Comparison of fertility results after vaginal insemination using different thawing procedures and packages for frozen ram semen

<p>Abstract</p> <p>Background</p> <p>The effect of different thawing procedures for ram semen frozen in minitubes and mini straws on the fertility of sheep was tested in a field trial.</p> <p>Methods</p> <p>Altogether, 719 Norwegian Crossbred ewes, aged between six months and six-and-a-half years from 8 farms, were inseminated vaginally in natural oestrus with frozen-thawed semen. Minitubes were thawed at 70°C for 8 sec (T70) and mini straws either at 50°C for 9 sec (S50) or at 35°C for 12 sec (S35).</p> <p>Results</p> <p>Vaginal insemination with 200 × 10⁶spermatozoa resulted in 25-days non-return rates of 63.2, 59.6, and 62.5% (overall 61.8%), respectively, and lambing rates of 56.8, 55.0, and 59.2% (overall 57.0%), respectively. No significant effect on fertility (as 25-days non-return- or lambing rate) was seen for straw type/thawing temperature (P = 0.5/0.5), but semen filled in mini straws and thawed at 35°C resulted numerically in the highest lambing rate (59.2%). A significant effect was, however, seen for farmer (P = >0.0001/>0.0001) and ram (P = 0.009/0.002). Moreover, age of the ewes had a significant effect on the NR rate (0.007), but not on lambing rate (P = 0.2).</p> <p>Conclusion</p> <p>A vaginal deposition of frozen ram semen containing approximately 200 × 10⁶spermatozoa, filled in mini straws and thawed at 35°C is a simplified technique that under field conditions and used on a do-it-yourself regime gives acceptable lambing rates in Norway.</p

Allele Interaction – Single Locus Genetics Meets Regulatory Biology

Background: Since the dawn of genetics, additive and dominant gene action in diploids have been defined by comparison of heterozygote and homozygote phenotypes. However, these definitions provide little insight into the underlying intralocus allelic functional dependency and thus cannot serve directly as a mediator between genetics theory and regulatory biology, a link that is sorely needed. Methodology/Principal Findings: We provide such a link by distinguishing between positive, negative and zero allele interaction at the genotype level. First, these distinctions disclose that a biallelic locus can display 18 qualitatively different allele interaction sign motifs (triplets of +, – and 0). Second, we show that for a single locus, Mendelian dominance is not related to heterozygote allele interaction alone, but is actually a function of the degrees of allele interaction in all the three genotypes. Third, we demonstrate how the allele interaction in each genotype is directly quantifiable in gene regulatory models, and that there is a unique, one-to-one correspondence between the sign of autoregulatory feedback loops and the sign of the allele interactions. Conclusion/Significance: The concept of allele interaction refines single locus genetics substantially, and it provides a direct link between classical models of gene action and gene regulatory biology. Together with available empirical data, our results indicate that allele interaction can be exploited experimentally to identify and explain intricate intra- and inter-locu

Casein SNP in Norwegian goats: additive and dominance effects on milk composition and quality

<p>Abstract</p> <p>Background</p> <p>The four casein proteins in goat milk are encoded by four closely linked casein loci (<it>CSN1S1</it>, <it>CSN2</it>, <it>CSN1S2 </it>and <it>CSN3</it>) within 250 kb on caprine chromosome 6. A deletion in exon 12 of <it>CSN1S1</it>, so far reported only in Norwegian goats, has been found at high frequency (0.73). Such a high frequency is difficult to explain because the national breeding goal selects against the variant's effect.</p> <p>Methods</p> <p>In this study, 575 goats were genotyped for 38 Single Nucleotide Polymorphisms (SNP) located within the four casein genes. Milk production records of these goats were obtained from the Norwegian Dairy Goat Control. Test-day mixed models with additive and dominance fixed effects of single SNP were fitted in a model including polygenic effects.</p> <p>Results</p> <p>Significant additive effects of single SNP within <it>CSN1S1 </it>and <it>CSN3 </it>were found for fat % and protein %, milk yield and milk taste. The allele with the deletion showed additive and dominance effects on protein % and fat %, and overdominance effects on milk quantity (kg) and lactose %. At its current frequency, the observed dominance (overdominance) effects of the deletion allele reduced its substitution effect (and additive genetic variance available for selection) in the population substantially.</p> <p>Conclusions</p> <p>The selection pressure of conventional breeding on the allele with the deletion is limited due to the observed dominance (overdominance) effects. Inclusion of molecular information in the national breeding scheme will reduce the frequency of this deletion in the population.</p

Genetic parameters of blood β-hydroxybutyrate predicted from milk infrared spectra and clinical ketosis, and their associations with milk production traits in Norwegian Red cows

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An attempt at predicting blood beta-hydroxybutyrate from Fourier-transform mid-infrared spectra of milk using multivariate mixed models in Polish dairy cattle

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Prediction accuracy of direct and indirect approaches, and their relationships with prediction ability of calibration models

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Use of simulation to examine a dairy goat breeding program in Tanzania

This paper discusses selection in a dairy goat population for improved performance by conceptualizing it for a population in Tanzania. Seven strategies (5, 10, 20, 30, 50, 70, 100 test bucks) were simulated. A progeny test based selection breeding program fitting Mgeta (Morogoro, Tanzania) situation was optimized. The selection intensity, accuracy of prediction, and genetic gain of milk yield (kg) per day at heritability 0.1 and 0.2 are discussed. Use of natural mating for 1000 goats, in cooperating villages, were assumed. Three elite bucks were selected for breeding with 12% of the best females. Outlines of essential elements for a local sustainable dairy goat breeding program in Tanzania are included with a schematic figure showing selection steps for dairy goat breeding scheme fitting in Mgeta area. This study found that selection intensity gained when testing many bucks is more important for daily milk yield (DMY) (kg) genetic gain than the extra accuracy gained when testing fewer bucks. Mgeta has a mountainous terrain, small herd sizes per farmer and long distance from one cooperating village to another. Testing 30 bucks is practical for Mgeta. That gives relatively high (42% or 53%) accuracy of selection and genetic gain (2% or 2.6% for 0.1 or 0.2 heritability). The current results of estimated genetic gain are close to reported findings under other environments. Based on dairy goats of Norwegian breed in Tanzania, milked once daily, if 210 days of milking and an average of 1 litre milk yield is considered, the possible genetic gain per year in this program is equivalent to an increase of 4.2kg for 0.1 heritability and 5.5kg of milk per doe for 0.2 heritability of the trait. Such an increase in amount of milk due to a breeding program under the considered environment is promising. Collaborative efforts from farmers to consumers along the dairy goat market chain remain important elements to realize a sustainable high gain. The proposed breeding program may not be perfect in future because of practical options and accessibility to new knowledge. Thus, it becomes indispensable to revise breeding programs.publishedVersio