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H.N. Harrison

Bio: H.N. Harrison is an academic researcher from Cornell University. The author has contributed to research in topics: Dairy cattle & Rumen. The author has an hindex of 4, co-authored 5 publications receiving 382 citations.
Topics: Dairy cattle, Rumen, Hay, Reticulum, Abomasum

Papers
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Journal ArticleDOI
TL;DR: In this article, 12 young dairy calves equipped with rumen cannulae were fed milk and housed in tie stalls with elevated floors to prevent bedding consumption, to study their effect on rumen mucosal development.

284 citations

Journal ArticleDOI
TL;DR: A stasis in omasal tissue growth occurred, and the abomasum continued to grow at the same rate as body size, and Mucosal and muscular growth were independent.

115 citations

Journal ArticleDOI
H.N. Harrison1, R.G. Warner1, E.G. Sander1, J.K. Loosli1, S. T. Slack1, K.L. Turk1 
TL;DR: The experiments were conducted during a fall and summer season with calves housed in four calf units, consisting of pens and tie stalls, with calves consuming 350 lb.

4 citations


Cited by
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Journal ArticleDOI
E. N. Bergman1
TL;DR: The VFA, also known as short-chain fatty acids, are produced in the gastrointestinal tract by microbial fermentation of carbohydrates and endogenous substrates, such as mucus and may indirectly influence cholesterol synthesis and even help regulate insulin or glucagon secretion.
Abstract: The VFA, also known as short-chain fatty acids, are produced in the gastrointestinal tract by microbial fermentation of carbohydrates and endogenous substrates, such as mucus. This can be of great advantage to the animal, since no digestive enzymes exist for breaking down cellulose or other complex carbohydrates. The VFA are produced in the largest amounts in herbivorous animal species and especially in the forestomach of ruminants. The VFA, however, also are produced in the lower digestive tract of humans and all animal species, and intestinal fermentation resembles that occurring in the rumen. The principal VFA in either the rumen or large intestine are acetate, propionate, and butyrate and are produced in a ratio varying from approximately 75:15:10 to 40:40:20. Absorption of VFA at their site of production is rapid, and large quantities are metabolized by the ruminal or large intestinal epithelium before reaching the portal blood. Most of the butyrate is converted to ketone bodies or CO2 by the epithelial cells, and nearly all of the remainder is removed by the liver. Propionate is similarly removed by the liver but is largely converted to glucose. Although species differences exist, acetate is used principally by peripheral tissues, especially fat and muscle. Considerable energy is obtained from VFA in herbivorous species, and far more research has been conducted on ruminants than on other species. Significant VFA, however, are now known to be produced in omnivorous species, such as pigs and humans. Current estimates are that VFA contribute approximately 70% to the caloric requirements of ruminants, such as sheep and cattle, approximately 10% for humans, and approximately 20-30% for several other omnivorous or herbivorous animals. The amount of fiber in the diet undoubtedly affects the amount of VFA produced, and thus the contribution of VFA to the energy needs of the body could become considerably greater as the dietary fiber increases. Pigs and some species of monkey most closely resemble humans, and current research should be directed toward examining the fermentation processes and VFA metabolism in those species. In addition to the energetic or nutritional contributions of VFA to the body, the VFA may indirectly influence cholesterol synthesis and even help regulate insulin or glucagon secretion. In addition, VFA production and absorption have a very significant effect on epithelial cell growth, blood flow, and the normal secretory and absorptive functions of the large intestine, cecum, and rumen. The absorption of VFA and sodium, for example, seem to be interdependent, and release of bicarbonate usually occurs during VFA absorption.(ABSTRACT TRUNCATED AT 400 WORDS)

2,188 citations

Journal ArticleDOI
TL;DR: Understanding the factors affecting intestinal development will improve weaning strategies and foster better postweanling calf growth performance, as well as enhance the rate of herd genetic improvement.

486 citations

Journal ArticleDOI
TL;DR: It is concluded that milk-fed dairy calves can safely ingest milk at approximately 20% of body weight (BW/d), and greater milk consumption supports greater BW gain, improved feed efficiency, reduced incidence of disease, and greater opportunity to express natural behaviors, which in combination suggest improved welfare.

378 citations

Journal ArticleDOI
TL;DR: Feeding hay and starter in addition to milk resulted in forestomach development which included papillary and muscular growth of the reticulo-rumen and pigment deposition in the rumen mucosa, Histological observations suggest that the origin of this pigment probably is the Rumen contents in animals fed hay and grain.

375 citations

Journal ArticleDOI
TL;DR: Short chain fatty acids also named volatile fatty acids, mainly acetate, propionate and butyrate, are the major end-products of the microbial digestion of carbohydrates in the alimentary canal and are an important energy source for the gut mucosa itself.
Abstract: Short chain fatty acids (SCFA) also named volatile fatty acids, mainly acetate, propionate and butyrate, are the major end-products of the microbial digestion of carbohydrates in the alimentary canal. The highest concentrations are observed in the forestomach of the ruminants and in the large intestine (caecum and colon) of all the mammals. Butyrate and caproate released by action of gastric lipase on bovine milk triacylglycerols ingested by preruminants or infants are of nutritional importance too. Both squamous stratified mucosa of rumen and columnar simple epithelium of intestine absorb readily SCFA. The mechanisms of SCFA absorption are incompletely known. Passive diffusion of the unionized form across the cell membrane is currently admitted. In the lumen, the necessary protonation of SCFA anions could come first from the hydration of CO2. The ubiquitous cell membrane process of Na+-H+ exchange can also supply luminal protons. Evidence for an acid microclimate (pH = 5.8-6.8) suitable for SCFA-protonation on the surface of the intestinal lining has been provided recently. This microclimate would be generated by an epithelial secretion of H+ ions and would be protected by the mucus coating from the variable pH of luminal contents. Part of the absorbed SCFA does not reach plasma because it is metabolized in the gastrointestinal wall. Acetate incorporation in mucosal higher lipids is well-known. However, the preponderant metabolic pathway for all the SCFA is catabolism to CO2 except in the rumen wall where about 80% of butyrate is converted to ketone bodies which afterwards flow into bloodstream. Thus, SCFA are an important energy source for the gut mucosa itself.

351 citations