Browsing by Author "Mateescu, Raluca G."
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Item Determination of the optimum contribution of Brahman genetics in an Angus-Brahman multibreed herd for regulation of body temperature during hot weather(Oxford University Press, 2018-05-10) Mateescu, Raluca G.; Elzo, Mauricio A.; Hansen, Peter J.; Dikmen, Serdal; Uludağ Üniversitesi/Veterinerlik Fakültesi/Zootekni Anabilim Dalı.; 0000-0002-5611-4993; A-5731-2018; 8280302600The objective was to evaluate the influence of varying amounts of Brahman genetics on body temperature under pasture conditions during hot weather. Vaginal temperatures were measured at 5-min intervals for 3 to 5 d on four occasions during August and September from a total of 190 pregnant cows that were either Angus, 2/8 Brahman (remainder Angus), Brangus (3/8 Brahman), 4/8 Brahman, 6/8 Brahman or Brahman. Vaginal temperature was higher for the first two replicates than for the second two replicates. In the first two replicates, average vaginal temperature did not differ between genetic groups, but average vaginal temperature from 1500 to 1900 h was lower for Brahman than other groups. In the second two replicates, average vaginal temperature was lower for cows that were 4/8 or higher Brahman than for cows that were 2/8 Brahman or Angus. Average vaginal temperature from 1500 to 1900 h was lower for cows that were 4/8 or higher Brahman than for cows that were 2/8 Brahman or Angus. In addition, Brahman cows had lower vaginal temperatures than cows that were 4/8 Brahman or 3/8 Brahman (i.e., Brangus). In one replicate, a tracking device was used to map cow location. At 1200 to 1300 h, cows that were 6/8 Brahman or Brahman had fewer observations near the tree line (i.e., in shade) than cows that were 4/8 Brahman or less. At 1500 to 1600 h, cows that were 4/8 or higher Brahman experienced fewer observations near the tree line than cows that contained a lower fraction of Brahman genetics. In summary, a minimum of 4/8 Brahman genetics was required to increase the ability to regulate body temperature and at least 6/8 Brahman when heat stress was severe. It is likely, therefore, that using Brahman genetics to optimize adaptation to thermal stress under conditions of severe heat stress requires a preponderance of Brahman genes.Item Genetic parameters for hair characteristics and core body temperature in a multibreed Brahman-Angus herd(Oxford University Press, 2019-06-19) Davila, Kaitlyn M. Sarlo; Hamblen, Heather; Hansen, Peter J.; Oltenacu, Pascal A.; Mateescu, Raluca G.; Dikmen, Serdal; Bursa Uludağ Üniversitesi/Veteriner Fakültesi/Zootekni ve Hayvan Besleme Bölümü.; 0000-0002-5611-4993; A-5731-2018; 8280302600Thermal stress in hot humid conditions limits cattle production. The objectives for this study were to estimate genetic parameters for hair characteristics and core body temperature under low and high temperature humidity index (THI) conditions. Hair samples were collected and measured for length and diameter. Core body temperature was measured as vaginal temperature every 15 min over a 5-d period using an iButton temperature measuring device implanted in a blank CIDR in 336 heifers from the University of Florida multibreed herd (ranging from 100% Angus to 100% Brahman). Restricted maximum likelihood procedures were used to estimate heritabilities from multiple bivariate animal models using the WOMBAT program. Estimates of heritability for hair diameter, undercoat length, topcoat length, body temperature under low THI conditions, and body temperature under high THI conditions were 0.50, 0.67, 0.42, 0.32, and 0.26, respectively. The genetic parameters estimated in this study indicate a large, exploitable genetic variance which can be selected upon to improve tolerance in cattle. Breed effects for differing compositions of Brahman and Angus were also estimated. As Brahman breed composition increased by 25% undercoat length, topcoat length, body temperature under low THI conditions, and body temperature under high THI conditions decreased by 1.32 mm, 2.94 mm, 0.11 degrees C, and 0.14 degrees C, respectively. Under both low and high THI conditions, cattle with 25% Brahman breed composition or greater maintained a significantly lower body temperature than the 100% Angus breed group. The incorporation of Brahman germplasm is recommended for herds that often experience heat stress conditions in order to increase resilience to heat stress.Item Genome-wide association study identifies variants associated with hair length in Brangus cattle(Wiley, 2020-10) Sarlo, K. M. Davila; Howell, Alyssa; Nunez, Adrian; Orelien, Arseia; Roe, Victoria; Rodriguez, Edgardo; Mateescu, Raluca G.; Dikmen, Serdal; Uludağ Üniversitesi/Veteriner Fakültesi/Zootekni Anabilim Dalı.; 0000-0002-5611-4993; A-5731-2018; 8280302600Thermal stress limits beef cattle production and a shorter hair coat is a key thermoregulative adaptation that allows cattle to lose heat more efficiently. The objective of this study was to identify genetic variants associated with the length of the undercoat and topcoat of cattle utilizing 1456 Brangus heifers genotyped with the Bovine GGP F250 array. Seven SNPs in the PCCA gene were significantly associated with undercoat length. PCCA belongs to the biotin transport and metabolism pathway. Biotin deficiency has been reported to cause hair loss. Four SNPs in an 110 kb including a missense mutation in the PRLR gene were significantly associated with topcoat length. Whereas the association of this polymorphism with hair length is novel, the SLICK mutation in PRLR has previously been demonstrated to significantly impact hair length in cattle. These newly detected genetic variants may contribute to a shorter hair coat and more thermotolerant animals.Publication President oral presentation pick: Phenotypic plasticity of heat tolerance in beef cattle(Oxford Univ Press, 2020-11-01) Mateescu, Raluca G.; Davila, Kaitlyn M. Sarlo; Dikmen, Serdal; Nunez, Andrea; Rodriguez, Eduardo; Oltenacu, Pascal; DİKMEN, SERDAL; Bursa Uludağ Üniversitesi/Veteriner Fakültesi.; 0000-0002-5611-4993; A-5731-2018