Many aspects of transporting slaughter horses will be federally
regulated in the near future. The development of these regulations may
be a model for other animal agriculture welfare issues. The media has a
strong input in formulating the public's perception of different animal
welfare issues that will continue to garner the attention of
legislators. Animal protection organizations will link their ability to
lobby either state or federal policy makers with the public's concern to
initiate and establish regulations. Since there is a dearth of
scientific studies examining many of the agricultural animal well-being
issues, government agencies may provide resources for research to gather
objective data in developing and proposing regulations. Regulations
based on science may be advantageous both to the animals and as a basis
of trade negotiations, thus benefiting the economics of the industry.
One of the interesting comparisons between studies of horses transported
under hot, humid conditions was that the recreational horses transported
individually, cross-tied in a commercial van responded with greater
cortisol concentrations and neutrophil to lymphocyte ratios than the
slaughter horses hauled loose in groups for similar duration (Table
1). The van horses were healthy, fit riding horses, and had previous
long-term hauling experience. Compared with the slaughter horses, these
horses were subjected to the normal feeding and exercise schedule prior to
transport, whereas the slaughter horses were mixed in unfamiliar groups,
some were led or ridden through the auction arena, and their feeding
schedule was intermittent. One of the major differences between the
transport conditions of the slaughter and riding horses was that the
slaughter horses were hauled loose in groups with no head restriction;
whereas, the riding horses were shipped individually with their head and
neck movement restricted by the cross-ties.
The objective of current studies is to compare the physiological responses
of loose versus cross-tied horses during 24 hours of road transport under
similar summer conditions as the previous studies. Ten horses were used
in two trials in a cross-over design and transported in a commercial
van. In the first trial, six horses were cross-tied in individual
compartments, while two pairs of horses were loose in separate
compartments. In the second trial, the treatments were reversed. Floor
area per horse was similar between treatments. Preliminary results are
also shown in Table 1. The stress indices of cortisol and N:L ratio
showed elevated responses at the post-transit blood collection as compared
to the pre-transit sampling in both the loose and cross-tied horses. The
magnitude of elevation of these stress indices in the loose horses
traveling in the van was similar to the slaughter horses of similar
duration, and the mean values for the cross-tied horses were similar to
the previous study of horses transported cross-tied in a van (19). Thus,
head restriction appears to further elevate the response of these stress
indices, even under the conditions and handling commonly used for the
professional transport of high quality horses. Additionally, the
perception that cross-tying horses in a commercial horse van provides
comparably low stress transportation under road conditions could be
improved by allowing head and neck movement, as demonstrated by the
slaughter horse transport industry.
Table 1. Comparison of mean pre- and post-transport values for cortisol,
neutrophil to lymphocyte (N:L) ratio, and white blood cell (WBC) counts
from horses evaluated on three separate transport studies.
Cortisol, ng/mlN:L ratioWBC, x 103/L
Slaughter horses,1 loose
16-23 h, (n=85)45 to 623.3 to 3.811 to 12
27-30 h, (n=144)44 to 513.3 to 4.911 to 13
Riding horses,2 24 h, van
Cross-tied (n=15)40 to 1013.0 to 7.58 to 13
Riding horses,3 24 h, van
Cross-tied (n=10)43 to 1002.7 to 128 to 16
Loose (n=10)41 to 672.7 to 5.99 to 11
1 Reference: Stull, 1999.
2 Reference: Stull and Rodiek, In-Press.
3 Reference: Stull and Rodiek, 2000.
Carolyn L. Stull, MS, PhD
Extension Specialist
Animal Welfare Program
Veterinary Medicine Extension
One Shields Avenue
University of California
Davis, CA 95616
(530)-752-0855 Phone
(530)-752-7563 Fax