Liver transcriptomic and proteomic profiles of preweaning lambs are modified by milk replacer restriction

Abstract

Prenatal and early postnatal nutrition may promote long-term effects on both feed efficiency and health of animals. Therefore, moderated milk replacer restriction during the artificial rearing period might negatively affect feed efficiency during the postweaning phases in dairy ewes. The aim of this work was to identify differentially expressed (DE) genes by RNA sequencing and differentially accumulated proteins using MALDI-TOF mass spectrometry in the liver of artificially reared Assaf lambs to identify modified metabolic pathways as a consequence of milk replacer restriction in order to find possible solutions to correct any detrimental effect caused by this factor. Forty female Assaf lambs were used in this experiment. The animals were penned individually and assigned randomly to 1 of 2 treatments groups (n = 20 per treatment). The first group of lambs was fed ad libitum (AL), whereas the second (restricted, RES) only received approximately 62.5% of the level of intake measured in the AL group. Eight 35-d-old lambs from each group (16 lambs in total) were harvested and a piece of liver of 8 lambs (4 AL and 4 RES lambs) was excised for transcriptomic and proteomic analysis. Differential gene expression analysis identified 386 DE genes [198 of them being annotated genes in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway], with 176 downregulated and 210 upregulated in the early feed-restricted group relative to the AL group. A total of 26 spots were also differentially accumulated proteins in the liver of the 2 groups of lambs, 10 of them being down-accumulated whereas the other 16 evolved in the opposite way in the liver of RES relative to AL lambs. Collectively, both the transcriptomic and proteomic approaches revealed an upregulation of genes participating in oxidation of fatty acids in the early feed-restricted lambs. The expression of many genes involved in the degradation of several AA (e.g. alanine, valine, isoleucine, tyrosine) was also modified in the RES lambs, probably to render substrates for gluconeogenesis. Moreover, other genes involved in apoptosis, inflammation, or hepatic oxidative pathways were upregulated in these lambs. Finally, the expression of genes implicated in oxidative phosphorylation was modified in RES animals. Altogether all these modifications suggest that the partitioning and utilization of nutrients in the early feed-restricted lambs might have been modified, being partially responsible for changes during the replacement phase later in life.

The Role of Feed Restriction on DNA Methylation, Feed Efficiency, Metabolome, Biochemical Profile, and Progesterone Patterns in the Female Filial Generation (F1) Obtained From Early Feed Restricted Ewes (F0)

“…However, the hypothesis that postnatal early feed restriction of ewe lambs (F0) can promote intergenerational transmission of epigenetic marks to the offspring (F1) is also supported by the GO enrichment analysis, where GO terms, e.g., mating, response to estrogens, and immune system process ( Supplementary Table 3 ) were observed in F1-RES lambs. At this point, it is pertinent to remember that F0 dams presented upregulation of many genes involved in metabolic pathways (e.g., steroid and steroid hormone biosynthesis, primary BA biosynthesis, and bile secretion) just after the feed restriction period (Santos et al, 2019 ). Later on, during the replacement phase, animals showed long-term effects caused by early feed restriction such as altered steroid hormone biosynthesis, modified vitamin D metabolites, retarded puberty, pro-inflammatory conditions, and impaired liver function (Frutos et al, 2018a ; Santos et al, 2018a ).…”

“…Later on, during the replacement phase, animals showed long-term effects caused by early feed restriction such as altered steroid hormone biosynthesis, modified vitamin D metabolites, retarded puberty, pro-inflammatory conditions, and impaired liver function (Frutos et al, 2018a ; Santos et al, 2018a ). According to the transcriptome profile observed for these lambs (Santos et al, 2019 ), most of these effects might be explained, at least partially, by alterations in cholesterol metabolic pathways, given the fact that cholesterol is the precursor of steroid hormones (e.g., progestagens, glucocorticoids, mineralocorticoids, androgens, and estrogens) and BAs (Watanabe et al, 2004 ). Therefore, considering the results observed in this study, some of these features in F0 dams might have been transferred to the progeny (F1) by epigenetic marks, with consequences at different functions, as explained below.…”

“…All the details of F0 Assaf dams are fully described by Santos et al (2018aSantos et al ( , 2019. In brief, the replacement ewe lambs (F0) were divided into two groups, the first one being fed milk replacer (MR) ad libitum (F0-ADL) during the suckling period and the second one (F0-RES) being milk restricted (62.5% of ad libitum intake level) during the first 35 days of life.…”

Review: Importance of colostrum supply and milk feeding intensity on gastrointestinal and systemic development in calves

“…Studies on the hepatic transcriptome and proteome in lambs and metabolome in blood plasma of calves reveal marked changes with respect to protein and energy metabolism when animals receive MR ad libitum instead of in restricted amounts (Kenéz et al, 2018;Santos et al, 2019). In lambs, restricted MR feeding stimulates hepatic pathways involved in gluconeogenesis, amino acid degradation and hepatic fatty acid oxidation, which points at changes in energy utilisation to stabilise glucose homeostasis as compared to ad libitum MR-fed lambs (Santos et al, 2019). In calves, ad libitum instead of restricted MR feeding seems to increase the capacity for mitochondrial transport of fatty acids and probably affects fatty acid oxidation as well (Kenéz et al, 2018).…”

Quantitative comparative phosphoproteomic analysis of the effects of colostrum and milk feeding on liver tissue of neonatal calves

“…Proteins, as gene products, are directly related to their critical regulatory effects in various physiological processes. Many previous animal studies investigated diet-induced changes in the proteome of liver tissue (Benard et al, 2016;Santos et al, 2019). The activity and function of proteins are regulated by posttranslational modifications, of which phosphorylation is the most common form.…”