RESUMEN
Resilience to restricted availability of drinking water was evaluated with 44 Dorper (DOR; initial age = 3.7 ± 0.34 yr), 42 Katahdin (KAT; 3.9 ± 0.36 yr), and 42 St. Croix (STC; 2.7 ± 0.29 yr) sheep from 46 farms in 4 regions of the USA (Midwest, MW; Northwest, NW; Southeast, SE; central Texas, TX). Ad libitum water intake was determined during 2 wk of period 1, with 75% of this amount offered in 2 wk of period 2 and 50% in 5 wk (i.e., 5 to 9) of period 3. Body weight and DMI in week 2 of period 1 and week 9 of period 3 were analyzed with a mixed effects model. There was a breed × period interaction (P = 0.023) in water intake relative to BW (6.17, 6.69, and 7.19 in period 1 and 3.04%, 3.26%, and 3.36% BW in period 3 for DOR, KAT, and STC, respectively; SEM = 0.219). There were 3-way interactions of breed, region, and period in BW and DMI in g/d (P < 0.010). For STC, BW was greater (P < 0.05) in period 3 vs. 1 for all regions (50.1, 47.6, 42.4, and 45.8 kg in period 1 and 51.9, 49.3, 44.5, and 47.7 kg in period 3), whereas there was only a period difference for DOR from the MW and SE (61.4, 66.0, 64.6, and 59.6 kg in period 1 and 60.6, 66.5, 65.7, and 62.4 kg) and for KAT from TX (50.1, 47.6, 42.4, and 45.8 kg in period 1 and 51.9, 49.3, 44.5, and 47.7 kg in period 3 for MW, NW, SE, and TX, respectively; SEM = 2.57). In accordance, DMI by STC was similar (P > 0.05) between periods for all regions (1.25, 1.17, 1.06, and 1.16 kg/d in period 1 and 1.12, 1.08, 1.02, and 1.02 kg/d in period 3), as was also the case for DOR from MW and SE but not from NW or TX (1.54, 1.50, 1.30, and 1.41 kg/d in period 1 and 1.41, 1.13, 1.25, and 1.18 kg/d in period 3) and KAT from TX though not from the other 3 regions (1.47, 1.52, 1.48, and 1.40 kg/d in period 1 and 1.06, 1.15, 1.30, and 1.33 kg/d in period 3 for MW, NW, SE, and TX, respectively; SEM = 0.061). In conclusion, based on BW and DMI with water intake restricted at 50% of ad libitum consumption by individual animals, STC appeared more consistent in display of high resilience to restricted water availability, although DOR from 2 regions and KAT from 1 also were relatively resilient. The results suggest benefit to breed comparisons of inclusion of animals from multiple areas and that environmental conditions of regions may have disparate effects with different breeds of hair sheep.
