Relationship between true digestibility of dietary phosphorus and gastrointestinal bacteria of goats

The present research was conducted to evaluate the connection between the true digestibility of Phosphorus (TDP) in diet and bacterial community structure in the gastrointestinal tract (GIT) of goats. Twenty-eight Nubian goats were chosen and metabolic experiment was conducted to analyze TDP of research animals. Eight goats were grouped into the high digestibility of phosphorus (HP) phenotype, and another 8 were grouped into the low digestibility of phosphorus (LP) phenotype. And from the rumen, abomasum, jejunim, cecum and colon content of the goats, bacterial 16S rRNA gene amplicons were sequenced. In the rumen 239 genera belonging to 23 phyla, in abomasum 319 genera belonging to 30 phyla, in jejunum 248 genera belonging to 36 phyla, in colon 248 genera belonging to 25 phyla and in cecum 246 genera belonging to 23 phyla were noticed. In addition, there was a significant correlation between the TDP and the abundance of Ruminococcaceae_UCG-010, Ruminococcus_2, Ruminococcaceae_UCG-014, Selenomonas_1 and Prevotella in the rumen, Lachnospiraceae_ND3007_group, Saccharofermentans, Ruminococcus_1, Ruminococcaceae_UCG-014, Lachnospiraceae_XPB1014_group and Desulfovibrio in the abomasum, Prevotella, Clostridium_sensu_stricto_1, Fibrobacter, Desulfovibrio and Ruminococcus_2 in the jejunum, Ruminococcaceae_UCG-014 in the colon, and Desulfovibrio in the cecum. Present research trial recommended that the community of gastrointestinal microbiota is a factor affecting TDP in goats.


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Phosphorus is a major mineral element that affects the growth and development of animals 43 and acts a vital biological part in the formation and growth of skeletons. Young animals develop 44 rickets, and adult animals present osteomalacia when animals lack phosphorus. In addition, 45 phosphorus also participates in the digestion and metabolism of almost all nutrients, such as 46 amino acids, lipids and carbohydrates, in animals in the form of nucleic acids, phosphoproteins 47 and phospholipids [1]. It was found that phosphorus in plant feedstuff is poorly or not at all 48 utilized by monogastric animals due to phytic acid (myo-inositol hexaphosphoric acid) binding. 49 The undigested phytate phosphorus is excreted with feces, which causes severe environmental 50 pollution problems, paying to surface water eutrophication in parts where the livestock 51 production of monogastric is intensive [2,3] . Phytase is a type of phosphatase enzyme that 52 catalyzes the hydrolysis of phytic acid found in grains and oil seeds to myo-inositol and To date, many microorganisms secreting phytase have been identified in the rumen of 60 ruminants, and some strains have been isolated and cultured in vitro for industrial production of 61 phytase [8,9]. Though, there are still many defects in the production and application of phytase,   During the metabolism trial period all the urine and feces were collected, for nitrogen fixation 99 the 10% random samples were collected each day and then mixed with 10ml of hydrochloride 100 10%. For nutritional composition measurement, daily feed intake and residual were recorded 101 during the 6-days metabolism trial period and TDP was also measured on same duration.

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Prior to morning feeding on the second day after the second metabolism experiment, the 103 blood samples were collected from each goat. Then the goats were slaughtered and the GIT 104 organs (rumen, abomasum, jeujinu, cecum and colon) were unglued to collect rumen (8 tubes, 105 each 50 mL), abomasums (4 tubes, each 15 mL), jejunum (4 tubes, each 15 mL), cecum (4 tubes,   Spearman rank correlation analysis was performed to assess the correlation between TDP and the 202 relative abundance of bacteria. The results were presented as the means ± SD, and the significant 203 and extremely significant levels were set at P < 0.05 and P < 0.01, respectively. showed non-significant difference (P > 0.05) between the groups and presented in (Table 2, 3 and 4).

Comparison TDP between Group HP and LP
215  ranging from -1 to 1. When the R value is greater than 0, the difference between groups is greater 277 than that within groups, indicating that there are differences between groups; when the P value is 278 less than 0.05, it indicates significant differences between groups. cecum and colon respectively. (Fig 3A)

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To observe the association between the bacterial relative abundance and TDP in every 346 section of the GIT, analysis of correlation was done. The results (Fig 4) displayed that in the  might also be that there was a competitive or antagonistic relationship between those bacteria 410 and phytase-producing species, and their large-scale reproduction can inhibit the growth of 411 phytase-producing microorganisms, thereby reducing the production of phytase in the GIT.

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This study found that some bacterial genera, even those located in different segments of the animal GIT, microbial mats, marshes, soda lakes, anoxic mud and marine sediments, and 430 they are highly divergent on the basis of their phylogenetic and phenotypic characteristics [47].

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A correlation between gastrointestinal bacteria and TDP in goats was found for the first 432 time in this study, which laid a foundation for screening phytase-producing strains.

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Unfortunately, this study only measured the relative abundance of bacteria but not the content 434 and activity of microbial phytase in the GIT. Therefore, it was uncertain that the improvement of 435 feed phosphorus digestibility was achieved by bacteria through the increase of phytase secretion.

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It was noteworthy that the attention of this study was focused on the bacteria, while the 437 relationship between other microorganisms, such as fungi, and host TDP was ignored. Previous