Os objetivos neste estudo foram analisar modelos não-lineares para descrever o crescimento em ovinos da raça Morada Nova criados no estado da Bahia e, após a definição do modelo de melhor ajuste, calcular a taxa de crescimento absoluto e avaliar a influência de fatores ambientais (sexo e tipo de parto) sobre os parâmetros da curva. Utilizaram-se dados de pesagem de 40 ovinos, do nascimento aos 385 dias de idade. Os modelos não-lineares utilizados foram: Brody, Von Bertalanffy, Richards, Logístico e Gompertz. Os modelos Von Bertalanffy, Brody e Richards foram os que apresentaram os melhores ajustes e são equivalentes para explicar o crescimento dos animais. A taxa de crescimento absoluto teve acentuado decréscimo na fase pós-desmama, o que indica a necessidade de se adotar um regime alimentar adequado para acompanhar as exigências de nutrientes dos animais nessa fase. Os efeitos ambientais (sexo e tipo de parto) influenciaram significativamente a taxa a maturidade (k), mas apenas o sexo do animal afetou o peso à maturidade (A). Os animais que nasceram de parto simples tiveram peso maior que o daqueles de parto duplo, e estes apresentaram ganho compensatório. Os machos tiveram maior crescimento que as fêmeas, que, por sua vez, apresentaram maior precocidade. A correlação estimada entre os parâmetros A e k foi negativa (-0,65) para o modelo Von Bertalanffy e (-0,71) para os modelos Brody e Richards, e isso indica que os animais mais precoces possuem menor probabilidade de atingir pesos elevados à idade adulta.
Resumo -O objetivo deste estudo foi analisar modelos não-lineares para descrever o crescimento em animais da raça Indubrasil no Estado do Sergipe. Após a definição do modelo de melhor ajuste, calculou-se a taxa de crescimento absoluto e avaliou-se a influência de fatores ambientais (sexo, fazenda, mês e ano de nascimento) sobre os parâmetros da curva. Utilizaram-se dados de, no mínimo, 8 pesagens, obtidas a intervalos de aproximadamente 90 dias, do nascimento aos 2 anos de idade de 1.201 bovinos, provenientes da Associação Brasileira dos Criadores de Zebu (ABCZ). Os modelos não-lineares utilizados foram: Brody, Von Bertalanffy, Richards, Logístico e Gompertz. O modelo Logístico apresentou melhor ajuste seguido dos modelos Gompertz e Von Bertalanffy. O peso assintótico (A) e a taxa de maturidade (k) estimada pelo modelo Logístico foram 427,87 kg e 0,0052, respectivamente. Constatou-se acentuado decréscimo da taxa de crescimento absoluto na fase pós-desmama, devendo ser adotado um regime alimentar adequado para acompanhar as exigências de nutrientes dos animais nessa fase. Os efeitos de ambiente influenciaram significativamente (P < 0,05) os parâmetros A e k. A correlação estimada entre os parâmetros A e k foi negativa (-0,62), indicando que os animais mais precoces possuem menor probabilidade de atingir pesos elevados à idade adulta. Palavras-chave -Bovino-crescimento. Bovino de corte-melhoramento genético.Abstract -The objective of this study was to analyze nonlinear models to describe growth of Indubrazil cattle raised in Sergipe State. After defining the best adjusted model, it was evaluated the influence of environmental effects (sex, farm, month and year of birth) over mature weight (A) and maturation rate (k). Data from 1,201 animals weighed in nearly 90-day intervals from birth up to two years of age were used, based on records from the Brazilian Association of Zebu Breeders (ABCZ). The models utilized were Brody, Von Bertalanffy, Richards, Logistic and Gompertz. The Logistic model presented best adjustment followed by Gompertz and Von Bertalanffy models. The parameters A (weight at maturity) and k (maturation rate), obtained by the Logistic model were 427.87 and 0.0052, respectively. An accentuated decrease in the absolute growth rate was observed after weaning and nutritional strategies should be performed to avoid the low weight gain at this stage. Environmental factors affected significantly the parameters A and k. The correlation estimated between the parameter A and k was negative (-0.62), indicating that fast-growing young animals are less likely to reach higher weights when adults.
-The objective of this study was to evaluate the history of the Tabapuã breed in Northeastern Brazil by determining its population structure and genetic progress. Pedigree information from animals born in the period between 1965 and 2006 and weight-adjusted data at 205 (W205), 365 (W365) and 550 (W550) days of age for bovines born between 1975 and 2006 were used. The (co)variance components and genetic value were estimated using the application MTDFREML. Also, the software ENDOG was used for pedigree analysis and parameter estimation based on the probabilities of gene origin, inbreeding and average generation interval. The heritability coefficients for direct genetic effects were 0.21±0.03, 0.26±0.04 and 0.36±0.05 for W205, W365 and W550, respectively. During the first 20 years studied, the observed effective size was small. The generation intervals by gametic pathway were: 7.7±3.4 (sire-son), 7.8±3.7 (sire-daughter), 6.9±3.3 (dam-son), 6.8 ± 3.1 (dam-daughter), and mean interval of 7.3±3.4 years. The studied population showed moderate heritability coefficients, whereas the genetic gains based on the studied traits may be higher than those estimated by genetic tendencies. Reduced generation interval, increased effective size and continuous mating control of relatives are important strategies for the genetic progress of the Tabapuã breed in the region.
We evaluated the effect of inclusion of fine mesquite pod meal (FPM) in the diet on performance, preference and palatability of diets in feedlot lambs. Five diets were formulated with increasing levels of FPM (0, 1.5, 3.0, 4.5 and 6.0%). For performance evaluation, the design was completely randomized with five treatments and seven replications. For palatability and preference analysis, the same design was used, but the treatments consisted of diets with 0 and 3% FPM and fourteen replications. The palatability was assessed considering the amount of feed consumed within 30 min., and the preference, considering the feed intake after 24 hours. FPM had no influence on weight gain, but caused a reduction in intake and an increase in dry matter digestibility for inclusion level above 2.4%. The greatest contribution of FPM inclusion is due to the increase in neutral detergent fiber digestibility. The preference and palatability in feedlot lambs is not affected by the inclusion of 3% FPM.
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