Abstract #127
Section: Small Ruminant (orals)
Session: Small Ruminant Platform Session: Addressing Management Challenges and Improving Performance in Small Ruminants
Format: Oral
Day/Time: Monday 11:15 AM–11:30 AM
Location: Room 301 A
Session: Small Ruminant Platform Session: Addressing Management Challenges and Improving Performance in Small Ruminants
Format: Oral
Day/Time: Monday 11:15 AM–11:30 AM
Location: Room 301 A
# 127
Thermophysiological traits within a flock of dairy ewes and variability in the response to a heat stress challenge.
Abdelaali Elhadi*1, Gerardo Caja1, 1Universitat Autonoma de Barcelona, Bellaterra, Barcelona, Spain.
Key Words: heat stress, dairy sheep, temperature
Thermophysiological traits within a flock of dairy ewes and variability in the response to a heat stress challenge.
Abdelaali Elhadi*1, Gerardo Caja1, 1Universitat Autonoma de Barcelona, Bellaterra, Barcelona, Spain.
The response to a short-term heat stress (HS) challenge was studied in a flock of Manchega dairy ewes (n = 100). Ewe classes and features (n; BW; BCS) were hoggets (12; 33.9 ± 1.1 kg; 2.98 ± 0.01), dry (14; 55.1 ± 2.1 kg; 2.98 ± 0.16) and lactating (74; 75.6 ± 1.0 kg; 3.64 ± 0.04). All the ewes were open. Lactating ewes (162 ± 15 DIM; 1.07 ± 0.05 L/d) were machine milked × 1-daily. Flock was fed a TMR ad libitum. On the afternoon of the previous HS challenge day, ewes were moved in groups of 20 to 24 to a heat-temperature controlled shelter (Trivic, ES) and randomly allocated in groups of 4 ewes on sawdust-bedded pens at thermoneutral conditions (TN, 17.7°C and 71%RH; THINRC = 63). Feed and water were ad libitum. On the morning of the challenge day, thermophysiological traits consisting of rectal temperature (RT; AccuVet digital, TW), infrared skin temperature (ST; Optris MS Plus infrared, DE) and respiratory rate (RR, 2 operators by sight) were recorded. After fed and water removal, the shelter was switched to HS (35.6°C and 43%RH; THINRC = 84) in 30 min and these conditions maintained for 150 min. Thermophysio traits were again recorded after 2 h at HS. Data were treated using the PROCMIXED of SAS (v.9.4). RT varied by class, hoggets showed higher values than adult ewes under TN (39.29 ± 0.08 vs. 39.02 ± 0.04°C; P < 0.001) and HS (39.57 ± 0.07 vs. 39.28 ± 0.05°C; P < 0.001) conditions. No differences were detected in ST by class, which values depended on ambient conditions (TN vs. HS, 35.67 ± 0.08 vs. 37.73 ± 0.43°C; P = 0.60 to 0.12). RR was the most affected trait by class and challenge. All ewe classes showed similar RR under TN (38 ± 1 breaths/min; P = 0.21), but lactating ewes showed lower RR than dry and hoggets (99 ± 3 vs. 122 ± 7 breaths/min; P < 0.001) under HS, the last not differing between them. RR and RT responses showed normal distributions and wide ranges, suggesting interest for selection. Most sensitive classes to HS were hoggets and dry ewes, the lactating ewes being able dissipate better their body heat. Study supported by MINECO Spain (Project RTA2015-0035-CO3-02).
Key Words: heat stress, dairy sheep, temperature
