Abstract We aimed to evaluate the effects of paternal genotypes (Piau, Duroc-based, and Pietrain) and nutritional plans with different digestible lysine contents (Low, Medium, and High) on performance, carcass, and meat quality traits of pigs. Pietrain and Duroc crossbred barrows and gilts were similar in performance and carcass traits and had the greatest values when compared to Piau crossbred pigs. Regarding meat quality, drip loss was greater in pork from Pietrain crossbred barrows and gilts compared to Duroc and Piau crossbred pigs. The High nutritional plan had the greatest daily digestible lysine intake value, followed by the Medium and Low nutritional plans. Most of the performance, carcass, and meat quality traits that were evaluated in barrows and gilts were not affected by the nutritional plans. In general, Duroc and Pietrain crossbred pigs had a greater performance and carcass yield when compared to Piau crossbred pigs.

Resumo: O objetivo deste trabalho foi avaliar o uso da regressão quantílica regularizada (RQR) para predição do mérito genético em suínos quanto a características assimétricas de carcaça, em comparação ao método do lasso bayesiano (Blasso). Foram utilizados dados genéticos das características rendimento de carcaça, espessura de bacon e espessura de toucinho de uma população F2 composta por 345 indivíduos, obtida pelo cruzamento de animais da raça Piau com os de raça comercial. A RQR foi avaliada tendo-se considerado diferentes quantis (τ = 0,05 a 0,95). O modelo de RQR utilizado para estimar o mérito genético apresentou acurácias maiores ou iguais àquelas obtidas pelo Blasso, para todas as características estudadas. Houve incremento de 6,7 e 20,0% na acurácia, quando se consideraram os quantis 0,15 e 0,45 na avaliação do rendimento de carcaça e da espessura de bacon, respectivamente. Os resultados obtidos são indicativos de que a regressão quantílica regularizada apresenta maior acurácia que o método lasso Bayesiano para predição do mérito genético de variáveis assimétricas de carcaça.

Abstract: The objective of this work was to evaluate the use of regularized quantile regression (RQR) to predict the genetic merit of pigs for asymmetric carcass traits, compared with the Bayesian lasso (Blasso) method. The genetic data of the traits carcass yield, bacon thickness, and backfat thickness from a F2 population composed of 345 individuals, generated by crossing animals from the Piau breed with those of a commercial breed, were used. RQR was evaluated considering different quantiles (τ = 0.05 to 0.95). The RQR model used to estimate the genetic merit showed accuracies higher than or equal to those obtained by Blasso, for all studies traits. There was an increase of 6.7 and 20.0% in accuracy when the quantiles 0.15 and 0.45 were considered in the evaluation of carcass yield and bacon thickness, respectively. The obtained results are indicative that the regularized quantile regression presents higher accuracy than the Bayesian lasso method for the prediction of the genetic merit of pigs for asymmetric carcass variables.

ABSTRACT: Genome association analyses have been successful in identifying quantitative trait loci (QTLs) for pig body weights measured at a single age. However, when considering the whole weight trajectories over time in the context of genome association analyses, it is important to look at the markers that affect growth curve parameters. The easiest way to consider them is via the two-step method, in which the growth curve parameters and marker effects are estimated separately, thereby resulting in a reduction of the statistical power and the precision of estimates. One efficient solution is to adopt nonlinear mixed models (NMM), which enables a joint modeling of the individual growth curves and marker effects. Our aim was to propose a genome association analysis for growth curves in pigs based on NMM as well as to compare it with the traditional two-step method. In addition, we also aimed to identify the nearest candidate genes related to significant SNP (single nucleotide polymorphism) markers. The NMM presented a higher number of significant SNPs for adult weight (A) and maturity rate (K), and provided a direct way to test SNP significance simultaneously for both the A and K parameters. Furthermore, all significant SNPs from the two-step method were also reported in the NMM analysis. The ontology of the three candidate genes (SH3BGRL2, MAPK14, and MYL9) derived from significant SNPs (simultaneously affecting A and K) allows us to make inferences with regards to their contribution to the pig growth process in the population studied.

RESUMO: A principal contribuição da seleção genômica (SG) é a identificação de animais geneticamente superiores para características de difícil mensuração e/ou avaliadas tardiamente nos animais, tal como o pH da carne suína. Na SG, uma vez que o número de marcadores é geralmente maior que o número de animais genotipados, e tais marcadores são altamente correlacionados (devido ao desequilíbrio de ligação), métodos estatísticos baseados na redução de dimensionalidade têm sido propostos. Dentre estes, destaca-se o Quadrados Mínimos Parciais (PLS) pela simplicidade e alta acurácia de predição. Porém, a determinação do número ótimo de componentes a ser utilizado no PLS ainda se caracteriza como um desafio para a aplicação do método. Assim, objetivou-se aplicar o PLS (e também regressões em componentes principais e a múltipla tradicional) na SG para pH da carne suína (medido aos 45min e às 24 horas após o abate), bem como identificar o número ótimo de componentes por meio dos métodos do grau de liberdade (GL) e validação cruzada (VC). O primeiro é baseado na Teoria de Informação Estatística e VC é empírica e fundamentada em amostras independentes do arquivo original. O PLS superou os demais métodos de regressão, fornecendo predições satisfatórias quando utilizadas apenas informações genotípicas (painel de SNP de baixa densidade). Além disso, os efeitos dos SNPs estimados via PLS possibilitaram identificar uma região relevante no cromossomo 4 que pode influenciar as características estudadas. Os métodos GL e VC foram similares quanto à determinação do número ótimo de componentes na análise PLS, porém o método GL pode ser recomendado devido a sua maior fundamentação estatística.

ABSTRACT: The main application of genomic selection (GS) is the early identification of genetically superior animals for traits difficult-to-measure or lately evaluated, such as meat pH (measured after slaughter). Because the number of markers in GS is generally larger than the number of genotyped animals and these markers are highly correlated owing to linkage disequilibrium, statistical methods based on dimensionality reduction have been proposed. Among them, the partial least squares (PLS) technique stands out, because of its simplicity and high predictive accuracy. However, choosing the optimal number of components remains a relevant issue for PLS applications. Thus, we applied PLS (and principal component and traditional multiple regression) techniques to GS for pork pH traits (with pH measured at 45min and 24h after slaughter) and also identified the optimal number of PLS components based on the degree-of-freedom (DoF) and cross-validation (CV) methods. The PLS method out performs the principal component and traditional multiple regression techniques, enabling satisfactory predictions for pork pH traits using only genotypic data (low-density SNP panel). Furthermore, the SNP marker estimates from PLS revealed a relevant region on chromosome 4, which may affect these traits. The DoF and CV methods showed similar results for determining the optimal number of components in PLS analysis; thus, from the statistical viewpoint, the DoF method should be preferred because of its theoretical background (based on the "statistical information theory"), whereas CV is an empirical method based on computational effort.

Abstract This study used qRT-PCR to examine variation in the expression of 13 myogenes during muscle development in four prenatal periods (21, 40, 70 and 90 days post-insemination) in commercial (the three-way Duroc, Landrace and Large-White cross) and local Piau pig breeds that differ in muscle mass. There was no variation in the expression of the CHD8, EID2B, HIF1AN, IKBKB, RSPO3, SOX7 and SUFU genes at the various prenatal ages or between breeds. The MAP2K1 and RBM24 genes showed similar expression between commercial and Piau pigs but greater expression (p < 0.05) in at least one prenatal period. Pair-wise comparisons of prenatal periods in each breed showed that only the CSRP3, LEF1, MRAS and MYOG genes had higher expression (p < 0.05) in at least one prenatal period in commercial and Piau pigs. Overall, these results identified the LEF1 gene as a primary candidate to account for differences in muscle mass between the pig breeds since activation of this gene may lead to greater myoblast fusion in the commercial breed compared to Piau pigs. Such fusion could explain the different muscularity between breeds in the postnatal periods.

O objetivo deste trabalho foi avaliar o efeito de dietas com diferentes concentrações de fósforo disponível sobre o perfil metabólico e o peso corporal de leitões em fase inicial de crescimento, mantidos em ambientes térmicos distintos. Foram utilizados 120 leitões machos castrados, de linhagem comercial e com peso corporal médio de 15 kg. Os tratamentos consistiram de dietas com 0,107, 0,214, 0,321, 0,428 e 0,535% de fósforo disponível, e de dois ambientes: termoneutro e quente. O peso corporal foi determinado no início e no final da fase experimental, e amostras de sangue foram coletadas para a medição de eletrólitos, albumina, proteína total, substâncias nitrogenadas, fosfatase alcalina total e óssea, hormônios tireoidianos, glicose e lactato. Tanto as dietas quanto os ambientes produziram efeito sobre o ganho de peso corporal e sobre os valores de sódio, potássio, cálcio total, magnésio, fósforo, fosfatase alcalina total e óssea, T4 livre e lactato. O aumento nos teores de fósforo na dieta tem efeito positivo sobre o peso corporal, nos ambientes estudados, mas desequilibra as relações sanguíneas cálcio:fósforo. O estresse por calor diminui as concentrações de glicose, fosfatase alcalina total e T4 livre no sangue, e aumenta as de lactato. Parâmetros bioquímicos sanguíneos retratam o estado metabólico dos animais e podem ser usados para avaliação do balanço nutricional e para detecção precoce de alterações metabólicas.

The objective of this work was to evaluate the effect of diets with different available phosphorus contents on metabolic profile and on body weight of piglets at baseline, maintained in distinct thermal environments. One hundred and twenty barrow piglets from commercial strain and with an average body weight of 15 kg were used. The treatments consisted of diets with 0.107, 0.214, 0.321, 0.428, and 0.535% available phosphorus, and of two environments: thermoneutral and warm. Body weight was determined at the beginning and at the end of the experimental period, and blood samples were taken for measuring electrolytes, albumin, total protein, nitrogenous substances, total and bone alkaline phosphatase, thyroid hormones, glucose, and lactate. Both diets and environments had effect on body weight gain and on the values of sodium, potassium, total calcium, magnesium, phosphorus, total and bone alkaline phosphatase, free T4, and lactate. The increase in phosphorus contents in the diet has a positive effect on body weight in the studied environments, but it unbalances blood calcium:phosphorus relations. Heat stress decreases the levels of glucose, total alkaline phosphatase, and free T4 in the blood, and increases those of lactate. Blood biochemical parameters reflect the metabolic state of the animals and can be used to evaluate nutritional balance and for early detection of metabolic alterations.

Para avaliar a influência do gene halotano sobre a curva de crescimento de suínos, bem como sua interação com o sexo do animal, foi proposta uma modelagem hierárquica Bayesiana. Nesta abordagem, os parâmetros dos modelos não-lineares de crescimento (Logístico, Gompertz e von Bertalanffy) foram estimados conjuntamente com os efeitos de sexo e genótipos do gene halotano. Foram utilizados 344 animais F2(Comercial x Piau) pesados ao nascer, aos 21, 42, 63, 77, 105 e 150 dias. O modelo Logístico foi aquele que apresentou melhor qualidade de ajuste por apresentar menor DIC (Deviance Information Criterion) que os demais. As amostras das distribuições marginais a posteriori para as diferenças entre as estimativas dos parâmetros do modelo Logístico indicaram que o peso dos machos à idade adulta com genótipo heterozigoto (HalNn) foi superior ao dos homozigotos (HalNN). A título de comparação, também foi considerada a abordagem frequentista tradicional, baseada em dois passos distintos, a qual, por apresentar um menor poder de discernimento estatístico, não mostrou diferenças significativas

A hierarchical Bayesian modeling was used to evaluate the influence of halothane gene and its interaction with sex on pig´s growth curves. Under this approach, the parameters from growth models (Logistic, Gompertz and von Bertalanffy) were estimated jointly with the effects of halothane gene and sex. A total of 344 F2 (Commercial x Piau) animals were weighted at birth, 21, 42, 63, 77, 105 and 150 days in life. The Logistic model has presented the best fit based on DIC (Deviance Information Criterion). Thus, the samples from marginal posterior distributions for the differences between the parameters estimates of Logistic model have indicated that the maturity weight of males with heterozygous genotypes (HalNn) was superior to males with homozygous genotypes (HalNN). In order to realize a comparison with the traditional methodology, the frequentist approach based on two distinct steps also was used, but there was not identified significant differences between growth curve parameter estimates from each group (combinations of halothane genotypes and sex)

O objetivo deste trabalho foi avaliar a eficiência do método de regressão via componentes independentes (ICR) na estimação de valores genéticos genômicos e dos efeitos de marcadores SNP para características de carcaça de uma população F2 de suínos (Piau x linhagem comercial). Os métodos foram avaliados por meio da concordância entre os valores genéticos preditos e os fenótipos corrigidos, observados por validação cruzada, e também foram comparados com outros métodos geralmente utilizados para os mesmos propósitos, tais como RR-BLUP, PCR e PLS. Os métodos ICR e PCR apresentam resultados similares, mas o método ICR apresenta maiores valores de acurácia.

The objective of this work was to evaluate the efficiency of the independent component regression (ICR) method for the estimation of genomic values and of SNP marker effects for carcass traits in a F2 pig population (Piau x commercial line). The methods were evaluated by the agreement between the genetic predicted values and the corrected phenotypes observed by cross-validation, and they were also compared with other methods generally used for the same purposes, such as RR-BLUP, PCR, and PLS. The ICR and PCR methods show similar results, but ICR has the highest accuracy prediction values.

O objetivo deste trabalho foi avaliar eficiência de modelos de regressão aleatória (MRA) para detectar locus de características quantitativas (QTL) para características de crescimento, em suínos. Utilizou-se uma população divergente F2 Piau x Comercial. A eficiência da metodologia proposta na detecção de QTL foi comparada à da metodologia tradicional de regressão por intervalo de mapeamento. Para tanto, utilizaram-se MRA com efeitos aleatórios poligênicos, de ambiente permanente e de QTL, tendo-se utilizado o enfoque de matriz de covariância "identical‑by‑descent" associada aos efeitos de QTL. Testou-se a significância dos efeitos de QTL mediante a razão de verossimilhanças, tendo-se considerado o modelo como completo quando houve efeito de QTL, ou nulo, quando não. A comparação entre os modelos foi feita nas posições dos marcadores (seis marcadores microssatélites) e nas intermediárias, entre os marcadores. O MRA detectou QTL significativo na posição 65 cM do cromossomo 7 e, portanto, foi mais eficiente que a metodologia tradicional, que não detectou QTL significativo em nenhum dos fenótipos avaliados. A metodologia proposta possibilitou a detecção de QTL com efeito sobre toda a trajetória de crescimento, dentro da amplitude de idade considerada (do nascimento aos 150 dias).

The objective of this work was to evaluate the efficiency of random regression models (RRM) to detect quantitative trait loci (QTL) for growth traits in pigs. An outbreed F2 Piau x Commercial population was used. The efficiency of the proposed methodology for QTL detection was compared to the traditional methodology of regression interval mapping. In order to do that, RRM with random polygenic effects of permanent environment and of QTL were used with the approach of the covariance matrix identical‑by‑descent, associated to the QTL effects. The significance of QTL effects was tested by the likelihood ratio, considering the described model as being complete when there was significant QTL effect, and null, when there was not. Comparison between models was made at the positions of the markers (six microsatellite markers) and at the intermediate positions between them. The RRM allowed the detection of a significant QTL at the position 65 cM of chromosome 7 and, therefore, it was considered more efficient than traditional method, which did not identify any significant QTL in any of the evaluated phenotypes. The proposed methodology enabled the detection of QTL affecting all growth trajectory within the considered age range (from birth to 150 days)

The objective of this study was to investigate the relationship between testicular echotexture and seminal quality, in addition to evaluate the testicular parenchyma echogenicity pattern in young Montana bulls classified as sound and unsound for breeding. Fifty-two young Montana Tropical Compound bulls from 22 to 33 months of age were used. The animals were previously evaluated by breeding soundness evaluation and thereafter divided into two groups of breeding soundness classes: 1 = 16 animals sound for breeding; 2 = 36 animals unsound for breeding by means of physical and morphological analysis of semen. All animals underwent an ultrasound examination of the testes, and the images were analyzed with the software "Image J". ANOVA was used for statistical analysis, to determine the effect of groups in relation to testicular measurements, physical and morphological semen features and ultrasound pixel analysis. There was a difference between scrotal circumference between classes, with 39.7±2.1 cm and 37.3±3.1 cm for sound and unsound animals, respectively. Regarding testicular echotexture, mean values for the pixel intensity were 95.7 and 94.0 for sound and unsound animals for breeding, respectively, with no difference between the classes. None of the studied parameters were correlated with each other, indicating that the quantification of the pixel intensity in testicular echotexture was not effective in determining the degree of sexual maturity in Montana Tropical Compound bulls.

Objetivou-se estimar parâmetros genéticos de características de carcaça, cortes de carcaça, qualidade de carne e desempenho de suínos em uma população F2 (Piau x linhagem comercial), para melhor se compreender a herança e a associação entre essas características. Para obter as estimativas de herdabilidades e correlações genéticas foi utilizado um modelo animal unicaracterístico e bicaracterístico, respectivamente, e os parâmetros foram estimados a partir dos componentes de variância e covariância, obtidos pelo método da máxima verossimilhança restrita por meio do programa MTDFREML. As herdabilidades estimadas, em modelo unicaracterístico, variaram de 0,10 a 0,43 para o grupo de características de carcaça, de 0,07 a 0,47 para cortes de carcaça, de 0,14 a 0,40 para qualidade de carne e de 0,18 a 0,86 para características de desempenho. As correlações genéticas estimadas em modelo bicaracterístico foram altas para algumas características, o que pode ser indicativo de que estas são controladas pelos mesmos genes ou genes ligados. Estudos futuros de mapeamento dos locos de características quantitativas, nesta população permitirão uma melhor compreensão das causas das correlações genéticas existentes entre as características, bem como determinar em qual região cromossômica localiza-se os locos de características quantitativas.

The aim of this work was to estimate genetic parameters for carcass, carcass cuts, meat quality and performance traits in an F2 swine population (Piau x commercial strain) in order to understand the inheritance of the traits and the association among them. Heritability estimates and genetic correlations were obtained using univariate and bivariate animal models, respectively, and (co)covariance components were obtained by means of restricted maximum likelihood analyses using the software MTDFREML. The heritability estimates using single trait model ranged from 0.10 to 0.43 for carcass, 0.07 to 0.47 for carcass cuts, 0.14 to 0.40 for meat quality and 0.18 to 0.86 for performance traits. The genetic correlation estimates using bi-trait model were high for several traits, showing that they are controlled by the same genes or linked genes. These results suggest that a better understanding of the genetic correlation among the traits, as well as, the quantitative trait loci position can be obtained by mapping studies in this population.

Objetivou-se verificar o efeito de três protocolos de criopreservação sobre a viabilidade espermática pósdescongelamento de suínos da raça Piau (Sus scrofa), por meio de testes de avaliação in vitro e in vivo. Foram coletados 22 ejaculados de 5 machos adultos da raça Piau por meio do método da mão enluvada. Para verificar a viabilidade espermática do sêmen in natura e pós-descongelamento, foram avaliados a motilidade e o vigor espermático, o teste hiposmótico, a coloração supra-vital e a porcentagem de acrossomas normais. Para o congelamento, os ejaculados foram fracionados e submetidos em: protocolo 1, método de congelamento preconizado por Fürst et al. (2005), modificado quanto aos meios diluentes; protocolo 2, método preconizado por Fürst et al. (2005), modificado quanto à curva de resfriamento; e protocolo 3, método preconizado por Ohata et al. (2001). Para testar a fertilidade in vivo do sêmen congelado/descongelado, foram realizadas 23 inseminações intrauterinas (pós-cervicais) em 14 fêmeas da raça Piau com o sêmen proveniente do protocolo 3. Os valores médios obtidos com o uso dos protocolos 1 e 2 pós-descongelamento foram inferiores aos obtidos com o protocolo 3. Quatro porcas adultas ficaram gestantes (28,6% de taxa de fertilidade). O protocolo de congelamento preconizado por Ohata et al. (2001), com período de equilíbrio de 90 minutos a 22-26 ºC, permite obter melhores resultados de viabilidade espermática in vitro em comparação aos outros dois protocolos. A ausência de período de equilíbrio do protocolo 1 e a curva de resfriamento utilizada no protocolo 2 afetam negativamente os parâmetros de viabilidade espermática avaliados no presente estudo. Apesar dos resultados satisfatórios in vitro para o congelamento de sêmen com a utilização do protocolo 3, o mesmo apresenta baixa taxa de fertilidade (28,6%).

The objective of this study was to verify the effect of three protocols of cryopreservation on the sperm viability post-thawing of swine from the Piau breed (Sus scrofa), by means of evaluation assays in vitro and in vivo. Twenty-two ejaculates of 5 adult males of the Piau breed trough the gloved-hand method. In order to verify the sperm viability of the raw semen and post-thawing, the following traits were evaluated: sperm motility and vigor, hypoosmotic test, supra-vital color test and percentage of normal acrosomes. To freezing, the ejaculates were fractioned and submitted in: method 1, method of freezing recommended by Fürst et al. (2005), modified according to media extender; method 2, recommended by Fürst et al. (2005), modified according to the cooling curve; and method 3, recommended by Ohata et al. (2001). To test the in vivo fertility of the frozen/thawed semen, 23 intra-uterine (post-cervical) inseminations were performed in 14 females of the Piau breed, with semen from method 3. The mean values obtained with the use of methods 1 and 2 and post-thawing were inferior to those obtained with method 3. Four adult sows got pregnant (28.6% fertility rate). The freezing method recommended by Ohata et al. (2001), with balance period of 90 minutes at 22-26 ºC, enables higher results of in vitro sperm viability in comparison with the two other methods. The absence of balance period of method 1 and the cooling curve utilized in protocol 2 affect negatively the parameters of sperm viability evaluated in the present study. In spite of the satisfactory results in vitro for the freezing of semen with the utilization of method 3, it presents low fertility rate (28.6%).

Aiming to determine the relationship between the frequency of testicular shape and the andrological aspects in young Nellore bulls, 18,676 animals were assessed. All andrological examinations were performed between the years 2000 and 2008. Animals were classified as able for breeding, able for breeding in natural mating system, unable for breeding and discarded. The testicular shape was classified as long, fairly long, oval-long, spherical-oval, and spherical. The analysis of Pearson correlations was performed for testicular shape with scrotal circumference, testicular volume, progressive motility, sperm vigor, major defects, minor defects and total defects. Testicles with oval shape prevailed (99.61%). It was obseved that 76.34; 66.34; 64.34; 58.33 and 50.00% of the animals were classified as sound for breeding for shapes long, fairly long, oval-long, spherical-oval, and spherical, respectively. Correlations between testicular shape with scrotal circumference, testicular volume, progressive motility, sperm vigor, major, minor and total defects were 0.26; 0.08; 0.00; 0.11; -0.02; 0.02 and -0.01, respectively. Testicular shape had no influence upon the andrological examination results. Testicles of long shape were prevalent within the population.

Objetivou-se determinar a idade à puberdade e maturidade sexual e sua relação com peso corporal e mensurações testiculares em tourinhos da raça Simental criados sob regime extensivo em clima tropical. Utilizaram-se 44 tourinhos com 1 a 30 meses de idade. As mensurações corporais e testiculares foram feitas mensalmente e os ejaculados coletados quinzenalmente, a partir dos seis meses de idade, utilizando-se o método de eletroejaculação. Observou-se idade à puberdade aos 13,42 ± 3,02 meses e maturidade sexual aos 21,43 ± 6,6 meses de idade, com peso corporal e perímetro escrotal, respectivamente, de 324,2 ± 23,7 kg e 26,90 ± 1,41 cm para a puberdade e 360 ± 69,04 kg e 34,88 ± 3,9 cm para maturidade sexual. Este estudo revelou idade tardia para a cronologia dos eventos reprodutivos, com relação direta do tipo de manejo adotado.

The objective of this study was to determine the age at puberty and sexual maturity and its relationship with body weight and testicular measurements in Simmental young bulls raised under pasture conditions in a tropical climate. Forty-four young bulls at 1 to 30 months of age were used. Body and testicular measurements were made monthly and ejaculates collected fortnightly, from six months of age by using the method of electroejaculation. Age at puberty was 13.42 ± 3.02 months and sexual maturity was observed at 21.43 ± 6.6 months of age, with body weight and scrotal circumference of 324.2 ± 23.7 kg and 26.90 ± 1.41 cm for puberty and 360 ± 69.04 kg and 34.88 ± 3.9 cm to sexual maturity, respectively. This study found late age to the timing of reproductive events, with direct relation to the type of management adopted.

Foram utilizados 72 leitões, 36 machos castrados e 36 fêmeas, com peso inicial de 14,97 ± 0,36 kg para avaliar níveis de fósforo disponível (Pd). Os animais foram distribuídos em delineamento experimental de blocos ao acaso, com seis níveis de Pd (0,107; 0,214; 0,321; 0,428; 0,535 e 0,642%), seis repetições e dois animais (um macho castrado e uma fêmea) por unidade experimental. A temperatura interna da sala foi mantida em 24,5 ± 1,2ºC e a umidade relativa do ar em 76,3 ± 8,5%. Os níveis de Pd influenciaram o consumo de ração diário e o ganho de peso diário, que aumentaram de forma quadrática até os níveis estimados de 0,420 e 0,443%, respectivamente, e a conversão alimentar, que melhorou de forma quadrática até o nível estimado de 0,461%. Verificou-se efeito dos níveis de Pd sobre a quantidade de fósforo e cinzas no osso, que aumentou de forma quadrática até os níveis estimados, respectivos, de 0,525 e 0,520%. Os níveis de Pd melhoraram a deposição diária de proteína na carcaça, que aumentou de forma quadrática até o nível estimado de 0,394%, e não afetaram a deposição diária de gordura na carcaça. Os níveis de Pd que proporcionam os melhores resultados de ganho de peso, conversão alimentar e mineralização óssea de suínos de alto potencial genético para deposição de carne magra mantidos em ambiente termoneutro na fase dos 15 aos 30 kg são respectivamente 0,443; 0,461 e 0,525%, que correspondem a consumos diários estimados de 5,25; 5,45 e 6,14 g de fósforo disponível.

It was used 72 pigs, 36 castrated males and 36 females, with initial weight of 14.97 ± 0.36 kg to evaluate levels of dietary available phosphorus (aP). The animals were distributed in a completely randomized block design, with six levels of aP (0.107; 0.214; 0.321; 0.428; 0.535 and 0.642%), six replicates and two animals (one castrated male and one female) per experimental unit. Air temperature and relative humidity in the room were kept at 24.5 ± 1.2°C and 76.3 ± 8.5%, respectively. The levels of aP influenced both daily feed intake and daily weight gain, which increased in a quadratic way up to the estimated levels of 0.420% and 0.443%, respectively and feed conversion, which improved in a quadratic manner up to the estimated level of 0.461%. It was observed the effects of levels of aP on quantity of phosphorus and ash in the bone, which increased in a quadratic manner up to the estimated levels of 0.525% and 0.520%, respectively. Levels of Ap affected daily protein deposition in the carcass, which increased in a quadratic way up to the estimated level of 0.394%. There was no effect of levels of aP on daily fat carcass deposition. Levels of aP that provided the best results for daily weight gain, feed conversion and bone mineralization in swines with high genetic potential for lean meat kept in thermoneutral environment, from 15 to 30 kg are 0.443, 0.461 and 0.525%, respectively, corresponding to estimated daily intakes of 5.25, 5.45 and 6.14 g of aP.