Liver transcriptomic and plasma metabolomic profiles of fattening lambs are modified by feed restriction during the suckling period1

Abstract

The increasing world population is driving demand for improved efficiency of feed resources of livestock. However, the molecular mechanisms behind various feed efficiency traits and their regulation by nutrition remain poorly understood. Here, we aimed to identify differentially expressed (DE) genes in the liver tissues of fattening Merino lambs and differences in metabolites accumulated in plasma to identify modified metabolic pathways as a consequence of milk restriction during the suckling period. Twenty-four male Merino lambs (4.81 ± 0.256 kg) were divided into 2 groups (n = 12 per dietary treatment). The first group (ad libitum, ADL) was kept permanently with the dams, whereas the other group (restricted, RES) was milk restricted. When they reached 15 kg of live body weight (LBW), all the animals were offered the same complete pelleted diet at the same level (35 g DM/kg LBW per day) to ensure no differences in dry matter intake. All the lambs were harvested when they reached 27 kg of LBW. For transcriptomic analysis, 4 liver samples from each group (8 samples in total) were selected for RNA sequencing (RNA-seq), and plasma samples from all animals (24 samples in total) were used to perform a nontargeted metabolomic analysis on a hybrid quadrupole-time-of-flight mass spectrometer coupled to an ultra-high performance liquid chromatographic system (UHPLC/QTOF-MS). Thirty-eight DE annotated genes were identified by RNA-seq, with 23 DE genes being down-regulated and 15 up-regulated in the liver of RES lambs relative to the ADL group (P < 0.10). Also, the metabolomic assay identified 38 differentially accumulated compounds (P < 0.10). In general, those genes and pathways involved in protein synthesis or protease inhibitors were down-regulated in the RES group, whereas those related to proteolytic degradation were up-regulated, thus suggesting a higher catabolism of proteins in these lambs. RES lambs showed over-expression of xenobiotic metabolism pathways, whereas those genes related to β-oxidation of fatty acids were down-regulated. According to the data obtained, early feed restriction during the suckling period of Merino lambs promoted long-term effects on both the hepatic transcriptomic profile and plasma metabolic profile, which might have modified fatty acids metabolism, catabolism of proteins, and detoxification of xenobiotics, thus reducing feed efficiency during the fattening period.

Early Feed Restriction Programs Metabolic Disorders in Fattening Merino Lambs

“…Each lamb was weaned progressively starting at 13.5 kg body weight (BW). Weaned lambs weighing 15 kg of BW were penned individually, had free access to fresh drinking water, and were offered the same complete pelleted diet (CPD) at 35 g/kg BW per day throughout the fattening period to avoid differences in dry matter intake as explained elsewhere [ 10 , 12 , 13 ]. All the lambs received the CPD as a single daily meal at 09:00 h, and the amount of feed offered was adjusted twice a week based on the BW.…”

Early feed restriction of lambs modifies ileal epimural microbiota and affects immunity parameters during the fattening period

“…One of these factors might be related to early feed restriction of animals (Greenwood and Cafe, 2007) during the postnatal phases, when the colonization of mucosal epithelium of the gastrointestinal tract by commensal bacteria takes place (Taschuk and Griebel, 2012). Interestingly, once established the epimural microbiota seems to be less influenced by the diet than microbiota associated to digesta contents (Petri et al, 2013;Yáñez-Ruiz et al, 2015), so any factor (e.g., early feed restriction) modifying the composition of the microbiota firmly attached to these cells may modulate not only the nutrient processing (Santos et al, 2018a and2018b) but also the gut-associated lymphoid tissue, thus exerting nutritional programming of immune health and hence long-term effects on lifetime feed efficiency.…”

Proceedings of the 10th International Symposium on the Nutrition of Herbivores

“…Introduction Early feed restriction during the suckling period may impact feed efficiency traits during post-weaning phases (Santos et al, 2018). In this sense, differential gene expression between individuals is a key source of variation that can be used to identify candidate genes and pathways involved in metabolic programming (Ruchat et al, 2014).…”