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The objective was to know the population structure of Holstein animals in the family dairy system, to identify possible origins of the genetic material, to know the degree of inbreeding and to identify possible traces of selection in the genome, which allow glimpses of the traits that have been improved over the years. The study included 270 animals genotyped with the GGP-50K® chip. After genotype quality control, 43,548 autosomal SNPs were included. To know the population structure, analyses of mixtures and principal components (PCs) were performed. To know genomic inbreeding and detect traces of selection, information on runs of homozygosity (ROH) was used. Mixture analysis was performed with the Admixture software, and PC, ROH and inbreeding analyses were performed with SVS-v7.6.8. Mixture analysis showed evidence of six components, all linked to Holstein bulls families with different country of origin. The PCs did not show stratification of the population by herd. The mean inbreeding coefficient was 0.59 ± 0.53 %. In the regions of the genome with ROHs most frequent in the population (≥20 animals), numerous associations, QTLs and genes related to milk production and composition, fertility parameters, susceptibility to diseases, body conformation, feed efficiency and some characteristics of carcass composition have been reported. The results reflect the existence of a wide genetic diversity in this population and the possibility of carrying out genetic improvement work through selection without affecting inbreeding levels. [ABSTRACT FROM AUTHOR]

Records of milk production adjusted to 305 d, adult equivalent of the first lactation and two milking were used. Those come from the National Breeding in Mexico PNMG (n= 163.885), which includes records of the Holstein Association of Mexico (AHM) (n= 43.668) and National Bank of Dairy Information (BNIL) (n= 120.217). Best Linear Unbiased Predictor method was used to predict breeding values (VG) of animals. ASREML software was used with an animal model that included herd-year group-season as fixed effect and animal and residue as random effects. Averages of VG per sire were estimated weighted by the number of daughters and unweighted for PNMG, AHM and BNIL. Also, we estimated the weighted average of the sires VG of the PNMG according to their country of origin (USA, Canada, Other, Mexico). We also estimated the average of VG and phenotypic values (VF) for dairy cows. The average of VF and VG for cows PNMG, AHM and BNIL increased between 2007 and 2011. Breeders of the AHM chose sires with greater VG than the BNIL. However, breeders of BNIL used sires with high VG used more frequently. The VG for foreign sires were higher than national sires and were more commonly used by farmers. [ABSTRACT FROM AUTHOR]

Variance components and genetic parameters were estimated for total milk production at first lactation (MP1), milk yield adjusted to 305 d and adult equivalent at the first lactation (MP1std), total milk production of the first five lactations (MP5) and milk yield adjusted to 305 d and mature equivalent of the first five lactations (MP5std). The databases of the Mexican Holstein Association (MHA, n= 43,668) and of the National Bank of Dairy Information (NBDI, n= 120,217) were used. Variances were estimated by REML, using a simple animal model for MP1 and MP1std and a repeatability animal model for MP5 and MP5std. Heritability estimates ranged from low to moderate for the first lactation (0.17 ± 0.009 to 0.49 ± 0.019) and for the first five lactations (0.16 ± 0.006 to 0.41 ± 0.004). The repeatabilities for MP5 and MP5std ranged from 0.32 ± 0.002 to 0.41 ± 0.004. The inclusion of information of the NBDI on the national evaluations made possible the incorporation of production data that had not been taken into consideration before. This inclusion not only improved the accuracy of sire breeding values for milk production, but also allowed the prediction of breeding values of more foreign and domestic animals with progeny in Mexico. [ABSTRACT FROM AUTHOR]

Crossbreeding effects were evaluated in three dual purpose bovine sub-populations in the tropics, and 5,040 lactations, 4,429 birth weights and adjusted weights at 205 [3,878], 365 [3,017] and 540 [2,276] days (PN, P205, P365 y P540, respectively) from Zebu cattle (CE) and its crosses with Holstein (HS), Brown Swiss (SP) and Simmental (SM). Additive direct breed effects (PG), heterozygosity (HT) and recombination loss (RC) were estimated by a regression analysis within breed group with mixed models. Evaluated fixed effects were herd and year of freshening, season, lactation number and offspring gender for milk yield (PL) and herd, birth year and season for growth traits. Random effects for PL were direct (animal) and permanent environment and for growth traits were genetic direct and maternal and permanent maternal environmental effects. PG/HS, PG/SP y HT/SM had effects (P<0.10) on PL while PG/SP, PG/SM, HT/SM and RC/HS on PN. PG/HS y PG/SP presented effects (P<0.10) on P205, P365 and P540 while PG/SM only on P205. HT and RC had effects (P<0.10) on P205, P365 y P540 for all crosses. Results hereby presented will allow the formulation of strategies for the use of additive and non-additive genetic effects of the crossbred populations present in the Mexican humid tropical regions. [ABSTRACT FROM AUTHOR]

The effect of fibrolytic enzyme (FE) supplements and alfalfa quality (i.e. fiber content) on calf productive performance, apparent feed digestibility, and rumen development during the pre- and post-weaning period was evaluated. Before weaning, calves were fed daily 4 L of milk (MI) and solid feed (starter concentrate (SC) + alfalfa hay) ad libitum. Thirty-six, Holstein calves (3 to 7 d of age) were distributed in a random block design with six treatments: 1) MI-SC + low-fiber alfalfa; 2) treatment 1 + FE; 3) MISC + medium-fiber alfalfa; 4) treatment 3 + FE; 5) MI-SC + high-fiber alfalfa; and 6) treatment 5 + FE. Experimental period was 105 d and animals were weaned at d 60. The FE supplement improved (P<0.05) daily weight gain (DWG) (610 g vs 404 g/d) and feed efficiency (FEF) (0.55 vs 0.41) in the preweaning stage. Final dry matter intake (DMI) tended (P<0.05) to be higher (1.99 vs 1.65 kg d-1) in the animals that consumed FE-supplemented feed. Alfalfa fiber content did not affect DWG, DMI or final FEF (P>0.05). Apparent feed digestibility was similar among treatments (P>0.05) for dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF). There were significant differences (P<0.05) between the preweaning and postweaning periods in the digestibility coefficients for DM (81.5 vs 70.8 %), CP (72.5 vs 62.3 %) and NDF (81.9 vs 45.3 %). Ruminal volatile fatty acid concentration, rumen papillae size, and rumen, abomasum, and intestine digesta viscosity exhibited no significant differences (P>0.05) among treatments. Inclusion of FE improved daily weight gain and feed efficiency in the preweaning period. [ABSTRACT FROM AUTHOR]

La adición de enzimas fibrolíticas (EF) y alfalfa de diferente calidad se evaluó en 36 becerros Holstein de siete días de edad, en los periodos pre y posdestete, sobre comportamiento productivo, digestibilidad aparente y evolución ruminal. Antes del destete, los animales fueron alimentados con 4 L de leche (LE), alimento iniciador (IN) y heno de alfalfa. Los tratamientos fueron: 1) LE-IN + alfalfa baja en fibra; 2) como 1 + EF; 3) LE-IN + alfalfa regular en fibra; 4) como 3 + EF; 5) LE-IN + alfalfa alta en fibra y 6) como 5 + EF. El experimento duró 105 días, con el destete el día 60. Las enzimas mejoraron (P<0.05) ganancia de peso (GP) (610 vs 404 g/día) y eficiencia alimenticia (EA) (0.55 vs 0.41) antes del destete. El consumo de alimento (CA) tendió (P=0.06) a ser mayor (1.99 vs 1.65 kg al día) con EF. El contenido de fibra de la alfalfa no afectó GP, CA y EA (P>0.05). La digestibilidad de materia seca (MS), proteína cruda (PC) y fibra detergente neutro (FDN) no cambió por la calidad de la alfalfa ni por EF (P>0.05) en ambos periodos; se observaron diferencias entre periodos (P<0.05); la digestibilidad de MS, PC y FDN fue: 81.5 y 72.5, 81.9 y 70.8, 62.3 y 45.3 % para los periodos predestete y posdestete, respectivamente. La concentración de ácidos grasos volátiles, tamaño de papilas ruminales y viscosidad del contenido digestivo no fueron afectados (P>0.05). Las enzimas mejoraron la ganancia de peso y la eficiencia sólo en el periodo predestete. [ABSTRACT FROM AUTHOR]

This study aimed to estimate the response to selection through different selection indices between methane production and milk production and its components in specialized tropical, dual-purpose, and family dairy systems. Methane emissions were sampled during milking using the Guardian-NG gas monitor; milk samples were collected individually during methane sampling. DNA was extracted from the hair follicles of all the animals included in this study. The variance and covariance components were estimated using the mixed model methodology. Due to the incomplete genealogical information, molecular markers were used to build the genomic relationship matrix (Matrix G). The estimated heritability for methane emissions during milking was 0.18 and 0.32 for the univariate and bivariate analysis, respectively. The genetic correlation between the milk fat and protein percentages and methane emissions during milking was negative, -0.09 and -0.18, respectively. The response to selection, estimated through selection indices, demonstrated that it is feasible to reduce methane emissions up to 0.021 mg/L during milking in five generations without detriment to milk components. [ABSTRACT FROM AUTHOR]

The objective was to calculate the parameters, correlations and describe the genetic trends of reproductive traits in Holstein cattle from Mexico in three different periods of time, in females born between 2006 and 2019, using records of the Mexican Holstein association. The reproductive parameters calculated were: calving to first insemination interval (CFI), number of services per conception (NSC), days open (DO), interval between calving (IBC), and age at first calving (AFC). The components of variance were estimated using restricted maximum likelihood in an animal model, to calculate genetic parameters (narrow-sense heritability (h2), repeatability (r) and genetic correlations) and phenotypic correlations. Additive genetic variances and genetic values were also estimated in three periods of time (P1: 2006-2009, P2: 2010-2013 and P3: 2014-2017). The calculated heritabilities were from 4 to 9 % and the repeatabilities from 8 to 9 %, values close to previous reports for fertility traits. Phenotypic correlations were positive for almost all reproductive parameters and genetic correlations were positive over a wide range (0.13-0.99). Analyses by period showed changes, possibly derived from the influence of the import and use of germplasm from foreign bulls (mainly from the United States of America and Canada) which implement genomic selection and include fertility traits. The present research has made it possible to update the information on reproductive and genetic parameters in fertility traits that can be incorporated into national genetic evaluations. [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]