Abstract #42
Section: ADSA Southern Section Oral Competition (Graduate)
Session: ADSA Southern Section Graduate Student Oral Competition
Format: Oral
Day/Time: Monday 11:00 AM–11:15 AM
Location: 318
Session: ADSA Southern Section Graduate Student Oral Competition
Format: Oral
Day/Time: Monday 11:00 AM–11:15 AM
Location: 318
# 42
Comparing summer to winter ratios of milk production and SCS among states in the southeast United States.
J. Guinn*1, D. Nolan1, P. Krawczel2, C. Petersson-Wolfe3, G. Pighetti2, A. Stone1,4, S. Ward4,5, J. Bewley1, 1University of Kentucky, Lexington, KY, 2University of Tennessee, Knoxville, TN, 3Virginia Polytechnic Institute and State University, Blacksburg, VA, 4Mississippi State University, Starkville, MS, 5North Carolina State University, Raleigh, NC.
Key Words: summer:winter ratio, heat stress, milk production
Comparing summer to winter ratios of milk production and SCS among states in the southeast United States.
J. Guinn*1, D. Nolan1, P. Krawczel2, C. Petersson-Wolfe3, G. Pighetti2, A. Stone1,4, S. Ward4,5, J. Bewley1, 1University of Kentucky, Lexington, KY, 2University of Tennessee, Knoxville, TN, 3Virginia Polytechnic Institute and State University, Blacksburg, VA, 4Mississippi State University, Starkville, MS, 5North Carolina State University, Raleigh, NC.
The southeastern United States experiences hot, humid summers causing heat stress, resulting in reduced milk production and milk quality. The objective was to compare summer:winter ratios for milk production and somatic cell score (SCS) among states in the Southeast United States. Data from DHIA were collected from 2007 to 2016 for herds in Florida (n = 91), Georgia (n = 205), Kentucky (n = 413), Mississippi (n = 47), Tennessee (n = 183), and Virginia (n = 479). The summer:winter ratio was developed as a metric to estimate alleviation of heat stress by cow cooling strategies. This study used the ratios to compare milk production or SCS in summer (June 21-September 21; numerator) vs. winter (December 21-March 19; denominator) using test day averages for herds within state. The underlying assumption is that the closer the ratio is to one, the less heat stress is experienced by the cows within the herd. The GLM procedure of SAS 9.3 (SAS Institute, Inc., Cary, NC) was used to analyze the lsmeans of milk production and SCS summer:winter averages and ratios for herds within state. Results are shown in Table 1. Results show that the milk production summer:winter ratio is highest for Virginia, and lowest for Mississippi, indicating that cows in Virginia herds experience less heat stress. Ratios for SCS indicate that cows in Florida herds experience the most heat stress in the summer. The summer:winter ratios could be widely available for producers and consultants as a tool to assess on-farm heat abatement and encourage improvement in their cow cooling strategies. Further analyses will investigate effects of cow cooling strategies specific to herds in this region in relation to THI, on summer:winter ratios.
Table 1.
| State | Summer | Winter | S:W ratio |
| Test-day milk yield | |||
| Florida | 56.28 | 63.37 | 0.88 ± 0.13cd |
| Georgia | 55.88 | 63.69 | 0.88 ± 0.008d |
| Kentucky | 57.93 | 64.73 | 0.91 ± 0.006bc |
| Mississippi | 52.52 | 62.41 | 0.87 ± 0.02cd |
| Tennessee | 58.08 | 63.30 | 0.93 ± 0.009b |
| Virginia | 66.34 | 69.16 | 0.96 ± 0.005a |
| Test-day SCS | |||
| Florida | 3.48 | 3.03 | 1.14 ± 0.03a |
| Georgia | 3.20 | 3.10 | 1.05 ± 0.01ab |
| Kentucky | 2.98 | 2.92 | 1.06 ± 0.01b |
| Mississippi | 3.44 | 3.12 | 1.10 ± 0.03ab |
| Tennessee | 3.18 | 3.04 | 1.07 ± 0.02ab |
| Virginia | 2.95 | 2.80 | 1.07 ± 0.009ab |
Key Words: summer:winter ratio, heat stress, milk production
