Individual Paddocks Research Articles

Hepatogenic photosensitization in lambs supplemented with different levels of extruded urea in Brachiaria spp. pastures in the Brazilian Cerrado: Case report

The aim was to report cases and risk factors for hepatogenous photosensitization in lambs kept on Brachiaria spp. pastures and supplemented with levels of extruded urea (EU). The herd consisted of 69 Texel crossbred lambs with known parentage (fathers and mothers adapted to the consumption of forage of the genus Brachiaria), randomly divided into 5 groups and distributed in individual paddocks for each group. The animals were supplemented with increasing levels of EU (Amireia® 200S): 0, 6, 12, 18, and 24 g of EU per 100 kg−1 of body weight (BW). The concentration of protodioscin was estimated in the mixed pastures of Brachiaria spp. (cv. Marandu and cv. Basilisk), structural components (leaf, stem, and dead material), samples of each cultivar, and in the months of December (2018), February, and April (2019). The animals were examined daily, and when behavioral changes were identified, they underwent clinical examinations and anamnesis. Weighing was performed every 14 days, followed by necropsy and serum biochemical analysis, including gamma-glutamyltransferase (GGT). The highest concentrations of protodioscin (p < 0.0001) were found in the pastures used by animals supplemented without extruded urea (7.07 ± 0.56), in the Basilisk cultivar (11.35 ± 0.06), in the leaf blade components (2.08 ± 0.05), and thatch (2.20 ± 0.00), and in the month of April (7.34 ± 0.29) (the month with the lowest rainfall), respectively. Fourteen (20.29%) cases of photosensitization were observed in lambs, of which six recovered, and eight died. Serum GGT levels ranged from 42.2 to 225 IU/L; however, in animals that died, values ranged from 209.4 to 225 IU/L. The use of levels 12 g and 18 g per 100 kg−1 of body weight of extruded urea may contribute to the lower occurrence of photosensitization, as the animals selected pastures with lower protodioscin content, presenting a smaller number of cases.

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.

Utilising commercial farm grass growth data to evaluate long-term dry matter production of perennial ryegrass varieties

Little data are currently available on either the dry matter (DM) production of perennial ryegrass (PRG) swards as they age beyond 5 yr (i.e. permanent pasture) or the performance of PRG varieties on commercial grassland farms. Previous work has generally assumed a connection between DM production and ground score (GS) and this link has been used as a proxy for variety persistence. The evolution of technology in the form of PastureBase Ireland has led to agronomic data of individual paddocks being made available for analysis over multiple years which has allowed the long-term assessment of varieties sown as monocultures on commercial farms. This technology allowed for the inclusion of eight PRG varieties sown in 649 paddocks across 101 farms in Ireland in the current analysis. The results show little association between GS and variety DM production as varieties age to 7 yr. Dry matter production of 1- to 4-yr-old swards appeared to provide a strong indication of variety DM production in years 5–7 post-sowing (r = 0.72, P &lt; 0.05). The interaction of variety and sward age was not associated with DM production. Generally, varieties which produced the most DM in younger swards also produced the most DM in permanent pasture swards. Over longer-term periods these variety differences can manifest into large differences in DM produced and consumed on farm. The current analysis suggests that the long-term production benefits of utilising improved PRG varieties in pasture reseeding may be underestimated.

Spatial and Temporal Biomass and Growth for Grain Crops Using NDVI Time Series

Remote sensing from optical radiometers in space offers a nondestructive approach to estimating above ground biomass (AGB) with high spatial and temporal resolution, but the application is challenged by cloud cover and differences in soil background and crop phenology. We present a framework based on Sentinel-2 imagery for relating the adjusted summed NDVI measurements to the AGB. The resulting R2 values for the measured and estimated AGB ranged from 0.79 to 0.98 for individual paddocks, and the R2 from a pooled dataset (multiple crops, years, and locations) was 0.86. Application of the pooled dataset model to a separate validation dataset resulted in an R2 of 0.88; however, there was a bias that resulted in the underestimation of the measured biomass. Analysis of the impacts of the gaps in the time series showed a decrease of 0.43% per gap day for the summed NDVI values. To address the impacts of clouds, we demonstrate the use of active optical and additional satellite imagery to fill the gaps due to clouds in the Sentinel-2 imagery. The framework presented results of the spatial daily estimates of the AGB and crop growth rates.

Taking into account terrain slopes when constructing optimized trajectories of agricultural machinery

The process of optimizing the trajectories of soil cultivation and forage harvesting equipment across the field should, as much as possible, take into account and adapt to the features of the field relief. Moreover, a number of technological operations generally cannot be carried out without taking into account the slopes of the terrain, since the process may run counter to agrotechnical requirements. The analysis of various approaches to accounting for the relief, the cultivated agricultural landscape, made it possible to generalize the most important features that have reserves for optimization. Algorithms have been developed that, taking into account the magnitude of the slopes in a given field, determine the trajectories of the vehicle and optimize the time and fuel consumption. The construction of tracks for single work, group work on individual paddocks, group work by a link, incl. on the paddocks.

Evaluation of Random Forests (RF) for Regional and Local-Scale Wheat Yield Prediction in Southeast Australia.

Wheat accounts for more than 50% of Australia’s total grain production. The capability to generate accurate in-season yield predictions is important across all components of the agricultural value chain. The literature on wheat yield prediction has motivated the need for more novel works evaluating machine learning techniques such as random forests (RF) at multiple scales. This research applied a Random Forest Regression (RFR) technique to build regional and local-scale yield prediction models at the pixel level for three southeast Australian wheat-growing paddocks, each located in Victoria (VIC), New South Wales (NSW) and South Australia (SA) using 2018 yield maps from data supplied by collaborating farmers. Time-series Normalized Difference Vegetation Index (NDVI) data derived from Planet’s high spatio-temporal resolution imagery, meteorological variables and yield data were used to train, test and validate the models at pixel level using Python libraries for (a) regional-scale three-paddock composite and (b) individual paddocks. The composite region-wide RF model prediction for the three paddocks performed well (R2 = 0.86, RMSE = 0.18 t ha−1). RF models for individual paddocks in VIC (R2 = 0.89, RMSE = 0.15 t ha−1) and NSW (R2 = 0.87, RMSE = 0.07 t ha−1) performed well, but moderate performance was seen for SA (R2 = 0.45, RMSE = 0.25 t ha−1). Generally, high values were underpredicted and low values overpredicted. This study demonstrated the feasibility of applying RF modeling on satellite imagery and yielded ‘big data’ for regional as well as local-scale yield prediction.

PSX-B-9 Effect of trace mineral sources in the supplement for grazing cattle on ruminal bacteria diversity

Abstract The rumen soluble Cu and Zn can affect the rumen microbial populations. This study aimed to evaluate the effect of trace mineral sources (Cu and Zn) in the supplement of grazing steers on ruminal bacteria diversity. Eight rumen cannulated Nellore steers (541 kg ± 18 kg BW) were distributed in a randomized block design in individual paddocks of Urochloa brizantha cv. Marandu. Steers were supplemented during 101 days between dry to rainy season at 5 g/kg BW with commercial supplement (25% CP) containing Cu (40 mg/ kg) and Zn (148 mg/kg) in the inorganic (Control) or hydroxy (HDX; Micronutrients Inc., IN) source. Samples of ruminal content were collected before supplementation at day 97 of experimental period and the total DNA extracted by commercial kit (Quick-DNA Fecal/Soil Microbe Miniprep). The V3/V4 regions of 16SrRNA gene was sequencing using the Illumina MiSeq, using the Quantitative Insights into Microbial Ecology (QIIME v.1.9.1) to filter reads and determine Operational Taxonomic Units (OTUs). Data were compared using an unpaired Wilcoxon test in R. A total of 293 OTUs were identified at genus level. The HDX resulted in a higher ruminal abundance of Corynebacterium 1 (P = 0.01), Prevotella 1 (P = 0.01), Lachnoclostridium 10 (P = 0.02), Lachnospiraceae AC2044 group (P = 0.03), Lachnospiraceae UCG-008 (P = 0.03), Streptococcus (P = 0.02), Ruminococcaceae UCG-010 (P = 0.01), Ruminococcaceae UCG-014 (P = 0.01), Ruminococcus 1 (P = 0.04), Coprococcus 1 (P = 0.04), Mogibacterium (P = 0.02), Selenomonas 1 (P = 0.02), Anaerovibrio (P = 0.03), Methylobacterium (P = 0.02), Treponema 2 (P = 0.02), Rikenellaceae RC9 gut group (P = 0.03), Ruminococcaceae; uncultured rumen bacterium (P = 0.02) and Eubacterium hallii group (P = 0.05), and lower abundance of Fibrobacter (P = 0.04), Butyrivibrio 2 (P = 0.05), Anaerotruncus (P = 0.03), Ruminiclostridium 5 (P = 0.03), Anaerorhabdus furcosa group (P = 0.02) and Erysipelotrichaceae UCG-004 (P = 0.01). The use of HDX in the supplement for grazing cattle between dry to rainy season increase the ruminal abundance of bacteria, mainly into Firmicutes phylum with important structural and non-structural carbohydrates degradation functions.

Agronomic performance of ten perennial ryegrass varieties on commercial grassland farms

AbstractLittle information is available on the phenotypic performance of perennial ryegrass varieties when exposed to grazing conditions on commercial grassland farms. Grass varieties are classically evaluated in mechanically defoliated plot systems which, although designed to mimic grazing conditions, do not fully capture the range of stresses or interactions that a sward is subjected to under commercial settings or over any period longer than 4 years. The evolution of technology in the form of PastureBase Ireland has led to agronomic data of individual paddocks being made available for analysis over multiple years. Data used in the current study consisted of dry matter (DM) production and ground score data across a 7-year period from ten perennial ryegrass varieties grown as monocultures in 559 paddocks on 98 commercial farms. The results demonstrated how perennial ryegrass variety is associated with a range of agronomic performance traits on commercial farms; including total and seasonal DM production, grazing DM production and number of grazing events. Varieties with the highest total DM production also had the highest spring and mid-season DM production; autumn DM production was associated with the interaction between variety and year. The highest producing variety in the study, AberGain, produced 1342 kg DM/ha/year more than the mean of all other varieties. Variety differences manifested themselves as swards aged, with some varieties increasing in total DM production while others reduced in total DM production. The current work provides a basis for the consideration of on-farm variety assessment in the composition of future variety evaluation protocols.

Soil greenhouse gas emissions and grazing management in northern temperate grasslands

Adaptive multi-paddock (AMP) grazing, a grazing system in which individual paddocks are grazed for a short duration at a high stock density and followed by a long rest period, is claimed to be an effective tool to sustainably manage and improve grasslands and enhance their ecosystem services. However, whether AMP grazing is superior to conventional grazing (n-AMP) in reducing soil greenhouse gas (GHG) emissions is unclear. Here, we measured CO2, CH4, and N2O fluxes between August 2017 and August 2019 in 12 pairs of AMP vs. n-AMP ranches distributed across an agro-climatic gradient in Alberta, Canada. We found that field GHG fluxes did not differ between AMP and n-AMP grazing systems, but instead were regulated by specific management attributes, environmental conditions, and soil properties, including cattle stocking rate, cultivation history, soil moisture content, and soil bulk density. Specifically, we found that seasonal mean CO2 emissions increased with increasing cattle stocking rates, while CH4 uptake was lower in grasslands with a history of cultivation. Seasonal mean CO2 emissions increased while CH4 uptake decreased with increasing soil moisture content. In addition, CH4 uptake decreased with increasing soil bulk density. Observed N2O emissions were poorly predicted by the management, environmental conditions, and soil properties investigated in our study. We conclude that AMP grazing does not have an advantage over n-AMP grazing in reducing GHG fluxes from grasslands. Future efforts to develop optimal management strategies (e.g., the use of sustainable stocking rates and avoided cultivation) that reduce GHG emissions should also consider the environmental conditions and soil properties unique to every grassland ecosystem.

A referencing system to analyse performances of French organic rabbit farms

A referencing system to collect and analyse the performance of French organic rabbit farms was created using an Excel application. Reproduction data were compiled for six farms over 3 years of production (2015–2017). Does were housed in movable cages on pasture or in individual paddocks, and the livestock size averaged 33 does and varied largely according to the farm (from 8 to 62). The productive time of a doe averaged 374 days and was highly variable (75%). Female mortality averaged 17% over the period, while culling reached 10%. With 4.8 matings, 2.7 parturitions per female/year were obtained (60% fertility rate), yielding a total of 21.6 rabbits born alive and 16.7 weaned (26% mortality from birth to weaning). The yearly turnover of a full-time rabbit farmer (80 females) would potentially be around 26.3 k€/year. The database is expanding to a larger number of farms owing to the deployment of a smartphone application (GAELA). It enables management assistance for the rabbit farms and performance collection synchronized with a national secured database.

Catchment-scale 3D mapping of depth to soil sodicity constraints through combining public and on-farm soil databases – A potential tool for on-farm management

There has been much recent effort in creating digital soil maps across large areas, but these products are rarely used by farmers and those managing the land. This is due to a variety of reasons; few maps represent soil properties of agronomic relevance, the spatial resolution and depth intervals are often too coarse, and there is limited confidence in the quality of the predicted maps. This study attempted to overcome these pitfalls by creating maps of the depth to a soil sodicity constraint across the Namoi River Catchment, a 42,000 km2 area in eastern Australia. The maps were produced at a fine vertical support (1 cm) and horizontal resolution (30 m) using a single random forest model to a depth of 100 cm. Different exchangeable sodium percentage (ESP) thresholds of 6%, 10% and 15% were explored to define a constraint. Various publicly available spatial datasets were used as covariates, including satellite imagery, terrain attributes, climate, and geophysical data. The soil data used for modelling were collated from a national soil database, various soil surveys, as well as data collected on case study farms. The model could predict soil ESP across the catchment with a Lin’s concordance correlation coefficient (LCCC) of 0.56 when tested with 10-fold cross-validation based on whole-profiles. The value of including soil data collected on-farm with regional databases was clearly demonstrated to produce maps for an individual farm, resulting in considerable improvements in model prediction accuracy. The utility of the maps for farm management was assessed by comparing with cotton and grain crop yield maps for individual paddocks on case study farms. The depth to soil sodicity constraint maps proved valuable for understanding yield variability, with constraints shallow in the soil profile generally resulting in lower yields, however, this fluctuated by crop type, and seasonal conditions. Future work should create depth-to-constraint maps for several important soil constraints, which may lead to a better understanding of variation in crop yields. An operational framework where farmers are able to add their own soil data to neighbouring and regional soil databases could have considerable benefits for broadacre agricultural industries in Australia.

Calidad del calostro bovino y su relación con la genética, el manejo, la fisiología y su congelación

Objetivo. Los objetivos de este estudio fueron evaluar si la calidad del calostro se modifica por las características genéticas, fisiológicas y de manejo en el período pre-parto, así como evaluar si la calidad y composición del calostro se altera en el proceso de congelación. Material y métodos. En el experimento I, se recogieron muestras de calostro y sangre de 35 vacas (18 Holstein y 17 Jerseys). En el experimento II, se recolectaron seis muestras de calostro de vacas Holstein y se congelaron durante 60 días. Resultados. La concentración media de inmunoglobulina G (IgG) fue de 77.65 mg/ml en Jersey y de 82.77 mg/ml en Holstein. La genética, el orden de parto y la interacción entre estos factores no fueron significativos en la concentración de IgG en el calostro. Además, se observó un efecto genético de la vaca en el peso en la cría al nacer y en los tres días de edad (p&lt;0.0001). Las razas de becerros Holstein (83%) y Jersey (82%) mostraron niveles de proteína sérica total por encima de 5.5 g/dL. Las vacas Holstein alojadas en potreros individuales con suplementos dietéticos, proporcionaron una mejor calidad de calostro (93.57 mg IgG/mL). Con el tiempo, el porcentaje de grasa cambió al congelarse, que se redujo con el tiempo (p&lt;0.05) en el Experimento II. Conclusiones. El manejo previo al parto influye en la calidad del calostro, y la congelación no interfiere en la calidad centesimal e inmunológica del calostro, con excepción de la grasa, que disminuye a lo largo del tiempo.

Temperate grazed grassland carbon balances for two adjacent paddocks determined separately from one eddy covariance system

Use of eddy covariance (EC) as part of net ecosystem carbon balance (NECB) studies of grazed grasslands has the potential to provide valuable insights into the influence of management on soil carbon (C) stocks and opportunities for potential mitigation. However, in rotationally grazed systems where the EC measurements extend across multiple paddocks, often due to necessity, interpretation of results can be complicated by differing paddock-scale management regimes despite being the same land use with a single overarching farm-scale management approach. Here, we calculated separate annual CO2 fluxes and NECBs for two adjacent paddocks under the same general land management using a single EC system for seven years. We were interested in determining whether fluxes and annual NECB of the paddocks were sufficiently similar to allow future side-by-side comparisons of management practices aimed at increasing soil C. We assigned the half-hourly flux measurements to individual paddocks (P31 and P32) using footprint analysis and then gap filled each dataset separately. Additionally, we calculated annual fluxes (and NECBs) for the integrated area of both paddocks (i.e. using all measured flux data; referred to as NewMix). The mean (± 95% confidence interval) NECB for P31 and P32 were 1 ± 76 g C m−2 y−1, and 7 ± 80 g C m−2 y−1, which compared well with the NECB of NewMix (–14 ± 48 g C m−2 y−1). Large between-paddock and inter-annual variability were observed, and several consecutive years of data were required to determine with high certainty that both paddocks were C neutral. Day-to-day management decisions were identified as causing some of the variability. We concluded that the calculation of fluxes and NECB's from two adjacent paddocks using a single EC system was possible, and indeed, likely more insightful and useful than integrating across multiple paddocks. Such an approach can provide opportunities to more accurately quantify management effects, and test mitigation strategies by using treatment and control experiments on adjacent paddocks using a single EC system, although multiple measurement years are likely required. Alternatively, using two EC systems at separate sites, each quantifying both treatment and control fluxes would allow for replication, and thus greater statistical power, which has been a limitation for many EC based NECB studies.

Dried whole cupuassu (Theobroma grandiflorum) nuts as an alternative energy feedstuff for beef cattle grazing tropical pasture

Context Cupuassu is frequently cultivated in Brazil as well as in the warm lowlands of other tropical American countries. Cupuassu nut contains high levels of theobromine and ether extra ct, which could negatively affect the intake and digestibility of nutrients, when included in livestock diets. Aims The present study was undertaken to evaluate how replacing maize with cupuassu nut affects feed intake, efficiency of microbial synthesis and nitrogen (N) balance in Nellore bulls at pasture. Methods Five Nellore bulls with an initial bodyweight of 336.7 ± 12.8 kg (mean ± s.d.) were kept in individual paddocks of Urochloa brizantha cv. Marandu. Concentrate supplements containing equal amounts of N and different concentrations of dried whole cupuassu nut (0%, 25%, 50%, 75% or 100% replacement of maize) were fed to bulls in a 5 × 5 latin square design, with each animal allocated to each diet for a period of 20 days, including a 14-day period of adaptation. Key results Intake of all dietary components and total digestible nutrients, except ether extract, theobromine and neutral detergent fibre corrected for ash and protein, decreased linearly with the addition of cupuassu. Theobromine intake varied from 13.86 (25% cupuassu nut) to 36.67 (100% cupuassu nut) mg/kg bodyweight. The inclusion of cupuassu in the supplement led to a linear decrease in ruminal ammonia-N concentration, N balance, and efficiency of microbial synthesis. Conclusion Replacing maize with dried whole cupuassu nut in concentrate supplements reduces the intake of DM from both supplement and pasture, the efficiency of microbial synthesis, and the N balance in grazing beef cattle. Implications The replacement of maize by dried whole nut of cupuassu in concentrate supplements for grazing cattle is not recommended because it reduces supplement intake and nitrogen retention, and it is likely to decrease liveweight gain.

Homeopathic additives and virginiamycin® in grazing beef cattle

The aim of this study was to evaluate the effects of homeopathic additives and the non-ionophore antibiotic virginiamicin® on intake, digestibility, metabolic characteristics and carcase characteristics in Nellore bulls under supplemented grazing. Twelve uncastrated Nellore bulls were used, with an initial mean weight of 346.04 ± 13.33 kg and initial age of 20.00 ± 2.00 months. The animals were kept in individual paddocks of Urochloa decumbens Stapf. (syn. Brachiaria) and divided into two treatments: Lipomax® - supplement concentrate with homeopathic additives (Convert H®, Sodo 100®, Figotonus®) and a non-ionophore antibiotic (Virginiamycin®); Control - supplement concentrate containing the same protein content, but with no additives. The experiment was carried out in a completely randomised design. Intake, the apparent digestibility of the dietary constituents and the metabolic characteristics of the bulls were not affected by supplementation with additives (P>0.05). Lipomax® improved weight gain in the animals (P 0.05). Supplementation with homeopathic additives and virginiamicina® had a positive effect on performance and on hot and cold carcase weight in grazing Nellore bulls.

Preliminary investigation into the feasibility of combining satellite and GPS data to identify pasture growth and grazing

Regular estimation of pasture availability is a time-consuming on-farm task, but one that is vital for good grazing management. The ability to automate this task is, therefore, highly valuable. Combining satellite sensing of pasture mass with global positioning for herd location provides raw data that can potentially be used to automatically estimate pasture mass, pasture growth and pasture grazing events across a farm. The feasibility of automatically obtaining and processing this information was demonstrated on a Waikato dairy farm from 22 October 2018 to 21 February 2019 (123 days), with 13 global positioning collars recording the location of grazing mobs 16 times per hour on average, in a dairy herd of initially 380 animals. Satellite sensing of pasture cover over the same period was only possible on 16 days during this period, with November being particularly cloudy, resulting in fewer pasture cover estimates. A non-linear regression model was constructed with parameters representing initial pasture cover, average pasture growth rate through time, pasture growth differences between paddocks, pasture disappearance rate relative to the density of cow GPS samples, and an ungrazeable residual. A Bayesian approach was used to infer the model parameters from the satellite-measured pasture cover data. This allowed interpolation of pasture mass through the whole period with an RMSE of 225 kgDM/ha, as well as identifying growth rate differences between paddocks, which may provide a useful basis for improved pasture management. Rough estimates of cow average daily pasture disappearance were also made, which peaked at 20 kgDM/d in November, falling to 5 kgDM/d by February. This pilot study demonstrated the feasibility of combining satellite pasture cover data with herd location data from a small number of GPS collars to infer pasture growth rates in individual paddocks through time.

Elimination behavior and soil mineral nitrogen load in an organic system with lactating sows – comparing pasture-based systems with and without access to poplar (Populus sp.) trees

ABSTRACTInnovative strategies in free-range pig production are needed to improve the environmental performance of the system. Based on previous studies, inclusion of trees was hypothesized to improve the system’s nitrogen efficiency. We investigated sow elimination behavior, feces load, and localization as well as soil mineral nitrogen load in pasture-based individual paddocks with and without access to two rows of poplar (Populus sp.) trees. In contrast to what was expected, sows showed no preference for eliminating in the zone with poplars but clearly avoided defecating near the hut, feed, and water. Soil mineral nitrogen load showed a heterogeneous pattern as also found in previous studies. In comparison to grass, our results indicated that the poplars had an increased winter uptake of nitrate from deeper soil layers.

Inclusion of copaiba oil (Copaifera sp.) as additive in supplements for cattle on pasture

SUMMARY This study analyzed the effect of including copaiba oil as an additive for cattle supplemented on pasture, during the dry season. Four crossbred steers, castrated, with 245 ± 25 kg, aged about 18 months, fitted with permanent rumen cannula; were randomly assigned to a 4×4 Latin square. All animals were housed in individual paddocks (0.3 ha), uniformly covered with Brachiaria brizantha cv Marandu, with through and drinking fountain; and were given a concentrate at 500g/100 kg BW containing 380 g/kg crude protein (%DM). The copaiba oil was added to the supplement as a spray, in the proportions of 0, 0.5; 1.0 and 1.5 g/kg DM intake. Spraying supplementation was performed daily at the time of supply of the supplement. Data of intake and digestibility of nutrients, ruminal pH; ruminal ammonia nitrogen, and microbial protein synthesis were tested by analysis of variance and polynomial regression, adopting a significance level of 5%. The inclusion of copaiba oil quadratically affected total dry matter intake (P=0.030) and CP digestibility (P=0.043), without altering ruminal metabolism (P&gt;0.05) and microbial protein synthesis (P&gt;0.05) of the animals kept on pasture.

Regular estimates of herbage mass can improve profitability of pasture-based dairy systems

Paddock selection is an important component of grazing management and is based on either an estimate of herbage mass, or the interval since last grazing for each paddock. Obtaining estimates of herbage mass to guide grazing management can be a time consuming task. A value proposition could therefore assist farmers in deciding whether to invest resources in obtaining such information. A farm-scale simulation exercise was designed to estimate the effect of three levels of knowledge of individual paddock herbage mass on profitability of two typical pasture-based dairy systems in New Zealand; a medium input system stocked at 3.2 Friesian-Jersey cross bred cows/ha with ~15% imported feed, and a high input system stocked at 4.5 Friesian cows/ha with ~40% imported feed. The three levels of knowledge were: (1) ‘perfect knowledge’, where herbage mass per paddock is known with perfect accuracy, (2) ‘imperfect knowledge’, where herbage mass per paddock is estimated with an average error of 15%, (3) ‘low knowledge’, where herbage mass is not known, and paddocks are selected based on longest time since last grazing. In both systems, grazing management based on imperfect knowledge increased farm operating profit by ~NZ$385/ha at a milk price of NZ$6.33/kg milksolids (fat + protein) compared with low knowledge. Perfect knowledge added a further NZ$155/ha to profit. The main driver of these results is the level of accuracy in daily feed allocation, which increases with improved knowledge of herbage availability. This allows feed supply and demand to be better matched, resulting in less incidence of under- and over-feeding, higher milk production, and more optimal post-grazing residual herbage mass to maximise herbage regrowth.

Soil cadmium and New Zealand dairy farms: Impact of whole-farm contaminant variability on environmental management

Two long-term dairy farms with different phosphorus (P) fertiliser application history in the North and South Island of New Zealand were studied to understand factors influencing the spatial distribution of soil cadmium (Cd). Intensive soil sampling within each farm showed that soil Cd concentrations (0–150 mm depth) were much greater and more variable in the Waikato (North Island) farm (mean: 1.04 mg kg−1, range: 0.48–1.64 mg kg−1) than the Canterbury (South Island) farm (mean: 0.34 mg kg−1, range: 0.15–0.64 mg kg−1). A significant (P < 0.001) relationship between total soil Cd and total P indicated the overriding influence of P fertiliser application history on soil Cd accumulation. However, within land management units (LMUs) of common P fertiliser history, soil type had a significant (P < 0.001) influence on soil Cd concentration. Slope class had no influence (P = 0.491) on soil Cd concentration within the range of 0−15°. There was no clear, consistent relationship between soil Cd and land-based effluent disposal on either farm. Given the large spatial variability in soil Cd concentration that was evident within the two farms of this study, it is recommended that sampling strategies used for the assessment of soil Cd (e.g. under environmental regulation/management frameworks) need to account for variation in land use, P fertilisation history, and soil type. Sampling individual paddocks based on predominant soil type will also allow areas to be identified where there is heightened risk of plant Cd accumulation.