Abstract #81
Section: Graduate Student Competition
Session: ADSA Production Division Graduate Student Oral Competition, MS
Format: Oral
Day/Time: Monday 9:45 AM–10:00 AM
Location: Wekiwa 6
Session: ADSA Production Division Graduate Student Oral Competition, MS
Format: Oral
Day/Time: Monday 9:45 AM–10:00 AM
Location: Wekiwa 6
# 81
Effect of nutrition and management practices on de novo fatty acid synthesis in northeastern US dairy herds.
Melissa E. Woolpert*1,2, Catarina Melilli3, Kurt W. Cotanch1, Heather M. Dann1, Rick J. Grant1, Larry E. Chase3, David M. Barbano3, 1William H. Miner Agricultural Research Institute, Chazy, NY, 2University of Vermont, Burlington, VT, 3Cornell University, Ithaca, NY.
Key Words: stocking density, milk protein, milk fat
Effect of nutrition and management practices on de novo fatty acid synthesis in northeastern US dairy herds.
Melissa E. Woolpert*1,2, Catarina Melilli3, Kurt W. Cotanch1, Heather M. Dann1, Rick J. Grant1, Larry E. Chase3, David M. Barbano3, 1William H. Miner Agricultural Research Institute, Chazy, NY, 2University of Vermont, Burlington, VT, 3Cornell University, Ithaca, NY.
This study investigated the effects of management practices and dietary chemical characteristics on de novo fatty acid (FA) concentrations in bulk tank milk from commercial dairy herds. De novo FA are synthesized primarily from rumen fermentation products acetate and butyrate. It was hypothesized that farms with higher de novo FA concentrations will prioritize management and nutrition that promote rumen health. Herds (n = 44) located in Vermont and northern New York State were selected based on high (HDN; 25.8 ± 1.0; mean ± SD) or low (LDN; 23.6 ± 0.9) de novo FA expressed as a proportion of total FA (relative %) in bulk tank milk. Management practices were assessed during one visit to each farm in March or April, 2014. Total mixed ration samples were collected and analyzed by NIR for chemical composition. Data were analyzed using the MIXED procedure of SAS with de novo group as the fixed effect, farm as the random effect, and breed as the covariate in the model. Milk (26.3 vs. 22.7 kg/d, SE = 1.3, P = 0.06), fat (1.1 vs. 0.9 kg/d, SE = 0.1, P < 0.01), true protein (0.9 vs. 0.7 kg/d, SE < 0.1, P < 0.01), and de novo FA (25.6 vs. 23.7 relative %, SE = 0.2, P < 0.01) were higher for HDN vs. LDN farms, respectively. Days in milk (170 ± 7 d; least squares means ± SE), freestall bunk space (41 ± 3 cm), manure score (2.8 ± 0.0), and freestall feeding frequency (1.5 ± 0.4 times/d) were not different between groups. However, tiestall feeding frequency (4.8 vs. 2.8 times/d, SE = 0.7, P < 0.1), freestall stocking density (1.05 vs. 1.20 cows/stall, SE = 0.06, P = 0.07), and body condition score (3.07 vs. 2.95, SE = 0.04, P < 0.01) were different between HDN vs. LDN herds, respectively. Dietary DM (40.7 ± 2.0), CP (16.0 ± 0.6%), ADF (22.9 ± 1.0%), NDF (37.5 ± 1.3%), starch (21.7 ± 1.5%), ash (8.5 ± 0.4%), and forage to concentrate ratio (1.47 ± 0.14) were not different (P > 0.12) between groups. However, dietary ether extract was lower in HDN herds (3.5 vs. 4.5%, SE = 0.2, P < 0.01). Overcrowded freestalls, reduced feeding frequency, and greater dietary ether extract content compromised de novo FA synthesis thereby decreasing milk fat and protein yields.
Key Words: stocking density, milk protein, milk fat
