Optimal Stocking Rates Research Articles

Mason bees and honey bees synergistically enhance fruit set in sweet cherry orchards

AbstractMason bees (Osmia spp.) are efficient fruit tree pollinators that can be encouraged to occupy and breed in artificial nesting material. In sweet cherry orchards, they are occasionally used as an alternative managed pollinator as a replacement for or in addition to honey bees (Apis mellifera). Yet, the lack of practical guidelines on management practices, for example optimal stocking rates, for both mason bee nesting material and honey bees might compromise pollination service provision. In this study, we assessed the relationship between stocking rates (honey bee hives and mason bee nesting material) and the abundance of honey bees and mason bees in 17 sweet cherry (Prunus avium) orchards in Central Germany. We furthermore performed a pollination experiment to explore the interactive effect of mason bees and honey bees on sweet cherry fruit set. In the orchards, both honey bee and mason bee abundance increased with increasing stocking rates of hives or nesting material, respectively. Honey bee abundance increased linearly with stocking rates. In contrast, mason bee abundance asymptoted at 2–3 nesting boxes per ha, beyond which more boxes resulted in little increase in visitation rate. Our pollination experiment demonstrated that orchards were pollen limited, with only 28% of insect‐pollinated flowers setting fruit versus 39% of optimally hand‐pollinated flowers. Honey bees and mason bees enhanced sweet cherry fruit set, but only when both were present and not when either was present alone in an orchard. Our findings demonstrate that offering nesting material for mason bees and employing honey bee hives can enhance bee abundance in sweet cherry orchards. By increasing honey bee abundance in combination with enhanced mason bee abundance, farmers can substantially boost fruit set and potentially sweet cherry yield. To enhance pollination services, farmers should consider the benefits of increasing pollinator biodiversity as an immediate benefit to improve crop yields.

114 Evaluation of Assertions from Educational, Outreach and Engagement Programs in Pasture-Based Livestock Systems

Abstract Assertions about grazing management and grazing systems should be evaluated based on the scientific literature. Prior assumptions can limit our ability to achieve constructive dialogue regarding the merits of various stocking methods. These include the assumption that rotational stocking is inherently superior to continuous stocking, regardless of the nature of the overall grazing system, and the presumption that continuous stocking implies overgrazing. We revisited assertions about grazing management in general, but more specifically the choice of the stocking method, and considered their merit in the context of evidence from the literature, including a chapter titled Prescribed Grazing on Pasturelands from a National Resource Conservation Service (NRCS) literature synthesis published in 2012. We framed those assertions in the form of questions. The questions were: a) Does choice of rotational stocking ensure well-managed pastures?, b) Does rotational stocking result in greater accumulation of soil carbon than continuous stocking?, c) Does rotational stocking increase pasture productivity and optimal stocking rate compared with continuous stocking?, d) Does forage nutritive value and individual animal performance increase in rotational versus continuous stocking?, and e) Do pastures “look better” in rotational versus continuous stocking?. The objectives were to consider whether these often-stated assertions about grazing management were supported, refuted, or simply not adequately assessed by the body of scientific evidence. It is important to recognize that choice of stocking method is only one element of grazing management and grazing management is only one element of a grazing system. Thus, stocking method is “one piece of a very large pie”. Additionally, stocking rate (grazing intensity) is a separate and independent grazing management choice from stocking method, such that both rotationally and continuously stocked pastures can be understocked, overstocked, or optimally stocked. It is unfortunate that choice of stocking method dominates discussions of improving grazing management to the expense of other issues, when in fact intensity of grazing has been shown conclusively to be the most important determinant of a wide array of soil, plant, animal, and ecosystem responses. We have observed that terminology such us regenerative grazing, holistic planned grazing, adaptative multipaddock grazing, management intensive grazing, high intensity low frequency grazing, and others, arise frequently and can dominate discussions in the realm of education, outreach and engagement programs in pasture-based livestock systems. These words/themes lack clear definition, and this lack of specificity may promote misconceptions, thus hindering the opportunity for critical thinking and ultimately the advancement and improvement of grazing systems. Educational efforts in pasture management should strive to remain relevant by focusing on experimental evidence. Local (i.e., state or county level) outreach and engagement programs are challenged with providing timely and specific information with implementable guidelines based on frequent observations at the landscape and farm levels.

Effect of Stocking Density on Culture Efficiency and Physiological Indicators of Largemouth Bass (Micropterus salmoides) under Recirculating Water Conditions in Land-Based Round Ponds

To identify the optimal stocking rate of Micropterus salmoides culture in a land-based round pond recirculating aquaculture system, five stocking densities were tested, i.e., D1–D5 with 60, 70, 80, 90, and 100 fish/m2, respectively. The water temperature of the experimental pond was 20.0–26.5°C. The effects of stocking density on culture productivity and physiological indexes of M. salmoides (initial body weight 50.83 ± 7.28 g) were examined. The D1 and D5 treatments exhibited significantly improved growth performance. The population weight gain in the D5 treatment was the highest, which increased by 63.73%, 52.82%, 60.93%, and 45.08%, compared with groups D1–D4 ( P < 0.05 , each), and the feed conversion ratio was the lowest, which was decreased by 5.65%, 12.03%, 26.42%, and 21.48% compared with groups D1–D4. The levels of crude protein, essential amino acids, and total free amino acids in muscle tissue of group D3 were higher than those in the other groups. Stocking density did not differ significantly on muscle fatty acid composition P > 0.05 , each). The activities of serum AKP and LZM and liver SOD, AKP, and LZM in group D5 were significantly higher than those in the other groups. Thus, 100 fish/m2 was the optimal stocking density of M. salmoides at a size stage of 50.83∼130.13 g in the circulating water of land-based round ponds.

Optimal sheep stocking rates for broad-acre farm businesses in Western Australia: a review

Sheep stocking rate influences farm profit significantly; however determining the optimal stocking rate is a difficult task. In this paper, we address this challenge through three main steps. First, we review the definition of stocking rate; second, we examine prior research relevant to the review topic and highlight the factors that need to be considered when determining the optimal stocking rate; and third, we make recommendations for improvements in research on establishing the optimal sheep stocking rate. Inconsistency in the definition of stocking rate can lead to miscommunication among researchers, advisers and farmers. If 10 dry sheep equivalents (DSE)/ha is optimal for one flock, it may not be optimal for another flock because the DSE measure does not fully capture the nuances of different patterns of nutritional requirements among sheep classes and feed availabilities and their respective prices and costs. The optimal stocking rate occurs when the marginal economic benefit of an additional animal equals its marginal cost. Determining this point requires an understanding of the quantity and quality of feed available throughout the year, the optimal liveweight profile throughout the year, the impact of seasonal variation, the impact of labour availability, the cost of alternative feeds, prices of livestock and livestock products, the risk preferences of the farmer, and any emission policies relating to greenhouse gases. Farmers tend to use their own judgement to set their stocking rates, with the aim of maximising utility. However, the complexities listed make it a challenging task. Thus, researchers have used various simulation and programming models to aid decision-making over optimal stocking rates, but most farmers continue to rely on their own personal judgement. Moreover, often a focus of this modelling is for sheep systems in eastern Australia. Generalising this research across Australia is difficult due to differences in climatic conditions and markets across Australia. Often farmers are unaware of the profits they are foregoing when choosing either an overly conservative or excessive stocking rate. Our research has shown that foregone income of up to AUD50 per hectare can occur when a stocking rate 30% below or above the optimum is selected. Thus, despite the complexities that underpin the stocking rate decision, we believe that there are potential rewards from further research on the optimisation of stocking rates.

Productivity, Profitability and Nitrogen Utilisation Efficiency of Two Pasture-Based Milk Production Systems Differing in the Milking Frequency and Feeding Level

The aim of this study was to model the productivity, profitability and the nitrogen (N) utilisation efficiency (NUE) of two spring-calving pasture-based milk production systems differing in milking frequency and intensification levels in New Zealand. For this purpose, physical performance data from a low-intensity production system where cows were milked once per day (OAD-LI) and from a high-intensity production system where cows were milked twice per day (TAD-HI) were employed. OAD-LI cows were milked once-daily with a stocking rate (SR) of 2.1 cows/ha and fed diets with low supplementation (304 kg pasture silage/cow) with applications of 134 kg N fertiliser/ha and TAD-HI cows were milked twice-daily with a SR of 2.8 cows/ha and fed diets of higher supplementation (429 kg pasture silage and 1695 kg concentrate/cow) with applications of 87 kg N fertiliser/ha. The Moorepark Dairy System Model was used to evaluate production, economic performance and N balance on an annual basis. Despite the higher feed costs of TAD-HI as more supplementation was utilised, profitability per hectare was 16% higher because more cows were milked with a higher milk yield per cow (milking frequency) when compared to OAD-LI. At the cow level, the NUE was higher in TAD-HI (30% vs. 27%) reflecting the better balanced diet for energy and crude protein and higher milk yields as a result of milking frequency. At the farm scale the NUE was higher (38% vs. 26%) in the TAD-HI due to the losses associated with the imported feed being excluded and higher N captured in milk. These results suggest that milking frequency, the use of feed supplementation and application of N fertiliser as management tools on grazing dairy systems affect productivity, profitability and N balance. Further studies are required to find optimal stocking rates in combination with the use of supplementary feed and N fertiliser application that maximize milk production and profitability for OAD and TAD milking production systems but minimize N losses.

Environmental impact of primary beef production chain in Colombia: Carbon footprint, non-renewable energy and land use using Life Cycle Assessment

In Colombia, the beef production chain accounts for approximately 11.6 million cattle heads and annually produces 933 million kg of the beef carcass. There are no life cycle assessment (LCA) studies that have evaluated the environmental performance of Colombian beef systems. The present study aimed to estimate the carbon footprint (CF), non-renewable energy use, and land use of 251 cow-calf and 275 fattening farms in Colombia. The study also aimed to identify the main hotspots of adverse environmental impacts and propose possible mitigation options and their cost-effectiveness. The impact categories were estimated using the 2006 IPCC and the 2019 Refinement to 2006 IPCC guidelines, databases, and locally estimated emission factors. The functional units used were 1 kg fat and protein corrected milk (FPCM) and 1 kg live weight gain (LWG), leaving the farm gate. Three methods of allocating environmental burdens to meat and milk products were applied: economic, energy, and mass allocation. The adoption of improved pastures was considered a mitigation measure, and an economic assessment was performed to estimate the relative cost-effectiveness of its establishment. A principal component multivariate analysis and a Hierarchical Clustering on Principal Components were performed. The economic allocation method assigned a greater environmental burden to meat (83%), followed by energy content (80%) and mass production (73%). The largest sources of GHG emissions were enteric fermentation and manure deposited on pasture. Both cow-calf and fattening systems had a cluster of farms with better productivity, pasture and cattle management practices, and environmental performance. The CF for meat could be reduced by 33 to 56% for cow-calf and 21 to 25% for fattening farms, by adopting improved pastures. Therefore, our results suggest that GHG emissions can be reduced by adopting improved pastures, better agricultural management practices, efficient fertilizer usage, using the optimal stocking rate, and increasing productivity.

THE EFFECTS OF STOCKING DENSITY ON THE PERFORMANCE OF BROILER CHICKENS

THREE trials were conducted to determine the optimum stocking density for broiler chickens raised in a tropical environment In Trial 1, 100,67, 50,40, 34 and 29 birds were placed in duplicates in each pen with an area of 3.72 M2 to give stocking densities of 0.037, 0.056, 0.074, 0.093, 0.10 and 0 128 M2 per bird respectively. In Trial 2, stocking densities of 0.046, 0056, 0.064, 0.074, 0.083 and 0.093 M2 per bird were compared. Trial 3 involved studying the effects of providing equal feeder space (5cm/bird) or equal number of similar sized feeders (2 feeders per pen) when birds were stocked at floor spaces of 0.056, 0.064, 0.74, 0.083 and 0.093 sq meter per bird. Results showed that weight gain and feed consumption decreased, while total meat yield and net income per unit area increased, with increase in stocking rates. Feed efficiency, mortality and carcass dressing percentages were not significantly affected by the stocking rates. The effects of stocking densities on the performance of the birds were not altered by equalizing the feeder space per bird or by providing equal number of feeders per unit space. Management problems in terms of wetness of litter, feeding and watering were encountered with stocking densities of 0.037, 0.046 and 0.056 M2/ bird. Stocking rates of 0.083, 0.093, 0.10 and 0.128 M2 were uneconomic and did not produce superior performances to stocking densities of 0.064 or 0.074 M2/bird. On the basis of the results, floor spaces of 0.064 or 0.074 M2 per bird may be recommended as the optimum for broiler chickens raised in the tropics. The feeder space at these optimum stocking rates need not be more than 5cm per bird.

Effect of stocking rate on Rhodes grass-stylo pasture in the northern guinea savanna zone of Nigeria 2. pasture and sheep. Performance

Mixed pastures of Rhodes grass (Chloris gavana cv. Callide) and Stylo (Stylosanthes guianensis cv. Cook) were evaluated at five stocking rate, 12, 18, 24, 30 and 36 rams/ha over five grazing periods at Shika, Nigeria. The pastures were continuously grazed for 154 to 210 days beginning from late ruiny into dry season (August 10 April). Dry matter yields of stem, leaf, stem + leaf of C. gayana, green material and total herbage declined (P<0.01) as stocking rate and grazing days increased. However, the differences in yields of green material and leaf of C. Igayana at P4 and 30 rams/ha were not significant over the grazing periods. Daily live weight gain (g/headd) was negatively and linearly related to stocking rate. Mean live weight gains at the lowest and highest stocking rates were + 52 and -1 g/head/d in the second grazing season and 62 and 24 g/head/d in the fifth grazing period. Mean live weight production/ha and optimum stocking rates (OSR) in the first, second, third, fourth and fifth grazing periods were: 61.2kg, 17.8 sheep/ha; 155.5kg; 20.4 sheep/ha; 186.2kg, 24.9 sheep/ha; 129.4kg, 21.2 sheep/ha and 200.2kg, 26.0 sheep/ha, respectively. A curvilinear relationship was obtained between live weight gain ha and stocking rate. This study indicated that sheep at the highest and lowest stocking rates will need supplementary feeds after 100 and 128 days, respectively, if grazing commenced just before the end of the rain.

Improving the grassland management strategies of Qinghai-Tibetan Plateau based on Israeli Noy-Meir’s grazing-system dynamics model

Grassland is one of the important natural ecosystems in the which not only play an important ecological role, but is also the main source for livestock production. Because of overgrazing in many of these lands, degradation is extending, which is an overall key issue in China. The Qinghai-Tibetan Plateau, which is often called the roof of the world, is known for its high altitude, low temperature and oxygen content, strong ultraviolet radiation and for its short-term grass growing season. This makes it a vulnerable system, while once damaged, it is very hard to recover. Therefore, it is essential to sustain the eco-function of this alpine grassland system. Reasonable grassland management practice is important for maintaining a sustainable healthy ecosystem. As overgrazing is one of the main causes for degradation of grassland, the proper management should take it account the balance between livestock and vegetation components, and it is essential to select an appropriate stocking rate strategy. Optimal production from pastures is gained only when animal needs and the productive capacity of the pasture are balanced. Stocking rate is usually defined as the number of animals per unit area for a given time period, but is affected by a series of factors, such as animal breeds, animal size and weight, animal performance, animal physiological state, climate environment, resources, grass growing rate and biomass and grass grazing tolerance. Therefore, it is challenging to select the optimal stocking rate, and as so it restricts the planning of reasonable grassland management strategies. In addition, forage biomass and its nutritive quality are dynamic and there is no constant stocking rate that is best for all situations. With the fast development of innovative technology and knowledge, models make possible the attempt to determine proper stocking rates and grazing strategies, while taking in account the balance between livestock and vegetation. But most models are complex while using highly detailed simulations input of many parameters, including grassland, climate, forage, animal physiology and weight, cost and policy, which restrict their use and extension. And so, most farmers are not skilled to use these complicated models in practice. The grassland grazing management model, which was developed by an Israeli researcher, Prof. Imnauel Noy-Meir, is simple, which focusing only two basic processes that determine biomass dynamics, including plant growth and animal consumption of herbage, with a second fundamental management tool, grazing deferment at the start of the green season. The two basic factors are adjusted to be conformed to herbage mass to obtain optimum animal production. This current paper tested Noy-Meir's model in a yak grazing system of Qinghai-Tibetan Plateau. The parameters in Noy-Meir's model in this paper were adjusted, based on published and empirical data from the Qinghai-Tibetan yak grazing system in order to analyze the feasibility of using this model for helpful decision making for improving grazing management strategies in alpine grassland in China. The outcome shows that Noy-Meir's model is easier and helpful for planning grazing practices in Qinghai-Tibetan Plateau grassland. In order to improve the precision of Noy-Meir's model, the parameters still need better adjustment based on the specific pasture conditions. © 2020, Science Press. All right reserved.

Carbon footprint, non-renewable energy and land use of dual-purpose cattle systems in Colombia using a life cycle assessment approach

Dual-purpose cattle systems (DPS) include more than 75% of all dairy cows in Latin America and produce 40% of total milk production. Colombia has the fourth largest cattle herd in Latin America, and DPS account for 39% of the cattle population, and 58% of national milk production. Therefore, focusing on reducing the carbon footprint (CF) of DPS can have a huge contribution on mitigating the environmental impacts of the cattle farming sector. The present study aimed to estimate, based on a farm gate life cycle assessment (LCA) approach, the environmental impact of 1313 dual-purpose farms in Colombia. The study also aimed at identifying the main hotspots of negative environmental impacts and proposing possible mitigation options and their cost-effectiveness. The impact categories such as CF, non-renewable energy use, and land use were estimated using the 2019 Refinement to 2006 IPCC, databases, and locally estimated emission factors. Three methods of allocating environmental burdens to meat and milk products were applied. A principal component multivariate analysis (PCA) and a Hierarchical Clustering on Principal Components (HCPC) were performed. The largest source of greenhouse gas (GHG) in dual-purpose cattle systems comes directly from enteric fermentation, and manure deposited on pasture. The proportion of environmental burdens allocated to meat differed, with the economic method assigning the greater burden (36%), followed by energy content (30%) and mass production (13%). Four farms clusters and two production strategies were identified, a more intensive strategy with high proportion of improved pastures and higher fertilizer application rates (Clusters 1 and 2), and a more extensive with low input of fertilizers and grazing on natural pastures (Clusters 3 and 4). The CF values ranged between 2.1 and 4.2 CO2-eq per kg fat and protein corrected milk (FPCM) and between 9.0 and 18.3 CO2-eq per kg meat among clusters. CF, land use, and non-renewable energy use were lowest for clusters 1 and 3. Concerning cost-effectiveness, the adoption of improved pastures is a negative-cost measure and a promising climate change mitigation option. Overall, the CF could be reduced by around 25 to 48% for milk and meat. Therefore, our results suggest that it is possible to reduce GHG emissions by adopting improved pastures, better agricultural management practices, efficient fertilizer usage, and using the optimal stocking rate. It is expected that these reductions can be achieved with at negative costs.

Multidecadal directional shift in shortgrass stocking rates

Bement (1969) developed a stocking rate (SR) guide for yearling cattle grazing shortgrass steppe based on relationships among average daily weight gain (ADG, kg · d−1), beef production per hectare (BP, kg · ha−1), and stocking rate (animal unit days, AUD · ha−1) measured in long-term grazing experiments conducted from 1940 to 1963. These analyses identified an optimal biophysical SR of 13.5 AUD · ha−1. Here, we 1) examine modern era (2000−2018) SR results from these same long-term grazing experiments to determine if there has been a shift in the optimal biophysical SR and 2) assess the influence of drought (< 75% of normal precipitation) on the optimal biophysical SR. For all years in the modern era, the optimal SR occurred at 23.2 AUD · ha−1, 72% higher than the value reported by Bement (1969). For the 3 drought yr, the optimum SR was 14.2 AUD · ha−1, which still exceeded the optimal SR by Bement (1969). Our results show the capacity of this shortgrass steppe rangeland to produce livestock weight gains has increased substantially between the Bement and modern eras. This multidecadal directional shift to a higher optimum biophysical SR is likely driven by two nonmutually exclusive factors. First, the plant community changed from dominance by a C4 shortgrass (Bouteloua gracilis) in the Bement era to codominance with a more productive C3 midgrass (Pascopyrum smithii) in the modern era. This change has resulted in pasture-level forage production increasing notably between the two eras. Second, the entry weights and genetic growth potential of yearling steers increased over the 8 decades and may have influenced the efficiency of weight gain for a given amount of forage consumed. Our findings provide guidance for incorporating flexible optimum SR in nondrought and drought years for adaptive grazing management strategies.

Stocking rate impacts performance and economics of grazing beef steers on mixed-grass prairies of the Southern Great Plains.

Stocking rate is a fundamental management factor that has major impacts on animal performance, profitability, and long-term sustainability of native range ecosystems. This research was conducted to determine the effects of stocking rate on performance and economics of growing steers grazing a mixed-grass prairie on a rolling upland red shale ecological site at the Marvin Klemme Range Research Station (35° 25′ N 99° 3′ W). The recommended sustainable stocking rate at this location is suggested to be 25 animal unit days (AUD)/ha. Steers [n = 836, initial body weight (BW) ± SD = 216 ± 11.7 kg] grazed at seven stocking rates ranging from 4.13 ha/steer to 1.83 ha/steer over a 7-yr period, from 1990 to 1996, with year considered the random replication. During the experimental period, overall climatic conditions were favorable for forage production with average growing season precipitation of 118% of the long-term average over the 7-yr experiment, and only 1 yr (1994 with only 57% of the long-term average) with growing season precipitation substantially less than the long-term average. Over the entire summer grazing season, average daily gain (ADG) decreased linearly (P < 0.01) with increasing stocking rate, such that for each additional hectare available per steer ADG increased by 0.05 kg/d (R2 = 0.88). Contrary to ADG, BW gain per hectare over the grazing season increased linearly (P < 0.01) with increasing stocking rate, as stocking rate increased from 4.13 ha/steer to 1.83 ha/steer BW gain per hectare doubled from 33.1 kg/ha to 66.8 kg/ha, respectively. With land costs included in the economic analysis, net return per hectare increased linearly (P < 0.01) from $13 [U.S. Dollars [USD]) at the 4.13 ha/steer to $52/ha at the 1.83 ha/steer. For each additional hectare per steer, net return was reduced by $15.80 (USD)/steer and $15.70 (USD)/ha. In favorable climatic conditions, such as during this 7-yr experiment, economically optimal stocking rates can be more than doubled compared with the stocking rate recommended by the United States Department of Agriculture (USDA) Soil Conservation Service. Increasing stocking rates decrease individual animal performance but maximize BW gain per hectare, which leads to the increasing economic returns observed. Research is needed to determine the long-term implications of these stocking rates during unfavorable growing conditions and setting stocking rates based on seasonal weather patterns and extended weather outlook predictions.

Performance of sheep systems grazing perennial pastures. 4. Simulated seasonal variation and long-term production

Choice of sheep-management system alters both production potential and the production risk due to variability in seasonal conditions. This study quantified production and gross margins from systems based on Merino ewes and varying in stocking rate, time of lambing, and the proportion of ewes joined to terminal-breed or Merino rams. Simulation studies were conducted between 1971 and 2011 using the AusFarm decision-support tool for a grazing property in southern New South Wales. Joining between December and May resulted in higher gross margins than in other months because of higher numbers of lambs sold combined with a lower requirement for supplementary feeding. More ewes could be carried per hectare for April joining than February joining to achieve the same midwinter stocking rate and risk of feeding. Self-replacing systems could produce median gross margins similar to those with replacement ewes purchased, but gross margins were sensitive to the cost of replacement ewes. Of the systems compared, February joining to Merino rams produced the lowest gross margins at all stocking rates, but this system also had the lowest variability among years. The advantage of different systems was dependent on seasonal conditions, which altered lamb production and supplementary feeding. The median ranking of systems for gross margin generally did not alter with changes in feed, sheep or wool values. Large increases in gross margins can be achieved through use of terminal-breed rams, optimal stocking rates and time of lambing, but the superiority of any option depended on production system, price assumptions and seasonal conditions.

Valuing Seasonal Climate Forecasts in the Northern Australia Beef Industry

AbstractSeasonal climate forecasts (SCFs) provide opportunities for pastoralists to align production decisions to climatic conditions, as SCFs offer economic value by increasing certainty about future climatic states at decision-making time. Insufficient evidence about the economic value of SCFs was identified as a major factor limiting adoption of SCFs in Australia and abroad. This study examines the value of SCFs to beef production system management in northern Australia by adopting a theoretical probabilistic climate forecast system. Stocking rate decisions in October, before the onset of the wet season, were identified by industry as a key climate sensitive decision. The analysis considered SCF value across economic drivers (steer price in October) and environmental drivers (October pasture availability). A range in forecast value was found ($0–$14 per head) dependent on pasture availability, beef price, and SCF skill. Skillful forecasts of future climate conditions offered little value with medium or high pasture availability, as in these circumstances pastures were rarely overutilized. In contrast, low pasture availability provided conditions for alternative optimal stocking rates and for SCFs to be valuable. Optimal stocking rates under low pasture availability varied the most with climate state (i.e., wet or dry), indicating that producers have more to gain from a skillful SCF at these times. Although the level of pasture availability in October was the major determinant of stocking rate decisions, beef price settings were also found to be important. This analysis provides insights into the potential value of SCFs to extensive beef enterprises and can be used by pastoralists to evaluate the cost benefit of using a SCF in annual management.

Short communication: Milk fat payment affects the relative profitability of Jersey and Holstein-Friesian cows at optimal comparative stocking rate

Choice of stocking rate and breed of cow are 2 strategic decisions that affect the profitability of pasture-based dairy farm businesses. This study sought to analyze the effects of a range of fat and protein prices on the profitability of the Jersey (J) and Holstein-Friesian (HF) breeds at 2 comparative stocking rates (CSR): 80 kg of body weight (BW) per tonne of dry matter (DM) of feed (CSR80), and 100 kg of BW per tonne of DM of feed (CSR100). Data were obtained from a recently published study, and equations constructed to determine the values for fat and protein at which each breed broke even (profit = NZ$0/ha; at time of writing, NZ$1 = US$0.69 or €0.60), returned equal profit, and exceeded the other breed by 1% or 5%. At CSR100 there were few combinations of fat and protein prices for which HF were more profitable than J. At CSR80, J and HF were equally profitable at a fat price of NZ$5.67 ± NZ$0.20 per kilogram, depending on protein price. The study also highlighted the importance of including volume adjustments in milk price calculations when differences in milk composition exist, as the fat price at which the profitability of HF and J were equal was NZ$1.23/kg lower when volume adjustments were included. The recent increase in the value of fat relative to protein favors J. Farmers should consider the medium- to long-term outlook of fat price when evaluating breed choice for their farm system.

Benchmarking technical and economic performance of beef cow-calf to finishing production systems in Ireland

ABSTRACT The objectives of this study were, for cow-calf to finishing production systems, to benchmark animal and financial performance of Irish “national average” farms (AVE) and farms participating in a farm improvement program (IMP) with experimental research farm systems finishing male progeny as steers (RES-S) or bulls (RES-B), and to identify key technical characteristics and financial drivers within these 3 farm categories. Stocking rate, BW output per livestock unit, and carcass weight per day were less on AVE and IMP compared with RES-S/RES-B. Age at first calving was 31.5, 28.9, and 24.0 mo on AVE, IMP, and RES-S/RES-B, respectively. Calving rate and weaning rate were less on AVE than on IMP, and these rates were less on IMP than on RES-S/RES-B. Gross output value and costs per hectare were least on AVE and greatest on RES-S/RES-B. Feed-related costs accounted for 36, 50, 47, and 58% of total costs per hectare on AVE, IMP, RES-S, and RES-B, respectively. Fixed costs accounted for the largest proportion of AVE total costs. Costs of production per kilogram of beef BW equated to $4.73 (€4.04), $2.26 (€1.93), $1.78 (€1.52), and $2.04 (€1.74) on AVE, IMP, RES-S, and RES-B, respectively. A negative net profit per hectare of −$897 (−€767) was achieved by AVE; IMP, RES-S, and RES-B attained net profits per hectare of $208 (€178), $587 (€502), and $405 (€346), respectively. Key performance indicators underpinning profitable beef cow-calf to finishing systems include high individual animal performance (cow reproduction and progeny growth), optimal stocking rates, and low fixed and purchased feed costs.

Dairy cow breed interacts with stocking rate in temperate pasture-based dairy production systems

Economic optimum stocking rates for grazing dairy systems have been defined by accounting for the pasture production potential of the farm [t of dry matter (DM)/ha], the amount of feed imported from outside the farm (t of DM/ha), and the size of the cow (kg). These variables were combined into the comparative stocking rate [CSR; kg of body weight (BW)/t of feed DM available] measure. However, CSR assumes no effect of cow genetics beyond BW, and there is increasing evidence of within-breed differences in residual feed intake and between-breed differences in the gross efficiency with which cows use metabolizable energy for milk production. A multiyear production system experiment was established to determine whether Jersey (J) and Holstein-Friesian (HF) breeds performed similarly at the same CSR. Fifty-nine J cows and 51 HF cows were randomly allocated to 1 of 2 CSR in a 2 × 2 factorial arrangement; systems were designed to have a CSR of either 80 or 100 kg of BW/t of feed DM (J-CSR80, J-CSR100, HF-CSR80, and HF-CSR100 treatment groups). Data were analyzed for consistency of farmlet response over years using ANOVA procedures, with year and farmlet as fixed effects and the interaction of farmlet with year as a random effect. The collated biological data and financial data extracted from a national economic database were used to model the financial performance for the different breed and CSR treatments. On average, annual and individual season pasture DM production was greater for the J farmlets and was less in the CSR100 treatment; however, the effect of CSR was primarily driven by a large decline in pasture DM production in the HF-CSR100 treatment (breed × CSR interaction). This interaction in feed availability resulted in a breed × CSR interaction for the per-cow and per-hectare milk production variables, with HF cows producing more milk and milk components per cow in the CSR80 treatment but the same amount as the J cows in the CSR100 treatment. On a per-hectare basis, HF cows produced the same amount of 4% fat-corrected milk and lactose as J cows in the CSR80 treatment, but less fat; at CSR100, J cows produced more 4% fat-corrected milk, fat, and protein per hectare than HF cows. Our results support a greater gross efficiency for use of metabolizable energy by the J cow; 11% less total metabolizable energy was required to produce 1 kg of fat and protein at a system level. Economic modeling indicated that profitability of both breeds was less at CSR100, but the decline in profitability with increasing stocking rate was much greater in the HF breed. Holstein-Friesian cows were more profitable at CSR80 but were less profitable at CSR100.

Stall and feed bunk stocking rates impact cows' diurnal behavior and activity in automatic milking system farms

Abstract High stall stocking rates have been shown to alter behavior of cows in parlor-milked systems; however, no studies have examined stocking rates for cows milked with automatic milking systems (AMSs). Therefore, we examined the influence of stall and feed bunk overstocking on cows' behavior, displacements, cows' activity, and rumination time in an AMS dairy farm. Each of 2 pens contained 60 cows/pen, 58 free stalls, and 60 headlocks. The effect of stocking rate was examined using 3 treatments applied separately to stalls and feed bunks (100% = 58 stalls or 60 headlocks available for 60 cows; 120% = 50 stalls or 50 headlocks available for 60 cows; and 150% = 40 stalls or 40 headlocks available for 60 cows). Each stall or feed bunk treatment was applied separately for 1 week in a randomized order that was different for each pen, with a 1-week washout period between treatments. Data were collected during the last 2 days of each treatment week. Activity level, time spent ruminating, and the number of displacements were recorded for both feed bunk and lying stall treatments. The number of cows lying, perching, or standing in lying stalls was recorded in response to stall stocking rate treatments, and the number of cows eating or standing at the feed bunk was recorded for feed bunk stocking rate treatments. Statistical analyses were performed using R software (version 3.3.1). Overstocking stalls to 150% reduced the number of cows lying and standing in stalls but increased the number of cows perching in stalls compared with 100% or 120% stocking rates (all P ≤ 0.05). Moreover, overstocking feed bunks to 150% increased the number of cows eating and standing at the feed bunk after delivery of fresh feed compared to 100% or 120% stocking rates (all P ≤ 0.05). Finally, overstocking of either lying stalls or the feed bunk to 150% reduced time spent ruminating and increased cow activity and number of cows displaced from stalls or the feed bunk in comparison with lower stocking rates (all P ≤ 0.05). Thus, changes to cows' behavior when overstocked above 120% in AMS farms may detrimentally affect welfare and health. Producers can use these results to determine optimal stocking rates in AMS dairies, allowing them to optimize facility design and management to maintain good welfare and production without wasting space or resources.

Towards scientifically based management of extensive livestock farming in terms of ecological predator-prey modeling

Grassland production systems have important impact on food supply and in the economy of several countries. In the specific case of Uruguay, located at the Pampa biome, extensive livestock farming represents 80% of the country land use and beef produced in those systems is 90% of the national meat production.Precision livestock production (PLP) or the manipulation of livestock activity taking into account the different components of agroecosystems to improve production has acquired growing importance in recent years within an “ecological intensification” new paradigm. In particular, there has been an increasing interest in applying mathematical modeling to support PLP.Here we develop an integral ecological approach to PLP by modeling the dynamics of the combined grass-animals system as a predator-prey dynamical system or Predator-Prey Grassland Livestock Model (PPGL). The model involves two variables, the grass height and the individual liveweight of animals, as well as the nonlinear interaction between them: animal performance (liveweight) is linked with grass consumption, which depends on forage availability, which in turn is affected by the grazing pressure.To check the PPGL model internal coherence we studied the long-term evolution for its two variables and found oscillations which capture the general observed dynamics both for grass and animal liveweight. From a mathematical point of view this behavior is robust since we show that it corresponds to a frequency locked limit cycle (i.e. forced oscillations).Regarding the quantitative performance of PPGL, the model is able to reproduce known empirical data from extensive grassland farm systems in Uruguay, like the pasture growth rate with a logistic function. Simulations for Basaltic soils of Uruguay resulted in a total production of 3972kg dry matter·ha−1·year−1, with an annual distribution of 20%, 14% 31% and 34% for autumn, winter, spring and summer, respectively. Results for animal liveweight variation, presented a – as expected – high dependence on stocking rate and on initial grass allowance. Winter simulations with low initial grass height (5cm) and high stocking rate (1animal·ha−1) results in a liveweight loss of −0.02kg·animal−1·d−1, whereas spring and summer presented the highest liveweight gain (0.655kg·animal−1·d−1). An annual optimal stocking rate of 0.8Gross Unit·ha−1 for native grassland is supported by short and long-term simulations.

Interaction of ecological and angler processes: experimental stocking in an open access, spatially structured fishery.

Effective management of socioecological systems requires an understanding of the complex interactions between people and the environment. In recreational fisheries, which are prime examples of socioecological systems, anglers are analogous to mobile predators in natural predator-prey systems, and individual fisheries in lakes across a region are analogous to a spatially structured landscape of prey patches. Hence, effective management of recreational fisheries across large spatial scales requires an understanding of the dynamic interactions among ecological density dependent processes, landscape-level characteristics, and angler behaviors. We focused on the stocked component of the open access rainbow trout (Oncorhynchus mykiss) fishery in British Columbia (BC), and we used an experimental approach wherein we manipulated stocking densities in a subset of 34 lakes in which we monitored angler effort, fish abundance, and fish size for up to seven consecutive years. We used an empirically derived relationship between fish abundance and fish size across rainbow trout populations in BC to provide a measure of catch-based fishing quality that accounts for the size-abundance trade off in this system. We replicated our experimental manipulation in two regions known to have different angler populations and broad-scale access costs. We hypothesized that angler effort would respond to variation in stocking density, resulting in spatial heterogeneity in angler effort but homogeneity in catch-based fishing quality within regions. We found that there is an intermediate stocking density for a given lake or region at which angler effort is maximized (i.e., an optimal stocking density), and that this stocking density depends on latent effort and lake accessibility. Furthermore, we found no clear effect of stocking density on our measure of catch-based fishing quality, suggesting that angler effort homogenizes catch-related attributes leading to an eroded relationship between stocking density and catch-based fishing quality at the timescale of annual surveys. We conclude that declines in fishing quality resulting from understocking (due to declines in catch rate with low fish abundance) and overstocking (due to suppressed growth and limited recruitment at high density) give an optimal stocking rate that depends on accessibility and latent effort.