|DE Veth, Michael -|
|Luchini, N -|
Submitted to: Journal Dairy Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: February 26, 2011
Publication Date: July 11, 2011
Citation: Broderick, G.A., Walgenbach, R.P., De Veth, M.J., Luchini, N.D. 2011. Supplementing rumen-protected Met and Lys in alfalfa and red clover silage diets fed to lactating dairy cows. Journal of Dairy Science. 94(E-Supplement 1):116. Technical Abstract: The action of polyphenol oxidase reduces NPN formation in red clover silage (RCS). In seven previous trials, RCS averaged (% of total N) 36% NPN vs. 54% NPN in alfalfa silage (AS). Feeding RCS has been found to increase intestinal protein absorption but with no improvement in N utilization, suggesting depressed utilization of one or more essential amino acids (AA). This trial assessed effects of adding rumen-protected Mepron® (Met [RPM]) and Lys (RPL) to AS and RCS diets. Forty-eight lactating Holstein cows were blocked by DIM and parity into 6 squares in an incomplete 8x8 Latin square with a 2x2x2 arrangement of diets: AS or RCS, with or without RPM (9 g/d of metabolizable Met) and with or without RPL (27 g/d of metabolizable Lys as AminoShureL®). Diets were formulated to contain (DM basis) 50% AS plus 20% corn silage or 63% RCS plus 7% corn silage, 24% corn, 3% solvent soybean meal, 16% CP, and 31% NDF. Periods were 4 weeks long (total: 16 weeks), and data from the last 2 weeks were analyzed using Proc mixed in SAS. AS increased (P = 0.04) DMI, yield of 3.5% FCM, milk fat content and yield, and protein content. However, RCS improved (P < 0.01) milk/DMI and MUN. Responses to RPM were not different (P = 0.07) between silages. There was greater response (P = 0.05) in DMI and milk protein content, but lower response (P = 0.02) in milk/DMI, to RPL on RCS than AS. The effect on milk protein content suggests possible impairment in Lys utilization on RCS.