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Kong F, Gao Y, Tang M, Fu T, Diao Q, Bi Y, Tu Y. Effects of dietary rumen-protected Lys levels on rumen fermentation and bacterial community composition in Holstein heifers. Appl Microbiol Biotechnol 2020; 104:6623-6634. [PMID: 32519120 DOI: 10.1007/s00253-020-10684-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/06/2020] [Accepted: 05/17/2020] [Indexed: 01/05/2023]
Abstract
This study aimed to evaluate the effects of partial reducing rumen-protected Lys (RPLys) on rumen fermentation and microbial composition in heifers. Three ruminal fistulated Holstein Friesian bulls were used to determine the effective degradability of RPLys using an in situ method at incubation times of 0, 2, 6, 12, 16, 24, 36, and 48 h. Thereafter, 36 Holstein heifers at 90 days of age were assigned to one of two dietary treatments: a theoretically balanced amino acid diet (PC group; 1.21% Lys, 0.4% Met) or a 30% Lys-reduced diet (PCLys group, 0.85% Lys, 0.4% Met). Rumen fluid samples from five heifers in each group were extracted using esophageal tubing on day 90 to determine pH, microprotein, ammonia, volatile fatty acids, and microbial communities. Results showed that the effective ruminal degradability was 25.76%. Furthermore, differences in rumen fermentation parameters and alpha diversity of the microbiota between the two groups were not significant, but beta diversity was significant. Based upon relative abundance analysis, short-chain fatty acid-producing bacteria, including Sharpea, Syntrophococcus, [Ruminococcus]_gauvreauii_group, Acetitomaculum, and [Eubacterium]_nadotum_group belonging to Firmicutes, were significantly decreased in the PCLys group. Spearman's analysis revealed a positive correlation between the butyrate molar proportion and the relative abundance of butyrate-producing bacteria such as [Eubacterium]_nadotum_group, Coprococcus_1, Ruminococcaceae_UCG_013, Pseudoramibacter, and Lachnospiraceae_UCG_010. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States analysis further validated that RPLys deduction influenced energy metabolism. Together, our findings highlight the role of RPLys or Lys in butyrate-producing bacteria. However, the number of bacteria affected by Lys was very limited and insufficient to alter rumen fermentation. Key Points • Reducing 30% Lys via rumen-protected Lys did not affect rumen fermentation parameters and alpha diversity of microbiota of Holstein heifers. It meant that the ruminal fermentation pattern was not changed. • Reducing 30% Lys via rumen-protected lysine significantly decreased relative abundance of short-chain fatty acid-producing bacteria belonging to Firmicutes. • Functions of microorganisms were changed by reducing 30% Lys via rumen-protected Lys, especially amino acid metabolism. It may affect the amino acid composition of microprotein.
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Affiliation(s)
- Fanlin Kong
- Key Laboratory of Feed Biotechnology of the Ministry of Agriculture, Sino-US Joint Lab on Nutrition and Metabolism of Ruminants, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Yanxia Gao
- College of Animal Science and Technology, Hebei Agricultural University, Baoding, 071001, China
| | - Mengqi Tang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450002, China
| | - Tong Fu
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450002, China
| | - Qiyu Diao
- Key Laboratory of Feed Biotechnology of the Ministry of Agriculture, Sino-US Joint Lab on Nutrition and Metabolism of Ruminants, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Yanliang Bi
- Key Laboratory of Feed Biotechnology of the Ministry of Agriculture, Sino-US Joint Lab on Nutrition and Metabolism of Ruminants, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Yan Tu
- Key Laboratory of Feed Biotechnology of the Ministry of Agriculture, Sino-US Joint Lab on Nutrition and Metabolism of Ruminants, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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