Effect of feeding fresh forage and marine algae on the fatty acid composition and oxidation of milk and butter

Abstract

This study evaluated the effects of feeding fresh forage either as pasture plus a concentrate (PAS) or as a silage-based total mixed ration (TMR), combined with either a ruminally inert lipid supplement high in saturated fatty acids (-) or a ruminally protected microalgae containing 22 g of docosahexaenoic acid (DHA)/100 g of fatty acids (+) on the fatty acid (FA) composition and oxidation of milk and butter. For the 8 mid-lactation Holstein cows in this study, milk yield was not significantly affected by treatment, averaging 32.3 ± 1.28 kg/d. Milk fat content was higher for PAS⁻, averaging 5.05 compared with 4.10 ± 0.17% for the mean of other treatments, and was significantly depressed with microalgae supplementation (3.97 vs. 4.69 ± 0.17%). The saturated fatty acid level in the milk of cows fed TMR⁻ was significantly higher than that of the other treatments (66.9 vs. 61.2 g/100 g of FA). The level of monounsaturated FA was lowered by feeding TMR⁻ (27.4 vs. 32.0 g/100 g of FA), whereas levels of polyunsaturated FA were elevated by feeding PAS+ compared with the mean of the other treatments (6.54 vs. 5.07 g/100 g of FA). Feeding the rumen-protected microalgae increased the DHA content of milk more than 4-fold (0.06 to 0.26 g/100g of FA) with the PAS treatment. The conjugated linoleic acid content of milk was highest for PAS+ compared with the other treatments (4.18 vs. 3.41 g/100g of FA). In general, the fatty acid composition of butter followed that of milk. Overall, feeding the TMR supplemented with the rumen-protected microalgae increased the levels of volatile products of oxidation in milk and butter. No effect of forage type or microalgae supplementation was observed on the oxidative stability or antioxidant capacity of milk, although the oxidative stability of butter exposed to UV was reduced with microalgae supplementation, particularly with TMR, as assessed by using the ferric reducing ability of plasma assay.

Spirulina platensis (Arthrospira spp.): A Potential Novel Feed Source For Pasture-Based Dairy Cows

“…The positive impact of Spirulina platensis on milk yield was also confirmed by the study conducted by Šimkus et al [52]. Other studies conducted elsewhere however found no effect of feeding algal-based diet on milk yield [53][54][55][56] (Table 3).…”

“…A study by Panjaitan et al [59] found that supplementing Spirulina platensis to cattle grazing forages with low crude protein can increase the efficiency of microbial protein production in the rumen, which then can be translated into milk products. However, previous studies conducted on lactating cows using marine algal diets found that milk fat [53,56] and milk protein [59,52] were increased while others found a decreased in milk fat [54,55]. The disparities between these studies are mainly due to the different types and sources of marine algae diet used.…”

“…Feeding diet containing rich sources of longchain MUFA and PUFA to lactating cows have been shown to modify the fatty acid profiles of milk in favour of the omega-3 and omega-6 [32,62]. Previous studies conducted using dietary algal supplements have reported an increase in conjugated linoleic acid (CLA) [53], whereas Glover et al [54] found decreases in monounsaturated fatty acids in milk fat. Stamey et al [56] found that supplementation of dairy cows with conjugated linoleic acid significantly increased the proportions of trans-18:1 and Trans-11 18:1 fatty acids.…”

“…Moates et al [55] Consuming 20% docosahexaenoic acid algal meal had no effect on milk yield but decreased milk fat Boeckaert et al [53] Cows consuming algal rich diet had decreased dry matter intake and milk yield, but the conjugated linoleic acid concentration was increased Glover et al [54] Milk yield of cows consuming algae was not significantly affected but milk fat was significantly lowered…”

Conjugated Linoleic Acid in Milk and Fermented Milks: Variation and Effects of the Technological Processes

“…Since the concentration of these fatty acids is relatively low for providing health benefits, significant efforts have been devoted to increasing their content in milk and dairy products, in order to produce foodstuffs with improved nutritional value. The main employed strategies are based on the manipulation of the feed and dietary regimen of the animals, and on the modification of the technological processes used in the manufacture of dairy products (6)(7)(8).…”