R.G. Warner

Bio: R.G. Warner is an academic researcher from Cornell University. The author has contributed to research in topics: Rumen & Amino acid. The author has an hindex of 19, co-authored 47 publications receiving 1287 citations. Previous affiliations of R.G. Warner include Ithaca College & United States Department of Agriculture.

Relationship of Various Blood Metabolites to Voluntary Feed Intake in Lactating Ewes

Abstract: Two-day trials were conducted with ewes in early lactation. A pelleted ration (45% conc-55% roughage) was fed for a period of three hours at 8 AM and 3:30 PM. On day 1 sufficient feed was offered to insure ad libitum consumption at both periods. On day 2 the AMfeed was limited to one-half the amount consumed dur ing the pre-experimental AMperiod, and the PM feed was ad libitum. Carotid and jugu lar blood samples were taken at 0, 0.5, 1.5, 3 and 7 hours after the AMmeal. Correlations were calculated between AMand PM feeding periods on days 1 and 2. Interval feed con sumption was measured after 0.5, 1.5 and 3 hours in the AMand 0.5 and 3 hours in the PM. Seventy percent of the feed was consumed in the first 20 to 30 minutes. Blood vola tile fatty acids (VFA) and ketones increased markedly and peaked at 3 hours (day 1) and 1.5 hours (day 2). Blood glucose levels dropped sharply by 0.5 hour but increased significantly by 1.5 hours on both days. Plasma free fatty acids (FFA) decreased on both days, but rose markedly on day 2 by 7 hours. Acetate, propionate and glucose levels were poorly correlated to feed intake patterns. Ketone correlations, although low, had a pattern similar to butyrate correlations. Butyrate and FFA levels were the most highly correlated to subsequent VFI. FFA concentration at 7 hours was the best single predictor of subsequent feed intake, accounting for 50% of the variation (fi2 = 0.496).

Energy contributions of volatile fatty acids from the gastrointestinal tract in various species

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)

Postingestive Feedback as an Elementary Determinant of Food Preference and Intake in Ruminants

Abstract: Ruminants select nutritious diets from a diverse array of plant species that vary in kinds and concentrations of nutrients and toxins, and meet their nutritional requirements that vary with age, physiological state. and environmental conditions. Thus, ruminants possess a degree of nutritional wisdom in the sense that they generally select foods that meet nutritional needs and avoid foods that cause toxicosis. There is little reason to believe that nutritional wisdom occurs because animals can directly taste or smell either nutrients or toxins in foods. Instead, there is increasing evidence that neurally mediated interactions between the senses (i.e., taste and smell) and the viscera enable ruminants to sense the consequences of food ingestion, and these interactions operate in subtle but profound ways to affect food selection and intake, as well as the hedonic value of food. The sensation of being satisfied to the full (i.e., satiety) occurs when animals ingest adequate kinds and amounts of nutritious foods, and animals acquire preferences (mild to strong) for foods that cause satiety. Unpleasant feelings of physical discomfort (i.e., malaise) are caused by excesses of nutrients and toxins and by nutrient deficits, and animals acquire aversions (mild to strong) to foods that cause malaise. What constitutes excesses and deficits depends on each animal's morphology, physiology, and nutritional requirements. This does not mean that ruminants must maximize (optimize) intake of any particular nutrient or mix of nutrients within each meal or even on a daily basis, given that they can withstand departures from the normal average intake of nutrients (i.e., energy-rich substances, nitrogen, various minerals, and vitamins). Rather, hemostatic regulation needs only some increasing tendency, as a result of a gradually worsening deficit of some nutrient or of an excess of toxins or nutrients, to generate behavior to correct the disorder. Extreme states should cause herbivores to increase diet breadth and to acquire preferences for foods that rectify maladies. From an evolutionary standpoint, mechanisms that enable animals to experience feedback, sensations such as satiety and malaise, should be highly correlated with nutritional well being, toxicosis, and nutritional deficiencies, which are directly related with survival and reproduction.

Voluntary food intake and diet selection in farm animals.

Abstract: Feeding behaviour feedback signals ruminant gastrointestinal tract metabolites and hormones central nervous control integrative theories of food intake control growth and fattening reproduction and lactation diet digestability and concentration of available energy specific nutrients affecting intake learning about food - preferences diet selection appetites for specific nutrients environmental factors affecting intake the intake of fresh and conserved grass prediction of voluntary intake. Appendices: particular features of poultry and ruminant animals outline programme to identify and store meals from the identities of animals and weights of food containers.

Antioxidative and growth-promoting effect of selenium on senescing lettuce

Abstract: In human and animal cells, Se plays an essential role in antioxidation and exerts an antiaging function but it is toxic at high dietary intake. To increase its intake in forage and foodstuffs, Se fertilization is adopted in some countries where soils are low in bioavailable Se, even though higher plants are regarded not to require Se. To test its ability to counteract senescence-related oxidative stress in higher plants, a pot experiment was carried out with lettuce (Lactuca sativa) cultivated with increasing amounts of H2SeO4. The yields harvested 7 or 14 weeks after sowing revealed that a low Se dosage (0.1 mg kg−1 soil) stimulated the growth of senescing seedlings (dry weight yield by 14%) despite a decreased chlorophyll concentration. The growth-promoting function was related to diminished lipid peroxidation. In young and senescing plants, the antioxidative effect of Se was associated with the increased activity of glutathione peroxidase (GSH-Px). In the senescing plants, the added Se strengthened the antioxidative capacity also by preventing the reduction of tocopherol concentration and by enhancing superoxide dismutase (SOD) activity. When no Se was added, tocopherols and SOD activity diminished during plant senescence. The higher Se dosage (1.0 mg kg−1 soil) was toxic and reduced the yield of young plants. In the senescing plants, it diminished the dry weight yield but not the fresh weight yield.