Canola meal in dairy cow diets during early lactation increases production compared to soybean meal

Abstract Text: Replacement of traditional protein sources such as soybean meal (SBM) with canola meal (CM) have resulted in increased milk yield for dairy cows in mid to late lactation. The objective was to determine performance of early lactation dairy cows fed diets formulated with CM or SBM as the main protein source at either a high (HI; 17.6%) or low (LO; 15.4%) CP concentration. Seventy-nine multiparous Holstein cows (mean ± SD; 2.76 ± 0.87 parity) received the treatment diet beginning at calving. Cows were blocked by calving date and maintained the same treatment assignment until experiment end at wk 16 of lactation. Diets were formulated to contain 39.6% corn silage, 15.4% alfalfa silage, and 45% concentrate mix on DM basis. Canola meal was included at 19.4% and 11.9% DM, whereas SBM was included at 14.5% and 8.9% DM. Data were analyzed using the MIXED procedure of SAS. BCS and BW at calving and previous lactation mature equivalent 305 were used as covariates. Cows fed CM diets were greater in milk yield compared to cows fed SBM (mean ± SEM; 55.7 vs. 51.2 ± 0.97 kg/d; P<0.01). DMI tended to be greater for cows fed CM diets (25.8 vs. 25.0 ± 0.34 kg/d; P=0.09). The source of CP did not affect milk fat, protein, lactose, or total solids percentage. Decreasing dietary CP concentration increased milk fat (4.09 vs. 3.90 ± 0.07 %; P<0.05) and total solids (12.8 vs. 12.5 ± 0.95 %; P=0.07). Cows fed HI diets produced greater milk urea N (MUN) than cows fed LO diets (12.6 vs. 9.82 ± 0.22 mg/dL; P<0.01). MUN tended to be lower for cows fed CM compared to cows fed SBM (10.9 vs. 11.4 ± 0.22 mg/dL; P=0.10). Milk fat, protein, lactose, and total solids were greater for cows fed CM in agreement with increased milk production. DMI, milk yield, milk protein percentage, and lactose percentage did not differ with varying CP concentration. Energy-corrected milk (ECM) was greater for cows fed CM compared to SBM (57.6 vs. 53.6 ± 0.95 kg/d; P<0.01). Cows fed CM exhibited a trend in feed efficiency (ECM/DMI) compared to cows fed SBM (2.27 vs. 2.16 ± 0.38; P=0.06). These data suggest milk yield and feed efficiency can be improved in early lactation with the inclusion of CM. 

Keywords: canola meal, early lactation, transition period