Kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder
The purpose with this literature study was to investigate the possibilities for improvement of forage protein in dairy cows with focus on feeding strategies and conservation of forage protein. The utilization of forage protein in dairy cows is often not that efficient as it could be. The feed crude...
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| Formato: | L3 |
| Lenguaje: | sueco Inglés |
| Publicado: |
SLU/Dept. of Animal Nutrition and Management (until 231231)
2009
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| Materias: |
| _version_ | 1855572040760688640 |
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| author | Pettersson, Emma |
| author_browse | Pettersson, Emma |
| author_facet | Pettersson, Emma |
| author_sort | Pettersson, Emma |
| collection | Epsilon Archive for Student Projects |
| description | The purpose with this literature study was to investigate the possibilities for improvement of forage protein in dairy cows with focus on feeding strategies and conservation of forage protein. The utilization of forage protein in dairy cows is often not that efficient as it could be. The feed crude protein consists of both true proteins and non protein nitrogen. The digestion of proteins in the rumen depends on the protein degradation rate and the ability of the microbes to synthesize microbial protein. The microbes need a balance between carbohydrates that provide them with energy and proteins that are degradable in the rumen. Dairy cows that have large dietary needs for protein also require ruminal undegraded proteins, which are degradable in the small intestine. Microbial proteins and ruminal undegraded proteins are absorbed as amino acids in the small intestine. To supply the dairy cows' needs for protein by feeding with forage, the proteins in the forage has to be preserved after harvest. The protein content is affected by what crop is produced, the harvest system and the choice of conservation method. The protein breakdown, proteolysis, in forage begins after harvest and continues in the beginning of ensiling. This can be prevented by wilting, to slow down the reaction, or acid treatment for a fast pH drop. There are substances that can prevent proteolysis as well. Tannins that is present in birdsfoot trefoil and polyphenol oxidase in red clover. These prevent the protein from breakdown in silage and in rumen. The proteins become available in the small intestine, which is profitable for a ruminant. Studies with alfalfa hay and silage has shown that hay undergoes less proteolysis than silage, which means that more proteins are preserved in hay. Studies have also shown that proteins in red clover silage are more preserved than in alfalfa silage because less proteolysis occurs in red clover.
When the forage contains excessive amounts of non protein nitrogen and the energy source is insufficient, the microbes can't synthesize microbial proteins and the excess of nitrogen will be excreted as urea in the urine. If the nitrogen is not fixated by forage crops it will evaporate to the atmosphere as ammoniac which eventually contributes to nitrogen over-fertilizing when the rain falls down. The loss of proteins will increase the need for protein supplementation, which can be costly for the farmer. It is therefore of environmental and economical interest to decrease the nitrogen emission by improving the efficiency of utilization of forage proteins in dairy cows. |
| format | L3 |
| id | RepoSLU12314 |
| institution | Swedish University of Agricultural Sciences |
| language | swe Inglés |
| publishDate | 2009 |
| publishDateSort | 2009 |
| publisher | SLU/Dept. of Animal Nutrition and Management (until 231231) |
| publisherStr | SLU/Dept. of Animal Nutrition and Management (until 231231) |
| record_format | eprints |
| spelling | RepoSLU123142017-10-30T14:40:35Z Kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder How can utilization of forage protein become more efficient for dairy cows? Pettersson, Emma mjölkkor vall protein kväve kolhydrater proteolys ensilering hö tanniner polyfenoloxidaser The purpose with this literature study was to investigate the possibilities for improvement of forage protein in dairy cows with focus on feeding strategies and conservation of forage protein. The utilization of forage protein in dairy cows is often not that efficient as it could be. The feed crude protein consists of both true proteins and non protein nitrogen. The digestion of proteins in the rumen depends on the protein degradation rate and the ability of the microbes to synthesize microbial protein. The microbes need a balance between carbohydrates that provide them with energy and proteins that are degradable in the rumen. Dairy cows that have large dietary needs for protein also require ruminal undegraded proteins, which are degradable in the small intestine. Microbial proteins and ruminal undegraded proteins are absorbed as amino acids in the small intestine. To supply the dairy cows' needs for protein by feeding with forage, the proteins in the forage has to be preserved after harvest. The protein content is affected by what crop is produced, the harvest system and the choice of conservation method. The protein breakdown, proteolysis, in forage begins after harvest and continues in the beginning of ensiling. This can be prevented by wilting, to slow down the reaction, or acid treatment for a fast pH drop. There are substances that can prevent proteolysis as well. Tannins that is present in birdsfoot trefoil and polyphenol oxidase in red clover. These prevent the protein from breakdown in silage and in rumen. The proteins become available in the small intestine, which is profitable for a ruminant. Studies with alfalfa hay and silage has shown that hay undergoes less proteolysis than silage, which means that more proteins are preserved in hay. Studies have also shown that proteins in red clover silage are more preserved than in alfalfa silage because less proteolysis occurs in red clover. When the forage contains excessive amounts of non protein nitrogen and the energy source is insufficient, the microbes can't synthesize microbial proteins and the excess of nitrogen will be excreted as urea in the urine. If the nitrogen is not fixated by forage crops it will evaporate to the atmosphere as ammoniac which eventually contributes to nitrogen over-fertilizing when the rain falls down. The loss of proteins will increase the need for protein supplementation, which can be costly for the farmer. It is therefore of environmental and economical interest to decrease the nitrogen emission by improving the efficiency of utilization of forage proteins in dairy cows. Syftet med den här litteraturstudien var att undersöka möjligheterna till att förbättra mjölkkors utnyttjande av vallprotein och arbetet begränsades till utfodring och konservering av vall. Mjölkkors förmåga att utnyttja vallprotein är oftast inte så effektiv som den skulle kunna vara. Fodrets råprotein kan både vara äkta protein och icke-proteinkväve. Nedbrytningsgraden av proteiner i vommen beror på hur snabb nedbrytningshastighet proteinet har och på passagehastigheten ur vommen. Vommikroberna kan ta till vara mycket av det nedbrutna proteinet genom att tillverka mikrobprotein, men då krävs också en balans mellan tillgänglig energi från kolhydrater och proteiner i vommen. Mjölkkor som har stort proteinbehov behöver dessutom proteiner som passerar vommen, vomstabilt protein, och tas upp i tunntarmen, pga. att mikroproteiner inte räcker till. I tunntarmen tas både mikrobproteiner och vomstabila proteiner upp som aminosyror. För att mjölkkor ska kunna tillgodose sitt proteinbehov från vall krävs också att vallens proteiner bevaras efter skörd. Proteininnehållet påverkas bl.a. genom val av växtsort, skördeteknik och konserveringsmetod. Proteinnedbrytning, proteolys, i vallen börjar redan vid skörd och fortsätter vid ensilering men det kan förhindras genom bl.a. förtorkning och syrabehandling. Det finns ämnen som påverkar proteinets nedbrytningshastighet i ensilaget och i vommen. Till dessa hör tanniner, som bl.a. finns i käringtand och polyfenoloxidaser som finns i rödklöver. De binder till proteiner och gör dem otillgängliga för vommikroberna men proteinerna kan brytas ned i löpmagen och bli tillgängliga för absorption i tunntarmen, vilket är fördelaktigt för en idisslare. Studier har visat att proteiner i rödklöver bevaras bättre än proteiner i lusern då rödklöver genomgår mindre proteolys och mer äkta protein bevaras vilket utnyttjas bättre i vommen än icke-proteinkväve. Lusernhö har visats ge mindre proteolys än lusernensilage vilket innebär att proteiner bevaras bättre i hö. Icke-proteinkväve bryts snabbt ned till ammoniak i vommen och för att mikroorganismerna ska hinna med att tillverka mikrobprotein krävs det energi i form av lättillgängliga kolhydrater. När fodret innehåller ett överskott av icke-proteinkväve eller om energikällan inte är tillräcklig hinner mikroberna inte tillverka mikrobproteiner och överskottet av kväve kommer att utsöndras som urea via urin. Om kvävet inte fixeras av vallgrödan avdunstar det ut i atmosfären som ammoniak vilket senare kan bidra till kväveövergödning när det regnar ner. Förlusterna av proteiner ökar behovet av ett proteinfodermedel, vilket oftast är kostsamt för bonden. Av både miljömässiga och ekonomiska skäl är det därför av intresse att minska kväveutsöndringen genom att förbättra förutsättningarna för en mjölkko att tillgodose sig proteinet i vallfodret. SLU/Dept. of Animal Nutrition and Management (until 231231) 2009 L3 swe eng https://stud.epsilon.slu.se/12314/ |
| spellingShingle | mjölkkor vall protein kväve kolhydrater proteolys ensilering hö tanniner polyfenoloxidaser Pettersson, Emma Kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder |
| title | Kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder |
| title_full | Kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder |
| title_fullStr | Kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder |
| title_full_unstemmed | Kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder |
| title_short | Kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder |
| title_sort | kan mjölkkors utnyttjande av vallprotein bli bättre? : utfodringsstrategier och konserveringsmetoder |
| topic | mjölkkor vall protein kväve kolhydrater proteolys ensilering hö tanniner polyfenoloxidaser |