Higher Fatty Acid Composition of Immature Forages as Affected by N Fertilization¹

Abstract

High levels of both N and total higher fatty acids (HFA) in forage have been associated with increasing the grass tetany hazard to grazing cattle. The objective of this study was to determine the relationship between forage N, total HFA, and HFA species distribution in several forages.Forage N, ETA, MIAspecies concentration, and total chlorophyll were determined in immature vegetative growth of Agropy,con desertorum (Fisch.) Schult., Cynodon dactylon L., Loliutn perenne L., Trifoliunt repent L., and Trillcum aestiuson L. established with soil fertility levels up to 500 ppm N in the growth chamber. Forage HFA concentrations were positively and linearly related to forage N levels, but regression coefficients were not the same for all species. The HFA concentrations were as high as 16 mmol COOH/100g DM at 6% total N in first cutting Lolium perenne L. The relative HFA species distribution was the same within a given forage, even though total N concentrations ranged from 2 to 6%. The mean HFA specie concentrations (determined by gas-liquidchromatography relative to mean total HFA concentrations determined by titration) when expressed as percent for the grasses were: C14:0 -2 q , C16:0 -13%, C16:1 -1 q , C18:0 plus C18:1 -1%, C18:2 -11%, and C18:3 -67%. The total HFA concentrations were positively correlated with chlorophyll a + b concentrations which was expected, since the HFA of green plants is largely associated with chloroplast membrane.

Fatty acid profile in two berseem clover (Trifolium alexandrinum L.) cultivars: Preliminary study of the effect of part of plant and phenological stage

“…Leaves are the main site of lipid synthesis in the plant probably due to a higher content of chloroplasts (Hawke 1973;Sasikala et al 2013), if compared to stems. In fact, CP content is positively correlated with total FA content (R 2 = 0.78; P < 0.001 data not shown), and with total UFA content (R 2 = 0.75; P < 0.01) ( Figure 3) probably as result of the higher efficiency of lipid synthesis in the leaves than in stems, as reported by Mayland et al (1976). In fact a positive relationship has been found between chlorophyll and total FA, included PUFA in plant (Dierking et al 2010), and it is probable that chlorophyll will be an important criterion in plant breeding for manipulation of FA levels.…”

“…In fact, CP content is positively correlated with total FA content ( R 2 = 0.78; P < 0.001 data not shown), and with total UFA content ( R 2 = 0.75; P < 0.01) (Figure ) probably as result of the higher efficiency of lipid synthesis in the leaves than in stems, as reported by Mayland et al . (). In fact a positive relationship has been found between chlorophyll and total FA, included PUFA in plant (Dierking et al .…”

Meat quality and fatty acid composition of pasture-finished beef steers fed barley and soybeans

“…The fatty acid composition was characterized by higher concentration of C18:3 and lower concentration of C16:0 compared with other reports (Mayland et al 1976;Molloy et al 1978;Boufaied et al 2003a). Many factors can influence the fatty acid concentration and composition of forages including species, maturity, fertility and season (Boufaied et al 2003a).…”

“…These conditions, such as high ruminal pH, active cellulolytic bacteria, and high rate of passage (Martin and Jenkins 2002;Lee et al 2003), are associated with pasture feeding. Further, forages typically contain high concentrations of PUFA (Mayland et al 1976;Molloy et al 1978;Boufaïed et al 2003a). Thus, pasture of high nutritive value is one of the most effective diets for elevating CLA and PUFA content of both milk (Kelly et al 1998) and meat (French et al 2000).…”

Fatty acid concentrations in timothy (Phleum pratenseL.) and meadow fescue (Festuca pratensisHuds.): Effects of seasonal variations at different nitrogen fertilization levels

“…Boufaïed et al (2003) found that concentrations of palmitic acid (C16:0), C18:2n-6, C18:3n-3 and TFAs were higher in timothy (Phleum pretense L.) fertilized with 120 kg N ha (1 than in controls that received no N-fertilization. In addition, Barta (1975) and Mayland et al (1976) found positive correlations between the N-fertilization level and concentrations of TFA in a range of species. Boufaïed et al (2003) also observed that the reductions in the levels of certain FAs (C16:1 and C18: 3n-3) with maturity occurred at a later growth stage in timothy fertilized with N.…”