Changes in goat milk fatty acids during abrupt transition from indoor to pasture diet

Abstract

14Goal of this study was to evaluate the kinetics of goat milk fatty acids during abrupt 15 transition from indoor to pasture-based diets. Twelve Valdostana goats in mid-lactation 16 reared indoors and fed hay and concentrates for 40 days were abruptly brought outdoors 17 on natural pasture and fed fresh grass ad libitum. Feed samples and individual milk 18 samples were collected for fatty acids analysis on the last day of indoor feeding (day 0) 19 and after 1, 2, 3, 4, 6, 9, 13, 18 and 23 days of fresh grass feeding. Milk fatty acid 20 composition was significantly affected by sampling day. Significant changes already took 21 place few days after transition. The most marked and consistent variations occurred at the 22 expense of some unsaturated fatty acids. Total trans-octadecenoic and trans-23 octadecadienoic acids, conjugated linoleic acids (CLA) and omega-3 fatty acids constantly 24 increased, reaching concentrations 4.0, 3.0, 3.9, and 2.2 times higher at the end of the trial 25 than at its beginning, respectively. On the last sampling day the omega-6/omega-3 fatty 26 *Manuscript 2 acids ratio was two times lower than its initial value. Considering individual fatty acids, 27 the most consistent and remarkable increasing trends throughout the trial were observed 28 for C18:1 t6-11, C18:1 t12-14+c6-8, C18:1 c14+t16, C18:2 t11c15, C18:2 c9t13+t8c12, 29 CLA isomers c9t11+t7c9+t8c10 and t11c13+c9c11. Alpha-linolenic and eicosapentaenoic 30 acids also increased significantly, but to a lesser extent. In view of the many beneficial 31 biological effects that have been attributed to vaccenic acid (C18:1 t11), rumenic acid 32 (C18:2 c9t11), and omega-3 fatty acids, results showed that, from a human health 33 perspective, goat milk fatty acid composition consistently improved after transition from 34 indoor to pasture feeding. Such improvements, mainly due to the high content of -35 linolenic acid in pasture plants, were already significant after two or three days of fresh 36 grass feeding. Further increases of beneficial fatty acids in milk fat were observed till 37 about thirteen (vaccenic acid and CLA) or twenty-three (omega-3 fatty acids) days after 38 transition. These results show that pasture can be considered a natural feeding strategy to 39 quickly enhance the healthfulness of goat milk fat. The positive effects of fresh grass-based diets on the fatty acid (FA) profile and the 45 nutritional quality of dairy fat have been recognized broadly (Morand-Fehr et al., 2007). 46 Such improvement is related to both increased milk concentrations of polyunsaturated FA 47 (e.g., omega-3 FA and conjugated linoleic acid) which are known to exert many putative 48 beneficial effects for human health (Barcelo-Coblijn and Murphy, 2009; Benjamin and 49 Spener, 2009) and decreased concentrations of saturated FA (particularly lauric, myristic, 50 and palmitic acids) able to raise risk factors for cardiovascular diseases (Ohlsson, 2010). 51Modifications and persistency of ruminant milk FA concentrations determined by ...

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

“…It is well known that fresh grass feeding positively affects the lipid fraction of goat milk by enhancing the presence of health-promoting fatty acids (FA) (e.g.,rumenic and vaccenic acids, and contemporarily lowering the omega-6/omega-3 FA ratio and the levels of specific FA considered detrimental for human health (e.g., hypercholesterolaemic medium-chain saturated FA) (Renna et al, 2012a(Renna et al, , 2012bMancilla-Leytón et al, 2013). Besides that, in the last decade it has also been repeatedly demonstrated that the FA composition of milk and cheese from grazing ruminants may be significantly influenced by the botanical composition of the ingested plants (among others, Collomb et al, 2002;Di Trana et al, 2005;Renna et al, 2014a).…”

“…The same group of goats foraged on both vegetation types to exclude confounding effects related to differences in selection behaviour among individuals (Provenza et al, 2003). To minimize the effect of the physiological stage of the animals on their intake behaviour, the time period between OG and GF exploitation was reduced at the minimum (22 days) required to adapt to such different vegetation types, especially for stabilization of FA in goat milk fat (Renna et al, 2012b). For the latter purpose, before entering the enclosures the goats grazed for three weeks two grazing lands dominated by grasses and shrubs similar to OG and GF, respectively.…”

Effects of season on the quality of Garfagnina goat milk

“…In fact, grazing improves the milk's characteristics, also due to the increased concentrations of polyunsaturated fatty acids (PUFA) in milk (e.g. omega-3 FA and conjugated linoleic acid), which are known to have many beneficial effects on human health (Biondi et al 2008;Renna et al 2012;Albenzio et al 2016). Omega-3 (n-3) fatty acids (FAs) are involved in the development of brain and retinal tissues and in the progression and prevention of human pathologies, including heart disease and some cancers (Blondeau 2016).…”

Quick changes of milk fatty acids after inclusion or suppression of linseed oil in the diet of goats

“…previously reported increases of these FA levels 12 h after LO supplementation in dairy goats. Further investigations have reported increases 24 h after feeding diets rich in α ‐linolenic acid . The trends of cis ‐9, trans ‐11, cis ‐15 18:3 contents in milk fat (Table ) reflected those of α ‐linolenic acid.…”