the interactions between soil–pasture–trees–animals and climate. The typical Montado soil has an acidic pH and manganese toxicity, which affect the pasture’s productivity and pasture floristic composition (PFC). The PFC, on the other hand, can also be influenced by the type and intensity of grazing, which can lead to significant decreases in the amount of biomass produced and the biodiversity of species in the pasture. The objective of this study was to evaluate the effect of grazing type, by sheep, and different stocking rates on the PFC throughout the vegetative pasture cycle in areas with and without dolomitic limestone application. Thus, four treatments (P1UC to P4TC) were constituted: P1UC—without limestone application (U) and continuous grazing (CG); P2UD—U and deferred grazing (DG); P3TD—with the application of limestone (T) and DG; P4TC—T and CG. In DG plots, the placement and removal of the animals were carried out as a function of the average height of the pasture (placement—10 cm; removal—3 to 5 cm). The PFC was characterized in winter, at the peak of spring and in late spring. The PFC data were subjected to a multilevel pattern analysis (ISA). The combination of rainfall and temperature influenced the pasture growth rates and consequently the height of the pasture at different times of the year. Therefore, with the different growth rates of the pasture throughout the year, the sheep remain for different periods of time in the deferred grazing treatments. In the four treatments, 103 plant species were identified. The most representative botanical families in the four treatments were Asteraceae, Fabaceae and Poaceae. ISA identified 14 bioindicator species: eight for the winter period, three for the late spring vegetative period and three for the TC treatment.

The Influence of Rotational Length, along with Pre- and Post-Grazing Measures on Nutritional Composition of Pasture during Winter and Spring on New Zealand Dairy Farms.

Simple SummaryInconsistencies in the quality (nutritional composition) of pasture herbage can potentially affect the lactational performance of dairy cows. The nutritional composition of ryegrass–white clover pastures was grazed at different rotation lengths in New Zealand, on the hypothesis that longer rotations lengths would result in more mature swards, with lower quality herbage. Grazing rotation length, leaf regrowth stage at grazing, and pre-grazing DM yield during winter and spring had significant effects on the pasture herbage quality. In New Zealand, the length of the grazing rotation is adjusted based on the pasture availability, seasonal variations, and growth rate of different pastures. This information can be helpful for dairy farmers to manipulate pasture management to optimise the cows’ performance.The quality of ryegrass–clover pasture was investigated between August (winter: start of calving) and November (spring: end of breeding) on pasture-based dairy farms (>85% of total feed from pasture) that had short (n = 2, Farms A and B; winter ~30 days, spring ~20–25 days) or long (n = 2, Farms C and D; winter ~35 days, spring ~25–30 days) grazing rotations to determine whether quality was affected by grazing rotation length (RT). Weekly assessments of pasture growth and herbage quality were made using a standardised electronic rising plate meter, and near-infrared spectroscopy, respectively. Data were subjected to repeated measure mixed model analysis, in which herbage quality was the outcome variable. The highest pre-grazing dry matter (PGDM) and height, post-grazing dry matter (DM) and height, and number of live leaves per tiller (leaf regrowth stage, LS) were present in late spring. Neutral detergent fibre (NDF), acid detergent fibre (ADF), metabolisable energy (ME), and organic matter digestibility (OMD) were positively correlated to each other (r2 ≥ 0.8) whilst ADF and lipid, and ADF and OMD were negatively correlated (r2 ≥ −0.8; p < 0.01). Metabolisable energy content was negatively correlated with ADF and NDF (r2 = −0.7, −0.8, respectively), and was inversely related to PGDM. Metabolisable energy was higher (p < 0.05) in farms with shorter (overall mean: 11.2 MJ/kg DM) than longer (10.9 MJ/kg DM) RT. Crude protein was also inversely related to PGDM and was higher with shorter (23.2% DM) than longer (18.3% DM; p < 0.05) RT. Pre-grazing DM affected the amount of pasture that was grazed and, hence, the amount of DM remaining after grazing (post-grazing DM or residual), so that PGDM was correlated with post-grazing height and residual DM (r2 = 0.88 and 0.51, respectively; both p < 0.001). In conclusion, RT, LS, and PGDM during winter and spring influenced the herbage quality, therefore, better management of pastures may enhance the productivity of dairy cows.

GrasProg: Pasture Model for Predicting Daily Pasture Growth in Intensive Grassland Production Systems in Northwest Europe

Knowledge about pasture growth rates is crucial for optimizing forage use efficiencies in intensively managed pasture and silage-based dairy systems, enabling optimized cutting/grazing times for high yields with high forage quality. The aim of this study was to parameterise a simple model, GrasProg, for predicting pasture growth in an intensively managed dairy production system under a cut-and-carry management. For this, pasture crop-growth rates were measured over a period of two years (2016 and 2017) at five contrasting sites in Schleswig-Holstein, Northern Germany. The pastures received nitrogen (N) fertilizer at a rate of 280 kg N ha−1 and were cut on a four-week interval. Average annual dry matter (DM) yields ranged from 10.9 to 11.6 t/ha for the three different locations. The DM accumulation simulated by GrasProg matched actual measurements over the varying intervals well (R2 = 0.65; RMSE = 49.5 g DM m−2; and NSE = 0.44). Two model parameters were adjusted within the vegetation period, namely, the relative growth rate, a proxy of the number of generative tillers, and the initial biomass at the start of each growth period, a proxy for the tillering density. Both predicted and measured pasture growth rates showed the same typical seasonal pattern, with high growth rates in spring, followed by decreasing growth rates to the end of the vegetation period. These good calibration statistics, with adjusting of only two model parameters, for the different sites and different climatic conditions mean that GrasProg can be used to identify optimum grazing or cutting strategies, with optimal yield and forage quality.

How Does Nitrogen Application Rate Affect Plant Functional Traits and Crop Growth Rate of Perennial Ryegrass-Dominated Permanent Pastures?

High doses of nitrogen (N) fertiliser input on permanent pastures are crucial in terms of N surplus and N losses. Quantitative analyses of the response of plant functional traits (PFT) driving crop growth rate (CGR) under low N input are lacking in frequently defoliated pastures. This study aimed to understand the significance of PFTs for productivity and N uptake in permanent grasslands by measuring dynamics in tiller density (TD), tiller weight (TW), leaf weight ratio (LWR), leaf area index (LAI), specific leaf area (SLA), as well as leaf N content per unit mass (LNCm) and per unit area (LNCa) in perennial ryegrass (Lolium perenne)-dominated pastures, in a simulated rotational grazing approach over two consecutive growing seasons. Annual N application rates were 0, 140 and 280 kg N ha−1. The phenological development of perennial ryegrass was the main driver of CGR, N uptake and most PFTs. The effect of N application rate on PFTs varied during the season. N application rate showed the greatest effect on TD, LAI and, to a lesser extent, on SLA and LNCm. The results of this study highlight the importance of TD and its role in driving CGR and N uptake in frequently defoliated permanent pastures.

Long-term Central Waikato summer-autumn rainfall and pasture growth trends. Are conditions for pasture growth changing over time?

Farmers in the upper North Island are concerned about the poor productivity of their perennial ryegrass pastures beyond 3 years and suggest this is linked to a trend towards drier conditions for pasture growth during summer and autumn. To explore how conditions for pasture growth and survival have changed, trends in rainfall (measured and interpolated; c. 1954 to 2020), frequency of soil moisture deficit stress on pasture growth (1972-2020), and pasture growth rates (simulated 1977-2020, and measured c. 1979-2020) were compiled for summer-autumn months (November to April) for two Waikato locations: DairyNZ Ruakura/Scott Farm near Hamilton; and a commercial farm at Paratu Road between Morrinsville and Matamata. Significant negative linear trends were observed for interpolated rainfall (Paratu Road only), total stress days (both sites) and simulated pasture growth (both sites). No significant trend in measured pasture growth was observed for either site, suggesting adaptive management has cushioned the physical effects of harsher climatic conditions. The suite of adaptive management practices adopted on the Paratu Road farm is described. Analysis of decadal patterns indicated greater variability in rainfall in the decade 2011-2020 (coefficient of variation ranging from 32% to 36% depending on site and data source, versus ~ 22% in earlier decades) and a significantly higher number of stress days in the decade 2011-2020 compared with the 1970s and 1980s at Paratu Road. Further adaptation strategies will be needed to mitigate these most-recent trends, should they continue as predicted by climate change forecasts.

The Benefit of Hedgerow Access on the Health and Growth Rate of Pasture Raised Broiler Chickens

Pasture rearing is an increasingly common option for small farms to produce humanely raised poultry products for an expanding market, however profit margins tend to be much lower for pastured poultry producers than for those that opt for conventional indoor rearing. Research into simple methods to optimize the growth and health of pasture-raised poultry can help small farmers maximize meat yields and decrease the morbidity and mortality of their flock, ultimately leading to higher profit margins and improved animal welfare. The objective of this study was to measure how the inclusion of mature, native foliage into pastures can impact the production performance and overall health status of two different popular breeds of commercial broiler chickens; fast-growing Cornish cross and slower growing Red rangers. During the finisher phase (30–78 days old), pastured chickens were separated by breed into either a treatment population with access to a mature bordering hedgerow, or a control population without access to a hedgerow. Weekly weight gain, daily feed intake and basic hematologic values were used to evaluate differences in the production performance and health status between each population. We found that hedge access led to a significant improvement in the rate of gain of the Cornish cross without an associated increase in feed intake, suggesting that the addition of hedges can increase meat yields in fast-growing broilers without increasing feed costs. Red rangers with hedge access demonstrated an improved ability to neutralize bacterial pathogens in whole blood and a lesser degree of hemodilution compared to control populations, suggesting improved immune function and a lower degree of heat stress in these populations. We conclude that the addition of natural environmental enrichment such as mature foliage to grass pastures can lead to improved production performance in fast-growing broilers and improvements in the health and immune function of slower growing broiler chickens.

Whole-farm modelling of grazing dairy systems in Uruguay

CONTEXTModelling grazing dairy systems from the temperate hot-summer climate region of South America is challenging due to the absence of suitable whole-farm models developed or evaluated in this region. The use of whole-farm models developed in other regions represents an opportunity. However, the accuracy and precision of their predictions need to be assessed. OBJECTIVESThe present study evaluated the predictive ability of Farmax Dairy Pro, a whole-farm model developed in New Zealand, to simulate grazing dairy systems in Uruguay. METHODSData used for the model evaluation was obtained from a dairy farmlet study carried out in Uruguay. The study aimed to explore four intensification strategies based on increasing home-grown forage utilisation and milk output per hectare. The field experiment consisted of four farmlets using two feeding strategies: [Grass Maximum (GMAX) and Grass Fixed (GFIX), based on the amount of grazed herbage in the diet], and two cow genotypes [New Zealand (NZHF) or North American Holstein-Friesian (NAHF)]. The four farmlets were modelled with Farmax for two consecutive years. Model evaluation was performed using standard regression, dimensionless and error index statistics. The model was evaluated by comparing predicted versus observed monthly patterns of milk, milk fat, milk protein and milk solids (MS; milk fat + milk protein) yields, body condition score (BCS), body weight (BW), DM intake (DMI) and net pasture growth rate (PGR). An application of the model was demonstrated by modelling three scenarios for the GMAX-NZHF farmlet. RESULTS AND CONCLUSIONSThe predictive ability of Farmax was similar for the four farmlets modelled, including patterns over time, for all the variables evaluated. The model provided a robust prediction for monthly patterns of milk and milk components yields at a herd level for total DMI and PGR. The model had a moderate ability to predict monthly patterns of individual milk and milk components yields and BCS, and a poor ability to predict BW. The scenario modelling results indicate that the model could be used with confidence to simulate different farm system alternatives. Overall, the Farmax Dairy Pro model had the potential to provide adequate predictions for grazing dairy systems from Uruguay. SIGNIFICANCEThis model will allow the exploration of future intensification pathways for grazing dairy systems in Uruguay and the region, including changes in the forage sequence, stocking rate and calving season. Further adjustments of the model will expand the range of systems and latitudes for this model to be utilised.

Multipurpose simulation model for pasture-based mobile Automated Milking and Marketing System, Part-I: Pasture, milk yield, and milk marketing characteristics

It is essential to promote sustainable dairy farming which could lead to improved animal welfare, economic benefits, biodiversity and environmental benefits, milk quality, and customer satisfaction. In this regard, a mobile automated milking system (AMS) could contribute a lot. However, mobile AMS is a new innovative system which is not investigated well. Therefore, a simplified and integrated management approach should be introduced. The main objective of this study was to develop a multipurpose simulation model (DigiMilk model) specific to pasture-based mobile AMS. The model comprises five major subsystems: Pasture yield as dry matter (DM) and grazing characteristics; AMS Milking and milk yield characteristics; Milk handling and marketing; Resource consumption; and Economic assessment. This paper (Part-I) focuses on the first three components while the remaining two subsystems would be addressed in Part-II of this paper. DigiMilk model was built in MATLAB-Simulink environment. It was tested and evaluated using mainly secondary data and limited primary information acquired from a dairy farm in central Sweden. In this initial analysis, a continuous stocking system on pasture was assumed to be implemented from May 15 till September 15. Multiple sensitivity analyses were successfully conducted to get more insights. The results indicated that, considering maximum pasture growth rate of 77 kgDM day−1ha−1, the accumulated average pasture yield, over the grazing season, was estimated to be 6928 kgDM ha−1. For cows with average grazing rate of 16–18 kgDM day−1cow−1, the stocking rate of 3 cow ha−1 could lead to good performance of grazing management. When stocking rate and grazing rate of 3 cow ha−1 and 16 kgDM day−1cow−1 were considered respectively, the cumulative milk yield values (excluding amount consumed by calves) over the grazing season were estimated to be 2101 L cow−1 and 6303 L ha−1. Out of this 6303 L ha−1, 2952 L ha−1was estimated to be sold on-site, using milk vending machine (MVM), while 3351 L ha−1 was to be delivered to super market. The accuracy of results from the the simulation model could be improved with future work with more real data from actual demonstration of mobile AMS over the entire grazing season. In addition to its capacity to serve as an integrated decision making tool, DigiMilk model enables to have organized digital data that could be useful for future researches to evaluate the environmental and/or economic performances of pasture-based dairy systems with mobile AMS.