Conservação e melhoramento dos recursos genéticos animais da Amazônia Brasileira.

Muitas espécies animais da Amazônia estão ameaçadas de extinção ou sofrem forte pressão de descaracterização. Isto ocorre com eqüinos como o cavalo Marajoara e Puruca (Equus caballus), búfalos como o Tipo Baía e a raça Carabao do Brasil (Bubalus bubalis) e com espécies nativas, como o Muçuã (Kinosternon scorpioides). A Amazônia é uma das áreas mais predadas do planeta e a devastação que vem ocorrendo, ainda hoje, contribuí para o empobrecimento da biodiversidade, além de interferir na adaptabilidade, desempenho e sobrevivência das espécies introduzidas. No permeio de espécies amazônicas importantes como o peixe-boi, o pirarucu, os jacarés, araras diversas ou de um inseto, que nem foi catalogado pelo homem, há animais de interesse zootécnico que podem desaparecer. Os eqüinos e os búfalos fazem parte dos recursos zoogenéticos do Brasil, na Rede Nacional de Recursos Genéticos - RENARGEN, coordenada pela Embrapa CENARGEN, juntamente com inúmeras raças naturafízadas que compõem o universo da pecuária brasileira, que é a mais diversificada de fado O planeta. Nesse contexto há peculiaridades genéticas importantes, como: o único mini cavalo do Brasil, o Puruca, com características tão próprias e importantes que o fazem enfrentar as adversidade climáticas e geográficas da maior ilha flúvio-marinha do mundo, o Marajó, que abriga em contexto semelhante um dos cavalos brasileiros mais importantes, o Marajoara, não só pela rusticidade, inteligência no adestramento, força e resistência natural, como pela importâncía genética, pois deve ter grande participação na origem de outros importantes grupamentos de eqüinos da região, ou seja: os cavalos Baixadeiro (Baixada maranhense) e o Lavradeiro (dos campos de Roraima), além do Varzeiro, que domina grande parte das áreas de várzeas de Itacoatiara (Amazonas) até Prainha (Pará); dentre os búfalos há um tipo que não é reconhecido como raça, o Baio, e outro que, apesar de constituir uma raça, ainda hoje presente em todo o Sudeste asiático (o Swamp buftalo), adquiriu características próprias das condições brasileiras. Ambos fazem parte do conjunto de raças naturalizadas em conservação no nosso País. Vale ressaltar que não há, em todo o Brasil, 300 animais Baios ou 500 Carabaos, enquadrando-se na classificação da FAO, como grupos em alto risco de extinção. Existe, ainda, uma tartaruguinha característica das áreas de campo, importante para a gastronomia regional que, se conhecida, pode adquirir também grande importância como animal ornamental. Estas foram as principais razões para a criação e implantação, pela Embrapa Amazônia Oriental, do Banco de Germoplasma Animal da Amazônia Oriental - BAGAM, em 1997, destinado à conservação "on ierm" de espécies animais da Amazônia de valor socioeconômico e biológico, que apresentam risco de extinção e/ou descerectetizeçêo. Com tais ações espera-se manter as populações ameaçadas num patamar seguro de conservação, municiando a comunidade científica e a classe produtora com informações sobre os genes mais produtivos, além de assegurar a manutenção da variabilidade genética, bem como estudar a biologia das espécies, possibilitando novos estudos e descobertas.ZOOTEC

Results of two multi-chord stellar occultations by dwarf planet (1) Ceres

We report the results of two multi-chord stellar occultations by the dwarf planet (1) Ceres that were observed from Brazil on 2010 August 17, and from the USA on 2013 October 25. Four positive detections were obtained for the 2010 occultation, and nine for the 2013 occultation. Elliptical models were adjusted to the observed chords to obtain Ceres' size and shape. Two limb fitting solutions were studied for each event. The first one is a nominal solution with an indeterminate polar aspect angle. The second one was constrained by the pole coordinates as given by Drummond et al. Assuming a Maclaurin spheroid, we determine an equatorial diameter of 972 $\pm$ 6 km and an apparent oblateness of 0.08 $\pm$ 0.03 as our best solution. These results are compared to all available size and shape determinations for Ceres made so far, and shall be confirmed by the NASA's Dawn space mission.Comment: 9 pages, 6 figures. Accepted for publication in MNRA

Growth curve mixed nonlinear models in quails.

Our aim was to evaluate the use and application of different nonlinear mixed models, as well as to compare them with approach in nonlinear fixed models, for describing the growth curve of meat-type quails according to gender. A total of 15,002 and 15,408 records of males and females were used, respectively. The body weights were regressed on age of the animals using nonlinear models (Brody; Gompertz; Logistic, Morgan-Mercer-Flodin, Richards and Von Bertalanffy). All model parameters were considered fixed, whereas parameters related to asymptotic weight and maturity rate were fitted as random effects. The Bayesian Information Criterion was used to find the model of best fit. For both genders, the model that used the Morgan-Mercer-Flodin function with the inclusion of asymptotic weight as a random effect was considered the best-fitting model because it reduced the residual variance and increased the accuracy. Based on the lower absolute growth rate and growth velocity of male quails compared to that of females, it can be inferred that males should be slaughtered later. Given the results of this study, it can contribute to the current knowledge about animal yield, specifically at the best moment to slaughter and, this sense, improv the quality genetic of the populations in time

Mixed models in nonlinear regression for description of the growth of Nelore Cattle.

Body weight records were used to characterize the growth curve of Nelore cattle. Body weight was regressed as a function of age, for both sexes, by using nonlinear models through the functions of Brody, Gompertz, Logistic, Richards, Meloun 1, Von Bertalanffy, and Von Bertalanffy. The quality of the model arrangements was evaluated by employing Akaike and Bayesian Schwarz information criteria. The Brody function provided the best adaptations by the evaluators and, considering the asymptotic weight and the maturation rate as random, a reduction in residual variance of 79% for males and 83% for females was obtained in relation to the models under fixed contexts. In males, the absolute and relative growth rates ranged from 0.921 to 0.261 kg/day and 2.39 to 0.08%, respectively. For the same rates, under another approach, females ranged from 0.922 to 0.198 kg/day and 2.55 to 0.06%, respectively. Males showed greater growth acceleration at the beginning of the growth trajectory, being equal to females at 397 days of age and from that age onward they presented lower estimates. The nonlinear regression model approach under the mixed-models context allows reduction of residual variance, increasing model accuracy

The structure of Chariklo's rings from stellar occultations

Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned observations of several occultations by Chariklo's system in order to better characterize the physical properties of the ring and main body. Here, we use 12 successful occulations by Chariklo observed between 2014 and 2016. They provide ring profiles (physical width, opacity, edge structure) and constraints on the radii and pole position. Our new observations are currently consistent with the circular ring solution and pole position, to within the $\pm 3.3$ km formal uncertainty for the ring radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal significant width variations from $\sim 5$ to 7.5 km. The width of the fainter ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and outer edges of C1R are consistent with infinitely sharp boundaries, with typical upper limits of one kilometer for the transition zone between the ring and empty space. No constraint on the sharpness of C2R's edges is available. A 1$\sigma$ upper limit of $\sim 20$ m is derived for the equivalent width of narrow (physical width <4 km) rings up to distances of 12,000 km, counted in the ring plane

Constraints on (2060) Chiron's size, shape, and surrounding material from the November 2018 and September 2019 stellar occultations

After the discovery of rings around the largest known Centaur object, (10199) Chariklo, we carried out observation campaigns of stellar occultations produced by the second-largest known Centaur object, (2060) Chiron, to better characterize its physical properties and presence of material on its surroundings. We predicted and successfully observed two stellar occultations by Chiron. These observations were used to constrain its size and shape by fitting elliptical limbs with equivalent surface radii in agreement with radiometric measurements. Constraints on the (2060) Chiron shape are reported for the first time. Assuming an equivalent radius of R$_{equiv}$ = 105$^{+6}_{-7}$ km, we obtained a semi-major axis of a = 126 $\pm$ 22 km. Considering Chiron's true rotational light curve amplitude and assuming it has a Jacobi equilibrium shape, we were able to derive a 3D shape with a semi-axis of a = 126 $\pm$ 22 km, b = 109 $\pm$ 19 km, and c = 68 $\pm$ 13 km, implying in a volume-equivalent radius of R$_{vol}$ = 98 $\pm$ 17 km, implying a density of 1119 $\pm$ 4 kg m$^{-3}$. We determined the physical properties of the 2011 secondary events around Chiron, which may then be directly compared with those of Chariklo rings, as the same method was used. Data obtained from SAAO in 2018 do not show unambiguous evidence of the proposed rings, mainly due to the large sampling time. Meanwhile, we discarded the possible presence of a permanent ring similar to (10199) Chariklo's C1R in optical depth and extension. Using the first multi-chord stellar occultation by (2060) Chiron and considering it to have a Jacobi equilibrium shape, we derived its 3D shape. New observations of a stellar occultation by (2060) Chiron are needed to further investigate the material's properties around Chiron, such as the occultation predicted for September 10, 2023