Production and metabolic effects of site of starch digestion in dairy cattle

摘要: Milk solids yield in modern dairy cows has increased linearly over the last 50 years, stressing need for maximal dietary energy intake to allow genetic potential milk be realized with minimal negative effects on health and reproduction. Feeding supplemental starch is a common approach increasing density of ration supplying carbon meeting substantial glucose requirement higher yielding cow. In this regard, it long held belief that feeding forms increase digestion small intestine absorption will benefit cow terms energetic efficiency production response, but data supporting dogma are equivocal. This review consider impact site metabolic responses lactating cows, including feed intake, composition, nutrient partitioning, capacity digestion, metabolism by splanchnic tissues (the portal-drained viscera liver). Whilst there appears considerable cow, numerous strategic studies implementing postruminal or infusions have observed increases yield, decreased fat concentration such little effect even early lactation. Measurements balance confirm majority arising from used high support body adipose protein retention, These may mediated changes insulin status, beneficial reproductive success well-being. However, shifting rumen impacts nitrogen economy as well microbial gained potentially absorbable endogenous faecal loss.