Effects of oilseed supplements on milk production and quality in dairy cows fed a hay-based diet

Abstract

The influence of rapeseed (Brassica napus L.) and linseed (Linum usitatissimum L.) on feed consumption, milk yield, composition and fatty acid (FA) profile was investigated in lactating dairy cows. According to a Latin square design, twelve cows were assigned to three experimental settings which received a haybased diet supplemented with one of the following mixtures: cracked barley (1.0 kg) and cracked maize (0.5 kg) as Control diet (C-diet); full fat ground rapeseed (1.0 kg), cracked barley (1.0 kg) and cracked maize (0.5 kg) as Rapeseed diet (R-diet) and extruded linseed (1.2 kg), cracked barley (1.0 kg) and cracked maize (0.5 kg) as Linseed diet (L-diet). Diet supplemented with rape- and linseed did not affect dry matter intake. As result of the high amount of dietary ether extract R- and L-diet showed higher crude fat intake as compared to the control. Despite the higher intake of crude fat and, in particular, of the polyunsaturated fraction, milk yield and composition resulted similar among treatments. Compared to C-diet, R-diet resulted in milk containing significantly lower amounts of saturated fatty acids (SFA) (60.9 vs 66.9% of total detected SFA) as well as higher amounts of monounsaturated fatty acids (MUFA) (30.6 vs 24.2%). However, R-diet had no effect on polyunsaturated fatty acid content (PUFA). With respect to C-diet, L-diet also significantly reduced the content of SFA (59.8 vs 66.9%) and increased both MUFA (29.1 vs 24.2%) and PUFA (4.7 vs 4.1%) contents. Feeding about 1 kg of whole oilseeds per head per day had no clear effects on milk vaccenic acid and conjugated linoleic acid contents. The inclusion of rapeseed in the diet significantly reduced the content of n-6 FA in the milk, whereas the linseed-supplemented diet significantly increased the content of n-3 FA. In comparison to C-diet, n-6/n-3 ratio was lower in L-diet milk and intermediate in R-diet milk. Feeding lactating dairy cows with oilseeds rich in unsaturated fatty acids (UFA) did not exert any effects on productive performance. Considering the increase in PUFA and the reduction of n-6/n-3 ratio as a desirable enrichment of milk fat for human health, under our experimental condition feeding linseed appears to improve the nutritional value of milk better than rapeseed

Improving the fatty acid profile of winter milk from housed cows with contrasting feeding regimes by oilseed supplementation

“…In contrast to linseed, rapeseed supplementation only increased concentrations of MUFA, OA (the dominant FA found in rapeseed oil), VA and RA, but did not affect the total and individual n-3, thus being in line with previously reported results (Glasser et al, 2008), although some studies report no effect of rapeseed feeding on milk VA and RA concentrations (Collomb et al, 2004;Egger et al, 2007). Differences in the impact of linseed and rapeseed supplementation on milk FA profiles were expected, since: (a) the dominant FA differ -ALA in linseed as opposed to OA in rapeseed (Glasser et al, 2008) and (b) higher ALA intakes result in more ALA escaping RBH and being secreted into milk (Collomb et al, 2004;Egger et al, 2007).…”

Effect of unsaturated fatty acid supplementation on performance and milk fatty acid profile in dairy cows fed a high fibre diet

“…As expected, this level of DMI was slightly lower than data observed in other comparable studies (Abel-Caines et al, 1998;Bailoni et al, 2004) and most likely this was related to the high level of NDF as reported by Egger et al (2007). The NDF intake was not affected and averaged 1.06% of BW; this finding was lower than the value reported by Rayburn and Fox (1993) and the level of intake (1.1-1.2 NDF Intake %BW) indicated by Mertens (1987).…”

“…Vaccenic increased 6.2-and 4.5-fold (P<0.001); its concentration in milk depended both on its level in the gut and on its conversion in CLA in the udder (Corl et al, 2001;Antongiovanni et al, 2003). In this study, the percentage of CLA in milk was quite low for both diets ( Table 7) when compared with other studies (0.7-1.3%) (Kay et al, 2005;Pottier et al, 2006;Egger et al, 2007). This was probably due to the high level of dietary fibre which leads to a high ruminal pH which, as suggested by Piperova et al (2002), is related to a lower production of BH intermediate compounds; this means a low vaccenic acid supply at duodenal level.…”

“…Recent studies (Bailoni et al, 2004;Egger et al, 2007) on high productive dairy cow nutrition pointed out that dietary unsaturated fatty acids (UFA) may influence the milk fatty acids (FA) profile, lowering the content of saturated FA (SFA), such as lauric (C12:0), miristic (C14:0) and palmitic acid (C16:0). Moreover, the high level of dietary polyunsaturated FA (PUFA) has been demonstrated increasing the milk content in PUFA and, among them, in linoleic conjugated acids (CLA) (Kelly et al, 1998;Dhiman et al, 1999;Khanal and Dhiman, 2004;Ponter et al, 2006).…”

Relationship between milk fatty acid composition and dietary roughage source in dairy cows

“…In dairy cows, the source of roughage affects the organoleptic and nutritional quality of milk, particularly the fatty acid (FA) profile (Shingfield et al 2005;Egger et al 2007). Differences between grass hay (GH) and maize silage (MS) are evident in single FA contents.…”