Contribution of rumen protozoa to duodenal flow of nitrogen, conjugated linoleic acid and vaccenic acid in steers fed silages differing in their water-soluble carbohydrate content.

The present experiment was designed to estimate the quantitative contribution of rumen protozoa to the total N, conjugated linoleic acid (CLA) and vaccenic acid (VA; trans-11-18 : 1) flow to the duodenum of steers fed two silage diets: control silage (CS) and silage high in water-soluble carbohydrates (HS). Protozoal duodenal flows were estimated using a real-time PCR assay to quantify the genes encoding protozoal 18S ribosomal RNA. Denaturing gradient gel electrophoresis was used to confirm that the rumen protozoa populations were similar to the protozoal population flowing to the duodenum. Estimated duodenal flow of protozoal N was 14.2 and 18.2 g/d (P>0.05) for animals fed the CS and HS diets respectively. Protozoal flow thus represented between 12 and 15 % of the total N duodenal flow. In terms of fatty acid flow, protozoa accounted for between 30 and 43 % of the CLA and 40 % of the VA reaching the duodenum. The contribution of protozoa to 16 : 0 and 18 : 0 flows to the duodenum was less than 20 and 10 %, respectively. These results show that the fatty acids within protozoa make up a significant proportion of the CLA and VA reaching the duodenum of ruminants.

High-throughput metabolic fingerprinting of legume silage fermentations via Fourier transform infrared spectroscopy and chemometrics.

Silage quality is typically assessed by the measurement of several individual parameters, including pH, lactic acid, acetic acid, bacterial numbers, and protein content. The objective of this study was to use a holistic metabolic fingerprinting approach, combining a high-throughput microtiter plate-based fermentation system with Fourier transform infrared (FT-IR) spectroscopy, to obtain a snapshot of the sample metabolome (typically low-molecular-weight compounds) at a given time. The aim was to study the dynamics of red clover or grass silage fermentations in response to various inoculants incorporating lactic acid bacteria (LAB). The hyperspectral multivariate datasets generated by FT-IR spectroscopy are difficult to interpret visually, so chemometrics methods were used to deconvolute the data. Two-phase principal component-discriminant function analysis allowed discrimination between herbage types and different LAB inoculants and modeling of fermentation dynamics over time. Further analysis of FT-IR spectra by the use of genetic algorithms to identify the underlying biochemical differences between treatments revealed that the amide I and amide II regions (wavenumbers of 1,550 to 1,750 cm(-1)) of the spectra were most frequently selected (reflecting changes in proteins and free amino acids) in comparisons between control and inoculant-treated fermentations. This corresponds to the known importance of rapid fermentation for the efficient conservation of forage proteins.

Pathogens in livestock waste, their potential for movement through soil and environmental pollution.

Livestock wastes contain many pathogenic microorganisms including bacteria, viruses and protozoa. Following the application of these wastes to land the potential exists for environmental contamination. Plants, soil and ultimately water courses which may subsequently be used as catchments for public water supplies may all be affected. Research attention is now being focused on this possibility, especially in the case of protozoan pathogens which may be the most important as they are often resistant to current methods used in public water treatment. In this review we highlight some of the many factors that are likely to influence the degree of pollution by their effect on both the vertical and horizontal transport of microorganisms through soil. Soil pH, temperature, the presence of plants, microbial surface properties, type of waste, soil type and soil water content and flow may all affect the rate and extent of vertical transport, with the latter two generally considered to be the most important. Lateral movement is a particular problem in soils with impermeable substrata or in waterlogged conditions and in these cases the major factors affecting movement include rainfall rate, topography of the land and the rate at which microorganisms partition into the runoff.