RESUMEN
Considering the economic and commercial efficiency of the beef production chain, the yield and quality of the meat produced must also be included in breeding programs. For the Nellore breed, including the polled herd, these aspects have not been much studied. The aim of this study was to estimate genetic parameters for scrotal circumference adjusted to 365 (SC365) and 450 (SC450) days of age, age at first calving (AFC), accumulated productivity (AP), stayability (STAY), longissimus muscle area (LMA), thickness of subcutaneous fat over the 12th-13th ribs (BF), thickness of subcutaneous fat over the rump (RF), and shear force measured by Warner-Bratzler shear force (WBSF) of polled Nellore cattle. Bayesian analyses were performed by adopting a linear animal model, whereas STAY analyses used the linear threshold model. Heritability estimates were 0.31 (SC365), 0.37 (SC450), 0.16 (AFC), 0.25 (AP), 0.16 (STAY), 0.30 (LMA), 0.13 (BF), 0.24 (RF), and 0.15 (WBSF), indicating moderate response to selection. Genetic and residual correlations between SC365 and SC450 were high (0.91 and 0.74, respectively), as well as the genetic correlations of AP with SC365, SC450, AFC, and STAY (0.61, 0.62, - 0.69, and 0.83, respectively). Genetic and residual correlations of WBSF with reproductive and carcass characteristics exhibited high standard deviations, however favorable. Based on the results, it is expected that in the medium term, animals with greater sexual precocity will also have greater accumulated productivity and longer permanence of females in the herd, along with superior carcass traits. However, due to the low heritabilities and small genetic associations with reproductive traits, fat thickness characteristics (BF and RF) will still require direct selection.
Asunto(s)
Carne , Reproducción , Animales , Bovinos/genética , Femenino , Teorema de Bayes , Fenotipo , Reproducción/genéticaRESUMEN
Cloning procedures often interfere with conceptus growth and life ex utero, in a set of symptoms known as abnormal offspring syndrome (AOS). The aim of the present study was to compare the developmental pattern of in vivo-derived (IVD), IVF-derived and handmade cloning-derived (NT-HMC) Day 225 bovine concepti using established procedures. Pregnancy diagnosis was performed on Day 30 following blastocyst transfer on Day 7. Conceptus morphometry was assessed by ultrasonography on Day 51, and on Day 225 pregnant cows were killed for morphological examination of concepti. Pregnancy outcome was similar between groups, with greater pregnancy losses in the first trimester (70.6%) and smaller fetuses on Day 51 in the NT-HMC group than in the IVD (14.3%) and IVF (20.0%) groups. However, NT-HMC-derived concepti were twofold larger on Day 225 of gestation than controls. A higher frequency (63.5%) of placentomes larger than the largest in the IVD group was observed in the NT-HMC group, which may be relevant to placental function. Conceptus traits in the IVF group were similar to the IVD controls, with only slight changes in placentome types. Morphological changes in cloned concepti likely affected placental function and metabolism, disrupting the placental constraining mechanism on fetal growth in mid- to late pregnancy.
Asunto(s)
Clonación de Organismos , Desarrollo Embrionario/fisiología , Animales , Bovinos , Transferencia de Embrión/veterinaria , Femenino , Fertilización In Vitro/veterinaria , Técnicas de Transferencia Nuclear/veterinaria , Embarazo , Resultado del Embarazo , Ultrasonografía Prenatal/veterinariaRESUMEN
Zebu () cattle, mostly of the Nellore breed, comprise more than 80% of the beef cattle in Brazil, given their tolerance of the tropical climate and high resistance to ectoparasites. Despite their advantages for production in tropical environments, zebu cattle tend to produce tougher meat than Bos taurus breeds. Traditional genetic selection to improve meat tenderness is constrained by the difficulty and cost of phenotypic evaluation for meat quality. Therefore, genomic selection may be the best strategy to improve meat quality traits. This study was performed to compare the accuracies of different Bayesian regression models in predicting molecular breeding values for meat tenderness in Polled Nellore cattle. The data set was composed of Warner-Bratzler shear force (WBSF) of longissimus muscle from 205, 141, and 81 animals slaughtered in 2005, 2010, and 2012, respectively, which were selected and mated so as to create extreme segregation for WBSF. The animals were genotyped with either the Illumina BovineHD (HD; 777,000 from 90 samples) chip or the GeneSeek Genomic Profiler (GGP Indicus HD; 77,000 from 337 samples). The quality controls of SNP were Hard-Weinberg Proportion -value ≥ 0.1%, minor allele frequency > 1%, and call rate > 90%. The FImpute program was used for imputation from the GGP Indicus HD chip to the HD chip. The effect of each SNP was estimated using ridge regression, least absolute shrinkage and selection operator (LASSO), Bayes A, Bayes B, and Bayes Cπ methods. Different numbers of SNP were used, with 1, 2, 3, 4, 5, 7, 10, 20, 40, 60, 80, or 100% of the markers preselected based on their significance test (-value from genomewide association studies [GWAS]) or randomly sampled. The prediction accuracy was assessed by the correlation between genomic breeding value and the observed WBSF phenotype, using a leave-one-out cross-validation methodology. The prediction accuracies using all markers were all very similar for all models, ranging from 0.22 (Bayes Cπ) to 0.25 (Bayes B). When preselecting SNP based on GWAS results, the highest correlation (0.27) between WBSF and the genomic breeding value was achieved using the Bayesian LASSO model with 15,030 (3%) markers. Although this study used relatively few animals, the design of the segregating population ensured wide genetic variability for meat tenderness, which was important to achieve acceptable accuracy of genomic prediction. Although all models showed similar levels of prediction accuracy, some small advantages were observed with the Bayes B approach when higher numbers of markers were preselected based on their -values resulting from a GWAS analysis.
Asunto(s)
Cruzamiento , Genoma , Genómica/métodos , Carne/normas , Animales , Teorema de Bayes , Brasil , Bovinos/genética , Frecuencia de los Genes , Estudio de Asociación del Genoma Completo , Genotipo , Carne/análisis , Análisis de Secuencia por Matrices de Oligonucleótidos/veterinaria , Polimorfismo de Nucleótido SimpleRESUMEN
The objective of this study was to evaluate the performance and health of Holstein calves fed low or high milk supply (MSP) with or without symbiotic complex (SYM) supplementation, consisting of prebiotics, probiotics, and fibrolytic enzymes. Thirty-two Holstein calves with body weight (BW) of 34 ± 7 kg were distributed in a randomized block design in a 2 × 2 factorial arrangement. Treatments consisted of low and high MSP: 10 % of BW from 1st to 8th weeks after birth (low) and 20 % BW from 1st and 2nd weeks after birth, 15 % BW for the 3rd and 4th weeks after birth, and 10 % BW from 5th and 8th weeks after birth (high). Solid ration was supplied in addition to milk. Intake, ADG, diet digestibility, and fecal consistency index were evaluated. Low and high MSP groups tended (P < 0.10) to differ in calf growth, final BW (69 vs. 73 kg), post-weaning average weight gain (548 vs. 788 g/day), and final average weight gain (549 vs. 646 g/day) in low and high MSP calves, respectively. There was an interaction between MSP level and SYM on the digestibilities of dry matter (DM) and neutral detergent fiber (NDF) (P < 0.10). In the low MSP group, inclusion of SYM increased digestibility of DM (0.720 to 0.736 g/kg) and NDF (0.758 to 0.783 g/kg). The inclusion of SYM improved calf health (P < 0.10) with a fecal score of 0.31 compared to 0.42 without SYM. Milk-feeding level was an important factor in calf performance, while SYM supplementation improved diet digestibility and animal health.
Asunto(s)
Bovinos/crecimiento & desarrollo , Dieta/veterinaria , Conducta Alimentaria , Leche , Probióticos/administración & dosificación , Animales , Animales Recién Nacidos/crecimiento & desarrollo , Peso Corporal , Brasil , Suplementos Dietéticos , Clima Tropical , Destete , Aumento de PesoRESUMEN
The objective of this study was to evaluate the genetic variability of body composition traits measured by ultrasound, growth traits, and visual scores as well as their genetic associations in Nelore cattle. A total of 9,765, 13,285, 13,061, 12,811, 3,484, 3,484, 3,483, and 3,303 records of weight at time of ultrasound measure (W550), 12th-13th rib LM area (LMA), backfat thickness (BF), rump fat thickness (RF), visual scores for body structure (BS), finishing precocity (FP), muscling (MS), and sheath and navel characteristics (SN), respectively, were used. The model included contemporary group (defined as year and season of birth, sex, and management group) as a fixed effect and age of dam at calving and age of the animal (linear and quadratic effects) as covariates. The direct additive genetic effect was included as a random effect. The analyses also included 46,157 observations of BW adjusted to 120 d. The (co)variance components were estimated by the restricted maximum likelihood method using a multitrait animal model. Heritability estimates for W550, LMA, BF, RF, BS, FP, MS, and SN were 0.37 ± 0.030, 0.33 ± 0.03, 0.24 ± 0.02, 0.28 ± 0.03, 0.24 ± 0.04, 0.38 ± 0.05, 0.29 ± 0.05, and 0.38 ± 0.06, respectively. The estimated genetic correlations between visual scores and LMA were moderate and positive, ranging from 0.37 to 0.44. Similar results were obtained for the estimated genetic correlations between FP and MS with fat thickness measures (BF and RF). Low genetic correlations were estimated between SN and BS and between SN and the body composition traits, indicating that selection for body composition traits and BS will not affect sheath and navel size. The estimated genetic correlations between weight adjusted to 120 d of age (W120) and W550 and BS were high (0.87 and 0.91) and moderate with LMA (0.49 and 0.55), FP (0.37 and 0.41), and MS (0.47 and 0.55). The visual scores and ultrasound-measured body composition traits have enough genetic variation for selection purposes in Nelore cattle. Selection based on visual scores for body structure, finishing precocity and muscling should lead to desired changes in body composition albeit much more slowly than direct selection on those traits measured by ultrasound. Selection for heavier BW at early ages should lead to favorable changes in yearling LM area and visual scores.
Asunto(s)
Composición Corporal/genética , Composición Corporal/fisiología , Bovinos/genética , Bovinos/fisiología , Tejido Adiposo/diagnóstico por imagen , Tejido Adiposo/fisiología , Envejecimiento , Animales , Brasil , Femenino , Masculino , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/fisiología , UltrasonografíaRESUMEN
Se realizó una nefrectomía laparoscópica en un cadáver adulto con el propósito de identificar los elementos anatómicos propios de este campo quirúrgico bajo visión de la óptica laparoscópica. La preparación anatómica fue tratada para simular lo mejor posible las condiciones quirúrgicas. Para ello se realizó una inyección del sistema venoso con látex al 60 por ciento coloreado artificialmente con el propósito de aumentar el contraste del sistema venoso principal. El modelo anatómico permitió reproducir todos y cada uno de los pasos de la técnica quirúrgica sin dificultades, y la utilización del instrumental laparoscópico no planteó dificultades adicionales, a pesar de que el material anatómico estaba formolozado. Se concluye que el modelo anatómico es esencial, en este tipo de cirugía, para instruir al cirujano interviniente en cuanto a identificación y manejo de los elementos constitutivos del hilio renal bajo visión óptica quirúrgica(AU)
Asunto(s)
Humanos , Adulto , Nefrectomía , Laparoscopía , Laparoscopía , Riñón/anatomía & histología , Riñón/cirugía , CadáverRESUMEN
Se realizó una nefrectomía laparoscópica en un cadáver adulto con el propósito de identificar los elementos anatómicos propios de este campo quirúrgico bajo visión de la óptica laparoscópica. La preparación anatómica fue tratada para simular lo mejor posible las condiciones quirúrgicas. Para ello se realizó una inyección del sistema venoso con látex al 60 por ciento coloreado artificialmente con el propósito de aumentar el contraste del sistema venoso principal. El modelo anatómico permitió reproducir todos y cada uno de los pasos de la técnica quirúrgica sin dificultades, y la utilización del instrumental laparoscópico no planteó dificultades adicionales, a pesar de que el material anatómico estaba formolozado. Se concluye que el modelo anatómico es esencial, en este tipo de cirugía, para instruir al cirujano interviniente en cuanto a identificación y manejo de los elementos constitutivos del hilio renal bajo visión óptica quirúrgica