Feeding dairy cows with full fat extruded or toasted soybean seeds as replacement of soybean meal and effects on milk yield, fatty acid profile and CLA content

Abstract

The aim of this study was to evaluate the effects of the replacement of about 70% of soybean meal (SBM) with extruded(ES) or toasted (TS) full-fat soybean seeds in diets for lactating cows on milk quality, fatty acid profile, and conjugatedlinoleic acid (CLA) content. Eighteen lactating cows were assigned to 3 groups which received a basal diet, supplementedwith 1.8, 2.1 and 2.1 kg/head, respectively, of SBM, ES and TS. There was no significant effect on milk yield,calculated as the difference between daily yield during the experimental period and the mean of the last 5 days of adaptation(-1.65, -1.29 and -0.20 kg/d, respectively, for SBM, ES and TS; P>0.10) and milk quality parameters (fat, protein,urea and cheese making parameters) among treatments. In the ES group there was a decrease in the short chainFA content (from C4 to C13) in milk fat (9.2 vs 11.0 and 10.8 g/100 g lipids, respectively, for ES, SBM and TS; PMedium chain FA (from C14 to C17) content in milk fat was lower for ES and TS groups compared with SBM (46.8 and48.0 vs 54.8 g/100 g lipids respectively; PSBM group compared to the others (34.3 vs 44.2 and 41.2 g/100 g lipids, respectively, for SBM, ES and TS; PThe replacement of SBM with ES enhanced oleic and linoleic acid and, particularly, CLA content. Intermediate values wereobserved for the TS group. CLA content (0.91, 0.62 and 0.56 g/100 g lipids, respectively, for ES, TS and SBM; Pincreased throughout the trial in all groups. ES also reduced the proportion of SFA with respect to SBM (65.2, 68.2 and70.9 g/100 g lipids, respectively, for ES, TS and SBM; Pin the same order; Pimproving the health-quality of milk. The various soybean products did not affect either metabolic profile (protein, urea,glucose, cholesterol, NEFA, triglycerides, liver parameters and mineral serum content) or rumen parameters (pH, ammoniaand VFAs). The replacement of SBM with ES and TS permitted an improvement in the nutritional properties of milkwithout negatively affecting animal performances.

Keywords

• Dairy cows, Soybean sources, Milk, Fatty acid profile, Conjugated linoleic acids (CLA)