The effect of size and density on the mean retention time of particles in reindeer (Rangifer tarandus).

Particle passage from the reticulorumen (RR) depends on particle density and size. A classic way of assessing these effects is the use of plastic markers of varying density and size that are recovered in the faeces. Here, we report results of an experiment where four fistulated reindeer (Rangifer tarandus, 96 ± 12 kg) were fed two different diets (browse, voluntary dry matter intake [DMI] 70 ± 10 g/kg0.75/d; or a pelleted diet, DMI 124 ± 52 g/kg0.75/d) and dosed via fistula with 8 different particle types combining densities of 1.03, 1.22 and 1.44 g/ml and sizes of 1, 10 and 20 mm. Generally, particles that passed the digestive tract intact (not ruminated) did so relatively early after marker dosing, and therefore had shorter mean retention times (MRT) than ruminated particles. On the higher intake, the overall mean retention time (MRT) of particles was shorter, but this was not an effect of shorter MRT for either intact or ruminated particles, but due to a higher proportion of intact particles at the higher intake. This supports the concept that ruminants do not adjust chewing behaviour depending on intake, but that a lower proportion of digesta is submitted to rumination due to pressure-driven escape from the forestomach at higher gut fills. Compared to cattle (Bos primigenius taurus), muskoxen (Ovibos moschatus) and moose (Alces alces) that had received the same markers, reindeer had a lower proportion of 1 mm particles that passed intact. Our results support the concept that the critical size threshold for particles leaving the ruminant forestomach is dependent on body size. While the results likely do not represent findings peculiar for reindeer, they indicate fundamental mechanisms operating in the forestomach of ruminants.

Review: Endometrial function in pregnancy establishment in cattle.

The endometrium is fundamentally required for successful pregnancy in ruminants and species where the posthatching conceptus undergoes a protracted elongation and peri-implantation phase of pregnancy. Moreover, there are substantial waves of pregnancy loss during this pre- and peri-implantation period of pregnancy the precise source of which has not been clearly defined i.e., the maternal uterine contribution to this loss. Understanding the molecular interactions required for successful pregnancy in cattle will allow us to intervene to support pregnancy success during this vulnerable window. The endometrium contributes to most key developmental milestones of pregnancy establishment, including (1) contributing to the regulation of the oestrus cycle, (2) nourishing the preimplantation conceptus, (3) responding to the conceptus to create a more receptive microenvironment, (4) providing essential biophysical support, and (5) signalling and producing factors which affect the mother systemically. This review will summarise what we currently know about conceptus-maternal interactions as well as identify the gaps in our knowledge that could be filled with newer in vitro model approaches. These include the use of microfluidics, organ-on-a-chip devices, and bioinformatic approaches. This will help maximise food production efficiency (both meat and dairy) and decrease the environmental burden, while enhancing our understanding of the fundamental processes required for successful implantation in cattle.

Review: Maintenance of the ruminant corpus luteum during pregnancy: interferon-tau and beyond.

This manuscript reviews the mechanisms that maintain the corpus luteum (CL) of pregnancy in ruminants. In mammals, ovulation and luteinization of the remaining cells in the CL are due to a surge in Luteinizing Hormone (LH). In cattle, continued secretion of pulses of LH is essential for full development and function of the CL during the estrous cycle (LH pulses), however, the few studies on the CL after d20 of pregnancy do not indicate that LH is essential for maintaining the CL of pregnancy. The first essential step in maintaining the CL of pregnancy in ruminants is overcoming the mechanisms that cause regression of the CL in non-pregnant ruminants (d18-25 in cattle; d13-21 in sheep). These mechanisms have a uterine component involving oxytocin-induced prostaglandin F2α (PGF2A) pulses and a luteal component involving decreased progesterone production and luteal cell death. There is a critical role for embryonic interferon-tau (IFNT) in suppressing the uterine secretion of PGF2A during early pregnancy (d13-21 in sheep; d16-25 in cattle) and preventing luteolysis. There are also effects of IFNT on the expression of interferon-stimulated genes in other tissues including the CL but the physiologic role of these interferon-stimulated genes is not yet clear. After the IFNT period, there is another mechanism that maintains the CL of pregnancy in ruminants since embryonic IFNT is inhibited as attachment occurs and trophoblastic binucleate/giant cells begin secretion of pregnancy-associated glycoproteins. The second mechanism for luteal maintenance has not yet been defined but acts in a local manner (ipsilateral to pregnancy), and remains functional from d25 until just before parturition. The most likely mechanisms mediating later maintenance of the CL of pregnancy are increased uterine blood flow or decreased prostaglandin transporter expression in the utero-ovarian vasculature, preventing PGF2A reaching the CL. Finally, implications of these ideas on pregnancy loss in cattle are explored, highlighting the importance of inappropriate regression of the CL of pregnancy as a mechanism for pregnancy loss in cattle.

Equid Nutritional Physiology and Behavior: An Evolutionary Perspective.

Like other members of the odd-toed ungulates (the perissodactyls), equids once had a higher species diversity in the fossil record than they have today. This is generally explained in comparison to the enormous diversity of bovid ruminants. Theories on putative competitive disadvantages of equids include the use of a single toe as opposed to two toes per leg, the lack of a specific brain cooling (and hence water-saving) mechanism, longer gestation periods that delay reproductive output, and in particular digestive physiology. To date, there is no empirical support for the theory that equids fare better on low-quality forage than ruminants. In contrast to the traditional juxtaposition of hindgut and foregut fermenters, we suggest that it is more insightful to sketch the evolution of equid and ruminant digestive physiology as a case of convergence: both evolved a particularly high chewing efficacy in their respective groups, which facilitates comparatively high feed and hence energy intakes. But because the ruminant system, less based on tooth anatomy but more on a forestomach sorting mechanism, is more effective, equids depend more on high feed intakes than ruminants and may well be more susceptible to feed shortages. Arguably, the most underemphasized characteristic of equids may be that in contrast to many other herbivores including ruminants and coprophageous hindgut fermenters, equids do not use the microbial biomass growing in their gastrointestinal tract. Equids display behavioral and morphophysiological adaptations to high feed intakes, and their cranial anatomy that facilitates the cropping of forage while performing grinding chewing at the same time might be unique. Rather than looking for explanations how equids are better adapted to their present niches than other organisms, considering them remnants of a different morphophysiological solution may be more appropriate.

Could propionate formation be used to reduce enteric methane emission in ruminants?

To meet the increasing demand for meat and milk, the livestock industry has to increase its production. Without improving its efficiency, increased livestock, especially ruminant animals, will worsen the environmental damage, mainly from enteric CH4 emission. Enteric CH4 emission from ruminants not only exacerbates the global greenhouse effect but also reduces feed energy efficiency for the animals. The rumen disposes of metabolic hydrogen ([H]) primarily through methanogenesis and propionate formation. Theoretically, redirecting [H] from methanogenesis to propionate formation to reduce CH4 production could be a promising method for reducing greenhouse gas emission from ruminants, and may also increase animal productivity. However, the feasibility of such a shifting has never been synthetically discussed. Thus, the objectives of this review are to provide a brief overview of the biochemical pathways for disposal of H2 in the rumen, to analyze current feeding strategies that potentially promote propionate formation and their effects on methanogenesis, and to deliberate the challenge and opportunity associated with propionate formation as a sink to store the [H] shifting from enteric CH4 inhibition.

The abundance and persistence of Caprinae populations.

Stable or growing populations may go extinct when their sizes cannot withstand large swings in temporal variation and stochastic forces. Hence, the minimum abundance threshold defining when populations can persist without human intervention forms a key conservation parameter. We identify this threshold for many populations of Caprinae, typically threatened species lacking demographic data. Doing so helps triage conservation and management actions for threatened or harvested populations. Methodologically, we used population projection matrices and simulations, with starting abundance, recruitment, and adult female survival predicting future abundance, growth rate (λ), and population trend. We incorporated mean demographic rates representative of Caprinae populations and corresponding variances from desert bighorn sheep (Ovis canadensis nelsoni), as a proxy for Caprinae sharing similar life histories. We found a population's minimum abundance resulting in ≤ 0.01 chance of quasi-extinction (QE; population ≤ 5 adult females) in 10 years and ≤ 0.10 QE in 30 years as 50 adult females, or 70 were translocation (removals) pursued. Discovering the threshold required 3 demographic parameters. We show, however, that monitoring populations' relationships to this threshold requires only abundance and recruitment data. This applied approach avoids the logistical and cost hurdles in measuring female survival, making assays of population persistence more practical.

History, insights, and future perspectives on studies into luteal function in cattle.

The corpus luteum (CL) forms following ovulation from the remnant of the Graafian follicle. This transient tissue produces critical hormones to maintain pregnancy, including the steroid progesterone. In cattle and other ruminants, the presence of an embryo determines if the lifespan of the CL will be prolonged to ensure successful implantation and gestation, or if the tissue will undergo destruction in the process known as luteolysis. Infertility and subfertility in dairy and beef cattle results in substantial economic loss to producers each year. In addition, this has the potential to exacerbate climate change because more animals are needed to produce high-quality protein to feed the growing world population. Successful pregnancies require coordinated regulation of uterine and ovarian function by the developing embryo. These processes are often collectively termed "maternal recognition of pregnancy." Research into the formation, function, and destruction of the bovine CL by the Northeast Multistate Project, one of the oldest continuously funded Hatch projects by the USDA, has produced a large body of evidence increasing our knowledge of the contribution of ovarian processes to fertility in ruminants. This review presents some of the seminal research into the regulation of the ruminant CL, as well as identifying mechanisms that remain to be completely validated in the bovine CL. This review also contains a broad discussion of the roles of prostaglandins, immune cells, as well as mechanisms contributing to steroidogenesis in the ruminant CL. A triadic model of luteolysis is discussed wherein the interactions among immune cells, endothelial cells, and luteal cells dictate the ability of the ruminant CL to respond to a luteolytic stimulus, along with other novel hypotheses for future research.

The corpus luteum (CL) forms on the ovary from the cellular remnants of the follicle following ovulation. The function of the CL is to produce progesterone that is required for successful pregnancy. In the absence of an embryo or sufficient embryonic signaling, the uterus will release a prostaglandin that kills the CL in a process called luteolysis. Therefore, the CL and the embryo share a symbiotic relationship, each requiring the other to be healthy and functional for survival. The Northeast Multistate Project, one of the oldest in the nation, has produced a large body of evidence that has enhanced our understanding of how the CL functions, its regulation, and the impact of ovarian activity on fertility of cattle. This review highlights some of the important advances made in the understanding of the ruminant CL.

Reticular contraction frequency and ruminal gas dome development in goats do not differ between grass and browse diets.

In investigations of differences between ruminant species feeding on browse or grass, it is often unclear whether observed differences are animal- or forage-specific. Ruminant species have been classified as 'moose-type', with little rumen content stratification, or 'cattle-type' with a distinct rumen contents stratification, including a gas layer. To which extent putative differences in forestomach motility are involved in these patterns is unknown. Using sonography, we investigated the frequency of reticular contractions and the stratification of rumen contents in goats fed exclusively on grass hay (n = 6) or dried browse (n = 5) directly after feeding, and after another 6 and 12 h with no access to feed. The frequency of reticular contractions decreased from immediately after feeding (1.8 ± 0.3 min-1 ) to 6 h afterwards (1.2 ± 0.2 min-1 ) and then remained constant, with no difference between diets. A gas dome became more visible over time, but neither its incidence nor its extent differed between diets. The results are in accord with classifying goats as 'cattle-type' in terms of their digestive physiology, and they add to a growing body of evidence that differences in digestive physiology between ruminant species are more due to species characteristics than different kinds of ingested forages.

Biochemical and hormonal parameters of goats kept in a controlled environment consuming water with different levels of salinity / [Parâmetros bioquímicos e hormonais de caprinos consumindo água com diferentes níveis de salinidade mantidos em ambiente controlado]

The objective of this work was to evaluate the biochemical and hormonal variables of Moxotó and Canindé goats submitted to two temperatures - 26.0±0.6 (thermoneutral) and 32.0±1.2°C (above thermal comfort zone) - and consuming water with three levels of salinity (1.0, 6.0 and 12.0 dSm-1). Thirty-six animals (18 of each breed) were used, with an average age of 5.0±0.6months and an average weight of 20.0±2.3kg, housed in metabolic cages inside a climate chamber. The animals were distributed in a completely randomized design with a 2 × 2 × 3 factorial scheme (2 breeds, 2 temperatures and 3 levels of salinity) and three replications. The glucose and urea had a significant effect (P>0.05) according to water salinity. Glucose, cholesterol, protein, albumin, globulin, aspartate aminotransferase and hormones (T4, T3 and cortisol) varied according to temperature (P<0.05). There was a significant effect of time on hormonal variables (P<0.05). Biochemical and hormonal variables changed according to temperature and day shift, so that metabolism was reduced in the animals under thermal stress and accelerated when animals were in the thermal comfort zone.(AU)

O objetivo do trabalho foi avaliar as variáveis bioquímicas e hormonais de caprinos das raças Moxotó e Canindé, submetidos a duas temperaturas (26,0±0,6ºC e 32,0±1,2ºC), termoneutra e acima da zona de conforto térmico, respectivamente), consumindo água com três níveis de salinidade (1,0, 6,0 e 12,0dSm-1), utilizando-se 36 animais (18 de cada raça), com idade média de 5,0±0,6 meses e peso médio de 20,0±2,3kg, alojados em gaiolas metabólicas no interior de uma câmara climática. Os animais foram distribuídos em um delineamento inteiramente ao acaso, com esquema fatorial de 2 x 2 x 3 (2 raças, 2 temperaturas e 3 níveis de salinidade) e três repetições. A glicose e a ureia apresentaram efeito significativo (P<0,05) em função da salinidade da água. Glicose, colesterol, proteína, albumina, globulina, AST e hormônios (T4, T3 e cortisol) variaram conforme as temperaturas (P<0,05). Observou-se efeito significativo do horário sobre as variáveis hormonais (P<0,05). As variáveis bioquímicas e hormonais sofrem alterações em função da temperatura e do turno do dia, de modo que o metabolismo é reduzido em animais sob estresse térmico e acelerado quando os animais encontram-se na zona de conforto térmico.(AU)

Weapons Evolve Faster Than Sperm in Bovids and Cervids.

In polyandrous species, males face reproductive competition both before and after mating. Sexual selection thus shapes the evolution of both pre- and postcopulatory traits, creating competing demands on resource allocation to different reproductive episodes. Traits subject to strong selection exhibit accelerated rates of phenotypic divergence, and examining evolutionary rates may inform us about the relative importance and potential fitness consequences of investing in traits under either pre- or postcopulatory sexual selection. Here, we used a comparative approach to assess evolutionary rates of key competitive traits in two artiodactyl families, bovids (family Bovidae) and cervids (family Cervidae), where male-male competition can occur before and after mating. We quantified and compared evolutionary rates of male weaponry (horns and antlers), body size/mass, testes mass, and sperm morphometrics. We found that weapons evolve faster than sperm dimensions. In contrast, testes and body mass evolve at similar rates. These results suggest strong, but differential, selection on both pre- and postcopulatory traits in bovids and cervids. Furthermore, we documented distinct evolutionary rates among different sperm components, with sperm head and midpiece evolving faster than the flagellum. Finally, we demonstrate that, despite considerable differences in weapon development between bovids and cervids, the overall evolutionary patterns between these families were broadly consistent.

The rumen microbiome: balancing food security and environmental impacts.

Ruminants produce edible products and contribute to food security. They house a complex rumen microbial community that enables the host to digest their plant feed through microbial-mediated fermentation. However, the rumen microbiome is also responsible for the production of one of the most potent greenhouse gases, methane, and contributes about 18% of its total anthropogenic emissions. Conventional methods to lower methane production by ruminants have proved successful, but to a limited and often temporary extent. An increased understanding of the host-microbiome interactions has led to the development of new mitigation strategies. In this Review we describe the composition, ecology and metabolism of the rumen microbiome, and the impact on host physiology and the environment. We also discuss the most pertinent methane mitigation strategies that emerged to balance food security and environmental impacts.

Physical characteristics of forestomach contents from two nondomestic small ruminants, the blackbuck (Antilope cervicapra) and the Arabian sand gazelle (Gazella subgutturosa marica).

Rumen content stratification and the degree of dissociation of particle and fluid retention in the reticulorumen differ between 'moose-type' and 'cattle-type' ruminant species. These differences are not strictly linked to diet, except for a seeming limitation of 'moose-type' ruminants to a browsing niche. Nevertheless, these differences can be plausibly linked to other observed differences in ruminants, such as the intraruminal papillation pattern, or the size of the omasum. However, many of the corresponding measures are still only available for a restricted number of species. Here, we investigated the dry matter (i.e., the inverse of the moisture) concentration in forestomach contents of 10 blackbuck (Antilope cervicapra) and 7 Arabian sand gazelle (Gazella subgutturosa marica), and quantified the rumen papillation pattern. The blackbucks had distinct rumen contents stratification, with more moisture in ventral than in dorsal contents (difference 3.6% units, P < 0.001), whereas this difference was much less pronounced in the sand gazelles (0.6% units, P = 0.227). While reticulum contents were particularly moist in both species, omasum contents were particularly dry in sand gazelles, but did not differ in moisture from rumen contents in the blackbuck. This species is an outlier among ruminants due to its extremely small omasum. The intraruminal papillation pattern did not differ between blackbucks and sand gazelles and showed a surface enlargement factor (SEF) in the dorsal rumen of 27-28% of the SEF in the Atrium ruminis. Compared to data on digesta retention in the same species, the findings are in line with the overall concept of a high fluid throughput causing a distinct stratification of rumen contents and intraruminal papillation, and necessitating a large omasum for fluid re-absorption. However, the data also show that individual species may not correspond to all the assumptions of the concept, suggesting taxon-specific differences between species. Reasons for these differences cannot be linked to a dietary grass-browse spectrum, but may lie in evolutionary contingency.

Nutritional Regulation of Mammary Gland Development and Milk Synthesis in Animal Models and Dairy Species.

In mammals, milk is essential for the growth, development, and health. Milk quantity and quality are dependent on mammary development, strongly influenced by nutrition. This review provides an overview of the data on nutritional regulations of mammary development and gene expression involved in milk component synthesis. Mammary development is described related to rodents, rabbits, and pigs, common models in mammary biology. Molecular mechanisms of the nutritional regulation of milk synthesis are reported in ruminants regarding the importance of ruminant milk in human health. The effects of dietary quantitative and qualitative alterations are described considering the dietary composition and in regard to the periods of nutritional susceptibly. During lactation, the effects of lipid supplementation and feed restriction or deprivation are discussed regarding gene expression involved in milk biosynthesis, in ruminants. Moreover, nutrigenomic studies underline the role of the mammary structure and the potential influence of microRNAs. Knowledge from three lactating and three dairy livestock species contribute to understanding the variety of phenotypes reported in this review and highlight (1) the importance of critical physiological stages, such as puberty gestation and early lactation and (2) the relative importance of the various nutrients besides the total energetic value and their interaction.

Ação inseticida in vitro do óleo essencial de Lippia gracilisSchauer sobre Damalinia Bovicola ovis (Schrank, 1781) / In vitro action of Lippia gracilis Schauer essential oil on Damalinia Bovicola ovis (Schrank, 1781)

O objetivo deste trabalho é avaliar a eficácia inseticida in vitro do óleo essencial de Lippia gracilis sobre Bovicolaovis. Os espécimes (n = 900) de B.ovis foram coletados de ovinos naturalmente infestados, distribuídos aleatoriamente em grupos, e submetidos aos diferentes tratamentos: (G1) 1.000 a 15,6 mg/ml óleo essencial de Lippia gracilis; (G2) Tween 80 a 3% (controle negativo), e: (G3) Amitraz 1,25 g/mL (controle positivo). Realizou-se 4 réplicas (25 piolhos por réplica) para cada tratamento. A viabilidade dos piolhos foi avaliada nos tempos de 1, 3, 6, 24, 48 e 72 h. Os dados foram expressos em eficácia média ± desvio padrão (SPSS versão 23.0) e diferenças estatísticas dos grupos experimentais foram obtidas por Kruskal-Wallis e Friedman. Para obtenção da CI50e CI90 foi realizada Regressão de Probit, com nível de significância de p< 0,05. O óleo essencial de L. gracilis nas concentrações de 100 a 62,5 mg/mL apresentaram eficácia de 100%, 1 h pós-exposição. Os valores de CI50 e CI90 foram 18,1 mg/mL e 44,9 mg/mL, respectivamente. Dessa forma, concluímos que o óleo essencial de L. gracilis apresentou eficácia sobre B.ovis in vitro.

The objective of this work is to evaluate the in vitro insecticidal efficacy of the essential oil of Lippia gracilis against Bovicolaovis. The specimens (n = 900) of B.ovis were collected from naturally infested sheep, randomly distributed in groups, and subjected to different treatments: (G1) 1,000 to 15.6 mg/ml essential oil of Lippia gracilis; (G2) 3% Tween 80 (negative control), and: (G3) Amitraz 1.25 g/mL (positive control). 4 replicates (25 lice per replica) were performed for each treatment. Louse viability was assessed at 1, 3, 6, 24, 48 and 72 h. The data were expressed as mean efficacy ± standard deviation (SPSS version 23.0) and statistical differences in the experimental groups were obtained by Kruskal-Wallis and Friedman. Probit regression was performed to obtain the IC50 and CI90, with a significance level of p <0.05. The essential oil of L. gracilis at concentrations of 100 to 62.5 mg/mL showed 100% efficacy, 1 h post-exposure. The IC50 and CI90 values were 18.1 mg/mL and 44.9 mg/mL, respectively. Thus, we conclude that L. gracilis essential oil is effective on B. ovis.

Cultivating oyster mushrooms on red grape pomace waste enhances potential nutritional value of the spent substrate for ruminants.

The use of red grape pomace (GP; Vitis vinifera L. var. Shiraz) as a source of beneficial bioactive compounds in ruminant diets is limited by high levels of indigestible compounds in the grape skin matrix. This problem demands innovative, inexpensive, and easy-to-use strategies that improve the digestibility of GP. The bioconversion of GP using edible oyster mushrooms (Pleurotus ostreatus) is one such strategy that has not been previously explored. Therefore, this study evaluated the effect of cultivating oyster mushrooms on GP on chemical composition and in vitro ruminal fermentation parameters of the spent mushroom substrate. The GP was inoculated with oyster mushroom spawns at 0, 200, 300, 400, or 500 g/kg, and incubated for 4 weeks. Organic matter, acid detergent lignin, sodium, manganese, cobalt, and copper linearly declined (P < 0.05) as spawn rates increased. A quadratic trend was observed for crude protein, neutral detergent fibre, acid detergent fibre, magnesium, phosphorus, and calcium content in response to increasing spawn rates. Higher spawning rates (20-50%) had a positive effect (P < 0.05) on gas production from the immediately fermentable fraction (a), rate of gas production from the slowly fermentable fraction (c) and effective gas production. However, gas production from the slowly fermentable fraction (b) and potential gas production linearly declined in response to increasing spawning rates. There was a linear increase (P < 0.05) in the immediately degradable fraction (a), while quadratic effects were observed for partition factors, effective degradability, and in vitro organic matter degradability at 48 h in response to spawning rates. It can be concluded that inoculating GP with oyster mushroom spawn reduced fibre content while increasing crude protein content and in vitro ruminal fermentation efficiency of red grape pomace. Based on the quadratic responses of partition factors at 48 hours post-inoculation, the optimum spawning rate for maximum ruminal fermentation efficiency of GP was determined to be 300 g/kg.

Impact of selected environmental factors on microbiome of the digestive tract of ruminants.

Ruminants are an important part of world animal production. The main factors affecting their production rates are age, diet, physiological condition and welfare. Disorders related to low level of welfare can significantly affect the microbiological composition of the digestive system, which is essential to maintain high production rates. The microbiology of the ruminant gastrointestinal tract may be significantly affected by inappropriate keeping system (especially in juveniles), psychological stress (e.g. transport), or heat stress. This results in an increased risk of metabolic diseases, reduced fertility and systemic diseases. Therefore, the paper focuses on selected disorders i.e., aforementioned inappropriate maintenance system, psychological stress, heat stress and their effects on the microbiome of the digestive system.

Methods to quantify heat stress in ruminants: Current status and future prospects.

The physiology of hyperthermia or heat stress in mammals is complex. It is a totally systemic condition that in varying degrees involves all organs, tissues and body fluid compartments. The nature and magnitude of the response is influenced by animal specific characteristics (e.g. age, diet, body condition, gender, reproductive stage), environment and animal management. Given the multifaceted nature of heat stress, and the varied ruminant production systems based in varied geoclimatic zones, it has been difficult to find appropriate measures of heat stress for production ruminants. This has become an urgent challenge as production systems intensify globally in a warming climate. Bioclimatic indices such as the Temperature-Humidity Index (THI) have evolved to incorporate some measure of animal physiology. However, these indices do not have strong relationships with core temperature trajectories and altered respiratory dynamics of animals with excessive heat load. In recent decades, the careful physiology studies of the 1950-80s, have given way to numerous studies trialling a plethora of new technologies and computational approached to measure heat stress. Infrared thermography of body surface temperatures, automated measures of respiration rate and radiotelemetry of internal body temperatures are the most intensively researched. The common goal has been to find the 'holy grail' decision-making threshold or timepoint as to the animal's wellbeing. Are we making any progress?

Rumen metaproteomics: Closer to linking rumen microbial function to animal productivity traits.

The rumen microbiome constitutes a dense and complex mixture of anaerobic bacteria, archaea, protozoa, virus and fungi. Collectively, rumen microbial populations interact closely in order to degrade and ferment complex plant material into nutrients for host metabolism, a process which also produces other by-products, such as methane gas. Our understanding of the rumen microbiome and its functions are of both scientific and industrial interest, as the metabolic functions are connected to animal health and nutrition, but at the same time contribute significantly to global greenhouse gas emissions. While many of the major microbial members of the rumen microbiome are acknowledged, advances in modern culture-independent meta-omic techniques, such as metaproteomics, enable deep exploration into active microbial populations involved in essential rumen metabolic functions. Meaningful and accurate metaproteomic analyses are highly dependent on representative samples, precise protein extraction and fractionation, as well as a comprehensive and high-quality protein sequence database that enables precise protein identification and quantification. This review focuses on the application of rumen metaproteomics, and its potential towards understanding the complex rumen microbiome and its metabolic functions. We present and discuss current methods in sample handling, protein extraction and data analysis for rumen metaproteomics, and finally emphasize the potential of (meta)genome-integrated metaproteomics for accurate reconstruction of active microbial populations in the rumen.

Multi-scale habitat assessment of pronghorn migration routes.

We studied the habitat selection of pronghorn (Antilocapra americana) during seasonal migration; an important period in an animal's annual cycle associated with broad-scale movements. We further decompose our understanding of migration habitat itself as the product of both broad- and fine-scale behavioral decisions and take a multi-scale approach to assess pronghorn spring and fall migration across the transboundary Northern Sagebrush Steppe region. We used a hierarchical habitat selection framework to assess a suite of natural and anthropogenic features that have been shown to influence selection patterns of pronghorn at both broad (migratory neighborhood) and fine (migratory pathway) scales. We then combined single-scale predictions into a scale-integrated step selection function (ISSF) map to assess its effectiveness in predicting migration route habitat. During spring, pronghorn selected for native grasslands, areas of high forage productivity (NDVI), and avoided human activity (i.e., roads and oil and natural gas wells). During fall, pronghorn selected for native grasslands, larger streams and rivers, and avoided roads. We detected avoidance of paved roads, unpaved roads, and wells at broad spatial scales, but no response to these features at fine scales. In other words, migratory pronghorn responded more strongly to anthropogenic features when selecting a broad neighborhood through which to migrate than when selecting individual steps along their migratory pathway. Our results demonstrate that scales of migratory route selection are hierarchically nested within each other from broader (second-order) to finer scales (third-order). In addition, we found other variables during particular migratory periods (i.e., native grasslands in spring) were selected for across scales indicating their importance for pronghorn. The mapping of ungulate migration habitat is a topic of high conservation relevance. In some applications, corridors are mapped according to telemetry location data from a sample of animals, with the assumption that the sample adequately represents habitat for the entire population. Our use of multi-scale modelling to predict resource selection during migration shows promise and may offer another relevant alternative for use in future conservation planning and land management decisions where telemetry-based sampling is unavailable or incomplete.