Effects of milk replacer meal size on feed intake, growth performance, and blood metabolites and hormones of calves fed milk replacer with or without butyrate ad libitum: A cluster-analytic approach.

This study intended to classify ad libitum-fed calves according to their milk replacer (MR) meal size using the K-means clustering approach. This study aimed to investigate the effects of MR meal size on feed intake, growth performance, and blood metabolic and hormones of ad libitum MR-fed calves. German Holstein calves (16 male and 16 female) were studied from birth until d 77 of age. All calves received first colostrum (2.5 kg) milked from their dams within 2 h after birth. Subsequent colostrum meals (subsequent 4 meals until 2.5 d of age; 2 meals/d) and MR (125 g of powder/L; 21.7% crude protein, 18.6% crude fat) were fed ad libitum by teat bucket until d 10 ± 2 of age. Afterward, calves were housed in group pens with automatic feeders for MR (maximum of 25 L/d) and concentrate from 10 ± 3 d of age. Half of the calves received MR supplemented with butyrate to improve growth performance. Milk intake was stepped down to 2 L/d from wk 9 to 10, and 2 L/d of MR were offered until the end of the study. On d 1, 2, 4, and 7, and then weekly until wk 11 of age, blood samples were collected for measurement of metabolites and hormones related to energy metabolism and growth. The K-means cluster analysis on the MR meal size data collected from the automatic feeder resulted in 3 clusters (n = 14, n = 12, and n = 6). Two clusters with a sufficient cluster size (n = 14 and n = 12) were included for further statistical analysis using repeated measures mixed-model ANOVA. In both clusters, butyrate supplementation was equally distributed and failed to affect a difference in MR meal size. Cluster 1 showed calves with higher MR meal size (HI; 2.2 ± 0.11 L/visit of MR) and cluster 2 with lower meal size (LO; 1.8 ± 0.07 L/visit of MR) supplemented MR without (HIB-; n = 6; LOB-, n = 7) or with 0.33% calcium-sodium butyrate (HIB+; n = 6; LOB+, n = 7). Dry matter intake of MR did not differ between HI and LO, but intakes of concentrate and total dry matter tended to be greater in HI than in LO and increased more distinctly in HI than in LO at the end of the study. The average daily gain (g/d) was greater in HI than in LO. Plasma concentrations of total protein (g/L), albumin (g/L), glucose (mmol/L), urea (mmol/L), insulin (µg/L), and glucagon (ng/L) were higher, and the concentrations of insulin-like growth factor I tended to be higher, in HI than in LO calves. Plasma ß-hydroxybutyrate was higher in LO than in HI at d 63 and lower in calves fed MR with butyrate at d 77. In conclusion, clustering analysis discriminates 2 main groups of calves with different MR meal size and indicates an effect of MR meal size on solid feed intake, growth performance, and metabolic changes.

Long noncoding RNAs are associated with metabolic and cellular processes in the jejunum mucosa of pre-weaning calves in response to different diets.

Long noncoding RNAs (lncRNAs) emerged as important regulatory component of mechanisms involved in gene expression, chromatin modification and epigenetic processes, but they are rarely annotated in the bovine genome. Our study monitored the jejunum transcriptome of German Holstein calves fed two different milk diets using transcriptome sequencing (RNA-seq). To identify potential lncRNAs within the pool of unknown transcripts, four bioinformatic lncRNA prediction tools were applied. The intersection of the alignment-free lncRNA prediction tools (CNCI, PLEK and FEELnc) predicted 1,812 lncRNA transcripts concordantly comprising a catalogue of 1,042 putative lncRNA loci expressed in the calves' intestinal mucosa. Nine lncRNA loci were differentially expressed (DE lncRNAs) between both calf groups. To elucidate their biological function, we applied a systems biology approach that combines weighted gene co-expression network analysis with functional enrichment and biological pathway analysis. Four DE lncRNAs were found to be strongly correlated with a gene network module (GNM) enriched for genes from canonical pathways of remodeling of epithelial adherens junction, tight junction and integrin signaling. Another DE lncRNA was strongly correlated with a GNM enriched for genes associated with energy metabolism and maintaining of cellular homeostasis with a focus on mitochondrial processes. Our data suggest that these DE lncRNAs may play potential regulatory roles in modulating biological processes associated with energy metabolism pathways and cellular signaling processes affecting the barrier function of intestinal epithelial cells of calves in response to different feeding regimens in the pre-weaning period.