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This work aimed to estimate the variance components and genetic correlations for milk yield (MiY), mean flow rate (MnF), maximum flow rate (MxF), and electrical conductivity (EC) of milk, in a robotic milking system. IT was analyzed a total of 137 lactations from 110 primiparous and multiparous Holstein cows, with 42,009 observations, from 2018 to 2020 in a dairy herd in the state of Querétaro. Genetic evaluation was performed using a mixed regression animal model. To estimate heritability (h²), the restricted maximum likelihood algorithm was used to calculate the variance components, the BLUE estimator and the BLIP predictor, for each of the variables subject to the research. The estimated h² for MiY (0.62) was the highest of those calculated, and h² was also estimated for MnF (0.44), MxF (0.33), and EC (0.28); it is considered that one of the aspects that influenced the values was the variability of each daily observation. Genetic correlations for MiY were negative for MnF (-0.6117) and MxF (-0.7666); in contrast, for the trait of EC (-0.1669), the correlation was low. The estimated genetic correlations for MxF were positive for MnF (0.7422) and EC (0.5351); finally, a positive genetic correlation was estimated for MnF and EC (0.3546). The results presented allow to understand the relationships between flow rate, conductivity, and yield, and they indicate the importance of these characteristics for a genetic selection program. [ABSTRACT FROM AUTHOR]

The knowledge and modeling of lactation curves make it possible to identify factors that help explain environmental and genetic variations that allow the implementation of a selection program. This work aimed to evaluate different models for milk production, fat, and protein curves in Holstein cattle in Mexico and some factors that affect them. The information used was from 125,982 lactations belonging to 68,804 animals born from 2000 to 2020. The effect of calving number, season of the year, and herd was evaluated. R's Lactcurves package was employed to fit the 38 models included in the package, of which the best four (Wood, Wilmink, Ali & Schaeffer, and modified Pollot) were chosen and then used to model the individual curves through a nonlinear regression model. The parameters calculated for each model were statistically different among the number of lactations (P<0.05), as well as the number of calving, calving season, and herd (P<0.01). The modeled curves have similar shapes to those reported in other studies, except those obtained for protein in the third and fourth or more calvings with the modified Pollot model. The equation proposed by Wilmink was the one that presented the best fit for the study population according to the different evaluation criteria. Using the model that best suits the data will give a closer predictions to reality, and it can be applied to different areas, such as genetic improvement. [ABSTRACT FROM AUTHOR]

The objective was to evaluate some morphological characteristics of backyard chickens (n=255) coming from 65 rural production units located in 52 municipalities of 18 States of the Mexican Republic. The statistical model included sex, state, and municipality within state. Sex affected all the response variables (P<0.0001), except massiveness index (P=0.3369). State affected all the response variables (P<0.0001) and municipality was only important for wingspan (P<0.0001), body weight (P<0.0271) and stockiness index (P<0.0267). Male chickens had greater (P<0.0001) body length (4.85 cm more), wingspan (5.66 cm more), breast circumference (2.94 cm more), shank length (1.73 cm more), body weight (0.65 kg more) and massiveness index (0.99 percentage points) than female chickens. Body weight increased 126 g (P<0.01) in males and 61 g in females (P<0.01) for each centimeter increment in breast circumference. Body weight showed to be moderately correlated (P<0.01) with body length (r= 0.65), wing span (r= 0.49), length of the shank (r= 0.67) and highly correlated with breast circumference (r= 0.76 in males). The Mexican backyard chicken presented significant morphological differences between males and females for traits studied, except for massiveness index. [ABSTRACT FROM AUTHOR]

Since their introduction to Mexico goats have undergone a long process of adaptation and selection, resulting in highly rustic local animals. However, importation of improved breeds has led to the extinction of some regional breeds. For example, the Criolla Negra goat breed is known for its rusticity and high milk quality, but is in decline. A genetic characterization was done of a Criolla Negra population. Hair samples were collected in three goat herds located in different municipalities of the state of Querétaro, Mexico: Cadereyta de Montes (n= 7); El Marqués (n= 11); and San Juan del Río (n= 27). Thirty microsatellites were used to quantify the number of alleles per marker (NA), median number of alleles (MNA), number of effective alleles (NEA), observed heterozygosis (Ho), expected heterozygosis (He), polymorphic data content (PDC), the fixation index (FIS) and Hardy Weinberg equilibrium (HWE). The Criolla Negra population was compared to thirteen breeds forming part of the BioGoat project. Genetic diversity was found to be high in this population. A total of 243 alleles were identified with an MNA of 8.1 alleles per marker. The markers were informative (PDC= 0.06) for polymorphism. The He (0.71) and Ho (0.62) values indicate a slight imbalance in the population. Reynolds genetic distance results showed the Criolla Negra breed to be genetically furthest from the Anglonubia breed and nearest the Murciano-Granadina breed. The studied Criolla Negra goat population exhibits a breed structure well differentiated from the other breeds in the analysis. [ABSTRACT FROM AUTHOR]

A medida que disminuyen los costos de la genotipificación, la demanda de ésta crece entre los ganaderos. En la mayoría de los hatos pecuarios es importante controlar el aumento del coeficiente de consanguinidad. Si bien esto es un motivo considerable para llevar a cabo la genotipificación, con frecuencia los productores desconocen los demás beneficios que puede traerles. El propósito de este estudio fue demostrar que es posible utilizar los chips SNP como una herramienta eficaz para el manejo de los hatos utilizando una población de ganado italiano Holstein-Friesian. Después de filtrar, se retuvo un total de 44 animales y 27,365 SNP para analizarlos. Los análisis de componentes principales (ACP) lograron identificar al progenitor y el efecto del origen del mismo en los análisis de componentes (ACP), y a la vez determinar que los sementales no influyen en los valores individuales del índice de selección genética. Los coeficientes de consanguinidad calculados a partir de los genotipos (FIS) permitieron tener un atisbo de la heterocigosidad del hato y determinar que la variabilidad genética se está manteniendo exitosamente. Por otra parte, se dedujeron los coeficientes de consanguinidad a nivel genético con base en los tramos de homocigosidad (FROH) y se los comparó con los índices de consanguinidad basados en el pedigrí (FPED). Además, se identificaron 1,950 tramos de homocigosidad (ROH) con una longitud promedio de ROH de 4.66 Mb. Se caracterizaron los genes y QTL dentro de las regiones genéticas más comúnmente asociadas (primer 1 % y primer 5 % de los SNP). Estos resultados indican que la genotipificación de hatos pequeños, aunque a una densidad baja, facilita una mejor comprensión de la variabilidad genética dentro del hato y así, permiten a los productores gestionar su ganado desde una perspectiva genética. [ABSTRACT FROM AUTHOR]

Data from 241 interviews collected in 2013 was analyzed to characterize populations of pigs (Mexican Hairless Pig (MH), Cuino Pig (CU) and Crossbred Pig (UD)). Variables were body weight (BW), head length (HL), body length (BL), thoracic perimeter (CG), height at withers (HW), croup width (RW), number of nipples (TC), dense or sparse hair (HD), presence or absence of tusks (TU), short or long snout (ST), upright or floppy ears (ER), calm or restless temperament (TM), proportionality index (PI), body index (BI) and relative weight index (RWI). Analyses were carried out with GLM and GENMOD of SAS. Models included state and population. Population was significant (P<0.05) for BW, BL, CG, HW, RW, TU, TM, PI, BI and RWI. Coefficients of variation (VC) showed the minor and major values for BW (18.8 %) and CG (27.8 %). VC were 13.0, 14.6 and 45.8 % for PI, BI and RWI. Least squares means for MH, CU and UD were: 48.06±6.17a, 35.93±3.04b and 61.11±7.42a kg (BW); 77.81±3.65ab, 69.56±2.02a and 88.52±4.93b cm (BL); 80.55±3.98ab, 71.72±2.20a and 93.23±5.37b cm (CG); 56.88±2.45ab, 51.26±1.36a and 60.32±3.31b cm (HW); 57±4a, 71±19b and 62±34a % (HD); 68±31ab, 70±14a and 61±27b% (TU); 65±30a, 56±12b and 62±3a% (TM). The MH and UD populations were similar in morphometry and different from the CU population. The CU population showed lower weight, smaller size and calmer temperament. The characterization of these populations is important for designing strategies for their conservation and efficient use. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]