Paddock Grazing Research Articles

Climate Effects on Tallgrass Prairie Responses to Continuous and Rotational Grazing

Cattle grazing is an important economic activity in the tallgrass prairie systems in the Great Plains of the United States. Tallgrass prairie may respond differently to grazing management (e.g., high and low grazing intensity) under variable climate conditions. This study investigated the responses of two replicated (rep a and rep b) tallgrass prairie systems to continuous (C) and rotational (R) grazing under different climate conditions over a decade (2008–2017). The enhanced vegetation index (EVI) and gross primary productivity (GPP) were compared between grazing systems (C vs. R), while EVI was compared among paddocks under rotational grazing to show the impacts of time since grazing. The average EVI in rep a was usually higher than that in rep b which could be explained by different land characteristics (e.g., soil types) associated with different landscape positions. Similar to EVI, GPP was usually higher in rep a than rep b. The average growing season EVI and GPP were higher in rotational grazing than continuous grazing in rep b but not in rep a. The average EVI of paddocks in rotational grazing systems only converged in the growing season-long drought year (2011). In other years, EVI values varied from year to year and no paddock consistently outperformed others. The variations in EVI among rotational grazing paddocks in both reps were relatively small, indicating that rotational grazing generated an even grazing pressure on vegetation at annual scale. Overall, climate and inherent pasture conditions were the major drivers of plant productivity. However, the stocking rate in continuous grazing systems were reduced over years because of deteriorating pasture conditions. Thus, the results indirectly indicate that rotational grazing improved grassland productivity and had higher stocking capacity than continuous grazing systems under variable climate conditions. Adaptive grazing management (adjustment in stocking rates and season of use to adapt to changing climatic conditions) instead of a fixed management system might be better for farmers to cooperate with changing climatic conditions.

Response of Soil Chemical Properties to Irrigation with Winery Wastewater on a Well-drained Sandy Soil

Most wineries in South Africa dispose of their wastewater through land application. This is carried out by irrigating small areas of cultivated pasture with the wastewater or ponding, with the former being the more general practice. Land application of winery wastewater results in the accumulation of potassium (K+) and sodium (Na+) in the soil and leaching of calcium (Ca2+) and magnesium (Mg2+).This could lead to long term instability of soil structure. The objective of this study was to investigate the effect of irrigation with winery wastewater on chemical soil properties and potential environmental impacts. Therefore, an existing grazing paddock at a winery near Rawsonville was selected where wastewater had been applied for many years. Due to the high volumes of wastewater irrigation plus rainfall, the inevitable over-irrigation leached large amounts of cations, particular K+ and Na+, beyond 90 cm soil depth at the selected study site. These leached elements are likely to end up in natural water resources in the long run. Irrigation with winery wastewater did not have a pronounced effect on soil pH(KCl). This was probably due to the decomposition of organic matter, and the fact that the applied salts were leached beyond 90 cm depth. The study confirmed that disposal of winery wastewater through land application can only be recommended where wastewater application will not exceed the water requirement of the crop as well as the water holding capacity of the soil which is being irrigated.

Soil physical and chemical properties in response to long-term cattle grazing on sloped rough fescue grassland in the foothills of the Rocky Mountains, Alberta

Soil physical and chemical properties are critical indicators for soil health assessment. It is important to understand how these qualities respond to different grazing intensities at different landscape slope positions. This study evaluated how soil physical and chemical properties respond to cattle grazing intensity and slope position on a rough fescue grassland. Cattle have been grazing at four stocking rates, 0, 1.2, 2.4 and 4.8 animal-unit-months (AUM) ha−1 since 1949 to simulate Control (CK), Light (L), Heavy (H), and Very Heavy (VH) grazing intensities. Surface soil penetration resistance was measured using a portable penetrometer and soil samples were taken from the top and bottom slope positions for each grazing paddock (but only from the top position for CK) in September 2016. Soil texture, aggregate stability, pH, available phosphorus (AP), water-soluble ions concentration and soil cation exchange capacity (CEC) were determined. Bulk density, porosity and hydraulic properties were measured using a HYPROP system. The S-index, the slope at the inflection point on the soil moisture retention curve, was calculated. Soil clay and silt contents were lower in VH than L treatments; total porosity, air capacity, and saturated water content followed the same pattern. However, the opposite was true for sand content, penetration resistance, and bulk density, with differences between the two grazing treatments greater at the top than the bottom slope position. Grazing changed the shape of soil moisture retention curve in both slope positions with the curve steeper in L than H and VH treatments. The S-index and saturated hydraulic conductivity were reduced by grazing but their responses to slope position and its interaction with grazing intensity were not significant. Soil pH, AP, and water-soluble Na+, K+, Mg2+, Ca2+ and SO42− concentration increased with the animal stocking rate while Cl− and CEC were not affected. Similarly, greater increases in soil pH with increased animal stocking rates were observed in the top than bottom position, while AP, Na+, K+, and SO42− increased with animal stocking rate only in the bottom position. Our results indicate that soil physical properties may be more sensitive to grazing at the top than bottom of a slope. Thus, slope should be considered when developing rangeland soil health assessment indices and grazing management strategies.

CAUSES OF FARMERS-PASTORALISTS’ CONFLICT AND MITIGATION: A PANACEA FOR SUSTAINABLE NATURAL RESOURCE MANAGEMENT IN WESTERN ZONE OF BAUCHI STATE, NIGERIA

This study assessed the causes of farmers-pastoralists’ conflict and mitigation: A panacea for sustainable natural resource management in western zone of Bauchi State, Nigeria. Data were collected using questionnaire using descriptive statistics as analytical tool. Purposive simple random sampling technique was used to select 75 arable farmers and 75 pastoralists. Purposive sampling was employed to be enabling the researcher to capture pastoralist who were sparsely distributed. The result shows that most (73.91%) of the respondents perceived that conflicts do occur in the study area. The result also reveals that 59.40% of the respondents agreed that conflict frequently occurred only during rainy season. The results further reveals that, the major causes of conflicts include lack of defined cattle route (54.05%), poor government attitude toward agricultural development (52.03%) and inadequate grazing reserves (51.35%) among others. Also, 22.30% and 20.95% of the respondents reported that, pastoralist-fisher folks and farmer-hunter conflicts also occurred, respectively, in the study area. The result further reveals that major losses incurred due to conflicts include destruction of crops (92.46%), body injury (89.59%), loss of Livestock (57.32%), destruction of houses (52.44%) among others. Seventy five percent of the respondents perceived that youth were the major victims of conflict in the study area. The major constraints to conflict prevention and management include inadequate social infrastructures (91.21%), poverty (86.49%) and failure of government to implement agricultural policies (84.49%) among others. The study recommend that provision of adequate infrastructures (e.g., dams, grazing reserves, etc.) and sensitizing pastoralists to establish private grazing paddocks and boreholes will stem down the occurrence of conflict and subsequently enhance sustainable livestock production in the study area.

Positive effects of goat pasturing on the threatened spring geophyte Gagea bohemica in formerly abandoned dry grasslands

Goat pasturing is often recommended for managing shrub-encroached dry grasslands, but entails higher grazing pressure. However, there have been few studies about the effects of goats on assumedly grazing sensitive geophytes. Therefore, in conservation practice, low-intensity migratory herding is still preferred in dry grasslands inhabited by threatened geophytes, even when shrub encroachment is already advanced.We compared the effects of restorative goat paddock grazing and low-intensity migratory sheep herding on the performance of Gagea bohemica (Liliaceae) a threatened spring geophyte. For this purpose, we recorded G. bohemica cover as well as numbers of flowering and non-flowering individuals on a total of 24 permanent plots in 2013, 2014 and 2016 in three study areas in Central Germany. In 2014, all flowering plants were monitored weekly for mature seeds. In addition, we sampled litter layer cover as a proxy for grazing intensity to analyse the effects of this habitat feature on the abundance of G. bohemica.Overall, G. bohemica cover and individual numbers were higher in paddocks than in migratory herding sites. The best performance was recorded in plots with low litter layer cover. Only 5.9% of the observed individuals flowered and only 0.3% produced visible seed sets in 2014.In abandoned dry grasslands, G. bohemica benefits from a relatively high grazing pressure, resulting in a lower litter cover and subsequently higher light availability at ground level. Due to its low seed set and ability to reproduce vegetatively by subterranean bulbils, ground disturbance by livestock trampling may also constitute an important factor supporting short-distance dispersal of G. bohemica. Goat grazing is a successful tool to restore shrub-encroached dry grasslands with existing remnant populations of spring geophytes. We recommend paddock grazing by goats with a high grazing pressure starting in April after above-ground parts of G. bohemica have already withered.

Phosphorus Characterisation of Sludge and Crust Produced by Stabilisation Ponds in a Dairy Manure Management System

In dairy farming, recirculation and continuous use of nutrients are necessary for sustainable nutrient management in both the short- and long-term. When managed effectively, nutrient recycling can improve soil fertility. On the other hand, if applied nutrients are in excess of the soil’s nutrient holding capacity, nutrients can enter surface and ground water bodies resulting in eutrophication. Phosphorus (P) characterisation in manure, pond sludge and crust, in terms of plant availability, is the first step to sustainably manage nutrients within dairy farms. In this study, pond sludge and crust were characterised for P using a sequential fractionation method. Pond sludge and crust contained significant amounts of labile P. Water extractable P (H2O-P) in primary anaerobic pond and secondary facultative pond sludges was found to be about 8 to 13 times higher than the amount found in the surface soil (0–10 cm) of a grazing paddock. Similarly, sodium bicarbonate extractable P (NaHCO3-P) in the two types of sludges was found to be about 6 times higher than in the soil. The relatively higher labile P (H2O-P and NaHCO3-P) in sludge compared to soil indicates that the sludge can be utilised as a P fertilizer on grazing pasture. In contrast, lower H2O-P compared to that of raw manure indicates that the use of sludge and crust instead of raw manure can reduce the possibility of P loss by surface runoff and leaching. Hence, it is preferable to use pond sludge and crust as fertiliser instead of raw manure.

Rodent occupancy in grassland paddocks subjected to different grazing intensities in South Brazil

Livestock is promoting the global collapse of mammal populations. The discovery of the best management practices that reconcile conservation with production is urgently needed. We evaluated the effect of cattle grazing on the occupation of three rodent species (Akodon azarae, Oligoryzomys flavescens and Oxymycterus nasutus). We collected habitat covariates and sampled rodents, using live traps and tracking tunnels, in 20 paddocks subjected to different grazing pressures, from two research stations, across four seasons. We applied single-season occupancy modeling to determine whether rodent detection and occupation varied as a function of the covariates describing sampling occasions and grazing intensity. We ran sensitivity analyses to evaluate the effect of the differential sampling effort we applied across research stations. All species had higher detection probabilities during the winter. O. nasutus showed a higher detection probability under tall vegetation. A. azarae reached a higher occupation probability in ungrazed areas, although it also had a low probability of occupation in highly grazed paddocks. O. flavescens occupation seemed constant across the grazing gradient. O. nasutus reached a higher occupation probability in ungrazed areas. Decreasing stocking rates and maintaining ungrazed areas might compose the best management practices for small mammal conservation in the grasslands of Southern Brazil.

Implementation of CTR Dairy Model Using the Visual Basic for Application Language of Microsoft Excel

The goal of the article is to implement the CTR Dairy model using the Visual Basic for Application (VBA) language of Microsoft Excel. CTR Dairy is a dynamic simulation model for grazing lactating dairy cows that predicts milk production and profit over feeding based on ruminal digestion and absorption of nutrients under discontinuous feeding schedules. The CTR Dairy model was originally developed as a research tool using a proprietary computer simulation software called SMART that required the SMART client to run the program. As SMART software is now discontinued, and its client is no longer available, rewriting the model in the VBA language using Microsoft Excel for inputs and outputs makes the program available to a broad range of users including dairy farmers, extension advisors, dairy nutrition consultants and researchers. Dairy farmers can use the new version of the CTR Dairy program to manipulate the herbage allowance and the access time to the grazing paddock, as well as the timing of supplemental feeding, to improve the utilization of the pasture and to increase the production of the milk.

Case Study: Documenting grass growth and productivity in a grass-based organic dairy in Oregon

Managing pastures on grazing dairies is a continuous challenge because pasture quality, quantity, and growth rate are changing daily. The objectives of this study were to document weekly pasture growth, forage quality, and performance to understand how to use this information to make management decisions on US dairies. One organic grazing dairy was studied for 3 consecutive years. Pastures were measured and mapped, and total standing DM was estimated weekly in all 22 pastures using a calibrated rising plate meter. Weekly grazing wedges were developed and were used to make grazing decisions that week. Paddocks grazed and residual pasture covers were recorded daily. Paddock grazing and residual heights were also included in the electronic recordkeeping. Dry matter yields ranged from 11,277 to 22,346 kg/ha per year and averaged 15,887 ± 1,919, 17,848 ± 1,966 and 17,956 ± 2,014 for each consecutive year. Daily growth rates ranged from 18 to 100 kg/ha per day throughout the season and averaged as high as 56 ± 20.3 kg/ha per day in yr 3. Pasture quality and productivity in Oregon is comparable to some of the most productive dairy pasture systems reported from around the world.

Applicability of Eddy Covariance to Estimate Methane Emissions from Grazing Cattle.

Grazing systems represent a significant source of enteric methane (CH), but available techniques for quantifying herd scale emissions are limited. This study explores the capability of an eddy covariance (EC) measurement system for long-term monitoring of CH emissions from grazing cattle. Measurements were made in two pasture settings: in the center of a large grazing paddock, and near a watering point where animals congregated during the day. Cattle positions were monitored through time-lapse images, and this information was used with a Lagrangian stochastic dispersion model to interpret EC fluxes and derive per-animal CH emission rates. Initial grazing paddock measurements were challenged by the rapid movement of cattle across the measurement footprint, but a feed supplement placed upwind of the measurements helped retain animals within the footprint, allowing emission estimates for 20% of the recorded daytime fluxes. At the water point, >50% of the flux measurement periods included cattle emissions. Overall, cattle emissions for the paddock site were higher (253 g CH m adult equivalent [AE] d, SD = 75) and more variable than emissions at the water point (158 g CH AE d, SD = 34). Combining results from both sites gave a CH production of 0.43 g kg body weight, which is in range of other reported emissions from grazing animals. With an understanding of animal behavior to allow the most effective use of tower placement, the combination of an EC measurement platform and a Lagrangian stochastic model could have practical applications for long-term monitoring of fluxes in grazing environments.

Sward height management, desiccation time of Urochloa ruziziensis and nitrogen fertilization of soybean under crop-livestock system

The integration of soybean crop with pastures is an important strategy to diversify the grain production systems in Brazil. The objective of this research was to evaluate the effect of grazing intensities in Urochloa ruziziensis, desiccation time of the pasture in relation to soybean sowing and crop fertilization with mineral nitrogen on the growth and yield of soybean, cultivar NK 7059 RR. Three grazing intensities of U. ruziziensis (15, 35 and 50 cm of plant height), were grazed continuously for six months, plus a no grazing paddock, making four experiments, were evaluated. In each experiment a randomized complete block design with three replications in a split plot design was used. In the plots were allocated four desiccation time of the pasture (35, 28, 20 and 8 days before soybean sowing) and in the subplots, nitrogen fertilization in soybean (without N or with 30 kg N ha-1 at sowing). Initially, analysis of each experiment was performed and subsequently a joint analysis was performed. The grazing intensities did not significantly affect the soybean growth and the yield. The increased interval between pasture desiccation and soybean seeding and the nitrogen fertilization on crop promoted increments in the growth and N accumulation by soybean in early development cycle. On the other hand, in the reproductive phase, these differences were negligible and did not affected the yield.

Effect of probiotic Bacillus amyloliquefaciens strain H57 on productivity and the incidence of diarrhoea in dairy calves

A spore-forming probiotic, Bacillus amyloliquefaciens strain H57 (H57), was administered to dairy calves in starter pellets to determine effects on liveweight gain, feed conversion efficiency and animal health under summer feeding conditions, without antibiotics. Twenty-four male and female calves were allocated into two groups and from 4 weeks of age individually offered 6 L/day of whole milk and ad libitum starter pellets impregnated with H57 (3.16 × 108 cfu per kg DM) or without (Control) until 12 weeks of age. The calves were housed in a non-air-conditioned animal house, with deep-straw bedding over concrete, under typically challenging subtropical summer conditions. After 12 weeks the calves were released into a grazing paddock as one group and were supplemented ad libitum with control pellets and hay, until 19 weeks of age. From Weeks 4 to 12, liveweight and feed intakes were measured weekly and health status was monitored daily. Rumen fluid and blood were collected at Weeks 4 and 12, and to test for persistence after cessation of feeding H57, each were measured again at Week 19. From Weeks 4 to 12, the H57 calves grew faster (767 vs 551 g/day, P = 0.01), tended to consume more pellets (1013 vs 740 g DM/day, P = 0.07) and were 19% more feed conversion efficiency (2.43 vs 2.90 kg milk + starter DM/kg weight gain, P = 0.01) compared with the Control calves. The mean duration of each diarrhoea event was 2 days less for the H57 calves than the Control (P = 0.01). The H57 calves weaned 9 days earlier (P = 0.02) and were heavier at Week 19 (155 vs 139 kg, P = 0.03) than the Control calves. The only effect of H57 on rumen volatile fatty acid concentrations was an elevation in valerate at Week 12 (4.10 vs 2.47 mmol/L, P = 0.03). Plasma β-hydroxy butyrate was also elevated in the H57 calves at Week 19 (0.24 vs 0.20 mmol/L), indicating the potential of H57 to improve rumen development. H57 can be used to improve the nutritional performance and reduce the risk of diarrhoea in dairy calves as they transition from milk to dry feed.

Invasive spread dynamics of Anthriscus caucalis at an ecosystem scale: propagule pressure, grazing disturbance and plant community susceptibility in canyon grasslands

Several factors may influence invasive spread dynamics once a species becomes naturalized. Propagule pressure generated from established populations is likely mediated by local scale factors such as plant community characteristics and disturbance regimes as well as ecosystem scale factors such as landscape features that shape dispersal patterns and propagule availability. Using a multi-scale observational approach, we explore how propagule pressure generated from naturalized populations of Anthriscus caucalis (M.-Bier) influences invasive spread dynamics in the Snake River canyon grassland ecosystem of the Intermountain Pacific Northwest, USA. In this study, we utilize demographic insights into A. caucalis naturalization across plant communities and a companion ecosystem scale distribution survey to elucidate invasive spread dynamics using spatially-explicit SDMs. We modeled A. caucalis occurrence as a function of plant community type, grazing disturbance, and propagule pressure generated from high-shrub communities. A. caucalis was almost uniformly present in low- and high-shrub (>90 %) communities. Within bunchgrass communities, A. caucalis occurrence was significantly lower within grazed paddocks (3 %) compared to ungrazed paddocks (52 %). The probability of A. caucalis occurrence in bunchgrass communities within ungrazed paddocks also increased at a faster rate as the relative area of high-shrub communities increased. These results suggest propagule pressure generated from high-shrub communities strongly influence invasive spread into bunchgrass communities. Our results also suggest that livestock disturbance slows invasive spread by decreasing propagule supply from high-shrub communities. Plant community composition also contributed to A. caucalis occurrence patterns within bunchgrass communities. A. caucalis occurrence declined as native bunchgrass cover increased, whereas occurrence increased with increasing cover of exotic annual species. As native bunchgrass cover declined, A. caucalis occurrence increased in locations with greater relative area of high-shrub communities. These results suggest that undisturbed bunchgrass communities are resistant to A. caucalis invasion regardless of propagule supply. In disturbed bunchgrass communities dominated by exotic annuals, A. caucalis invasion levels were positively associated with increased propagule pressure generated from high-shrub communities. In conclusion, the coupling of comparative demographic observations with spatially-explicit SDMs yielded significant insights into invasive spread dynamics. This approach should be applicable for elucidating invasive spread dynamics of other invading plant species and ecosystems.

Nitrogen balance in Holstein steers grazing winter oats: effect of nitrogen fertilisation

The present study evaluated the effect of nitrogen (N) fertilisation of winter oats on whole-animal N balance (N intake, N excretion in urine and faeces, N retention), partition of urinary N (purine-N derivatives and urea-N) and average daily gain (ADG) in grazing steers. The experimental area was divided in two plots (10 steers/plot), and samples were obtained in two periods (one plot/period).The experimental area was divided in two plots, and each plot in 10 strips. Twenty Holstein steers (161.3 ± 7 kg of initial bodyweight) grazed, for 51 days, individual strips of fertilised (100 kg N/ha; N100) and non-fertilised (N0) winter oats during daylight (10 h/day). The daily individual grazing paddock was adjusted to offer 6 kg DM of green leaf·100 kg/BW.day. Chemical composition of the herbage and N diurnal variation were estimated by collecting three samples per paddock at 0830 hours, 1330 hours and 1830 hours, twice on each sampling period. Forage intake and in vivo digestibility were estimated by the n-alkane technique. Individual N intake was estimated using n-alkane data, the ingestive behaviour data and the diurnal variation of the chemical composition of the forage. N fertilisation increased N content [P < 0.01; N0 = 11.4% crude protein (CP) vs N100 = 13.9% CP] and decreased the water-soluble carbohydrate content (P < 0.01; N0 = 21.1% vs N100 = 16.8%) in the forage, but did not modify herbage mass or the DM content. Dry matter intake (4.72 kg DM/day), water intake (7.57 L/day) and DM digestibility (67%) were not affected by N fertilisation. However, N intake and N digestibility were higher in N100 than in N0 (20 vs 7 g N/day). Although treatments had similar faecal N excretions (average 45.4 g N/day), there was a trend to increase urinary N excretion with N intake (P = 0.08; N100 = 53.3 vs N0 = 47.5 g N/day), a trend to increase N-allantoin excretion (P = 0.11; N100 = 3.18 vs N0 = 2.91 g/day) and an increase in urea-N excretion (P < 0.01; N100 = 30.7 vs N0 = 23.8 g/day). Increasing N intake led to greater N retention (P < 0.02; N100 = 37.9 vs N0 = 20.9 g N/day) and ADG (P < 0.03; N100 = 860 vs N0 = 698 g/day). These results suggest that fertilising winter oats with 100 kg N/ha improves N retention and ADG in young steers under grazing conditions.

Comparison of Beef Cattle Grazing Management Practices and their Effects on Runoff Water Quality in Louisiana

Management-intensive grazing (MIG) allows better use of grazed forage crops with short-duration grazing in small paddocks and with this study; the water quality was compared for two grazing management methods. Year-round grazing with MIG and continuous stocking (CS) were compared. Four 0.81-ha plots for two replications of the grazing systems were established. Twenty 0.04 ha (0.1 ac) paddocks, established with power fencing, allowed daily cattle rotation in MIG system. Continuous grazing and MIG used the same stocking rate on each experimental plot (0.81 ha). Each year, two crossbredbeef (Bos taurus) heifers (390 kg ± 12 kg; 12-14 mo at start) were maintained on each plot year-around for 3 yr, with additional yearling heifers added to maintain similarforage availability between stocking methods. Common bermudagrass (Cynodon dactylon [L] Pers.) was grazed in summer and annual ryegrass (Lolium multiflorum Lam.) was over-seeded into the sod during October for winter and spring grazing. Forage mass was determined monthly and available forage dry matter (DM) was maintained at approximately 1120 kg DM ha-1 Runoff water samples were collected during 42 rainfall events from May 2001 through March 2004. No significant treatment differences (P > 0.10) were found in most of the water quality parameters. Runoff as a percentage of the 3-yr average annual rainfall of 1869 mm was 34% for MIG and 42% CS. The average flow-weightedconcentrations of soluble reactive phosphorus (SRP) varied from 5.08 mg P L–1 (ppm) to 8.22 mg P L–1 (ppm) while the NH+4–N ranged from 1.07 mg N L–1 (ppm) in year one to 10.11 mg N L–1 (ppm) for the second year (P < 0.05) for year effect. Total annual average forage production was greater (P < 0.05) in the MIG compared to CS with19,796 kg ha-1 for MIG vs. 16,964 kg ha-1 for CS. Beef production also increased with the MIG system with an annual total beef gain from MIG at 422 kg ha-1 y-1 vs. CS at 330 kg ha-1 yr-1.

Anthelmintic resistance in gastrointestinal nematodes in goats and evaluation of FAMACHA diagnostic marker in Uganda

Gastrointestinal nematodes (GIN) are a challenge to goat production globally causing reduced growth, morbidity and mortality. We report here results of the first nation-wide anthelmintic resistance (AR) study and validation of assessment of clinical anaemia with FAMACHA eye scores in goats in Uganda. From August to December 2012 the efficacy of albendazole (7.5mg/kg), levamisole (10.5mg/kg) and ivermectin (0.3mg/kg) against strongyle nematodes was tested on 33 goat farms in Soroti, Gulu, Mpigi, Mbarara and Ssembabule districts of Uganda. Altogether 497 goats were subjected to a total of 45 different faecal egg count reduction tests (FECRT), each involving 5–20 goats. On one farm all substances were tested. Faecal and blood samples were collected and FAMACHA eye scores evaluated on the day of treatment and 15 days later. A questionnaire survey was conducted on frequency, type and dose of anthelmintics used, farm size and grazing management system. Examination of infective third stage larvae (L3) from pooled faecal cultures demonstrated Haemonchus to be the predominant genus (>75%). Resistance to at least one anthelmintic group was detected on 61% of the 33 farms and in 49% of the 45 test groups. Prevalence of resistance to ivermectin, levamisole and albendazole was respectively 58%, 52% and 38%. Correlation between pre-treatment packed cell volume determinations and FAMACHA scores (r498=−0.89) was significant. Paddock grazing system (Odds ratio 4.9, 95% CI 1.4–17.3) and large farm size of >40 goats (odds ratio 4.4, 95% CI 1.2–16.1) were significant predictors of AR. In all districts, resistance to all three anthelmintics was higher on large-scale goat farms practising mostly paddock grazing. Interestingly, resistance to albendazole, the most commonly used anthelmintic in Uganda, was lower than that to ivermectin and levamisole. We recommend adaptation of FAMACHA to goats to help restrict anthelmintic treatment to heavily infected individuals. This will limit selection pressure and hence delay development of anthelmintic resistance.

A comparison of stocking methods for beef production in northern Australia: pasture and soil surface condition responses

Historical stocking methods of continuous, season-long grazing of pastures with little account of growing conditions have caused some degradation within grazed landscapes in northern Australia. Alternative stocking methods have been implemented to address this degradation and raise the productivity and profitability of the principal livestock, cattle. Because information comparing stocking methods is limited, an evaluation was undertaken to quantify the effects of stocking methods on pastures, soils and grazing capacity. The approach was to monitor existing stocking methods on nine commercial beef properties in north and south Queensland. Environments included native and exotic pastures and eucalypt (lighter soil) and brigalow (heavier soil) land types. Breeding and growing cattle were grazed under each method. The owners/managers, formally trained in pasture and grazing management, made all management decisions affecting the study sites. Three stocking methods were compared: continuous (with rest), extensive rotation and intensive rotation (commonly referred to as ‘cell grazing’). There were two or three stocking methods examined on each property: in total 21 methods (seven continuous, six extensive rotations and eight intensive rotations) were monitored over 74 paddocks, between 2006 and 2009. Pasture and soil surface measurements were made in the autumns of 2006, 2007 and 2009, while the paddock grazing was analysed from property records for the period from 2006 to 2009. The first 2 years had drought conditions (rainfall average 3.4 decile) but were followed by 2 years of above-average rainfall. There were no consistent differences between stocking methods across all sites over the 4 years for herbage mass, plant species composition, total and litter cover, or landscape function analysis (LFA) indices. There were large responses to rainfall in the last 2 years with mean herbage mass in the autumn increasing from 1970 kg DM ha–1 in 2006–07 to 3830 kg DM ha–1 in 2009. Over the same period, ground and litter cover and LFA indices increased. Across all sites and 4 years, mean grazing capacity was similar for the three stocking methods. There were, however, significant differences in grazing capacity between stocking methods at four sites but these differences were not consistent between stocking methods or sites. Both the continuous and intensive rotation methods supported the highest average annual grazing capacity at different sites. The results suggest that cattle producers can obtain similar ecological responses and carry similar numbers of livestock under any of the three stocking methods.

Opportunities to improve grazing management

Abstract Improved efficiency in growing and converting pasture into product is required to maintain New Zealand's competitive advantage in dairying. This study focused on two areas of grazing management, the first an assessment of the indicators leaf stage, pre-grazing yield and grazing residual. In summary, 49% of measured paddocks were grazed too soon based on leaf stage, 62% were grazed outside the recommended pre-grazing yield, and 48% of measured paddocks were not grazed to a desirable height. The second part of the study provided an insight into farmer decision making at an operational level of grazing management with three key components identified. These were: 1) The recruitment of paddocks into a grazing plan; 2) The shuffling of the paddock grazing sequence within the grazing plan; and 3) The management of individual grazing events before, during and after the event. An improved understanding by rural professionals of grazing management decision making would result in extension strategies which generate increased farmer engagement, adoption of grazing management technologies and improved onfarm productivity. Keywords: dairy, grazing management

Circannual body reserve dynamics and metabolic profile changes in Romane ewes grazing on rangelands

Throughout an entire year, 41 Romane ewes reared in an extensive rangeland were used to investigate temporal changes in body reserves (BRs) and profiles of related metabolites and metabolic hormones. Ewes were allocated to homogeneous groups according to BW and BCS and were distributed by parity (primiparous [PRIM], n = 21; multiparous [MULT], n = 20) and litter size (LSi; lambing singletons [SING], n = 21 or TWINS, n = 20). The feeding system was based on rotational grazing of rangeland paddocks and progressive supplementation with hay, silage, and barley at late pregnancy during the winter. Individual BW, BCS, plasma NEFA, β-hydroxybutyrate (β-OHB), glucose, insulin, leptin, and triiodothyronine (T3) were monitored at −56, −12, 8, 49, 76, 107, 156, 195, 216, 246, and 301 d relative to lambing. The BR mobilization was observed from late pregnancy to the end of suckling and varied as a function of the ewe energy balance but also because of transitions from fertilized to native rangeland paddocks and by supplementation. Contrarily, BR accretion occurred from weaning, during the dry-off, and until the start of the next pregnancy. Lipolysis was well reflected by NEFA, β-OHB, and T3 kinetics. Mean BW (but not mean BCS) was affected by parity (MULT > PRIM), whereas both BW and BCS were influenced by LSi (SING > TWINS) but only for MULT. The most drastic BW loss was observed during the mid-suckling period (49 d in milk [DIM]) in all ewes. The lack of effects of LSi in PRIM but not in MULT was also evident in the majority of blood plasma kinetics, which were affected (P < 0.0001) by physiological stage in all ewes. A tendency to ketosis (β-OHB) was found in ewes nursing TWINS around lambing, irrespective of parity. Glucose concentrations were greater during suckling and dry-off, and a peak (0.96 ± 0.05 g/L) was attained at 156 DIM in MULT nursing TWINS. The highest plasma leptin concentration was observed during the start and the middle of the next pregnancy in MULT (107–216 DIM; 9.6 ± 0.44 ng/mL). In all ewes the physiological stage affected T3, which was affected by LSi just in MULT (from late pregnancy, MULT by SING > MULT by TWINS; 99.91 vs 85.52 ng/dL) and during suckling (111.7 ± 4.18 ng/dL). Lamb BW was affected at birth and weaning by parity (MULT > PRIM) and LSi (SING > TWINS). Overall, temporal changes in BR were directly affected by the transition of physiological states and feeding levels, whereas individual responses were predetermined by parity. In MULT, the reactivity and magnitude of response was influenced by LSi. The whole set of parameters allowed us to detect sensitive and critical periods throughout the entire annual cycle. We thus identified opportunities for improved nutritional management, for example, during physiological states usually underestimated such as early and mid-pregnancy. This work indicates the applicability of long-term studies about BR dynamics in ruminants as a potential component contributing to farm economic resilience.

Faecal near-infrared reflectance spectroscopy (NIRS) compared with other techniques for estimating the in vivo digestibility and dry matter intake of lactating grazing dairy cows

The objective of this study was to validate near-infrared reflectance spectroscopy (NIRS) applied to faeces (FNIRS) for estimating the grass in vivo organic matter digestibility (G-OMD) and the grass dry matter intake (G-DMI, kg/d) of concentrate-supplemented grazing dairy cows. The G-OMD estimates from one FNIRS model were compared with two estimates using faecal nitrogen indicator (FNI) methods. Similarly, two FNIRS models were compared with the ratio technique (RT) and with three animal performance methods (APM) for estimating G-DMI. The results were analysed at cow and herd level in two grazed paddocks (P1 and P2) in a rotational grazing scheme.For both G-OMD and G-DMI, the FNIRS estimations were correlated (P<0.05) with other predictive methods (r=0.61 for G-OMD and r=0.63–0.88 for G-DMI). Depending on the estimation method, the G-OMD varied from 0.689 (FNIRS) to 0.773 (FNI). The FNI estimates were generally higher and were similar to the G-OMD estimates obtained from NIRS analyses of grass sampled in the field. The FNIRS and FNI estimates were biased at cow and paddock level by 0.01–0.1 digestibility units (P<0.001).Depending on the estimation method, the G-DMI estimates varied from 11.9 to 16.4kg/d. FNIRS and APM produced similar estimates of G-DMI at both cow and herd level. The RT estimates of G-DMI were 3kg/d higher than the FNIRS and APM estimates (P<0.05). The G-DMI estimated by RT methods was particularly high for P2, with a mean value of 18.5kg/d, which seemed too high in terms of the maximum intake capacity of supplemented grazing dairy cows.For both G-OMD and G-DMI and for all the estimation methods, inter-cow and intra-paddock variations, expressed through the coefficient of variation (SD/mean), ranged from 0.05 to 0.40. As the accuracy of the FNIRS models, expressed through the standard error of cross validation (SECV), was lower than these inter-animal and intra-paddock variations, we suggest that FNIRS could be used to record, quickly and easily, the evolution of grass digestibility and the intake of grazing dairy cows. These estimates could be implemented through decision-support systems aimed at improving the management of grazing dairy herds.