Pregnancy rates in lactating Holstein-Friesian cows after artificial insemination with sexed sperm.
Journal - Reproduction in domestic animals = Zuchthygiene (Germany )
The effects of artificial insemination (AI) using sexed sperm on pregnancy rates have seldom been studied in lactating dairy cows on commercial dairy farms. We evaluated pregnancy results after AI of 306 lactating dairy cows, of which 157 were inseminated with 2x10(6) frozen/thawed sexed sperm and 149 with 15x10(6) frozen/thawed unsexed sperm. The average pregnancy and calving rates were 21.0% and 20% for the sexed-sperm AIs and 46% and 45% for the unseparated control-sperm AIs respectively (p<0.001). The proportion of female calves derived from sexed-sperm AI was 82% compared with 49% for control AI (p<0.01). The proportion of live and healthy calves in single births was 100% for sexed-sperm AI and 97% for control AI (p>0.05). Our results indicate that AI with low-dose sexed sperm under field conditions in commercial dairy herds without oestrus synchronization results in significantly reduced pregnancy rates compared with normal-dose AI. Improved insemination strategies combined with increased sperm doses are needed before the use of sexed sperm can be of any significant benefit for the dairy and beef industry.
|ISSN : ||0936-6768|
|Mesh Heading : ||Animals Cattle Dairying Estrus Synchronization Female Insemination, Artificial Lactation Male Pregnancy Pregnancy Outcome Sperm Count Spermatozoa methods physiology veterinary physiology|
|Mesh Heading Relevant : ||Pregnancy Rate Sex Determination (Genetics) physiology veterinary veterinary|
Effect of insemination with doses of 2 or 15 million frozen-thawed spermatozoa and semen deposition site on pregnancy rate in dairy cows.
Journal - Theriogenology (United States )
The effects of low-dose artificial insemination (AI) on pregnancy rates have seldom been studied in lactating dairy cows. We evaluated the pregnancy results after AI with doses of 2 and 15 million frozen-thawed spermatozoa and the effect of semen deposition in lactating dairy cows. A total of 284 first inseminations with 2 million spermatozoa and 312 first inseminations with 15 million spermatozoa were performed on 480 dairy farms. Low-dose inseminations (2 million spermatozoa) under field conditions in commercial dairy herds, without estrus synchronization, generally resulted in significantly reduced pregnancy rates compared with normal doses (15 million spermatozoa). The bull x technician effect on fertility was statistically significant. This finding indicates that there is a high variability in fertility among bulls using 2 million spermatozoa per dose. The semen deposition site did not influence pregnancy rates. It is concluded that a dose of 2 million frozen-thawed spermatozoa is probably too low for most bulls to achieve acceptable pregnancy rates in dairy cows.
|ISSN : ||0093-691X|
|Mesh Heading : ||Animals Cattle Cryopreservation Estrus Synchronization Female Hot Temperature Insemination, Artificial Male Pregnancy Semen Preservation Spermatozoa methods veterinary|
|Mesh Heading Relevant : ||Sperm Count physiology veterinary veterinary physiology|
Fertility of frozen-thawed stallion semen cannot be predicted by the currently used laboratory methods
Journal - Acta Veterinaria Scandinavica
The aim of the project was to use current simple and practical laboratory tests and compare results with the foaling rates of mares inseminated with commercially produced frozen semen. In Exp. 1, semen was tested from 27 and in Exp. 2 from 23 stallions; 19 stallions participated in both experiments. The mean number of mares per stallion in both experiments was 37 (min. 7, max. 121). Sperm morphology was assessed and bacterial culture performed once per stallion. In Exp. 1, progressive motility after 0, 1, 2, 3, and 4 h of incubation using light microscopy, motility characteristics measured with an automatic sperm analyzer, plasma membrane integrity using carboxyfluorescein diacetate/propidium iodide (CFDA/PI) staining and light microscopy, plasma membrane integrity using PI staining and a fluorometer, plasma membrane integrity using a resazurin reduction test, and sperm concentration were evaluated. In Exp. 2, the same tests as in Exp. 1 and a hypo-osmotic swelling test (HOST) using both light microscopy and a fluorometer were performed immediately after thawing and after a 3-h incubation. Statistical analysis was done separately to all stallions and to those having = 20 mares; in addition, stallions with foaling rates < 60 or = 60% were compared. In Exp. 1, progressive motility for all stallions after a 2 – 4-h incubation correlated with the foaling rate (correlation coefficients 0.39 – 0.51), (p < 0.05). In stallions with > 20 mares, the artificial insemination dose showed a correlation coefficient of -0.58 (p < 0.05). In Exp. 2, the HOST immediately after thawing showed a negative correlation with foaling rate (p < 0.05). No single test was consistently reliable for predicting the fertilizing capacity of semen, since the 2 experiments yielded conflicting results, although the same stallions sometimes participated in both. This shows the difficulty of frozen semen quality control in commercially produced stallion semen, and on the other hand, the difficulty of conducting fertility trials in horses.
An intronic insertion in KPL2 results in aberrant splicing and causes the immotile short-tail sperm defect in the pig
Journal - PNAS
The immotile short-tail sperm defect is an autosomal recessivedisease within the Finnish Yorkshire pig population. This diseasespecifically affects the axoneme structure of sperm flagella,whereas cilia in other tissues appear unaffected. Recently,the disease locus was mapped to a 3-cM region on porcine chromosome16. To facilitate identification of candidate genes, we constructeda porcine-human comparative map, which anchored the diseaselocus to a region on human chromosome 5p13.2 containing eightannotated genes. Sequence analysis of a candidate gene KPL2revealed the presence of an inserted retrotransposon withinan intron. The insertion affects splicing of the KPL2 transcriptin two ways; it either causes skipping of the upstream exon,or causes the inclusion of an intronic sequence as well as partof the insertion in the transcript. Both changes alter the readingframe leading to premature termination of translation. Furtherwork revealed that the aberrantly spliced exon is expressedpredominantly in testicular tissue, which explains the tissue-specificityof the immotile short-tail sperm defect. These findings showthat the KPL2 gene is important for correct axoneme developmentand provide insight into abnormal sperm development and infertilitydisorders.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Data deposition: The sequences reported in this paper have beendeposited in the GenBank database (accession nos. DQ119847 forthe Sus scrofa KPL2 mRNA sequence and DQ092447 for the Sus scrofaKPL2 partial genomic sequence).© 2006 by The National Academy of Sciences of the USA
|Keywords : ||cilia • retrotransposon • spermatogenesis|