Voluntary feed intake by dairy cattle

摘要: Feed intake is regulated and limited by the physical metabolic requirements of animals. Physical control voluntary dry matter (DMI) in high productivity dairy cows is, to a large extent, dependent on reticulo-rumen capacity/volume. fill thought be mainly determined rate digestion feed, passage effect diet. The neutral detergent fibre (NDF) water contents motility, volume, digestibility (NDFD) rumen are main factors controlling regulation. When energy or protein met then further stopped/depressed as result feedback via message from satiety centre within central nervous system. Volatile fatty acids (VFA) produced microbial degradation feed rumen. amount each acid absorbed has both an individual combined (as part mixture acids) regulation feed. Propionate most important all VFA since it enhances release insulin into blood which, stops Glucose other hand, little no role ruminants. Diets that highly fermentable produce instant titratable acidity these very strong inhibitory effects causing stasis cessation intake. Starch cereal grains normally added diets meet for milk yield. Rapid starch negative impact total tract fibre. availability depends type cereals intensity any processing they have undergone. Grass legume silage cut ensilaged at early maturity associated with increased NDF organic (OM) although reported such silages regulate metabolically rather than physically. However, chemical composition characteristics change plant matures. A number models been proposed predicting intake; their accuracies vary. Possible strategies improving utilization increasing include: shifting site small intestine through use processed (e. g. processing); selecting correct type; determining optimum level forages (grasses legumes).