Abstract #M202

# M202
Slick-haired Puerto Rican Holstein cows have larger sweat glands than their wild type-haired counterparts.
Z. E. Contreras-Correa*1, N. Peña-Alvarado2, W. Torres-Ruiz2, J. R. Almodóvar-Rivera3, K. I. Domenech-Pérez1, C. Youngblood4, M. Pagán-Morales1, A. Mesonero-Morales1, J. Curbelo-Rodríguez1, P. F. Randel-Follin1, G. C. Muñiz-Colón1, V. Colón-González1, Á. L. Jiménez-Arroyo1, G. M. Jiménez-Arroyo1, H. L. Sánchez-Rodríguez1, 1University of Puerto Rico at Mayaguez Campus, Department of Animal Science, Mayaguez, Puerto Rico, 2Laboratorio de Investigaciones Pesqueras, Departamento de Recursos Naturales y Ambientales, Cabo Rojo, Puerto Rico, 3University of Puerto Rico at Mayaguez Campus, Department of Biology, Mayaguez, Puerto Rico, 4Institute of Genomics, Biocomputing and Biotechnology, Mississippi State University, Mississippi State, MS.

In the Puerto Rican Holstein cow population, the presence of a shorter and sleek hair coat (SLICK) has previously been associated with a superior tolerance to heat stress in terms of lower body temperature and respiratory rate, and a greater milk yield in comparison with wild type-haired (WT) cattle. However, besides a shorter hair coat, this superior thermoregulatory capacity must be of a multifactorial nature. Therefore, the present study aimed to evaluate other factors that may help to better understand these differences, including skin thickness (ST; from the epidermis to the deep layer of the dermis), and cross-sectional sweat gland area (SGA) and perimeter (SGP). Groups of SLICK (n = 7) and WT (n = 7) cows with similar milk yields (P = 0.8025), were first phenotypically selected and then genomically confirmed. From each cow, 2 skin biopsies (6 mm in diameter) were collected immediately cranial to the right shoulder after local anesthesia infiltration. Samples were fixed in 10% formalin, embedded in paraffin, sectioned perpendicular to the skin surface (7 µm thickness), and stained with hematoxylin and eosin. From each biopsy, one microscopic slide was prepared containing 3 histological sections. Microscopic images (4×) were analyzed by the NIS Element D software (Nikon, Melville, NY), evaluating all the cross-sectional cuts of sweat glands per histological section (39.01 ± 11.97 cuts / section) for SGA and SGP determination. The ST was measured in triplicate from each histological section. Data were averaged by microscopic slide (PROC MEANS) and analyzed using the GLIMMIX procedure of SAS. The SLICK cows presented greater values of ST (1,006 ± 34 vs. 808 ± 23 µm; P = 0.0027), SGA (6,009 ± 335 vs. 3,169 ± 306 µm2; P = 0.0008), and SGP (315 ± 9 vs. 232 ± 12 µm; P = 0.0024) than their WT counterparts. Our results demonstrate a greater size of the sweat glands in the shoulder region of the SLICK cows. Future studies should evaluate if such differences are associated with increased sweat secretion, thus facilitating body heat dissipation through evaporation.

Key Words: slick-haired Puerto Rican Holstein cow, sweat glands, thermoregulation