Abstract #M16
Section: ADSA Production MS Poster Competition (Graduate)
Session: ADSA Production Graduate Student MS Poster Competition
Format: Poster
Day/Time: Monday 7:30 AM–9:30 AM
Location: Exhibit Hall A
Session: ADSA Production Graduate Student MS Poster Competition
Format: Poster
Day/Time: Monday 7:30 AM–9:30 AM
Location: Exhibit Hall A
# M16
Effects of pasture quality on feed efficiency and production of organic dairy cows in the southeastern United States.
Hannah R. Bailey*1, David M. Butler1, Gary M. Bates1, Gina M. Pighetti1, Peter D. Krawczel1, S. Ray Smith2, Kelly Mercier2, David W. McIntosh1, Agustin G. Rius1, 1Department of Animal Science, University of Tennessee, Knoxville, TN, 2College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY.
Key Words: organic, pasture, dairy cow
Effects of pasture quality on feed efficiency and production of organic dairy cows in the southeastern United States.
Hannah R. Bailey*1, David M. Butler1, Gary M. Bates1, Gina M. Pighetti1, Peter D. Krawczel1, S. Ray Smith2, Kelly Mercier2, David W. McIntosh1, Agustin G. Rius1, 1Department of Animal Science, University of Tennessee, Knoxville, TN, 2College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY.
Empirical data on forage mixtures maximizing quality and productivity is lacking for the Southeast US. Our objective was to (1) compare production of 4 forage mixtures in the spring grazing season, and (2) evaluate forage quality on predicted milk production and feed efficiency using the Integrated Farm System Model. Mixtures contained a combination of cool and warm season legumes and/or grasses and/or brassicas with differences in legume species: (A) red clover, (B) crimson clover and cowpea, (C) alfalfa and red clover, and (D) cowpea. Mixtures were planted in 0.5-acre plots at 5 organic farms located in Kentucky and Tennessee. It was hypothesized that increased mixture diversity would increase pasture performance. Grab samples were collected from April to June 2017 to determine crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) content. Data from NIRS analysis were analyzed in SAS 9.4 using the GLIMMIX procedure. Samples ranged from 16 to 21% CP throughout the season, with mixture C having the greatest average concentration of CP at 20.4% (P = 0.03). Forage ADF ranged from 25 to 37% and NDF ranged from 45 to 51% with a lower NDF values in mixture C later in the grazing season (P = 0.09). Mean forage quality data were entered in the model and simulations mimicked 3 farm systems: (1) Holsteins on pasture for 12 h/d (H12), (2) small Holsteins on pasture for 24 h/d (SH24), and (3) Jerseys on pasture for 24 h/d (J24) during the grazing season. Simulations over 4 yr were conducted to determine predicted grazing efficiency (pasture DMI kg/milk production kg) and feed efficiency (total DMI kg/milk yield kg) on forage mixtures to achieve target milk yields (Table 1). Mixture C may help increase forage quality and productivity on organic dairies. Results predicted that use of alfalfa and red clover may help enhance forage quality and increase efficiency of grazing cows.
Table 1. Grazing efficiency (DMI kg/ milk production kg) and feed efficiency (total DMI kg/milk yield kg) per cow
| Grazing Efficiency | Feed Efficiency | ||||||
| H12 | SH24 | J24 | H12 | SH24 | J24 | ||
| A | 5.8 | 24.6 | 15.7 | 29.1 | 52.0 | 29.4 | |
| B | 5.9 | 26.5 | 15.5 | 29.1 | 54.2 | 29.2 | |
| C | 6.3 | 28.9 | 16.5 | 29.5 | 55.1 | 29.6 | |
| D | 5.9 | 24.3 | 15.5 | 29.1 | 51.9 | 29.2 | |
Key Words: organic, pasture, dairy cow
