34 resultados para prediction equations
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O objetivo deste trabalho foi desenvolver equações de predição da composição química corporal de zebuínos, por intermédio da análise química de amostra de seção representativa da carcaça. Utilizaram-se sessenta e três animais não-castrados das raças Gir, Guzerá, Mocho de Tabapuã e Nelore. Os conteúdos corporais de proteína, gordura e macroelementos minerais (cálcio, fósforo, potássio, magnésio e sódio) foram determinados analisando-se amostras de seção da carcaça incluindo a 9ª, 10ª e 11ª costelas (seção HH) e dos demais tecidos corporais. Os teores de proteína, gordura, energia e macroelementos minerais da secção HH, com exceção para o magnésio, mostraram-se altamente correlacionados com a composição química corporal. As equações de predição baseadas na composição química da secção HH mostraram-se confiáveis para estudos comparativos da composição corporal de zebuínos.
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This study was carried out to determine body composition and magnesium, potassium and sodium requirements for weight gain of Santa Ines lambs (hairy coat breed). Eighteen animals were used with average 15 kg initial LW. At the beginning of the experiment, six animals were slaughtered for the determination of the amount of each mineral retained in the body, and serving as reference animals in the comparative slaughter technique. The remaining 12 animals were divided in two groups: six were ad libitum fed and six animals were restricting fed at maintenance plus 20%. The animals from the ad libitum and restrict feeding groups started in the experimental period by pairs and they both were slaughtered when the animals from the ad libitum group reached 25 kg LW. The estimates of magnesium, potassium and sodium body composition were obtained through the prediction equations obtained by the logarithm regression of the amount of each present minerals in the empty body in function of the empty body weight (EBW). The net requirements for weight gain were obtained through the derivation of these prediction equations. The estimates of body composition per kg EBW for the animals from 15 to 25 kg were: 0.591 and 0,578 g for Mg: 2.914 and 2.776 g for K 1.830 and 1.637 g for Na; and the net requirements for kg weight gain were: 0.515 and 0.503 g for Mg: 2.408 and 2.294 g for K; 1.315 and 1.177 g for Na, respectively.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The research was carried out to determine body composition and calcium and phosphorus requirements of Santa Ines lambs. Eighteen entire male lambs with average initial live weight of 15 kg were used. The animals were allotted to three groups: six animals were slaughtered at the beginning of the experiment, to access the amount of calcium and phosphorus present in the body, as reference animals for the comparative slaughter technique. Six animals were ad libitum fed and six were restrict fed (maintenance level plus 20%). The animals ad libitum and restrict fed started the experimental period by pairs and they were both slaughtered when the first reached 25 kg body weight. The body composition was estimated through the prediction equations obtained by regression of the logarithm of the amount of calcium and phosphorus in the empty body on the logarithm of the empty body weight. Net requirements for calcium and phosphorus for maintenance and the absorption coefficient were obtained through the correlation between the amount of each mineral consumed and retained in the animal body. The net requirements maintenance for live weight gain were obtained by means of derivation of the prediction of body composition equations. The net requirements maintainance of calcium and phosphorus for animals from 15 to 25 kg body weight were: 305 mg Ca/day and 325 mg P/day and net requirements for kg of the body weight gain for animals with 15 and 25 kg LW were 11.41 and 10.33 g Ca and 5.72 and 4.94 g P, respectively. The absorption coefficients were estimated to be .44 and 0.55 for Ca and P, respectively.
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This work aimed to compare intake prediction equations with values obtained by direct methods using chopped elephant-grass offered to crossbreed lactating cows with rumen canulas. The experimental design was a 3 x 3 Latin square (three animals and three cutting ages: 30, 45 and 60 days). The equations used for intake prediction (y) were: (1) y= -1.19 + 0.035(a+b) + 28.5c; (2) y= [%NDF on DM]*[NDF intake]/[(1- a - b)/KP+b/(c+kp)]/24; (3) y= -0.822 + 0.0748(a+b) + 40.7c and (4) equation 2 with values of intake measured directly. The predictions of NDF intake by equations were not different among treatments, instead of the difference among values measured directly: the 30 day-old had lower intake (5.29 kg/day) in relation to 45 (6.57 kg/day) and 60 (7.31 kg/day) day-old grasses. In general, equations overestimated the DM intake in relation to direct measuring (9.0 kg/cow/day), with exception of equation 3 which underestimated the intake (7.7 kg/day). The means of DM intake found by equations 1 and 2 (13.7 and 13.4 kg/cow/day, respectively) were similar between themselves and superior in relation to those found by equation 4 (9.7 kg/cow/day). The intakes measured directly were similar to those found in equation 4 and higher than those found by equation 3. The mean of rumen fill of 7.5 kg was superior to those of 5.2 kg estimated by equation. The prediction equations based on in situ degradability parameters do not supply estimates of DM intake, NDF intake and rumen fill in agreement with values obtained by direct methods.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Zootecnia - FMVZ
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Ciências Odontológicas - FOAR
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A data set based on 50 studies including feed intake and utilization traits was used to perform a meta-analysis to obtain pooled estimates using the variance between studies of genetic parameters for average daily gain (ADG); residual feed intake (RFI); metabolic body weight (MBW); feed conversion ratio (FCR); and daily dry matter intake (DMI) in beef cattle. The total data set included 128 heritability and 122 genetic correlation estimates published in the literature from 1961 to 2012. The meta-analysis was performed using a random effects model where the restricted maximum likelihood estimator was used to evaluate variances among clusters. Also, a meta-analysis using the method of cluster analysis was used to group the heritability estimates. Two clusters were obtained for each trait by different variables. It was observed, for all traits, that the heterogeneity of variance was significant between clusters and studies for genetic correlation estimates. The pooled estimates, adding the variance between clusters, for direct heritability estimates for ADG, DMI, RFI, MBW and FCR were 0.32 +/- 0.04, 0.39 +/- 0.03, 0.31 +/- 0.02, 0.31 +/- 0.03 and 0.26 +/- 0.03, respectively. Pooled genetic correlation estimates ranged from -0.15 to 0.67 among ADG, DMI, RFI, MBW and FCR. These pooled estimates of genetic parameters could be used to solve genetic prediction equations in populations where data is insufficient for variance component estimation. Cluster analysis is recommended as a statistical procedure to combine results from different studies to account for heterogeneity.
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Pós-graduação em Zootecnia - FCAV
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A semi-analytical approach is proposed to study the rotational motion of an artificial satellite, under the influence of torque due to the solar radiation pressure, and taking into account the influence of Earth's shadow. Using Andoyer variables the equations for the rotational motion are presented in extended Hamiltonian form. In order to get a solution for the state variables close to an actual motion, the considered model for the shadow function takes into account physical and geometric factors and three specific regions: shadow, penumbra and full light. A mapping for the shadow function is proposed and a semi-analytical process is applied. When the satellite is totally illuminated or it is inside the penumbra, a known analytical solution is used to compute the satellite's attitude. A numerical simulation shows, when the penumbra region is included, the attenuation of the rotational motion during the transition from the shadow to the illuminate region and vice versa. (c) 2005 Published by Elsevier Ltd on behalf of COSPAR.
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An analytical approach for spin-stabilized spacecraft attitude prediction is presented for the influence of the residual magnetic torques. Assuming an inclined dipole model for the Earth's magnetic field, an analytical averaging method is applied to obtain the mean residual torque every orbital period. The orbit mean anomaly is utilized to compute the average components of residual torque in the spacecraft body frame reference system. The theory is developed for time variations in the orbital elements, and non-circular orbits, giving rise to many curvature integrals. It is observed that the residual magnetic torque does not have component along the spin axis. The inclusion of this torque on the rotational motion differential equations of a spin stabilized spacecraft yields conditions to derive an analytical solution. The solution shows that residual torque does not affect the spin velocity magnitude, contributing only for the precession and the drift of the spin axis of the spacecraft. (c) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.