title: Effects of forage type, forage to concentrate ratio, and crushed linseed supplementation on milk fatty acid profile in lactating dairy cows.
abstract: The effects of an increasing proportion of crushed linseed (CL) in combination with varying forage type (grass or corn silage) and forage to concentrate ratio (F:C), and their interactions on milk fatty acid (FA) profile of high-producing dairy cows was studied using a 3-factor Box-Behnken design. Sixteen Holstein and 20 Swedish Red cows were blocked according to breed, parity, and milk yield, and randomly assigned to 4 groups. Groups were fed different treatment diets formulated from combinations of the 3 main factors each containing 3 levels. Forage type (fraction of total forage dry matter, DM) included 20, 50, and 80% grass silage, with the remainder being corn silage. The F:C (DM basis) were 35:65, 50:50, and 65:35, and CL was supplied at 1, 3, and 5% of diet DM. Starch and neutral detergent fiber content (DM basis) of the treatment diets ranged from 117 to 209 g/kg and 311 to 388 g/kg, respectively. Thirteen treatment diets were formulated according to the Box-Behnken design. During 4 experimental periods of 21 d each, all treatment diets were fed, including a repetition of the center point treatment (50% grass silage, 50:50F:C, 3% CL) during every period. Intake, production performance, and milk FA profile were measured, and response surface equations were derived for these variables. Shifting from 80% grass silage to 80% corn silage in the diet linearly increased dry matter intake (DMI), net energy for lactation (NE(L)) intake, cis-9,cis-12-C18:2 (C18:2n-6) intake, and milk yield, and linearly decreased cis-9,cis-12,cis-15-C18:3 (C18:3n-3) intake and milk fat content. Shifting from a high forage to a high concentrate diet linearly increased DMI, NE(L) intake, C18:2n-6 intake, and milk yield, and decreased milk fat content. Supplementation of CL linearly increased C18:3n-3 intake, but had no effect on DMI, NE(L) intake, milk yield, or milk fat content. Shifting from 80% grass silage to 80% corn silage linearly increased proportions of trans-10-C18:1 and C18:2n-6 in milk fat, whereas the proportions of trans-11,cis-15-C18:2 and C18:3n-3 linearly decreased. Significant interactions between CL supplementation and F:C were found for proportions of trans-10-C18:1, trans-15-C18:1, cis-15-C18:1, trans-11,cis-15-C18:2, and C18:3n-3 in milk fat, with the highest levels achieved when the diet contained 5% CL and a 35:65F:C ratio. The effect of supplementing CL on several milk FA proportions, including C18:2n-6 and C18:3n-3, depends significantly on the F:C ratio and forage type in the basal diet.
authors: Animal Nutrition Group, Wageningen University, Marijkeweg 40, 6709 PG Wageningen, the Netherlands. attje-rieke.sterk@wur.nl
authors: A
authors: A
authors: Sterk
authors: B E O
authors: BE
authors: Johansson
authors: H Z H
authors: HZ
authors: Taweel
authors: M
authors: M
authors: Murphy
authors: A M
authors: AM
authors: van Vuuren
authors: W H
authors: WH
authors: Hendriks
authors: J
authors: J
authors: Dijkstra
mesh_terms: D000818:Animals; D002417:Cattle; D019587:Dietary Supplements; D004435:Eating; D005227:Fatty Acids / Q000032:analysis*; D005260:Female; D019597:Flax; D007774:Lactation / Q000187:drug effects; D008892:Milk / Q000737:chemistry* / Q000187:drug effects; D006109:Poaceae; D012820:Silage / Q000032:analysis; D003313:Zea mays
chemical_list: D005227:Fatty Acids