Glucose Metabolism and Milk Yield of Cows Infused Abomasally or Ruminally with Starch

Abstract

The effect of ruminal or abomasal starch infusion on milk yield and glucose metabolism of early lactation cows was measured. Four cows were continuously infused in the rumen or abomasum with partially hydrolyzed starch (1500 g/d) or were not infused (control) for three 14-d periods during wk 4 to 12 postpartum. Milk yield averaged over 40 kg/d throughout the experiment. Milk and milk lactose yields tended to increase when starch was infused and DMI was decreased, regardless of the site of infusion. Starch infusion increased mean insulin concentration and tended to decrease the concentration of serum nonesterified fatty acids. Ruminal starch infusion did not affect glucose irreversible loss rate but tended to increase glucagon concentration and decrease glucose oxidation. The increased milk yield that occurred when starch was infused ruminally relative to the milk yield of control cows could be a result of increased microbial protein supply or increased energy availability. Compared with ruminal starch infusion, abomasal starch infusion tended to increase the irreversible loss rate of glucose and to increase glucose oxidation. Abomasal infusion tended to increase plasma insulin concentration and to decrease the nonesterified fatty acid concentration relative to ruminal infusion. Infusion of starch abomasally resulted in increases of most uses of glucose, including milk lactose production, glucose oxidation, and the possible storage of glucose as body fat, which indicates that the early lactation dairy cow has a greater capacity for glucose metabolism than is provided by voluntary feed intake of average diets, but that not all available glucose is partitioned to the mammary gland. These data should be useful in testing current concepts and equations in nutritional and metabolic models of dairy cattle.

Effect of dietary energy source on energy balance, production, metabolic disorders and reproduction in lactating dairy cattle

“…Concerning plasma NEFA levels, 13 [9, [60][61][62][63][64][65][66][67][68] out of 15 studies found an increase after feeding extra lipogenic nutrients. In contrast to studies where extra glycogenic nutrients were fed, 13 [60,61,66,[68][69][70][71][72][73] out of 14 reported studies found a decrease in plasma NEFA levels. Plasma BHBA levels increased after feeding extra lipogenic nutrients in five out of eight studies [68,69,74,75].…”

“…Plasma BHBA levels increased after feeding extra lipogenic nutrients in five out of eight studies [68,69,74,75]. Extra glycogenic nutrients were related to a decrease in plasma BHBA levels in eight out of nine reported studies [61,69,70,72,74,76]. Plasma glucose (10 out of 13 studies) and insulin (6 out of 9 studies) concentrations were decreased after feeding extra lipogenic nutrients and in almost all cases increased after feeding extra glycogenic nutrients (glucose 13 out of 14 studies; insulin 7 out of 8 studies) [8, 9, 60, 61, 64, 66-68, 70-72, 74, 76, 77].…”

“…Plasma GH concentration was increased in most studies (4 out of 6 studies) after feeding extra lipogenic nutrients [8,9,61,64]. In contrast to a decrease after feeding extra glycogenic nutrients in 5 out of 6 studies [61,70,71].…”

“…Two studies found a positive effect of feeding extra glycogenic nutrients on liver glycogen content [70,72], as a representative of stored carbohydrates.…”

“…Abomasal starch infusion tended to decrease plasma NEFA levels more than ruminal infusion. This is probably caused by the production of the VFA propionate, butyrate and acetate from ruminally infused starch, while infused abomasal starch is intestinally digested and absorbed as glucose [70].…”