Interrelationships between energy balance and postpartum reproductive function in dairy cattle.

Pregnancy, decreased feed intake during late gestation, lactogenesis, and parturition have dramatic effects on metabolism in dairy cows during the transition period from 3 wk before calving to 3 wk after calving. Increases in plasma NEFA occur during the 10 d before calving and may precede the decrease in feed intake. Plasma NEFA concentrations are highest at calving and decrease rapidly after calving. Plasma glucose concentration decreases during the transition period except for a transient increase associated with calving. Hepatic glycogen is reduced and lipid is increased during the transition period. Feed intake is usually decreased 30 to 35% during the final 3 wk prepartum, but negative energy and protein balances are not as severe as during the week following parturition. Prepartum feed intake is positively correlated to postpartum feed intake; therefore, efforts to maximize feed intake should begin before calving. Overconditioned cows may be more susceptible to a prepartum decrease in feed intake. Increasing nutrient density of the diet during the transition period may enhance feed intake. Feeding more fermentable carbohydrate during the prepartum transition period may acclimate the microbial population to lactation diets, promote development of ruminal papillae, increase absorptive capacity of the rumen epithelium, and reduce lipolysis by delivering more glucogenic precursor to the liver and enhancing blood insulin. Supplementing fat to transition diets does not seem to alleviate health problems associated with negative energy balance. Enhancing amino acid absorption by the prepartum cow may improve lactation performance and health, although mechanisms of action have not been identified.

https://webpages.uidaho.edu/ruminant_nutrition/reading materials 511/nutrient metabolism/nutrinet metabolism- grummer 1995.pdf

Impact of changes in organic nutrient metabolism on feeding the transition dairy cow.

Chemical factors involved in ruminal fiber digestion.

Etiology of Lipid-Related Metabolic Disorders in Periparturient Dairy Cows

There has been great interest in dry matter intake regulation in lactating dairy cattle to enhance performance and improve animal health and welfare. Predicting voluntary dry matter intake (VDMI) is complex and influenced by numerous factors relating to the diet, management, housing, environment and the animal. The objective of this review is to identify and discuss important metabolic factors involved in the regulation of VDMI and their integration with metabolism. We have described the adaptations of intake and metabolism and discussed mechanisms of intake regulation. Furthermore we have reviewed selected metabolic signals involved in intake regulation. A substantial dip in VDMI is initiated in late pregnancy and continues into early lactation. This dip has traditionally been interpreted as caused by physical constraints, but this role is most likely overemphasized. The dip in intake coincides with changes in reproductive status, fat mass, and metabolic changes in support of lactation, and we have described metabolic signals that may play an equally important role in intake regulation. These signals include nutrients, metabolites, reproductive hormones, stress hormones, leptin, insulin, gut peptides, cytokines, and neuropeptides such as neuropeptide Y, galanin, and corticotrophin-releasing factor. The involvement of these signals in the periparturient dip in intake is discussed, and evidence supporting the integration of the regulation of intake and metabolism is presented. Still, much research is needed to clarify the complex regulation of VDMI in lactating

C.E. Coppock

Papers

Effect of forage-concentrate ratio in complete feeds fed ad libitum on feed intake prepartum and the occurrence of abomasal displacement in dairy cows

Effect of forage-concentrate ratio in complete feeds fed ad libitum on energy intake in relation to requirements by dairy cows.

Effect of Group versus Individual Feeding of Complete Rations on Feed Intake of Lactating Cows

Computer Summaries of Life Cycle Data for Cow Research Herds