Rumen bacterial diversity and efficiency of nitrogen use in Nellore steers fed with different levels and sources of protein in the diet

Author(s)

Kênia Larissa Gomes Carvalho Alves

• Document type: Master's Dissertation
• Press: Jaboticabal. 2019-04-30.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2019-03-01
• Advisor: Telma Teresinha Berchielli

Abstract

The objective of this study was to characterize the ruminal bacterial community in Nellore steers fed different levels and protein sources in high concentrate diets and to identify possible associations between the ruminal microbial profile and the variations in the efficiency of animal nitrogen utilization. Six Nellore steers were used, cannulated in the rumen and duodenum, distributed in a model of incomplete blocks, with six diets and four experimental periods. The soybean meal + urea (FS), corn gluten 60 (GLU) and dry grains were obtained by distillation from the sugar cane and the concentrates had two inclusion levels of crude protein 10 and 13% and three protein sources: of corn processing (DDG). The DDG protein source was significant in the evaluation of diversity indexes Shannon Wiener and Simpson (P <0.010). The richness was evaluated by the Chao1 index and the results showed a richer ruminal environment with 10% content (P <0.010) and FS source (P <0.010). Animals fed with 13% CP showed greater abundance of Elusimicrobia and Spirochaetes (P> 0.01) and lower abundance of Bacteriodetes and Synergistetes (P> 0.01). Nitrogen retention was not influenced by the content and the source used, so the nitrogen retention data were distributed in three clusters: high, medium and low using the NbClust package version 2.0. The low N retention was associated with Prevotella (P = 0.029), Weissella (P = 0.024), and Mogibacterium (P = .089) and Eubacterium. (P = 0.043). When we correlated N balance data with the microbial profile, the genera Butyruvibrio (r = -0.434 P = 0.034), Hespelia (r = - 0.060 P = 0.002) and Coprococcus (r = -0.404 P = 0.050) correlated negatively with the retention of N. Urinary excretion of N correlated positively with the genus Lactonifactor (r = 0.545 P = 0.06) and Lachonospiraceae (R = 0.721 and 0.007). Microorganisms that negatively correlated with this same variable were Elusimicrobia (r = -0.415 P = 0.044), Victivallis (r = -0.486 P = 0.016). Protein contents and sources alter ruminal microbial diversity, but did not influence N retention. Microorganisms that are associated with N fixation, amino acid production and correlate with N excretion via urine were associated with high retention of N. On the other hand, microorganisms with low proteolytic activity, ammonia hyperproducers were associated with low N retention. (AU)

• FAPESP's process: 17/11571-0 - Rumen bacterial diversity and efficiency of nitrogen use in Nellore steers fed with different levels and sources of protein in the diet
• Grantee: Kênia Larissa Gomes Carvalho Alves
• Support Opportunities: Scholarships in Brazil - Master