RESUMEN
The objective of this study was to identify genomic regions and genes associated with resistance to gastrointestinal nematodes in Australian Merino sheep in Uruguay, using the single-step GWAS methodology (ssGWAS), which is based on genomic estimated breeding values (GEBVs) obtained from a combination of pedigree, genomic, and phenotypic data. This methodology converts GEBVs into SNP effects. The analysis included 26,638 animals with fecal egg count (FEC) records obtained in two independent parasitic cycles (FEC1 and FEC2) and 1700 50K SNP genotypes. The comparison of genomic regions was based on genetic variances (gVar(%)) explained by non-overlapping regions of 20 SNPs. For FEC1 and FEC2, 18 and 22 genomic windows exceeded the significance threshold (gVar(%) ≥ 0.22%), respectively. The genomic regions with strong associations with FEC1 were located on chromosomes OAR 2, 6, 11, 21, and 25, and for FEC2 on OAR 5, 6, and 11. The proportion of genetic variance attributed to the top windows was 0.83% and 1.9% for FEC1 and FEC2, respectively. The 33 candidate genes shared between the two traits were subjected to enrichment analysis, revealing a marked enrichment in biological processes related to immune system functions. These results contribute to the understanding of the genetics underlying gastrointestinal parasite resistance and its implications for other productive and welfare traits in animal breeding programs.
Asunto(s)
Polimorfismo de Nucleótido Simple , Enfermedades de las Ovejas , Animales , Ovinos/parasitología , Ovinos/genética , Enfermedades de las Ovejas/genética , Enfermedades de las Ovejas/parasitología , Resistencia a la Enfermedad/genética , Estudio de Asociación del Genoma Completo , Infecciones por Nematodos/genética , Infecciones por Nematodos/veterinaria , Infecciones por Nematodos/parasitología , Australia , Recuento de Huevos de Parásitos/veterinaria , Parasitosis Intestinales/genética , Parasitosis Intestinales/veterinaria , Parasitosis Intestinales/parasitologíaRESUMEN
The objective of the study was to evaluate phenotypic resistance against gastrointestinal nematodes in Blackbelly, Pelibuey and Katahdin ewes before pregnancy in the humid tropics of Mexico. Individual faecal and blood samples were taken in 59 Pelibuey, 69 Blackbelly and 73 Katahdin ewes. The egg count per gram of faeces (EPG) of gastrointestinal nematodes (GINs) was determined. The percentage of packed cell volume (PCV) and body condition score (BCS) of each animal were also recorded. The ewes were segregated as susceptible, intermediate or resistant based on the EPG using the quartile method. The data were analysed using the general linear method, and the means between breeds were compared by Tukey's test. The relationships between the EPG, PCV and BCS were evaluated by Spearman correlation. The Katahdin ewes showed the highest EPG counts (3613.6 ± 5649) compared to the Blackbelly and Pelibuey ewes (576.1 ± 1009 and 56.8 ± 187, respectively, P < 0.01). The PCV values between breeds were similar (P > 0.05). The susceptible ewes had the highest EPG counts and the lowest PCV percentage (5069 ± 6404 and 22.8% ± 8.1% respectively) compared to the resistant ewes (P < 0.01). A higher percentage of Katahdin ewes were susceptible compared to the other breeds (P < 0.05). The main GIN species were Haemonchus contortus, Trichostrongylus colubriformis and Cooperia curticei. In conclusion, Katahdin ewes showed susceptibility to GIN compared to Blackbelly and Pelibuey ewes before the pregnancy period in the humid tropics of Mexico.
Asunto(s)
Infecciones por Nematodos/veterinaria , Enfermedades de las Ovejas/genética , Animales , Cruzamiento , Heces/parasitología , Femenino , Predisposición Genética a la Enfermedad , Hematócrito/veterinaria , México , Nematodos , Infecciones por Nematodos/genética , Infecciones por Nematodos/parasitología , Infecciones por Nematodos/patología , Recuento de Huevos de Parásitos/veterinaria , Embarazo , Ovinos , Enfermedades de las Ovejas/parasitología , Clima TropicalRESUMEN
This study compared the phenotypic susceptibility of Pelibuey and Katahdin female lambs against gastrointestinal nematodes (GINs) under grazing conditions in the hot humid tropics of Mexico. The study was performed during the rainy season (August to October, 2014). It included 27 Pelibuey and 12 Katahdin female lambs from 6 months of age and live weight of 21.0 ± 3.7 and 23.3 ± 3.6 kg, respectively. Lambs were reared free of GIN infection before the study. The study lasted 91 days. Animals were weighed and sampled (blood and feces) on days 0 and 28 and every 7 days onwards. Fecal samples were obtained to determine fecal eggs of GIN per gram (EPG), and blood samples were used to determine the packed cell volume (PCV), the peripheral eosinophil counts (PECs), and optical densities (ODs) for IgA. The EPG counts were significantly lower for Pelibuey lambs compared to Katahdin throughout the study (P < 0.001). Similarly, Pelibuey lambs had higher mean PCV (P < 0.01) and PEC (P < 0.05) than Katahdin lambs during the study. The total weight gain and OD for IgA were similar between breeds (P > 0.05). Negative associations (P < 0.05) between EPG and PCV or PEC were moderate to strong for the lambs of both breeds. No association was found between EPG and IgA. In conclusion, Pelibuey lambs showed phenotypic evidence of higher resistance to natural GIN infections compared to Katahdin lambs sharing the same grazing conditions in the hot humid tropics. The most accurate phenotypic markers to identify a difference in susceptibility were EPG and PEC.
Asunto(s)
Heces/parasitología , Predisposición Genética a la Enfermedad , Infecciones por Nematodos/veterinaria , Enfermedades de las Ovejas/parasitología , Animales , Femenino , Enfermedades Gastrointestinales/genética , Enfermedades Gastrointestinales/parasitología , Enfermedades Gastrointestinales/veterinaria , Hematócrito/veterinaria , México , Nematodos , Infecciones por Nematodos/genética , Recuento de Huevos de Parásitos/veterinaria , Lluvia , Ovinos , Enfermedades de las Ovejas/genética , Clima TropicalRESUMEN
Background: In sheep production systems based on grazing, gastrointestinal nematodes (GIN) are one of the main problemsfaced by farmers. The occurrence of anthelmintic resistance in GIN has endangered the productive activity of sheep, sothat one alternative has been through the selection of sheep. The selection programs are based on evaluation of parasitismby measuring the fecal egg counts (FEC) of GIN due to the high correlation between the FEC and worm burdens. Theidentification of resistant and susceptible lambs requires knowing the FEC after the infection. The aim of this research wasto determine the intra-breed variability on FEC of GIN in Katahdin x Pelibuey grazing sheep.Materials, Methods & Results: The experiment was conducted in Tabasco, Mexico in a warm humid climate. The studywas carried out in three stages: in stage I, the FEC was recorded in newly weaned lambs experimental infected with 1600infective larvae (L3) of Haemonchus contortus and Cooperia curticei (85% and 15% respectively). Twenty lambs weredrenched with albendazole and 20 more lambs were considered as control without any anthelmintic treatment. In stage IIacquired resistance was determined in the same animal group after a break period following the same treatments. In stageIII new lambs were introduced to paddocks and the FEC was recorded in their first infection. Every 15 days fecal sample,live weight and blood samples were taken to determine FEC, daily gain weight and packed cell volume. Data were analyzed with a model of repeated measures over time. In order to establish the level of anti-parasitic resistance in the lambs,a categorization of the lambs according to their FEC was performed based on the EPG mean and standard deviation. Subsequently another statistical analysis was performed by category to determine the EPG, PCV and DWG values per group.In primary infection, both lambs treated with albendazole and control group reached a maximum elimination at 32 days...(AU)
Asunto(s)
Animales , Ovinos/parasitología , Infecciones por Nematodos/genética , Infecciones por Nematodos/veterinaria , Haemonchus , Inmunidad Adaptativa , Humedad , Recuento de Huevos de Parásitos/veterinaria , Tracto Gastrointestinal/parasitologíaRESUMEN
Background: In sheep production systems based on grazing, gastrointestinal nematodes (GIN) are one of the main problemsfaced by farmers. The occurrence of anthelmintic resistance in GIN has endangered the productive activity of sheep, sothat one alternative has been through the selection of sheep. The selection programs are based on evaluation of parasitismby measuring the fecal egg counts (FEC) of GIN due to the high correlation between the FEC and worm burdens. Theidentification of resistant and susceptible lambs requires knowing the FEC after the infection. The aim of this research wasto determine the intra-breed variability on FEC of GIN in Katahdin x Pelibuey grazing sheep.Materials, Methods & Results: The experiment was conducted in Tabasco, Mexico in a warm humid climate. The studywas carried out in three stages: in stage I, the FEC was recorded in newly weaned lambs experimental infected with 1600infective larvae (L3) of Haemonchus contortus and Cooperia curticei (85% and 15% respectively). Twenty lambs weredrenched with albendazole and 20 more lambs were considered as control without any anthelmintic treatment. In stage IIacquired resistance was determined in the same animal group after a break period following the same treatments. In stageIII new lambs were introduced to paddocks and the FEC was recorded in their first infection. Every 15 days fecal sample,live weight and blood samples were taken to determine FEC, daily gain weight and packed cell volume. Data were analyzed with a model of repeated measures over time. In order to establish the level of anti-parasitic resistance in the lambs,a categorization of the lambs according to their FEC was performed based on the EPG mean and standard deviation. Subsequently another statistical analysis was performed by category to determine the EPG, PCV and DWG values per group.In primary infection, both lambs treated with albendazole and control group reached a maximum elimination at 32 days...
Asunto(s)
Animales , Haemonchus , Inmunidad Adaptativa , Infecciones por Nematodos/genética , Infecciones por Nematodos/veterinaria , Ovinos/parasitología , Recuento de Huevos de Parásitos/veterinaria , Tracto Gastrointestinal/parasitología , HumedadRESUMEN
Cytokines are small cell-signaling proteins that play an important role in the immune system, participating in intracellular communication. Four candidate genes of the cytokine family (IL2, IL4, IL13, and IFNG) were selected to identify Single Nucleotide Polymorphisms (SNPs) that might be associated with resistance to gastrointestinal endoparasites in goats. A population of 229 goats, F2 offspring from an F1 intercross was produced by crossing pure Saanen goats, considered as susceptible to gastrointestinal endoparasites, with pure Anglo-Nubian goats, considered resistant. Blood was collected for DNA extraction and fecal samples were also collected for parasite egg count. Polymorphisms were prospected by sequencing animals with extreme phenotype for fecal egg count (FEC) distribution. The association between SNPs and phenotype was determined by using the Fisher exact test with correction for multiple tests. Three of the 10 SNPs were identified as significant (P ≤ 0.03). They were found in intron 1 of IL2 (ENSBTA00000020883), intron 3 of IL13 (ENSBTA00000015953) and exon 3 of IFNG (ENSBTA00000012529), suggesting an association between them and gastrointestinal endoparasite resistance. Further studies will help describe the effects of these markers accurately before implementing them in marker assisted selection. This study is the pioneer in describing such associations in goats.
Asunto(s)
Enfermedades Intestinales/genética , Infecciones por Nematodos/genética , Polimorfismo de Nucleótido Simple , Alelos , Animales , Citocinas/genética , Sitios Genéticos , Genotipo , Cabras , Enfermedades Intestinales/parasitología , Infecciones por Nematodos/parasitologíaRESUMEN
The resistance to infestations by ectoparasites and infections by gastrointestinal nematodes was studied in 45 animals (males and females) of two genetic groups: purebred Nelore (NI, n=28) and Three-Cross (1/2 Angus+1/4 Canchim+1/4 Nelore - TC, n=17). The animals were monitored for 24 months, during which they were left to graze in tropical pastures without receiving treatment for parasites. Each month the animals were examined for infestations by external parasites, to count the numbers of cattle ticks Rhipicephalus microplus with diameter greater than 4.5mm present on the left side, horn flies (Haematobia irritans) present in the lumbar region and botfly larvae (Dermatobia hominis) present on the entire body. The H. irritans counts were performed with the aid of digital photographs. At the time of examination, fecal samples were collected to count the eggs per gram (EPG) and to perform coprocultures, and peripheral blood samples were drawn to determine the packed cell volume (PCV) and to count the eosinophils. For statistical analysis, the count data were transformed into log10 (n+1), where n is the number of parasites. For PCV, significant effects (P<0.05) were found for collection month (CO), genetic group (GG) and gender (SX), with means and respective standard errors of 41.5 ± 0.65% for the NI animals, 39.3 ± 0.83% for the TC, 41.5 ± 0.72% for the females and 39.3 ± 0.77% for the males. Regarding the eosinophil counts, only the effect of sex was significant (P<0.01), with means and respective standard errors of 926.0 ± 46.2/µL, for males and 1088.0 ± 43.8/µL of blood, for females. The NI animals presented lower mean counts for all the external parasites compared to the TC animals (P<0.01). For ticks, the transformed means followed by standard errors for the NI and TC animals were 0.06 ± 0.01 and 0.34 ± 0.02, while for horn flies these were 0.92 ± 0.05 and 1.36 ± 0.06 and for botfly larvae they were 0.05 ± 0.03 and 0.45 ± 0.05, respectively. The average EPG values were only influenced by CO (P<0.01). The coprocultures revealed the presence of the following endoparasites: Haemonchus spp., Cooperia spp., Oesophagostomum spp. and Trichostrongylus spp., the last in smaller proportion. There were no significant differences between the genetic groups for the endoparasite loads, except for Cooperia spp., which were present in greater number (P<0.05) in the NI group. The results obtained in this experiment confirm previous findings of greater susceptibility of the Nelore breed to Cooperia spp. and high resistance to ectoparasites.
Asunto(s)
Enfermedades de los Bovinos/parasitología , Infestaciones Ectoparasitarias/veterinaria , Enfermedades Gastrointestinales/veterinaria , Predisposición Genética a la Enfermedad , Infecciones por Nematodos/veterinaria , Animales , Brasil/epidemiología , Bovinos , Enfermedades de los Bovinos/epidemiología , Enfermedades de los Bovinos/genética , Infestaciones Ectoparasitarias/epidemiología , Infestaciones Ectoparasitarias/genética , Femenino , Enfermedades Gastrointestinales/epidemiología , Enfermedades Gastrointestinales/genética , Enfermedades Gastrointestinales/parasitología , Masculino , Infecciones por Nematodos/epidemiología , Infecciones por Nematodos/genética , Estaciones del Año , Factores de TiempoRESUMEN
We estimated the genetic parameters for BW, reproduction, and parasite resistance traits to implement a breeding program for the Creole goat. The traits were preweaning BW at 70 d of age (BW70d), BW at 11 mo of age (BW11), fecal egg count at 11 mo of age (FEC11) for all animals, packed cell volumes of lactating does (PCV), and their fertility (FER) and litter size (LS). We analyzed about 30 yr of data, which included 18,450 records on 11,970 animals from the INRA experimental flock in Guadeloupe (French West Indies). Heritability estimates were low for reproduction traits (0.11 ± 0.02 for LS and FER) to moderate for production traits (0.32 ± 0.03 for BW11; 0.20 ± 0.03 and 0.08 ± 0.02 for the direct and maternal heritability estimates of BW70d, respectively). Heritability estimates for gastrointestinal nematode resistance traits were situated in an intermediate range (0.13 ± 0.05 for PCV and 0.18 ± 0.04 for FEC11). Genetic correlations between FER, PCV, BW11, and the maternal effect of BW70d were altogether positive, whereas LS and FEC11 were almost uncorrelated phenotypically and genetically. These correlations are very favorable for setting up a breeding program, making it possible to improve BW, reproduction, and parasite resistance traits simultaneously.
Asunto(s)
Peso Corporal/fisiología , Fertilidad/fisiología , Cabras/fisiología , Modelos Genéticos , Infecciones por Nematodos/veterinaria , Carácter Cuantitativo Heredable , Animales , Animales Recién Nacidos , Peso Corporal/genética , Femenino , Fertilidad/genética , Cabras/genética , Cabras/parasitología , Guadalupe , Hematócrito/veterinaria , Tamaño de la Camada/genética , Masculino , Infecciones por Nematodos/genética , Infecciones por Nematodos/parasitología , Recuento de Huevos de Parásitos/veterinaria , EmbarazoRESUMEN
Resistance to natural infection by gastrointestinal nematodes was compared in 67 female calves of the following genetic groups: Nelore (NX); 1/2 Senepol+1/2 Nelore (SN); and 1/2 Aberdeen Angus+1/2 Nelore (AN). The NX (n=26), SN (n=23) and AN (n=18) animals were monitored for 14 months, during which they remained without treatment, allowed to graze in a tropical environment. Eggs per gram of feces (EPG), coprocultures and packed cell volume (PCV) were carried out monthly. No significant effects of the interaction between the genetic groups and month/year of collection and the genetic group on the EPG were found, but there was a significant influence of the month of collection (P<0.01). The monthly PCV measurements did not differ for the animals of the three genetic groups and there was no association found between the EPG and PCV. The animals of the SN and NX groups showed similar numbers of EPG with results zero, while for the AN group these numbers were significantly lower (P<0.05). Although the NX group had a large number of EPG with results zero, it also contained many animals with high counts, meaning this group had higher averages during the entire study period. The following nematode genera were found in the coprocultures: Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus, the latter in smallest proportion. There was no significant difference between the genetic groups for averages of all parasites identified, except Cooperia, which were present in higher numbers in the animals of the NX group (P<0.05). The results obtained in this experiment suggest that the use of Bos taurus x Bos indicus crossbreeds can be a good strategy to reduce the use of chemical control in Brazil.
Asunto(s)
Enfermedades de los Bovinos/genética , Enfermedades de los Bovinos/parasitología , Inmunidad Innata/genética , Infecciones por Nematodos/veterinaria , Animales , Brasil , Bovinos , Heces/parasitología , Femenino , Nematodos/clasificación , Nematodos/aislamiento & purificación , Infecciones por Nematodos/genética , Infecciones por Nematodos/parasitología , Recuento de Huevos de Parásitos , Lluvia , Temperatura , Factores de TiempoRESUMEN
This trial was carried out in Piracicaba, São Paulo State, Brazil, to comparatively evaluate the degree of resistance to naturally acquired gastrointestinal nematode infections in sheep of the following genetic groups: purebred Santa Ines (SI), SI crossbred with Dorper (DO x SI), Ile de France (IF x SI), Suffolk (SU x SI), and Texel (TE x SI). Fifteen ewes from each group were raised indoors until 12 months of age. At this age, they were moved to pasture that was naturally contaminated by nematode infective larvae and were evaluated from December to May, 2007. Rainfall ranged from 267 mm in January to 37 mm in April. Maximum and minimum mean temperatures ranged from 32.5 degrees C to 19.0 degrees C in March and from 25.9 degrees C to 12.8 degrees C in May. There was an increase in the mean number of eggs per gram of feces (EPG) after animals were placed on pasture with significant difference between the SI (80 EPG) and IF x SI (347 EPG) groups in January; and the DO x SI (386 EPG) and TE x SI (258 EPG) groups in May. The highest mean fecal egg count (FEC), 2073 EPG, was recorded for the TE x SI group in February. All groups showed a progressive reduction in body weight throughout the experiment of 12.0% (TE x SI) to 15.9% (SU x SI). In general, the animals with the highest FEC presented the lowest packed cell volumes (PCV); the highest correlation coefficient between FEC x PCV occurred in the SU x SI sheep in January (r=-0.70; P<0.01). Similarly, there was an inverse relationship between FEC and blood eosinophil values, with the highest correlation coefficient in the TE x SI sheep in February (r=-0.64; P<0.05). Immunoglobulin G (IgG) levels against Haemonchus contortus antigens increased in all groups as a result of the exposure to parasites and remained relatively constant until the end of the study, with the exceptions of SU x SI and TE x SI, which showed a rise in IgG levels during the last sampling that coincided with a reduction in mean FEC. In conclusion, crossbreeding Santa Ines sheep with any of the breeds evaluated can result in a production increase and the maintenance of a satisfactory degree of infection resistance, especially against H. contortus and Trichostrongylus colubriformis, the major nematodes detected in this flock.
Asunto(s)
Cruzamiento , Enfermedades Gastrointestinales/genética , Enfermedades Gastrointestinales/parasitología , Inmunidad Innata/genética , Nematodos/fisiología , Infecciones por Nematodos/veterinaria , Enfermedades de las Ovejas/genética , Animales , Peso Corporal , Heces/parasitología , Femenino , Hematócrito , Larva , Masculino , Infecciones por Nematodos/genética , Recuento de Huevos de Parásitos , OvinosRESUMEN
Gastrointestinal parasitism of Zebu crossbred (Z), Hereford (H), and Hereford X Brahman (HB) weaned steer calves was observed from March 1985 to May 1986. Three groups of 60 calves were randomised and in each group the three breeds were equally present. Calves in GI were untreated, in GII were treated strategically and in GIII treated monthly with anthelmintic. The effects of anthelmintic treatments on the growth of cattle were assessed by comparing mean live-weight gain (MLG) responses of treated and untreated calves grazing the same permanent pasture. Worm recovery and egg counts increased from autumn to winter. After abundant July rainfalls, herbage infective larvae (L3) and worm burdens (mainly Ostertagia) reached the highest levels and Z calves presented symptoms of clinical parasitism. After high availability of L3 in spring, L3 and egg counts decreased to the end of the study. From the end of winter until summer a high percent of inhibited Ostertagia EL4 was seen. Blood samples showed reduced serum copper lower levels for GI. MLG responses of Z treated calves were significantly higher during the autumn-spring and summer-autumn periods. MLG responses of treated H calves were significant only during the winter-spring period. For HB calves there were no significant MLG responses during any period. The highest monthly treatment response was observed during winter and early spring. All strategic treatments gave significant MLG responses in spring and late summer. Initial effects of parasitism, from autumn until early spring had the greatest consequences in current and later productivity. For Z calves herbage L3, worm burdens, egg counts and MLG responses were higher than for H and HB calves. The Z breed were significantly heavier (+22.7%) at the end of the experiment in GIII than in GI. Similar trends were recorded, significantly, for H breed (+17.7%) and not statistically significant for HB (+12.7%). Under our temperate conditions it seems that H and HB calves showed greater capacity to resist nematode infection than Z calves.
Asunto(s)
Antihelmínticos/uso terapéutico , Enfermedades de los Bovinos/epidemiología , Cruzamientos Genéticos , Parasitosis Intestinales/veterinaria , Infecciones por Nematodos/veterinaria , Animales , Argentina/epidemiología , Cruzamiento , Bovinos , Enfermedades de los Bovinos/genética , Enfermedades de los Bovinos/prevención & control , Cobre/sangre , Heces/parasitología , Parasitosis Intestinales/epidemiología , Parasitosis Intestinales/genética , Parasitosis Intestinales/prevención & control , Masculino , Infecciones por Nematodos/epidemiología , Infecciones por Nematodos/genética , Infecciones por Nematodos/prevención & control , Recuento de Huevos de Parásitos/veterinaria , Distribución Aleatoria , Estaciones del Año , Aumento de PesoRESUMEN
Mice which had been selectively reared over six generations for high (H) and low (L) immune responsiveness to N. dubius (Sitepu and Dobson, 1982) were infected with Salmonella typhimurium and N. brasiliensis to examine the specificity of the selection process for heterologous infections. H mice were marginally more susceptible than L mice to S. typhimurium, whereas H mice were more resistant to infection with N. brasiliensis than L mice. Both H and L mice were protected against N. dubius following immunization with N. brasiliensis larvae.
Asunto(s)
Infecciones por Nematodos/inmunología , Salmonelosis Animal/inmunología , Animales , Femenino , Masculino , Ratones , Infecciones por Nematodos/genética , Nippostrongylus , Salmonelosis Animal/genética , Salmonella typhimuriumRESUMEN
We investigated the IgE-antibody response in 36 inbred mouse strains during infection with Nippostrongylus brasiliensis. With regard to the N. brasiliensis-specific IgE-antibody activity responder and nonresponder mice were obtained. Mice with the H-2-f haplotype (A.CA, B10.M, A.TFR 5) are high specific responders. It is suggested that one Ir gene for the N. brasiliensis-induced IgE-antibody response is localized within the K to J region of the mouse major histocompatibility complex. To obtain a medium IgE-antibody response it appears that a complementation between two Ir genes is necessary. An additional genetic control beyond the H-2 complex cannot be excluded. As to the total nonspecific serum IgE levels the parasitic infection leads to a 20- to 40-fold increase in high and low specific responder strains as well. Pretreatment of high responder mice (A.TFR 5, B10.M) with sera that were obtained from normal or complete Freund's adjuvant treated low (B10.G) and nonresponder (A.TFR 1) mice led to significant inhibition or enhancement of the N. brasiliensis-specific IgE-antibody response.