Influence of damaging and wilting red clover on lipid metabolism during ensiling and in vitro rumen incubation

This paper describes the relationship between protein-bound phenols in red clover, induced by different degrees of damaging before wilting and varying wilting duration, and in silo lipid metabolism. The ultimate effect of these changes on rumen biohydrogenation is the second focus of this paper For this experiment, red clover, damaged to different degrees (not damaged (ND), crushing or frozen/thawing (FT)) before wilting (4 or 24 h) was ensiled. Different degrees of damaging and wilting duration lead to differences in polyphenol oxidase (PPO) activity, measured as increase in protein-bound phenols. Treatment effects on fatty acid (FA) content and composition, lipid fractions (free FAs, membrane lipids (ML) and neutral fraction) and lipolysis were further studied in the silage. In FT, red clover lipolysis was markedly lower in the first days after ensiling, but this largely disappeared after 60 days of ensiling, regardless of wilting duration. This suggests an inhibition of plant lipases in FT silages. After 60 days of ensiling no differences in lipid fractions could be found between any of the treatments and differences in lipolysis were caused by reduced FA proportions in ML of wilted FT red clover Fresh, wilted (24 h) after damaging (ND or FT) and ensiled (4 or 60 days; wilted 24 h; ND or FT) red clover were also incubated in rumen fluid to study the biohydrogenation of C18:3n-3 and C18:2n-6 in vitro. Silages (both 60 days and to a lower degree 4 days) showed a lower biohydrogenation compared with fresh and wilted forages, regardless of damaging. This suggests that lipids in ensiled red clover were more protected, but this protection was not enhanced by a higher amount of protein-bound phenols in wilted FT compared with ND red clover The reduction of rumen microbial biohydrogenation with duration of red clover ensiling seems in contrast to what is expected, namely a higher biohydrogenation when a higher amount of FFA is present. This merits further investigation in relation to strategies to activate PPO toward the embedding of lipids in phenol protein complexes

Copper Status of Free Ranging Cattle: What’s Hidden Behind? A Pilot Study at the Gilgel Gibe Catchment, Ethiopia

Copper (Cu) deficiency is known to be a major risk for cattle health and production. The widespread problem is due to low absorption rates in the rumen, low Cu concentrations in the natural diet and the presence of dietary Cu antagonists, such as S, Mo and Fe (Suttle 2010). Cattle in the tropics are even more prone to shortage of this mineral, given that the animals are often extensively kept and largely dependent on natural pasture for mineral supply (McDowell and Arthington, 2005). More specifically, in Ethiopia, Cu deficiency was previously described in zebu (Bos indicus) cattle by several authors (e.g. Dermauw et al.). Similar to other minerals, Cu is part of the soil-plant-animal chain, with many factors influencing Cu concentrations at every level. In our study, the overall goal was to investigate the possible influence of certain environment and management factors on dietary concentrations of Cu and antagonists and Cu status in free ranging cattle