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Veracruz, Mexico

Vega-Murillo V.E.,Research Center Regional Golfo Centro | Rios-Utrera A.,Campo Experimental la Posta | Montano-Bermudez M.,CENID Fisiologia y Mejoramiento Animal | Martinez-Velazquez G.,Sitio Experimental El Verdineno
Tropical and Subtropical Agroecosystems | Year: 2012

Covariance components and genetic parameters were estimated in Simmental, Simbrah and Simmental x Zebu calves fitting six alternative models to birth weight (BW; n=105,297), 205-day weight (WW; n=82,752) and 365-day weight data (YW; n=49,450) provided by Asociación Mexicana de Criadores de Ganado Simmental Simbrah, A.C. Models ranged from a model which included direct additive genetic effects (Model 1) to a model which included direct and maternal additive genetic effects, their covariance and maternal permanent environmental effects (Model 6). Fixed effects were: contemporary group, age of dam, proportion of Simmental genes, heterozygosity and recombination losses. Estimates of direct and maternal heritability varied between alternative models. Due to the problems associated with the estimation of the direct-maternal correlation, which was extremely high (absolute value), Model 4, which included both dams' genetic and permanent environmental effects in addition to direct additive genetic effects, was considered to be the most appropriate for all traits. Application of any of the other models would result in inaccurate expected progeny differences, affecting selection efficiency. Model-4 estimates of direct heritability, maternal heritability and of the ratio of maternal permanent environmental variance to the total phenotypic variance were: 0.17, 0.01 and 0.03; 0.14, 0.02 and 0.04; and 0.15, 0.01 and 0.01 for BW, WW and YW, respectively. Source

Rios-Utrera A.,Campo Experimental la Posta | Vega-Murillo V.E.,Campo Experimental la Posta | Martinez-Velazquez G.,Sitio Experimental El Verdineno | Montano-Bermudez M.,CENID Fisiologia y Mejoramiento Animal
Tropical and Subtropical Agroecosystems | Year: 2011

Six models to estimate genetic parameters for birth weight (BW), weaning weight adjusted to 205 days (W205), and yearling weight adjusted to 365 days (W365) were compared. Model A included direct genetic effects. Model AP allowed for direct genetic and permanent environmental effect of the dam. Model AM included direct genetic and maternal genetic effects. Models AMC and AMP were the same as Model AM but they also allowed for the covariance between direct and maternal genetic effects, and the common environmental effect due to the dam, respectively; and Model AMCP was fitted for all three random effects plus the covariance between direct and maternal effects. Models were compared using the likelihood ratio text. The AMC model was selected to be the most appropriate for BW and W205, whereas Model A was chosen for W365. When maternal effects were included, direct genetic variance and direct heritability estimates were reduced for BW and W205. Direct heritability estimates with appropriate models were: 0.13, 0.21 and 0.20 for BW, W205 and W365. Heritability of maternal effects with appropriate models was: 0.15 and 0.32 for BW and W205, and direct-maternal genetic correlations with appropriate models were: -0.67 and -0.69 for BW and W205, respectively. Source

Utrera A.R.,Campo Experimental la Posta | Ponce S.I.R.,National Research Center Disciplinaria en Fisiologia y Mejoramiento Animal | Izquierdo A.V.,National Research Center Disciplinaria en Fisiologia y Mejoramiento Animal | Torres E.C.,Campo Experimental Chetumal | And 9 more authors.
Revista Mexicana De Ciencias Pecuarias | Year: 2016

The objective was to evaluate some morphological characteristics of backyard Turkeys (n=248) coming from 126 rural production units located in 75 municipalities of 24 States of the Mexican Republic. The statistical model included sex, state, and municipality within state. The three explanatory variables affected all the response variables (P<0.01), except municipality, which did not affect breast circumference (P>0.05). Male Turkeys had greater (P<0.001) body length (10.7 cm more), wingspan (11.4 cm more), breast circumference (13.8 cm more), shank length (2.5 cm more), body weight (2.5 kg more), stockiness (9.0 percentage units more) and massiveness (2.8 percentage units more) than female Turkeys. Body weight showed to be highly correlated phenotypically (P<0.01) with breast circumference in both males (r=0.74) and females (r=0.71). Body length was lowly correlated with shank length (r=0.25; P<0.01) in males, but it was not correlated with shank length in females (r=0.05; P>0.05). Body weight increased 143 g in males (P<0.01) and 113 g in females (P<0.01) for each centimeter increment in breast circumference. The predominant colors in the plumage, skin and tarsus were black, white and brown, respectively. The Mexican backyard Turkey presented significant sexual dimorphism and strong phenotypic correlation between breast circumference and body weight. Source

Pech C.I.V.M.,Campo Experimental Mococha | Vazquez J.A.T.,CENID Fisiologia y Mejoramiento Animal | Zepeda A.B.,Sitio Experimental El Verdineno | Utrera A.R.,Campo Experimental la Posta | And 4 more authors.
Revista Mexicana De Ciencias Pecuarias | Year: 2012

Genetic parameters for growth traits of Katahdin lambs were estimated using six variants of the animal model. Data on birth weight (BW; n= 13,099), weaning weight adjusted to 75 d (WW; n=11,509) and postweaning weight adjusted to 120 d (AW; n=6,886) were collected for seven years (2004-2010) in 20 states across Mexico. Analyses were carried out by ignoring or including maternal effects. The simplest model included the direct additive genetic effect as the only random effect. The most complete model included direct and maternal genetic effects, their covariance, and the maternal permanent environmental effect. Selection of the best model was based on likelihood-ratio test. When maternal effects were not taken into account, estimates of direct heritability and direct genetic variance were overestimated for all traits. Direct heritability estimates for the best model were 0.18 ± 0.03, 0.30 ± 0.04, and 0.20 ± 0.05 for BW, WW and AW, respectively. Maternal heritability estimates also varied depending on the model; estimates ranged from 0.05 to 0.23, 0.00 to 0.12, and 0.09 to 0.25 for BW, WW and AW. Ignoring maternal effects in the model would result in inaccurate genetic evaluation for growth traits in Katahdin sheep. Source

Hernandez A.C.,Colegio de Mexico | Garay A.H.,Colegio de Mexico | Quiroz J.F.E.,Campo Experimental la Posta | Vazquez A.G.,Juarez Autonomous University of Tabasco | And 2 more authors.
Revista Mexicana De Ciencias Pecuarias | Year: 2011

Three grazing frequencies (14, 21 and 28 d) and two grazing intensities (9-11 and 13-15 cm cutting height) were assessed in Mulato grass (Brachiaria hybrid 36061) in a completely randomized block design with a 3*2 factorial arrangement and three replicates. The following attributes were taken into account, herbage yield, growth rate (GR), botanic composition and leaf:stem ratio. No significant interaction (P>0.05) was found between frequency*intensity for herbage yield. Herbage yield distribution was 55, 28 and 17 % respectively for the rainy, north and dry seasons in 2007-2008, evaluation period. The highest annual herbage yield (12,310 kg DM ha-1) was recorded with 28 d grazing interval at 13-15 cm of grazing intensity. Herbage yield increased progressively when grazing frequency lengthened from 14 to 28 d (P<0.05). A similar herbage yield pattern was observed in 2008-2009. The greater growth rate (GR) was obtained in the rainy season, 36, 44 and 47 kg DM ha-1 d-1 at 14, 21 and 28 d grazing frequency, respectively. The lowest GR was found in the dry season. Relative to morphological components, the greater leaf mass yield was found in the rainy season, followed by the north and dry seasons at 28 d grazing frequency and 13-15 cm grazing height. As a conclusion, the greater herbage yield, growth rate, leaf mass and leaf:stem ratio were found in the rainy season at 13-15 cm grazing height and 28 d grazing frequency. Source

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