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Light micrograph of subcutaneous adipose tissue stained with haematoxylin and eosin. A; High plane of nutrition had large areas of adipocytes (400×), B; Low plane of nutrition had small pockets of adipocytes (400×)
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Background:
Adipose tissue is a major endocrine organ and is thought to play a central role in the metabolic control of reproductive function in cattle. Plane of nutrition during early life has been shown to influence the timing of puberty in both male and female cattle, though the exact biological mechanisms involved are currently unknown. The ai...
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Context 1
... low plane of nutrition groups, respectively and this trans- lated into a bodyweight difference of 53.8 kg at slaughter between the bulls of the high compared to the low treatment group (160.9 ± 3.98 kg versus 107.1 ± 3.19 kg, respectively; P < 0.001). Adipocyte cell number (291 ± 47.2 cells/1.25 mm 2 versus 7.5 ± 4.0 cells/1.25 mm 2 , P < 0.001; Fig. 1) and cell diameter (36.9 ± 2.89 μm versus 3.7 ± 1.94 μm, P < 0.001) were both greater in the high compared with the low plane of nutrition animals, ...
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Citations
... The genes enriched in fatty acid degradation (CPT1B, ACADM, ECHS1, EHHADH, ACAA1, and ALDH9A1) screened in this study show a trend of down-regulation of their expression, which suggests that fattening can promote fat deposition. English et al. [46] found that differential fat genes in subcutaneous fat from male calves were significantly enriched in the fatty acid degradation pathway under different dietary conditions. Mitochondrial fatty acid β-oxidation is the main pathway of lipid degradation [47]. ...
Yak meat is nutritionally superior to beef cattle but has a low fat content and is slow-growing. The liver plays a crucial role in lipid metabolism, and in order to determine whether different feeding modes affect lipid metabolism in yaks and how it is regulated, we employed RNA sequencing (RNA-seq) technology to analyze the genome-wide differential gene expression in the liver of yaks maintained under different raising systems. A total of 1663 differentially expressed genes (DEGs) were identified (|log2FC| ≥ 0 and p-value ≤ 0.05), including 698 down-regulated and 965 up-regulated genes. According to gene ontology (GO) and KEGG enrichment analyses, these DEGs were significantly enriched in 13 GO terms and 26 pathways (p < 0.05). Some DEGs were enriched in fatty acid degradation, PPAR, PI3K-Akt, and ECM receptor pathways, which are associated with lipid metabolism. A total of 16 genes are well known to be related to lipid metabolism (e.g., APOA1, FABP1, EHHADH, FADS2, SLC27A5, ACADM, CPT1B, ACOX2, HMGCS2, PLIN5, ACAA1, IGF1, FGFR4, ALDH9A1, ECHS1, LAMA2). A total of 11 of the above genes were significantly enriched in the PPAR signaling pathway. The reliability of the transcriptomic data was verified using qRT-PCR. Our findings provide new insights into the mechanisms regulating yak meat quality. It shows that fattening improves the expression of genes that regulate lipid deposition in yaks and enhances meat quality. This finding will contribute to a better understanding of the various factors that determine yak meat quality and help develop strategies to improve yield and quality.
... Like alpaca, signatures of selection for carcass quality traits were detected also in llama. In fact, ARFGEF2 was found to be under selection in dromedary camel and proposed as determinant of camel body weight [48] while other selected loci such as BCL7B, MLXIPL and NDUFAF2 are implied in fat deposition and depth [46,[49][50][51][52]. Two loci associated with animal domestication and behavior traits, were found under selection in llama. ...
Background Alpaca (Vicugna pacos), llama (Lama glama), vicugna (Vicugna vicugna) and guanaco (Lama guanicoe), are the camelid species distributed over the Andean high-altitude grasslands, the Altiplano, and the Patagonian arid steppes. Despite the wide interest on these animals, most of the loci under selection are still unknown. Using whole- genome sequencing (WGS) data we investigated the occurrence and the distribution of Runs Of Homozygosity (ROHs) across the South American Camelids (SACs) genome to identify the genetic relationship between the four species and the potential signatures of selection.
Results A total of 37 WGS samples covering the four species was included in the final analysis. The multi-dimensional scaling approach showed a clear separation between the four species; however, admixture analysis suggested
a strong genetic introgression from vicugna and llama to alpaca. Conversely, very low genetic admixture of the guanaco with the other SACs was found. The four species did not show significant differences in the number, length of ROHs (100-500 kb) and genomic inbreeding values. Longer ROHs (> 500 kb) were found almost exclusively in alpaca. Seven overlapping ROHs were shared by alpacas, encompassing nine loci (FGF5, LOC107034918, PRDM8, ANTXR2, LOC102534792, BSN, LOC116284892, DAG1 and RIC8B) while nine overlapping ROHs were found in llama with twenty-five loci annotated (ERC2, FZD9, BAZ1B, BCL7B, LOC116284208, TBL2, MLXIPL, PHF20, TRNAD-AUC, LOC116284365, RBM39, ARFGEF2, DCAF5, EXD2, HSPB11, LRRC42, LDLRAD1, TMEM59, LOC107033213, TCEANC2, LOC102545169, LOC116278408, SMIM15, NDUFAF2 and RCOR1). Four overlapping ROHs, with three annotated loci (DLG1, KAT6B and PDE4D) and three overlapping ROHs, with seven annotated genes (ATP6V1E1, BCL2L13, LOC116276952, BID, KAT6B, LOC116282667 and LOC107034552), were detected for vicugna and guanaco, respectively.
Conclusions The signatures of selection revealed genomic areas potentially selected for production traits as well as for natural adaptation to harsh environment. Alpaca and llama hint a selection driven by environment as well as by farming purpose while vicugna and guanaco showed selection signals for adaptation to harsh environment. Interesting, signatures of selection on KAT6B gene were identified for both vicugna and guanaco, suggesting a positive effect on wild populations fitness. Such information may be of interest to further ecological and animal production studies.
... Meanwhile, diet affects histotroph proteomes of embryo pre-implantation and understanding the impact may help to improve the conception rates (8). In bull calves of dairy breeds, a high level of early calf-hood nutrition is beneficial for pubertal onset, which is advantageous to facilitating early semen collection (9,10). ...
... Adipose tissue, as a vital node in the inter-organ crosstalk, could mediate the regulation of metabolism in multiple organs and tissues. Meanwhile, the nutritional state affects lipid metabolism and adipokines production, thus regulating a wide range of biological processes (9,11). For instance, lecithin supplementation improved the meat quality in broilers by affecting the lipid metabolism and microbiota (12). ...
... The calves were assigned to different diets (high or low plane of nutrition) under the same feeding management conditions. The dietary components could be referred to in the previous study (9). The feeding process under the condition of high and low dietary nutrient levels is as follows. ...
Background
Substantive evidence has confirmed that nutrition state is associated with health risk and the onset of pubertal and metabolic profile. Due to heterogeneity, adipose tissues in different anatomical positions tend to show various metabolic mechanisms for nutrition. To date, the complicated molecular mechanisms of early calf-hood nutrition on bovine adipose tissue are still largely unknown. This study aimed to identify key genes and functionally enriched pathways associated with early calf-hood nutrition in visceral and subcutaneous adipose tissue.
Results
The RNA-seq data of visceral and subcutaneous adipose tissues of calves feeding on low and high dietary nutrition for more than 100 days were downloaded and analyzed by weighted gene co-expression network analysis (WGCNA). Two modules that positively associated with a low plane of nutrition diet and two modules with a high plane of nutrition diet were identified in the subcutaneous adipose tissue. The blue and yellow modules, most closely associated with low and high nutrition, were selected for the functional enrichment analysis and exploration of hub genes. The results showed that genes in the blue module were significantly enriched in pathways that related to fat metabolism, reproduction, and cell communication. Genes in the yellow module were enriched in pathways related to fat metabolism, reproduction, cell proliferation, and senescence. Meanwhile, the blue and brown modules in visceral adipose tissue were most closely associated with low and high nutrition, respectively. Notably, genes of the blue module were significantly enriched in pathways related to substance metabolism, and genes in the brown module were significantly enriched in energy metabolism and disease pathways. Finally, key genes in subcutaneous adipose tissue for low nutrition (PLCG1, GNA11, and ANXA5) and high nutrition (BUB1B, ASPM, RRM2, PBK, NCAPG, and MKI67), and visceral adipose tissue for low nutrition (RPS5, RPL4, RPL14, and RPLP0) and high nutrition (SDHA and AKT1) were obtained and verified.
Conclusion
The study applied WGCNA to identify hub genes and functionally enriched pathways in subcutaneous and visceral adipose tissue and provided a basis for studying the effect of early calf-hood nutrition on the two adipose tissue types.
... The final extent of adipose tissue development in the body is determined by differentiation of stem cells into mature adipocytes with the early post-natal period particularly important for this effect 19 . Enhanced plane of nutrition during the early-life period in calves has been shown to not only enhance overall growth rates but also contributes to the development of adipose depots 28 . Moreover, enhanced early life nutrition has been shown to be beneficial for subsequent lifelong growth and production potential of an animal 29 . ...
... Moreover, enhanced early life nutrition has been shown to be beneficial for subsequent lifelong growth and production potential of an animal 29 . Lifelong benefits of enhanced nutrition and associated adipogenesis during the early life period may also potentially include enhanced lactogenesis potential 16 , earlier reproductive development 13 and improved carcass composition 30 28 . The latter of which was concerned with investigating the effect of enhanced nutrition in bull calves during early life. ...
... Similarly, as a consequence of their higher plane of nutrition, the adipose tissue of HI calves also displayed greater expression of genes involved in oxidative phosphorylation and mitochondrial energy production. Up-regulation of oxidative phosphorylation genes in the HI group implies an overall greater derivation of energy derived from the ingested dietary nutrients, which could then subsequently result in more energy being available for anabolic purposes within the adipose tissue and concurs with previous finding from our group examining enhanced early life nutrition on the transcriptome of subcutaneous adipose tissue in bull calves 28 . Whilst we have also reported altered expression of genes involved in metabolism and energy production processes in skeletal muscle and liver tissues of Holstein Friesian bulls fed a moderately restricted diet in order to induce compensatory growth in comparison to a non-diet restricted contemporary group 31,32 . ...
Adipose tissue represents not only an important energy storage tissue but also a major endocrine organ within the body, influencing many biochemical systems including metabolic status, immune function and energy homeostasis. The objective of this study was to evaluate the effect of an enhanced dietary intake during the early calfhood period on the transcriptome of visceral adipose tissue. Artificially reared Angus × Holstein–Friesian heifer calves were offered either a high (HI, n = 15) or moderate (MOD, n = 15) plane of nutrition from 3 to 21 weeks of life. At 21 weeks of age all calves were euthanized, visceral adipose harvested and samples subsequently subjected to mRNA sequencing. Plane of nutrition resulted in the differential expression of 1214 genes within visceral adipose tissue (adj. p < 0.05; fold change > 1.5). Differentially expressed genes were involved in processes related to metabolism and energy production. Biochemical pathways including Sirtuin signalling (adj. p < 0.0001) and the adipogenesis pathways (adj. p = 0.009) were also significantly enriched, indicating greater metabolic processing and adipogenesis in the calves on the high plane of nutrition. Results from this study identify novel genes regulating the molecular response of visceral adipose tissue to an improved plane of nutrition during early calfhood.
... ). Des variations de l'adiposité corporelle ou musculaire sont dues à l'âge dans 9 jeux de données, la race dans 8 jeux de données, le sexe dans 3 jeux de données et l'alimentation dans 14 jeux de données. A ce jour et pour les tissus adipeux et musculaire, 7 jeux de données (5 muscle et 2 TA) ont été produits par RNAseq avec comme facteurs de variation de l'adiposité corporelle ou musculaire l'âge pour une étude « muscle »(He et Liu, 2013), la race pour une étude « tissu adipeux »(Jin et al., 2015), et la nutrition pour une étude « tissu adipeux » et quatre études « muscle »(Baldwin, Li, Li, Thomson et Bequette, 2012;Carrillo et al., 2016;English et al., 2018;Keel et al., 2018;Keogh et al., 2016). L'essentiel des données a été obtenu avec des puces à ADN, et essentiellement sur le muscle et ont fait l'objet de 11 publications, certains jeux de données publiés sous forme de GSE n'ont pas donné lieu à une publication. ...
L’équilibre entre les masses des tissus musculaire (TM) et adipeux (TA) conditionne le poids de carcasse et son rendement (rapport TM et TA), mais aussi les qualités sensorielle et nutritionnelle des viandes. Comprendre comment contrôler le rapport des masses de muscle relativement à celle des tissus adipeux reste un enjeu majeur pour les filières de production bovine. Les méthodes omiques ont abondamment été utilisées pour comprendre les mécanismes explicatifs de la variabilité du croît ou de la masse des tissus adipeux et musculaire chez le bovin. Cependant, à partir de cette masse de données, il n’est pas toujours aisé d’extraire ou de générer une information biologique synthétique. L’objectif de ma thèse était donc d’agréger et de ré-analyser des données publiques pour proposer des gènes ou protéines marqueurs de l’adiposité corporelle ou musculaire, compléter les connaissances disponibles ou identifier des manques de données. Pour ce faire, des techniques in silico et expérimentale ont été combinées. La majorité des données disponibles dans les bases publiques concernaient le muscle et étaient des données transcriptomiques, rarement protéomiques. Les résultats de 5 publications comparant le protéome musculaire de bovins divergents pour la teneur en lipides intramusculaires ont été agrégés pour identifier 50 protéines avec des abondances divergentes, dont 9 trouvées dans au moins 2 publications. Ces données ayant été obtenues chez des races précoces, nous avons analysé le protéome d’une race plus tardive. Le muscle Longissimus thoracis de bovins, Rouges des Prés divergents par les adiposités musculaire et corporelle ont été analysés par les techniques de shotgun et de 2DE. Sur les 47 protéines liées significativement aux dépôts adipeux dans le muscle ou la carcasse, 21 étaient communes avec les résultats publiés, et 26 n’avaient jamais été identifiées. En particulier, l’abondance d’APOBEC2 était fortement corrélée à l’adiposité de la carcasse et du muscle.Parmi les données issues de puces à ADN accessibles dans les bases de données publiques, 84 et 12 jeux de données relatifs, respectivement à la croissance musculaire et adipeuse, ont été sélectionnés. En raison de manques dans les métadonnées, seulement 33 (32 « TM », 1 « TA ») d’entre eux ont été rendus comparables par la mise à jour des noms de gène sur le génome bovin actuel (UCD1.2 ; collaboration avec Sigenae). Les données des 32 jeux de données « muscle » ont été catégorisées selon l’âge, la race, le sexe ou l’alimentation. Par catégorie, les données ont été regroupées et analysées par combinaison de valeurs p selon la méthode inverse normale (collaboration avec l’UMR Gabi). Pour la catégorie âge, facteur de variation majeur de la teneur en lipides intramusculaires, nous avons identifié 238 gènes (sur les 715 communs à 10 jeux de données) différentiellement exprimés dans le longissimus dorsi de bovins de 5 races. Parmi ces 238 gènes, 97 étaient différentiels dans au moins 2 des jeux de données analysés individuellement et la méta-analyse. Ils confirmaient par exemple la dynamique de régulation des métabolismes glycolytiques et oxydatif en fonction de l’âge des bovins. 17 gènes ont été identifiés comme différentiel selon l’âge exclusivement dans la méta-analyse. Parmi les gènes identifiés certains sont liés au métabolisme des lipides (APOE, LDLR, MXRA8) et d’autres pourraient induire (YBX1) ou réprimer (MAPK14, YWAH, ERBB2), la différenciation de cellules progénitrices musculaires vers le lignage adipeux. L’intégration de données publiques, notamment par la méta-analyse, a donc augmenté les connaissances sur les mécanismes biologiques et biomarqueurs contribuant au rapport TA/TM. Les relations entre les abondances des molécules identifiées et des critères d’adiposité restent à quantifier dans une perspective de validation des biomarqueurs.
... RNASeq data generated in our own laboratory from calves offered a high compared with moderate plane of nutrition highlight greater mRNA expression of genes involved in cellular energy production and branched chain AA degradation in s.c. adipose tissue in these calves (English et al., 2018c). This was consistent with histological evidence for greater adiposity (number and size of adipocytes) and a lower number of preadipocytes in s.c. ...
... Although no differences in systemic concentrations of protein were detectable, calves offered a high plane of nutrition had a greater abundance of transcripts for adipokines such as leptin and adiponectin in s.c. adipose tissue (English et al., 2018c), concomitant with characteristics of precocious sexual development at 18 wk of age such as greater paired testes weight, seminiferous tubule development, and SC abundance. ...
The advent of genomic selection has accentuated interest in procuring saleable semen from young genetically elite bulls as early in life as possible. However, the timing of availability of semen for commercial use will be determined by the age at which these young animals reach puberty and subsequent sexual maturity. Enhancing early-life nutrition stimulates the functionality of the hypothalamic–pituitary–testicular axis, mediated through complex biochemical interplay between metabolic and neuroendocrine signals and culminating in enhanced testicular growth, steroidogenesis, spermatogenesis, and ultimately, earlier onset of sexual maturation. Indeed, recent evidence indicates that the timing of sexual precocity, which is dictated by an early gonadotropin rise (8–20 wk of age) in the bull, is determined by prevailing metabolic status during calfhood and is not compensable even where prior undernutrition is followed by dietary augmentation. However, despite this, the precise neuronal mechanisms regulating these developmental processes remain to be elucidated for the bull. Although early-life nutrition clearly affects the sexual maturation process, there is little evidence for latent effects on postpubertal semen characteristics. Equally, postpubertal fertility, measured as in vitro fertilization and early embryogenesis, is not influenced by nutritional status during early life. Current efforts employing high throughput nucleic acid and proteomic sequencing and targeted immunofluorescence coupled with systems biology–based gene network analyses can provide further insight on how nutrition may mediate the biochemical interaction between neuroendocrine and testicular cellular processes. Such information can be harnessed to identify potential genomic targets as part of genomically assisted breeding programs as well as facilitate development of strategic nutritional regimens to optimize sexual maturation and subsequent semen availability from genetically elite young bulls.
... Total RNA was extracted from each tissue sample using RNeasy Universal plus Kit (Qiagen, Manchester, UK). The quantity and quality of the RNA isolated was determined using the same procedure as described by English et al. 20 . RNA integrity number (RIN) for all samples was greater than 8. ...
... RNA integrity number (RIN) for all samples was greater than 8. Further RNA library preparation, sequencing and analysis were carried out as described by English et al. 20 . Sixty (20 calves × 3 tissues) cDNA libraries were prepared from high quality RNA using an Illumina TruSeq RNA Sample Preparation kit v2 following the manufacturer's instructions (Illumina, San Diego, CA, USA). ...
The aim of this study was to investigate the effect of early calf-hood nutrition on the transcriptomic profile of the arcuate nucleus of the hypothalamus, anterior pituitary and testes in Holstein-Friesian bulls. Holstein-Friesian bull calves with a mean (±S.D.) age and bodyweight of 19 (±8.2) days and 47.5 (±5.3) kg, respectively, were offered a high (n = 10) or low (n = 10) plane of nutrition in order to achieve an overall growth rate of 1.2 and 0.5 kg/day. At 126 (±3) days of age, calves were euthanized, hypothalamus (arcuate region), anterior pituitary and testicular parenchyma samples were harvested and RNAseq analysis was performed. There were 0, 49 and 1,346 genes differentially expressed in the arcuate nucleus, anterior pituitary and testicular tissue of bull calves on the low relative to the high plane of nutrition, respectively (P < 0.05; False Discovery Rate <0.05). Cell cycle processes in the anterior pituitary were down regulated in the low relative to the high plane of nutrition; there was no differential expression of genes related to reproductive processes. Gene expression involved in cholesterol and androgen biosynthesis in the testes were down regulated in animals on the low plane of nutrition. This study provides insight into the effect of early life plane of nutrition on the regulation of the HPT axis.
... This finding is based on the directional expression of the 26 DE genes involved (Fig 2), which indicates that adipose tissue of calves under an enhanced nutrient supply are processing fatty acids at a higher rate compared to restricted animals. Another study with similar treatments reported that the gene network 'energy production, lipid metabolism and small molecule biochemistry network' was enriched in subcutaneous adipose tissue of calves (126 day old) fed an enhanced diet [33]. Older animals (197-day-old Angus steers) under an enhanced nutrient supply (high concentrate diet vs. pasture) also dis- played altered transcriptome expression in subcutaneous adipose tissue (1113 DE genes), indi- cating increased lipid metabolism functions, including Fatty Acid Metabolism [34]. ...
... These findings are evidence that early life nutrient supply influences the genetic regulation of hyperplastic and hypertrophic processes in calves' adipose tissue. Our findings are supported by another study investigating low vs. high plane of nutrition in calves' subcuta- neous adipose tissue histology and transcriptome [33]. Histology results indicated that at 126 days of age, calves in a low plane of nutrition displayed less adiposity (lower quantity of adipo- cytes, smaller adipocyte diameter and more preadipocytes) when compared to calves in a high plane of nutrition [33]. ...
... Our findings are supported by another study investigating low vs. high plane of nutrition in calves' subcuta- neous adipose tissue histology and transcriptome [33]. Histology results indicated that at 126 days of age, calves in a low plane of nutrition displayed less adiposity (lower quantity of adipo- cytes, smaller adipocyte diameter and more preadipocytes) when compared to calves in a high plane of nutrition [33]. ...
Performance of dairy cows can be influenced by early life nutrient supply. Adipose tissue is diet sensitive and an important component in that process as it is involved in the regulation of energetic, reproductive and immunological functions. However, it is not clear how early life nutrition alters the molecular regulation of adipose tissue in calves and potentially adult individuals. This study aimed at determining how differences in pre-weaning nutrient supply alter gene expression profiles and physiology in omental adipose tissue. A total of 12 female Holstein calves were fed two levels of milk replacer supply: a restricted amount of 11.72 MJ of metabolizable energy (ME) intake per day (n = 6) or an enhanced amount of 1.26 MJ ME intake per kg of metabolic body weight (BW0.75), resulting in supply from 17.58 to 35.17 MJ ME intake per day (n = 6). All calves had ad libitum access to a commercial calf starter and water. Analysis of the transcriptome profiles at 54 ± 2 days of age revealed that a total of 396 out of 19,968 genes were differentially expressed (DE) between groups (p < 0.001, FDR < 0.1). The directional expression of DE genes through Ingenuity Pathway Analysis showed that an enhanced nutrient supply alters adipose tissue physiology of pre-weaned calves. Several biological functions were increased (Z-score > +2), including Lipid Metabolism (Fatty Acid Metabolism), Cell Cycle (Entry into Interphase, Interphase, Mitosis and Cell Cycle Progression), Cellular Assembly and Organization (Cytoskeleton Formation and Cytoplasm Development) and Molecular Transport (Transport of Carboxylic Acid). These changes were potentially orchestrated by the activation/inhibition of 17 upstream regulators genes. Our findings indicate that adipose tissue of calves under an enhanced nutrient supply is physiologically distinct from restricted calves due to an increased development/expansion rate and also a higher metabolic activity through increased fatty acid metabolism.
Early life nutrition has a major influence on subsequent lifetime performance in cattle. The aim of this experiment was to investigate the effect of plane of nutrition from 3 to 21 weeks of age on the liver transcriptome. Holstein-Friesian × Angus heifer calves with a mean (±SD) age and BW of 19 (±5) days and 51.2 (±7.8) kg, respectively, were assigned to either a high-energy diet to support a mean average daily gain (ADG) of 1.2 kg/day (HI; n = 15) or a moderate diet (MOD; n = 15) to support a mean ADG of 0.5 kg/day. At 145 ± 3 days of age, all calves were euthanised, liver tissue samples collected and flash-frozen in liquid nitrogen. Following RNA sequence analysis, the total number of differentially expressed genes (DEGs) (at false discovery rate (FDR) > 0.05) was 537; 308 upregulated and 229 downregulated in HI compared to MOD. The number of DEGs mapped to IPA (at FDR > 0.05) was 460; 264 upregulated and 196 downregulated. There was greater expression of genes associated with cellular development and metabolism in heifers on the HI compared to the MOD diet. The genes (fold change) of the somatotrophic axis; IGF1 (3.7), IGFALS (2.6) and GHR (1.5) were upregulated in the HI compared to MOD diet. The cytokine receptor genes, IL17RB (1.7) and IL20RA (3.3), were upregulated in the HI heifers, which were detected in a network interacting with metabolically regulated genes. The potential enhanced cell-to-cell communication evident from DEGs would increase the calves’ ability to combat health challenges. The findings of this study indicate that enhancing the early life plane of nutrition in heifer calves results in the upregulation of genes that are associated with increased metabolic activity and thus metabolic capacity. Moreover, the interaction between metabolic and immune communication genes indicates that enhanced nutrition has the potential to improve the immune response in the liver which will play a central role in ensuring optimal lifetime performance.
Enhanced early life nutrition stimulates the functionality of the hypothalamic-pituitary–testicular (HPT) biochemical signalling axis, resulting in precocious reproductive development in bull calves. Additionally, there is evidence that peptides and hormones produced within adipose tissue depots are also central in mediating the effect of metabolic status with reproductive development. The objective of this study was to undertake gene co-expression analyses on transcriptional data of the HPT and adipose tissues derived from bull calves fed contrasting planes of nutrition up to 18 weeks of life. The relationship between networks of co-expressed genes in each tissue dataset with calf phenotypic data was also assessed using a Pearson correlation analysis. Phenotypic data were related to metabolic status (systemic concentrations of insulin, leptin, adiponectin and IGF-1) reproductive development (systemic concentrations of testosterone, FSH and LH) and markers of testicular development (seminiferous tubule diameter, seminiferous tubule lumen score, spermatogenic cells and Sertoli cells). In the hypothalamus, gene co-expression networks involved in biochemical signalling processes related to gonadotropin-releasing hormone (GnRH) secretion were positively associated (P
