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| Author(s): |
Yury Tatiana Granja Salcedo
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Jaboticabal. 2017-04-06. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal |
| Defense date: | 2017-02-21 |
| Advisor: | Telma Teresinha Berchielli; Juliana Duarte Messana |
| Abstract | |
The objective of this study was to investigate three methods and four storage times for rumen sampling in terms of quality and yield of extracted metagenomic DNA as well as the composition of the rumen bacterial community, and evaluate the effect of soybean oil (SO) and crude glycerin (CG) association on ruminal fermentation, ruminal biohydrogenation (BH) and ruminal microbial population in Nellore steers. In the experiment 1: One Nellore steer fitted with a ruminal silicone-type cannula was used as a donor of ruminal contents. The experiment comprised 11 experimental groups: pellet control (PC), lyophilized control (LC), P-20: pellet stored frozen at -20 °C for a period of 3, 6, and 12 months, P-80: pellet stored frozen at -80 °C for a period of 3, 6, and 12 months, and L-20: lyophilized sample stored frozen at -20 °C for a period of 3, 6, and 12 months. The L-20 method could not maintain the yield of DNA during storage. In addition, the P-80 group showed a greater yield of metagenomic DNA than the other groups after 6 months of storage. Rumen samples stored as pellets (P-20 and P-80) resulted in lower richness Chao 1, ACE, and Shannon Wiener indices when compared to PC, while LC and PC were only different in richness ACE. The storage method and storage time influenced the proportions of 14 of 17 phyla identified by sequencing. In the P-20 group, the proportion of Cyanobacteria, Elusimicrobia, Fibrobacteres, Lentisphaerae, Proteobacteria, and Spirochaetes phyla identified was lower than 1%. In the P-80 group, there was an increase in the proportion of the Bacteroidetes phylum (p = 0.010); however, the proportion of Actinobacteria, Chloroflexi, SR1, Synergistetes, TM7, and WPS.2 phyla were unchanged compared to the PC group (p > 0.05). The class Clostridium was the most abundant in all stored groups and increased in its proportion, especially in the L-20 group. The rumen sample storage time significantly reduced the yield of metagenomic DNA extracted. Therefore, the storage method can influence the abundance of phyla, classes, and bacterial families studied in rumen samples and affect the richness and diversity index. In the experiment 2: Eight Nellore castrated and fitted with ruminal and duodenal cannulas were used in a double, simultaneous, Latin square design 4 × 4 with a 2 × 2 factorial arrangement of treatments (with or without SO and with or without CG). Steers fed with SO without CG showed lowest intake of DM, CP and NFC and presented lowest DM and NDF digestibility. A higher duodenal flow of monounsaturated fatty acid (MUFA), poly-unsaturated fatty acid (PUFA) and unsaturated fatty acid (UFA) was observed with the CG and SO association diet. There was an interaction between CG and SO on the ruminal BH rate of PUFA, UFA, and linolenic acid, the BH being lower with the CG and SO association diet than with the SO without CG diet. This interaction was also observed to affect the BH rate of MUFA, which was lower with the CG and SO association diet. Steers fed with oil and glycerine association diet had highest rumen pH and lowest ruminal N-NH3 concentration. Diets with CG addition reduced the acetate: propionate ratio and increased the proportion of iso-butirate, butirate, iso-valerate and valerate. Steers fed with both diets contain SO had lower total N excretion and showed higher N retained expressed as % N intake. SO and CG association diet generated higher rumen abundance of Prevotella, Succinivibrio, Ruminococcus, Syntrophococcus and Succiniclasticum. Rumen Archaea abundance and total ciliate protozoa were lower in steers fed with diets contained SO. The SO without CG diet reduced the population of Ruminococcus flavefaciens, R. albus and Fibrobacter succinogenes. CG associated with SO could be used as an energy source, and is a useful partial replacement for corn in cattle diets, resulting in a reduction of the total nitrogen excretion and ruminal methanogen abundance. This is environmentally beneficial, since methane emissions could be reduced without affecting dietary intake and digestibility, even when high lipid content is added to the diet. In addition, this association in the diet limited the BH of UFA, and increased the duodenal flow of these acids without influencing the cellulolytic bacteria of the rumen; therefore, this association may be a nutritional strategy to increase the deposition of healthy UFA in meat. (AU) | |
| FAPESP's process: | 13/23851-6 - DNA extraction methods for the study of rumen microbial population in cattle fed with glycerin associated with oil |
| Grantee: | Yury Tatiana Granja Salcedo |
| Support Opportunities: | Scholarships in Brazil - Doctorate |