Grazed chicory, plantain or ryegrass–white clover alters milk yield and fatty acid composition of late-lactating dairy cows

Abstract

The aim of the present research was to compare milk fatty acid composition of cows grazing perennial ryegrass–white clover pasture (RGWC), with that of cows grazing alternative forages of chicory or plantain. Fifty-four cows, balanced for milk solids, days in milk and bodyweight, were divided evenly into replicated groups of six cows/group. Cows grazing chicory or plantain had similar estimated dry-matter intake (17.7 kg DM/cow.day) and milk-solid (MS) yield (1.93 kg MS/cow.day), which were greater (P < 0.05) than for cows grazing RGWC (15.6 kg DM/cow.day and 1.65 kg MS/cow.day). Milk produced from cows grazing chicory or plantain contained greater proportions of omega-3 fatty acids (FA) than that from cows on RGWC (P < 0.01), despite lower omega-3 FA in herbage. RGWC increased the percentage of conjugated linoleic and vaccenic acids in milk compared with those of milk produced from herbs (P < 0.01). This reflects the greater percentage of α-linolenic acid in RGWC (P ≤ 0.02) than in forage herbs. The changes in FA profile from the herbage to the milk suggests less biohydrogenation in cows grazing the herbs. Forage herbs demonstrated the potential benefit to alter milk FA composition, while increasing milk production.

Rumen Fermentation and Fatty Acid Composition of Milk of Mid Lactating Dairy Cows Grazing Chicory and Ryegrass

“…This is the second study in a series of experiments investigating the effect of high moisture forages on the production and quality of milk and associated environmental impacts in pastoral dairy systems. Our first proof-of-concept study showed that under pastoral grazing feeding high moisture, herb diets altered milk FA composition without affecting production [19]. The results of the present study confirm the positive effect of feeding CH on PUFA and demonstrate that producers can influence FA composition through changes in feeding regimes.…”

“…It is interesting that feeding reproductive CH at 55-58% of the diet of mid lactating dairy cows increased milk production compared to the control-feeding regime, a result similar to previous findings when CH was fed while vegetative [19,20]. Muir et al [30], on the other hand, did not observe any differences in milk production between the control ryegrass and reproductive CH at 50% of the diet in summer.…”

“…Our results confirm that, regardless of time of allocation, feeding CH at up to half the ration increases concentrations of beneficial FA; LA and ALA, in the milk of dairy cows compared with the traditional feeding regime of RGWC [19,24,30]. The increase in the concentration of these is particularly important given their human health benefits.…”

“…Chicory contains more readily fermentable carbohydrates (non-fibre carbohydrates; NFC) than ryegrass/white clover (Lolium perenne L./Trifolium repens L.; RGWC) herbage [18], which may increase the concentration of total VFA and lower rumen pH during ruminal fermentation. In our earlier proof-of-concept research, elevated PUFA were recorded from late lactation cows fed pasture diets of CH compared with the control RGWC in a grazing study [19]. Feeding CH, as all or as part of a ration, has also shown milk yield improvements [20,21] and nitrogen loss reductions [18,22,23] compared to traditional ryegrass pastures.…”

Can alternative forages substantially reduce N leaching? findings from a review and associated modelling

“…However, Wang et al (2015) noticed, in insect herbivores feeding on plantain, an increase in IG did not reduce intake rate but lowered growth rate, leading to the suggestion that PSM reduce the efficiency of nutrient utilisation. Interestingly, a similar effect has occasionally been observed in dairy cows grazing plantain or grass-clover pastures as a control, whereby greater apparent intake was measured for plantain but milk production was similar to the control (Box et al 2017b;Mangwe et al 2018). The theory that PSM may alter intake and nutrient use efficiency has been explored in greater detail for phenolics such as condensed tannins which will be addressed later in this review.…”