Effects of forage species and stage of maturity on bovine milk fatty acid composition

Abstract

Effects of forage species and stage of maturity on bovine milk fatty acid compositionFive cows were used in a 565 Latin square to evaluate the effects of forage type and stage of herbage maturity on milk fatty acid (FA) composition. Four silages were prepared from primary growths of timothy-meadow fescue and red clover swards at an early and late stage of growth. Treatments consisted of these silages and an additional treatment comprised of an equal mixture of late-cut grass silage and early-cut red clover silage. Forages were fed ad libitum and supplemented with 9 kg/day of a standard concentrate. Compared with grass silage, red clover silage diets enhanced milk fat monounsaturated FA (MUFA) and polyunsaturated FA (PUFA) content, 18:3 n-3 in particular, responses that were associated with concomitant reductions in 10:0 to 16:0 concentrations. Decreases in 16:0 and increases in PUFA concentrations were more pronounced for early than late growths of red clover. Even though red clover resulted in marginal increases in total milk fat trans 18:1 content, milk trans-11 18:1 concentrations were lower for red clover than for grass silage diets. It is concluded that replacing grass with red clover silage prepared at an early stage of maturity represents a sustainable nutritional strategy for enhancing the MUFA and PUFA content of milk.

The effect of N-fertilisation rate or inclusion of red clover to timothy leys on fatty acid composition in milk of dairy cows fed a commercial silage : concentrate ratio

“…In the latter study, in a mix of grass and red clover (50 : 50 on DM basis), the concentrations were 2.9 and 7.0 g/kg DM for 18:2n-6 and 18:3n-3, respectively. In the current study, the FA concentrations in silages were comparable with those from the study by Dewhurst et al (2003a), whereas the concentrations in grass silages were approximately half of the concentrations found by Vanhatalo et al (2007). The differences could partly be because of oxidative losses of FAs during wilting, as the material was wilted overnight in the current study compared with the relatively short wilt (3 h for grass) by Vanhatalo et al (2007).…”

“…The RC-G was rather similar to G-30 in proportions of the FAs presented in Table 3. Previous reports of FA concentrations in grass and red clover silages differed between experiments, for example, Vanhatalo et al (2007) reported concentrations of 18:2n-6 and 18:3n-3 to be 4.4 and 11.6 g/kg DM in grass silage and 5.7 and 14.2 g/kg DM in red clover silage, respectively, whereas Dewhurst et al (2003a, experiment 1) found them to be 2.4, 7.7, 3.7 and 6.2 g/kg DM for 18:2n-6 and 18:3n-3 in grass silage and red clover silage, respectively. In the latter study, in a mix of grass and red clover (50 : 50 on DM basis), the concentrations were 2.9 and 7.0 g/kg DM for 18:2n-6 and 18:3n-3, respectively.…”

“…Compared with grass silage, red clover silage has a lower NDF concentration and a higher rumen passage rate (Vanhatalo et al, 2007). Further, red clover has been shown to have lower lipolytic activities, or to protect the FA against lipolysis through encapsulation in protein-phenol complexes (Van Ranst et al, 2011).…”

Red clover polyphenol oxidase and lipid metabolism

“…Second, the difference in rumen digestion kinetics between red clover and other forages could reduce residence time in the rumen and thus indirectly reduce biohydrogenation. Vanhatalo et al (2007) postulated that protection of PUFA in red clover diets was a result of a combined effect of PPO protection and altered digestion kinetics with a higher rate of ruminal digestion of fibre for red clover as opposed to grass silage. This would suggest a reduction in ruminal retention time resulting in a higher proportion of dietary lipids escaping metabolism in the rumen.…”

Fertility and growth of nulliparous ewes after feeding red clover silage with high phyto-oestrogen concentrations

“…Lambs fed with red clover had higher live-weight gain compared with lambs grazing lucerne or perennial ryegrass pastures (Speijers et al, 2005). Dairy cows fed with red clover silage have higher DM intake, higher milk yield and are associated with a more desirable polyunsaturated fatty-acid milk composition in comparison with cows fed grass silage (Dewhurst et al, 2003;Vanhatalo et al, 2006 and2007).…”