Project description:A transcriptomic approach was used to evaluate potential interactions between prepartum body condition score (BCS) and feeding management in the weeks before calving on hepatic metabolism during the transition period. Thirty-two mid-lactation grazing dairy cows of mixed age and breed were randomly allocated to one of four treatment groups in a 2 × 2 factorial arrangement: two prepartum BCS categories [4.0 (thin, BCS4) and 5.0 (optimal, BCS5); based on a 10-point scale], and two levels of energy intake during the 3 wk preceding calving (75 and 125% of estimated requirements). Liver samples were obtained at -7, 7, and 28 d relative to parturition and subsequent RNA was hybridized to the Agilent 44K Bovine (V2) Microarray chip. The Dynamic Impact Approach was used for pathway analysis, and Ingenuity Pathway Analysis was used for gene network analysis. The greater number of differentially expressed genes in BCS4 cows in response to prepartum feed allowance indicated that these animals were more responsive to prepartum nutrition management than optimally-conditioned cows. However, independent of prepartum BCS, pathway analysis revealed that prepartal feeding level had a marked effect on carbohydrate, amino acid, lipid, and glycan metabolism. Altered carbohydrate and amino acid metabolism indicated a greater and more prolonged negative energy balance post-calving in BCS5 cows overfed prepartum. This was indicated by opposite effects of pre-calving feeding in in BCS4 compared with BCS5 cows in amino acid, vitamin, and co-factor metabolism. The prepartum feed restriction ameliorated the metabolic adaptation to the new lactation in BCS5 cows, while detrimentally affecting BCS4 cows, which seemed to adapt better when overfed. Moreover, alterations in the glycosaminoglycans synthesis pathway support this idea, indicating better hepatic health status in feed-restricted BCS5 cows and overfed BCS4 animals. IPA network analysis indicated liver damage in feed-restricted thin cows, likely due to metabolic overload. Overall, the data indicate that overfeeding in late-pregnancy should be limited to underconditioned animals, while cow with optimal degree of body condition should be maintained on an energy restricted diet.

Project description:We evaluated if a higher plane of maternal nutrition during late gestation and weaning age alters the offspringM-bM-^@M-^Ys Longissimus muscle (LM) transcriptome. A microarray analysis was performed in LM samples of early (EW) and normal weaned (NW) Angus M-CM-^W Simmental calves born from cows that were grazing endophyte-infected tall fescue/red clover pastures with no supplement (low plane of nutrition (LPN)), or supplemented with 2.3 kg of dried distillerM-bM-^@M-^Ys grains with solubles and soyhulls (70% DDGS/30% soyhulls) (medium plane of nutrition (MPN)) during the last 90 days of gestation. Biopsies were harvested at 78, 187 and 354 days of age. Bioinformatics analysis highlighted that offspring transcriptome did not respond markedly to cow plane of nutrition, resulting in only 13 differentially expressed genes. However, weaning age and a high-starch diet strongly impacted the transcriptome, especially the immediate activation of the lipogenic program in EW steers. In addition, between 78 and 187 days of age, these animals had an activation of the innate immune system due presumably to macrophage infiltration in intramuscular fat. Between 187 and 354 days of age (i.e. the fattening phase), NW steers had an activation of the lipogenic transcriptome machinery, while EW steers had a clear gene transcription inhibition. The latter appears to have occurred through the epigenetic control of histone acetylases, which were down-regulated. Higher cow plane of nutrition alone affected 35 genes in the LM of steers that underscore the presence of a mechanism of macrophage infiltration likely originating from localized oxidative stress as a result of increased levels of hypoplasia and hypertrophy in LM. A subset of 20 Angus x Simmental beef cows from the University of Illinois Dixon Springs Agriculture Center (DSAC) in Simpson, IL, were selected from a group of animals utilized in a parallel study75. Main effects evaluated were maternal plane of nutrition during late gestation and postnatal management of the offspring. Three months prior to the projected parturition date cows were assigned to treatments (low or medium plane of nutrition) in a split-plot design. Low plane of nutrition (LPN) was achieved by grazing endophyte-infected tall fescue/red clover pastures during July, August, and September with no supplement. Medium plane of nutrition cow diet (MPN) was achieved by grazing endophyte-infected tall fescue/red clover pastures supplemented with 2.3 kg of dried distillerM-bM-^@M-^Ys grains with solubles and soyhulls (70% DDGS/30% soyhulls). Angus x Simmental steer calves were randomly assigned to early or normal weaning treatments within each gestational treatment. This allowed for 10 animals for each postnatal treatment and 5 animals of each of the interactions of gestational M-CM-^W postnatal treatments. At 78 M-BM-1 2 days postpartum, early-wean offspring were weaned, transported to Urbana Beef Unit, and adapted to a high-starch diet until they had ad libitum consumption. At 187 M-BM-1 2 days postpartum, normal-wean offspring were weaned and transported to Urbana Beef Unit. All offspring were co-mingled among treatments. LM biopsies were sampled from a subset of 5 animals per gestational M-CM-^W postnatal treatment at time of early weaning (~78 days) and at time of normal weaning (~187 days), and during the last week prior to harvest (~ 354 days). After normal weaning, all offspring were placed on a common, corn grain-based high-starch finishing diet that is typical of industry management (CP% = 18.1, NDF% = 25.3, ADF% = 14.3, crude fat % = 5.1). All the offspring in the study were harvested at a commercial packing plant when they reached the selected end point target back fat thickness of 1.1 cm. Reported final body weight (BW) was calculated from hot carcass weight using a 62% dressing percentage. In the present study, we used a transcriptome-wide bovine microarray (Agilent-015354 Bovine Oligo Microarray-4x44K) that contains 21,475 unique genes and transcripts of Bos Taurus, with two probes per gene. The methods used for hybridization and scanning were according to manufacturerM-bM-^@M-^Ys protocols and Loor et al45. The microarray data were deposited in the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) database (http://www.ncbi.nlm.nih.gov/gds) with accession number GSE-XXXX. GeneSpring GX (Agilent Technologies) was used for data visualization and preliminary data mining. Subsequently, the entire microarray data set with associated statistical P-values were imported into Ingenuity Pathways Analysis M-BM-. (IPA, www.ingenuity.com) in order to examine the number of activated and inhibited differentially expressed genes (DEG). Entrez Gene IDs were used to identify individual sequences. Data from the microarray analysis were normalized for dye and microarray effects (i.e., Lowess normalization and array centering) and used for statistical analysis. The MIXED procedure of SAS (SAS Institute, Inc., Cary, NC, USA) was used for statistical analysis. Fixed effects were treatment (early weaning, normal weaning), diet (low and medium cow plane of nutrition), time (78, 187, and 354 days of age), first, second and third order interactions between diet, time and treatment, and dye (Cy3, Cy5) and random effects included steer and microarray. Raw P values were adjusted using Benjamini and HochbergM-bM-^@M-^Ys false discovery rate (FDR). Bioinformatics analysis of microarray data was performed using DIA 10 and information from the freely-available online databases Kyoto Encyclopedia of Genes and Genomes (KEGG) and Database for Annotation, Visualization, and Integrated Discovery (DAVID) v6.7 databases. A list of gene identifiers (Entrez Gene IDs) was uploaded all at once to extract and summarize functional annotations associated with groups of genes or with each individual gene. The significance value associated with biological processes and pathways is a measure of the likelihood that the distribution of DEG in these pathways and biological processes is due to chance. The significance is expressed as a P-value, which is calculated using the right-tailed Fisher's Exact Test and adjusted using FDR. Details of the DIA approach and its validation have been reported previously. The interpretation of the bioinformatics analysis was performed following the same approach as our previous study.

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