Riera Blanco, Ashley N.
Collections
1 results
Publication Search Results
Now showing 1 - 1 of 1
Publication Restricted Histological characteristics of skin from Puerto Rican slick-hair and wild type Holstein cows(2017) Riera Blanco, Ashley N.; Jiménez Cabán, Esbal; College of Agricultural Sciences; Pagán Morales, Melvin; Sánchez Rodríguez, Héctor L.; Department of Animal Science; Pagán Parés, OmellIn Puerto Rico (PR), certain Holstein cattle had for some time been phenotypically identified with shorter than normal hair. Later it was learned that this variant in hair length and morphology is due to a cytosine deletion in exon 10 of the prolactin receptor gene. Presently, the term slick hair (SH) cattle is in common use for animals with this short hair genotype. SH cows from countries such as Venezuela (Carora) and the United States (Holstein x Senepol) have shown better thermotolerance in tropical climates due to this genotype. These cows demonstrated higher sweating and lower respiration rates than wild type (WT) Holstein cows. SH Holstein cows from Puerto Rico were found to have lower vaginal temperatures that could lead to better reproductive function when compared to WT. The higher thermotolerance capacity of SH cows may involve differences in skin anatomy associated with the heat dissipation process. Therefore, the objective of the present investigation was to determine if histological differences exist between the skin of SH and WT Puerto Rican Holstein cows. Twenty-nine previously genotyped animals were used; fourteen WT and fifteen SH were evaluated. A skin biopsy (3.5mm diameter) was obtained from the rump of each cow. Tissues were fixed and embedded in paraffin, then sectioned at 5μm. One slide of each sample was stained with hematoxylin and eosin, and another slide was treated with a blood vessel (BV) staining kit. The slides were visualized under a microscope at a magnification of 45x and a digital picture was obtained. An area of 2,800 μm2 was selected in these images to calculate the quantity, width and percentage of area covered by cross-sectional cuts of sweat glands (SwG), sebaceous glands (SbG) and BV, using ImageJ Software (National Institutes of Health, Bethesda, Maryland, USA). The percentage of area covered by SwG was greater (p=0.03) in the skin of SH than in WT cows (6.3 ± 0.5% vs. 4.7 ± 0.5%), were as the percentages of area covered by SbG and BV were similar for respective SH and WT animals (3.7 ± 0.4% vs. 3.2 ± 0.4%; 1.2 ± 0.2% vs. 1.1 ± 0.2%). Furthermore, the width of SwG was greater (p=0.01) in the skin of SH when compared to WT Holstein cows (90.2 ± 3.6 μm vs. 77.6 ± 3.5 μm). In addition, the width of SbG was greater (p=0.05) on the skin of the SH than in the WT cows (101.5 ± 5.2μm vs. 86.9 ± 5.0 μm). However, cows of the two genotypes did not differ (p>0.05) in the number of SwG, SbG and BV present in the examined area: (15.7 ± 1.8 vs. 16.6 ± 1.8; 10.0 ± 1.1 vs. 10.6 ± 0.9; and 2.4 ± 0.5 vs. 3.2 ± 0.4, respectively). The present results demonstrated that SH cows have a greater percentage of skin area covered by SwG, and possess wider SwG and SbG which may represent a morphological adaptation for better thermotolerance.