Chromosome mapping of retrotransposon AviRTE in a neotropical bird species: Trogon surrucura (Trogoniformes; Trogonidae).

Avian genomes are characterized as being more compact than other amniotes, with less diversity and density of transposable elements (TEs). In addition, birds usually show bimodal karyotypes, exhibiting a great variation in diploid numbers. Some species present unusually large sex chromosomes, possibly due to the accumulation of repetitive sequences. Avian retrotransposon-like element (AviRTE) is a long interspersed nuclear element (LINE) recently discovered in the genomes of birds and nematodes, and it is still poorly characterized in terms of chromosomal mapping and phylogenetic relationships. In this study, we mapped AviRTE isolated from the Trogon surrucura genome into the T. surrucura (TSU) karyotype. Furthermore, we analyzed the phylogenetic relationships of this LINE in birds and other vertebrates. Our results showed that the distribution pattern of AviRTE is not restricted to heterochromatic regions, with accumulation on the W chromosome of TSU, yet another species with an atypical sex chromosome and TE hybridization. The phylogenetic analysis of AviRTE sequences in birds agreed with the proposed phylogeny of species in most clades, and allowed the detection of this sequence in other species, expanding the distribution of the element.

Understanding microchromosomal organization and evolution in four representative woodpeckers (Picidae, Piciformes) through BAC-FISH analysis.

The genome organization of woodpeckers has several distinctive features e.g., an uncommon accumulation of repetitive sequences, enlarged Z chromosomes, and atypical diploid numbers. Despite the large diversity of species, there is a paucity of detailed cytogenomic studies for this group and we thus aimed to rectify this. Genome organization patterns and hence evolutionary change in the microchromosome formation of four species (Colaptes campestris, Veniliornis spilogaster, Melanerpes candidus, and Picumnus nebulosus) was established through fluorescence in situ hybridization using bacterial artificial chromosomes originally derived from Gallus gallus and Taeniopygia guttata. Findings suggest that P. nebulosus (2n = 110), which was described for the first time, had the most basal karyotype among species of Picidae studied here, and probably arose as a result of fissions of avian ancestral macrochromosomes. We defined a new chromosomal number for V. spilogaster (2n = 88) and demonstrated microchromosomal rearrangements involving C. campestris plus a single, unique hitherto undescribed rearrangement in V. spilogaster. This comprised an inversion after a fusion involving the ancestral microchromosome 12 (homologous to chicken microchromosome 12). We also determined that the low diploid number of M. candidus is related to microchromosome fusions. Woodpeckers thus exhibit significantly rearranged karyotypes compared to the putative ancestral karyotype.

Satellite DNAs, heterochromatin, and sex chromosomes of the wattled jacana (Charadriiformes; Jacanidae): a species with highly rearranged karyotype.

Charadriiformes, which comprises shorebirds and their relatives, is one of the most diverse avian orders, with over 390 species showing a wide range of karyotypes. Here, we isolated and characterized the whole collection of satellite DNAs (satDNAs) at both molecular and cytogenetic levels of one of its representative species, named the wattled jacana (Jacana jacana), a species that contains a typical ZZ/ZW sex chromosome system and a highly rearranged karyotype. In addition, we also investigate the in situ location of telomeric and microsatellite repeats. A small catalog of 11 satDNAs was identified that typically accumulated on microchromosomes and on the W chromosome. The latter also showed a significant accumulation of telomeric signals, being (GA)10 the only microsatellite with positive hybridization signals among all the 16 tested ones. These current findings contribute to our understanding of the genomic organization of repetitive DNAs in a bird species with high degree of chromosomal reorganization contrary to the majority of bird species that have stable karyotypes.

Chromosomal distribution of major rDNA and genome size variation in Belostoma angustum Lauck, B. nessimiani Ribeiro & Alecrim, and B. sanctulum Montandon (Insecta, Heteroptera, Belostomatidae).

Known as "electric-light bugs", belostomatids potentially act as agents of biological control. The Belostoma genus has holokinetic chromosomes, interspecific variation in diploid number, sex chromosome system and DNA content. Thus, the chromosomal complement, the accumulation of constitutive heterochromatin and the distribution of rDNA clusters by fluorescence in situ hybridization (FISH) in Belostoma angustum (BAN), Belostoma sanctulum (BSA), and Belostoma nessimiani (BNE) were evaluated. In addition, a comparative analysis of the DNA content of these species and B. estevezae (BES) was performed. BES has the highest Belostoma DNA content, while BSA has the lowest. BAN showed 2n = 29 + X1X2Y, while BSA and BNE had 2n = 14 + XY. BSA showed 18S rDNA markings on sex chromosomes, while BNE and BAN did on autosomes. The difference between BSA and BNE occurs because of the possible movement of the rDNA cluster in BNE. We suggest the occurrence of fusion in the autosomes of BSA and BNE, and fragmentation in the sex chromosomes in BAN. Also, the genome size of 1-2 pg represents a haploid DNA content of a common ancestor, from which the genomes of BES and BAN had evolved by gene duplication and heterochromatinization events.

Chromosomal evolution and phylogenetic considerations in cuckoos (Aves, Cuculiformes, Cuculidae).

The Cuckoos have a long history of difficult classification. The species of this order have been the subject of several studies based on osteology, behavior, ecology, morphology and molecular data. Despite this, the relationship between Cuculiformes and species of other orders remains controversial. In this work, two species of Cuculidae, Guira guira (Gmelin, 1788) and Piaya cayana (Linnaeus, 1766), were analyzed by means of comparative chromosome painting in order to study the chromosome evolution of this group and to undertake the first chromosome mapping of these species. Our results demonstrate high chromosomal diversity, with 2n = 76 in G. guira, with fission and fusion events involving ancestral syntenies, while P. cayana presented only fissions, which were responsible for the high diploid number of 2n = 90. Interestingly, there were no chromosomal rearrangements in common between these species. Our results, based on Giemsa staining, were compared with previous data for other cuckoos and also with taxa proposed as sister-groups of Cuculiformes (Otidiformes, Musophagiformes and Opisthocomiformes). Cytogenetic comparisons demonstrated that cuckoo species can be divided into at least three major groups. In addition, we found no evidence to place Cuculiformes close to the groups proposed previously as sister-groups.

Distribution of CR1-like transposable element in woodpeckers (Aves Piciformes): Z sex chromosomes can act as a refuge for transposable elements.

Birds have relatively few repetitive sequences compared to other groups of vertebrates; however, the members of order Piciformes (woodpeckers) have more of these sequences, composed mainly of transposable elements (TE). The TE most often found in birds is a retrotransposon chicken repeat 1 (CR1). Piciformes lineages were subjected to an expansion of the CR1 elements, carrying a larger fraction of transposable elements. This study compared patterns of chromosome distribution among five bird species, through chromosome mapping of the CR1 sequence and reconstructed their phylogenetic tree. We analyzed several members of Piciformes (Colaptes campestris, Colaptes melanochloros, Melanerpes candidus, and Veniliornis spilogaster), as well as Galliformes (Gallus gallus). Gallus gallus is the species with which most genomic and hence cytogenetic studies have been performed. The results showed that CR1 sequences are a monophyletic group and do not depend on their hosts. All species analyzed showed a hybridization signal by fluorescence in situ hybridization (FISH). In all species, the chromosomal distribution of CR1 was not restricted to heterochromatin regions in the macrochromosomes, principally pair 1 and the Z sex chromosome. Accumulation in the Z sex chromosomes can serve as a refuge for transposable elements. These results highlight the importance of transposable elements in host genomes and karyotype evolution.

Chromosome Painting in Neotropical Long- and Short-Tailed Parrots (Aves, Psittaciformes): Phylogeny and Proposal for a Putative Ancestral Karyotype for Tribe Arini.

: Most Neotropical Psittacidae have a diploid number of 2n = 70, and a dichotomy in chromosome patterns. Long-tailed species have biarmed macrochromosomes, while short-tailed species have telo/acrocentric macrochromosomes. However, the use of chromosome painting has demonstrated that karyotype evolution in Psittacidae includes a high number of inter/intrachromosomal rearrangements. To determine the phylogeny of long- and short-tailed species, and to propose a putative ancestral karyotype for this group, we constructed homology maps of Pyrrhura frontalis (PFR) and Amazona aestiva (AAE), belonging to the long- and short-tailed groups, respectively. Chromosomes were analyzed by conventional staining and fluorescent in situ hybridization using whole chromosome paints of Gallus gallus and Leucopternis albicollis. Conventional staining showed a karyotype with 2n = 70 in both species, with biarmed macrochromosomes in PFR and telo/acrocentric chromosomes in AAE. Comparison of the results with the putative avian ancestral karyotype (PAK) showed fusions in PFR of PAK1p/PAK4q (PFR1) and PAK6/PAK7 (PFR6) with a paracentric inversion in PFR6. However, in AAE, there was only the fusion between PAK6/7 (AAE7) with a paracentric inversion. Our results indicate that PFR retained a more basal karyotype than long-tailed species previously studied, and AAE a more basal karyotype for Neotropical Psittacidae analyzed so far.

Comparative chromosome painting in Columbidae (Columbiformes) reinforces divergence in Passerea and Columbea.

Pigeons and doves (Columbiformes) are one of the oldest and most diverse extant lineages of birds. However, the karyotype evolution within Columbiformes remains unclear. To delineate the synteny-conserved segments and karyotypic differences among four Columbidae species, we used chromosome painting from Gallus gallus (GGA, 2n = 78) and Leucopternis albicollis (LAL, 2n = 68). Besides that, a set of painting probes for the eared dove, Zenaida auriculata (ZAU, 2n = 76), was generated from flow-sorted chromosomes. Chromosome painting with GGA and ZAU probes showed conservation of the first ten ancestral pairs in Z. auriculata, Columba livia, and Columbina picui, while in Leptotila verreauxi, fusion of the ancestral chromosomes 6 and 7 was observed. However, LAL probes revealed a complex reorganization of ancestral chromosome 1, involving paracentric and pericentric inversions. Because of the presence of similar intrachromosomal rearrangements in the chromosomes corresponding to GGA1q in the Columbidae and Passeriformes species but without a common origin, these results are consistent with the recent proposal of divergence within Neoaves (Passerea and Columbea). In addition, inversions in chromosome 2 were identified in C. picui and L. verreauxi. Thus, in four species of distinct genera of the Columbidae family, unique chromosomal rearrangements have occurred during karyotype evolution, confirming that despite conservation of the ancestral syntenic groups, these chromosomes have been modified by the occurrence of intrachromosomal rearrangements.

Repetitive DNAs and shrink genomes: A chromosomal analysis in nine Columbidae species (Aves, Columbiformes)

Abstract An extensive karyotype variation is found among species belonging to the Columbidae family of birds (Columbiformes), both in diploid number and chromosomal morphology. Although clusters of repetitive DNA sequences play an important role in chromosomal instability, and therefore in chromosomal rearrangements, little is known about their distribution and amount in avian genomes. The aim of this study was to analyze the distribution of 11 distinct microsatellite sequences, as well as clusters of 18S rDNA, in nine different Columbidae species, correlating their distribution with the occurrence of chromosomal rearrangements. We found 2n values ranging from 76 to 86 and nine out of 11 microsatellite sequences showed distinct hybridization signals among the analyzed species. The accumulation of microsatellite repeats was found preferentially in the centromeric region of macro and microchromosomes, and in the W chromosome. Additionally, pair 2 showed the accumulation of several microsatellites in different combinations and locations in the distinct species, suggesting the occurrence of intrachromosomal rearrangements, as well as a possible fission of this pair in Geotrygon species. Therefore, although birds have a smaller amount of repetitive sequences when compared to other Tetrapoda, these seem to play an important role in the karyotype evolution of these species.

Repetitive DNAs and shrink genomes: A chromosomal analysis in nine Columbidae species (Aves, Columbiformes).

An extensive karyotype variation is found among species belonging to the Columbidae family of birds (Columbiformes), both in diploid number and chromosomal morphology. Although clusters of repetitive DNA sequences play an important role in chromosomal instability, and therefore in chromosomal rearrangements, little is known about their distribution and amount in avian genomes. The aim of this study was to analyze the distribution of 11 distinct microsatellite sequences, as well as clusters of 18S rDNA, in nine different Columbidae species, correlating their distribution with the occurrence of chromosomal rearrangements. We found 2n values ranging from 76 to 86 and nine out of 11 microsatellite sequences showed distinct hybridization signals among the analyzed species. The accumulation of microsatellite repeats was found preferentially in the centromeric region of macro and microchromosomes, and in the W chromosome. Additionally, pair 2 showed the accumulation of several microsatellites in different combinations and locations in the distinct species, suggesting the occurrence of intrachromosomal rearrangements, as well as a possible fission of this pair in Geotrygon species. Therefore, although birds have a smaller amount of repetitive sequences when compared to other Tetrapoda, these seem to play an important role in the karyotype evolution of these species.

Chromosome Painting in Trogon s. surrucura (Aves, Trogoniformes) Reveals a Karyotype Derived by Chromosomal Fissions, Fusions, and Inversions.

Trogons are forest birds with a wide distribution, being found in Africa, Asia, and America, and are included in the order Trogoniformes, family Trogonidae. Phylogenetic studies using molecular data have not been able to determine the phylogenetic relationship among the different genera of trogons. So far, no cytogenetic data for these birds exist. Hence, the aim of this study was to characterize the karyotype of Trogon surrucura surrucura by means of classical and molecular cytogenetics. We found a diploid chromosome number of 2n = 82, similar to most birds, with several derived features compared to chicken and the putative ancestral avian karyotype. T. s. surrucura showed 3 pairs of microchromosomes bearing 18S rDNA clusters. The Z and W sex chromosomes were of similar size but could readily be identified by morphological differences. Using chromosome painting with whole chromosome probes from Gallus gallus and Leucopternis albicollis, we found that the chromosomes homologous to chicken chromosomes 2 and 5 correspond to 2 different pairs in T. s. surrucura and L. albicollis, due to the occurrence of centric fissions. Paracentric inversions were detected in the segment homologous to chicken chromosome 1q, and we confirmed the recurrence of breakpoints when our results were compared to other species of birds already analyzed by FISH or by in silico genome assembly.

Intrachromosomal rearrangements in two representatives of the genus Saltator (Thraupidae, Passeriformes) and the occurrence of heteromorphic Z chromosomes.

Saltator is a genus within family Thraupidae, the second largest family of Passeriformes, with more than 370 species found exclusively in the New World. Despite this, only a few species have had their karyotypes analyzed, most of them only with conventional staining. The diploid number is close to 80, and chromosome morphology is similar to the usual avian karyotype. Recent studies using cross-species chromosome painting have shown that, although the chromosomal morphology and number are similar to many species of birds, Passeriformes exhibit a complex pattern of paracentric and pericentric inversions in the chromosome homologous to GGA1q in two different suborders, Oscines and Suboscines. Hence, considering the importance and species richness of Thraupidae, this study aims to analyze two species of genus Saltator, the golden-billed saltator (S. aurantiirostris) and the green-winged saltator (S. similis) by means of classical cytogenetics and cross-species chromosome painting using Gallus gallus and Leucopternis albicollis probes, and also 5S and 18S rDNA and telomeric sequences. The results show that the karyotypes of these species are similar to other species of Passeriformes. Interestingly, the Z chromosome appears heteromorphic in S. similis, varying in morphology from acrocentric to metacentric. 5S and 18S probes hybridize to one pair of microchromosomes each, and telomeric sequences produce signals only in the terminal regions of chromosomes. FISH results are very similar to the Passeriformes already analyzed by means of molecular cytogenetics (Turdus species and Elaenia spectabilis). However, the paracentric and pericentric inversions observed in Saltator are different from those detected in these species, an observation that helps to explain the probable sequence of rearrangements. As these rearrangements are found in both suborders of Passeriformes (Oscines and Suboscines), we propose that the fission of GGA1 and inversions in GGA1q have occurred very early after the radiation of this order.

Chromosome Painting in Vanellus chilensis: Detection of a Fusion Common to Clade Charadrii (Charadriiformes).

The Southern lapwing (Vanellus chilensis) is endemic to America and is well-known because of the vast expansion of its geographical distribution and its involvement in air accidents. Despite its popularity, there is no information concerning the genomic organization and karyotype of this species. Hence, because other species of the genus Vanellus have variable diploid numbers from 2n = 58 to 76, the aim of this report was to analyze the karyotype of V. chilensis by means of classical and molecular cytogenetics. We found that 2n = 78 and chromosome painting using probes of Gallus gallus (GGA) and Leucopternis albicollis revealed an organization similar to the avian putative ancestral karyotype, except for the fusion of GGA7 and GGA8, also found in Burhinus oedicnemus, the only Charadriiforme species analyzed by FISH so far. This rearrangement may represent a cytogenetic signature for this group and, in addition, must be responsible for the difference between the diploid number found in the avian putative ancestral karyotype (2n = 80) and V. chilensis (2n = 78).

Inferência bayesiana aplicada à estimação de herdabilidades dos parâmetros da curva de crescimento de fêmeas da raça Nelore

The objective of this study was to estimate genetic parameters using Bayesian inference for the estimates of individual parameters of mature weight (Â) and growth rate ( img border=0 width=32 height=32 id="_x0000_i1030" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">), obtained by Brody growth function. The file consisted of 14,563 records relating to weights and ages of 1,158 Nelore females, participants in the Genetic Improvement Program of the Nellore. For the estimates analysis of the curve parameters via Bayesian inference, it was used an univariated animal model that included as fixed effect of contemporary group (animals born on the same state, in the same quarter of the year, the same year and feedlot) and random as the direct genetic and residual. In this analysis it was used two different sizes for the chains generated by Gibbs sampling algorithm, 550 and 1.1 million cycles, with initial discarding of 50 000 and sample of 100 000 cycles, respectively, and sampled every 500 cycles and 1000, respectively. The mean posterior and residual additive genetic variance showed a small variation to both  and img border=0 width=32 height=32 id="_x0000_i1031" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">, even when implemented in different sizes for the chains generated by Gibbs sampling algorithm. The heritability estimates for Â, ranged from 0.44 to 0.46, similar to the range 0.46 to 0.48 obtained for the estimates of img border=0 width=32 height=32 id="_x0000_i1032" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">. These magnitudes indicate that the selection can be used as a tool to change the shape of the growth curve of these animals. However, the use of the information to amend the growth curve of animals, must be done with great care, since the traits to be worked in the modification of the shape of the growth curve according to the literature results are negatively correlated.

Objetivou-se estimar parâmetros genéticos, utilizando inferência Bayesiana, para as estimativas dos parâmetros individuais de peso à maturidade (Â) e taxa de crescimento ( img border=0 width=32 height=32 id="_x0000_i1026" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">), obtidos pela função de crescimento Brody. O arquivo estava constituído de 14.563 registros de pesos e idades referentes a 1.158 fêmeas da raça Nelore, participantes do Programa de Melhoramento Genético da Raça Nelore. Para a análise das estimativas dos parâmetros da curva, via inferência bayesiana, foi proposto um modelo animal unicaráter, que incluiu como fixo o efeito de grupo contemporâneo (animais nascidos no mesmo estado, no mesmo trimestre do ano, mesmo ano e mesmo regime alimentar) e como aleatórios os efeitos genético direto e residual. Nessa análise, foram utilizados dois diferentes tamanhos para as cadeias geradas pelo algoritmo de amostragem de Gibbs, de 550 e 1.100 mil ciclos, com períodos de descarte amostral de 50 e 100 mil ciclos, respectivamente, e amostragens a cada 500 e 1.000 ciclos, respectivamente. As médias posteriores da variância genética aditiva e residual foram próximas, tanto para  quanto para a img border=0 width=32 height=32 id="_x0000_i1027" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">, mesmo quando implementados diferentes tamanhos para as cadeias geradas pelo algoritmo de amostragem de Gibbs. Os coeficientes de herdabilidade estimados para Â, variaram de 0,44 a 0,46, amplitude semelhante aos 0,46 a 0,48 obtidos para as estimativas de img border=0 width=32 height=32 id="_x0000_i1028" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">. Essas magnitudes indicam que a seleção pode ser usada como instrumento para alterar a forma da curva de crescimento desses animais. Entretanto, o uso das informações obtidas, visando à alteração da curva de crescimento dos animais, deve ser feito com grande cautela, uma vez que as características a serem trabalhadas na modificação do formato da curva de crescimento, de acordo com resultados da literatura especializada, são negativamente correlacionadas.

Inferência bayesiana aplicada à estimação de herdabilidades dos parâmetros da curva de crescimento de fêmeas da raça Nelore

The objective of this study was to estimate genetic parameters using Bayesian inference for the estimates of individual parameters of mature weight (Â) and growth rate ( img border=0 width=32 height=32 id="_x0000_i1030" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">), obtained by Brody growth function. The file consisted of 14,563 records relating to weights and ages of 1,158 Nelore females, participants in the Genetic Improvement Program of the Nellore. For the estimates analysis of the curve parameters via Bayesian inference, it was used an univariated animal model that included as fixed effect of contemporary group (animals born on the same state, in the same quarter of the year, the same year and feedlot) and random as the direct genetic and residual. In this analysis it was used two different sizes for the chains generated by Gibbs sampling algorithm, 550 and 1.1 million cycles, with initial discarding of 50 000 and sample of 100 000 cycles, respectively, and sampled every 500 cycles and 1000, respectively. The mean posterior and residual additive genetic variance showed a small variation to both  and img border=0 width=32 height=32 id="_x0000_i1031" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">, even when implemented in different sizes for the chains generated by Gibbs sampling algorithm. The heritability estimates for Â, ranged from 0.44 to 0.46, similar to the range 0.46 to 0.48 obtained for the estimates of img border=0 width=32 height=32 id="_x0000_i1032" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">. These magnitudes indicate that the selection can be used as a tool to change the shape of the growth curve of these animals. However, the use of the information to amend the growth curve of animals, must be done with great care, since the traits to be worked in the modification of the shape of the growth curve according to the literature results are negatively correlated.

Objetivou-se estimar parâmetros genéticos, utilizando inferência Bayesiana, para as estimativas dos parâmetros individuais de peso à maturidade (Â) e taxa de crescimento ( img border=0 width=32 height=32 id="_x0000_i1026" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">), obtidos pela função de crescimento Brody. O arquivo estava constituído de 14.563 registros de pesos e idades referentes a 1.158 fêmeas da raça Nelore, participantes do Programa de Melhoramento Genético da Raça Nelore. Para a análise das estimativas dos parâmetros da curva, via inferência bayesiana, foi proposto um modelo animal unicaráter, que incluiu como fixo o efeito de grupo contemporâneo (animais nascidos no mesmo estado, no mesmo trimestre do ano, mesmo ano e mesmo regime alimentar) e como aleatórios os efeitos genético direto e residual. Nessa análise, foram utilizados dois diferentes tamanhos para as cadeias geradas pelo algoritmo de amostragem de Gibbs, de 550 e 1.100 mil ciclos, com períodos de descarte amostral de 50 e 100 mil ciclos, respectivamente, e amostragens a cada 500 e 1.000 ciclos, respectivamente. As médias posteriores da variância genética aditiva e residual foram próximas, tanto para  quanto para a img border=0 width=32 height=32 id="_x0000_i1027" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">, mesmo quando implementados diferentes tamanhos para as cadeias geradas pelo algoritmo de amostragem de Gibbs. Os coeficientes de herdabilidade estimados para Â, variaram de 0,44 a 0,46, amplitude semelhante aos 0,46 a 0,48 obtidos para as estimativas de img border=0 width=32 height=32 id="_x0000_i1028" src="../../../../../../img/revistas/cr/2013nahead/a11813img06.gif">. Essas magnitudes indicam que a seleção pode ser usada como instrumento para alterar a forma da curva de crescimento desses animais. Entretanto, o uso das informações obtidas, visando à alteração da curva de crescimento dos animais, deve ser feito com grande cautela, uma vez que as características a serem trabalhadas na modificação do formato da curva de crescimento, de acordo com resultados da literatura especializada, são negativamente correlacionadas.

Classical nonlinear models to describe the growth curve for Murrah buffalo breed

With the objective of to adjust nonlinear models for the growth curves for a buffaloes herd raised in floodable lands in Rio Grande do Sul state, monthly records measured from birth to two years-old of 64 males and 63 females born between 1982 and 1989 were used. The models used were: Von Bertalanffy, Brody, Gompertz and Logistic. The parameters were estimated by NLIN procedure and the criteria used to evaluate the adjustment given by the models were: asymptotic standard deviation; coefficient of determination; average absolute deviation of residues and asymptotic index. Von Bertalanffy and Brody models overestimated the male asymptotic weight (A) in 15.9 and 171.3kg, respectively, and the Gompertz and Logistic models underestimated it in 4.5 and 13.4kg, respectively. For females, the Logistic model underestimated the asymptotic weight (-2.09kg), and Gompertz, Von Bertalanffy and Brody overestimated this parameter in 8.04, 17.7, and 280.33kg, respectively. The biggest average deviation was estimated by Brody model for both sexes, characterizing the biggest index. Considering the criteria, it is recommended the Gompertz and Logistic models for adjust females and males Murrah buffaloes breed growth curves.

Com o objetivo de ajustar modelos não-lineares ao crescimento ponderal para búfalos criados em terras baixas no Estado do Rio Grande do Sul, foram utilizados registros mensais mensurados do nascimento aos dois anos de idade de 64 machos e 63 fêmeas, nascidos no período de 1982 a 1989. Utilizaram-se os modelos: Von Bertalanffy, Brody, Gompertz e Logístico. Os parâmetros foram estimados usando o procedimento NLIN e os critérios utilizados para verificar o ajuste dos modelos foram: desvio padrão assintótico; coeficiente de determinação; desvio médio absoluto dos resíduos e o índice assintótico. Os modelos Von Bertalanffy e Brody superestimaram o peso assintótico (A) para os machos em 15,9 e 171,3kg, respectivamente, e os modelos Gompertz e Logístico, subestimaram em 4,5 e 13,4kg, respectivamente. Para as fêmeas, o modelo Logístico subestimou o peso assintótico (-2,09kg) e os modelos Gompertz, Von Bertalanffy e Brody superestimaram esse parâmetro em: 8,04; 17,7 e 280,33kg, respectivamente. O maior desvio médio absoluto foi estimado pelo modelo Brody para ambos os sexos, caracterizando o melhor índice. Considerando os critérios, recomenda-se o modelo Gompertz e o modelo Logístico para ajustar a curva de crescimento de fêmeas e machos da raça Murrah.

Classical nonlinear models to describe the growth curve for Murrah buffalo breed

With the objective of to adjust nonlinear models for the growth curves for a buffaloes herd raised in floodable lands in Rio Grande do Sul state, monthly records measured from birth to two years-old of 64 males and 63 females born between 1982 and 1989 were used. The models used were: Von Bertalanffy, Brody, Gompertz and Logistic. The parameters were estimated by NLIN procedure and the criteria used to evaluate the adjustment given by the models were: asymptotic standard deviation; coefficient of determination; average absolute deviation of residues and asymptotic index. Von Bertalanffy and Brody models overestimated the male asymptotic weight (A) in 15.9 and 171.3kg, respectively, and the Gompertz and Logistic models underestimated it in 4.5 and 13.4kg, respectively. For females, the Logistic model underestimated the asymptotic weight (-2.09kg), and Gompertz, Von Bertalanffy and Brody overestimated this parameter in 8.04, 17.7, and 280.33kg, respectively. The biggest average deviation was estimated by Brody model for both sexes, characterizing the biggest index. Considering the criteria, it is recommended the Gompertz and Logistic models for adjust females and males Murrah buffaloes breed growth curves.

Com o objetivo de ajustar modelos não-lineares ao crescimento ponderal para búfalos criados em terras baixas no Estado do Rio Grande do Sul, foram utilizados registros mensais mensurados do nascimento aos dois anos de idade de 64 machos e 63 fêmeas, nascidos no período de 1982 a 1989. Utilizaram-se os modelos: Von Bertalanffy, Brody, Gompertz e Logístico. Os parâmetros foram estimados usando o procedimento NLIN e os critérios utilizados para verificar o ajuste dos modelos foram: desvio padrão assintótico; coeficiente de determinação; desvio médio absoluto dos resíduos e o índice assintótico. Os modelos Von Bertalanffy e Brody superestimaram o peso assintótico (A) para os machos em 15,9 e 171,3kg, respectivamente, e os modelos Gompertz e Logístico, subestimaram em 4,5 e 13,4kg, respectivamente. Para as fêmeas, o modelo Logístico subestimou o peso assintótico (-2,09kg) e os modelos Gompertz, Von Bertalanffy e Brody superestimaram esse parâmetro em: 8,04; 17,7 e 280,33kg, respectivamente. O maior desvio médio absoluto foi estimado pelo modelo Brody para ambos os sexos, caracterizando o melhor índice. Considerando os critérios, recomenda-se o modelo Gompertz e o modelo Logístico para ajustar a curva de crescimento de fêmeas e machos da raça Murrah.

GENETIC PARAMETERS AND REPRODUCTIVE AND PRODUCTIVE CHARACTERISTICS / PARÂMETROS GENÉTICOS DE CARACTERÍSTICAS PRODUTIVAS E REPRODUTIVAS EM ZEBUÍNOS DE CORTE (REVISÃO)

Developments in cattle raising and the need to sidered: birth weight (BW), _20 days (W_20), weaning make herds commercially enhanced have intensified the weight (W205), yearling weight (YW) and postyearling efforts to identify animals that grow and reproduce at ear-(PW), and the reproductive ones: yearling scrotal circunlier ages. In an attempt to facilitate research, through the ference (YSC) and postyearling (PSC) and age at first compilation and analysis of results for estimated genetic calving (AFC).The average estimates for direct, maternal parameters for productive and reproductive traits in zebu and total heritability were, respectively: 0.33; 0.09 and beef breeds, 67 publications were analyzed from both Na-0.27 (BW), 0.27; 0.08 and 0.2_ (W_20), 0.28; 0._2 and tional and international journals in the fields of Animal 0.24 (WW), 0.3_; 0._0 and 0.26 (YW), 0.35; 0.05 and Science/Fishing Resources between _995 and 2005, all of 0._8 (PW). Nearly 70% of all articles were published in which are rated A or B by the QUALIS program (2005) journals rated A, with international circulation, and 78% at CAPESs Portal. The productive traits had been con-concern the Nelore breed. KEY WORDS: Age at first calving, genetic correlation, heritability, scrotal circumference, weights.

O desenvolvimento da pecuária e a necessidade de _20 dias (P_20), desmame (P205), ano (PA) e sobreano melhorar o rebanho comercialmente intensificaram os esfor-(PSA), e as reprodutivas: perímetro escrotal ao ano (PEA) ços para a identificação de animais com maior precocidade e sobreano (PESA) e idade ao primeiro parto (IPP). As de crescimento e reprodução. Com o objetivo de facilitar a médias para as estimativas de herdabilidade direta, materna pesquisa, reunindo e discutindo resultados de estimativas e total foram respectivamente: 0,33, 0,09, 0,27 (PN); 0,27, de parâmetros genéticos das raças zebuínas de corte para 0,08, 0,2_ (P_20); 0,28, 0,_2, 0,24 (P205); 0,3_, 0,_0, 0,26 características produtivas e reprodutivas analisaram-se (P365); 0,35, 0,05, 0,_8 (PSA). As estimativas médias de 67 trabalhos publicados de _995 a 2005, em periódicos herdabilidade direta para as características reprodutivas nacionais e internacionais, classificados pelo programa foram: 0,50 (PE365); 0,46 (PE550) e 0,_6 (IPP). Aproxi-QUALIS (2006) do Portal da CAPES como A, B e C na madamente 70% dos artigos publicados são de periódicos área de Zootecnia/Recursos Pesqueiros. As características classificados como A e de circulação internacional e 78% produtivas consideradas foram: peso ao nascimento (PN), são relativos à raça Nelore. PALAVRAS-CHAVE: Correlação genética, herdabilidade, idade ao primeiro part

Genetic parameters and reproductive and productive characteristics / Parâmetros genéticos de características produtivas e reprodutivas em zebuínos de corte (revisão)

Developments in cattle raising and the need to sidered: birth weight (BW), _20 days (W_20), weaning make herds commercially enhanced have intensified the weight (W205), yearling weight (YW) and postyearling efforts to identify animals that grow and reproduce at ear-(PW), and the reproductive ones: yearling scrotal circunlier ages. In an attempt to facilitate research, through the ference (YSC) and postyearling (PSC) and age at first compilation and analysis of results for estimated genetic calving (AFC).The average estimates for direct, maternal parameters for productive and reproductive traits in zebu and total heritability were, respectively: 0.33; 0.09 and beef breeds, 67 publications were analyzed from both Na-0.27 (BW), 0.27; 0.08 and 0.2_ (W_20), 0.28; 0._2 and tional and international journals in the fields of Animal 0.24 (WW), 0.3_; 0._0 and 0.26 (YW), 0.35; 0.05 and Science/Fishing Resources between _995 and 2005, all of 0._8 (PW). Nearly 70% of all articles were published in which are rated A or B by the QUALIS program (2005) journals rated A, with international circulation, and 78% at CAPESs Portal. The productive traits had been con-concern the Nelore breed. KEY WORDS: Age at first calving, genetic correlation, heritability, scrotal circumference, weights.

O desenvolvimento da pecuária e a necessidade de _20 dias (P_20), desmame (P205), ano (PA) e sobreano melhorar o rebanho comercialmente intensificaram os esfor-(PSA), e as reprodutivas: perímetro escrotal ao ano (PEA) ços para a identificação de animais com maior precocidade e sobreano (PESA) e idade ao primeiro parto (IPP). As de crescimento e reprodução. Com o objetivo de facilitar a médias para as estimativas de herdabilidade direta, materna pesquisa, reunindo e discutindo resultados de estimativas e total foram respectivamente: 0,33, 0,09, 0,27 (PN); 0,27, de parâmetros genéticos das raças zebuínas de corte para 0,08, 0,2_ (P_20); 0,28, 0,_2, 0,24 (P205); 0,3_, 0,_0, 0,26 características produtivas e reprodutivas analisaram-se (P365); 0,35, 0,05, 0,_8 (PSA). As estimativas médias de 67 trabalhos publicados de _995 a 2005, em periódicos herdabilidade direta para as características reprodutivas nacionais e internacionais, classificados pelo programa foram: 0,50 (PE365); 0,46 (PE550) e 0,_6 (IPP). Aproxi-QUALIS (2006) do Portal da CAPES como A, B e C na madamente 70% dos artigos publicados são de periódicos área de Zootecnia/Recursos Pesqueiros. As características classificados como A e de circulação internacional e 78% produtivas consideradas foram: peso ao nascimento (PN), são relativos à raça Nelore. PALAVRAS-CHAVE: Correlação genética, herdabilidade, idade ao primeiro part

Estimativas de parâmetros genéticos para características incluídas em critérios de seleção em gado Nelore

Records of animals from 20 herds participating in the Genetic Breeding Program of Nelore Cattle (PMGRN) were analyzed. The variables considered were gains by day of age until 120, 200, 310 and 350kg (WGD weight k), the adjusted weights at 120, 240, 365 and 550 days and the observed weights at these same ages. Animal Model analysis using MTDFREML programs showed similar heritabilities for pre-weaning weights ranging from 0.21 to 0.27 for direct effect. The genetic correlation between direct and maternal effects was negative and ranged from -0.42 to -0.24. For postweaning weights the heritabilities were greater for the adjusted and observed weights then for the daily gain by age. The genetic correlation showed the same tendency for the first two kinds of traits and was positive and close to zero for the last one. The contribution of additive maternal effect and permanent environmental effect to the phenotypic variance of most traits studied should be considered in breeding programs of Nelore cattle. Results suggested that selection for postweaning traits would be more efficient when done on weights than on WGD.

Foram analisados registros de 20 rebanhos integrantes do Programa de Melhoramento Genético da Raça Nelore (PMGRN), estudando-se as seguintes variáveis: ganho de peso por dia de idade até os 120, 200, 310 e 350kg (GPDpesok), peso padrão aos 120, 240, 365 e 550 dias de idade e peso real às idades mencionadas. As análises unicaráter mediante Modelo Animal, usando o aplicativo MTDFREML, proporcionaram estimativas de herdabilidades semelhantes para os pesos pré-desmama, variando entre 0,21-0,27 para o efeito direto, sendo que a correlação genética entre efeitos diretos e maternos foi negativa, variando entre -0,42 a -0,24. Para os pesos pós-desmama os coeficientes de herdabilidade foram maiores para as variáveis pesos padrão e peso real do que em relação ao ganho de peso por dia de idade. A correlação genética mostrou a mesma tendência para os dois primeiros tipos de características e, para última, foi positiva e próxima de zero. A contribuição do efeito aditivo materno e do ambiente permanente para a variância fenotípica na maioria das características estudadas justificam sua inclusão em programas de Melhoramento genético na raça Nelore. Os resultados indicam que, para o período pós-desmama, a seleção por peso seria mais eficiente do que para o GPD.