RESUMEN
The goal of this research, conducted in the most southern part of Taiwan, was to create a new genotype: the "Hengchun Black Goat" (HB). Nubian (NU) goats were first crossed with a local breed, the Taiwan native (TN), then the F1 females were crossed with the imported black Boer (BO) bucks. The upgraded genotypes were then compared with the parental breeds and Kinmen (KM), another local breed, for growth traits and body conformation. The study concerned 1,136 kids born between 2005 and 2007. The analysed traits were body weight (BW), average daily gain and three linear measurements, namely height at withers, body length and chest girth. The results indicated that environmental factors, sex, birth and rearing type, dam parity and birth year had significant effects from birth to 6 months of age. The same differences persisted to 1 year. At 6 months of age, the least square means of BW were 16.2, 19.2, 25.1, 32.0, 23.9, 23.8, 23.0 and 23.9 kg, for KM, TN, NU, 1/2BO, 3/4BO, 7/8BO, BO and HB, respectively. These first results also indicate that the growth performances of the newly created line, Hengchun Black, were equivalent to those of Boer goats.
Asunto(s)
Constitución Corporal/fisiología , Cruzamiento/métodos , Cabras/crecimiento & desarrollo , Cabras/genética , Análisis de Varianza , Crianza de Animales Domésticos/métodos , Animales , Constitución Corporal/genética , Pesos y Medidas Corporales , Cruzamientos Genéticos , Femenino , Modelos Lineales , Masculino , Especificidad de la Especie , TaiwánRESUMEN
BACKGROUND: The pre-weaning growth rate of lambs, an important component of meat market production, is affected by maternal and direct genetic effects. The French genetic evaluation model takes into account the number of lambs suckled by applying a multiplicative factor (1 for a lamb reared as a single, 0.7 for twin-reared lambs) to the maternal genetic effect, in addition to including the birth*rearing type combination as a fixed effect, which acts on the mean. However, little evidence has been provided to justify the use of this multiplicative model. The two main objectives of the present study were to determine, by comparing models of analysis, 1) whether pre-weaning growth is the same trait in single- and twin-reared lambs and 2) whether the multiplicative coefficient represents a good approach for taking this possible difference into account. METHODS: Data on the pre-weaning growth rate, defined as the average daily gain from birth to 45 days of age on 29,612 Romane lambs born between 1987 and 2009 at the experimental farm of La Sapinière (INRA-France) were used to compare eight models that account for the number of lambs per dam reared in various ways. Models were compared using the Akaike information criteria. RESULTS: The model that best fitted the data assumed that 1) direct (maternal) effects correspond to the same trait regardless of the number of lambs reared, 2) the permanent environmental effects and variances associated with the dam depend on the number of lambs reared and 3) the residual variance depends on the number of lambs reared. Even though this model fitted the data better than a model that included a multiplicative coefficient, little difference was found between EBV from the different models (the correlation between EBV varied from 0.979 to 0.999). CONCLUSIONS: Based on experimental data, the current genetic evaluation model can be improved to better take into account the number of lambs reared. Thus, it would be of interest to evaluate this model on field data and update the genetic evaluation model based on the results obtained.
Asunto(s)
Tamaño de la Camada , Ovinos/genética , Algoritmos , Análisis de Varianza , Animales , Femenino , Herencia , Modelos Genéticos , Modelos Estadísticos , Ovinos/crecimiento & desarrollo , DesteteRESUMEN
A 12-generation selection experiment involving a selected line (S) and a control line (C) has been conducted since 1992 with the aim of increasing the number of fertile eggs laid by the Brown Tsaiya duck after a single artificial insemination (AI) with pooled Muscovy semen. On average, 28.9% of the females and 17.05% of the males were selected. The selection responses and the predicted responses showed similar trends. The average predicted genetic responses per generation in genetic standard deviation units were 0.40 for the number of fertile eggs, 0.45 for the maximum duration of fertility, and 0.32 for the number of hatched mule ducklings' traits. The fertility rates for days 2-8 after AI were 89.14% in the S line and 61.46% in the C line. Embryo viability was not impaired by this selection. The largest increase in fertility rate per day after a single AI was observed from d5 to d11. In G12, the fertility rate in the selected line was 91% at d2, 94% at d3, 92% at days 3 and 4 then decreased to 81% at d8, 75% at d9, 58% at d10 and 42% at d11. In contrast, the fertility rate in the control line showed an abrupt decrease from d4 (74%). The same tendencies were observed for the evolution of hatchability according to the egg set rates. It was concluded that selection for the number of fertile eggs after a single AI with pooled Muscovy semen could effectively increase the duration of the fertile period in ducks and that research should now be focused on ways to improve the viability of the hybrid mule duck embryo.
Asunto(s)
Patos/fisiología , Fertilidad , Hibridación Genética , Animales , Patos/genética , Femenino , Inseminación Artificial , Masculino , Modelos GenéticosRESUMEN
A seven-generation selection experiment comprising a selected (S) and a control (C) line was conducted with the objective of increasing the number of fertile eggs (F) of the Brown Tsaiya duck after a single artificial insemination (AI) with pooled Muscovy semen. Both lines consisted of about 20 males and 60 females since parents in each generation and each female duck was tested 3 times, at 26, 29 and 32 weeks of age. The fertile eggs were measured by candling at day 7 of incubation. The selection criterion in the S line was the BLUP animal model value for F. On average, 24.7% of the females and 15% of the males were selected. The direct responses to the selection for F, and correlated responses for the number of eggs set (Ie), the number of total dead embryos (M), the maximum duration of fertility (Dm) and the number of hatched mule ducklings (H) were measured by studying the differences across the generations of selection between the phenotypic value averages in the S and C lines. The predicted genetic responses were calculated by studying the differences between the S and C lines in averaged values of five traits of the BLUP animal model. The selection responses and the predicted responses showed similar trends. There was no genetic change for Ie. After seven generations of selection, the average selection responses per generation were 0.40, 0.33, 0.42, 0.41 genetic standard deviation units for F, M, Dm, and H respectively. Embryo viability was not impaired by this selection. For days 2-8 after AI, the fertility rates (F/Ie) were 89.2% and 63.8%, the hatchability rates (H/F) were 72.5% and 70.6%, and (H/Ie) were 64.7% and 45.1% in the S and C lines respectively. It was concluded that upward selection on the number of fertile eggs after a single AI with pooled Muscovy semen may be effective in ducks to increase the duration of the fertile period and the fertility and hatchability rates with AI once a week instead of twice a week.