Subcutaneous Adipose Fatty Acid Profiles and Related Rumen Bacterial Populations of Steers Fed Red Clover or Grass Hay Diets Containing Flax or Sunflower-Seed

Abstract

Steers were fed 70∶30 forage∶concentrate diets for 205 days, with either grass hay (GH) or red clover silage (RC), and either sunflower-seed (SS) or flaxseed (FS), providing 5.4% oil in the diets. Compared to diets containing SS, FS diets had elevated (P<0.05) subcutaneous trans (t)-18:1 isomers, conjugated linoleic acids and n-6 polyunsaturated fatty acid (PUFA). Forage and oilseed type influenced total n-3 PUFA, especially α-linolenic acid (ALA) and total non-conjugated diene biohydrogenation (BH) in subcutaneous fat with proportions being greater (P<0.05) for FS or GH as compared to SS or RC. Of the 25 bacterial genera impacted by diet, 19 correlated with fatty acids (FA) profile. Clostridium were most abundant when levels of conjugated linolenic acids, and n-3 PUFA's were found to be the lowest in subcutaneous fat, suggestive of their role in BH. Anerophaga, Fibrobacter, Guggenheimella, Paludibacter and Pseudozobellia were more abundant in the rumen when the levels of VA in subcutaneous fat were low. This study clearly shows the impact of oilseeds and forage source on the deposition of subcutaneous FA in beef cattle. Significant correlations between rumen bacterial genera and the levels of specific FA in subcutaneous fat maybe indicative of their role in determining the FA profile of adipose tissue. However, despite numerous correlations, the dynamics of rumen bacteria in the BH of unsaturated fatty acid and synthesis of PUFA and FA tissue profiles require further experimentation to determine if these correlations are consistent over a range of diets of differing composition. Present results demonstrate that in order to achieve targeted FA profiles in beef, a multifactorial approach will be required that takes into consideration not only the PUFA profile of the diet, but also the non-oil fraction of the diet, type and level of feed processing, and the role of rumen microbes in the BH of unsaturated fatty acid.

Rumen microbiota and dietary fat: a mutual shaping

“…; Petri et al . ). On the contrary, these workers showed correlations between BH products and diverse bacteria including uncultured Prevotella , Lachnospiraceae incertae sedis , and unclassified Bacteroidales, Clostridiales and Ruminococcaceae (Huws et al .…”

“…, Anerophaga , Fibrobacter , Guggenheimella , Paludibacter and Pseudozobellia (Petri et al . ), and Acetobacter (Bainbridge et al . ).…”

“…(), Petri et al . () and Firkins and Yu (), sequencing methods have several drawbacks: most studies do not unequivocally identify species, which is a problem since some known biohydrogenating bacteria are very closely related. They measure DNA concentration, not RNA, the latter being more indicative of the microbial taxa that respond to a feeding challenge.…”

“…Experiments based on molecular fingerprints or next generation sequencing also revealed the lack of a positive relationship between B. proteoclasticus species or the Butyrivibrio genus and their expected products (Huws et al 2011;Toral et al 2012;Petri et al 2014). On the contrary, these workers showed correlations between BH products and diverse bacteria including uncultured Prevotella, Lachnospiraceae incertae sedis, and unclassified Bacteroidales, Clostridiales and Ruminococcaceae (Huws et al 2011), uncultured Lachnospiraceae or Quinellarelated bacteria (Toral et al 2012), Flavobacterium sp., Anerophaga, Fibrobacter, Guggenheimella, Paludibacter and Pseudozobellia (Petri et al 2014), and Acetobacter (Bainbridge et al 2016). As a whole, these correlation studies have not yet added clear conclusions to the generally accepted knowledge regarding bacteria involved in rumen BH or interacting with BH.…”

The trans-octadecenoic fatty acid profile of beef: Implications for global food and nutrition security

“…For example, feeding diets containing grass hay (GH) vs barley silage (Nassu et al, 2011) and red clover silage (RCS) vs GH (Mapiye et al, 2013a, Table 1) have been shown to increase the proportions VA relative to t10-18:1 in beef. Reasons for dissimilarities are unclear, but could be partially ascribed to differences in available carbohydrates, forage-borne microbes, dynamics of rumen microbes or ruminal and duodenal passage rates between these forages (Kong, He, McAlister, Seviour, & Forster, 2010;Petri, Mapiye, Dugan, & McAllister, 2014). The differences may also be partly explained by the presence of secondary plant metabolites such as tannins and polyphenol oxidase, which alter rates of PUFA biohydrogenation in the rumen (Lourenço et al, 2010).…”