Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 4/10/2012
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Previous research suggested that crude protein (CP) from canola meal (CM) was used more efficiently that CP from solvent soybean meal (SBM) by lactating dairy cows. We wished to test whether CM was more effective than SBM on low CP (14.9% CP) than high CP (16.8% CP) diets and to see if it was advantageous to supplement with rumen-protected methionine (Met) plus lysine (Lys) (RPML). Fifty lactating Holstein cows were blocked by days-in-milk and parity into 10 squares in a replicated 5 x 5 Latin square trial. Five squares were fed: 1) low CP + SBM, 2) low CP + CM, 3) low CP + SBM and CM, 4) high CP + SBM, and 5) high CP + CM; the other 5 squares were fed the same diets except with added RPML (20 g/d of Met and 69 g/d of Lys). Diets contained (dry matter basis): 40% corn silage, 26% alfalfa silage, 13-23% corn grain, 2.4% mineral-vitamin premix and 31-33% NDF. Diets were administered in five 3-wk periods. Data from the last wk were analyzed using Proc Mixed in SAS. There were no significant effects of RPML in this trial (P = 0.11). Dietary CP (diets 4 and 5 vs. 1 and 2) increased fat yield and greatly elevated milk urea nitrogen (MUN). Relative to SBM, feeding CM increased dry matter intake (DMI), and yield of milk and true protein, and depressed MUN. At 14.9% CP, there was a similar response in DMI and weight gain on CM and SBM + CM vs. SBM. In this trial, replacing SBM with CM resulted in improved production and N efficiency at both 14.9 and 16.8% CP.