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- Title
Effects of high heat load conditions on rectal temperature, panting score, and respiration rate of hair sheep breeds from different regions of the United States.
- Authors
Tadesse, D.; Puchala, R.; Gipson, T. A.; Portugal, I.; Sahlu, T.; Dawson, L. J.; Goetsch, A. L.
- Abstract
Thirty-seven Dorper (DOR), 35 Katahdin (KAT), and 31 St. Croix (STC) ewes (57, 58, and 44 kg [SEM 2.2]) from 45 commercial farms in the Midwest (MW), Northwest (NW), Southeast (SE), and central Texas (TX), between 2.2 and 3.4 yr of age, were used to evaluate responses to high heat load index (HLI) conditions. There were 4 sequential 2-wk periods (8 wk total) with target HLI during day/nighttime of 70/70, 85/70, 90/77, and 95/81, with weekly measures at 0700 (before increased daytime HLI), 1300, and 1700 h (preceding lower nighttime HLI). Rectal temperature (RT; °C) was affected (P = 0.003) by breed × time (38.58, 38.92, and 39.07 for DOR, 38.67, 38.92, and 39.05 for KAT, and 38.45, 38.69, and 38.85 for STC at 0700, 1300, and 1700 h, respectively [SEM 0.034]). There were interactions between week and time (P < 0.001) in respiration rate (RR; breaths/min; 52, 72, 66, and 85 at 0700 h; 120, 130, 151, and 144 at 1300 h; and 116, 123, 141, and 142 at 1700 h [SEM 3.1]) and panting score (0-4; 0.05, 0.03, 0.11, and 0.28 at 0700 h; 0.48, 0.86, 1.61, and 1.47 at 1300 h; and 0.76, 0.91, 1.54, and 1.51 at 1700 h in wk 5, 6, 7, and 8, respectively [SEM 0.042]). Breed × time RR (P = 0.008) means were 57, 107, and 103 for DOR, 55, 101, and 96 for KAT, and 47, 88, and 90 for STC at 0700, 1300, and 1700 h, respectively (SEM 3.1); however, there was an interaction (P = 0.007) among breed, region, and time (57, 110, and 101 for MW DOR; 59, 110, and 108 for MW KAT; 43, 89, and 88 for MW STC; 65, 113, and 111 for NW DOR; 54, 104, and 96 for NW KAT; 56, 92, and 94 for NW STC; 49, 93, and 96 for SE DOR; 52, 105, and 96 for SE KAT; 45, 79, and 87 for SE STC; 57, 110, and 104 for TX DOR; 54, 83, and 84 for TX KAT; and 46, 91, and 89 for TX STC at 0700, 1300, and 1700 h, respectively [SEM 6.1]). In conclusion, RT of STC was low at all times compared with DOR and KAT, even with lower RR. There appeared to be considerable adaptation from wk 1 to 2 during the 2 highest HLI periods via evening respiration. Region effects varied with breed, such as relatively high RR by STC from the NW to maintain low RT, lower RR of DOR from the SE than other regions, and a smaller difference among times in RR of KAT from TX.
- Subjects
RESPIRATION; HAIR sheep; PHYSIOLOGICAL effects of heat; PHYSIOLOGY
- Publication
Journal of Animal Science, 2017, Vol 95, p337
- ISSN
0021-8812
- Publication type
Abstract
- DOI
10.2527/asasann.2017.692