Location: Dairy Forage ResearchTitle: Circulating blood metabolites in early-lactation dairy cows fed canola or soybean meals
|MOORE, SPENCER - University Of Wisconsin|
Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/11/2017
Publication Date: 6/25/2017
Citation: Moore, S., Kalscheur, K. 2017. Circulating blood metabolites in early-lactation dairy cows fed canola or soybean meals [abstract]. American Dairy Science Association Abstracts. 100(Suppl 2):111.
Technical Abstract: A successful transition from pregnancy to lactation is imperative for dairy cows to maximize milk production potential. Altering the dietary protein source can change the availability of energy to the cow. The objective of this experiment was to evaluate the effect of crude protein (CP) source canola meal (CM) or soybean meal (SBM) and CP concentration [HI (18.1%) or LO (16.2%) dry matter basis] on circulating blood metabolites. At calving, multiparous Holstein cows (n=79) were enrolled into a 2 x 2 factorial arrangement of treatments in a randomized complete block design. Cows were blocked by calving date, and the individual cow was the experimental unit. Enzymatic colorimetry was used to evaluate circulating concentrations of glucose, non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), triglycerides (TG), and plasma urea nitrogen (PUN). Serum and plasma coccygeal vein samples were collected 2 times during weeks 1, 2, 3, 4, 6, and 8 post-partum. Data were analyzed using the MIXED procedure of SAS. Body condition score (BCS) and body weight (BW) at calving were used as covariates when appropriate. Milk yield (MY) was greater for CM-fed than SBM-fed cows during wk 1-8 of lactation (mean ± SEM; 53.2 vs 49.2 ± 0.98 kg/d; P<0.001), while there was no difference in DMI (P=0.11) to support additional production. No treatment effect was observed for glucose or BHB. Circulating TG concentration was greater for cows fed CM compared to SBM-fed cows (0.13 vs 0.12 ± 0.002 mM; P=0.02). There was an interaction of source and wk for NEFA concentration (P=0.04). Efficiency of nitrogen utilization favored CM- vs. SBM-fed cows for both circulating PUN (0.37 vs 0.40 ± 0.01 mM; P=0.02) and concentration of milk urea N (MUN; 10.7 vs 11.4 ± 0.24 mg/dL; P=0.04). HI-fed cows were greater in PUN (0.44 vs 0.33 ± 0.01 mM; P<0.001) and MUN concentration (9.64 vs 12.5 ± 0.24 mg/dL; P<0.001) compared to LO-fed cows. The increase in MY can be attributed in part, to an increase in circulating TG and nitrogen utilization. However, further investigation into the CM vs. SBM milk disparity in early lactation is needed.