The crucial role of lysine in the hepatic metabolism of growing Holstein dairy heifers as revealed by LC-MS-based untargeted metabolomics

Abstract

The objective of this experiment was to evaluate the effect of supplementing rumen-protected Lys based on a Lys-deficient diet on liver metabolism in growing Holstein heifers. The experiment was conducted for 3 months with 36 Holstein heifers (initial body weight: 200 ± 9.0 kg; 7-month-old). Heifers were randomly assigned to 2 diets based on corn, soybean meal, alfalfa hay, and wheat bran: control, Lys-deficient diet (LD; 0.66% Lys in diet), and Lys-adequate diet (LA; 1.00% Lys in diet). The results showed no difference in growth performance between the 2 groups ( P > 0.05). However, there was a clear trend of increasing feed conversion rate with Lys supplementation (0.05 < P < 0.01). The serum urea nitrogen concentration was significantly decreased, and the aspartate aminotransferase-to-alanine aminotransferase ratio was significantly decreased by Lys supplementation ( P < 0.05). Moreover, growing heifers fed a Lys-adequate diet had lower levels of urine nitrogen excretion and higher levels of the biological value of nitrogen ( P < 0.05). Metabolomic analysis revealed that 5 types of phosphatidylcholine and 3 types of ceramide were significantly increased and enriched in sphingolipid metabolism and glycerophospholipid metabolism ( P < 0.05). His, Leu, and Asp levels were significantly decreased in the liver following Lys supplementation ( P < 0.05). In conclusion, Lys supplementation may promote the synthesis of body tissue proteins, as evidenced by significantly decreased amino acids in the liver and urine N excretion, it also improves hepatic lipid metabolism by providing lipoprotein precursors.

Comparison of Growth Performance, Immunity, Antioxidant Capacity, and Liver Transcriptome of Calves between Whole Milk and Plant Protein-Based Milk Replacer under the Same Energy and Protein Levels

“…The amounts of starter feed and milk or milk replacer that was remaining and the amount that was added were recorded. Moreover, the milk was sampled before the morning feeding every 15 d throughout the study period to measure its chemical composition according to the method described by Kong et al [ 24 ]. The ingredients and the chemical compositions of the milk and milk replacer, and the starter feed are shown in Table 1 and Table S1 , respectively.…”

Effect of Boiling Carica Pubescens Seeds on Antinutrient Content and in Vitro Nutrient Digestibility

“…The highest essential amino acid from Carica pubescens seeds is dominated by lysine (1.57% w/w). Lysine is necessary because it is one of the precursors to the growth of rumen microorganisms (Kong et al 2021). Lysine has a part in forming carnitine, which can stimulate growth, guard against ammonia toxicity, and improve the body's ability to fend off extreme temperature fluctuations (Aristasari et al 2018).…”