549 resultados para nellore
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The use of relatively low numbers of sires in cattle breeding programs, particularly on those for carcass and weight traits in Nellore beef cattle (Bos indicus) in Brazil, has always raised concerns about inbreeding, which affects conservation of genetic resources and sustainability of this breed. Here, we investigated the distribution of autozygosity levels based on runs of homozygosity (ROH) in a sample of 1,278 Nellore cows, genotyped for over 777,000 SNPs. We found ROH segments larger than 10 Mb in over 70% of the samples, representing signatures most likely related to the recent massive use of few sires. However, the average genome coverage by ROH (>1 Mb) was lower than previously reported for other cattle breeds (4.58%). In spite of 99.98% of the SNPs being included within a ROH in at least one individual, only 19.37% of the markers were encompassed by common ROH, suggesting that the ongoing selection for weight, carcass and reproductive traits in this population is too recent to have produced selection signatures in the form of ROH. Three short-range highly prevalent ROH autosomal hotspots (occurring in over 50% of the samples) were observed, indicating candidate regions most likely under selection since before the foundation of Brazilian Nellore cattle. The putative signatures of selection on chromosomes 4, 7, and 12 may be involved in resistance to infectious diseases and fertility, and should be subject of future investigation.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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An important goal of Zebu breeding programs is to improve reproductive performance. A major problem faced with the genetic improvement of reproductive traits is that recording the time for an animal to reach sexual maturity is costly. Another issue is that accurate estimates of breeding values are obtained only a long time after the young bulls have gone through selection. An alternative to overcome these problems is to use traits that are indicators of the reproductive efficiency of the herd and are easier to measure, such as age at first calving. Another problem is that heifers that have conceived once may fail to conceive in the next breeding season, which increases production costs. Thus, increasing heifer's rebreeding rates should improve the economic efficiency of the herd. Response to selection for these traits tends to be slow, since they have a low heritability and phenotypic information is provided only later in the life of the animal. Genome-wide association studies (GWAS) are useful to investigate the genetic mechanisms that underlie these traits by identifying the genes and metabolic pathways involved. Data from 1853 females belonging to the Agricultural Jacarezinho LTDA were used. Genotyping was performed using the BovineHD BeadChip (777 962 single nucleotide polymorphisms (SNPs)) according to the protocol of Illumina - Infinium Assay II ® Multi-Sample HiScan with the unit SQ ™ System. After quality control, 305 348 SNPs were used for GWAS. Forty-two and 19 SNPs had a Bayes factor greater than 150 for heifer rebreeding and age at first calving, respectively. All significant SNPs for age at first calving were significant for heifer rebreeding. These 42 SNPs were next or within 35 genes that were distributed over 18 chromosomes and comprised 27 protein-encoding genes, six pseudogenes and two miscellaneous noncoding RNAs. The use of Bayes factor to determine the significance of SNPs allowed us to identify two sets of 42 and 19 significant SNPs for heifer rebreeding and age at first calving, respectively, which explain 11.35 % and 6.42 % of their phenotypic variance, respectively. These SNPs provide relevant information to help elucidate which genes affect these traits.
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The aim of this study was to identify candidate genes and genomic regions associated with ultrasound-derived measurements of the rib-eye area (REA), backfat thickness (BFT) and rumpfat thickness (RFT) in Nellore cattle. Data from 640 Nellore steers and young bulls with genotypes for 290 863 single nucleotide polymorphisms (SNPs) were used for genomewide association mapping. Significant SNP associations were explored to find possible candidate genes related to physiological processes. Several of the significant markers detected were mapped onto functional candidate genes including ARFGAP3, CLSTN2 and DPYD for REA; OSBPL3 and SUDS3 for BFT; and RARRES1 and VEPH1 for RFT. The physiological pathway related to lipid metabolism (CLSTN2, OSBPL3, RARRES1 and VEPH1) was identified. The significant markers within previously reported QTLs reinforce the importance of the genomic regions, and the other loci offer candidate genes that have not been related to carcass traits in previous investigations.
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The objective of this study was to analyze the influence of genetic group (GG) of the calf during gestation, mobilization of body reserves and period of postpartum anestrus in Nellore cows. Thirty-seven primiparous and multiparous cows were used: 24 gave birth to Nellore (NEL), and 13 gave birth to 1/2 Simmental x 1/2 Nellore (SIM) calves. According to the date of calving, cows were divided into three blocks, with intervals of 20 days between blocks. The body condition (BC) of the cows was estimated subjectively on a scale from 0 to 5 points, with intermediate grading of 0.5 points. We measured the thickness of subcutaneous fat (SF) between the 12th and 13th ribs and rump by ultrasound. Blood samples from each cow were collected weekly from the third week after birth until weaning, to analyze the level of progesterone; in the samples collected until 16 weeks postpartum, we analyzed the concentration of nonesterified fatty acids(NEFA). The gestation period of mothers of NEL calves was eight days longer, on average. The variables relating to the mobilization of body reserves (NEFA, BC and SF) were not influenced by calf GG, with the only significant effects being the number of days postpartum, witha peak in the concentration of NEFA between the sixth and eighth weeks and linear decrease in BC and NF. Mothers of NEL calves remained in anestrus for 4.6 weeks longer than the mothers of crossbred calves.
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The objective of this study was to investigate the influence of lineage of oocytes donors on the number and quality of oocytes obtained through ultrasound-guided follicular aspiration in Nellore breed cows derived from two lineages of bulls (Karvadi; K and Taj-Mahal; T). Both maternal (Km and Tm) and paternal (Kp and Tp) lineages, as well as their combinations were investigated. Oocyte aspirations were repeatedly performed with an aspiration interval of 15 days in 56 donor females. Recovered cumulus oocyte-complexes (COCs) were counted, morphologically examined and classified into seven categories (grades from I to VII) according to the number of layers of the cumulus oocyte and cytoplasm appearance. The mean number of oocytes retrieved from donors of lineage Tp-Tm was significantly higher (28.23±1.92, P<0.05) than those obtained from lineages Kp-Tm, Kp-Km, and Tp-Km (21.34±1.32, 21.28±1.73, and 16.72±1.31, respectively). There was no significant difference in the mean number of recovered oocytes between donors of lineages Kp-Km and Kp-Tm, whereas animals of lineage Tp-Km yielded the lowest number of oocytes. Higher mean number of grade III oocytes was recovered from donors of lineage Kp than lineage Tp (10.11±0.66 versus 8.79±0.58, respectively), with more grade III oocytes being obtained in both lineages as compared to the others. Paternal lineage did not influence the quality of recovered oocytes in any other category, but both Kp and Tp yielded a great mean number of oocytes graded as I, II, and III (3.14±0.21; 4.93±0.33, and 10.11±0.66 versus 3.19±0.21, 5.59±0.44, and 8.79±0.58, respectively) than those classified as IV, V, VI, and VII. However, when considering the data from the maternal lineage significantly more oocytes (P<0.05) of grade I, II and III were obtained from Taj-Mahal (11.67 ± 0.67, 5.9±0.42 and 3.64±0.25, respectively) than for lineage Karvadi, with similar results for oocytes of grades IV, V, VI, and VII. Similarly to the paternal lineage, the number of oocytes of grade III was superior (P<0.05) when compared to other categories for both lineages. In conclusion, we demonstrate here a direct influence of lineage of oocyte donor on the production and quality of oocytes obtained through ultrasound-guided follicular aspiration in Nellore cows.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The objective of this study was to determine the effect of the dietary inclusion of lipid-based diets (whole cottonseed and protected fat) on the centesimal composition, fatty acid profile, and sensory properties of meat from finishing Nellore cattle. The study was carried out from August to October 2009. Thirty nine uncastrated Nellore males with average initial body weight of 494.1 ± 10.1 kg and 36 months of age were housed for 63 days in pens with thirteen animals each. A completely randomized design with three treatments and thirteen replications was used. The treatments evaluated were: feed with 2.50% cottonseed (control diet); feed with 11.50% cottonseed; and feed with 3.13% cottonseed added of protected lipid (PL), all on a dry matter basis. No differences between treatments were observed for moisture, protein, and ash contents. However, the addition of protected fat caused an increase in the percentage of ether extract in the meat. Diets containing cottonseed or protected lipid did not affect fatty acid concentration in the meat. The intensity of the aroma, strange aroma, flavor, strange flavor, juiciness, color, and overall appearance were similar between treatments, except for tenderness, which was positively affected in cattle fed a diet in which the only lipid source was cottonseed. The study demonstrated that the addition of PL in the diets of finishing cattle led to greater levels of intramuscular fat, but to less tender meat than the other treatments.
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A lógica fuzzy admite infinitos valores lógicos intermediários entre o falso e o verdadeiro. Com esse princípio, foi elaborado neste trabalho um sistema baseado em regras fuzzy, que indicam o índice de massa corporal de animais ruminantes com objetivo de obter o melhor momento para o abate. O sistema fuzzy desenvolvido teve como entradas as variáveis massa e altura, e a saída um novo índice de massa corporal, denominado Índice de Massa Corporal Fuzzy (IMC Fuzzy), que poderá servir como um sistema de detecção do momento de abate de bovinos, comparando-os entre si através das variáveis linguísticas )Muito BaixaM, ,BaixaB, ,MédiaM, ,AltaA e Muito AltaM. Para a demonstração e aplicação da utilização deste sistema fuzzy, foi feita uma análise de 147 vacas da raça Nelore, determinando os valores do IMC Fuzzy para cada animal e indicando a situação de massa corpórea de todo o rebanho. A validação realizada do sistema foi baseado em uma análise estatística, utilizando o coeficiente de correlação de Pearson 0,923, representando alta correlação positiva e indicando que o método proposto está adequado. Desta forma, o presente método possibilita a avaliação do rebanho, comparando cada animal do rebanho com seus pares do grupo, fornecendo desta forma um método quantitativo de tomada de decisão para o pecuarista. Também é possível concluir que o presente trabalho estabeleceu um método computacional baseado na lógica fuzzy capaz de imitar parte do raciocínio humano e interpretar o índice de massa corporal de qualquer tipo de espécie bovina e em qualquer região do País.
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Avaliaram-se os coeficientes de digestibilidade do extrato etéreo (EE), proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), hemicelulose (HCEL) e celulose (CEL) de uma ração completa, composta por 44,3% de feno de braquiária, 55% de concentrado e 0,7% de mistura mineral, fornecida a bovinos de diferentes grupos genéticos (Gir, Nelore, Guzerá, Santa Gertrudis e Caracu), pelas metodologias de coleta total de fezes e com indicador interno (lignina em detergente ácido - LDA), em delineamento inteiramente casualizado, com três repetições por grupo genético, com análise de variância individual dentro de cada metodologia e uma análise de correlação entre as metodologias. Não houve diferença entre grupos genéticos para a digestibilidade de EE, PB, FDN, FDA, HCEL e CEL, pelas metodologias de coleta total de fezes e com LDA, com médias de 44,28 e 40,38%; 52,46 e 49,51%; 57,04 e 54,25%; 37,71 e 34,04%; 71,66 e 69,68%; e 48,27 e 45,20%, respectivamente. As digestibilidades da PB, FDA e CEL não mostraram correlação. A LDA foi eficiente na estimativa da digestibilidades e os nutrientes foram utilizados de forma semelhante pelos diferentes grupos genéticos.
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Avaliou-se a digestibilidade da matéria seca (DMS), matéria orgânica (DMO) e energia bruta (DEB) e os nutrientes digestíveis totais (NDT) de uma ração completa, composta por 44,3% de feno de capim-braquiaria, 55% de concentrado e 0,7% de mistura mineral, fornecida a bovinos de diferentes grupos genéticos (Gir, Nelore, Guzerá, Santa Gertrudis e Caracu), pelas metodologias de coleta total de fezes e com indicador interno (lignina em detergente ácido -- LDA), em delineamento inteiramente casualizado, com três repetições por grupo genético, com análise de variância individual dentro de cada metodologia e uma análise de correlação entre as metodologias. As correlações foram médias ( 0,47 a 0,51) e significativas (P<0,0602; P<0,0697; P<0,0747; P<0,0522), respectivamente, para DMS, DMO, DEB e para NDT. A recuperação do indicador (95,06%) foi semelhante entre os grupos genéticos. Não houve diferença entre grupos genéticos para DMS, DMO, DEB e nos valores de NDT pelas metodologias de coleita total de fezes e com LDA, com médias de 53,31 e 50,33; 55,16 e 52,25; 52,22 e 49,20; e 53,39 e 50,61%, respectivamente. Assim, a LDA foi eficiente na estimativa da digestibilidade, em função de sua adequada recuperação. Os nutrientes foram utilizados de forma semelhante pelos grupos genéticos.
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Foram utilizados dados de cinqüenta e um rebanhos participantes do Programa de Melhoramento Genético da Raça Nelore (PMGRN), distribuídos nos estados de Goiás (GO), Mato Grosso do Sul (MS), Mato Grosso (MT), Minas Gerais (MG), São Paulo (SP), Maranhão (MA) e Bahia (BA). Foram obtidas estimativas de parâmetros genéticos para os pesos padronizados aos 120 (P120), 455 (P455) e 550 (P550) dias de idade. Análises unicaráter e bicaráter foram realizadas por modelo animal usando o aplicativo MTDFREML. Para P120 foi utilizado um modelo que incluiu como efeitos fixos, grupo de contemporâneos e classe de idade da vaca ao parto, e como aleatórios, os efeitos genéticos direto, materno e de ambiente permanente da vaca. Para P455 e P550, o modelo utilizado incluiu os mesmos efeitos fixos e o efeito genético direto do animal. ANas análises unicaráter, as estimativas de herdabilidade direta foram 0,29, 0,51 e 0,47 para P120, P455 e P550, respectivamente. Nas análises bicaráter, observaram-se coeficientes de herdabilidade direta de 0,50 e 0,58 para P120, 0,50 e 0,53 para P455 e 0,44 e 0,49 para P550. As correlações genéticas estimadas entre P120 e P455, P120 e P550 e P455 e P550, foram 0,92, 0,93 e 0,96, respectivamente. As estimativas de herdabilidade obtidas para P455 e as correlações genéticas deste peso com P120 e P550 sugerem que a avaliação genética pode ser feita aos 15 meses de idade em substituição aos 18 meses.