Publisher Summary This chapter describes the general aspects of the regulation of protein metabolism by diet and by hormones. There is a complex interrelationship between the diet and homeostatic mechanisms within the body. The chapter presents an integrated picture of dietary and hormonal factors that influence the course of protein metabolism in different organs. It also presents the evidence for the existence and nature of labile protein components of the body. Certain tissues protein increase or diminish rapidly in response to variations in dietary protein intake and could, thus, function as sensitive regulators in protein metabolism. Dietary factors other than protein intake can influence the protein content of tissues, and the next section, therefore, describes the influence exerted by dietary carbohydrate and fat on the course of protein metabolism and particularly on labile tissue proteins. The chapter also discusses the modifying action of hormones on protein distribution within the body, and the interaction between diet and hormones in this process.

General Aspects of the Regulation of Protein Metabolism by Diet and by Hormones

Nutrient requirements of all livestock are based on the size of the animal, how active the animal is, the body growth rate, and/or the animal’s level of milk production and fat content in milk produced. Maintenance requirements are for low levels of activity as when being fed in a dry lot situation. When animals are on pasture activity increases and these the requirements may be as much as 25% higher due to this increased activity.

Nutrient Requirements of Sheep

Rumen microbes and digestion of plant cell walls

Heat production of fasting white-tailed deer (Odocoilus virginianus) was measured over all months of the year. The deer were maintained in outdoor enclosures, they voluntarily restricted their feed intake and activity in winter, and experienced weight changes typical of wild deer. FMR followed a cyclic pattern. Average FMR of adults in summer coat from May through August (52.2 kcal/kg/24 hrs) was 1.5 times as high as that of deer in winter coat from September through April (33.8 kcal/kg/ 24 hrs). Results confirm the previously reported finding of lower metabolism in winter, and are in gen- eral conformance with reported changes in weight of thyroid glands, and certain activities of deer in an area of similar latitude in New York State. Date of measurement apparently had a stronger influence on FMR than either body size or sex. Values obtained were variable, and high compared to the accepted interspecies mean of 70 kcal/kg W?'7/24 hrs. Cyclic changes in metabolism in deer subject to normal weather conditions may represent a response to season and/or weather, and, in combination with other physiological and behavioral changes, form part of a complex adaptation for survival of deer living near the northern extremity of their range. Additional studies for determining total energy requirements are suggested. Abstract: Heat production of fasting white-tailed deer (Odocoilus virginianus) was measured over all months of the year. The deer were maintained in outdoor enclosures, they voluntarily restricted their feed intake and activity in winter, and experienced weight changes typical of wild deer. FMR followed a cyclic pattern. Average FMR of adults in summer coat from May through August (52.2 kcal/kg/24 hrs) was 1.5 times as high as that of deer in winter coat from September through April (33.8 kcal/kg/ 24 hrs). Results confirm the previously reported finding of lower metabolism in winter, and are in gen- eral conformance with reported changes in weight of thyroid glands, and certain activities of deer in an area of similar latitude in New York State. Date of measurement apparently had a stronger influence on FMR than either body size or sex. Values obtained were variable, and high compared to the accepted interspecies mean of 70 kcal/kg W?'7/24 hrs. Cyclic changes in metabolism in deer subject to normal weather conditions may represent a response to season and/or weather, and, in combination with other physiological and behavioral changes, form part of a complex adaptation for survival of deer living near the northern extremity of their range. Additional studies for determining total energy requirements are suggested.

Fasting metabolism of white-tailed deer1

Publisher Summary This chapter discusses the experiments done on male hamsters. It should be noted, however, that corresponding results have been obtained in females in nearly all cases, regardless of whether photoperiodic effects, the results after pineal manipulations or after application of melatonin are considered. Many mammalian species show a marked annual cycle of gonadal and other functions. In a number of cases it has been shown that the photoperiod, that is, the length of the daily light cycle and its changes, are involved in the regulation of this cycle. The pineal has been shown to participate in the transduction of photoperiodic effects of short photoperiods leading to regression and also of long photoperiods stimulating recrudescence. The latter effect is not only a suppression of antigonadotrophic effects from the pineal, but a positive stimulation. The exact role of melatonin in the photoperiodic mechanism and its site of action are still unclear. Strong effects of melatonin application have been found in photoperiodic mammals. Recent experiments suggest that not only the amount of melatonin, but its pattern of synthesis and release may be important in the conveyance of photoperiodic effects. No support for the assumption that the site of action of melatonin is the pineal itself has been found in experiments with pinealectomized animals.

Photoperiod, pineal, melatonin and reproduction in hamsters.

Value of Processed Poultry Waste as a Feed for Ruminants

Use of the Artificial Rumen Technique to Estimate the Nutritive Value of Forages

Responses of White-Tailed Bucks to Added Artificial Light

This investigation was conducted to determine the intracellular distribution of copper in the liver of normal sheep, and the changes associated with exposure to increased dietary copper. Normal rat liver (3.8 + 1.0) ~/g Cu/g liver, wet tissue basis) and normal sheep liver (102.0 -+ 37.2 /~g Cu/g liver) was processed to give the four common subcellular fractions. When the intracellular distribution of copper in the two species was compared, the cytosol fraction of sheep liver contained a much lower (P<.001) percentage of copper than normal rat liver. Although the debris fraction of sheep contained a higher (P<.001) percentage than the rat, this copper did not appear to be associated with any specific component of this fraction. Feeding a high level of dietary copper to sheep elevated hepatic copper concentration (238.5 -+ 84.2 /~g Cu/g liver) significantly (P<.05). Comparison with the normal group showed that with the higher liver copper concentration, proport ionally less (P<.05) of the copper was found in the large granule fraction while proport ional ly more (P<.05) was present in the cytosol. These changes in the intracellular copper distribution of copper-stressed sheep directly oppose what is known for copperstressed rats. (

T. A. Long

Papers

Value of Processed Poultry Waste as a Feed for Ruminants

Use of the Artificial Rumen Technique to Estimate the Nutritive Value of Forages

Responses of White-Tailed Bucks to Added Artificial Light

Intracellular distribution of hepatic copper in normal and copper-loaded sheep.

Intake and digestibility by sheep of rations containing various roughage substitutes.