Flowering catch crops used as forage plants for dairy cows: Influence on fatty acids and tocopherols in milk

Abstract

The effect of several flowering dicotyledonous catch crop plants (dicots) on milk fat quality in cows was investigated to test the hypothesis that their phenolic compounds may inhibit ruminal biohydrogenation and thus enhance the transfer to milk of intact, plant-derived polyunsaturated fatty acids. Berseem clover (Trifolium alexandrinum), buckwheat (Fagopyrum esculentum), and phacelia (Phacelia tanacetifolia) were sown in mixture with ryegrass (Lolium multiflorum; intended biomass proportion of 0.2) on 1ha. For comparison, nonflowering chicory (Cichorium intybus, also sown in mixture with ryegrass) and pure ryegrass were cultivated. Realized biomass proportions (wet weight) were 91% for berseem clover, 69% for buckwheat, 54% for phacelia, and 51% for chicory. At the start of flowering (or from d 47 after sowing onward), cultures were harvested daily and fed for 20 d ad libitum to groups of 6 midlactation cows each. Additionally, 1 kg each of energy and protein concentrate and pure ryegrass hay were fed. Individual intake and milk yield of the cows were measured daily. Milk samples were obtained twice daily 5 d before and from 11 to 20 d after the start of treatment feeding. Feed samples were drawn twice a week from the fresh feeds. Apart from standard traits, feeds and milk were analyzed for fatty acids, tocopherols, and phenolic fractions. Only a few substantial treatment effects on intake and performance were observed. All diets based on dicots increased α-linolenic acid (ALA) concentrations in milk fat compared with the ryegrass diet even though the corresponding swards were not generally richer in ALA. The highest ALA concentration in milk fat (1.3 g/100g of fatty acids) occurred with the berseem clover diet. Transfer rate of ALA from feed to milk was highest with the buckwheat diet (0.09) and lowest with ryegrass (0.05). This was congruent with the differences in total extractable phenols, being high in the buckwheat sward (2.6% of dry matter) and low in the ryegrass sward (1.2% of dry matter). Intermediates of ALA biohydrogenation were lowest in the milk fat of the buckwheat group, indicating an inhibitory effect of this treatment, which provided the highest dietary levels of phenols. The α-tocopherol concentration in milk was higher with the buckwheat diet than with berseem clover and phacelia diets. The study provides evidence that the ALA concentration in milk fat could be enhanced by feeding flowering dicots; however, this was due to different modes of action.

Browsing ratio, species intake, and milk fatty acid composition of goats foraging on alpine open grassland and grazable forestland

“…Comparable results have been repeatedly reported in the literature (among others, Kälber et al, 2011;Mancilla-Leytón et al, 2013) and may be ascribed to the low and step-decreasing efficiency of ALA metabolism to more unsaturated and long-chain members of the omega-3 FA family (Bernal-Santos et al, 2010). According to the lack of significant difference in LA concentration between OG and GF milk samples, long-chain omega-6 PUFA deriving from LA metabolism were also unaffected by the vegetation type fed by the goats.…”

“…The concentrations of the various detected phenolic fractions of the ingested OG and GF vegetation types (as well as the relative difference between treatments) were reported to be high enough to significantly affect rates and extents of ruminal BH and transfer of FA to milk and meat in cows and sheep (Kälber et al, 2011;Willems et al, 2014). Thanks to salivary defense mechanisms and ruminal microbial degradation of PC, goats are much less sensitive to plant antinutritional factors and are able to consume forages containing much more polyphenols than other ruminants (Silanikove, 1997).…”

“…Theoretically, the fact that GF milk tended to contain a higher concentration of ALA may also suggest a higher ruminal bypass of dietary ALA in its intact form due to a reduced BH rate. In recent published trials, both ALA and LA contents in ruminant milk and meat were found to be positively correlated with type and relative abundance of dietary polyphenols (Kälber et al, 2011;Willems et al, 2014), the latter being potentially able to inhibit hydrogenating microorganisms in the rumen (Leiber et al, 2005). Tanniferous (2011) reported that in vitro incubations with ruminal fluid of alpine (high polyphenols) compared to lowland (low polyphenols) origin increased significantly the apparent net production and proportion…”

“…Hydrolysable tannins (HT) were estimated as the difference between TT and CT; the obtained values are of limited accuracy due to the different standards used, but such computation represents a common procedure (Kälber et al, 2011;Khiaosa-Ard et al, 2011;Willems et al, 2014).…”

Influence of different morphological parts of buckwheat (Fagopyrum esculentum) and its major secondary metabolite rutin on rumen fermentation in vitro

“…in total phenols (Broudiscou et al, 2000;Fraisse et al, 2007;Kälber et al, 2011). Common buckwheat (Fagopyrum esculentum) is a dicotyledonous crop plant growing in temperate regions which contains comparably high concentrations of phenolic compounds (Hinneburg and Neubert, 2005).…”