Adipose tissue metabolism and its role in adaptations to undernutrition in ruminants

Effects of Supplemental Calcium Propionate and Concentrate Level: Growth Performance, Body Fat Reserves, and Health of High-Risk Beef Calves

The aim of this study was to examine the impact of daily calcium propionate (CaPr) supplementation (0 or 20 g/calf) on growth performance, dietary energetics, body fat reserves, serum metabolites, and hematological responses in high-risk beef calves fed diets with varying (50, 60, or 70%) concentrate (CON) levels. In addition, a cost/income analysis of CaPr supplementation was carried out. Forty-eight crossbred bull calves (152.8 ± 1.56 kg body weight and 5.5 months of age) were involved in a fully randomized experimental design employing a 2 × 3 factorial arrangement of treatments. Calves were allocated (n = 8 per treatment) to individual pens (3.14 × 5.25 m) and were subjected to one of the following treatments during 42 d: No CaPr supplementation in diets containing 50, 60, or 70% CON (NoCaPr + 50, NoCaPr + 60, NoCaPr + 70, respectively) or daily CaPr supplementation dosed at 20 g/calf in diets containing 50, 60, or 70% CON (20CaPr + 50, 20CaPr + 60, 20CaPr + 70, respectively). Non-supplemented calves exhibited decreased dry matter intake (DMI) with increasing CON levels in their diets, while CaPr-supplemented calves displayed the opposite effect (interaction, p = 0.04). In calves fed a lower-CON diet (50%), those supplemented with CaPr showed greater average daily gain (ADG, 20.2%, p = 0.05) and lower DMI (2.2%, p = 0.03), resulting in improved ADG/DMI ratio, dietary energy, and energy retention (24.6, 14.4, and 18%, p < 0.05). These effects diminished when calves received diets with 60 or 70% CON but led to a 14.2% increase in rump fat thickness (p = 0.04). Only in non-supplemented CaPr calves, increasing the level of CON from 50 to 70% in the diet increased ADG (21.2%), decreased DMI (2.2%), and improved the ADG/DMI ratio (22.7%), with no impact on dietary net energy utilization. Non-supplemented calves exhibited an increase in lymphocytes as CON levels rose in their diets, whereas CaPr-supplemented calves showed the opposite effect (interaction, p = 0.05). Supplementation of CaPr decreased total protein (TP, p = 0.03) and albumin (ALB, p < 0.01) serum concentrations, with lower concentrations observed in 20CaPr + 50. CaPr supplementation reduced (p = 0.01) total cholesterol (TCHO) levels. An interaction between CaPr and CON level (p = 0.02) was observed since TCHO levels remained consistently low at higher CON levels. Glucose was decreased with increasing levels of CON (p = 0.02) but not (p = 0.85) for CaPr-supplemented calves. NoCaPr + 50 and NoCaPr + 70 increased (p = 0.05) ALB concentration. Gamma glutamyltransferase levels increased (p = 0.05) with increasing CON levels irrespective of CaPr supplementation. Comparing the profit within the same CON level in the diet, CaPr treatments yielded higher income, with the largest difference in profit observed when CaPr was supplemented at 50% CON level (USD 29 more/calf). In conclusion, CaPr supplementation proves to be an effective strategy for enhancing growth performance and dietary energy among high-risk beef calves, resulting in greater economic returns. The groups that received CaPr demonstrated superior profitability, particularly in calves fed diets with lower CON levels. Under the conditions in which this experiment was carried out, the optimal response occurred when the low-CON diet (50%) was supplemented with CaPr.

Key determinants of adaptive strategies of goats to a 2-day nutritional challenge during early lactation

Little is known about the key determinants of the physiological adaptations to environmental challenges and how these determinants interact. We evaluated how the response/recovery profiles to a short-term nutritional challenge during early lactation are affected by early-life nutritional strategies in dairy goats divergently selected for functional longevity. We used 72 females, split into two cohorts, daughters of Alpine bucks divergently selected for functional longevity. The females from the two lines were fed with two divergent diets, normal vs low-energy, from weaning until the middle of first gestation, and then fed with the same standard diet. Individual BW, body condition score, morphology, and plasma samples were collected from birth to first kidding. The adaptative physiological strategy to a nutritional challenge was assessed via a 2-day feed restriction challenge, during early lactation, which consisted of a five-day control period on a standard lactation diet followed by a 2-day challenge with straw-only feeding and then a 10-day recovery period on a standard lactation diet. During the challenge, DM intake, BW, milk yield (MY), and plasma and milk metabolite composition were recorded daily. Linear mixed-effects models were used to analyze all traits, considering the individual nested in the cohort as a random effect and the 2 × 2 treatments (i.e., line and rearing diet) and litter size as fixed effects. Linear mixed-effects models using a piecewise arrangement were used to analyze the response/recovery profiles to nutritional challenge. Random parameters estimated for each individual, using the mixed-effects models without the fixed effects of rearing diet and genetic line, were used in a stepwise model selection based on R2 to identify key determinants of an individual's physiological adaptations to environmental challenges. Differences in stature and body reserves created by the two rearing diets diminished during late gestation and the 5-day control period. Genetic line did not affect body reserves during the rearing phase. Rearing diet and genetic line slightly affected the recovery profiles of evaluated traits and had no effects on prechallenge and response to challenge profiles. The prekidding energy status measures and MY before challenge were selected as strong predictors of variability in response-recovery profiles of milk metabolites that have strong links with body energy dynamics (i.e., isoCitrate, ß-hydroxybutyrate, choline, cholesterol, and triacylglycerols; R2 = 35%). Our results suggested that prekidding energy status and MY are key determinants of adult resilience and that rearing diet and genetic line may affect adult resilience insofar as they affect the animals' energy status.

Responses of selected plasma metabolites to a two-day nutritional challenge of goats divergently selected for functional longevity

Understanding the extent to which genetics × environment plays a role in shaping individual strategies to environmental challenges is of considerable interest for future selection of more resilient animals. Accordingly, the objective of this study was to evaluate the metabolic responses to a nutritional challenge of goats divergently selected for functional longevity based on plasma metabolites and the repeatability of these responses across 2 experimental farms and years. We carried out 6 different experimental trials from years 2018 to 2022 (4 trials on site Bourges (2018-21) and 2 trials (2021-22) on site Grignon) in which 267 first kidding goats, daughters of Alpine bucks divergently selected for functional longevity, longevity plus (n = 137), and longevity minus (n = 130), were exposed to a 2-d nutritional challenge in early lactation. The experiments consisted of a 5 or 7-d control period (pre-challenge) on a standard lactation diet followed by a 2-d nutritional challenge with straw-only feeding and then a 7 or 10-d recovery period on a standard lactation diet, for site Bourges and Grignon, respectively. During the challenge plasma metabolite composition was recorded daily. Linear mixed-effects models were used to analyze all traits, considering the individual as a random effect and the 2x2 treatments (i.e., genetic line and year nested in site) and litter size as fixed effects. The linear mixed-effects model using a piecewise arrangement was used to analyze the response/recovery profiles to the nutritional challenge. Random parameters estimated for each individual, using the mixed-effects models without the fixed effects of genetic line, were used in a Sparse Partial Least Square Discriminant Analysis (sPLS-DA) to compare the goat metabolism response to the challenge on a multivariate scale. The plasma metabolites, glucose, β-hydroxybutyrate (BHB), and nonesterified fatty acids (NEFA), and urea concentrations responded to the 2-d nutritional challenge. Selection for functional longevity did not affect plasma glucose, NEFA, BHB, and urea response/recoveries to a 2-d nutritional challenge. However, site, trial, and litter size affected these responses. Moreover, the plasma metabolites seem not to fully recover to prechallenge levels after the recovery phase. The sPLS-DA analysis did not discriminate between the 2 longevity lines. We observed meaningful between-individuals' variability in plasma BHB, especially on the prechallenge and rate of response and rate of recovery from the 2-d nutritional challenge (CV = 26.2%, 36.1%, and 41.2%, repeatability = 0.749, 0.322, and 0.741, respectively). Plasma NEFA recovery from challenge also demonstrated high between-individuals' variability (CV = 16.4%, repeatability = 0.323). Selection for functional longevity did not affect plasma metabolites responses to a 2-d nutritional challenge in dairy goats. Plasma NEFA and BHB response/recovery presented high between-individuals' variability, indicating individual adaptative characteristics to nutritional challenges not related to the environmental conditions but to inherent individual characteristics.

Short-term responses of meat ewes facing an acute nutritional challenge in early-mid lactation

Simulating a consequence of a climate change event on feed availability, responses of Mediterranean meat ewes facing an acute undernutritional challenge (CHA; i.e., fed only low nutritional value cereal straw) were evaluated at a sensitive physiological stage (i.e., early suckling). Forty Romane ewes were chosen at early-mid pregnancy (around 2 mo) according to parity (20 primiparous, PRIM; 20 multiparous, MULT); feed efficiency genetic line of their sires (residual feed intake [RFI]; efficient, RFI-, n = 10 per parity; inefficient, RFI+, n = 10 per parity); litter size (i.e., bearing twins, diagnosed by ultrasonography); body weight (BW, kg) and body condition score (BCS) (initial BW and BCS [mean ± SD]: 51.6 ± 7.41 kg; 2.5 ± 0.20, respectively; representing flock' averages per parity). Effects on dry matter intake (DMI), ewes' BW and BCS, subcutaneous dorsal fat thickness (DFT), energy metabolism (plasma non-esterified fatty acids [NEFA], β-hydroxybutyrate (β-OHB), glucose, urea, triiodothyronine [T3]), and lambs' growth (BW and average daily gain [ADG]; g/d) were examined before, during and after CHA. Individuals' profiles of the response-recovery to CHA were described using a piecewise mixed-effects model. The fixed effect of parity and genetic line and the random effect of individual (ewe) were considered. A linear mixed-effects model was fitted to explore the effects on lambs' growth. The 2-d straw-only CHA had significant effects on most of the recorded parameters. Meaningful drops and recoveries were observed on ewes' DMI, BW, and DFT with effect on postchallenge levels. BW, BCS, DFT, or DMI were also affected by parity (MULT > PRIM) but not by genetic line. Plasma NEFA, β-OHB, glucose, urea, and T3 responded well to CHA with drops in T3, urea, and glucose levels, whereas NEFA and β-OHB significantly increased after CHA. MULT ewes presented sharper β-OHB recovery from CHA than PRIM (P ≤ 0.05). With this study, we provide tangible and necessary data for an emerging field of research. Our results give new insights into how such a short and abrupt CHA affects some key zootechnical and physiological parameters, and to what extent the impacts of CHA and the ewes' response-recovery are influenced. It also revealed potential between-individual differences in the adaptive capacities of ewes, which require further exploration.

Relationship between feed efficiency and resilience in dairy ewes subjected to acute underfeeding

Selection of dairy sheep based on production levels has caused a loss of rusticity, which might compromise their future resilience to nutritional challenges. Although refocusing breeding programs toward improved feed efficiency (FE) is expected, more-efficient ewes also seem to be more productive. As a first step to examine the relationship between FE and resilience in dairy sheep, in this study we explored the variation in the response to and the recovery from an acute nutritional challenge in high-yielding Assaf ewes phenotypically divergent for FE. First, feed intake, milk yield and composition, and body weight changes were recorded individually over a 3-wk period in a total of 40 sheep fed a total mixed ration (TMR) ad libitum. Data were used to calculate their FE index (FEI, defined as the difference between the actual and predicted intake estimated through net energy requirements for maintenance, production, and weight change). The highest and lowest FE ewes (H-FE and L-FE groups, respectively; 10 animals/group) were selected and then subjected to the nutritional challenge (i.e., withdrawing the TMR and limiting their diet only to the consumption of straw for 3 d). Afterward, sheep were fed again the TMR ad libitum. Temporal patterns of variation in performance traits, and ruminal fermentation and blood parameters were examined. A good consistency between FEI, residual feed intake, and feed conversion ratio was observed. Results supported that H-FE were more productive than L-FE sheep at similar intake level. Average time trends of milk yield generated by a piecewise model suggest that temporal patterns of variation in this trait would be related to prechallenge production level (i.e., H-FE presented quicker response and recovery than L-FE). Considering all studied traits, the overall response to and recovery from underfeeding was apparently similar or even better in H-FE than in L-FE. This would refute the initial hypothesis of a poorer resilience of more-efficient sheep to an acute underfeeding. However, the question remains whether a longer term feed restriction might impair the ability of H-FE ewes to maintain or revert to a high-production status, which would require further research.

Differentiation of Hair Sheep Breeds Based on the Physiological and Blood Biochemical Changes in Response to Different Stressors Using Multivariate Analysis Techniques

Physiological and blood measurement changes due to high heat load, restricted feed intake, and limited drinking water availability in 135 animals of three hair sheep breeds (Dorper, Katahdin, and St. Croix) were subjected to multivariate analysis techniques. The objective of this analysis was to evaluate the ability of these variables to separate individual hair sheep into groups based on adaptation characteristics in response to three physiological stressors and identify variables with greater discriminatory power. There were 16, 8, and 13 physiological and blood variables obtained from high heat load, restricted feed consumption, and water intake studies, respectively, for multivariate analysis. Physiological variables such as respiration rate, rectal and skin temperature, and panting score were measured only in the heat stress study. The results of the cluster and canonical discriminant analyses showed the presence of wide divergence (p < 0.05) between St. Croix and other breeds in their responses to high heat loads and restricted-feed- and -water-intake conditions. Dorper and Katahdin were grouped (p > 0.05) together based on the changes in physiological variables, which were separated (p < 0.05) from those of St. Croix as a resilient group. The stepwise discriminant analysis indicated that skin temperature, panting score, rectal temperature, respiration rate, and blood urea nitrogen and oxygen concentrations were the significant (p < 0.05) discriminating variables in clustering individual sheep into groups based on their responses to the high-heat-stress condition. Under the limited feed intake condition, the significant (p < 0.05) traits responsible for the separation of St. Croix from Dorper and Katahdin were blood triglyceride and cholesterol concentrations, whereas blood hemoglobin, osmolality, protein, and albumin were most important discriminating variables under the limited water intake condition. In conclusion, the results of the present study suggest that the stress responses of Dorper and Katahdin are similar and different from that of St. Croix. This finding can be useful information for future decisions in developing climate-resilient sheep through selective breeding.

Characterization of fatty acid compositions in longissimus thoracis muscle and identification of candidate gene and SNPs related to polyunsaturated fatty acid in Hu sheep

Fatty acid (FA) composition contributes greatly to the quality and nutritional value of lamb meat. In the present study, FA was measured in longissimus thoracis (LT) muscles of 1,085 Hu sheep using gas chromatography. Comparative transcriptomic analysis was conducted in LT muscles to identify differentially expressed genes (DEGs) between six individuals with high polyunsaturated fatty acids (H-PUFA, 15.27% ± 0.42%) and six with low PUFA (L-PUFA, 5.22% ± 0.25%). Subsequently, the single nucleotide polymorphisms (SNPs) in a candidate gene PLIN2 were correlated with FA traits. The results showed a total of 29 FA compositions and 8 FA groups were identified, with the highest content of monounsaturated fatty acids (MUFA, 46.54%, mainly C18:1n9c), followed by saturated fatty acids (SFA, 44.32%, mainly C16:0), and PUFA (8.72%, mainly C18:2n6c), and significant correlations were observed among the most of FA traits. Transcriptomic analyses identified 110 upregulated and 302 downregulated DEGs between H-PUFA and L-PUFA groups. The functional enrichment analysis revealed three significant Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and 17 gene ontology (GO) terms, in which regulation of lipolysis in adipocytes, the AMPK signaling pathway, and the PPAR signaling pathway may play important roles in FA metabolism and biosynthesis. In addition, weighted gene co-expression network analysis (WGCNA) identified 37 module genes associated with PUFA-related traits. In general, PLIN1, LIPE, FABP4, LEP, ACACA, ADIPOQ, SCD, PCK2, FASN, PLIN2, LPL, FABP3, THRSP, and ACADVL may have a great impact on PUFA metabolism and lipid deposition. Four SNPs within PLIN2 were significantly associated with FA. Of those, SNP1 (g.287 G>A) was significantly associated with C18:1n9c and MUFA, and SNP4 (g.7807 T>C) was significantly correlated with PUFA (C18:3n3). In addition, the combined genotype of SNP1 (g.287 G>A), SNP3 (g.7664 T>C), and SNP4 (g.7807 T>C) were significantly correlated with C16:1, C17:0, C18:1C6, PUFA (C18:3n3, C22:6n3), and n-6/n-3 PUFA. These results contribute to the knowledge of the biological mechanisms and genetic markers involved in the composition of FA in Hu sheep.

Meta-analysis across Nellore cattle populations identifies common metabolic mechanisms that regulate feed efficiency-related traits

Background

Feed efficiency (FE) related traits play a key role in the economy and sustainability of beef cattle production systems. The accurate knowledge of the physiologic background for FE-related traits can help the development of more efficient selection strategies for them. Hence, multi-trait weighted GWAS (MTwGWAS) and meta-analyze were used to find genomic regions associated with average daily gain (ADG), dry matter intake (DMI), feed conversion ratio (FCR), feed efficiency (FE), and residual feed intake (RFI). The FE-related traits and genomic information belong to two breeding programs that perform the FE test at different ages: post-weaning (1,024 animals IZ population) and post-yearling (918 animals for the QLT population).

Results

The meta-analyze MTwGWAS identified 14 genomic regions (-log10(p -value) > 5) regions mapped on BTA 1, 2, 3, 4, 7, 8, 11, 14, 15, 18, 21, and 29. These regions explained a large proportion of the total genetic variance for FE-related traits across-population ranging from 20% (FCR) to 36% (DMI) in the IZ population and from 22% (RFI) to 28% (ADG) in the QLT population. Relevant candidate genes within these regions (LIPE, LPL, IGF1R, IGF1, IGFBP5, IGF2, INS, INSR, LEPR, LEPROT, POMC, NPY, AGRP, TGFB1, GHSR, JAK1, LYN, MOS, PLAG1, CHCD7, LCAT, and PLA2G15) highlighted that the physiological mechanisms related to neuropeptides and the metabolic signals controlling the body's energy balance are responsible for leading to greater feed efficiency. Integrated meta-analysis results and functional pathway enrichment analysis highlighted the major effect of biological functions linked to energy, lipid metabolism, and hormone signaling that mediates the effects of peptide signals in the hypothalamus and whole-body energy homeostasis affecting the genetic control of FE-related traits in Nellore cattle.

Conclusions

Genes and pathways associated with common signals for feed efficiency-related traits provide better knowledge about regions with biological relevance in physiological mechanisms associated with differences in energy metabolism and hypothalamus signaling. These pleiotropic regions would support the selection for feed efficiency-related traits, incorporating and pondering causal variations assigning prior weights in genomic selection approaches.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08671-w.

Comparative transcriptome analysis of goat (Capra hircus) adipose tissue reveals physiological regulation of body reserve recovery after the peak of lactation

Adipose tissue is the energy storage organ providing energy to other tissues, including mammary gland, that supports the achievement of successive lactation cycles. Our objective was to investigate the ability of goats to restore body fat reserves by comparing lipogenic enzyme activities and by transcriptomic RNA-Seq data at two different physiological stages, mid- and post-lactation. Key lipogenic enzyme activities were higher in goat omental adipose tissue during mid-lactation (74 days in milk) than during the post-lactation period (300 days postpartum). RNA-Sequencing analysis revealed 19,271 expressed genes in the omental adipose tissue. The comparison between adipose transcriptome analysis from mid- and post-lactation goats highlighted 252 differentially expressed genes (p_adj < 0.05) between these two physiological stages. The differential expression of 11 genes was confirmed by RT-qPCR. Functional genomic analysis revealed that 31% were involved in metabolic processes among which 38% in lipid metabolism. Most of the genes involved in lipid synthesis and those in lipid transport and storage were upregulated in adipose tissue of mid- compared to post-lactation goats. In addition, adipose tissue plasticity was emphasized by genes involved in cellular signaling and tissue integrity. Network analyses also highlighted three key regulators of lipid metabolism (LEP, APOE and HNF4A) and a key target gene (VCAM1). The greatest lipogenic enzyme activities with the upregulation of genes involved in lipid metabolism highlighted a higher recovery of lipid reserves after the lactation peak than 4 months post-lactation. This study contributes to a better understanding of the molecular mechanisms controlling the body lipid reserves management during the successive lactations.

Body Condition Score Change throughout Lactation Utilizing an Automated BCS System: A Descriptive Study

Simple Summary

The aim of this study was to implement a commercially available automated body condition scoring (ABCS) camera system to collect data for developing a predictive equation of body condition dynamics throughout the lactation period. The body condition score can vary depending on many factors relative to a specific cow. Lactation number, DIM, disease status, and 305d-predicted-milk-yield (305PMY) were significant factors to create a multivariate prediction model for automatic body condition scores throughout lactation.

Abstract

Body condition scoring (BCS) is a traditional visual technique often using a five-point scale to non-invasively assess fat reserves in cattle. However, recent studies have highlighted the potential in automating body condition scoring using imaging technology. Therefore, the objective was to implement a commercially available automated body condition scoring (ABCS) camera system to collect data for developing a predictive equation of body condition dynamics throughout the lactation period. Holstein cows (n = 2343, parity = 2.1 ± 1.1, calving BCS = 3.42 ± 0.24), up to 300 days in milk (DIM), were scored daily using two ABCS cameras mounted on sort-gates at the milk parlor exits. Scores were reported on a 1 to 5 scale in 0.1 increments. Lactation number, DIM, disease status, and 305d-predicted-milk-yield (305PMY) were used to create a multivariate prediction model for body condition scores throughout lactation. The equation derived from the model was: ABCS_ijk = 1.4838 − 0.00452 × DIM_i − 0.03851 × Lactation number_j + 0.5970 × Calving ABCS_k + 0.02998 × Disease Status(neg)_l − 1.52 × 10⁻⁶ × 305PMY_m + e_ijklm. We identified factors which are significant for predicting the BCS curve during lactation. These could be used to monitor deviations or benchmark ABCS in lactating dairy cows. The advantage of BCS automation is that it may provide objective, frequent, and accurate BCS with a higher degree of sensitivity compared with more sporadic and subjective manual BCS. Applying ABCS technology in future studies on commercial dairies may assist in providing improved dairy management protocols based on more available BCS.

Genetic differentiation of mainland-island sheep of Greece: Implications for identifying candidate genes for long-term local adaptation

In Greece, a number of local sheep breeds are raised in a wide range of ecological niches across the country. These breeds can be used for the identification of genetic variants that contribute to local adaptation. To this end, 50k genotypes of 90 local sheep from mainland Greece (Epirus, n = 35 and Peloponnesus, n = 55) were used, as well as 147 genotypes of sheep from insular Greece (Skyros, n = 21), Lemnos, n = 36 and Lesvos, n = 90). Principal components and phylogenetic analysis along with admixture and spatial point patterns analyses suggested genetic differentiation of 'mainland-island' populations. Genome scans for signatures of selection and genome-wide association analysis (GWAS) pointed to one highly differentiating marker on OAR4 (FST = 0.39, FLK = 21.93, FDR p-value = 0.10) that also displayed genome wide significance (FDR p-value = 0.002) during GWAS. A total number of 6 positional candidate genes (LOC106990429, ZNF804B, TEX47, STEAP4, SRI and ADAM22) were identified within 500 kb flanking regions around the significant marker. In addition, two QTLs related to fat tail deposition are reported in genomic regions 800 kb downstream the significant marker. Based on gene ontology analysis and literature evidence, the identified candidate genes possess biological functions relevant to local adaptation that worth further investigation.

Effect of dietary protein on growth performance, and serum biochemical index in late pregnant Hu ewes and their offspring

The purpose of this study was to investigate the effects of different protein levels in late pregnancy on ewe and lamb growth performance, serum biochemical indexes. Thirty-three ewes (46.4 ± 1.38 kg initial weight) were randomly divided into 3 groups, with 11 ewes in each group. The protein levels of three diets formulated to provide components to meet 10.00 MJ/kg ME requirements diets were: 10.12%, 11.26%, 12.4%. Ewes were raised from the 90th day of pregnancy to the end of delivery, and the lambs were weaned at 60 days. Dietary protein levels had significant effects on blood urea nitrogen, glucose, ammonia nitrogen and triglyceride of ewes (p < 0.05). The height, chest depth, chest circumference, straight crown hip length and curved crown hip length of lambs decreased at first and then increased with the increase of protein. The body length, chest circumference, head width and head length of weaned lambs decreased at first and then increased with the increase of protein. The results showed that when the dietary protein level was increased to 12.4%, the amino acid, glucose and fat metabolism of ewes were affected. The body size development of lambs was better than 10.12% and 11.26% proteins.

Influence of Different Lactation Stages on Circadian Rhythmicity of Metabolic Biomarkers in Dairy Cows: A Pilot Study

Simple Summary

Circadian rhythms are present in most species and play an important role in their metabolism. Metabolic biomarkers, which are commonly used to assess the health status, are also affected by those rhythms. In this study, we investigate the influence of lactation and time on four metabolic biomarkers in dairy cows. Our findings provide new insights into the physiology of circadian rhythms in dairy cows, which enables novel metabolic monitoring approaches.

Abstract

Currently, subclinical metabolic imbalances at the individual cow and herd level are detected by measuring biomarkers in single blood samples. However, diurnal variations have not been fully described yet but need to be considered when sampling for a robust ad consistent analysis. The study describes the influence of lactation phases on circadian rhythms and diurnal variations for non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), total bilirubin (tBIL) and aspartate aminotransferase (AST) in dairy cows. In an observational pilot study, we used 16 clinically healthy Simmental dairy cows subdivided in four different lactation stages (dry-off, fresh, high and late lactating). Every cow was monitored for 24 h, with blood sampling and assessment of clinical parameters every 2 h. Time and lactation stage influence the concentration of the biomarkers NEFA, BHB and tBIL in serum. Further, circadian rhythmicity was found in high lactating cows for NEFA peaking at 5:39 am and BHB peaking at 4:20 pm. We suggest blood sampling for single-point measurements within three hours after the first feeding until two hours after the last feeding of the day. The results provide a new insight into the physiology of circadian rhythms in dairy cows and enable improved metabolic monitoring.

Residual carbon dioxide as an index of feed efficiency in lactating dairy cows

High feed costs make feed conversion efficiency a desirable target for genetic improvement. Residual feed intake (RFI), calculated as the difference between observed and predicted intake, is a commonly used estimate of feed efficiency. However, determination of feed efficiency in dairy herds is challenging due to difficulties in measuring feed intake of individual animals reliably. Using residual CO₂ (RCO₂) production as an estimate of feed efficiency would allow ranking the cows according to feed efficiency, provided that CO₂ production is closely related to heat production and feed intake. The objective of this study was to evaluate the potential of RCO₂ as an index of feed efficiency using data from respiration calorimetry studies (289 cow per period observations). Heat production was precisely predicted from CO₂ production [root mean square error (RMSE)] adjusted for random effects was 1.5% of observed mean]. Dry matter intake (DMI) was better predicted from energy-corrected milk (ECM) yield and CO₂ production than from ECM yield and body weight in the model (adjusted RSME = 0.92 vs. 1.39 kg/d). Residual CO₂ production estimated as the difference between actual CO₂ production and that predicted from ECM yield, metabolic body weight was closely related to RFI (adjusted RMSE = 0.42) that was calculated as the difference between actual DMI and that predicted from ECM, metabolic body weight, and energy balance (EB). When the cows were categorized in 3 groups of equal sizes on the basis of RCO₂ (low, medium, and high), low RCO₂ cows had lower DMI, RFI, methane production and intensity (g/kg ECM), and heat production, but higher efficiency of metabolizable energy utilization for lactation than high RCO₂ cows. When RFI was predicted from RCO₂, the residuals (observed - predicted) were negatively related to EB and digestibility. Predicting RFI with a 2-variable model based on RCO₂ and digestibility, adjusted RMSE decreased to 0.23 kg/d, and residuals were not significantly related to EB. The cows in low RCO₂ group had a higher energy digestibility than the cows in the high RCO₂ group, and differences in EB were observed between the groups. Error of the model predicting residual ECM production from RCO₂ was 1.41 kg/d. The residuals were positively related to ECM yield and energy digestibility. Predicting residual ECM from RCO₂ and ECM yield decreased adjusted RMSE to 1.07 kg/d, and further to 0.78 kg/d when digestibility was included in the 2-variable model. It is concluded that RCO₂ has a potential for ranking individual cows based on feed efficiency.

Feed Quality and Feeding Level Effects on Faecal Composition in East African Cattle Farming Systems

Simple Summary

Sub-Saharan cattle are often exposed to a feed reduction caused by a seasonal lack of forage, which was investigated in the first experiment. The supplementation of roughage-based diets with sweet potato vine silage and urea molasses blocks is recommended to improve the growth of heifers, in particular, which was investigated in the second experiment. Across all data, the fungal C/bacterial C ratio was positively related to nitrogen and negatively to neutral detergent fiber concentrations in feces. This diet-induced shift in the fecal microbial community is relevant for the fertilizer quality of cattle faces after application to soil.

Abstract

Effects of feeding levels below maintenance requirements of metabolizable energy (MER) and of feed supplementation on fecal nutrient and microbial C concentrations were evaluated. In experiment 1, Rhodes grass hay only was offered to Boran steers at 80%, 60%, and 40% of individual MER, while steers at 100% MER additionally received a concentrated mixture. This reduction in MER decreased N, increased fungal C but did not affect bacterial C concentrations in feces. In experiment 2, Holstein × Boran heifers were offered a poor-quality roughage diet without supplement, with sweet potato vine silage or with a urea-molasses block. These two supplements did not affect the fecal chemical composition or fungal C but increased bacterial C concentrations in feces. Across all data, the fungal C/bacterial C ratio was positively related to N and negatively to neutral detergent fiber concentrations in feces, indicating diet-induced shifts in the fecal microbial community.

Evaluation of the net energy for lactation system and estimation of the energy requirements of dairy cows based on a comprehensive analysis of feeding trials

Respiration experiments with high-yielding dairy cows in Northern Ireland have shown higher energy maintenance requirements than those used in the requirements standards of, e.g. France, UK, USA and Germany. Therefore, the current net energy for lactation (NEL) system of Germany was tested by comparing measured NEL intake with calculated NEL requirements based on a comprehensive dataset from feeding trials conducted at nine research institutions in Germany, Austria and Switzerland. The relationship between NEL requirements and NEL intake is described by the equation: N E L r e q u i r e m e n t s M J / d = 26 . 6 ± 0 . 4 + 0 . 82 ± 0 . 004 ⋅ N E L i n t a k e M J / d w i t h C o e f f i c i e n t   o f   D e t e r m i n a t i o n   R 2 = 0 . 677 , R o o t   M e a n   S q u a r e   E r r o r   R M S E   = 15 . 9   M J   N E L . The equation indicates a systematic over-estimation of NEL requirements in the lower performance range and an under-estimation at higher energy intake levels. A multiple regression analysis was conducted by calculating metabolisable energy (ME) requirements [MJ/d] using metabolic body size (MBS) [kg^0.75], milk energy performance (LE) [MJ/d] and body weight change (BWC) [kg/d]: ​ ​ ​ ​ ​ ​ ​ ME intake ( MEI ) [ MJ ] =0 . 651 ( ± 0 . 004 ) ⋅ MBS+1 . 37 ( ± 0 . 006 ) ⋅ LE + 16 . 6 ( ± 0 . 31 ) ⋅ BWC with R 2 = 0. 717 , RMSE=24 . 0   MJ . These results indicate that the energy maintenance requirements are markedly higher than presumed in the feed evaluation systems commonly in use but confirm the results from Northern Ireland (0.600-0.660 MJ ME/kg^0.75 MBS). ME efficiency for lactation is also higher (k_L = 1/1.37 = 0.73) than that used in the systems and is also similar to the results of Northern Ireland with 0.64-0.69. The energy contribution of BWC derived by this equation is 12.1 MJ/kg (16.6 · 0.73) and distinctly lower than that of 21-25 MJ/kg presumed by the feeding standards, e.g. in Germany. Further, maintenance requirements were linked to milk yield (energy corrected milk (ECM) [kg/d]), as is practiced in the standard Australian energy system: ​ ​ ​ ​ ​ ​ ​ ( MEI ) [ MJ ] =0 . 640  + 0 . 0070 ⋅  ECM) ] ⋅ MBS+1 . 12) ⋅ LE   + 16 . 7 ⋅  BWC with R 2 = 0. 719 , RMSE=24 . 0   MJ . These results demonstrate that maintenance energy requirements are partly dependent on milk yield. A differentiated analysis by stage of lactation showed that the regressions coefficients for MBS, LE and BWC change with lactation month; however, these findings apply especially to the first lactation months (i.e. in phases of intensive mobilisation).

Rabbit Lines Divergently Selected for Total Body Fat Content: Correlated Responses on Growth Performance and Carcass Traits

The aim of this experiment was to study the effect of divergently selected rabbits for total body fat content (fat index) on growth performance and carcass traits. The fat index was determined at 10 weeks of age by computed tomography and lasted for four consecutive generations. The rabbits with the lowest fat index belonged to the lean line and those of the highest values belonged to the fat line. At generation four, 60 rabbits/line were housed in wire-mesh cages and fed with commercial pellet ad libitum from weaning (5 w of age) to slaughtering (11 w of age). Growth performance, dressing out percentage and carcass adiposity were measured. The lean line showed a better feed conversion ratio (p < 0.001) than the fat line. Furthermore, the carcass of the lean rabbits had the highest proportion of fore (p < 0.020) and hind (p < 0.006) parts. On the contrary, rabbits of the fat line had the highest carcass adiposity (p < 0.001). The divergent selection for total body fat content showed to be effective for both lean and fat lines. Selection for lower total body fat content could be useful for terminal male lines, while the selection for higher total body fat content could be an advantage for rabbit does in providing fat (energy) reserves.

Genetic correlations between energy status indicator traits and female fertility in primiparous Nordic Red Dairy cattle

Inclusion of feed efficiency traits into the dairy cattle breeding programmes will require considering early lactation energy status to avoid deterioration in health and fertility of dairy cows. In this regard, energy status indicator (ESI) traits, for example, blood metabolites or milk fatty acids (FAs), are of interest. These indicators can be predicted from routine milk samples by mid-IR reflectance spectroscopy (MIR). In this study, we estimated genetic variation in ESI traits and their genetic correlation with female fertility in early lactation. The data consisted of 37 424 primiparous Nordic Red Dairy cows with milk test-day records between 8 and 91 days in milk (DIM). Routine test-day milk samples were analysed by MIR using previously developed calibration equations for blood plasma non-esterified FA (NEFA), milk FAs, milk beta-hydroxybutyrate (BHB) and milk acetone concentrations. Six ESI traits were considered and included: plasma NEFA concentration (mmol/l) either predicted by multiple linear regression including DIM, milk fat to protein ratio (FPR) and FAs C10:0, C14:0, C18:1 cis-9, C14:0 * C18:1 cis-9 (NEFAFA) or directly from milk MIR spectra (NEFAMIR), C18:1 cis-9 (g/100 ml milk), FPR, BHB (mmol/l milk) and acetone (mmol/l milk). The interval from calving to first insemination (ICF) was considered as the fertility trait. Data were analysed using linear mixed models. Heritability estimates varied during the first three lactation months from 0.13 to 0.19, 0.10 to 0.17, 0.09 to 0.14, 0.07 to 0.10, 0.13 to 0.17 and 0.13 to 0.18 for NEFAMIR, NEFAFA, C18:1 cis-9, FPR, milk BHB and acetone, respectively. Genetic correlations between all ESI traits and ICF were from 0.18 to 0.40 in the first lactation period (8 to 35 DIM), in general somewhat lower (0.03 to 0.43) in the second period (36 to 63 DIM) and decreased clearly (-0.02 to 0.19) in the third period (64 to 91 DIM). Our results indicate that genetic variation in energy status of cows in early lactation can be determined using MIR-predicted indicators. In addition, the markedly lower genetic correlation between ESI traits and fertility in the third lactation month indicated that energy status should be determined from the first test-day milk samples during the first 2 months of lactation.

Genetic parameters for milk fatty acid composition of Holstein in Korea

Objective

Milk fatty acid (FA) is a main nutritional component that markedly effects human health. Intentional modification of the FA profile has the potential to improve milk quality. This study aimed at the factors affecting elevated FA levels and the estimation of the genetic parameters for milk FAs in the Korean Holstein population.

Methods

Total 885,249 repeated test-day milk records including, milk yield, saturated fatty acids (SFA), polyunsaturated fatty acids (PUFA), monounsaturated fatty acids (MUFA), total unsaturated fatty acids (TUFA), fat and protein percentages were analyzed using CombiFoss FT+ system (Foss Analytical A/S, Denmark). Genetic parameters were estimated by the restricted maximum likelihood procedure based on the repeatability model using the Wombat program.

Results

The FA profile varies along with the lactation and the energy balance (EB). With the negative EB in early lactation, mobilization of body fat reserves elevates the desirable FA levels. As a result of that, milk quality is increased by means of nutritionally and usability aspects during the early lactation. Moreover, heritability estimates for SFA, MUFA, PUFA, TUFA were 0.33, 0.42, 0.37, 0.41 respectively. According to the parity wise heritability analysis, first parity cows had relatively lower heritability for SFAs (0.19) than later parities (0.28).

Conclusion

Genetic parameters indicated that FAs were under stronger genetic control. Therefore, we suggest implementing animal breeding programs towards improving the milk FA profile.

Urine metabolome alterations in malnutrition and the impact of glycerol or rumen-protected choline chloride supplementation in advanced pregnant ewes

The objective of this study was to explore the metabolic profiles of pregnancy malnutrition induced by feed restriction (FR) and the counteracting effects of glycerol and rumen-protected choline chloride supplementation. Two feeding trials were conducted. In the first experiment, twenty pregnant Hu sheep carrying multiple fetuses with a gestation period of 108 d were randomly divided into two groups. The ewes in the control (CON) group were offered 100 % of their nutritional requirements as recommended by the National Research Council (NRC), while the FR group was offered 30 % of feed intake of CON for 15 d. In the second experiment, eighteen pregnant Hu sheep were offered a feed intake comprising 30 % of the NRC-recommended nutritional requirements twice daily. The sheep were randomly divided into three groups: the FR group in the second experiment (FR2), with no supplementation, the glycerol (GLY) group, which received 40 ml of glycerol per d, and the rumen-protected choline chloride (RPC) group, which received 10 g of rumen-protected choline chloride per d for 9 d. In the first experiment, the urine metabolome of sixteen ewes showed significant difference between the CON group and FR group. Compared with the CON group, FR decreased the level of d-glucose, lactic acid, levoglucosan, α-ketoglutarate, phosphohydroxypyruvic acid, glucose 6-phosphate and the methyl donors, while increasing the level of pyruvate, fumaric acid and carnitines in urine. Both the GLY and RPC treatments counteracted some of these changes and modulated the urine metabolome in advanced pregnant ewes suffering from malnutrition.

Milk metabolites as noninvasive indicators of nutritional status of mid-lactation Holstein and Montbéliarde cows

The objective was to investigate the effects of feed restriction on concentrations of selected milk metabolites in mid-lactation Holstein and Montbéliarde cows and to explore their correlations with energy balance and classic plasma and milk indicators of nutritional status. Eight Holstein and 10 Montbéliarde cows (165 ± 21 d in milk) underwent 6 d of feed restriction during which feed allowance was reduced to meet 50% of their net energy for lactation (NE_L) requirements. The experiment was divided in 4 periods: control (CON; d -3 to -1), restriction (RES; d 1 to 6), wk 1 (W1; d 7 to 13), and wk 2 (W2; d 14 to 18) after refeeding at ad libitum intake. Intake, milk production, energy balance and plasma metabolites were used to validate the feed restriction model. Concentrations of 7 milk metabolites: β-hydroxybutyrate (BHB), glucose, glucose-6-phosphate, isocitrate, glutamate, uric acid, and free amino groups were measured in morning milk samples, and fatty acids were measured in pooled p.m. and a.m. samples. Feed restriction induced a negative energy balance (-42.5 ± 4.4 MJ/d), increased plasma nonesterified fatty acids and BHB, and decreased plasma glucose concentrations. Feed restriction increased milk glucose-6-phosphate and isocitrate (+38% and +39%, respectively) and decreased milk BHB, glucose, glutamate, uric acid and free amino group concentrations (-20%, -57%, -65%, -42%, and -14%, respectively), compared with pre- restriction. Milk concentrations of medium-chain fatty acids (e.g., sum of C10 to C15) decreased and those of long chain (e.g., 18:0, cis-9 18:1) increased during restriction. Breed differences were not detected for the majority of variables. All studied milk metabolites were significantly correlated with energy balance (Spearman correlation = 0.48, 0.63, -0.31, -0.45, and 0.61 for BHB, glucose, glucose-6-phosphate, isocitrate, and glutamate, respectively). Milk glucose and glutamate showed the strongest correlations with plasma metabolites and milk FA associated with lipomobilization. These results suggest that milk metabolites may be used as noninvasive indicators of negative energy balance and metabolic status of dairy cows.

Lipid Catabolism in Starved Yak Is Inhibited by Intravenous Infusion of β-Hydroxybutyrate

Simple Summary

Yak, which is the predominant and semi-domesticated livestock on the Qinghai-Tibet Plateau, suffers severe starvation and body weight reduction in the cold season because of the harsh highland environment. Lipids are important energy sources to starvation animals. β-hydroxybutyrate (BHBA) that is derived from lipid decomposition as the primary ketone body is with the function not only to provide energy for animals as energy materials, but also regulate lipid metabolism as signaling molecular. However, the effects of starvation and BHBA on lipid metabolism and its mechanism are still unclear for ruminant animals. Herein, we investigated the effects of starvation and intravenous infusion of BHBA solution on Yak growth, serum biochemistry, hormones, subcutaneous adipocyte morphology, fatty acid composition, activity of enzymes related to lipid metabolism, and signal pathway. The results showed that starvation promoted lipid catabolism and BHBA infusion up-regulated the mRNA expression of receptor GPR109A in subcutaneous adipose tissue, inhibited the Cyclic adenosine monophosphate(cAMP)/Protein kinase A (PKA)/cAMP-responsive element binding protein (CREB) signaling pathway, and inhibited lipolysis. Our study was beneficial for enriching the nutrition regulation theory of yaks and improving their growth potential.

Abstract

Lipid is the chief energy source for starved animals. β-hydroxybutyrate (BHBA) is the main ketone body produced by lipid decomposition. In Chinese hamster ovary (CHO) cell experiment, it was found that BHBA could be used not only as an energy substance, but also as a ligand of GPR109A for regulating lipid metabolism. However, whether BHBA can regulate lipid metabolism of yaks, and its effective concentration and signal pathway are not clear. This study investigated the effects and mechanism of starvation and BHBA on the lipid metabolism of yak. Eighteen male Jiulong yaks were selected and then randomly divided into three groups: normal feeding group (NG), starvation group (SG), and starvation with BHBA infusion group (SBG). The yaks in the NG group were freely fed during the trial, while the yaks in the SG and SBG groups fasted; from 7th to 9th days of the experiment, the NG and SG were infused continuous with 0.9% normal saline and SBG was infused 1.7 mmol/L BHBA solution respectively. The blood samples were collected on the 0th, 1st, 3rd, 5th, 7th, and 9th day of experiment. The subcutaneous adipose tissue of all the yaks in this study were taken from live bodies after infusion. Serum glucose, lipid metabolites, hormone concentrations, and mRNA and protein expressions of key factors of lipid metabolism and signaling pathway in subcutaneous adipose tissue were measured. The results showed that, as compared with NG, starvation significantly reduced the body weight of yak in SG, and significantly increased the concentration of BHBA in serum and the mRNA expression of PKA and CREB1 in subcutaneous adipose tissue, while the mRNA expression of MEK, PKC, ERK1/2, the area of adipocytes, and the proportion of saturated fatty acid were decreased. Whereas, further increase of BHBA concentration through infusion promoted the mRNA expression of GPR109A receptor in the subcutaneous adipose tissue of SBG, inhibited the mRNA expression of AC and PKA, and decreased the phosphorylation protein abundance of CREB1, and significantly increased the diameter and area of adipocytes. These findings suggest that starvation led to enhanced lipid catabolism in yaks. An increasing BHBA concentration could increase the mRNA expression of GPR109A receptor in subcutaneous adipose tissue and inhibit the cAMP/PKA/CREB signaling pathway and lipid decomposition.

Insulin signaling and insulin response in subcutaneous and retroperitoneal adipose tissue in Holstein cows during the periparturient period

Adipose tissue response to endocrine stimuli, such as insulin, is crucial for metabolic adaptation at the onset of lactation in dairy cows. However, the exact molecular mechanisms behind this response are not well understood. Thus, the aim of this study was to determine the dynamics in protein expression and phosphorylation of key components in insulin signaling in subcutaneous (SCAT) and retroperitoneal (RPAT) adipose tissues of Holstein dairy cows. Furthermore, by ex vivo examinations, response to insulin was assessed in SCAT and RPAT at different time points during the periparturient period. Biopsy samples were taken 42 d prepartum, and 1, 21, and 100 d postpartum. Insulin and glucose concentrations were measured in blood serum in consecutive serum samples from d -42 until d +100. After parturition, the majority of the key components were downregulated in both adipose tissues but recovered by d +100. The extent of hormone-sensitive lipase phosphorylation increased postpartum and remained high throughout the experimental period. Strong differences in molecular response were observed between the 2 depots. The RPAT expressed a remarkably greater extent of AMP-activated kinase phosphorylation compared with SCAT, indicating that AMP-activated kinase as an energy sensor is highly active particularly in RPAT in times of energy scarcity. Consequently, this depot expressed a greater extent of hormone-sensitive lipase phosphorylation over the whole experimental period. Insulin response after parturition appeared to be greater in RPAT too, due to the significantly greater expression of the insulin receptor at d +21 and +100. Although insulin concentrations in plasma were low postpartum, the depot-specific changes in molecular modulation of insulin signaling and insulin response suggested that both adipose tissue depots studied were contributing to the periparturient homeorhetic adaptation, although most likely to a different extent.

Small Ruminants: Farmers' Hope in a World Threatened by Water Scarcity

Simple Summary

Water is one of the most important nutrients to livestock. It is so essential that more than half the volume of the animal's body is water. However, its availability is threatened by the irreversible changes in climate, which has culminated into reduced rainfall in most regions of the world. Such an increasing threat to regular water supply, and by extension to food security and livelihood has forced a shift from large to small ruminant production, especially in regions experiencing low rainfall, with farmers taking advantage of their adaptive process and efficiency of water use. Small ruminants, especially desert goats, can adaptively survive in water-limited areas while trekking long distance in search of feed and they will regain any weight loss at the next watering point. Further research is needed on adaptive indigenous breeds of small ruminants since tolerance to water scarcity is breed dependent, so that improvements can be made through effective selection and breeding program.

Abstract

The availability and sustainability of suitable and good quality drinking water is a global concern. Such uncertainties threaten livestock production with an attendant ripple effect on food security. Small ruminants, including sheep and goats, appear to be promising to smallholder farmers in solving this problem because of their ability to survive in water-limited areas and harsh environment when compared with large ruminants. Their small body size is also seen as an advantage, because less water will be required for proper digestion and feed utilization. Therefore, this review will provide information regarding the adaptive responses of small ruminants on thermoregulation, blood metabolites, immune status, drug pharmacokinetics, reproduction and hormonal indices during the period of water stress. Adaptable and indigenous breeds are known to be more tolerant to water stress than selected breeds. A drop in feed intake and weight reduced respiratory rate and increased concentration of blood metabolites are the general effects and/or observations that are encountered by small ruminants during the period of water stress. The concept of water tolerance either as deprivation and/or restriction of indigenous and adaptable breeds of small ruminants is gaining ground in research studies around the world. However, more research, however, seeking to explore water tolerance capacity of adaptable breeds especially in arid and water limiting areas are still needed.

Digesta passage and nutrient digestibility in Boran steers at low feed intake levels

The present study evaluated the effects of energetic undernutrition on liquid and solid digesta passage and on nutrient digestibility as well as their interdependencies. Using a 4 x 4 Latin square design, 12 growing Boran steers (183 ± 15.2 kg live weight) were allocated to four levels of metabolizable energy (ME) supply fixed at 100, 80, 60 and 40% of individual maintenance energy requirements (MER) during four experimental periods. Each period comprised three weeks of adaptation, two weeks of data collection and two weeks of recovery. Diets MER80, MER60 and MER40 only consisted of Rhodes grass hay (RGH), whereas diet MER100 contained (as fed) 83% RGH, 8% cotton seed meal and 9% sugarcane molasses. Feed intake differed between treatments (p < .001) and ranged from 40 ± 0.6 g dry matter (DM) per kg of metabolic weight (kg^0.75 ) in MER40 to 81 ± 1.3 g DM in MER100. Digestibility of neutral and acid detergent fibre (NDF, ADF) was highest at MER80, whereas rumen retention time of liquid and solid digesta was longest at MER40. The correlation of rumen retention time of liquid and solid digesta with the digestibility of proximate diet components was weak but positive, whereas the correlation of liquid and solid rumen retention time with quantitative feed and nutrient intake was strong (p < .01) and negative. Our results suggest that tropical cattle are able to buffer a moderate energy deficit by prolonging rumen retention time of digesta and hence improve diet digestibility. Conversely, a severe energy deficit cannot be buffered by digestive adaptation mechanisms and will inevitably lead to productivity losses.

Long-term effects of prior diets, dietary transition and pregnancy on adipose gene expression in dairy heifers

Adipose tissue is highly involved in whole-body metabolism and is the main site for lipid synthesis, storage and mobilization in ruminants. Therefore, knowledge about adipose tissue responses to different diets is important, especially in growing heifers as the feeding regimes of replacement heifers affect their future success as dairy cows. However, at gene expression level such knowledge is limited. As part of a larger feed trial, adipose tissue biopsies from 24 Norwegian Red heifers were collected at 12 months of age (12MO) and at month seven of gestation (PREG) and analyzed by next-generation mRNA sequencing. Between these two sampling points, all heifers had gone through a successful conception and a feed change from four dietary treatments of high or low energy (HE/LE) and protein (HP/LP) content (treatments LPHE, HPHE, LPLE and HPLE) to a low-energy, low-protein pregnancy feed given to all animals. Gene expression differences between different feed treatments at 12MO are described in an earlier publication from our group. The main objectives of this study were to investigate the long-term effects of diets differing in protein and energy density level on gene expression in adipose tissue of growing replacement dairy heifers. To achieve this, we examined the post-treatment effects between the treatment groups at month seven of gestation; 6 months after the termination of experimental feeding, and the long-term gene expression changes occurring in the adipose tissue between 12MO and PREG. Post-treatment group comparisons showed evidence of long-term effects of dietary treatment on adipose gene expression. Differences between protein treatments were smaller than between energy treatments. Adipose gene expression changes from 12MO to PREG were much larger for the HE than the LE treatments and seemed to mostly be explained by the characteristics of the diet change. 97 genes displayed a unidirectional expression change for all groups from 12MO to PREG, and are considered to be treatment-independent, possibly caused by pregnancy or increased age. This study provides candidate genes and key regulators for further studies on pregnancy preservation (TGFB1, CFD) and metabolic regulation and efficiency (PI3K, RICTOR, MAP4K4,) in dairy cattle.

Maternal Metabolic Demands Caused by Pregnancy and Lactation: Association with Productivity and Offspring Phenotype in High-Yielding Dairy Ewes

Simple Summary

This study assessed the effects of metabolic load imposed by pregnancy and lactation on productivity and offspring performance in high-yielding dairy sheep. Productivity was assessed in terms of offspring and maternal milk yield, metabolic profile, and body condition. Our results show that maternal productivity and lamb body weight and growth are not compromised by pregnancy and lactation because dairy sheep, when appropriately managed, seem to be able to cover metabolic demands of pregnancy and high milk production without losing productivity.

Abstract

Pregnancy and lactation, especially when concurrent, create a rather metabolically demanding situation in dairy ruminants, but little is known about their effects on offspring phenotype and milk yield. Here, we evaluated the impact of pregnancy and lactation on the metabolic traits and productive performance of Lacaune dairy sheep and their offspring. Productive performance was measured in terms of milk yield, body weight (BW), body condition score (BCS), and size. Productivity was assessed during mid-pregnancy (75 ± 5 d) and late pregnancy (142 ± 4 d) and at 52 ± 5 d in the postpartum period. During pregnancy, high-yielding ewes had higher BW, BCS, plasma glucose, cholesterol, β-OHB, and NEFA than low-yielding ewes, but lower levels of lactate and urea. High-yielding animals had lower BCS after lambing, but their lambs showed greater growth. Productivity during lactation was affected by ewe age and parity: Mature ewes (but not maiden sheep) whose BCS increased steeply during pregnancy yielded more milk in the subsequent lactation than those whose BCS did not increase. Lamb BW and size were positively associated with milk yield in the subsequent lactation. Mature ewes had higher yields than maiden sheep, and mature ewes with multiple pregnancies produced more milk than those with singleton pregnancies. Ewes with male singleton pregnancies also showed higher yield than those with female singletons. These results demonstrate that high-yielding dairy sheep, when appropriately fed and managed, can adequately cover the metabolic demands of pregnancy and high milk production (even when concurrent) without losing productivity.

Effect of diet and type of pregnancy on plasma metabolic response in sheep and its further effect on lamb performance

This trial evaluated the individual and interactional effects of diet and type of pregnancy (twin or single) on plasma metabolic response in ewes and their lambs from late pre-partum to late post-partum. Thus, a flock of 18 Ile de France breed sheep, consisting of 8 twin-bearing and 10 single-bearing ewes, were allocated to one of two groups according to their diet, either based on ad libitum naturalized pasture hay (NPH) or red clover hay (RCH), from d 45 pre-partum to d 60 post-partum. Plasma samples were collected at different times to determine albumin, cholesterol, total protein and urea, plus glucose and β-hydroxybutyrate (BHB) concentration in ewes. The data was processed using the lme4 package for R, and SPSS Statistics 23.0 for Windows. The results showed that both diet and type of pregnancy influenced the metabolic profile in ewes, showing an inverse relationship between single- and twin-bearing ewes regarding glucose and especially BHB proportions from pre-partum to birth. During post-partum, higher urea concentrations were observed in twin- and single-bearing ewes fed RCH in contrast to those fed NPH, as a result of the higher-quality forage offered to ewes. Regarding lambs, the diet and type of pregnancy influenced the total protein and urea levels, where an inverse relationship at birth and early post-partum between albumin and cholesterol vs. total protein and urea was detected, reflecting a trend (P value between 0.06 and 0.07) to a better performance by groups of single lambs, especially those from single-bearing ewes fed RCH. Finally, under the conditions of this study, the maternal diet and type of pregnancy influenced the plasma metabolic response in ewes and their lambs, affecting the lamb performance especially at birth.

Effects of Body Condition and Concentrate Proportion of the Ration on Mobilization of Fat Depots and Energetic Condition in Dairy Cows during Early Lactation Based on Ultrasonic Measurements

Simple Summary

During early lactation, cows face metabolic challenges. They experience a negative energy balance as energy intake increases more slowly than energy output with milk rises. To compensate for that energy deficit, higher amounts of concentrate are offered. Additionally, cows are able to extract energy from body fat by lipid mobilization. Excessive body fat mobilization, however, leads to metabolic disorders. Therefore, high-conditioned cows are suggested to have a more pronounced lipid mobilization. The intention of the present study was to examine the change of various fat depots during the transition period depending on body condition and energy supply with ultrasonic measurements. Body condition loss after calving usually interpreted as mobilization of subcutaneous adipose tissue was not different between cows with a higher or lower body condition score. However, ultrasonic measurements detected a more pronounced mobilization of subcutaneous adipose tissue in higher conditioned animals. In contrast, inner fat depots were mobilized similarly between cows. Higher concentrate feed proportions led to a less pronounced negative energy balance. A less pronounced negative energy balance would have been expected to decrease lipid mobilization. However, this relation could not be verified in the present study. This demonstrates that sonography-based methods provide a clearer picture of metabolic conditions.

Abstract

The aim of this study was to evaluate energy metabolism and lipid mobilization via ultrasonic measurements (USM), considering inner fat depots, in lactating dairy cows differing in body condition score (BCS) and fed rations with low (35% at dry matter basis; C₃₅) or high (60% at dry matter basis; C₆₀) concentrate feed proportions postpartum. Sixty pluriparous German Holstein cows were arranged in a 2 × 2 factorial design from d 42 antepartum (relative to calculated calving) until d 120 postpartum. Animals were divided into a group with a lower (initial BCS = 3.1 ± 0.38 SD; BCS_L) and a group with a higher (initial BCS = 3.83 ± 0.41 SD; BCS_H) BCS. Due to higher dry matter intake C₆₀ groups reached the positive energy balance earlier, whereas C₃₅ groups had a more pronounced negative energy balance. Although this would suggest a more pronounced mobilization of C₃₅ groups the USM revealed no differences between feeding groups. Differences in BCS between both BCS groups remained almost the same over the trial. This was not reflected in ultrasonic data, as lipid mobilization was higher in higher conditioned cows. These findings demonstrate the extended possibilities of USM to depict metabolic processes.

Influence of Maternal Factors (Weight, Body Condition, Parity, and Pregnancy Rank) on Plasma Metabolites of Dairy Ewes and Their Lambs

Pregnancy and lactation are challenging states that affect maternal and lamb health. In Lacaune dairy sheep, we evaluated the impact of parity, pregnancy rank, and body condition on body weight and the condition of ewes and lambs in mid-pregnancy (75 ± 5 d), in late pregnancy (142 ± 4d), and postpartum (52 ± 5d pp). Maternal age was associated with initial decreases, followed by increases, in body weight and condition. After lambing, both mature and maiden ewes lost weight and body condition. Maternal indices of glucose, protein, and lipid metabolism were within physiological values during pregnancy, but postpartum values depended on maternal parity and pregnancy rank, with multiple-pregnant ewes showing a postpartum increase in glucose and maiden sheep a postpartum increase in plasma cholesterol concentration. Male lambs were heavier than female lambs at birth, and lambs born to mothers with higher body condition scores were heavier. Lambs born as singletons were heavier than those born in litters. Maternal age and pregnancy rank did not influence lamb metabolic indicators. Sex affected plasma concentrations of glucose, triglycerides, and cholesterol. Maternal metabolic indicators showed minimal effects on lamb phenotype. These results suggest that, when appropriately fed, dairy sheep can cover the metabolic demands of pregnancy and milk production, regardless of age and pregnancy rank.

Effect of Chinese herbal medicine on kinetics of plasma phenylalanine, tyrosine and whole body protein synthesis in sheep

The aim of this study was to evaluate the effect of feeding decoction of a traditional nourishing Chinese herbal medicine formula on rates of plasma phenylalanine and tyrosine turnover and whole body protein synthesis in sheep. Ruminal fermentation characteristics and blood metabolites were also determined. Six sheep were subjected to either mixed hay (MH‐diet, as control) or MH‐diet supplemented with 2% of Chinese herbal medicine (mixture of Astragalus root, Angelica root, and Atractylodes rhizome; CHM‐diet) in a crossover design for each of 3‐week period. The isotope dilution of [²H₅]phenylalanine and [²H₂]tyrosine was performed as a primed‐continuous infusion to measure plasma phenylalanine and tyrosine kinetics. Concentrations of total volatile fatty acid, acetate, and propionate in the rumen tended to be higher (p < 0.10), and the pH value was lower (p = 0.04) for the CHM‐diet than the MH‐diet. Turnover rates of plasma phenylalanine and tyrosine tended to be higher (p < 0.10) for the CHM‐diet than the MH‐diet. Furthermore, whole body protein synthesis was greater (p = 0.04) for the CHM‐diet compared with the MH‐diet. The Chinese herbal medicine improved rumen fermentation and enhanced protein metabolism in sheep. Hence, it is suggested that the decoction of Chinese herbal medicine formula could be considered as a potential feed additive for ruminant production.

Feed deprivation in Merino and Terminal sired lambs: (2) the metabolic response under pre-slaughter conditions and impact on meat quality and carcass yield

Under current Australian industry pre-slaughter guidelines, lambs may be off feed for up to 48 h before slaughter. The purpose of this study was to examine what proportion of circulating metabolites at slaughter are due to stress and feed deprivation and if this response differs between Merino and Terminal genotypes. In addition the effect of feed deprivation on carcass weight and meat quality was examined. Jugular blood samples were collected from 88 Merino and Terminal sired lambs at rest and at slaughter following 24, 36 and 48 h of feed deprivation and plasma analysed for glucose, lactate, non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB). From the same carcasses hot carcass weight (HCWT) were measured as well as a suite of meat quality traits measured such as M. longissimus lumborum (loin) and M. semitendinosus pH at 24 h postmortem. Loin samples were also analysed for intramuscular fat content and Warner-Bratzer Shear Force. Merino sired lambs had a higher NEFA response compared to Terminal sired lambs at slaughter after 24, 36 and 48 h of feed deprivation, with NEFA levels up to 35% higher than previously reported in the same animals at rest in animal house conditions, whereas BHOB response to feed deprivation was not affected by sire type (P&gt;0.05) and similar to previously reported at rest. In addition to the metabolic effects, increasing feed deprivation from 36 h was associated with a 3% reduction in HCWT and dressing percentage as well as causing increased ultimate pH in the M. semitendinosus in Merino sired lambs. Findings from this study demonstrate that Merino and Terminal sired lambs differ in their metabolic response to feed deprivation under commercial slaughter conditions. In addition, commercial feed deprivation appears to have a negative effect on ultimate pH and carcass weight and warrants further investigation.

Feed deprivation in Merino and Terminal sired lambs: (1) the metabolic response under resting conditions

The aim of this study was to examine the metabolic response to feed deprivation up to 48 h in low and high yielding lamb genotypes. It was hypothesised that Terminal sired lambs would have decreased plasma glucose and increased plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB) concentrations in response to feed deprivation compared to Merino sired lambs. In addition, it was hypothesised that the metabolic changes due to feed deprivation would also be greater in progeny of sires with breeding values for greater growth, muscling and leanness. Eighty nine lambs (45 ewes, 44 wethers) from Merino dams with Merino or Terminal sires with a range in Australian Sheep Breeding Values (ASBVs) for post-weaning weight (PWT), post-weaning eye muscle depth and post-weaning fat depth (PFAT) were used in this experiment. Blood samples were collected via jugular cannulas every 6 h from time 0 to 48 h of feed deprivation for the determination of plasma glucose, NEFA, BHOB and lactate concentration. From 12 to 48 h of feed deprivation plasma glucose concentration decreased (P &lt; 0.05) by 25% from 4.04 ± 0.032 mmol/l to 3.04 ± 0.032 mmol/l. From 6 h NEFA concentration increased (P &lt; 0.05) from 0.15 ± 0.021 mmol/l by almost 10-fold to 1.34 ± 0.021 mmol/l at 48 h of feed deprivation. Feed deprivation also influenced BHOB concentrations and from 12 to 48 h it increased (P &lt; 0.05) from 0.15 ± 0.010 mmol/l to 0.52 ± 0.010 mmol/l. Merino sired lambs had a 8% greater reduction in glucose and 29% and 10% higher NEFA and BHOB response, respectively, compared to Terminal sired lambs (P &lt; 0.05). In Merino sired lambs, increasing PWT was also associated with an increase in glucose and decline in NEFA and BHOB concentration (P &lt; 0.05). In Terminal sired lambs, increasing PFAT was associated with an increase in glucose and decline in NEFA concentration (P &lt; 0.05). Contrary to the hypothesis, Merino sired lambs showed the greatest metabolic response to fasting especially in regards to fat metabolism.

Characterization of the endocannabinoid system in subcutaneous adipose tissue in periparturient dairy cows and its association to metabolic profiles

Adipose tissue (AT) plays a major role in metabolic adaptations in postpartum (PP) dairy cows. The endocannabinoid (eCB) system is a key regulator of metabolism and energy homeostasis; however, information about this system in ruminants is scarce. Therefore, this work aimed to assess the eCB system in subcutaneous AT, and to determine its relation to the metabolic profile in peripartum cows. Biopsies of AT were performed at 14 d prepartum, and 4 and 30 d PP from 18 multiparous peripartum cows. Cows were categorized retrospectively according to those with high body weight (BW) loss (HWL, 8.5 ± 1.7% BW loss) or low body weight loss (LWL, 2.9 ± 2.5% BW loss) during the first month PP. The HWL had higher plasma non-esterified fatty acids and a lower insulin/glucagon ratio PP than did LWL. Two-fold elevated AT levels of the main eCBs, N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG), were found 4 d PP compared with prepartum in HWL, but not in LWL cows. AT levels of the eCB-like molecules oleoylethanolamide, palmitoylethanolamide, and of arachidonic acid were elevated PP compared with prepartum in all cows. The abundance of monoglyceride lipase (MGLL), the 2-AG degrading enzyme, was lower in HWL vs. LWL AT PP. The relative gene expression of the cannabinoid receptors CNR1 and CNR2 in AT tended to be higher in HWL vs. LWL PP. Proteomic analysis of AT showed an enrichment of the inflammatory pathways’ acute phase signaling and complement system in HWL vs. LWL cows PP. In summary, eCB levels in AT were elevated at the onset of lactation as part of the metabolic adaptations in PP dairy cows. Furthermore, activating the eCB system in AT is most likely associated with a metabolic response of greater BW loss, lipolysis, and AT inflammation in PP dairy cows.

The contribution of hormone sensitive lipase to adipose tissue lipolysis and its regulation by insulin in periparturient dairy cows

Hormone sensitive lipase (HSL) activation is part of the metabolic adaptations to the negative energy balance common to the mammalian periparturient period. This study determined HSL contribution to adipose tissue (AT) lipolysis and how insulin regulates its activity in periparturient dairy cows. Subcutaneous AT (SCAT) samples were collected at 11 d prepartum (dry) and 11 (fresh) and 24 d (lactation) postpartum. Basal and stimulated lipolysis (ISO) responses were determined using explant cultures. HSL contribution to lipolysis was assessed using an HSL inhibitor (CAY). Basal lipolysis was higher in SCAT at dry compared with fresh. CAY inhibited basal lipolysis negligibly at dry, but at fresh and lactation it reduced basal lipolysis by 36.1 ± 4.51% and 43.1 ± 4.83%, respectively. Insulin inhibited lipolysis more pronouncedly in dry compared to fresh. Results demonstrate that HSL contribution to basal lipolysis is negligible prepartum. However, HSL is a major driver of SCAT lipolytic responses postpartum. Lower basal lipolysis postpartum suggests that reduced lipogenesis is an important contributor to fatty acid release from SCAT. Loss of adipocyte sensitivity to the antilipolytic action of insulin develops in the early lactation period and supports a state of insulin resistance in AT of cows during the first month postpartum.

Mammary gland and milk fatty acid composition of two dairy goat breeds under feed-restriction

Goat dairy products are an important source of animal protein in the tropics. During the dry season, pasture scarcity leads animals to lose up to 40% of their body weight, a condition known as Seasonal Weight Loss (SWL) that is one of the major constraints in ruminant production. Breeds with high tolerance to SWL are relevant to understand the physiological responses to pasture scarcity so they could be used in programs for animal breeding. In the Canary Islands there are two dairy goat breeds with different levels of tolerance to SWL: the Palmera, susceptible to SWL; and the Majorera, tolerant to SWL. Fat is one of the milk components most affected by environmental and physiological conditions. This study hypothesises that feed-restriction affects Majorera and Palmera breeds differently, leading to different fatty acid profiles in the mammary gland and milk. An interaction between breed and feed-restriction was observed in the mammary gland. Feed-restriction was associated with an increase in oleic acid and a decrease in palmitic acid percentage in the Palmera breed whereas no differences were observed in the Majorera breed. Palmitic and oleic acids together constituted around 60% of the total fatty acids identified, which suggests that Palmera breed is more susceptible to SWL. In milk, feed-restriction affected both breeds similarly. Regarding the interaction of the breed with the treatment, we also observed similar responses in both breeds, but this influence affects only around 2% of the total fatty acids. In general, Majorera breed is more tolerant to feed-restriction.

Responses of body fat mobilization to isoproterenol or epinephrine challenge in adult cows: influence of energy level, breed, and body fatness

The sustainability of livestock production systems facing climatic or economic changes is linked in part to the potential of the female ruminants to adapt to feeding constraints through metabolic and hormonal regulation, notably responses of body fat mobilization, depending on adipose tissue (AT) lipolysis. Our hypothesis was that these responses could change according to genotype (breed) and body fatness. Six fat, nonpregnant, nonlactating Charolais cows, six fat Holstein cows, and six lean Holstein cows were used in a 2 × 2 crossover design with two treatments (underfeeding or overfeeding, at 62% [low] or 128% [high] of maintenance energy requirements [MER], respectively) and two periods. Isoproterenol (ISO, a nonselective β-adrenergic agonist) or epinephrine (EPI, a β- and α2-adrenergic agonist) was injected (6 nmol/kg of lean mass). Blood samples were collected regularly from -20 to 75 min after the injection and then were analyzed for NEFA, glycerol, glucose, and L-lactate. Underfeeding greatly increased (P < 0.001) basal plasma NEFA concentrations (+467%, +264%, and +600% for fat Charolais, fat Holstein, and lean Holstein cows, respectively). For each drug, underfed cows had higher NEFA or glycerol responses to adrenergic challenges than overfed cows. Fat Charolais cows had higher basal plasma NEFA (P < 0.05) concentrations (+64.9%) than fat Holstein cows. The plasma NEFA or glycerol response at 5 min (P < 0.05) was higher for fat Charolais than for fat Holstein cows, whatever the injected drug. Basal plasma lactate concentration and lactate response to ISO or EPI were higher (P < 0.05) for fat Charolais cows than for fat Holstein cows. Fat Holstein cows had higher (P < 0.01) basal glycerol (+18.4%) than lean Holstein cows. This increase could be linked to the increased AT mass. ISO increased more lipolytic responses in fat than in lean Holstein cows, whereas EPI increased more these responses in lean than in fat Holstein cows (drug × fatness interaction), suggesting an increased antilipolytic effect due to α2-AR stimulation in fat cows. Breed had a significant effect on basal and stimulated fat mobilization as well as lactate concentrations, suggesting that the Charolais breed could be more sensitive to stress.

Divergent breeding values for fatness or residual feed intake in Angus cattle. 4. Fat EBVs’ influence on fatness fluctuation and supplementary feeding requirements

The productivity of 500 Angus cows, divergently selected for either rib fat or residual feed intake (RFI) based on BREEDPLAN estimated breeding values (EBVs) and managed under two levels of nutrition (stocking rates), was evaluated. The study examined the effects of genetic line, nutrition and weaning history on profiles for weight, rib fat depth, fatness (rib fat depth adjusted for weight) and supplementary feed requirements from just before the first joining as heifers through to the weaning of their third calf. Cows gained both weight and fat as they grew older. Observed fluctuations in weight and rib fat depth, within each year, were associated with pasture availability and physiological demands. Cows that did not wean a calf in a given year became heavier and fatter than cows that did; and they remained so when they calved the following year. High-fat and High-RFI were always fatter and lighter than Low-fat and Low-RFI cows, respectively. The difference in rib fat and fatness between High- and Low-RFI lines (P < 0.001) was similar to, although slightly greater than, the difference between High- and Low-fat lines (P = 0.048) reflecting differences in rib fat EBVs between High-RFI (3.2 ± 1.47) and Low-RFI (–0.7 ± 1.3) compared with High-fat (1.1 ± 0.78) and Low-fat (–1.4 ± 0.67). Cows on High-Nutrition were heavier and fatter than those on Low-Nutrition (P < 0.001) but there were no significant interactions between genetic line and nutrition (P > 0.05). Supplementary feeding threshold was reached earlier by Low-fat and Low-RFI cows than their counterparts. Calculations based on the data in the present paper estimate that if cows lose condition at a rapid rate (1 condition score/month), then a cow with an extra 1 mm rib fat EBV would take 7.5 days longer to reach the same supplementary feeding threshold. Fat EBVs can, therefore, be a useful tool in assisting beef producers to match genotype to their production system.

Earwax metabolomics: An innovative pilot metabolic profiling study for assessing metabolic changes in ewes during periparturition period

Important metabolic changes occur during transition period of late pregnancy and early lactation to meet increasing energy demands of the growing fetus and for milk production. The aim of this investigation is to present an innovative and non-invasive tool using ewe earwax sample analysis to assess the metabolic profile in ewes during late pregnancy and early lactation. In this work, earwax samples were collected from 28 healthy Brazilian Santa Inês ewes divided into 3 sub-groups: 9 non-pregnant ewes, 6 pregnant ewes in the last 30 days of gestation, and 13 lactating ewes ≤ 30 days postpartum. Then, a range of metabolites including volatile organic compounds (VOC), amino acids (AA), and minerals were profiled and quantified in the samples by applying headspace gas chromatography/mass spectrometry, high performance liquid chromatography/tandem mass spectrometry, and inductively coupled plasma-optical emission spectrometry, respectively. As evident in our results, significant changes were observed in the metabolite profile of earwax between the studied groups where a remarkable elevation was detected in the levels of non-esterified fatty acids, alcohols, ketones, and hydroxy urea in the VOC profile of samples obtained from pregnant and lactating ewes. Meanwhile, a significant decrease was detected in the levels of 9 minerals and 14 AA including essential AA (leucine, phenyl alanine, lysine, isoleucine, threonine, valine), conditionally essential AA (arginine, glycine, tyrosine, proline, serine), and a non-essential AA (alanine). Multivariate analysis using robust principal component analysis and hierarchical cluster analysis was successfully applied to discriminate the three study groups using the variations of metabolites in the two stress states (pregnancy and lactation) from the healthy non-stress condition. The innovative developed method was successful in evaluating pre- and post-parturient metabolic changes using earwax and can in the future be applied to recognize markers for diagnosis, prevention, and intervention of pregnancy complications in ewes.