<b>Quantitative analysis of rumen microbial populations by qPCR in heifers fed on <i>Leucaena leucocephala</i> in the Colombian Tropical Dry Forest

Abstract

Rumen fermentation and methanogenesis are vital metabolic processes in cattle and are carried out by microbial populations that are affected by dietary factors such as secondary metabolites, nutritional composition and degradability. The aim of this study was to monitor populations of total bacteria, total methanogens and Butirivibrio fibrisolvens in the rumen of Lucerne heifers fed on diets typical of intensive silvopastoral systems (ISS) or of a traditional (control) system. Rumen contents (RC) were collected orally from eight heifers consuming 100% Cynodon plectostachyus (control) and 76% C. plectostachyus + 24% Leucaena leucocephala (ISS) following a crossover design and DNA was extracted and quantified by quantitative PCR. Populations [Log10 (ng g-1 RC)] were 5.6 and 5.8 for total bacteria (p = 0.5343), 3.6 and 3.5 for B. fibrisolvens (p = 0.4742) and 5.0 and 5.3 for total methanogens (p = 0.2661) respectively in control and ISS diets. However, when measured in a separate parallel study, enteric methane emissions (g kg-1 of fermented dry matter) were significantly reduced with the inclusion of L. leucocephala. This fact indicated the importance of investigating the structure, function and interactions of populations beyond quantitative analysis to determine how diet affects rumen microbial populations and their function.

Chemical and in vitro evaluation of Leucaena (Leucaena leucocephala) Leaves as a Substitute of Alfalfa (Medicago sativa L.) with/without Rejected Green Banana Fruits (Musa paradisiaca)

“…Phenolic structures may disrupt protozoal membranes, inactivate protozoal enzymes, and deprive protozoa of substrates and metal ions which are essential for cell metabolism (Patra and Saxena, 2011). In the current study there was no significant difference in protozoal count among ingredients or different diets, which was in harmony with results obtained by Angarita et al (2015) and Montoya-Flores et al (2020) indicating no effects of Leucaena on rumen microbes count (bacteria and protozoa) quantified by qPCR. Moreover, Wallace et al (2015) and Saminathan et al (2016) cleared that reducing digestibility with CT diets without affecting rumen microorganisms may be attributed to the inhibition effect of CT on enzymatic activity or ruminal bacteria.…”

Effect of Dried Leaves of Leucaena leucocephala on Rumen Fermentation, Rumen Microbial Population, and Enteric Methane Production in Crossbred Heifers

“…Rumen microbiota (protozoa, bacteria, and methanogenic archaea) quantified by means of qPCR were not affected by treatments in this study. Previous investigations had obtained the same results of quantification analysis of rumen microbial populations [41,56]. One possible explanation is that some microorganisms are adapted with protective mechanisms against CT, such as the production of polymers for cellular protection and tannin degrading enzymes [17,50].…”

Performance, Rumen Microbial Community and Immune Status of Goat Kids Fed Leucaena leucocephala Post-weaning as Affected by Prenatal and Early Life Nutritional Interventions

“…Nevertheless, L. leucocephala contains toxic secondary metabolites, i.e., L -mimosine [( S )-α-Amino-β-[1-(3-hydroxy-4-oxopyridine)] propionic acid] and its digestive intermediates (isomers of hydroxypyridone; 2,3 and 3,4-DHP). The toxicity of these plant secondary metabolites could be alleviated through degradation by rumen microbes ( Akingbade et al, 2001 ; Angarita et al, 2015 ). Indeed, in several studies, performed in tropical countries, the rumen microbial community of ruminants fed L. leucocephala contained some DHP degrading bacteria such as Synergistes jonesii ( Allison et al, 1990 ), Streptococcus lutetiensis , Clostridium butyricum , and Lactobacillus vitulinus ( Dominguez-Bello and Stewart, 1991 ; Derakhshani et al, 2016 ).…”