Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS

1 st WorkshopXIII International Feed Technology Symposiumbut influenced on reducing of glucose concentration, and increasing of ureaconcentration in serum, and numerical decreasing of milk and milk protein yield(Plaizier, 2004).Using of alfalfa haylage instead of raygrass haylage in diets for dairy cows in the secondphase of lactation, increasing BW gain, (0.48 kg/day), and yields of milk (6.1 kg/day),4% FCM (6.8 kg/day), milk fat (0.26 kg/day), milk protein (0.25 kg/day). Feedconversion (kg of milk/kg consumed DM) and conversion of consumed N (g milk N /gconsumed N) were greater for cows fed raygrass haylage (27 %), as digestibility ofdietary DM (16 %), NDF and ADF (53 %) too (Broderick et al. 2002). Raygrass andgrass generally are characterized with higher digestibility of DM, NDF and ADF, thanalfalfa, but with slower rate of degradation. Decreasing of dietary DM digestibility thatis related with increased intake is more expressive for grass than for legumes.Replacing of one half of corn silage with alfalfa haylage in ration for dairy cows in thesecond phase of lactation, increases percentage of milk fat (2.68 and 3.32%), and milkfat yield (1.17 and 1.45 kg/day). There were no differences for DM intake, and dailymilk production, between treatments (Onetti et al. 2004). Replacing of one-half of alfalfahaylage with corn silage, decreases milk fat content from 3.35 to 3.04 %. Ruminalpropionate concentration was higher, with decreasing chop length of forages, as alsowith replacing a part of alfalfa haylage with corn silage (probably because of increasingquantity of starch in ration). Acetate to propionate ratio was lower for diets with shorterforage feed particles, as also when alfalfa haylage were replaced with corn silage(Krause and Combs 2003).According to Ferreira and Mertens (2005), DM digestibility of ground corn silage firstdepends of NDF and ADL (lignin insoluble in acid detergent) content (R 2 =0.80). In vitrodigestibility of corn silage DM that is not additionally ground depends of ADL content,portion of kernel particles larger than 4.75 mm, mean particle size of silage and DMcontent. Additional processing of kernel, treating chopped whole corn plant withonboard kernel processing rolls, increasing starch digestibility of silage. Cooke andBernard (2005) report decreasing of corn silage starch digestibility for lactating cows,with increasing apart between kernel processing rolls from 2 mm to 8 mm. Cows in thesecond phase of lactation fed total mixed ration based on corn silage with theoreticalchop length of 27.8 mm, consumed more DM (25.55 and 24.55 kg), OM (23.85 and 22.9kg), showed higher ruminal (64.7 and 58.2 %) and total (96.65 and 96.0) starchdigestibility, lesser daily yield of milk fat (1.21 and 1.32 kg), higher ruminalconcentration of acetate (58.3 and 58.05 mg/dl) and lower concentration of propionate(25.85 and 26.3 mg/dl), greater intake of NE L (171.33 and 163.18 MJ/day), than cowsfed silage with theoretical cut length of 39.7 mm (Johnson et al. 2003). Kernelprocessing increased dietary starch digestibility (96.8 and 95.85 %). Additional kernelprocessing increased DM intake, milk yield and milk fat percentage (Bal et al. 2000).Authors explained these by higher ruminal and total starch digestibility. Decreasing ofchop length of corn silage (1.90 and 0.95 cm) caused a depression of fiber digestibility.Digestibility of DM, starch and crude protein, were significant greater for cows fedrations based on corn silage with 32 % of DM content, compared with silage with 40 %of DM. Crop maturity and DM content of whole corn plant at the moment of ensiling,influenced at greater extent on fermentation and quality of silage, compared withadditional kernel processing and using of inoculants. Increasing DM content of corn221