Effect of the FecX(R) polymorphism in the bone morphogenetic protein 15 gene on natural or equine chorionic gonadotropin-induced ovulation rate and litter size in Rasa Aragonesa ewes and implications for on-farm application

A new mutation in the bone morphogenetic protein 15 (BMP15) gene (FecX(R) allele) causing increased prolificacy in heterozygous (R+) and sterility in homozygous ewes has been recently described in Rasa Aragonesa, a low-prolificacy Mediterranean breed. The current study determined, first, the effect of this polymorphism on natural and eCG-induced ovulation rate (OR) and the effect of eCG dose on reproductive performance; and second, its effect on prolificacy and its interaction with progestagen + eCG treatment on farms, which have not been reported to date. The FecX(R) allele increased OR by 0.44 and 0.63 ovulations in young (n = 91) and adult (n = 84) R+ ewes, respectively (both, P < 0.01), increments less than reported in prolific breeds carrying other mutations in BMP15. When the standard dose of eCG used on farms (480 IU) was applied to R+ ewes (n = 36), an extremely high OR (3.95) was recorded, which was accompanied by greater partial failure of multiple ovulations (PFMO). On the contrary, OR using 240 IU in R+ ewes (2.90; n = 35) was similar to 480 IU in wildtype (++) ewes (2.82; n = 48; both P < 0.01 when compared with 480 IU in R+ ewes). No differences were found in the birth weight of the offspring between R+ and ++ eCG-stimulated ewes within the same litter size. To validate the genealogy identification on farms, PCR genotyping was carried out in 1,667 ewes from 4 elite flocks, resulting in a negligible misclassification of R+ ewes, which demonstrated that identification by genealogy is a reliable tool to identify FecX(R) ewes within the breeding program. In recorded farms, the natural litter size of ++ ewes (1.34, n = 599,160 lambing records) was increased due to the FecX(R) allele by 0.35 lambs (P < 0.0001, n = 6,593 lambing records). A similar increase (0.30) was observed when comparing ++ and R+ ewes treated with 480 IU of eCG (P < 0.0001, n = 62,055 and n = 866, respectively). When applying 480 IU of eCG to R+ ewes, the increase in prolificacy was only due to increased percentages of triplets (P < 0.001) and quadruplets (P < 0.0001), but not of twin births. In conclusion, the favorable reproductive performance of R+ ewes, with 0.63 extra ovulations and 0.35 extra lambs per lambing ewe, is responsible for the increased interest in the use of this polymorphism. Nevertheless, care must be taken in the application of eCG to R+ ewes, with the current results showing that the standard dose increases prolificacy by only increasing triple and higher-order births.

Success of medical therapy in a rare case of cecal ameboma

Colitis caused by Entamoeba histolytica (EH) is prevalent in developing countries. Clinical presentation ranges from mild diarrhoea episodes to dysentery and liver abscess. Ameboma, a complication caused by EH invasion of the intestinal wall, is a rare presentation of amebiasis, occurring approximately in 1.5% of cases. Because of its insidious and variable clinical presentation only few cases are diagnosed previous to surgical intervention. We report a 52 years old Mexican-mestizo female, presenting with a pain-less right lower quadrant abdominal mass and diagnosed of cecal ameboma prior to surgery by colonoscopy and histopathologic examination. The present case highlights the importance of early diagnosis and medical therapy with antiparasitic drugs in order to avoid complications that could lead these patients to unnecessary surgical management.

Ovine alpha-amylase genes: isolation, linkage mapping and association analysis with milk traits

On the basis of comparisons between cattle and sheep genome mapping information the ovine alpha-amylase gene was examined as a possible genetic marker for milk traits in sheep. The objective of the present study was to isolate, map and determine whether this gene is a candidate gene for milk traits. DNA fragments (832 and 2360 bp) corresponding to two different AMY genes were isolated, and one SNP in intron 3 and one GTG deletion in exon 3 of the 2360 bp DNA fragment were found. The 2360 bp ovine AMY DNA fragment was located on chromosome 1 by linkage mapping using the International Mapping Flock. No association was found between estimated breeding values for milk yield, protein and fat contents and AMY genotypes in a daughter design comprising 13 Manchega families with an average of 29 daughters (12-62) per sire.

Association of the heart fatty acid-binding protein (FABP3) gene with milk traits in Manchega breed sheep

The ovine fatty acid-binding protein type 3 gene has been chosen as a functional candidate gene for milk traits. Two different single nucleotide polymorphisms (SNPs) of ovine FABP3 gene have been tested in a daughter design comprising 13 families. No association was found between estimated breeding values for milk yield, protein and fat contents (FC) and genotypes across families using anova and transmission disequilibrium test (TDT). In within-family analysis, one family showed a significant effect for FC. These results could indicate linkage disequilibrium between the FABP3 gene and a quantitative trait loci (QTL) for FC, with the heterozygous genotype associated with a positive effect in this trait.

Characterization, genetic variation and chromosomal assignment to sheep chromosome 2 of the ovine heart fatty acid-binding protein gene (FABP3)

The purpose of this study was to locate and detect genetic variation in the sheep FABP3 gene, a candidate gene for milk and meat quality traits in sheep. We have obtained an almost complete sequence (4,689 bp, excluding a part of intron 1) of the sheep FABP3 gene using PCR-based comparative genome walking. Sheep FABP3 has been located to chromosome 2 by sheep sequence-specific PCR on DNA from a sheep/rodent cell hybrid panel, and confirmed by linkage mapping using the International Mapping Flock. Direct sequencing of PCR products amplified from different DNA samples of Manchega breed sheep over the complete sheep FABP3 gene revealed 13 SNPs, one CTC insertion/deletion and a variable polyA tract. This poly A tract was found in association with a SINE/artiodactyls repeat. In addition, two SNPs were screened in different sheep breeds.

Selection response for growth in a Spanish Merino flock

Weight and growth data on 5,136 lambs, from 104 sires and 1,552 dams were collected during 5 yr (13 lambing seasons) of selection for high weaning weight in a single flock under range conditions. Ewes were culled based on fertility and replaced by ewe lambs selected for high weaning weight. Heritabilities of birth weight, weaning weight (30 d), preweaning daily gain, postweaning daily gain, and weight at 90 d, respectively, were .13, .09, .03, .15, and .11. Genetic correlations were generally high. Genetic and phenotypic improvements of weaning weight were 22 +/- 3.0 and 198 +/- 11.3 g per lambing season, respectively, with three lambing seasons per year. At the end of the experiment, phenotypic mean weaning weight was 2.4 kg higher than the initial values. Estimated and theoretical responses were similar in the sire population. At the 13th lambing season, average breeding value of 30-d weight of the ram population was 600 g higher than the mean initial breeding value in the base population. Projected average breeding value of the lamb population under random mating at the 23rd lambing season was equal to 404 g.