02364naa a2200241 a 450000100080000000500110000800800410001902400420006010000200010224502070012226000090032952015010033865000290183965000210186865000250188970000220191470000210193670000220195770000210197970000190200070000170201977300860203621118182024-02-06       2019    bl uuuu     u00u1 u    #d7 a10.5433/1679-0359.2019v40n5p20272DOI1 aLOPES, F. C. F.  aButter fatty acid composition as a function of soybean oil supplementation and time of milking, and performance of Holstein x Gyr cows fed with chopped elephant grass-based diets.h[electronic resource]  c2019  aThe aim of this study was to evaluate the performance of cows fed with a total mixed ration composed of elephant grass and a concentrate containing 0.0% (control), 1.5%, 3.0% or 4.5% soybean oil on a dry matter basis. The effect of milking time (morning versus afternoon) on butter fatty acid composition was also evaluated. Twelve multiparous Holstein x Gyr cows with an average milk production of 18.0±4.6 kg day-1 and 90±25 days in milk were used in a triplicated 4 x 4 Latin square experimental design with 15-day periods. Data were analyzed using mixed models. There was no effect of soybean oil supplementation on dry matter or neutral detergent fiber intake (P &gt 0.05). The fat-corrected milk yield linearly decreased (P=0.0109) and the milk protein yield linearly increased (P=0.0023) in response to soybean oil supplementation. The butterfat trans-9 C18:1, cis-9 C18:1, trans-10 C18:1, trans-11 C18:1, cis-9, trans-11 CLA and trans-10, cis-12 CLA content linearly increased (P &lt 0.05), whereas the C12:0, C14:0 and C16:0 content linearly decreased (P &lt 0.001) as the level of soybean oil in the diet increased. The butter produced from afternoon milk had a lower content of C16:0 and a higher content of cis-9 C18:1 (P &lt 0.05). The supplementation of elephant grass-based-diets with soybean oil and, to a small extent, the selective segregation of milk obtained from afternoon milking sessions are strategies that can be used to improve the fatty acid composition of butterfat.  aConjugated linoleic acid  aMilk composition  aPennisetum Purpureum1 aRIBEIRO, C. G. S.1 aRODRIGUEZ, N. M.1 aGAMA, M. A. S. da1 aMORENZ, M. J. F.1 aANTONIASSI, R.1 aBIZZO, H. R.  tSemina: Ciências Agrárias, Londrinagv. 40, n. 5, p. 2027-2044, set./out. 2019.