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Impact of Hair Coat Differences on Rectal Temperature, Skin Temperature, and Respiration Rate of Holstein x Senepol Crosses in Florida T.A. Olson, M. Avila-Chytil, C.C. Chase, Jr., P.J. Hansen and S.W. Coleman University of Florida, Gainesville; Agricultural Research Service, USDA Subtropical Agricultural Research Service Brooksville, FL Acknowledgement • Prime Rate Ranch of Okeechobee, Florida played a major role in this study by producing the 75% Holsteins (via a superovulation program) that were utilized in this study. The Slick Hair Gene • The Slick Hair gene is a single gene, dominant in mode of inheritance that is responsible for the short, shiny, hair coat of the Senepol and other breeds • Other breeds that have the Slick Hair gene include: Carora, Romosinuano, Criollo Limonero, Blanco Orejinegro, Chino Santandereano, Reyna and other criollo breeds Research Animals • The primary animals involved in this study were ¾ Holstein: ¼ Senepol yearling bulls and heifers • They were sired by two registered Holstein bulls (one red and white, one black and white) • Their dams were two Senepol X Holstein F1 cows that were paternal half sisters Research Locations • Subtropical Agricultural Research Station – Brooksville, Florida • Beef Research Unit – Gainesville, Florida Evaluations of Environmental Conditions • Relative Humidity (RH) • Ambient Temperature (AT) • Black Globe Temperature • Temperature-Humidity Index: THI = .8*AT + RH*[(AT – 14.3) + 46.3] Traits Evaluated • Rectal Temperature • Skin Temperature • Respiration Rate • Clipped Hair Weight • Growth Rate • Feed Intake Weather Conditions – STARS • Highest Ambient Temperature --- 35.5 C in June of 2000 • Temperature Humidity Index --- 103 • Lowest Ambient Temperature --- 21.0 C in February of 2000 • Temperature Humidity Index --- 73 Impact of Temperature-Humidity Index at STARS • Correlation of THI with Rectal Temperature: -0.10 (P > 0.76) in Slick Animals -0.35 (P > 0.29) in Normal-haired Animals These results are somewhat confusing but apparently indicate that the ambient conditions across the months didn’t effect rectal temperature at STARS Rectal Temperatures of Slick and Normal-Haired Holstein Crosses at STARS • September – Slick 39.4 C Normal 39.7 C P < 0.05 • October – Slick 39.3 C Normal 39.8 C P < 0.05 • November through June – No significant differences between slick and normal-haired animals Average Daily Gain of Slick vs. Normal-haired Animals at STARS • The average daily gain over a period of a year at STARS did not differ between slick and normal-haired animals – Slick 1384 grams per day – Normal 1345 grams per day • This is comparable to results comparing slick vs. normal-haired beef animals at the same location Why didn’t the slick ones gain faster? • I don’t know for sure • Apparently the heat stress wasn’t sufficient to trigger an effect on growth under these conditions • These cattle always had access to shade and their temperatures never were recorded over 40.1 C Second Study Beef Research Unit July-August Environmental Conditions at the Beef Research Unit • Average Ambient Temperature -- 32.9 C • Average THI -- 99.7 • Highest Ambient Temperature – 36.0 C • Highest THI -- 107.0 • Highest Black Globe Temperature -- 56.5 C Hair Type Days No. Rectal Temp., C Skin Temp., C Slick 24 8 38.99 37.49 Normal 24 8 39.32 38.03 Difference - 0.33* - 0.49* Effect of Hair Type on Rectal and Skin Temperatures at the Beef Research Unit Respiration Rates of Slick vs. Normal-Haired Animals at the Beef Research Unit • Slick-haired animals 56.6 breaths per minute • Normal-haired animals 69.0 breaths per minute • This difference was significant at the 0.05 level Black Globe Temperature Categories • BGTC1 < 40.0 C • BGTC2 40.0 – 44.9 C • BGTC3 45.0 – 50.0 C • BGTC4 > 50.0 C Respirations per minute 40 45 50 55 60 65 70 75 1 2 3 4 Black globe temperature classes RPM Normal RPM Slick * * * * * (P>0.05) Reduced Respiration Rates of Slick-haired Animals • The advantage of slick-haired animals was similar to that of shaded vs. unshaded animals shown by Brown-Brandl et al. (2001) • It is also comparable to the advantage of zebu-crossbred over unadapted Bos taurus animals What is the advantage of a reduced respiration rate? • Adapted cattle are less affected by higher heat loads and thus are able to maintain lower respiration rates at the same temperatures. • They are thus more efficient, as a result of using less metabolic energy to maintain a normal body temperature. Respirations per minute 40 45 50 55 60 65 70 75 1 2 3 4 Environmental temperature classes RPM Normal RPM Slick * * * * * (P>0.05) Feed Intake of Slick vs. Normal-haired Animals • We expected that the slick-haired animals would consume more feed • Heat-stressed animals eat less • The slick ones did eat somewhat more: – Slick 27.0 g of feed per kg live wt/day – Normal 26.7 g of feed per kg live wt/day – This difference, while small, did approach significance Objective Evaluation of Quantity of Hair on Slick and Normal-haired Animals • Slick-haired animals 11.47 mg/cm2 • Normal-haired animals 17.82 mg/cm2 • This difference is significant at the 0.05 level Quantity of Black vs. White Hair on Spotted Animals • Black Areas 11.02 mg/cm2 • White Areas 18.28 mg/cm2 • This difference is almost identical and of the same probability, 0.05, as the slick vs. normal hair difference! Quantity of Black vs. White Hair on Spotted Animals • The difference in quantity of hair of slick vs. normal-haired animals was nearly twice as large in black vs. white areas • The weight of clipped white hair from slick-haired animals was only slightly less than that of clipped black hair from normal-haired animals What is the importance of these white vs black hair results? • Answer: We don’t know yet. It seems that a solid, light red animal, like that of most of the Criollo breeds might be the preferred coloration. • Holsteins with higher percentages of white have been shown to be superior in Florida but these animals don’t graze and thus, are not as susceptible to sunburn. Conclusions: • In addition to producing a shorter, shinier hair coat, the Slick Hair gene also results in animals having the ability to maintain lower rectal temperatures • This reduction in rectal temperature appears to be up to 0.5 C, the same reduction as 50% or more zebu influence in crosses provides Conclusions: • Cattle with the Slick hair gene also have slower respiration rates while maintaining lower body temperatures • This should allow them to be more efficient • Such cattle aren’t likely to be more productive unless placed under grazing conditions under heat stress What is next? • Identification of the genomic location of the Slick Hair gene • Sequencing of the Slick Hair gene • Evaluation of the impact of the Slick Hair gene on milk yield, reproduction and survival in commercial dairies in south Florida and Puerto Rico Puerto Rican Slick-Haired Holstein Cow #66 Also ……. • Production of homozygous slick, red Holsteins • Evaluation of the impact of the Slick Hair gene on growth and semen characteristics of Holstein bulls • Possible importation of Reyna semen for use in dairy crossbreeding programs First Lactation Reyna Cow in Nicaragua