Animal Feed Formulation-Connecting Technologies to Build a Resilient and Sustainable System.

The unprecedented challenges presented by the increase in global population have placed substantial demands on the livestock industry for human nutrition, necessitating heightened animal productivity and leading to an increased demand for natural resources to produce animal feed. Feed producers are leading the charge, consistently refining formulations to adapt to the evolving needs of livestock, driven in part by the cost of over 50% associated with feed production. This paper critically analyses the pressing issues within feed formulation, addressing the requirement for environmentally sustainable practices amidst the challenges of climate change. The exploration extends to how advanced decision support tools can enhance formulation techniques and profitability and contribute to environmental sustainability. Through an in-depth review of current feed formulation technologies, encompassing their applications and limitations, this study aims to enhance the existing knowledge base. Additionally, we examined future trends, highlighting the essential role of connecting technologies to establish a resilient and sustainable system. The emphasis is on the potential of formulation techniques to positively impact the environment and enhance the overall quality and performance of the animals. This paper provides actionable insights to improve animal production by examining feed formulation models and decision support tools. The anticipated outcome is a more informed and sustainable decision-making process, addressing the multifaceted challenges confronted by the livestock industry and making contributions to global efforts in climate change mitigation and environmental stewardship in animal production agriculture.

Climate Spaces and Cliffs: A Novel Bovine Thermodynamic and Mass Balances Model.

The effects of climate change on animals are typically viewed in terms of survivability and wellbeing. In this study, we broaden that purview to include climate impacts on reproductive capability. There are not only climate spaces for daily function, but climate cliffs that represent reproductive failures in the face of climate warming. This alternative focus suggests that climate warming challenges may be more immediate and profound than initially imagined. This research describes a state-of-the-art mechanistic model, Dairy Niche Mapper (DNM), and independent validation tests. Where test data are absent, the calculated results are consistent with expected responses. Simulations of metabolic chamber conditions reveal the local steady-state impacts of climate and animal variables on milk production capacity, metabolic rate, food consumption and water needs. Simulations of a temperature humidity index (THI) show strengths and limitations of that approach. Broader time- and spatial-scale calculations applied in the western and eastern halves of the northern hemisphere identify current and future monthly latitudinal climate change impacts on milk production potential, feed and water needs in dairy cows of different sizes. Dairy Niche Mapper (DNM) was developed from a broadly tested mechanistic microclimate-animal model, Niche Mapper (NM). DNM provides an improved quantitative understanding of the complex nonlinear interactions of climate variation and dairy bovine properties' effects on current and future milk production, feed and water needs for grazing and confinement dairy operations. DNM outputs include feasible activity times, milk production and water and feed needs of different-sized Holstein cows on high-grain (confinement feeding) versus high-forage (grazing feeding) diets at three arbitrary north latitudes, 12°, 30° and 60°, for North and Central America and for Asia. These three latitudes encompass current northern hemisphere bovine production environments and possible future production locations. The greatest impacts of climate change will be in the low elevations in tropical and subtropical regions. Global regions above 30° and below 60° latitude with reliable rainfall will be least affected by current projected levels of climate change. This work provides the basis for computational animal design for guiding agricultural development via breeding programs, genetic engineering, management options including siting or the manipulation of other relevant environmental and animal variables.

Methods, Thermodynamic Applications, and Habitat Implications of Physical and Spectral Properties of Hair and Haircoats in Cattle.

The physical properties (hair diameter, hair length, haircoat depth and haircoat density) and spectral properties (absorptivity, reflectivity, transmissivity) of the hair and haircoat of cattle are inputs to heat and moisture exchange between the skin surface and the surrounding environment, and thus play a critical role in body temperature regulation. Physical and spectral properties of haircoats also play an important role in protecting the skin against penetration of ultraviolet radiation. The focus of this review is to identify accurate and consistent measurement procedures of these properties. Additionally, the paper shows the utilization of the properties on heat exchange models and their implications on voluntary thermoregulation of cattle. To highlight the effects and benefits of haircoat color vis-à-vis solar radiation and its implication on ecological habitation, a brief explanation is provided using polar bears (white haircoat in a cold environment) and black goats in a hot desert environment.

An Outlook on Harnessing Technological Innovative Competence in Sustainably Transforming African Agriculture.

Agricultural value chains worldwide provide essential support to livelihoods, ecosystem services, and the growing bioeconomy. The coronavirus disease 2019 (COVID-19) pandemic slowed down or reversed decades of agricultural growth and exposed the vulnerabilities of farmers and the food insecure in Africa, thus reiterating the need to build resilience, agility, and adaptability for a sustainable agriculture. Existing social, political, environmental, and economic challenges demonstrate that a path to faster sustainable growth is increased productivity through improved input quality, of which technical inputs are a part. This work presents a perspective calling for African innovative competence in technological and methodological applications and solutions as part of the most critical area of a holistic organization for social progress. It finds that while performances of previous agricultural transformation efforts offer insights for future directions, novel pathways fitting to the diversity of situations and contexts on the continent are needed. These may include vertical agriculture in land-constrained regions to grow high-value products, ocean or sea farming in coastal regions, development of multiple-harvesting crops, and self-replicating plants. Developing standards that integrate current scientific methodologies and technologies with indigenous knowledge for agricultural growth and disaster management will bring the complementary benefits of both worlds into optimal development.

Use of Solar Panels for Shade for Holstein Heifers.

Animal Agrivoltaics combines electric energy generation, animal thermal comfort, and sustainable production at the same time. This model of production can foster the sustainable intensification of dairy production in tropical areas where solar irradiance is high and nearly constant throughout the year. In this study, we propose Animal Agrivoltaics as an alternative practice to reduce the heat load and eCH4 emissions from dairy heifers in tropical areas. To attest this hypothesis, (1) the meteorological data and the behavioral and physiological responses of the animals were integrated in order to determine the benefits provided by the shade from the solar panels on the thermoregulation of the dairy heifers, and (2) measurements of the enteric methane emissions were taken to determine the potential of the solar panels to offset the GHG. Seven crossbred Holstein heifers (7/8, Holstein × Gyr) with a mean body weight of 242 kg (SD = 53.5) were evaluated in a paddock shaded with ten modules of solar panels. Miniature temperature loggers were used to record the body surface, skin and vaginal temperatures of the heifers every five minutes. The respiratory rate and the shade-use behavior were also monitored by two observers. These measurements were taken from 08:00 to 17:00 h for 18 consecutive days. After completing the field study, the heifers underwent for assessments of the daily oscillations of eCH4 emission using a flow-through respirometry system. The use of shade by the heifers was progressively increased (p < 0.01) with an increasing level of solar irradiance. Lying and ruminating were more likely (p < 0.01) to occur when the heifers were in the shade, especially when the solar irradiance exceeded 500 W m-2. Between 10:00 and 14:00 h, the heifers benefited from the shade produced by the solar panels, with a reduction of 40% in the radiant heat load. With an increasing intensity of solar irradiance, body surface temperature, skin temperature and respiratory rate of the heifers in the shade were lower (p < 0.01) compared to when they were exposed to the sun. The heifers had a daily methane emission total of 63.5 g per animal-1 or 1.7 kg of CO2-eq. Based on this emission rate and the amount of CO2-eq that was not emitted to the atmosphere due to the electricity generated by solar panels, 4.1 m2 of panels per animal (nominal power = 335 W) would be expected to obtain a net-zero eCH4 emission. Over a period of one year (from September 2018 to August 2019), a set of ten photovoltaic panels used in the study produced 4869.4 kWh of electricity, thereby saving US $970.00 or US $48.00 per m2 of solar panel. Based on the results of this study, it can be concluded that use of Animal Agrivoltaics, in addition to producing electricity, has significant potential benefit in providing better thermal comfort to cattle, as well as offsetting the enteric methane emissions released into the environment. In addition, the system would provide extra income to farmers, as well as a potential source of energy micro-generation.

Economically sustainable shade design for feedlot cattle.

Provision of shade reduces radiant heat load on feedlot cattle, thus reducing demand of water and energy for thermoregulation. While the positive effects of shade on animal welfare are widely known, the literature lacks data on the magnitude of its economic impacts. In this study, we propose the concept of novel shade design to prove that a correctly oriented and dimensioned roof structure, which optimizes shade to be displaced within the pens, motivates cattle to seek shade, protect them from short-wave solar radiation, and is resilient to counteract weather adverse conditions. The beneficial outcome is improvement in animal welfare and productive performance, as well as increments on financial return and sustainability. To attest these benefits, eight hundred B. indicus × Bos taurus bulls were randomly assigned in pens with or without shade from a galvanized steel-roof structure. Performance data (e.g., dry matter intake, body weight gain, feed efficiency and hot carcass weight) and heat stress indicators (e.g., subcutaneous temperature, body-surface temperature, respiratory rate and water intake) were assessed along the study period. The economic outcomes derived from shade implementation were determined using the net present value. Meteorological variables were also monitored every 1 min, and grouped in a thermal comfort index for feedlot cattle, the InComfort Index (InCI). The shade structure efficiently reduced radiant heat load on cattle in pens with shade. According to the classification of the InCI, during very hot days (InCI > 0.6; around noon with mean solar radiation above 800 W m-2 and mean air temperature above 33°C), greater proportion (80%) of animals in shaded pens were using shade. Under such circumstances, cattle in shade had water intake reduced by 3.4 L per animal, body temperature was lower by 5°C, subcutaneous temperature was lower by 1°C and respiration rate was lower by 10 breaths min-1 compared to animals in pens without shade (P = 0.0001). Although dry matter intake was similar (P = 0.6805), cattle in pens with shade had higher average daily gain reflected in a heavier hot carcass weight (8 kg animal-1; P = 0.0002). Considering an initial investment of $90 per animal to build a structure that lasts 15 years, the expected payback time is four finishing cycles (~110 days per cycle). In conclusion, this study confirms that the proposed novel shade design is economically profitable, improves performance, and enhances animal welfare.

A predictive model of equivalent temperature index for dairy cattle (ETIC).

Thermal stress imposed on cows adversely affects health and productivity. Various thermal indices exist in the literature that can be used to assess the level of heat stress on cattle by linking environmental conditions with physiological responses. However, many of these indices either do not incorporate all of the environmental variables or may consider only the main effects of the independent variables without considering the interaction effects. The objective of this study was to develop a thermal index for dairy cattle, referred to as Equivalent Temperature Index for Cattle (ETIC), which incorporates air temperature, relative humidity, air velocity and solar radiation and their interactions. Environmental and physiological data from two studies were pooled together to develop and validate the proposed index. The index (ETIC) expressed in terms of temperature units is derived from equivalent air temperature of relative humidity, air velocity and solar radiation. ETIC heat-stress level thresholds were defined according to the thresholds for temperature-humidity index (THI). The results indicate that the ETIC model predicts the measured physiological responses very well. The coefficient of correlation, R2, for skin temperature, core-body temperature, and respiration rate were 0.79, 0.40, and 0.49, respectively. The ETIC prediction of skin temperatures, core-body temperatures, and respiration rates were better compared to that of three recently developed thermal indices (adjusted THI, heat load index, and comprehensive climate index). The proposed index could be a useful tool to assess thermal environments to ensure animal comfort.

Metabolic heat production and evaporation of poultry.

Accurate measurements of gas exchange between an animal and its environment is critical in determining metabolic heat production and respiratory functions of broilers. Information on non-invasive methods to measure gas exchange of broiler chicks and chickens under uncontrolled environmental conditions is lacking in the literature. The aims of this study were: (1) to develop an indirect calorimetric system including a hood that allows gas exchange for chickens, (2) to measure gas exchange and respiratory functions (respiration rate, ventilation rate, and tidal volume) of broiler chickens weighing greater than 250 g, and (3) to calculate heat production and respiratory evaporation of the birds based on measured gas and vapor exchanges. We conducted two trials. The first trial involved 6 broiler chicks evaluated for 6 days in 6 different schedules (6 × 6 Latin square). The chicks were kept inside a heat exchanger with a continuous air flow of 150 mL min-1. The second trial involved 12 birds evaluated for 12 days in 12 different schedules (12 × 12 Latin square). Metabolic heat production and evaporation were influenced by live weight of chicks, varying between evaluation days (P < 0.05). The respiratory functions (tidal volume, ventilation rate, and respiratory rate) varied between days, and were strongly influenced by live weight of the broilers (P < 0.05).

Tetrahedral node for Transmission-Line Modeling (TLM) applied to Bio-heat Transfer.

Transmission-Line Modeling (TLM) is a numerical method used to solve complex and time-domain bio-heat transfer problems. In TLM, parallelepipeds are used to discretize three-dimensional problems. The drawback in using parallelepiped shapes is that instead of refining only the domain of interest, a large additional domain would also have to be refined, which results in increased computational time and memory space. In this paper, we developed a tetrahedral node for TLM applied to bio-heat transfer that does not have the drawback associated with the parallelepiped node. The model includes heat source, blood perfusion, boundary conditions and initial conditions. The boundary conditions could be adiabatic, temperature, heat flux, or convection. The predicted temperature and heat flux were compared against results from an analytical solution and the results agreed within 2% for a mesh size of 69,941 nodes and a time step of 5ms. The method was further validated against published results of maximum skin-surface temperature difference in a breast with and without tumor and the results agreed within 6%. The published results were obtained from a model that used parallelepiped TLM node. An open source software, TLMBHT, was written using the theory developed herein and is available for download free-of-charge.

Triangular node for Transmission-Line Modeling (TLM) applied to bio-heat transfer.

Transmission-Line Modeling (TLM) is a numerical method used to solve complex and time-domain bio-heat transfer problems. In TLM, rectangles are used to discretize two-dimensional problems. The drawback in using rectangular shapes is that instead of refining only the domain of interest, a large additional domain will also be refined in the x and y axes, which results in increased computational time and memory space. In this paper, we developed a triangular node for TLM applied to bio-heat transfer that does not have the drawback associated with the rectangular nodes. The model includes heat source, blood perfusion (advection), boundary conditions and initial conditions. The boundary conditions could be adiabatic, temperature, heat flux, or convection. A matrix equation for TLM, which simplifies the solution of time-domain problems or solves steady-state problems, was also developed. The predicted results were compared against results obtained from the solution of a simplified two-dimensional problem, and they agreed within 1% for a mesh length of triangular faces of 59µm±9µm (mean±standard deviation) and a time step of 1ms.

Modeling heat loss from the udder of a dairy cow.

A mechanistic model that predicts sensible and latent heat fluxes from the udder of a dairy cow was developed. The prediction of the model was spot validated against measured data from the literature, and the result agreed within 7% of the measured value for the same ambient temperature. A dairy cow can lose a significant amount of heat (388W/m(2)) from the udder. This suggests that the udder could be considered as a heat sink. The temperature profile through the udder tissue (core to skin) approached the core temperature for an air temperature ≥37°C whereas the profile decreased linearly from the core to skin surface for an air temperature less than 37°C. Sensible heat loss was dominant when ambient air temperature was less than 37.5°C but latent heat loss was greater than sensible heat loss when air temperature was ≥37.5°C. The udder could lose a total (sensible + latent) heat flux of 338W/m(2) at an ambient temperature of 35°C and blood-flow rate of 3.2×10(-3)m(3)/(sm(3) tissue). The results of this study suggests that, in time of heat stress, a dairy cow could be cooled by cooling the udder only (e.g., using an evaporative cooling jacket).

Thermal equilibrium of goats.

The effects of air temperature and relative humidity on thermal equilibrium of goats in a tropical region was evaluated. Nine non-pregnant Anglo Nubian nanny goats were used in the study. An indirect calorimeter was designed and developed to measure oxygen consumption, carbon dioxide production, methane production and water vapour pressure of the air exhaled from goats. Physiological parameters: rectal temperature, skin temperature, hair-coat temperature, expired air temperature and respiratory rate and volume as well as environmental parameters: air temperature, relative humidity and mean radiant temperature were measured. The results show that respiratory and volume rates and latent heat loss did not change significantly for air temperature between 22 and 26°C. In this temperature range, metabolic heat was lost mainly by convection and long-wave radiation. For temperature greater than 30°C, the goats maintained thermal equilibrium mainly by evaporative heat loss. At the higher air temperature, the respiratory and ventilation rates as well as body temperatures were significantly elevated. It can be concluded that for Anglo Nubian goats, the upper limit of air temperature for comfort is around 26°C when the goats are protected from direct solar radiation.

Modeling conductive cooling for thermally stressed dairy cows.

Conductive cooling, which is based on direct contact between a cow lying down and a cooled surface (water mattress, or any other heat exchanger embedded under the bedding), allows heat transfer from the cow to the cooled surface, and thus alleviate heat stress of the cow. Conductive cooling is a novel technology that has the potential to reduce the consumption of energy and water in cooling dairy cows compared to some current practices. A three-dimensional conduction model that simulates cooling thermally-stressed dairy cows was developed. The model used a computational fluid dynamics (CFD) method to characterize the air-flow field surrounding the animal model. The flow field was obtained by solving the continuity and the momentum equations. The heat exchange between the animal and the cooled water mattress as well as between the animal and ambient air was determined by solving the energy equation. The relative humidity was characterized using the species transport equation. The conduction 3-D model was validated against experimental temperature data and the agreement was very good (average error is 4.4% and the range is 1.9-8.3%) for a mesh size of 1117202. Sensitivity analyses were conducted between heat losses (sensible and latent) with respect to air temperature, relative humidity, air velocity, and level of wetness of skin surface to determine which of the parameters affect heat flux more than others. Heat flux was more sensitive to air temperature and level of wetness of the skin surface and less sensitive to relative humidity.

Production and physiological responses of heat-stressed lactating dairy cattle to conductive cooling.

The objective of this research was to test the effectiveness of conductive cooling in alleviating heat stress of lactating dairy cows. A conductive cooling system was built with waterbeds (Dual Chamber Cow Waterbeds, Advanced Comfort Technology Inc., Reedsburg, WI) modified to circulate chilled water. The experiment lasted 7 wk. Eight first-lactation Holstein cows producing 34.4±3.7kg/d of milk at 166±28 d in milk were used in the study. Milk yield, dry matter intake (DMI), and rectal temperature were recorded twice daily, and respiration rate was recorded 5 times per day. During wk 1, the cows were not exposed to experimental heat stress or conductive cooling. For the remaining 6 wk, the cows were exposed to heat stress from 0900 to 1700h each day. During these 6 wk, 4 of the 8 cows were cooled with conductive cooling (experimental cows), and the other 4 were not cooled (control cows). The study consisted of 2 thermal environment exposures (temperature-humidity index mean ± standard deviation of 80.7±0.9 and 79.0±1.0) and 2 cooling water temperatures (circulating water through the water mattresses at temperatures of 4.5°C and 10°C). Thus, a total of 4 conductive cooling treatments were tested, with each treatment lasting 1 wk. During wk 6, the experimental and control cows were switched and the temperature-humidity index of 79.0±1.0 with 4.5°C cooling water treatment was repeated. During wk 7, waterbeds were placed directly on concrete stalls without actively cooling the water. Least squares means and P-values for the different treatments were calculated with multivariate mixed models. Conductively cooling the cows with 4.5°C water decreased rectal temperature by 1.0°C, decreased respiration rate by 18 breaths/min, increased milk yield by 5%, and increased DMI by 14% compared with the controls. When the results from the 2 cooling water temperatures (4.5°C and 10°C circulating water) were compared, we found that the rectal temperature from 4.5°C cooling water was 0.3°C lower than the rectal temperature with 10°C cooling water, but the other measurements (respiration rate, milk production, and DMI) did not show a statistically significant difference between the cooling water temperatures. Placing waterbeds on concrete stalls without additional cooling did not have a measurable effect in alleviating the heat stress of the cows.

Thermal biology of domestic animals.

The thermal environment is the most important ecological factor determining the growth, development, and productivity of domestic animals. Routes of energy exchange (sensible heat and latent heat) between animals and their environment are greatly influenced by body weight, fat deposition, hair-coat properties, functional activity, and number of sweat glands, as well as the presence or absence of anatomical respiratory countercurrent heat exchange capability. Differences in these anatomical features across species have led to specialization of heat exchange. Thermal plasticity and degree of acclimation are critical factors determining the ability of animals to respond to environmental change. Increases in productive capability of domestic animals can compromise thermal acclimation and plasticity, requiring greater investments in housing systems that reduce variability of the thermal environment. The combination of steadily increasing metabolic heat production as domestic animal productivity increases and a rising world temperature poses ongoing and future challenges to maintaining health and well-being of domestic animals.

Graded meshes in bio-thermal problems with transmission-line modeling method.

In this study, the transmission-line modeling (TLM) applied to bio-thermal problems was improved by incorporating several novel computational techniques, which include application of graded meshes which resulted in 9 times faster in computational time and uses only a fraction (16%) of the computational resources used by regular meshes in analyzing heat flow through heterogeneous media. Graded meshes, unlike regular meshes, allow heat sources to be modeled in all segments of the mesh. A new boundary condition that considers thermal properties and thus resulting in a more realistic modeling of complex problems is introduced. Also, a new way of calculating an error parameter is introduced. The calculated temperatures between nodes were compared against the results obtained from the literature and agreed within less than 1% difference. It is reasonable, therefore, to conclude that the improved TLM model described herein has great potential in heat transfer of biological systems.