Abstract
Anecdotally, wild type (WT) Puerto Rican Holstein cows perform poorly in hot weather compared with their short-haired (SLICK) counterparts, but scientific evidence supporting this claim is limited. Thus, comparisons of their vaginal temperature (VT), sweat gland size (SGS) and milk production (MP) values were made. Data were analyzed by Proc GLIMMIX and REG (SAS). During the cool season (March 2014) VT was similar in WT and SLICK cows (38.71±0.09 and 38.71±0.08 °C, respectively; P=0.9634). However, in the intermediate air temperatures (AT) season (April 2014), WT cows presented VT values 0.25° C higher than their SLICK counterparts from 1900-2100h (P=0.0213). Moreover, in the hot season (August 2015) VT was greater in WT than in SLICK cows by 0.31° C from 1800-0700h and 0900-1600h (P=0.0032), and by 0.20° C at 0800h (P=0.0584) and 1700h (P=0.0619). The VT increased linearly until AT reached 30.5° C in both WT (0.10° C per 1° C of AT; P<0.0001) and SLICK cows (0.08° C per 1° C of AT; P<0.0001). After 30.5° C, no further VT-AT relationship was observed. The WT had smaller SGS (232±12 vs. 315±9 μm perimeter; P=0.0024) and smaller MP (17.11±0.63 vs. 20.26±1.28 kg/d; P=0.0288) than the SLICK cows. The SLICK cows demonstrated superior thermoregulatory capacity, which seems to depend directly on the severity of the AT.
Highlights
IntroductionPuerto Rico’s tropical weather is characterized by chronically elevated air temperature (AT) and humidity (Daly et al, 2003)
Puerto Rico’s tropical weather is characterized by chronically elevated air temperature (AT) and humidity (Daly et al, 2003). In cattle, such environmental conditions are known to result in heat stress, which negatively impacts feed intake, milk production (Kadzere et al, 2002; West, 2003) and reproduction (Jordan, 2003)
No differences in vaginal temperature (VT) were observed between wild type (WT) and SLICK cows (38.71±0.09 and 38.71±0.08 °C, respectively; P=0.9634)
Summary
Puerto Rico’s tropical weather is characterized by chronically elevated air temperature (AT) and humidity (Daly et al, 2003) In cattle, such environmental conditions are known to result in heat stress, which negatively impacts feed intake, milk production (Kadzere et al, 2002; West, 2003) and reproduction (Jordan, 2003). Besides the wild type-haired cows (WT; with long and dense hair coats), a short and sleek-haired phenotype (SLICK) exists among Puerto Rico’s dairy cattle. These SLICK cattle originated from crossbreeding the Puerto Rican Criollo cows with improved dairy genetics beginning in the 1950s (Sánchez-Rodriguez, 2019). These Criollo cows had the short-haired phenotype (Sánchez-Rodriguez, 2019), which is believed to be a dominant trait (Olson et al, 2003), allowing this characteristic to be inherited until today in a portion of Puerto Rico’s
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