Beef Cattle Pastures Research Articles

188 Prediction of individual grazing beef cattle dry matter intake

Abstract Estimation of individual dry matter intake (DMI) of pastured beef cattle is critical to grassland management, genetic improvement of efficiency, and increasing the sustainability of animal agriculture. Currently, the only way to measure individual DMI of grazing cattle is through expensive, labor intensive, and spatially demanding research protocol. Very few options for assessment of individual DMI of grazing animals exist for cattle producers. We have developed a machine learning approach to predicting individual DMI of pastured beef cattle that requires only body weight (BW), water intake, and open-source climate variables. Training data were collected in Wardensville, WV at the West Virginia University Research, Outreach, and Education Center. Crossbred steers (n = 32) were phenotyped for Residual Feed Intake (RFI) in the barn. Animals were split into four groups of two low RFI and two high RFI. After a grazing acclimation period, animal groups were rotationally grazed concurrently through 0.05 ha plots for 7 d. Daily BW and water intake data were collected throughout the experiment using an RFID-equipped front-end scale and metered waterers. Beginning on d 2, animals were provided a bolus of Cr2O3 (10 g) at 0700 and 1900 h. Beginning on d 5, fecal samples were collected from each animal at 0700 and 1900 h. Samples were analyzed for Cr2O3 content and used in conjunction with forage digestibility from paired clipped samples to generate individual intakes. These data were used as ground truth data to assess model performance. We used our Repeated Measures Random Forest (RMRF) model to predict individual DMI of animals using daily BW, water intake, and climate variables. Intakes estimated by RMRF were compared with intakes estimated by NASEM equations. Our model outperformed NASEM predictions by 70%, indicating that our method achieves better results than the current most efficient approach. Though iterative model improvements will be made (collection of more training data, collection of more diverse training data, and use of first-differenced, moving average, and seasonally adjusted variables), our work demonstrates a novel, efficient method for researchers and producers to more accurately estimate DMI of individual pastured beef cattle.

Fitness benefits of grouping during foraging in beef cattle: Social behaviour or affinity to vegetation resources?

Grouping behaviour in gregarious species expresses a dynamic cost-benefit equilibrium. The balance between costs and benefits differs amongst individuals that were selected to maximize their individual fitness. In environments where resources are limited, benefits of grouping may come at the expense of increased competition over resources. This study aimed to test whether grouping behaviour during foraging in a free-ranging beef cattle herd is a social choice bearing fitness benefits for all participants, or reflects affinity to vegetation resources with possible differentiating fitness benefits. GPS location data were recorded in a herd of 60 beef cows grazing a semi-arid pasture in northern Israel. Pasture vegetation was chemically and spectrally analysed. GPS location data were used to investigate individual and shared foraging locations and the temporal sequence of initiating foraging movement. Co-travel function in ArcPro v3.0 was used to investigate the amount and variability of individual proximity associations and their correlation with fitness. Fitness proxies were conception result (yes/no) and the interval between calving and conception within the cows who conceived. A positive correlation was found between fitness and the individual number of proximity associations, but not with the variability in associations' partners. No significant correlations were found between fitness and vegetation biomass, N content and spectral properties measured by REEVI2 index in foraging locations. Individual sequence of arrival at shared foraging locations and foraging movement initiation sequence were also not correlated with fitness. Vegetation biomass in grouping locations was lower than in individually foraged locations, but no difference was found in N content between individual and shared foraging locations. No differences were found in vegetation biomass and N content between herd foraging locations and random locations, thus no evidence for herd foraging strategy aimed to increase biomass or N consumption was found. No further differences in pasture resources availability, i.e., water, shade, human or predator presence could explain grouping. Circular variance values implied the absence of preferred movement direction. Our results suggest that grouping during foraging is fitness beneficial and is not related to vegetation biomass or N content. Our results further suggest the absence of consistent leading individuals and no significant correlations between foraging movement initiation and fitness. This study provides insights into social and vegetation factors affecting cattle foraging behaviour in constrained pasture, and may allow ranchers to improve grazing management systems. We suggest that further research into pasture characteristics that affect beef cattle pasture location choice is needed.

The cost of doing nothing about a sleeper weed-Nassella neesiana in New Zealand.

Nassella neesiana (Chilean needle grass), an invasive 'sleeper weed' established in sheep and beef pastures in three of New Zealand's sixteen local government regions, has a potential geographic range amounting to 3.96 million hectares spanning all regions except the West Coast. It impacts the productivity, market value and welfare of livestock through its sharp penetrating that cause blindness and the downgrading of wool, hides, and carcasses. In this study we estimate the benefit of preventing its spread as the present value (PV) of local (regional) and national productivity losses that would accrue over 200 years under a 'do nothing' spread scenario. Using a 3% discount rate and two assumed spread rates, 201 and 100 years to 90% occupation of its potential range, we calculate national PV losses of NZ$ 192 million and NZ$ 1,160 million respectively. In a breakeven analysis, these losses, which equate to the national benefits of preventing the spread, justify annual expenditures of NZ$ 5.3 million and NZ$ 34 million respectively. Restricting the analyses to the regions with known infestations (Hawke's Bay, Marlborough, Canterbury) provided much lower estimates of the benefits (ranging from NZ$ 16.8 million to NZ$ 158 million) because spillover benefits from preventing spread to the other susceptible regions are not accounted for. These analyses support a nationally coordinated approach to managing N. neesiana in New Zealand involving surveillance and control measures respectively in the susceptible and infested regions.

Effect of dietary energy source on pregnancy rates and reproductive physiology of pastured beef heifers

Proper production of steroid hormones, such as progesterone (P4), is essential for maintenance of pregnancy. Provision of gluconeogenic substrates from the diet may alter postabsorptive energy supplies and associated hormone signaling in a manner supportive of elevating P4 concentrations. Crossbred Angus heifers (n=27) were balanced for pre-trial bodyweight (BW) and body condition score (BCS), then assigned to isoenergetic diets leveraging starch (ES) or fat (EF) as the primary source of energy (45.7% starch vs 11.5% fat). The heifers were placed on the assigned diets 8 days prior to the initiation of estrous synchronization and continued the diets through the second pregnancy diagnosis, 52 days after the initial insemination. On day 28 post-breeding, pregnancy status was diagnosed via ultrasonography. Measurements of follicle size and number were collected via rectal palpation and ultrasonography on days −10, −8, −4, and day 0 relative to breeding. Blood samples were collected on days −10, 1 through 7, 10, 14, 18, 21, 24, and 28 to analyze plasma for P4 concentrations and placental-associated glycoprotein (PAG) concentrations. Data were analyzed using a linear mixed effects model with a fixed effect for treatment and a random effect for pen. Observations collected over time were analyzed using a repeated measures approach with fixed effects for treatment, time, initial condition, and a random effect for pen. Interactions between treatment and pregnancy status were also tested for PAG and P4 concentrations. No treatment differences were observed in final BCS (P=0.12) and total dry matter intake (DMI; P=0.51), though heifers on the ES treatment tended to reach an increased BW (P=0.10). Although heifers fed ES diets had numerically higher conception rates compared to heifers fed EF diets (71.4% vs. 66.7%), there was no statistically significant difference. Furthermore, there were no significant differences observed among diets in terms of pregnancy outcomes, follicle size, or number. A treatment by pregnancy status interaction was detected for both PAG and P4 concentrations. These results suggest that short-term dietary starch supplementation provided around the time of breeding can result in shifts to reproductive hormone abundance that may be conducive for pregnancy establishment.

Outcomes of a comparison between pastoral and silvopastoral management on beef cattle productivity, animal welfare and pasture depletion in a Mediterranean extensive farm

In spring 2021, 50 growing steers and heifers of the Maremmana breed (average age 321 d and weight 287 kg) were rotationally stocked under two different treatments (silvopastoral and pastoral). The aim was to evaluate the influence of grazing system on cattle growth and welfare, and pasture depletion. The experiment was carried out on a real Mediterranean agrosilvopastoral farm, located in central Italy. To implement rotational grazing, 3.69 ha of temporary grassland were split into six paddocks, three for each treatment. Cattle grazed for one week in one paddock and then were moved to the next one for a total of six weeks corresponding to six grazing periods. The group maintained on the silvopastoral system were allowed to access 3.31 ha of a Turkey oak (Quercus cerris L.) forest. Regarding the average daily gain, a significant interaction was found between the treatment and time. The average daily gain of the animals grazing in the open pasture was 1.20 kg d−1, while that of the cattle grazing in the silvopastoral system was 1.02 kg d−1. Despite the rate of growth being within the expected range for the Maremmana breed, the average daily gain of cattle in the silvopastoral system was significantly lower. One of the possible causes of this difference could be the higher energy requirements of the animals due to the different activity levels. The different management did not affect animal welfare indicators. Indeed, the serum cortisol concentration did not vary between treatments and among sampling times, while the hair cortisol concentration decreased significantly during the experiment for both groups. Regarding pasture health, allowing cattle to graze in the forest reduced pasture depletion because of the lower stocking rate and grazing pressure. Further studies are necessary to increase the knowledge of the role of forests and grazing management in other seasons than spring in extensive agrosilvopastoral systems.

Distribution of Biting Flies Associated with Swine Production Facilities in the Southeastern United States

High populations of pest flies on swine facilities can be detrimental to the animals and producers. The purpose of this study was to identify the distribution pattern and the influence of habitats on distribution of adult biting flies surrounding commercial swine production barns in North Carolina. In this study, fly surveillance was conducted on four swine facilities in Bladen County, North Carolina, U.S.A., from January to October 2019. Biting flies typically associated with livestock were passively collected weekly on sticky traps, which were placed in three concentric circles surrounding swine barns, and then counted and identified. Stable flies [Stomoxys calcitrans (L.); Diptera: Muscidae] were most abundant on swine facilities that were mixed-use with pastured beef cattle. However, swine producers with no pastured cattle should be aware of the potential for stable flies to disperse from off-property larval development sites. Therefore, adult fly management may be necessary if populations reach nuisance levels. Horse and deer fly (Diptera: Tabanidae) captures were not related to trap proximity to water. Differences in horse and deer fly trap captures was likely less of a reflection of differences in potential fly development habitat quality (e.g., water) and more related to adult fly habitat selection.

Innovations in beef breeding - opportunities and problems

Today, the world is experiencing an environmental crisis that is far more dangerous than an economic one. The search for and implementation of innovations that support business should also be consistent with their ecological effect. Raising animals for food originated more than 8,500 years ago, and today meat is part of the diet of most people. Beef farming has reached the stage where implementing digital innovations is a necessity. Unfortunately, when implementing new solutions, the effect on nature is often not evaluated. The environmental impacts may be irreversible or difficult to reverse and may require a much higher cost to remedy. The purpose of the research is to compare the profitability of the implemented solutions, in relation to the environmental problems. The results of the study of some of the most widespread innovations can be systematized in several directions. The implementation of animal control systems on pastures could destroy the natural habitat of wild animals and technical solutions should be sought that reduce these impacts. Tracking the behavior and collecting biometric data from the animals can also be done with non-invasive methods, which will be much more humane and will not disturb the ecological balance in relation to the bees. The main problems are related to the access of wild animals to food and water in control systems by restricting pastures and the use of certain frequencies to transmit the biometric data of the animals and their impact on both farmed animals and bees and other species in the wild. In conclusion, the profitability of beef pasture animal husbandry has the possibility to increase without significant damage to nature, if it is approached relatively individually to each specific regional project in Bulgaria.

A long-term study indicates that tree clearance negatively affects fledgling recruitment to the Blue-fronted Amazon (Amazona aestiva) population.

The Blue-fronted Amazon (Amazona aestiva) is a Neotropical parrot with a large distribution in South America, including areas in Brazil, Bolivia, Argentina and Paraguay. A substantial part of the population of this parrot is concentrated in the Pantanal, a large wetland located in the center of South America. There, the clearing of forest and savannas has occurred through the years to accommodate beef-cattle pasture, and crops. Our objective was to understand the direct and indirect effects of time, availability of forest and savannas, and rainfall over the number of nestlings and fledged young of Blue-fronted Amazons inhabiting the southern Pantanal. We surveyed their nests from 1997 to 2018 and counted the number of nestlings produced and the number of fledglings capable to leave the nest in each year. Additionally, we used available data on the area covered by arboreal vegetation, and rainfall data collected at a Meteorological Station located in a central area of the study, as predictors of the numbers of nestlings and fledglings produced every year. Then, we applied structural equation modeling to examine both the direct and indirect effects of time, arboreal habitat availability, and annual cumulative rainfall on the number of nestlings and fledgling per nest. Finally, we estimated the long-term trend of the number of fledglings per nest as a surrogate to the populational trend of Blue-fronted Amazon. We found that none of the variables in our model explained the number of nestlings in nests, but the number of nestlings and the arboreal habitat availability directly and positively affected the number of fledglings. Time indirectly and negatively affected the number of fledglings per nest, whereas rainfall affected it indirectly positively. Additionally, we detected a concerning decrease of about 30% of the fledglings during the 22-years study, which could lead to a change in the species conservational status.

136 Application of Ear-attached Sensor Technology (CowManager) to Detect Estrus in a Commercial Beef Cow AI Program

Abstract The CowManager (Agis, Harmelen, the Netherlands) ear sensor technology was developed for dairy cows in confinement and has recently been adopted for pastured beef cows. The sensors fit around the ‘840’ RFID button and houses a 3-dimensional accelerometer that registers movement of the cow’s ear. Each sensor stores up to 7 d of internal data at a time and is transmitted by solar powered routers in the pasture. The objective was to determine the effectiveness of the CowManager system’s estrus detection (ED) feature in beef cows during estrous synchronization (ES), AI, and during exposure to bulls for 60 d. Fifty 6-8 yr multiparous commercial Angus-crossbred cows with calves, were fitted with CowManager ear sensors for 14 d to allow for acclimation. Cows then underwent ES using a 6-d CO-Synch + controlled internal drug release (CIDR) protocol with AI at 72 h post CIDR + prostaglandin F2α with sexed female semen. Estrus detection was determined using breeding patches (Estrotect™, Rockway Inc., Spring Valley, WI), with estrus classified as greater than 50% of color rubbed off, and CowManager sensors with a notification to a smartphone and/or computer. The CowManager sensors were effective in determining estrus in 92% (46/50) of the synchronized cows, and the first service conception rate was 74% (37/50). CowManager sensors detected 100% (37/37), and ESTROTECT patches detected 91% (34/37) of the cows in estrus that conceived by AI. During bull exposure, CowManager detected 100% (13/13) of estrus and the natural breeding dates were confirmed by ultrasound fetal aging. ESTROTECT patches were not used during exposure to bulls. However, CowManager detected 5 of the AI pregnant cows as in estrus during the exposure to bulls. CowManager’s ED feature was highly effective in determining estrus for beef cattle and was similar to breeding patches for ED.

Effect of Protracted Free-Choice Chlortetracycline-Medicated Mineral for Anaplasmosis Control on Escherichia coli Chlortetracycline Resistance Profile from Pastured Beef Cattle.

Anaplasmosis is an economically-significant, hemolytic, tick-borne disease of cattle caused by Anaplasma marginale which can cause clinical anemia and death. Current control options are limited, and FDA-approved antimicrobial control options do not have a defined duration of use. A practical and routinely used anaplasmosis control method involves feeding free-choice chlortetracycline (CTC)-medicated mineral to pastured cattle for several months. Constant antimicrobial use poses the risk of expediting the development and dissemination of antimicrobial resistance in off-target commensal bacteria in the bovine gastrointestinal tract. The objective of this study was to determine the CTC-susceptibility of Escherichia coli isolated from anaplasmosis endemic beef cattle herds provided different FDA-approved free-choice CTC-medicated mineral formulations, all intended to provide cattle a dosage of 0.5 to 2.0 mg CTC/lb bodyweight per day. A closed-herd, comprised of Hereford-Angus cows, naturally endemic for anaplasmosis, were grazed in five different pastures with one herd serving as an untreated control group. The other cattle herds were randomly assigned one of four FDA-approved CTC-medicated mineral formulations (700, 5000, 6000, and 8000 g CTC/ton) labeled for “the control of active anaplasmosis” and provided their respective CTC-medicated mineral formulation for five consecutive months. Fecal samples were collected monthly from a subset of cows (n = 6 or 10) per pasture. Fecal samples were cultured for E. coli isolates and the minimal inhibitory concentration of CTC was determined. Baseline CTC-susceptibility of E. coli was variable among all treatment and control groups. The susceptibility of E. coli isolates was significantly different between study herds over the treatment period (p = 0.0037 across time and 0.009 at the final sampling time). The interaction between study herds and treatment period was not significant (p = 0.075).

Forage characteristics and beef cattle production in perennial pastures of BRS Paiaguás and BRS Piatã in integrated crop livestock system

The integrated crop-livestock system is highlighted in Brazilian agriculture, in which the synergism between the components can increase productivity and animal performance. Forage is one of the most important components because it is the basis of animal feed. Thus, the objective of the study was to evaluate the beef cattle production and pastures characteristics of Urochloa brizantha ‘BRS Piatã’ and ‘BRS Paiaguás’, under continuous grazing in an integrated crop livestock system. The experiment was conducted in west of Sao Paulo State, in a randomized complete block design with two treatments and three replicates, from October 2018 to June 2019. The treatments were 3-year-old pastures of BRS Piatã and Paiaguás, in an integrated crop livestock system with perennial pasture and soybean. Nellore steers (14 ± 2 months old and 244 ± 13 kg initial weight) were used. The grazing method adopted was a continuous stocking with a variable rate to maintain a pasture height of 30 cm. Herbage mass was 5716 and 5480 kg dry matter ha-1 for Piatã and Paiaguás, respectively. The crude protein, neutral detergent fiber, and acid detergent fiber were similar between the two cultivars. The leaf blade mass of BRS Piatã was greater than that of BRS Paiaguás in summer. Animal performance was similar between treatments, with average daily gain of 0.901 and 0.822 kg day-1 and weight gain per area of 888 and 865 kg ha-1 in Piatã and Paiaguás, respectively. The BRS Piatã and BRS Paiaguás grasses are indicated for use in perennial pastures in integrated crop livestock systems.

Economic incentives for preserving biodiverse semi-natural pastures with calves from dairy cows

Economical profitability of pasture-based beef production is necessary for continued maintenance of semi-natural pastures. In a situation of decreased cattle stocks, there is a potential to castrate male calves from dairy cows and raise them as grazing steers instead of intact bulls reared indoors, which is the common way in the Nordic countries. We examined the profitability in model enterprises with either grazing steers or indoor bulls. Within the two genders (steer and bull), there were animals of two breed types (pure dairy breed and dairy × beef crossbreed), which were divided into an intensive or extensive production system. The intensive steer system had one summer on grass and slaughter at 21 months of age whereas the extensive steer system had two summers on grass and slaughter at 28 months of age. All bulls were reared indoors and slaughtered at 15 or 18 months of age. The profitability was calculated as contribution margin (CM; Σ revenues – Σ variable costs) in three different herd sizes (50, 100 and 150 slaughtered animals per year) and in three different regions in Sweden (the southern forest districts Gsk, the southern plain districts Gns, and the lower parts of the northern Nn). In the basic calculation, CM for all steers in large herds with 150 slaughtered animals per year was above zero for all cases in Gns, and for one case in Nn and in Gsk respectively. However, all steer cases had lower CM than the comparable bull system in the basic calculation. Sensitivity analyses demonstrate several possible ways of increasing the competitiveness of the grazing steers, compared to the bulls. Utilization of buildings without opportunity cost resulted in a CM above zero for all cases. Increasing the proportion of semi-natural pastures rendering high agri-environmental payment and support was another effective mean. Decreasing the winter feed cost and labour demand on pasture reduced the costs, whereas producing premium-price certified pasture beef increased the revenue, all measures further contributing to an improved profitability. Pasture-based beef production from dairy-born steers can be economically viable, especially in large herds and with extensive production systems. Thereby, we conclude this system to has a potential to graze large areas of semi-natural pastures and thereby conserve their biodiversity and cultural values.

Bioeconomic evaluation of feedings strategies in the yearling beef cattle system in Mozambique

The application of feeding strategies (FS) to meet nutrient requirements of beef cattle grazing on native pastures during the dry season, are required to improve the productivity of production systems in tropical regions. The objective of this study was to evaluate the bioeconomic effects of different FSs applied to yearling bulls in Mozambique, using modeling and simulations as tools to support decision making. A simple deterministic simulation model was developed, assuming initial body weight (120 kg), average daily gain (ADG), feedstuffs, and production costs as inputs. FSs were simulated for a total of 120 days within four ADG systems: 0.000 kg (S000), 0.200 kg (S200), 0.400 kg (S400), and 0.600 kg/d (S600), and three diets were simulated for the positive and maintenance ADG systems, totaling 12 FS. The effects of 12 FS combinations were analyzed and a sensitivity analysis was performed. The effect of the change in the inputs of the model (feedstuffs purchase and calf purchase price) showed the sensitivity of the model to economic parameters (Gross Margin and Net Profit). The negative ADG (-0.200 kg) system (S-200) had the highest labor cost. Corn bran, considering its availability and low cost in the studied region, is a promising feedstuff for concentrates. Effective operational cost (EOC) was higher than 99% in all FSs. S-200, S000, and FS5 within the S200 system resulted in negative net profit (NP) values. Net profit proportionally increased as ADG increased. FS12 (Hyparrhenia rufa, corn bran, and Sesbania sesban) of S600 promoted the highest ratio (NP/total operation cost) (0.48), and consequently, the highest profitability (32.37%). In general, the simulation model shows that, in native and communal pasture beef production systems in regions of Africa with similar production conditions, the productivity of yearling beef cattle during the dry season may be improved by applying feeding strategies.

Face Fly (Diptera: Muscidae)—Biology, Pest Status, Current Management Prospects, and Research Needs

AbstractNative to Europe and Central Asia, face flies (Musca autumnalis De Geer, Diptera: Muscidae) were unintentionally introduced into North America and became pests of pastured beef cattle, dairy cattle, and horses. Female and male flies use their sponging proboscis with prestomal teeth to feed around moist, mucus membranes of an animal’s face and other body parts. While feeding, face flies agitate livestock and elicit defensive behaviors (e.g., ear flapping, head shaking and batting, hiding in deep shade, and adjustment of grazing), and they can transmit eye-inhabiting nematodes and pathogenic bacteria that cause pinkeye. Face flies can be partially controlled with feed-through insecticides that prevent development of face fly maggots in fresh cattle dung pats. Adults can be partially controlled with repellents and insecticides applied directly to animals. Trap-out tactics can be effective and may involve sticky traps placed around high animal traffic areas, such as waterers and feeders in pastures, dairy entryways, or wherever else livestock congregate in pastures. A review of the insect biology and life stages, physical and economic damages, surveillance strategies, and management options for the face fly is presented.

Effects of increasing nitrogen levels in Mombasa grass on pasture characteristics, chemical composition, and beef cattle performance in the humid tropics of the Amazon.

Improving beef cattle production in pasture-based systems without expanding agricultural land has been the focus of several studies over the last decades. Nitrogen fertilization is one of the available strategies with high potential to optimize cattle performance in tropical systems. This study aimed to evaluate the effects of increasing nitrogen levels (150, 300, and 450kgha-1 of Nyear-1) in Megathyrsus maximus cv. Mombasa in the humid tropics of the Amazon. The following parameters were evaluated: pasture agronomic characteristics, herbage chemical composition, and beef cattle performance. A total of 24 nine-month-old Nellore bulls with initial mean weight of 173 ± 1.95kg were used for the performance test. The experimental design was a randomized block with three treatments. Herbage mass and leaf mass contents were increased by the highest nitrogen level (P < 0.05). Nitrogen levels elevated the forage accumulation rate, final leaf blade length, and pre-grazing canopy height(P < 0.05). The crude protein content increased at the highest N level (P < 0.05). The neutral detergent fiber and acid detergent fiber contents decreased with increasing N levels. The stocking rate and total weight gain per hectare were higher in bulls grazing pastures fertilized with 450 compared with 150kgha-1 of Nyear-1(P < 0.05). The average daily gain was influenced by N levels (P < 0.05). Nitrogen levels at 300 and 450kg increased animal weight gain and productivity per area by increasing forage yield and improving the chemical composition of Mombasa grass.

Identification of the production system of beef cattle by the stable isotope analysis

Abstract: The objective of this work was to evaluate the potential of the stable isotope technique to characterize beef cattle production systems in tropical conditions. For this, carbon and nitrogen stable isotopes were identified in non-defatted and defatted bovine muscles. A total of 45 cattle were evaluated in three production systems: pasture, conventional feedlot, and young beef bull feedlot (n = 15 per system). Samples from the Trapezius cervicis, Longissimus dorsi, and Semitendinosus muscles were collected to determine the isotopic composition of δ13C and δ15N. The isotopic data of the δ13C and δ15N of non-defatted and defatted muscles were subjected to the principal component analysis (PCA) and to the discriminant analysis (DA). The PCA allowed separating the three production systems based on the results obtained for the non-defatted and defatted muscles. A correct global classification rate of 100% and a cross-validation rate of 100% were obtained with the DA. The carbon and nitrogen isotopic ratio of non-defatted and defatted muscles allows for the precise identification of beef cattle production systems in tropical conditions.

A review of research on the fertiliser and lime requirements of pasture on the eastern coast of the North Island

The soils on the eastern region of the North Island (Wairarapa, Tararua, Hawke’s Bay, Poverty Bay, East Coast) are mainly of the Brown, Pallic, Recent (Sedimentary) and Pumice orders and are most are farmed with sheep and cattle on hill pastures. Several field trials have been carried out to determine the pasture growth requirements for phosphorus (P), sulphur (S), potassium (K), nitrogen (N), lime and molybdenum (Mo) in this region since the 1960s and the results published in various papers. This review considers the results of these studies collectively and in relation to national datasets. Sedimentary and Pumice soils with Olsen P levels of less than 12 µg/mL required annual application of P. Significant pasture production responses to S were measured where initial soil sulphate-S levels were less than 6 ppm. Additional K for sheep and beef pastures was required mainly on Pumice and Brown soils with soil QTK levels of 6 or less. Large pasture DM responses to N were measured in most trials, especially on steep slopes and sunny aspects with low legume content. Lime is needed to maintain soil pH once it decreases to 5.4 on hill soils. Molybdenum deficiency in legumes can occur on sedimentary soils and should be monitored by clover-leaf analysis.

Current and future direction of nitrogen fertiliser use in Australian grazing systems

The nitrogen (N) nutrition of dairy pasture systems in southern Australia has changed from almost total dependence on legumes in the early 1990s through to almost complete reliance on N fertiliser today. Although some tactical N fertiliser is applied to sheep and beef pastures to boost late winter growth, most N fertiliser usage on pastures remains with the dairy industry. Intensification of the farming system, through increased stocking rates and a greater reliance on N fertiliser, has increased N loading, leading to higher potential N losses through volatilisation, leaching and denitrification. With increasing focus on the environmental impact of livestock production, reducing N loading on dairy farms will become increasingly important to the longer-term sustainability of the dairy industry, possibly with the expectation that Australia will join most of the developed countries in regulating N loading in catchments. This paper examines N usage in modern pasture-based dairy systems, the N cycle and loss pathways, and summarises a series of recent modelling studies and component research, investigating options for improving N use efficiency (NUE) and reducing whole-farm N balance. These studies demonstrate that the application of revised practices has the potential to improve NUE, with increasing sophistication of precision technologies playing an important role. This paper discusses the challenge of sustainably intensifying grazing systems with regard to N loading and what approaches exist now or have the potential to decouple the link between production, fertiliser use and environmental impact.

Spatial Distribution of Inorganic Nitrogen in Pastures as Affected by Management, Landscape, and Cattle Locus.

Uneven spatial distribution of soil N in conventionally managed pastures is a function of various biotic and abiotic factors and results in poor land use efficiency. In this study, we measured soil inorganic N (at depths of 0-5, 5-10, and 10-20 cm) in a 50-m grid and specific areas of interest from eight conventionally managed beef pastures (∼17 ha each), four near Eatonton and four near Watkinsville in the southern Piedmont of Georgia, USA, to assess the effects of management, landscape, and cattle locus in spatial distribution of soil inorganic N. Significant spatial autocorrelation was observed in the soil inorganic N indicating that the regions of high inorganic N deposition were near (within 91 m of) one or more pasture equipage (hay, shade, and water). In the Watkinsville pastures, inorganic N was 65% higher within 5 m of shade than the rest of the pastures, down to a 10-cm soil depth. In the Eatonton pastures, inorganic N (0-5 cm) was 22% higher within 30 m of a hay-feeding areas than the rest of the pasture. Cattle locus calculated as cattle density (cow ha yr) was a function of pasture equipage and had a significant positive relationship with soil inorganic N. Landscape parameters (slope and elevation) significantly affected inorganic N distribution; however, the effect was small and was masked by management factors. Our results suggest that strategic placement of pasture equipage (hay, shade, and water) can effectively distribute N where needed in beef pastures, thereby increasing land use efficiency.

Challenges and Opportunities With On-Farm Research: Total and Soluble Reactive Stream Phosphorus Before and After Implementation of a Cattle-Exclusion, Riparian Buffer

Many nutrient mitigation best management practices (BMP) are promoted by state and federal agencies to protect water quality from animal agriculture. The measured effectiveness of these is highly variable in the research literature. Here, we establish pre- and post-BMP monitoring to evaluate the effectiveness of fencing out cattle from the riparian zone on water quality, specifically, phosphorus (P) loads and concentrations. We collected water samples year-round both before and after a cattle exclusion was established at a small mixed dairy and beef cattle pasture where cattle have historically grazed with unrestricted access to first and second order streams, and analyzed for soluble reactive and total P. Immediately after fence construction, we observed a significant reduction in total P in the stream but not in soluble reactive P. We also observed the development of new runoff source areas and short-circuiting of the riparian buffer as well as repeated presence of cows in the fenced-out area, all of which may diminish the potential effectiveness of this practice. Because BMPs will perform uniquely given climate and landscape position and how managers maintain them, we suggest the need for more nuanced guidance for future BMP designs to ensure successful outcomes.