| 1. |
- Bezerra Lima Verde, Isabel, et al.
(författare)
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Sperm Quality in Young Bull Semen Can Be Improved by Single Layer Centrifugation
- 2022
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Ingår i: Animals. - : MDPI AG. - 2076-2615. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary Genomic selection enables bulls with desirable genes to be identified early in life. Livestock producers need to use the semen from young bulls as early as possible for efficient milk and meat production with fewer greenhouse gas emissions. However, semen from young bulls is often of lower quality than needed for freezing for commercial artificial insemination. Colloid centrifugation selects spermatozoa with the desirable characteristics needed for fertilization from the rest of the ejaculate. In this study, split ejaculates from young bulls were prepared with or without colloid centrifugation. Using this technique, sperm doses of acceptable quality for artificial insemination could be produced from ejaculates that would otherwise be discarded. Thus, the semen from young bulls would be usable for artificial insemination sooner than is currently the case. Interest in using semen from young bulls is increasing due to identifying promising animals by genomic selection. However, sperm quality in these ejaculates may not reach currently accepted standards for the cattle breeding industry. The purpose of this study was to determine if centrifugation of semen from young bulls through the Bovicoll colloid could improve sperm quality sufficiently for the frozen semen to be acceptable for artificial insemination. Ejaculates from 19 young bulls were split and either processed by Single-Layer Centrifugation (SLC) or not (CON) before freezing. After thawing, sperm quality was evaluated by determination of membrane integrity, mitochondrial membrane potential, DNA integrity, production of reactive oxygen species, sperm morphology and motility. Approximately half of the CON samples reached acceptable post-thaw quality (membrane integrity >= 40%) despite being below the breeding company ' s desired sperm concentration threshold pre-freezing. In the remaining samples, sperm quality was improved by SLC such that 45% of them reached acceptable quality post-thaw. Almost 75% of the young bull sperm samples could have produced usable frozen semen doses by adjusting the breeding company ' s current processing protocols. Since lowering the generation interval has a direct effect on the genetic gain per year, SLC could aid genetic progress in cattle breeding.
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| 3. |
- Glantz, Maria, et al.
(författare)
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Effect of polymorphisms in the leptin, leptin receptor and acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) genes and genetic polymorphism of milk proteins on bovine milk composition.
- 2012
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Ingår i: Journal of Dairy Research. - 0022-0299. ; 79:1, s. 110-118
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Tidskriftsartikel (refereegranskat)abstract
- The relations between cow genetics and milk composition have gained a lot of attention during the past years, however, generally only a few compositional traits have been examined. The aim of this study was to determine if polymorphisms in the leptin (LEP), leptin receptor (LEPR) and acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) genes as well as genetic polymorphism of β-casein (β-CN), κ-CN and β-lactoglobulin (β-LG) impact several bovine milk composition traits. Individual milk samples from the Swedish Red and Swedish Holstein breeds were analyzed for components in the protein, lipid, carbohydrate and mineral profiles. Cow alleles were determined on the following SNP: A1457G, A252T, A59V and C963T on the LEP gene, T945M on the LEPR gene and Nt984+8(A-G) on the DGAT1 gene. Additionally, genetic variants of β-CN, κ-CN and β-LG were determined. For both the breeds, the same tendency of minor allele frequency was found for all SNPs and protein genes, except on LEPA1457G and LEPC963T. This study indicated significant (P<0·05) associations between the studied SNPs and several compositional parameters. Protein content was influenced by LEPA1457G (G>A) and LEPC963T (T>C), whereas total Ca, ionic Ca concentration and milk pH were affected by LEPA1457G, LEPA59V, LEPC963T and LEPRT945M. However, yields of milk, protein, CN, lactose, total Ca and P were mainly affected by β-CN (A2>A1) and κ-CN (A>B>E). β-LG was mainly associated with whey protein yield and ionic Ca concentration (A>B). Thus, this study shows possibilities of using these polymorphisms as markers within genetic selection programs to improve and adjust several compositional parameters.
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| 4. |
- Glantz, Maria, et al.
(författare)
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Genomic selection in relation to bovine milk composition and processability.
- 2012
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Ingår i: Journal of Dairy Research. - 0022-0299. ; 79:1, s. 53-59
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Tidskriftsartikel (refereegranskat)abstract
- Genomic selection is a new technology in which selection decisions are based on direct genomic values (DGVs) or genomic enhanced breeding values (GEBVs). The objective of this study was to evaluate the relations between DGVs and several milk traits important for both the nutritional value and processability of milk. This is a new approach and can be used to increase the knowledge on how genomic selection can be used in practice. Morning milk samples from Swedish Holstein cows were analyzed for milk composition and technological properties. DGVs were received for each cow for milk, protein and fat yield, milk index, udder health, Nordic total merit and a quota was calculated between fat and milk yield as well as protein and milk yield. The results show that linear correlations exist (P<0·10) between the studied DGVs and contents and yields of parameters in the protein (P=0·002-0·097), fat (P=0·024-0·055) and mineral profiles (P=0·001-0·099) as well as for cheese characteristics (P=0·004-0·065), thus making it possible to obtain detailed information on milk traits that are not registered in the milk recording scheme. Hence, genomic selection will be an efficient tool for breeding and dairy industry to select cows early in life for targeted milk production.
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| 5. |
- Hurri, Emma, et al.
(författare)
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Post-thaw semen quality in young bull ejaculates before being accepted for commercial semen doses
- 2022
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Ingår i: Veterinary Record. - : Wiley. - 0042-4900 .- 2042-7670. ; 191
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Tidskriftsartikel (refereegranskat)abstract
- Background: Genomic selection enables bulls with desirable characteristics to be identified at a young age, but sperm quality can be poor in the ejaculates of young bulls. Few studies have been done on post-thaw sperm quality in bulls less than 10 months old. The objective of this study was to determine the age at which post-thaw sperm quality was acceptable for artificial insemination.Methods: Semen was collected by artificial vagina; samples containing 100-500 million spermatozoa/ml were frozen for this study. Post-thaw analyses of membrane integrity (MI), mitochondrial membrane potential (MMP), chromatin integrity, morphology, production of reactive oxygen species and sperm kinematics were made.Results: The age at which ejaculates exceeded the breeding company's thresholds of acceptance varied considerably among individuals, with 285 days being the earliest. Morphology (p < 0.003), MI (p = 0.0096), high MMP (p = 0.043) and superoxide production (p = 0.0084) increased between the first and last ejaculates but reached acceptable levels at different ages for individual bulls.Conclusions: It was possible to obtain acceptable post-thaw sperm quality from samples even though sperm concentration was lower than the breeding company's threshold. Therefore, it might be feasible to use ejaculates earlier than is currently considered possible, by modifying semen handling protocols.
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| 6. |
- Königsson, Fredrik, 1983-, et al.
(författare)
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Characterization and Potential of Dual FuelCombustion in a Modern Diesel Engine
- 2011
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Ingår i: SAE Technical Paper 2011-01-2223. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
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Konferensbidrag (refereegranskat)abstract
- Diesel Dual Fuel, DDF, is a concept which promises the possibility to utilize CNG/biogas in a compression ignition engine maintaining a high compression ratio, made possible by the high knock resistance of methane, and the resulting benefits in thermal efficiency associated with Diesel combustion.A series of tests has been carried out on a single cylinder lab engine, equipped with a modern common rail injection system supplying the diesel fuel and two gas injectors, placed in the intake runners. One feature of port injected Dual Fuel is that full diesel functionality is maintained, which is of great importance when bringing the dual fuel technology to market. The objective of the study was to characterize and investigate the potential for dual fuel combustion utilizing all degrees of freedom available in a modern diesel engine.Increased diesel pilot proved efficient at reducing NOx emissions at low λ. Advanced combustion phasing has the potential to extend the lean limit for operation. Stoichiometric operation using high levels of EGR is identified as a promising field in conjunction with raised inlet temperature.
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| 7. |
- Königsson, Fredrik, 1983-, et al.
(författare)
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Combustion Modes in a Diesel-CNG Dual Fuel Engine
- 2011
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Ingår i: SAE Technical Paper 2011-01-1962, 2011. - 400 Commonwealth Drive, Warrendale, PA, United States : Society of Automotive Engineers of Japan, Inc. ; , s. 2387-2398
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Konferensbidrag (refereegranskat)abstract
- Diesel Dual Fuel, DDF, is a concept where a combination of methane and diesel is used in a compression ignited engine, maintaining the high compression ratio of a diesel engine with the resulting benefits in thermal efficiency.One benefit of having two fuels on board the vehicle is the additional degree of freedom provided by the ratio between the fuels. This additional degree of freedom enables control of combustion phasing for combustion modes such as Homogenous Charge Compression Ignition, HCCI, and Partly Premixed Compression Ignition, PPCI. These unconventional combustion modes have great potential to limit emissions at light load while maintaining the low pumping losses of the base diesel engine.A series of tests has been carried out on a single cylinder lab engine, equipped with a modern common rail injection system supplying the diesel fuel and two gas injectors, placed in the intake runners. Four load points are investigated and three different types of combustion are evaluated.The study confirmed the desirable emission characteristics of HCCI and PPCI combustion and demonstrated the potential to control the combustion phasing by utilizing all degrees of freedom provided by a common rail injection system and two fuels.
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| 8. |
- Königsson, Fredrik, 1983-, et al.
(författare)
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Controlling the Injector Tip Temperature in a DieselDual Fuel Engine
- 2012
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Ingår i: SAE Technical Paper Series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Diesel Dual Fuel, DDF, is a concept where a combination of methane and diesel is used in a compression ignited engine, maintaining the high compression ratio of a diesel engine with the resulting benefits in thermal efficiency. Attention has recently been drawn to the fact that the tip of the diesel injector may reach intolerable temperatures. The high injector tip temperatures in the DDF engine are caused by the reduction in diesel flow through the injector. For dual fuel operation, as opposed to diesel, high load does not necessarily imply a high flow of diesel through the injector nozzle.This research investigated the factors causing high injector tip temperatures in a DDF engine and the underlying mechanisms which transfer heat to and from the injector tip. Parameter sweeps of each influential parameter were carried out and evaluated. In addition to this, a simple and useful model was constructed based on the heat balance of the injector tip.Decreasing the thermal resistance between the injector tip and the cooling water by inserting a copper sleeve around the injector tip has the potential to greatly reduce the injector tip temperature and effectively remove it as a limiting factor.
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| 9. |
- Nilsson, Kajsa, et al.
(författare)
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Characterisation of non-coagulating milk and effects of milk composition and physical properties on rennet-induced coagulation in Swedish Red Dairy Cattle
- 2019
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946 .- 1879-0143. ; 95, s. 50-57
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Tidskriftsartikel (refereegranskat)abstract
- Non-coagulating milk is a serious problem in the cheese industry, since it decreases cheese yield, resulting in decreased economic output. This study evaluated rennet-induced coagulation properties and composition of milk from individual Swedish Red Dairy Cattle. Milk samples from 679 individual cows were rheologically evaluated, of which 18.1% of the cows produced non-coagulating milk and 18.9% produced poor-coagulating milk. This resulted in 37% of the milk samples being non-optimal in cheese production, which is an alarmingly high figure. A comparison between non-coagulating and coagulating milk showed a significantly lower calcium content and less free Ca 2+ in non-coagulating milk. The results provide more information about non- and poor-coagulating milk and will be further used to understand the genetic background of non-coagulating milk and breed against this undesired milk property.
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| 10. |
- Stålhammar, Marcus, et al.
(författare)
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Electromagnetic response of topological superconductors
- 2021
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Ingår i: Physical Review B. - 2469-9950 .- 2469-9969. ; 103:23
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Tidskriftsartikel (refereegranskat)abstract
- We resolve several puzzles related to the electromagnetic response of topological superconductors in 3+1 dimensions. In particular we show by an analytical calculation that the interface between a topological and normal superconductor does not exhibit any quantum Hall effect as long as time reversal invariance is preserved. We contrast this with the analogous case of a topological insulator to normal insulator interface. The difference is that in the topological insulator the electromagnetic vector potential couples to a vector current in a theory with a Dirac mass, while in the superconductor a pair of Weyl fermions is gapped by Majorana masses and the electromagnetic vector potential couples to its axial currents.
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