Diet, rumen biohydrogenation and nutritional quality of cow and goat milk fat

Abstract

Diet, rumen biohydrogenation and nutritional quality of cow and goat milk fatThe potential to modify the milk fatty acid (FA) composition by changing the cow or goat diets is reviewed. Ruminal biohydrogenation (RBH), combined with mammary lipogenic and D-9 desaturation pathways, considerably modifies the profile of dietary FA and thus milk composition. The pasture has major effects by decreasing saturated FA and increasing FA considered as favorable for human health (c9-18:1, 18:3n-3 and c9t11-CLA), compared to winter diets, especially those based on maize silage and concentrates. Plant lipid supplements have effects similar to pasture, especially linseed, but they increase to a larger extent, simultaneously several trans isomers of 18:1 and, conjugated or non-conjugated 18:2, especially when added to maize silage or concentrate-rich diets. The goat responds better for milk 18:3n-3 and c9t11-CLA, and sometimes less for c9-18:1, and is less prone to the RBH trans-11 to trans-10 shift, which has been shown to be time dependent in the cow. The respective physiological roles of most milk trans FA have not been studied to date, and more studies in rodents and humans fed dairy products modified by changing ruminant diet are required before recommending a larger use of lipid sources and how to combine them with the different feeding systems used by dairy farmers.Keywords: Diet composition, biohydrogenation intermediates, mammary metabolism, fatty acid desaturation, milk fatty acids. 828 DOI 10.1002/ejlt.200700080 Eur. J. Lipid Sci. Technol. 109 (2007 IntroductionMilk fat secretion and milk fatty acid (FA) composition are of great interest with regard to human nutrition. Apart from their contribution to dairy products' sensorial quality and to the amount of dietary energy, different lipid and FA compounds (short-and medium-chain saturated, branched, mono-and polyunsaturated, cis and trans, conjugated FA, etc.) present in ruminant milk fat are indeed potentially positive or negative factors for the health of consumers [1][2][3].Dairy products provide indeed 25-60% of the overall saturated fat consumption in Europe, which makes them, since decades, a target of dieticians' criticism due to the negative effects of excessive consumption of saturated FA on human health [4]. The image of saturated FA should, however, be weighed by the fact that C 12 -C 16 saturated FA are thought to be atherogenic only when consumed in excessive amounts, that 18:0 has no atherogenic effect and that saturated fat could even be protective when compared to a low-fat, high-carbohydrate diet [5,6]. The allegedly atherogenic effect of certain trans monounsaturated FA (MUFA) [7] has not been confirmed for vaccenic acid (t11-18:1), the main isomer present in milk [8,9]. The intake of some trans isomers of 18:2 seems to be particularly harmful, although further research is needed to discriminate between industrial and ruminant isomer profiles [10]. In other respects, it has been shown in humans that the consumption of milk fat [11] could sometimes d...

Effect of replacing grass silage with maize silage in the diet on bovine milk fatty acid composition

“…Previous studies have shown that MS-based rations containing no additional lipid supplements increase the milk fat CLA content when compared with GS-based rations Nielsen et al, 2006;Chilliard et al, 2007). In the present study, replacing GS with MS resulted in a quadratic increase in milk fat CLA.…”

“…found between diets higher in soluble sugars and butyrate production by protozoa (Chilliard et al, 2007). In this study, the water-soluble carbohydrate intake did increase with increasing MS inclusion.…”

“…Previous research has established that nutrition has a major influence on milk FA composition (Givens and Shingfield, 2006;Chilliard et al, 2007) and that high forage diets can be used to enhance milk PUFA concentrations . The current study served to extend these findings by providing a detailed assessment of the impact of replacing GS with MS as part of a TMR on animal performance and milk FA composition.…”

“…Numerous studies have examined the impact of oilseeds, plant oils, marine lipids and proportion of forage in the diet on milk fat composition (Givens and Shingfield, 2006;Chilliard et al, 2007), but research examining the role of forages in the diet on milk fat composition is relatively limited Ferlay et al, 2006). In northern Europe, maize silage (MS) and grass silage (GS) are the major conserved forages used for milk production (Wilkinson et al, 1996).…”

Physiological adaptations and ovarian cyclicity of Holstein and Montbéliarde cows under two low-input production systems

“…A more positive energy balance is further supported by the greater milk protein content and yield observed in SEMI, because energy balance is a major nutritional determinant of milk protein synthesis (DePeters and Cant, 1992). Cows under SEMI had increased milk fat concentration and secretion of trans-10 18:1, an indicator of altered rumen FA biohydrogenation with starch and polyunsaturated fatty acid (PUFA)-rich diets (Chilliard et al, 2007). Increased trans-10 18:1 probably results from interactions of concentrate feeding with basal diet, pasturing young grass that is potentially rich in fermentable sugars and PUFAs, and eventual problems of concentrate allocation to individual cows owing to group feeding, as suggested by the individual variability of trans-10 18:1 profiles.…”