Senepol Breed Research Articles

Carcass ultrasonography for the evaluation of meat quality of senepol beef

With the aim of improving meat production, livestock farmers have adopted technologies and selected quality animals, increasing the efficiency of livestock farming. In this context, ultrasound has proven to be a promising tool for selecting quality carcasses, as it is a non-invasive, fast and accurate technique that can be performed at different points on the animal's body. This technique consists of emitting high-frequency sound waves that, when penetrating the animal's tissue, generate real-time images of the internal structure of the carcass. These images make it possible to evaluate the thickness of subcutaneous fat, size and shape of the muscles, marbling and other important characteristics for the selection of animals with quality carcasses. In the specific case of the Senepol breed, the use of ultrasound to select meat animals has improved production, quality and competitiveness. This breed is known for its high-quality meat, and selecting animals using ultrasound can help maintain this characteristic, in addition to ensuring greater production efficiency. In view of the above, this study aimed to evaluate the characteristics and quality of carcasses of Senepol breed animals, in which the parameters of body structure measurements were evaluated; WEIGHT; AOL; AOL/100; RATI; SEA; EGS; EGS/100; PICANHA, using carcass ultrasound as an evaluation method and strengthening the importance of its use in livestock farming.

<p><strong>Sensitivity of Senepol and Caracu breeds to parasitism by <em>Rhipicephalus microplus</em></strong></p>

Taurine breeds and animals crossbred for genetic resistance to Rhipicephalus microplus have been the focus of several studies aimed at producing better responses of cattle to tick infestations and seeking to reduce treatment costs and improve the quality of bovine byproducts. Another way to increase gains is the introduction of taurine breeds with the goal of obtaining morphological and physiological characteristics more adapted to production. Although several studies have compared taurine and zebu breeds, little is known about the differences found within the taurine group. Therefore, the present study aimed to evaluate the sensitivity of the Senepol and Caracu breeds to artificial R. microplus infestations. For this purpose, a stall test was conducted on 16 Caracu and 14 Senepol bulls. The animals were subjected to artificial infestation with a total of 15,000 R. microplus larvae per animal. The Senepol group accounted for 71.7% of the retrieved engorged female ticks. The biological parameters analyzed that showed a significant difference included the mean number of engorged female ticks retrieved (p = 0.000), weight of engorged female ticks (p = 0.000), rate of engorged female ticks retrieved (p = 0.03) and egg mass weight (p = 0.032). Thus, the present study demonst rated a higher susceptib ility of the Senepol breed to parasitism by the Asian blue tick than the Caracu breed, providing support for new studies on the subjects of genetic resistance, animal breeding and cattle production.

7 A record of 485 viable cumulus–oocyte complexes recovered and 165 viable embryos produced in a single ovum pickup session from a Senepol breed donor

The recovery of an exceptionally high number of cumulus–oocyte complexes (COC) in a single ovum pickup (OPU) session is rare, and thus seldom reported in the literature. In the present report, we describe one of these cases. The present data refers to an OPU session performed by author A. O. Resende in a commercial beef farm, located in the rural area of the city of Barretos, Brazil, on October 15, 2019. Breed heifers (N=12) underwent OPU at a random stage of oestrous cycle without any hormonal treatment. Follicle aspirations were performed following the standard operation procedures (SOP) established by ABS Pecplan OPU team, using a portable ultrasound (DP2200, Mindray do Brasil) equipped with a 7.5-MHz microconvex probe, a vacuum pump (WTA), and 18 gauge disposable Jelco catheter (Smith Medical). Invitro embryo production (IVP) was performed at Invitro Technologies laboratory, ABS Pecplan Uberaba, located 140km from the farm. On this day, 1312 oocytes were recovered from the 12 donors. However, a single heifer produced 485 viable COC, from over 500 total COC recovered. The COC from this donor were distributed in four groups, which underwent IVF with Y-sorted semen from four Senepol sires. The invitro embryo production was performed following the SOP established by invitro Technologies, ABS Pecplan. Embryo production was compared among sires by the chi-squared test. Of the 4 sires used during IVF, sire number 4 resulted in a higher blastocyst rate compared with the others (sire 1=25.4%, sire 2=30.6%, sire 3=33.9%, and sire 4=46.3%; P<0.01).The blastocyst rate differed (P<0.01) among sires: 25.4%a (31/122), 30.6%a (37/121), 33.9%a (41/121), and 46.3%b (56/121) for bulls A, B, C, and D, respectively. From the total of 165 viable embryos produced (34.0%), 120 were transferred fresh and the remaining 45 were vitrified using the SOP established by IVB Technologies, ABS. These results highlight the huge potential variation in antral follicle population and number of COC recovered from donors within the same population, breed, and reproductive status. It also shows the potential of IVP in the generation of offspring from high genetic indices.

Estimate of in vitro embryo production based on sperm subpopulations in Senepol bulls

In cattle, in vitro embryo production (IVEP) is an important reproductive biotechnology responsible for the rapid expansion of the Senepol breed in our country. This breed has shown important results when used in crossbreeding and estimate IVEP in Senepol based on seminal analysis would be valuable for the semen cryopreservation industry, research institutes and breeders. Combining the evaluation of sperm subpopulations with analysis of other sperm attributes may help to improve fertility predictions in cattle. Therefore, the objectives of the present study were to: 1) identify and characterize motile sperm subpopulations in cryopreserved Senepol semen following the washing process carried out before in vitro fertilization, and 2) to determine an model for estimate IVEP based on sperm subpopulations in conjunction with other sperm quality analyzes. Samples of 38 cryopreserved semen from 28 Senepol bulls, chosen based on retrospective data from 386 IVEP routines, underwent the semen washing and were evaluated by the computer-assisted sperm analysis system. Sperm morphology was evaluated by wet preparation technique, and plasma and acrosomal membranes integrity, mitochondrial potential, oxidative status and chromatin resistance were analyzed by flow cytometry. After multivariate analysis of principal components and grouping, three sperm subpopulations were identified: SBP1 (fast and progressive motility), SBP2 (hyperactivated motility) and SBP3 (slow non-progressive motility). After categorization of IVEP in high, medium and low embryo yield, logistic regression analysis was applied to associate the results of subpopulations and other sperm quality variables with IVEP. The SBP1 and SBP2 variables affected embryo production, and an IVEP estimation model was generated for Senepol bulls based on these two subpopulations: embryo yield = 0.1563 + 0.0328 (SBP1) + 0.0173 (SBP2). SBP1 and SBP2 represents the absolute value of the percentage of subpopulations in semen. If the calculated value (by this equation) is close to 1, the embryo yield will be low; if is close to 2, will be medium; if is close to 3, will be high. In conclusion, three subpopulations were found for Senepol semen and, despite all analyzed variables, only SBP1 and SBP2 were included in the model to estimate IVEP in this breed.

QUALITATIVE ASPECTS OF OOCYTES FROM NELORE AND SENEPOL BREEDS REARED IN A TROPICAL REGION

The objective of this work was to evaluate the influence of the tropical climate on donor races on the quantity and quality of oocytes aspirated in Nellore and Senepol cows by means of follicular aspiration, destined to the in vitro production of embryos. The experimental design was in randomized blocks, considering each bovine female as a plot and each farm being a block totaling 14 different properties, and the number of cows used were 238 for the Nelore breed and 267 for the Senepol breed totaling 505 bovine females. The evaluation of the total number of oocytes and the quality by the quality classification of oocytes aspirated in Grade I, II, III, atresic and degenerate. According to the results we can conclude that, among the two races evaluated, a greater amount of GII oocytes is observed for the Nelore breed, and the Senepol breed in tropical climate can produce a good quantity and quality of oocytes, with the lowest amount of nude in relation to the Nelore.

PSV-26 The influence of breed, growing phase nutrition, and finishing system (pasture vs. feedlot) on the relative abundance of mRNA associated with lipid metabolism in longissimus muscle

Abstract The objective of this experiment was to evaluate the influence of beef cattle breed, nutritional treatment, and finishing strategy (pasture vs. feedlot) on the relative abundance of mRNA associated with lipid metabolism in longissimus muscle (LM). Eighty-three uncastrated males from three genetic groups: Nellore (N), ½ Angus x ½ Nellore (A) and ½ Senepol x ½ Nellore (S), were randomly assigned to dietary treatments supplied during the growing phase. Treatments consisted of mineral supplement or concentrate supplement (0.3% BW). Following the growing phase, two replicates within each treatment x breed group were randomly assigned to one of two finishing systems (Figure 1): Pasture grazing + concentrate (PC) and Conventional feedlot (CF), both are supplemented at 2% BW/had/d (Table 1). After 209 days the animals were slaughtered, an LM sample (5.0g) was removed between 12th and 13th ribs from each animal and frozen (liquid nitrogen). The relative abundance of mRNA associated with lipid metabolism was measured by qRT-PCR. Target genes include PPARα, PPARγ, SREBP1c, SCD1, LPL, FBP4, CPT2, ACOX and ACCα. The ∆∆ Ct was used to calculate the data and analyzed using the mixed procedures of SAS for a 3×2×2 factorial arrangement of treatments. Mineral supplementation during the growing phase increased (P < 0.05) the relative abundance of mRNA of PPARα and PPARγ compared to concentrate. The relative abundance of PPARγ, SREBP1c, SCD1, FABP4, ACOX, was greater (P < 0.05) in CF compared to PC. Angus LM muscle showed greater (P < 0.05) relative abundance of SREPB1c compared to Nellore and Senepol. The muscle of Nellore and Angus had greater (P < 0.05) relative abundance of PPARα SCD1 and lower (P < 0.05) of PPARγ when compared to Senepol breed. Therefore, in this study, the conventional feedlot and Angus are more positively associated with differential expression of adipogenic genes.

Segregación de polimorfismos en μ-calpaina y calpastatina en ganado para carne en Puerto Rico

Se determinó la distribución de polimorfismos de nucleótidos simples (SNP, por sus siglas en inglés) en dos regiones de calpaína (CAPN1- 316 y CAPN1-4751) y una en calpastatina (CAST) en ganado para carne criado en Puerto Rico (n=271). Las frecuencias genotípicas y alélicas se determinaron para cada SNP en las razas Senepol (n=53), Charolais (n=49), Angus (n=27), Charbray (n=38), Brahman (n=16), Cebú (n=16) y toros cruzados (n=72). Para CAPN1-316, las frecuencias genotípicas globales (n=219) fueron 0.07/CC (n=15), 0.38/CG (n=83) y 0.55/GG (n=121) con frecuencias alélicas de 0.26/C y 0.74/G. El genotipo CC estuvo ausente en las razas Charbray, Charolais, Angus, Cebú y Brahman. En toros Charolais, Cebú, Brahman y Charbray el genotipo GG fue mayor que el CG mientras lo inverso fue observado en toros Senepol. En animales Angus y en los cruces, los genotipos CG y GG se encontraron equitativamente distribuidos. Las frecuencias genotípicas globales (n=256) para CAPN1-4751 fueron 0.17/CC (n=44), 0.45/CT (n=114) y 0.38/ TT (n=98). Las frecuencias alélicas fueron 0.39/C y 0.61/T. Animales con el genotipo CT fueron más frecuentes en Charolais, Senepol, Angus y cruces. Los animales TT fueron más comunes en razas Charbray y Brahman. Para CAST, las frecuencias genotípicas globales (n=261) fueron 0.04/CC (n=10), 0.26/CT (n=68), y 0.70/TT (n=183), respectivamente, con frecuencias alélicas de 0.17/C y 0.83/T. No se encontraron animales de genotipo CC en Charolais, Angus y Brahman. El genotipo TT estuvo en mayor proporción en todas las razas y en los animales cruzados. La segregación de polimorfismos en CAPN1 y CAST puede estar implicada en diferencias en características de importancia económica en bovinos para carne criados en Puerto Rico, esta posibilidad debe ser evaluada mediante la genotipificación de un número grande de animales con registros de producción, previo a la incorporación de estos marcadores moleculares en programas de selección genética.

Comparison of tick resistance of crossbred Senepol × Limousin to purebred Limousin cattle

The comparison of resistance to natural tick infestation by Rhipicephalus microplus (Canestrini, 1887) of crossbred Senepol × Limousin and purebred Limousin cattle was investigated. The Senepol breed, originated from St Croix Island in the Caribbean is considered as a Bos taurus breed adapted to tropical conditions. Despite its B. taurus genetic background, it is believed to have a good tick resistance, but this resistance has never been assessed previously. Tick counts under natural infestation were carried out to investigate the difference of susceptibility between crossbred Senepol × Limousin and purebred Limousin cattle. Mixed-effect models were used to assess the effect of the breed on the number of ticks. Results show that Senepol × Limousin are five times less infested by ticks than purebred Limousin. These results underline the opportunity to use Senepol cattle for crossing with susceptible B. taurus breeds in tick infested areas, to combine tick resistance with beef production abilities.

Genetic Variability of Guzerat and Senepol Bovine Breeds by Microsatellite Markers

Bovine production plays economic importance in Brazil and Guzerat and Senepol breeds are producer of meat. It was aimed to analyze the genetic variability of Guzerat and Senepol breeds by microsatellite markers. The breeds were collected and genotyped for ten microsatellite loci by automatic sequencer and statistically analysed. A total of 53 alleles were observed being the average number was 5.3 in both breeds. The effective numbers of alleles were 3.36 for Guzerat and 3.11 for Senepol cattle. The Shannon indexes were 1.36 for Guzerat and 1.26 for Senepol cattle. The expected heterozigosity were 0.71 and PIC values were 0.64 in both breeds. The FIS were 0.01 and 0.11 for Guzerat and Senepol breeds, respectively and Hardy-Weinberg equilibrium were P>0.05 for Guzerat and P<0.05 for Senepol cattle. The combined discrimination powers were 0.99 in both breeds and combined exclusion powers (PE1) were 0.99 in both breeds and combined exclusion powers (PE2) were 0.96 and 0.95 for Guzerat and Senepol breeds espectively. There is genetic variability in both breed, but there are evidences of inbreeding enabling genetic drift and should be necessary to use major number of microsatellite loci to analyze with high efficiency the exclusion power (PE2).

Vaginal leiomyosarcoma in a cow from Uberlândia, Minas Gerais, Brazil

The clinical, pathological, and immunohistochemical findings associated with a vaginal leiomyosarcoma in a 12-year-old, Senepol breed of cow from Uberlândia, Minas Gerais are described. The animal had a large ulcerative neoplastic growth that originated between the base and the left-lateral vaginal wall. Histopathology revealed a tumor formed by muscle-like cells that demonstrated cellular pleomorphism, anisokaryosis, prominent and multiple nucleoli, with rare tumor giant cells. The neoplastic growth invaded adjacent adipose tissue, and contained areas of hemorrhage with discrete accumulations of inflammatory cells. By immunohistochemistry, most neoplastic cells expressed actin, while immunoreactivity to desmin was weakly expressed. These findings support a diagnosis of leiomyosarcoma, and represent the first description of a bovine vaginal leiomyosarcoma from Brazil.

The structure of a cattle stud determined using a medium density single nucleotide polymorphism array

Genetic progress depends on accurate knowledge of the genetic composition of a population or herd including level of inbreeding and parentage. However, in many circumstances, such as at an individual property level, the relationships between animals may be unknown, or at best, only partly known. In this study, we used DNA from 938 animals and genotypes from ~54 000 single nucleotide polymorphisms (SNP) to determine the genetic structure of a stud from Central Queensland. Animals on the study were bred using multi-sire mating in mobs of composite tropically adapted cattle of the Senepol, Belmont and Bonsmara breeds. Following genotyping using an array of 54 000 SNP, we were able to separate animals into breed groups using principal components and show that ~400 SNP were sufficient to separate animals into stable groups if the sample was genetically diverse. However, precise principal component values were only achieved when a few thousand SNP were used. We characterised the pedigree relationships between individuals using a genome relationship matrix. At least 3000 SNP were required to calculate accurate relationship coefficients between individuals. Around 19% of paired comparisons between animals showed similarity equivalent to sharing a great-grandparent or 1/64 shared ancestry. Approximately 8% of the individuals showed more than 10% inbreeding. To demonstrate the utility of calculating the relationship coefficients, we counted the tick burden on each animal at more than one time and then calculated the heritability of tick burden of h2 = 0.46 (±0.08). There was no significant genetic difference in tick burden between Belmont and Bonsmara cattle compared with Senepol on this property once a genetic relationship matrix was included to account for co-ancestry of individuals.

Modeling the relationship between scanned rump and 12th-rib fat in young temperate and tropical bovines: Model development and evaluation1,2

A decision support tool for predicting subcutaneous fat depths called BeefSpecs, based on the Davis growth model (DGM), has been developed by the Cooperative Research Centre for Beef Genetic Technologies. Currently, the DGM predicts 12th-rib fat thickness (RFT, mm). To allow predictions of fat thickness at the P8 rump (P8FT, mm) site, the standard carcass fat measurement in the Australian beef industry, a relationship was developed between ultrasound RFT and P8FT in steers and heifers from temperate (Angus, Hereford, Shorthorn, and Murray Grey) and tropical (Brahman, Belmont Red, and Santa Gertrudis) breed types. Model development involved fitting various combinations of sex, breed type (BrT), BW, age, and RFT to produce 6 models. The models were challenged with data from 3 independent data sets: 1) Angus steers from 2.4 generations of divergent selection for and against residual feed intake; 2) 2 tropically adapted genotypes [Brahman and tropically adapted composites (combinations of Belmont Red, Charbray, Santa Gertrudis, Senepol, and Brahman breeds)]; and 3) a study using sires from Charolais, Limousin, Belgian Blue, and Black and Red Wagyu breeds and 3 genetic lines of Angus to create divergence in progeny in terms of genetic potential for intramuscular fat percent and retail beef yield. When challenged with data from Angus cattle, the mean biases (MB, mm) for models A to F were -1.23, -0.56, -0.56, -0.02, 0.14, and 0.04, and the root mean square errors of predictions (mm) were 1.53, 0.97, 0.97, 0.92, 0.93, and 0.91, respectively. When challenged with data from Brahman cattle, MB were 0.04, -0.22, -0.14, 0.05, -0.11, and 0.02 and root mean square errors of predictions were 1.30, 1.29, 1.27, 1.23, 1.37, and 1.29, respectively. Generally, model accuracy indicated by MB tended to be less for model E, which contained age rather than BW as a covariate. Models B and C were generally robust when challenged with data from Angus, Brahman, and Tropical Composite cattle as well as crossbred cattle with temperate sires. Model D, which did not contain age, performed the most consistently and was selected for inclusion in the DGM: P8FT, mm = -3.6 (+/-0.14) + 1.3 (+/-0.13) x sex + 0.11 (+/-0.13) x BrT + 0.014 (+/-4.8E(-4)) x BW + 0.96 (+/-0.01) x RFT - 0.73 (+/-0.08) x sex x BrT - 3.8E(-3) (+/-4.2E(-4)) x sex x BW - 0.09 (+/-0.01) x sex x RFT + 1.3E(-3) (+/-3.7E(-4)) x BrT x BW + 0.24 (+/-0.01) x BrT x RFT (adjusted R(2) = 0.86; SE = 0.013). Model D has been implemented in BeefSpecs to predict P8FT.

Genetic divergence in cellular resistance to heat shock in cattle: differences between breeds developed in temperate versus hot climates in responses of preimplantation embryos, reproductive tract tissues and lymphocytes to increased culture temperatures

The detrimental effects of heat stress on fertility in cattle are less pronounced in heat-tolerant breeds. Although these genetic differences reflect differences in thermoregulation, cells from heat-tolerant breeds are less adversely compromised by increased temperature (that is, heat shock) than cells from heat-sensitive breeds. Experiments were performed to test the hypothesis that cells and tissues from two thermotolerant breeds (Brahman and Senepol) are better able to survive and function after exposure to increased temperature than cells and tissues from two thermosensitive breeds (Holstein and Angus). Exposure of embryos at>eight-cell stage at day 5 after insemination to heat shock of 41.0 degrees C for 6 h decreased development to the blastocyst stage and the number of cells per embryo. However, the deleterious effect of heat shock on blastocyst formation and the number of cells per embryo was less pronounced for Brahman than for Holstein and Angus breeds. Embryos from Senepol cows had very low development and it was not possible to determine heat shock effects in this breed. In contrast to the sensitivity of embryos to heat shock, there was no effect of a 41.0 degrees C heat shock on [(3)H]leucine incorporation into proteins secreted by oviductal or endometrial explants. Lymphocytes from Brahman and Senepol cows were more resistant to heat-induced apoptosis than lymphocytes from other breeds. Heat shock reduced lymphocyte glutathione content but the magnitude of the decrease was not affected by breed. In conclusion, embryos from Brahman cows are more resistant to heat shock than embryos from Holstein or Angus cows. Genetic differences are also present in thermotolerance for apoptosis response in lymphocytes, with Brahman and Senepol cattle being more resistant to heat shock than Angus and Holstein breeds. It is likely that the evolutionary forces that led to the Brahman and Senepol breeds being adapted to hot climates resulted in the selection of genes controlling resistance to cellular heat shock.

Age-related changes in scrotal circumference, testis size and sperm reserves in bulls of the tropically adapted Senepol breed

Testicular characteristics were measured in a random population of Senepol bulls representing three farms on St. Croix (17°N, 64°W), during a 5 year period. Bulls were maintained on native, tropical grass/legume pasture throughout all stages of development. Scrotal circumference (SC; 317 measurements, 267 bulls) increased in a curvilinear relationship ( P < 0.001) with both age ( r 2 = 0.816) and body weight ( r 2 = 0.856) and reached a mean maximum SC of 42.4 cm at 6–7 years of age. There was a linear relationship ( n=84; P<0.001) between SC and total testicular weight ( r 2=0.883), testis length ( r 2=0.800) and testis width ( r 2=0.969). Testicular weights and dimensions were highly correlated ( P<0.001) with epididymal weights. Mean daily sperm production rate (14.1 × 10 9 spermatozoa g −1) did not differ between pubertal ( n=5), postpubertal ( n=5) and mature bulls ( n = 5); however, total daily sperm production and epididymal reserves increased ( P< 0.05) from 4.9 × 10 9 and 6.9 × 10 9 to 10.1 × 10 9 and 42.1 × 10 9 spermatozoa in pubertal and mature bulls, respectively. The data indicate that SC, testicular weight and sperm reserves of Senepol bulls more closely resemble those reported for Bos taurus than Bos indicus genotypes.

Preweaning Breed-of-Sire Comparisons Involving The Senepol Breed of Cattle

Preweaning data collected at two locations (Kentucky, Louisiana) were utilized to evaluate breed-of-sire comparisons involving the Senepol breed of cattle. For the Kentucky study, calves sired by Senepol bulls were 1.3 kg heavier (P less than .05) at birth than calves sired by Hereford bulls; however, weaning weights were similar for the two sire groups. For the Louisiana study, calves sired by Longhorn bulls were 5.3 kg lighter (P less than .01) at birth, 20 kg lighter (P less than .01) at weaning and had weaning condition scores .5 unit less (P less than .01) than the average of calves sired by Red Poll and Senepol bulls. Also, heifers exposed to Longhorn bulls weaned 23 kg less (P less than .01) calf per heifer exposed than the average of heifers exposed to Red Poll and Senepol bulls. Calves sired by Red Poll bulls were 1.2 kg heavier (P less than .01) at birth and 12 kg heavier (P less than .01) at weaning than those sired by Senepol bulls; however, the Senepol-sired calves received higher (P less than .01) condition scores at weaning. Heifers exposed to Red Poll bulls weaned 20 kg more (P less than .05) calf per heifer exposed than did heifers exposed to Senepol bulls.