Biostimulating effect of l-tryptophan on the yield and chemical and microbiological quality of perennial ryegrass (Lolium perenne) herbage and silage for ruminant.

BACKGROUND: This study aimed to evaluate the effect of l-tryptophan (l-TRP) used in the cultivation of Lolium perenne on the yield, and chemical and microbiological quality of its herbage and silage. l-Tryptophan was applied in doses of 5, 0.5, 0.05 kg ha-1 . The experiment was conducted with a control group (C) and a comparative control group (C+) with higher nitrogen fertilization. RESULTS: The dose of 5 kg ha-1 had a significant effect on herbage yield, which increased by 15% compared to group C and approximated the value achieved in group C+. The treatment with l-TRP caused a significant increase in water-soluble carbohydrate (WSC) content only in Tr5 (165 g kg-1 DM), which was reflected in a more beneficial course of fermentation, lower pH (4.59), and a higher sum of fermentation acids, including lactic acid (94.7 g kg-1 DM). Ryegrass treatment with a high l-TRP dose effectively reduced the loads of Clostridium spp. and fungi, and increased the count of Bacillus spp. The l-TRP significantly reduced N-NH3 content in Tr05 (98.6 g kg-1 TN) compared with C+ (123 g kg-1 TN) and butyric acid content in Tr05 (from 1.35 g kg-1 DM in the C to 0.38 g kg-1 DM). CONCLUSION: The most effective dose turned out to be a dose of 5 kg ha-1 , which allowed a higher yield and a better fermentation course to be achieved. This work presents the feasibility of using l-TRP to optimize nutrient consumption by Lolium perenne and ultimately to affect the quality of its silage as a feedstuff. © 2020 Society of Chemical Industry.

Seasonal bone growth and physiology in endotherms shed light on dinosaur physiology.

Cyclical growth leaves marks in bone tissue that are in the forefront of discussions about physiologies of extinct vertebrates. Ectotherms show pronounced annual cycles of growth arrest that correlate with a decrease in body temperature and metabolic rate; endotherms are assumed to grow continuously until they attain maturity because of their constant high body temperature and sustained metabolic rate. This apparent dichotomy has driven the argument that zonal bone denotes ectotherm-like physiologies, thus fuelling the controversy on dinosaur thermophysiology and the evolution of endothermy in birds and mammal-like reptiles. Here we show, from a comprehensive global study of wild ruminants from tropical to polar environments, that cyclical growth is a universal trait of homoeothermic endotherms. Growth is arrested during the unfavourable season concurrently with decreases in body temperature, metabolic rate and bone-growth-mediating plasma insulin-like growth factor-1 levels, forming part of a plesiomorphic thermometabolic strategy for energy conservation. Conversely, bouts of intense tissue growth coincide with peak metabolic rates and correlated hormonal changes at the beginning of the favourable season, indicating an increased efficiency in acquiring and using seasonal resources. Our study supplies the strongest evidence so far that homeothermic endotherms arrest growth seasonally, which precludes the use of lines of arrested growth as an argument in support of ectothermy. However, high growth rates are a distinctive trait of mammals, suggesting the capacity for endogenous heat generation. The ruminant annual cycle provides an extant model on which to base inferences regarding the thermophysiology of dinosaurs and other extinct taxa.

Weight gain by gut microbiota manipulation in productive animals.

Antibiotics, prebiotics and probiotics are widely used as growth promoters in agriculture. In the 1940s, use of Streptomyces aureofaciens probiotics resulted in weight gain in animals, which led to the discovery of chlortetracycline. Tetracyclines, macrolides, avoparcin and penicillins have been commonly used in livestock agriculture to promote growth through increased food intake, weight gain, and improved herd health. Prebiotic supplements including oligosaccharides, fructooligosaccharides, and galactosyl-lactose improve the growth performance of animals. Probiotics used in animal feed are mainly bacterial strains of Gram-positive bacteria and have been effectively used for weight gain in chickens, pigs, ruminants and in aquaculture. Antibiotics, prebiotics and probiotics all modify the gut microbiota and the effect of a probiotic species on the digestive flora is probably determined by bacteriocin production. Regulations governing the introduction of novel probiotics and prebiotics vary by geographical region and bias is very common in industry-funded studies. Probiotic and prebiotic foods have been consumed for centuries, either as natural components of food, or as fermented foods and it is possible to cause the same weight gain effects in humans as in animals. This review presents the use of growth promoters in food-producing animals to influence food intake and weight gain.

Differences between two strains of Ceriporiopsis subvermispora on improving the nutritive value of wheat straw for ruminants.

AIM: This study evaluated differences between two strains of Ceriporiopsis subvermispora on improving the nutritive value and in vitro degradability of wheat straw. METHODS AND RESULTS: Wheat straw was treated with the fungi for 7 weeks. Weekly samples were analysed for ergosterol content, in vitro gas production (IVGP), chemical composition and lignin-degrading enzyme activity. Ergosterol data showed CS1 to have a faster initial growth than CS2 and reaching a stationary phase after 3 weeks. The IVGP of CS1-treated wheat straw exceeded the control earlier than CS2 (4 vs 5 weeks). CS1 showed a significantly higher (P < 0·001) selectivity in lignin degradation compared to CS2. Both strains showed peak activity of laccase and manganese peroxidase (MnP) at week 1. CS1 showed a significantly higher (P < 0·001) laccase activity, but lower (P = 0·008) MnP activity compared to CS2. CONCLUSION: Both CS strains improved the nutritive value of wheat straw. Variation between strains was clearly demonstrated by their growth pattern and enzyme activities. SIGNIFICANCE AND IMPACT OF THE STUDY: The differences among the two strains provide an opportunity for future selection and breeding programs in improving the extent and selectivity of lignin degradation in agricultural biomass.

Conservation efforts of captive golden takin (Budorcas taxicolor bedfordi) are potentially compromised by the elevated chemical elements exposure.

Chemical elements exposure of endangered golden takins (Budorcas taxicolor bedfordi) living in the Qinling Mountains and in a captive breeding center was assessed by analyzing fecal samples. Concentrations of As, Co, Cr, Cu, Ni and Se were significantly higher in the feces of captive golden takins than the wild. There was no significant difference in the fecal concentrations of Cd, Mn, Hg, Pb or Zn for wild and captive animals. The element concentration of fecal samples collected from captive animals varied seasonally, with concentrations being lowest in spring and highest in winter and/or autumn. The food provided to captive animals varied both in the composition and the concentration of element present. Consumptions of feedstuff and additional foods such as D. sanguinalis and A. mangostanus for the captive golden takins were identified as the possible sources of chemical element exposure. The estimations of dietary intake of most elements by captive takins were below the oral reference dose, except for As and Pb, indicating that As and Pb were the key components which contributed to the potential non-carcinogenic risk for captive golden takins. In conclusion, captive golden takins were exposed to higher concentrations of chemical elements compared with the wild, which were likely due to their dietary difference. Conservation efforts of captive golden takin are potentially compromised by the elevated chemical element exposure and effort should focus on providing uncontaminated food for captive animals.

Impacts of fat from ruminants' meat on cardiovascular health and possible strategies to alter its lipid composition.

In the last few decades there has been increased consumer interest in the fatty acid (FA) composition of ruminant meat due to its content of saturated FAs, which have been implicated in diseases associated with modern life. However, recent studies have questioned the recommendations to reduce intake of fat, saturated FAs and cholesterol as a means of reducing the risk of cardiovascular disease. Interestingly, ruminant meat has some bioactive lipids such as C18:1t11 and C18:2 c9, t11 which have been reported to have positive effects on human health. In order to improve muscle fat composition from a human health standpoint, oilseeds, plant oils and marine oils can be used in ruminant diets. On the other hand, molecular mechanisms play an important role in the alteration of the FA composition of muscle fat. Genetics offer a wide range of possibilities for improvement of muscle fat composition by identifying different loci underlying the expression of quantitative traits. While significant progress has been made in characterizing the influence of diet on the FA composition of ruminant meat, the use of genetic tools can favor genotypes that could maximize their genetic potential through the diet. © 2016 Society of Chemical Industry.

Conserving wildlife amongst the cotton fields. A third of a century of experience at the Nazinga Game Ranch, Burkina Faso.

Established in the early 1970 as a participatory wildlife production area, the Nazinga Game Ranch turned into an island of conservation surrounded by cultivation. We asked ourselves how long-term ungulate trends are affected in a context of continuous human pressure. To find out, we compiled and analysed the data of yearly line-transect counts of mammals carried out since 1985. Results showed that large species such as the elephant (Loxodonta africana) and large antelopes increased or showed stable populations. In contrast, medium and small ungulates showed continuously decreasing trends. During the same period, rainfall, water availability from artificial water points and the crop encroaching outside Nazinga Game Ranch increased. After an initial significant reduction, illegal human signs increased. However, we showed that human signs were positively correlated with the abundance of large ungulates but negatively correlated with the abundance of medium and small ones. In conclusion, this study showed that some isolated mammal populations could be restored and maintained in the long term, in spite of being surrounded by highly cultivated areas.

The role of maternal behavior and offspring development in the survival of mountain goat kids.

Studies on juvenile survival have mainly focused on the effects of environmental conditions and maternal traits. However, growing evidence indicates that the ability of parents to care for their young and the offspring developmental behaviors could be key determinants of their survival. We examined the relative influence of (1) environmental conditions, (2) offspring traits, (3) maternal traits, (4) maternal care behaviors, and (5) offspring developmental behaviors on kid survival to weaning and to 1 year old in mountain goats (Oreamnos americanus). Offspring development and maternal care directly affected offspring survival, and this more importantly than did environmental conditions and maternal traits. Frequency of play strongly increased survival before weaning. Greater maternal care increased offspring survival during winter, directly and indirectly through kid mass. Kid mass was also a major determinant of both summer and winter survival. Environmental conditions mainly influenced summer survival while maternal characteristics indirectly affected winter survival through an effect on kid mass. Behavioral adaptations of maternal care and offspring development to local selective pressures can lead to local adaptations and have greater implications in population dynamic studies than previously believed.

Condensed tannin accumulation and nitrogen fixation potential of Onobrychis viciifolia Scop. grown in a Mediterranean environment.

BACKGROUND: Sainfoin (Onobrychis viciifolia Scop.) is a forage legume found in temperate areas but is less widespread in Mediterranean environments. Compared with other perennial legumes, it has the advantage of containing condensed tannins (CT) that can be important for their implications on ruminant nutrition and health. Data on nitrogen (N) fixation by sainfoin in the literature originate from very different environments and only a few field data are available, so it is important to improve knowledge on the N fixation potential of this species, particularly under a Mediterranean climate. Here the accumulation pattern of polyphenolic compounds (total, non-tannic polyphenols and CT) and the N fixation potential of sainfoin were studied in order to contribute to its valorisation for sustainable farming management in Mediterranean environments. RESULTS: CT concentrations were always in the range considered beneficial for animals, not exceeding 50 g delphinidin equivalent kg⁻¹ dry matter (DM). The regression of aerial fixed N on aerial DM showed a relationship of 22 kg fixed N t⁻¹ aerial DM in a Mediterranean environment. CONCLUSION: A wider exploitation of sainfoin is suggested for production under rain-fed conditions, thus enlarging the limited set of available perennial legumes suitable for Mediterranean environments.

The role of grasslands in food security and climate change.

BACKGROUND: Grasslands are a major part of the global ecosystem, covering 37 % of the earth's terrestrial area. For a variety of reasons, mostly related to overgrazing and the resulting problems of soil erosion and weed encroachment, many of the world's natural grasslands are in poor condition and showing signs of degradation. This review examines their contribution to global food supply and to combating climate change. SCOPE: Grasslands make a significant contribution to food security through providing part of the feed requirements of ruminants used for meat and milk production. Globally, this is more important in food energy terms than pig meat and poultry meat. Grasslands are considered to have the potential to play a key role in greenhouse gas mitigation, particularly in terms of global carbon storage and further carbon sequestration. It is estimated that grazing land management and pasture improvement (e.g. through managing grazing intensity, improved productivity, etc) have a global technical mitigation potential of almost 1·5 Gt CO(2) equivalent in 2030, with additional mitigation possible from restoration of degraded lands. Milk and meat production from grassland systems in temperate regions has similar emissions of carbon dioxide per kilogram of product as mixed farming systems in temperate regions, and, if carbon sinks in grasslands are taken into account, grassland-based production systems can be as efficient as high-input systems from a greenhouse gas perspective. CONCLUSIONS: Grasslands are important for global food supply, contributing to ruminant milk and meat production. Extra food will need to come from the world's existing agricultural land base (including grasslands) as the total area of agricultural land has remained static since 1991. Ruminants are efficient converters of grass into humanly edible energy and protein and grassland-based food production can produce food with a comparable carbon footprint as mixed systems. Grasslands are a very important store of carbon, and they are continuing to sequester carbon with considerable potential to increase this further. Grassland adaptation to climate change will be variable, with possible increases or decreases in productivity and increases or decreases in soil carbon stores.

A review of poisonous plants that cause reproductive failure and malformations in the ruminants of Brazil.

The objective of this review is to provide a report on toxic plants causing reproductive problems in ruminants in Brazil. Aspidosperma pyrifolium causes abortion or stillbirth in goats, as well as most likely in sheep and cattle, in the semiarid regions of Northeastern Brazil. Intoxications by Ateleia glazioveana, Tetrapterys acutifolia and T. multiglandulosa result in abortion and neonatal mortality in cattle and sheep, and the same signs have been experimentally observed in goats. These three plants can also cause cardiac fibrosis and a nervous disease with spongiosis of the central nervous system. Other plants known to cause abortion include Enterolobium contortisiliquum, E. gummiferum, Stryphnodendron coriaceum, S. obovatum and S. fissuratum. These plants can also cause digestive signs and photosensitization. Abortions have been reported in animals intoxicated by nitrates and nitrites as well. Infertility, abortions and the birth of weak offspring have been reported in animals intoxicated by plants containing swainsonine, including Ipomoea spp., Turbina cordata and Sida carpinifolia. Trifolium subterraneum causes estrogenism in cattle. Mimosa tenuiflora and, most likely, M. ophthalmocentra cause malformations and embryonic mortality in goats, sheep and cattle in the semiarid regions of Northeastern Brazil.

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.

Inbreeding depression in pronghorn (Antilocapra americana) fawns.

Although inbreeding depression affects survival, fitness and population viability, the extent of inbreeding depression in wild populations remains unclear. We examined inbreeding depression in the small, isolated National Bison Range (NBR), MT, pronghorn (Antilocapra americana) population following a bottleneck. We have studied the National Bison Range pronghorn extensively since 1981, and we have detailed birth, survival and mate choice data. We genotyped all animals in the population between 1999 and 2010 at 19 microsatellite loci, assigned paternities to all fawns based on genotype and constructed a genetic-based pedigree to calculate inbreeding coefficients (f). We found an increase in the frequency of inbreeding following the bottleneck. We detected evidence of inbreeding depression on fawn survival to weaning, birth mass, foot length and condition. We estimated the number of diploid lethal equivalents on survival to weaning as 24.17-28.72. Standardized heterozygosity (H) had a relatively small influence on survival, mass, length and condition compared with f, and H was not correlated with f. We conclude that for pronghorn, H was not a good predictor of pedigree-estimates of f.

The shrinking ark: patterns of large mammal extinctions in India.

Mammal extinctions are widespread globally, with South Asian species being most threatened. We examine local extinctions of 25 mammals in India. We use historical records to obtain a set of locations at which each species was known to have been present at some time in the last 200 years. We then use occupancy estimation models to draw inferences about current presence at these same locations based on field observations of local experts. We examine predictions about the influence of key factors such as protected areas, forest cover, elevation, human population density and cultural tolerance on species extinction. For all 25 species, estimated local extinction probabilities (referenced to a 100 year time frame) range between 0.14 and 0.96. Time elapsed since the historical occurrence record was an important determinant of extinction probability for 14 species. Protected areas are positively associated with lower extinction of 18 species, although many species occur outside them. We find evidence that higher proportion of forest cover is associated with lower extinction probabilities for seven species. However, for species that prefer open habitats (which have experienced intensive land-use change), forest cover alone appears insufficient to ensure persistence (the complement of extinction). We find that higher altitude is positively associated with lower extinction for eight species. Human population density is positively associated with extinction of 13 species. We find that 'culturally tolerated' species do exhibit higher persistence. Overall, large-bodied, rare and habitat specialist mammals tend to have higher extinction probabilities.

From fetus to adult--an allometric analysis of the giraffe vertebral column.

As mammalian cervical vertebral count is almost always limited to seven, the vertebral column of the giraffe (Giraffa camelopardalis) provides an interesting study on scaling and adaptation to shape in light of these constraints. We have defined and described the growth rates of the lengths, widths, and heights of the vertebrae from fetal through neonatal life to maturity. We found that the disproportionate elongation of the cervical vertebrae is not a fetal process but occurs after birth, and that each cervical (C2-C7) vertebrae elongates at the same rate. C7 is able to specialize toward elongation as its function has been shifted to T1. We concluded that T1 is a transitional vertebra whose scaling exponent and length is between that of the cervical and thoracic series. Despite its transitional nature, T1 is still regarded as thoracic, as it possesses an articulating rib that attaches to the sternum. The other dimensions taken (width, height, and spinous process length) show that giraffe vertebral morphology exhibit adaptations to biomechanical strain, and we have underlined the importance of the thoracic spinous processes in supporting the head and neck.

Effect of small-scale heterogeneity of prey and hunter distributions on the sustainability of bushmeat hunting.

Bushmeat is the main source of protein and the most important source of income for rural people in the Congo Basin, but intensive hunting of bushmeat species is also a major concern for conservationists. Although spatial heterogeneity in hunting effort and in prey populations at the landscape level plays a key role in the sustainability of hunted populations, the role of small-scale heterogeneity within a village hunting territory in the sustainability of hunting has remained understudied. We built a spatially explicit multiagent model to capture the dynamics of a system in which hunters and preys interact within a village hunting territory. We examined the case of hunting of bay duikers (Cephalophus dorsalis) in the village of Ntsiété, northeastern Gabon. The impact of hunting on prey populations depended on the spatial heterogeneity of hunting and prey distribution at small scales within a hunting area. Within a village territory, the existence of areas hunted throughout the year, areas hunted only during certain seasons, and unhunted areas contributed to the sustainability of the system. Prey abundance and offtake per hunter were particularly sensitive to the frequency and length of hunting sessions and to the number of hunters sharing an area. Some biological parameters of the prey species, such as dispersal rate and territory size, determined their spatial distribution in a hunting area, which in turn influenced the sustainability of hunting. Detailed knowledge of species ecology and behavior, and of hunting practices are crucial to understanding the distribution of potential sinks and sources in space and time. Given the recognized failure of simple biological models to assess maximum sustainable yields, multiagent models provide an innovative path toward new approaches for the assessment of hunting sustainability, provided further research is conducted to increase knowledge of prey species' and hunter behavior.

The use of essential oils as a growth promoter for small ruminants: a systematic review and meta-analysis.

Background: Due to their antimicrobial properties and safety, essential oils are currently proposed as a sustainable option for antibiotic alternatives in the livestock sector. This current systematic review and meta-analysis investigated the effects of dietary essential oil supplements on dry matter intake (DMI), average daily gain (ADG), and feed conversion ratio (FCR) of small ruminants. Methods: A total of 12 studies (338 small ruminants) were included in this meta-analysis. The overall effect size was quantified using Hedges' g with 95% confidence interval (CI) using a fixed-effect model. Publication bias was inspected using Begg's and Egger's tests, followed by trim and fill method to detect the number of potential missing studies. Results: Insignificant heterogeneity among studies was detected both on DMI ( P of Q = 0.810; I-square = 0.00%), ADG ( P of Q = 0.286; I-square = 17.61%), and FCR ( P of Q = 0.650; I-square = 0.00%). The overall effect size showed that essential oils supplementation had no significant impact on DMI (Hedges' g = -0.12; 95% CI = -0.50 to 0.26; P = 0.429) and FCR (Hedges' g = -0.17; 95% CI = -0.55 to 0.22; P = 0.284), but had a significant positive impact on ADG (Hedges' g = 0.44; 95% CI = 0.12 to 0.76; P = 0.002). The result of publication bias analysis showed that DMI, ADG, and FCR did not present any significant biases ( P > 0.10), and no potential missing studies detected. Conclusions: Dietary essential oil could improve ADG of small ruminants, without any alteration on DMI and FCR. Further research in this topic is still required to provide stronger evidence of the potency of essential oil as a growth promoter for small ruminants.

Identifying priority conservation areas in a Saharan environment by highlighting the endangered Cuvier's Gazelle as a flagship species.

Monitoring populations and designing effective conservation actions for endangered species present significant challenges. An accurate understanding of current distribution, ecological traits and habitat requirements is imperative in formulating conservation strategies. Recent surveys on the southernmost Cuvier's Gazelle (Gazella cuvieri) population, an ungulate endemic to North Africa, showcase its importance in terms of numbers and genetic diversity. This population inhabits a remote region in the extreme north-western portion of the Sahara Desert and has not been well studied. Here, we examine the potential distribution of Cuvier's Gazelle and the environmental factors limiting the species in a Saharan environment, by combining broad-scale field survey data and species distribution models. Our objective was to identify high priority conservation areas in the southernmost known portion of the species' distribution by modelling habitat selection at the landscape scale using a predictive distribution map. Our results show that the distribution of Cuvier's Gazelle is strongly related to mountainous areas with heterogeneous terrain and remoteness from large human settlements over other ecological factors that had less impact on the species' presence and distribution. We also provide a quantitative estimate of the potential distribution range of Cuvier's Gazelle in southern Morocco, identifying two well-demarcated key areas. The two core areas currently contain enough rugged terrain isolated from human encroachment to support the endangered species in this harsh desert environment. We encourage the implementation of conservation planning for Cuvier's Gazelle as an "umbrella species", which will confer effective protection to higher-quality habitat zones and co-occurring species, leading to sustainable and ecologically responsible development in the region.

Formation, structure, and function of extra-skeletal bones in mammals.

This review describes the formation, structure, and function of bony compartments in antlers, horns, ossicones, osteoderm and the os penis/os clitoris (collectively referred to herein as AHOOO structures) in extant mammals. AHOOOs are extra-skeletal bones that originate from subcutaneous (dermal) tissues in a wide variety of mammals, and this review elaborates on the co-development of the bone and skin in these structures. During foetal stages, primordial cells for the bony compartments arise in subcutaneous tissues. The epithelial-mesenchymal transition is assumed to play a key role in the differentiation of bone, cartilage, skin and other tissues in AHOOO structures. AHOOO ossification takes place after skeletal bone formation, and may depend on sexual maturity. Skin keratinization occurs in tandem with ossification and may be under the control of androgens. Both endochondral and intramembranous ossification participate in bony compartment formation. There is variation in gradients of density in different AHOOO structures. These gradients, which vary according to function and species, primarily reduce mechanical stress. Anchorage of AHOOOs to their surrounding tissues fortifies these structures and is accomplished by bone-bone fusion and Sharpey fibres. The presence of the integument is essential for the protection and function of the bony compartments. Three major functions can be attributed to AHOOOs: mechanical, visual, and thermoregulatory. This review provides the first extensive comparative description of the skeletal and integumentary systems of AHOOOs in a variety of mammals.

Dietary protein and calcium modulate parathyroid vitamin D receptor expression in young ruminants.

For economic reasons and in order to minimize nitrogen excretion and thus pollution, the crude protein content in the diet of livestock animals should be as low as possible without negatively affecting the animals´ health and performance. As ruminants can efficiently use dietary protein because of the ruminohepatic circulation of urea, they are considered to cope more easily with such a feeding regime than monogastric animals. However, despite unaltered daily weight gain, massive changes in mineral homeostasis and vitamin D metabolism were observed with dietary protein reduction (N-) in young, growing goats. Serum concentrations of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) were decreased with a low N intake, even if calcium (Ca) was also restricted (Ca-). Interestingly, concentrations of cyclic adenosine monophosphate (cAMP) measured as an indirect assessment for the parathyroid hormone (PTH) activity were not affected by low protein. Therefore, it was hypothesized that the sensitivity of the parathyroid gland is modulated during these dietary interventions. Four groups of male German colored goats received a control (N+/Ca+), a reduced protein (N-/Ca+), a reduced Ca (N+/Ca-) or a reduced protein and Ca (N-/Ca-) diet. After six weeks we determined the expression of PTH, PTH receptor, Ca sensing receptor (CASR), vitamin D receptor (VDR), retinoid X receptor (RXRα), Klotho, fibroblast growth factor receptor 1c-splicing form, and the sodium-dependent Pi transporter (PiT1) in the parathyroid glands. Concentrations of cAMP were not affected, while those of Ca and 1,25-(OH)2D3were diminished and that of 25-hydroxyvitamin D3 was increased with N- feeding. The expression patterns of the described target genes were not altered. In contrast, animals fed the Ca- rations showed enhanced serum 1,25-(OH)2D3 and cAMP levels with no changes in blood Ca concentrations demonstrating an efficient adaptation. The mRNA expression of expression of VDR and CASR in the parathyroid gland was significantly diminished and RXRα, PTHR and PiT1 expression was elevated. Instead of the assumed desensitization of the parathyroid gland with N-, our results indicate elevated responsiveness to decreased blood Ca with feeding Ca-.