Características funcionais e produtivas em bovinos da caça Canchim
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Data
2017-05-09
Autores
Gomes, Fabio Jose [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A utilização de animais como reprodutores em programas de melhoramento genético de bovinos está associada ao registro genealógico pela Associação de Criadores. O objetivo neste trabalho foi avaliar e relacionar a aprovação dos animais ao registro genealógico definitivo com as características avaliadas no programa de avaliação genética da raça Canchim. Foram estimados parâmetros genéticos, por meio de modelo multicaracterística, para os pesos ao nascimento, ao desmame e ao sobreano, escores para conformação frigorífica ao desmame e ao sobreano, classificação final no registro ao desmame (CLD) e ao sobreano (CLS), escores para comprimento de umbigo e qualidade do pelo (PEL) avaliados ao desmame, e perímetro escrotal ao sobreano (PE), e por modelos bicaracterística para aprovação ao registro genealógico (AP) com cada uma das demais variáveis. A relação entre classificação final e as outras características avaliadas foi desdobrada pela análise de trilha para estimar efeitos diretos e indiretos. A probabilidade de aprovação ao registro genealógico foi estudada, as diferenças esperadas na progênie (DEP) para todas as características foram estimadas e foi elaborado o índice de qualificação genética (IQG) utilizado pelo Programa de Avaliação Genética do Canchim. Foi estimada a herdabilidade do escore de coloração da mucosa dos animais e foram obtidas as probabilidades de ocorrência de cada um dos escores de acordo com a coloração da mucosa dos pais. A probabilidade de um animal ser aprovado para registro na Associação Brasileira de Criadores de Canchim ao desmame foi de 77,48% (75,15% para os machos e 79,43% para as fêmeas), enquanto a probabilidade ao sobreano, dado que ele foi aprovado ao desmame, foi de 87,36% (86,43% para os machos e 87,83% para as fêmeas), e a probabilidade total ao sobreano foi de 69,63% (67,71% para os machos e 72,26% para as fêmeas). As correlações genéticas entre as características estudadas variavam de baixa negativa (-0,07) a alta positiva (0,70), com maior estimativa entre PE e CLS. A média das estimativas de herdabilidade de AP foi 0,28 e as correlações com as características citadas acima variaram de baixa (0,15) a muito alta (0,97), com maior estimativa para CLS. O maior efeito direto sobre a CLD foi de PEL (0,8211), indicando sua importância no registro genealógico provisório. O maior efeito direto sobre CLS foi de PE (2,7522), evidenciando sua importância na determinação do registro genealógico definitivo. A correlação entre a classificação dos animais pelo IQG e pela DEP de AP foi de 0,055. Foram observadas variações nas proporções da coloração da mucosa dos filhos em acasalamentos de animais com diferentes colorações de mucosas. Quando as duas primeiras classes fenotípicas da coloração da mucosa (bronze clara e bronze) foram consideradas como uma única classe, a estimativa de herdabilidade foi mais elevada (0,427 ± 0,022). Há variação genética para o escore de pigmentação de mucosa dos bovinos Canchim que permite o seu uso na seleção, visando à produção de animais mais adaptados aos trópicos. A avaliação genética reagrupando os escores em quatro classes que consideram a cor do pigmento e ignoram a intensidade de pigmentação das duas primeiras classes proporciona um modelo com controle genético aditivo mais forte. A pelagem é a característica mais importante na determinação da classificação final ao desmame e o perímetro escrotal a mais importante na classificação final ao sobreano.
The use of animals in beef cattle breeding programs is dependent on their approval to genealogical registry by the breeders association. The aim of this work was to evaluate and to relate the approval of the animals to the definitive genealogical record with the traits evaluated in the genetic evaluation program of the Canchim breed. Genetic parameters were estimated by means of a multi-trait model for birth, weaning and yearling (18 months of age) weights, slaughter conformation scores at weaning (CSW) and yearling (CSY), final registry classification scores at weaning (CLW) and yearling (CLY), navel and hair coat (HC) scores at weaning, and scrotal circumference at yearling (SCY), and using two-trait models for approval to registry (AR) with each of the above traits. The relationship of CLW and CLY with the other traits was studied by path analysis to estimate direct and indirect effects. Probabilities of approval to registry were studied, expected progeny differences (EPD) for all traits were estimated and a genetic qualification index (GQI) used by the Canchim Genetic Evaluation Program was obtained for each animal. Heritability was also estimated for color of the mucosa, and the probability of occurring the various color of mucosa in the offspring according to the mucosa of the parents were obtained. The probability of an animal being approved for registration by the Brazilian Canchim Breeders Association at weaning was 77.48%, 75.15% for males and 79.43% for females, while at yearling, given the approval at weaning, the probability was 87.36%, 86.43% for males and 87.83% for females. The total probability of an animal being approved for registration at yearling was 69.63%, 72.26% for females and 67.71% for males. The genetic correlations among the traits varied from low negative (-0.07) to high positive (0,70), with the highest value for SCY and CLY. The mean of the heritability estimates of AR was 0.28 and the genetic correlations with the other traits varied from low (0,15) to very high (0,97), the highest with CLY. HC showed the highest direct effect on CLW, 0.8211, suggesting its importance in determining temporary approval for registration, at weaning. SCY showed the highest direct effect on CLY, 2.7522, indicating its importance in determining final and definitive approval for registration, at yearling. The correlation between the classification of the animals by GQI and the EPD for AR was 0.055. There were variations in the proportion of color of mucosa of the offspring produced by mating animals with different colors of mucosa. When the first two phenotypic classes of color of mucosa (light bronze and bronze) were joined in one class, the heritability of the trait was the highest (0.427 ± 0.022). The tonality of the mucosa showed a great impact on the estimation of the genetic components. There is enough genetic variation on the mucosa pigmentation scores of the Canchim cattle that allows its use in selection to obtain animals more adapted to the tropics. The classification of mucosa into four classes considering only color of pigment and not the intensity of pigmentation of the two first classes will provide a model with better additive genetic control. Hair coat is the most important trait that establishes CLW and scrotal circumference is the most important for CLY.
The use of animals in beef cattle breeding programs is dependent on their approval to genealogical registry by the breeders association. The aim of this work was to evaluate and to relate the approval of the animals to the definitive genealogical record with the traits evaluated in the genetic evaluation program of the Canchim breed. Genetic parameters were estimated by means of a multi-trait model for birth, weaning and yearling (18 months of age) weights, slaughter conformation scores at weaning (CSW) and yearling (CSY), final registry classification scores at weaning (CLW) and yearling (CLY), navel and hair coat (HC) scores at weaning, and scrotal circumference at yearling (SCY), and using two-trait models for approval to registry (AR) with each of the above traits. The relationship of CLW and CLY with the other traits was studied by path analysis to estimate direct and indirect effects. Probabilities of approval to registry were studied, expected progeny differences (EPD) for all traits were estimated and a genetic qualification index (GQI) used by the Canchim Genetic Evaluation Program was obtained for each animal. Heritability was also estimated for color of the mucosa, and the probability of occurring the various color of mucosa in the offspring according to the mucosa of the parents were obtained. The probability of an animal being approved for registration by the Brazilian Canchim Breeders Association at weaning was 77.48%, 75.15% for males and 79.43% for females, while at yearling, given the approval at weaning, the probability was 87.36%, 86.43% for males and 87.83% for females. The total probability of an animal being approved for registration at yearling was 69.63%, 72.26% for females and 67.71% for males. The genetic correlations among the traits varied from low negative (-0.07) to high positive (0,70), with the highest value for SCY and CLY. The mean of the heritability estimates of AR was 0.28 and the genetic correlations with the other traits varied from low (0,15) to very high (0,97), the highest with CLY. HC showed the highest direct effect on CLW, 0.8211, suggesting its importance in determining temporary approval for registration, at weaning. SCY showed the highest direct effect on CLY, 2.7522, indicating its importance in determining final and definitive approval for registration, at yearling. The correlation between the classification of the animals by GQI and the EPD for AR was 0.055. There were variations in the proportion of color of mucosa of the offspring produced by mating animals with different colors of mucosa. When the first two phenotypic classes of color of mucosa (light bronze and bronze) were joined in one class, the heritability of the trait was the highest (0.427 ± 0.022). The tonality of the mucosa showed a great impact on the estimation of the genetic components. There is enough genetic variation on the mucosa pigmentation scores of the Canchim cattle that allows its use in selection to obtain animals more adapted to the tropics. The classification of mucosa into four classes considering only color of pigment and not the intensity of pigmentation of the two first classes will provide a model with better additive genetic control. Hair coat is the most important trait that establishes CLW and scrotal circumference is the most important for CLY.
Descrição
Palavras-chave
Aprovação ao registro, Características morfológicas, Cor da mucosa, Inferência bayesiana, Parâmetros genéticos, Bayesian inference, Color of mucosa, Genealogical record approval, Genetic parameters, Morphological traits