Dietary Soybeans Extruded at Different Temperatures: Milk Composition and In Situ Fatty Acid Reactions

Abstract

Twenty-four multiparous Holstein cows, 4 of which were ruminally fistulated, were assigned to one of four diets containing full-fat soybeans, either raw or extruded at 120, 130, or 140 degrees C. Our hypothesis was that the extrusion of full-fat soybeans, as well as the extrusion temperature, would affect the bypass of fatty acids in the rumen and, thus, would modify the fatty acid profile of milk fat. Total mixed diets containing 23.7% soybeans (percentage of DM) were fed for 8 wk. Milk yield was lower, and the proportion of milk CP was higher, for cows fed raw soybeans than for cows fed extruded soybeans. Compared with raw soybeans, extruded soybeans increased the concentration of delta-11-trans-C18:1 from 2.72 to 11.41% in milk fat but had no effect on yield or percentage of milk fat. Polyunsaturated fatty acids of raw soybeans disappeared more rapidly than did those of extruded soybeans from bags incubated in the rumen of fistulated cows. However, more delta-11-trans-C18:1 and C18:0 appeared in bags containing extruded soybeans than in bags containing raw soybeans. Extrusion of full-fat soybeans influenced the metabolism of fatty acids in the rumen and the fatty acid profile of milk fat, but the temperature of extrusion had only minor effects on these parameters.

Conjugated linolenic acid (CLnA), conjugated linoleic acid (CLA) and other biohydrogenation intermediates in plasma and milk fat of cows fed raw or extruded linseed

“…With raw linseed, Gonthier et al (2005) reported a 38% decrease of 8:0-14:0 daily output, and a 34% decrease was observed due to linseed oil (Loor et al, 2005). Similar effect was observed after soybean (Chouinard et al, 1997) or sunflower (Schingoethe et al, 1996) dietary addition. Milk FA from 6:0 to 14:0 and part of 16:0 are synthesised by the mammary gland, and increasing amounts of unsaturated fat supplement are known to inhibit the synthesis of these FA (Clapperton and Banks, 1985).…”

“…The relative increase in milk was over 40% for trans-6 to trans-11 18:1 and cis-15 18:1, but was only 18% for trans-15 18:1, and around 10% for trans-12 and trans-16 18:1. Extrusion of oilseeds is known to result in increased proportions of trans intermediates in milk fat (Chouinard et al, 1997;Chouinard et al, 2001) but our results show that the effects differ according to the trans-18:1 isomer, suggesting that extrusion affects the pathways of ruminal BH.…”

“…The discrepancy between our results and theirs could be attributed to the difference of the extrusion temperature of linseed, which was 1558C in their experiment compared with 1208C in our experiment. However, Chouinard et al (1997) demonstrated using soya beans that increasing extrusion temperature from 120 to 1408C has only minor effects on milk PUFA.…”

Fatty acids in forages. I. Factors affecting concentrations

“…In the present study, the concentration of C18:3 was higher in silage than in fresh grass. No trans isomers of C18:2 or C18:1 were detected in silage, even though the method used allowed the detection of these fatty acids (Chouinard et al 1997), which indicates a low rate of unsaturated FA biohydrogenation during silage fermentation.…”

Phytoestrogens in bovine plasma and milk - LC-MS/MS analysis

“…Soy, a common component of dairy cattle diet, is a rich source of energy due to its high contents of proteins and oil (Chouinard et al 1997). In addition to these important nutrients, soy-based Figure 3.…”