Transcriptome Analysis and Expression of Selected Cationic Amino Acid Transporters in the Liver of Broiler Chicken Fed Diets with Varying Concentrations of Lysine

Identification of genes related to growth and amino acid metabolism from the transcriptome profile of the liver of growing laying hens

The growing period is a critical period for the growth and development of hens and affects their production performance during the laying period. During the early stage of growing, bone and muscle growth is rapid, making it necessary to provide sufficient amino acids (AA) to support the growth and development of laying hens. In this experiment, RNA-Sequencing (RNA-Seq) was applied to compare the liver tissues from 6- to 12-wk-old growing laying hens to identify candidate genes related to growth and AA transport and metabolism. In the liver tissues, 596 differentially expressed genes (DEG) were identified, of which 424 genes were up-regulated and 172 were down-regulated. Through enrichment analysis and DEGs analysis, some DEGs and pathways related to AA transport and metabolism were identified. Additionally, there were significantly increased activities in the liver of glutamate dehydrogenase (GDH), glutamic oxaloacetic transaminase (GOT), and glutamate pyruvate transaminase (GPT). Meanwhile, the level of serum insulin-like growth factor binding protein-5 (IGFBP-5) significantly elevated, and insulin-like growth factor-1 (IGF-1) levels significantly reduced at 12 wk compared to 6 wk. The AA contents in the breast muscle were not significantly altered, while the levels of the free AA in the serum underwent significant changes. This study discovered that the transport and metabolism of AAs in growing laying hens at different ages changed, which influenced the growth and development of growing laying hens. This contributes to future research on the mechanisms of growth and AA metabolism during the growing period of laying hens.

The Interaction between Feed Bioactive Compounds and Chicken Genome

Consumer demand for high quality and safe foods that will have a positive impact on their health has increased in recent years. Today, it is possible to meet those demands by combining the genetic potential of domestic animals and applying different feeding strategies. Nutrigenomics is one of the "omics" sciences that studies the interaction between nutrients and the genome together with their influence on metabolic and physiological processes in the body. While nutrition of domestic animals is solely based on studying the influence of nutrients on animal health and production traits, nutrigenomics integrates the fields of nutrition, genomics, molecular genetics and bioinformatics. By understanding the molecular relationships between different forms and/or concentrations of nutrients in feed and genes, it is possible to answer the question of how small changes in the diet of farm animals can produce a quality product with positive effects on human health. The aim of this article is to describe how the manipulation of adding different nutrients in the feed affects the expression of different genes in chicken and consequently alters their phenotype.

Impacts of Dietary Lysine and Crude Protein on Performance, Hepatic and Renal Functions, Biochemical Parameters, and Histomorphology of Small Intestine, Liver, and Kidney in Broiler Chickens

The present study aimed to investigate the effects of increasing dietary lysine (Lys) levels with an adequate dietary crude protein (CP) content, as well as the effects of a reduction in dietary CP content with the recommended amino acid (AAs) level, on the performance, blood biochemical parameters, and histomorphology of the duodenum, liver, and kidney in broiler chickens. A total of 500 broiler chickens were randomly distributed into five dietary treatment groups, following a completely randomized design, where, at the beginning, the control group (C) was fed a diet containing the standard CP and Lys levels: 23% CP with 1.44% Lys during the starter period; 21.5% CP with 1.29% Lys during the growing period; and 19.5% CP with 1.16% Lys during the finishing period. The Lys content was increased by 10% above the recommended control basal requirements in the second group (Gr1) and by 20% in the third group (Gr2), while using the same recommended CP percentage as the C group. The fourth group (Gr3) had a 1% lower CP content and the fifth group had a 2% lower CP content than the C group, with the same recommended AA level as the C group. Increasing the Lys content in the Gr1 group improved the broilers' weight gains (p < 0.05) during the starter, growing, and finishing periods. Decreasing dietary CP with the standard AA levels (Gr3 and Gr4) did not significantly affect (p > 0.05) the live weight gain, feed intake, or feed conversion ratio (FCR) of the broilers compared with those fed with the C diet. Blood total bilirubin, direct and indirect bilirubin, triglycerides, cholesterol, low-density lipoprotein (LDL), and very LDL were not different among the experimental groups. However, blood aspartate aminotransferase levels were increased (p < 0.05) in the Gr1 and Gr3 groups compared with the other treatment groups. All dietary treatments decreased the serum creatinine levels (p < 0.05) compared with the C group. The Gr2 broilers had greater serum total protein and globulin (p < 0.05) than those receiving the other treatments. Increasing dietary Lys levels resulted in a significant improvement in duodenum villus height and width (p < 0.05), while the low-CP diets resulted in shorter villi length and width, along with degenerated areas and lymphocytic infiltration. Low dietary CP content induced hepatocyte disorganization and moderate degeneration, along with vacuolated hepatic cells, excessive connective tissue, and lymphocytic infiltration. The cortical regions of the kidney exhibited obvious alterations in the Gr3 and Gr4 groups and large interstitial spaces were found between tubules. Renal tubules in the Gr3 and Gr4 groups were smaller in size and some of these tubules were atrophied. In conclusion, reducing dietary CP levels to 1% or 2% lower than the recommended level did not negatively affect growth performance, inducing minimal influence on the blood metabolic indicators of health status, and resulting in moderate alterations to the histomorphology of the duodenum, liver, and kidney. Furthermore, increasing the Lys content by 10% above the recommended level improved the growth performance, health status, and histomorphology of the duodenum, liver, and kidney in broiler chickens.

Analysis of performance, bone characteristics, and expression of genes involved in the balance of ionic concentrations in broilers subjected to dietary electrolyte balance levels

1. Sodium bicarbonate (NaHCO₃), potassium carbonate (K₂CO₃), and ammonium chloride (NH₄Cl) are commonly used to correct dietary electrolyte balance (DEB) in birds. However, there are many gaps in the knowledge of their effects when used simultaneously. This study investigated the effect of DEB levels on performance, femur bone characteristics and the expression of genes related to the balance of ionic concentrations in broilers at 21 days of age.2. Male Cobb broiler chickens (n = 245), aged 1-21 d, were divided into groups based on a completely randomised design with five DEB levels (110 mEq/kg, 175 mEq/kg, 240 mEq/kg, 305 mEq/kg, and 370 mEq/kg).3. The performance characteristics measured included body weight (BW), body weight gain (BWG), feed intake (FI), feed conversion (FCR) and body weight birds slaughtered (BWS).4. The bone variables assessed in the femur were weight (WE), relative bone weight (RBWE), length (L), width (WI), maximum load supported (MLS), bone-breaking resistance (BR), and Seedor index (SI). In addition, the expression of CHP1, SLC9A1, and SLC24A3 in the livers, intestines and kidneys of birds was evaluated.5. The DEB level of 370 mEq/kg, at Na⁺ content of 0.48%, resulted in the highest averages for L, MLS, and BR of the femur. This DEB level increased the expression of SLC9A1 in the liver and SLC24A3 in the intestine. A 240 mEq/kg DEB level decreased the expression of CHP1 in the liver, while supplementation with 110 mEq/kg increased the expression of SLC24A3 in the kidney.6. In conclusion, 370 mEq/kg DEB improved FCR and increased the mean bone characteristics of the femur (L, MLS, and BR) and the expression of SLC9A1 and SLC24A3 in the liver and intestine, respectively. These findings should be considered in future assessments of the effects of DEB levels on broilers.