Hepatic transcriptome perturbations in dairy cows fed different forage resources

Hepatic Global Transcriptomic Profiles of Holstein Cows According to Parity Reveal Age-Related Changes in Early Lactation

Cows can live for over 20 years, but their productive lifespan averages only around 3 years after first calving. Liver dysfunction can reduce lifespan by increasing the risk of metabolic and infectious disease. This study investigated the changes in hepatic global transcriptomic profiles in early lactation Holstein cows in different lactations. Cows from five herds were grouped as primiparous (lactation number 1, PP, 534.7 ± 6.9 kg, n = 41), or multiparous with lactation numbers 2-3 (MP2-3, 634.5 ± 7.5 kg, n = 87) or 4-7 (MP4-7, 686.6 ± 11.4 kg, n = 40). Liver biopsies were collected at around 14 days after calving for RNA sequencing. Blood metabolites and milk yields were measured, and energy balance was calculated. There were extensive differences in hepatic gene expression between MP and PP cows, with 568 differentially expressed genes (DEGs) between MP2-3 and PP cows, and 719 DEGs between MP4-7 and PP cows, with downregulated DEGs predominating in MP cows. The differences between the two age groups of MP cows were moderate (82 DEGs). The gene expression differences suggested that MP cows had reduced immune functions compared with the PP cows. MP cows had increased gluconeogenesis but also evidence of impaired liver functionality. The MP cows had dysregulated protein synthesis and glycerophospholipid metabolism, and impaired genome and RNA stability and nutrient transport (22 differentially expressed solute carrier transporters). The genes associated with cell cycle arrest, apoptosis, and the production of antimicrobial peptides were upregulated. More surprisingly, evidence of hepatic inflammation leading to fibrosis was present in the primiparous cows as they started their first lactation. This study has therefore shown that the ageing process in the livers of dairy cows is accelerated by successive lactations and increasing milk yields. This was associated with evidence of metabolic and immune disorders together with hepatic dysfunction. These problems are likely to increase involuntary culling, thus reducing the average longevity in dairy herds.

Efficacy of hepatoprotectors in prophylaxis of hepatosis of laying hens

Hepatoses of laying hens are quite common in poultry farms as a result of improper practices of poultry maintenance consisting in excessive number of protein feeds for provision of high productivity. The objective of the study was preventive efficacy of Gep-A-Stress hepatoprotectors (carnitine hydrochloride, D L methionine, sorbitol, choline chloride, magnesium sulfate heptahydrate) and Hepasan VS (L-carnitine hydrochloride, sorbitol, choline chloride, magnesium sulfate hepahydrate, betaine hydrochloride, L-arginin) against hepatosis of laying hens. To determine the efficacy of Hep-A-Stres and Hepasan-VS hepatoprotectors during production tests (n = 4,500), we monitored the parameters of survival rate (the final number of individuals as percentage of the initial number) and egg productivity of laying hens. We determined that after 30 days of using the hepatoprotectors, the content of overall protein in blood serum of laying hens of the first and the second experimental groups decreased by 21.4% and 18.9% compared with the parameters prior to providing the hepatoprotectors and by 26.3% and 23.3% compared with the control group after receiving the drug. The urea contents in blood serum increased by 19.0% and 10.5%. Compared with the control, the activity of alanine aminotransferase decreased by 43.7% and 24.1% in the first experimental group and by 23.4% and 14.9% in the second. The activity of aspartate aminotransferase in blood serum of the experimental groups decreased by 10.7%. The cholesterol concentration decreased by 50% and 58.3%. The content of triaglycerols decreased by 24.1% and 8.9% respectively. The concentrations of high-density lipoproteins after 30 days of the experiment decreased by 33.3% and 77.8% respectively, the content of low-density lipoproteins decreased by 61.3% and 40.4% and 42.3%. Population maintenance equaled respectively 97.1%, 98.3% and 98.1%. At the end of the experiment, the egg productivity of laying hens of the first and second groups increased by 4% and 3.6% compared with the control. Therefore, intake of the hepaprotectors by laying hens stimulated their metabolism, positively influenced the blood parameters, survival and egg productivity. The conducted studies confirm the benefits of using hepatoprotectors for the prohylaxis of hepatosis of hens.

Effects of Heat Stress on the Ruminal Epithelial Barrier of Dairy Cows Revealed by Micromorphological Observation and Transcriptomic Analysis

Heat stress (HS) alters the rumen fermentation of dairy cows thereby affecting the metabolism of rumen papillae and thus the epithelial barrier function. The aim of the present study was to investigate if HS damages the barrier function of ruminal epithelia. Eight multiparous Holstein dairy cows with rumen cannula were randomly equally allocated to two replicates (n = 4), with each replicate being subjected to heat stress or thermal neutrality and pair-feeding in four environmental chambers. Micromorphological observation showed HS aggravated the shedding of the corneum and destroyed the physical barrier of the ruminal epithelium to a certain extent. Transcriptomics analysis of the rumen papillae revealed pathways associated with DNA replication and repair and amino acid metabolism were perturbated, the biological processes including sister chromatid segregation, etc. were up-regulated by HS, while the MAPK and NF-kB cell signaling pathways were downregulated. However, no heat stress-specific change in the expression of tight junction protein or TLR4 signaling was found, suggesting that HS negatively affected the physical barrier of the ruminal epithelium to some extent but did not break the ruminal epithelium. Heat stress invoked mechanisms to maintain the integrity of the rumen epithelial barrier by upregulating the expression of heat shock protein and repairments in rumen papillae. The increase in amino acid metabolism in rumen papillae might affect the nutrient utilization of the whole body. The findings of this study may inform future research to better understand how heat stress affects the physiology and productivity of lactating cows and the development of mitigation strategies.