Author
S.A. Wolfe
Bio: S.A. Wolfe is an academic researcher from Purdue University. The author has contributed to research in topics: Energy balance. The author has an hindex of 2, co-authored 2 publications receiving 195 citations.
Topics: Energy balance
Papers
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TL;DR: The mean daily dry matter intake 28 days prepartum did not differ significantly and Digestible energy consumed during the 28 days before calving averaged 155, 138, 159, and 173% of National Research Council's maintenance requirements for the four treatment groups, respectively.
126 citations
TL;DR: Cows in the latter stages of lactation did not appear to regulate their intake according to physiological requirements for milk production, and cows in the groups fed higher concentrate feeds achieved energy balance earlier.
73 citations
Cited by
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TL;DR: Negative energy balance probably acts similarly to undernutrition and may manifest in delayed ovarian activity by impinging on pulsatile secretion of LH, and lower availability of glucose and insulin may also decrease LH pulsatility or limit ovarian responsiveness to gonadotropins.
1,140 citations
TL;DR: 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, and supplementing fat to transition diets does not seem to alleviate health problems associated with negative energy balance.
Abstract: 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.
905 citations
TL;DR: In this article, chemical constraints that may be responsible for the decrease in fiber digestion are explored, and a major factor appears to be rumen pH, to approximately 6.5 or 5.0, which results in depressed growth rates and decreased fibrolytic organisms.
802 citations
TL;DR: Research to determine methods to reduce fatty acid delivery to the liver or to enhance hepatic export of very low density lipoprotein near calving is warranted because of increased fatty acid uptake by the liver, fatty acid esterification, and triglyceride storage.
800 citations
01 Jan 2000
TL;DR: In this paper, the authors identified and discussed important metabolic factors involved in the regulation of dry matter intake in dairy cattle and their integration with metabolism, and discussed the adaptations of intake and metabolism and discussed mechanisms of intake regulation.
Abstract: 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
558 citations