In metabolism Mg plays an important role because it affects many cellular enzymes in the body. The energy metabolism and protein synthesis are dependent on Mg as an enzyme activator, Mg is also involved in the synthesis of RNA and DNA. Absorption of Mg primarily takes place over the ruminal epithelium in ruminants. The main storage of Mg is in the bones but that can only be reached if the cow is in great need of calcium or phosphorus, it's a hormonal regulated process that induces catabolism of bones. Free and available sources of Mg are found in soft tissues and in the extra cellular fluids that includes cerebrospinal fluids and blood.

Feed intake in dairy cows is regulated by a variety of factors influencing hunger and satiety. One of the regulation systems includes the short chain fatty acids produced during feed degradation in the rumen. Starch can be digested either in the rumen where short chain fatty acids are produced or in the small intestine where glucose is the end product. Since glucose does not have the same effect on satiety that short chain fatty acids have, the site of starch digestion might be an important factor that affects feed intake and milk production. The aim of this study was to investigate the effects of site of starch digestion on feeding behaviour (feed intake, consumption time, and eating frequency) and milk production. Because feeding behaviour is closely connected to the cows? environment, the study also included observations of behaviour. Three different feed rations were compared.

AbstractAn approaching overproduction of cereals and a future uncertain supply of non genetic modified vegetable protein feedstuffs have increased the interest in an expansion of the domestic production of protein feedstuffs in Norway. Besides rapeseed (Brassica campestris), peas (Pisum sativum) may be the most suitable crop for this purpose. Peas are characterized by having a relatively high content of crude protein, ranging between 20-26%, a high content of starch, 42-51%, and a low content of fat. In general, the energy value for peas is higher than for barley but lower than for rapeseed and soybean meal.Pea protein consists of albumins and globulins to 85-100%, which leads to the fact that a large part of the pea protein is soluble and degradable in the rumen. Starch in peas is on the other hand to a large extent resistant to rumen degradation compared to starch from other starch rich feedstuffs.

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 transform grass to milk with help from ruminal microorganisms that can digest indigestible fiber in their feed. The digestive system of the cow is adapted to a diet consisting of forage and disorders like acidosis, laminitis and abomasal displacement can occur if the feed contains too much starch. To achieve the highest production possible the cow has to be given a high amount of concentrate or grain as the difference in milk yield is significant, approximately 1000 kg energy corrected milk per cow and year between conventional and organic cows that are fed a lower versus a higher share of forage. If the cow shall be able to eat the same amount of energy from forage as from grain or concentrate the eating- and rumination time gets longer and she might not be able to eat enough, which will result in a lower milk yield and will make it harder for the cow to recover from the negative energy balance that originate from the beginning of the lactation. Fat and in a sense protein content differs also depending on if the cow is given a high or low share of forage..

I takt med ökande mjölkproduktion hos dagens mjölkkor ökar också energibehovet vilket ställer stora krav på utfodringen. En stor andel kraftfoder i foderstaten kan ge upphov till en pH-sänkning i vommen och subakut vomacidos (SARA) kan uppkomma. Syftet med den här litteraturstudien var att ge en översikt över vad SARA är, vilka orsakerna är, vilka följder det kan få med särskilt fokus på fång, samt hur man kan förebygga utvecklingen av SARA. Vid utfodring med en hög andel kraftfoder bildas stora mängder flyktiga fettsyror, VFA, som kan ge upphov till en pH-sänkning om bildandet av VFA överstiger absorptionen från vommen, och SARA kan därigenom uppkomma. Vid utfodring med en högre andel kraftfoder anpassas vommens slemhinna och blir större och får därmed en större absorptiv förmåga. Vid ett snabbt byte går denna anpassning dock inte alltid tillräckligt snabbt vilket kan ge upphov till att pH sänks. Även vommens mikroflora förändras vid utfodring med en större andel kraftfoder. I samband med SARA kan olika kliniska symptom ses.