Genetic diversity of SNPs associated with candidate genes for heat stress in Coreño Creole cattle in Mexico.

Mexican Coreño Creole cattle are an important genetic resource adapted to local environmental conditions, so the study of their genetic diversity is essential to know their status and implement conservation programs and their use for crossbreeding. This study evaluated the genetic diversity of heat stress tolerance characteristics of Coreño Creole cattle, and a gene ontology enrichment was performed to know the biological processes in which candidate genes are involved. A total of 48 samples from three localities of Nayarit were genotyped using 777 K Illumina BovineHD BeadChip and 34 single nucleotide polymorphisms associated with candidate genes were selected. Genetic diversity was analyzed using allelic frequencies, expected heterozygosity (He), and Wright's fixation index (FST) using PLINK v1.9 software. Candidate genes were uploaded to the open-source GOnet for pathway analysis and linkage to biological processes. Coreño Creole cattle showed low genetic diversity (He = 0.35), the average FST obtained was 0.044, and only eight markers had allele frequencies higher than 0.80 in the three locations. We found that the genes GOT1 and NCAD are related in the biological processes of stress response, cell differentiation, and homeostatic process. The results revealed that Coreño Creole cattle have low genetic diversity; this could be due to the isolation of these populations.

Effect of the percentage of Bos taurus inheritance on the fertility of Holstein×Zebu and Brown Swiss×Zebu cows in the Mexican tropics

Background: No dairy breed or crossbreed has superior overall performance in all environments; therefore, it is necessary to determine which crossbreed is the most suitable for the Mexican tropic and what proportion of European breed is optimum for reproduction. Objective: To assess the effect of the proportion of Bos taurus (Bt) genes on reproductive performance of Holstein×Zebu (HZ) and Brown Swiss×Zebu (BZ) cows, and compare reproductive performance of these genotypes in a dual- purpose production system. Methods: Cows were maintained in a rotational grazing system on African star grass (Cynodon plectostachyus) in Veracruz, Mexico. Cows were milked twice daily. Calves were kept tied to the side of their dams while the cows were milked. Results: The percentage of Bt genes did not affect (p>0.05) fertility traits (age at first calving, days to first service after calving, services per conception, conception rate at first service, days open until conception, gestation length, and calving interval) of BZ cows. In contrast, HZ cows with less than 75% Holstein (H) genes were 0.3 years younger (p<0.05) at first calving and had 39.8 fewer days open (p<0.05) than HZ cows with 75% H genes or more. In addition, the calving interval of HZ cows with less than 75% H genes was 44.8 days shorter (p<0.05) than that of HZ cows with 75% H genes or more. The HZ cows had five fewer days pregnant and were 22.8 kg heavier at calving (p<0.05) than BZ cows. Conclusions: The effect of the percentage of Bt genes on cow fertility depends on the dairy breed used. In general, BZ and HZ cows present similar reproductive performance.

Antecedentes: Ninguna raza lechera o cruce tiene un desempeño general superior en todos los ambientes; por lo tanto, es necesario determinar cuál cruce lechero es más apropiado en el trópico mexicano y qué proporción de raza europea es óptima para la reproducción. Objetivo: Evaluar el efecto de la proporción de genes Bos taurus (Bt) en el desempeño reproductivo de vacas cruzadas Holstein×Cebú (HC) y Pardo Suizo×Cebú (PC), y comparar el desempeño reproductivo de estos dos genotipos en un sistema de producción doble propósito. Métodos: Las vacas se mantuvieron en un sistema de pastoreo rotacional en zacate Estrella de África (Cynodon plectostachyus) en Veracruz, México. Las vacas se ordeñaron dos veces al día. Los becerros se mantuvieron atados, a un costado de sus madres mientras éstas se ordeñaron. Resultados: El porcentaje de genes Bt no afectó (p>0,05) ninguna característica de fertilidad (edad a primer parto, días a primer servicio después del parto, servicios por concepción, tasa de preñez a primer servicio, días abiertos a la concepción, duración de la gestación, e intervalo entre partos) de las vacas PC. En contraste, las vacas HC con menos de 75% de genes Holstein (H) fueron 0,3 años más jóvenes (p<0,05) al primer parto y tuvieron 39,8 días abiertos menos (p<0,05) que las vacas HC con 75% de genes H o más. Además, el intervalo entre partos de las vacas HC con menos de 75% de genes H fue 44,8 días más corto (p<0,05) que el de las vacas HC con 75% de genes H o más. Las vacas HC tuvieron cinco días de gestación menos y fueron 22,8 kg más pesadas al parto (p<0,05) que las PC. Conclusiones: El efecto del porcentaje de genes Bt sobre la fertilidad de la vaca depende de la raza lechera usada. En general, las vacas PC y HC tienen similar desempeño reproductivo.

Antecedentes: Nenhuma raça ou cruza leiteira tem desempenho geral superior em todos os ambientes; portanto, é necessário determinar qual cruza leiteira é mais apropriada no trópico mexicano e qual proporção da raça europeia é ideal para a reprodução das vacas. Objetivo: Avaliar o efeito da proporção de genes Bos taurus (Bt) no desempenho reprodutivo de vacas Holandês×Zebu (HZ) e Pardo Suíço×Zebu (PZ), e comparar o desempenho reprodutivo desses dois genótipos em sistema de produção de dupla aptidão. Métodos: As vacas foram mantidas em sistema de pastoreio rotacional em capim Estrela de África (Cynodon plectostachyus) em Veracruz, México. As vacas foram ordenhadas duas vezes por dia. Os bezerros foram mantidos ao lado de suas mães enquanto eram ordenhadas. Resultados: A porcentagem dos genes Bt não afetou (p>0,05) nenhuma característica de fertilidade (idade ao primeiro parto, número de dias para o primeiro serviço pós-parto, serviços por concepção, taxa de prenhes no primeiro serviço, dias abertos, período de gestação e intervalo entre partos) das vacas PZ. Em contraste, vacas HC com menos de 75% dos genes Holandês (H) eram 0,3 anos mais jovens (p<0,05) no primeiro parto e tiveram 39,8 dias abertos a menos (p<0,05) do que as vacas HZ com 75% ou mais dos genes H. Além disso, o intervalo de parto das vacas HZ com menos de 75% dos genes H foram 44,8 dias mais curtos (p<0,05) do que as vacas HZ com 75% ou mais de genes H. As vacas HZ tiveram cinco dias de gestação a menos e foram 22,8 kg mais pesadas no parto (p<0,05) do que as PZ. Conclusões: O efeito da porcentagem de genes Bt na fertilidade da vaca dependeu da raça leiteira utilizada. Em geral, as vacas PZ e HZ tiveram desempenho reprodutivo semelhante.

Comparison of models for lactation curves of Holstein, Brown Swiss, and F1 crossbred cows under subtropical conditions.

Tropical and subtropical milk production herds in Mexico generally generate different types of milk-yield records as milk yield per month and mean production per month. Lactation curves generated by these types of records may contribute to understand milk production in the tropical regions of Mexico. The aim of this study was to compare five lactation-curve models fitted to two types of milk-yield records of Holstein, Brown Swiss, and F1 crossbred cows under subtropical conditions. The two types of records (n = 3756) used were: (1) milk yield per month (TR) and 2) mean production per months (MR). Goodness-of-fit statistics, including Akaike's information criterion (AIC) and root mean square error (RMSE), were applied to compare the models for each type of records. The Brody model provided the best goodness-of-fit when using monthly milk-yield records, while the Wilmink model provided the best goodness-of-fit for lactation milk-yield records. The RMSE and AIC values were similar between datasets. The final third of the lactation curve showed a little difference between model predictions in both datasets. The comparison of several models was useful to better describe the actual lactation curves of the herd. The Wood model may be adequate to compare information as a reference with other models for decision making process at milk production.

Copy Number Variation Mapping and Genomic Variation of Autochthonous and Commercial Turkey Populations.

This study aims at investigating genomic diversity of several turkey populations using Copy Number Variants (CNVs). A total of 115 individuals from six Italian breeds (Colle Euganei, Bronzato Comune Italiano, Parma e Piacenza, Brianzolo, Nero d'Italia, and Ermellinato di Rovigo), seven Narragansett, 38 commercial hybrids, and 30 Mexican turkeys, were genotyped with the Affymetrix 600K single nucleotide polymorphism (SNP) turkey array. The CNV calling was performed with the Hidden Markov Model of PennCNV software and with the Copy Number Analysis Module of SVS 8.4 by Golden Helix®. CNV were summarized into CNV regions (CNVRs) at population level using BEDTools. Variability among populations has been addressed by hierarchical clustering (pvclust R package) and by principal component analysis (PCA). A total of 2,987 CNVs were identified covering 4.65% of the autosomes of the Turkey_5.0/melGal5 assembly. The CNVRs identified in at least two individuals were 362-189 gains, 116 losses, and 57 complexes. Among these regions the 51% contain annotated genes. This study is the first CNV mapping of turkey population using 600K chip. CNVs clustered the individuals according to population and their geographical origin. CNVs are known to be indicators also of adaptation, as some researches in different species are suggesting.

The nematophagous fungus Duddingtonia flagrans reduces the gastrointestinal parasitic nematode larvae population in faeces of orally treated calves maintained under tropical conditions-Dose/response assessment.

This research assessed the dose/response to Duddingtonia flagrans chlamydospores (Df-C) administered to calves naturally infected with gastrointestinal nematodes (GINs), and its effect in reducing the infective larvae (L3) population in faeces in a farm in the Mexican tropics. Forty zebu calves, between 6 and 12 months of age, were randomly distributed into four groups of 10 calves. One control and three groups treated with different oral doses of Df-C based on their body weight (BW) were established as follows: group 1 (control); group 2, 0.250 × 106Df-C per kg/BW; group 3, 0.5 × 106Df-C per kg/BW and group 4, 1 × 106Df-C per kg/BW. The fungal doses were administered daily for 10 days. Every group was confined to individual pens, and they received a nutritional regime based on Buffel grass, concentrated supplement and water ad libitum. Every third day, starting one week before treatments, faeces were taken from the rectum of each animal to determine the number of eggs per g of faeces (epg) through the McMaster technique. Four coprocultures of 20 g each from each individual faecal sample were prepared and incubated for 14 days. The efficacy of the treatments was based on the mean of the GIN L3 recovered from coprocultures of the different groups. Data were analysed using a completely randomized design through an ANOVA analysis, followed by a Duncan multiple range test. The efficacy of treatments was expressed as the larval reduction rate. High variation in the epg in the different groups along the experiment was recorded. The reduction in the GIN L3 population was observed from the 4 to 11 day post-treatment in the three assessed doses. Results in group 2 (lowest fungal dose), showed 88.5, 57.6, 55.9 and 30% (58% overall reductions) in the GIN L3 in the faeces of animals 4, 7, 9 and 11 days post-treatment, respectively. In group 3 (medium fungal dose), 95.8, 80.4, 63.4 and 52.7% GIN L3 reductions (73% overall reduction) were recorded, respectively. At the highest Df-C dose used (1 × 106 per kg/BW), the results were 88.9, 78.0, 59.3 and 67.3% (73.5% overall reduction), respectively (p < 0.05). The species of identified nematodes through L3 morphometric and molecular taxonomy were Cooperia spp. and H. contortus. From the three Df-C assessed doses, the medium dose (0.5 × 106Df-C per kg/BW) was sufficient to substantially reduce the GIN L3 in zebu calves maintained under conditions in the Mexican tropics.

Genetic parameters for scrotal circumference, frame score and yearling weight of Mexican Charolais and Charbray young bulls / Parámetros genéticos de circunferencia escrotal, talla corporal y peso al año de toros jóvenes mexicanos Charolais y Charbray / Parâmetros genéticos de perímetro escrotal, escore de frame e peso ao ano de idade de touros jovens mexicanos Charolês e Charbray

Abstract Background: Knowledge of genetic correlations and the economics of traits are essential to decide which traits should be used as selection criteria. Objective: To estimate heritabilities and genetic, environmental, and phenotypic correlations, and direct (DRS) and correlated (CRS) responses to selection by scrotal circumference (SC), frame score (FS), and yearling weight (YW) of Mexican Charolais (CH), and Charbray (CB) young bulls. Methods: Actual SC, height and YW records (10,078 for CH, and 500 for CB) were adjusted to 365 d. The 0.0505 adjustment factor recommended by the Beef Improvement Federation was used to obtain the 365-d adjusted SC for both breeds. Height and age records were used to obtain FS. Data were analyzed using a three-trait animal model. The animal model for each trait included bull breed, contemporary group (groups of young bulls born in the same herd, year, and season of the year), and age of dam as a linear covariate as fixed effects, and direct additive genetic and residual as random effects. Results: Heritability estimates for SC, FS and YW were 0.21 ± 0.04, 0.25 ± 0.04, and 0.29 ± 0.04, respectively. The genetic correlation between YW with SC was 0.37 ± 0.16, and between YW with FS was 0.42 ± 0.16. The estimate of genetic correlation between SC and FS was low and positive (0.15 ± 0.14). The DRS was 0.38 cm, 0.18 units, and 8.30 kg for SC, FS and YW. The CRS was 0.16 cm, and 0.08 units for SC and FS from indirect selection on YW. Conclusions: Direct selection for YW is expected to be effective. Indirect selection for SC and FS based on YW would not be expected to be as effective as direct selection for improving SC and FS.

Resumen Antecedentes: el conocimiento de las correlaciones genéticas y el aspecto económico de las características son necesarios para decidir qué características usar como criterios de selección. Objetivo: estimar las heredabilidades y correlaciones genéticas, ambientales y fenotípicas, y respuesta directa (DRS) y correlacionada (CRS) a la selección por circunferencia escrotal (SC), talla corporal (FS), y peso al año (YW) de toros jóvenes mexicanos Charolais (CH), y Charbray (CB). Métodos: registros (10.078 para CH y 500 para CB) de SC, altura y YW se ajustaron a 365 d. El factor de ajuste de 0,0505 recomendado por la Beef Improvement Federation se usó para obtener la SC ajustada a 365 d para ambas razas. Registros de altura y edad del animal se usaron para calcular FS. Los datos se analizaron usando un modelo animal para tres características. El modelo animal para cada característica incluyó raza del toro, grupo contemporáneo (grupos de toros jóvenes nacidos en el mismo hato, año y época del año) y edad de la madre como covariable lineal como efectos fijos, y el genético aditivo directo y el error como efectos aleatorios. Resultados: los estimadores de heredabilidad de SC, FS y YW fueron 0,21 ± 0,04, 0,25 ± 0,04 y 0,29 ± 0,04, respectivamente. La correlación genética de YW con SC fue 0,37 ± 0,16, y de YW con FS fue 0,42 ± 0,16. El estimador de la correlación genética entre SC y FS fue bajo y positivo (0,15 ± 0,14). La DRS fue 0,38 cm, 0,18 unidades, y 8,30 kg para SC, FS y YW. La CRS fue 0,16 cm y 0,08 unidades para SC y FS al seleccionar YW. Conclusiones: se espera que la selección directa de YW sea efectiva. La selección indirecta de SC y FS basada en YW no se espera que sea tan efectiva como la selección directa para mejorar SC y FS.

Resumo Antecedentes: o conhecimento das correlações genéticas, e aspecto econômico de as características são necessário para decidir que características usar como critérios de seleção. Objetivo: estimar herdabilidades e correlações genéticas, ambientais e fenotípicas, e resposta direta (DRS), e correlacionada (CRS) à seleção do perímetro escrotal (SC), escore de frame (FS), e peso ao ano de idade (YW) de touros jovens mexicanos Charolês (CH), e Charbray (CB). Métodos: registros (10.078 para CH e 500 para CB) de SC, altura e YW foram ajustados a 365 d. O fator de ajuste 0,0505 recomendado por a Beef Improvement Federation foi usado para obter o SC ajustado aos 365 d para ambas raças. Registros de altura na garupa e idade do animal foram usados para obter o FS. Os dados foram analisados usando um modelo animal para três características. O modelo animal para cada característica incluiu raça do touro, grupo contemporâneo (grupos de touros jovens nascidos no mesmo fazenda, ano e época do ano) e idade materna como covariável linear como efeitos fixos, e genético aditivo direto e o erro como efeitos aleatórios. Resultados: as estimativas de herdabilidade para SC, FS e YW foram 0,21 ± 0,04, 0,25 ± 0,04 e 0,29 ± 0,04, respetivamente. A correlação genética do YW com SC foi 0,37 ± 0,16, e de YW com FS foi 0,42 ± 0,16. A estimativa da correlação genética entre SC e FS foi baixa e positiva (0,15 ± 0,14). A DRS foi 0,38 cm, 0,18 unidades, e 8,30 kg para SC, FS e YW. A CRS foi 0,16 cm e 0,08 unidades para SC e FS al selecionar YW. Conclusões: espera-se que a seleção direta do YW seja eficaz. A seleção indireta de SC e FS com base no YW não se espera que seja tão efetiva como a seleção direta para melhorar SC e FS.