One hundred and fifteen male weanling rats of the U.B.C. Wistar Strain were used to study the effect of changing energy level and protein:energy ratio of their ration on their growth rate, feed consumption, feed efficiency, body composition and metabolic rate. The rations used in this study were designed to test the hypothesis that the feed consumption of the rat is inversely proportional to the available energy content of its ration. Twenty semi-purified rations were formulated using sucrose, B. C. Herring Meal, hydrogenated vegetable oil, non-nutritive cellulose and vitamin and mineral premixes. The rations were calculated to contain 2000, 3000, 4000, 5000, or 5735 kilocalories of digestible energy per kilogram of dry matter and at each energy level to contain 30, 45, 60 or 75 milligrams of crude protein per kilocalorie of digestible energy. Most other nutrients (vitamins and minerals) were present in essentially constant amounts in each ration when levels were expressed as nutrient content per kilocalorie of apparent digestible energy. Ten of the rats were killed at a body weight of 65 grams for use as initial controls in the calculation of the composition of body weight gain. The remaining 105 animals were divided into twenty-one groups of five each. Each of twenty of the groups was assigned to an experimental ration and one group was fed a stock diet (U. B. C. Ration 10-61) as a secondary control. The animals were individually housed and were supplied with fresh bedding and water every third day. Their body weight and feed consumption were recorded daily. When an animal reached 58 grams body weight it was supplied with the previously assigned ration (prior to this time the animals were fed the above mentioned stock diet) and allowed to grow until it reached 165 grams body weight when it was killed and frozen for future chemical analysis. The experimental data used in the analysis of this study covered the body weight range of 65 to 165 grams body weight only. The apparent digestibility of the rations was determined using the chromic oxide technique. The energy content of the feed and feces was measured by bomb calorimetry and the apparent digestible energy content of the rations calculated. The protein and fat content of feed and feces was determined by Micro-Kjeldahl analysis and extraction with petroleum ether respectively and the apparent digestibility of these two ration components calculated. The proximate composition of the rats was determined on the individual animals with gastrointestinal contents included. The resting metabolic rate of a selected rat in each group was determined when the selected animal reached a body weight of 100, 130 and 165 grams. The resting metabolic rate of each of the initial control rats was determined just prior to the time it was killed. The experimental data indicate that the rat tends to eat to meet an energy requirement. The relationship between feed intake and apparent digestible energy is not in agreement with the initial hypothesis. An attempt to explain this deviation is presented and a general pattern of feed consumption relative to available energy is proposed which is believed to be applicable to all animals. Growth rates increased with increasing protein:energy ratios at fixed energy levels and increasing energy levels at fixed protein energy ratios. Feed efficiency increased with increasing energy level and with increasing protein: energy ratios. It is clearly shown that growth rate and feed efficiency, used alone, have limited usefulness in evaluating the performance of an animal. It is also clearly demonstrated that protein content of the ration when expressed as a percentage of the ration has no bearing on the performance that can be expected of an animal fed that ration. The body composition of the rats followed a pattern which is generally expected. The fat gain increased with increasing energy level at any given protein:energy ratio and increased with decreasing protein: energy ratios at any given energy level. The majority of the change in the fat content was balanced by differences which occurred in the protein and water content of the rats. The ash content was essentially constant in all groups. No apparent trends occurred in the resting metabolic rate measurements when considered on the basis of individual animals. Finally, it is suggested that the design of rations and the expression of feeding standards should be standardized and that the basis of this standard should be energy. In other words, rations and feeding standards should be expressed on a nutrient per available calorie basis rather than on a percentage basis. / Land and Food Systems, Faculty of / Graduate

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Several techniques were compared for the nutritive evaluation of grazed forage. It was shown that esophageal samples were more representative of the grazing animal's diet than clipped samples. High drying temperature affected the intake values obtained by different indicator methods. Results showed that the chromogen ratio and the lignin ratio methods could give relatively accurate and similar intake values provided the correct MEC combinations for chromogen and VanSoest's procedure for lignin were used. In vitro cellulose digestibility and animal behaviour studies suggested that the NVI computed using the lignin ratio method gave more meaningful results particularly for aftermath forages. In vivo and in vitro studies indicated that the first growth forage up to the midbloom stage was superior in feeding value to the best aftermath forage. As measured by the NVI the feeding value of pasture managed differently appeared to be affected more by stocking rate than by the method of grazing. [...]

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A possible nutritional role for certain of the naturally occurring α-glyceryl ethers has been investigated. Batyl, selachyl and chimyl alcohols have been administered per orum for extended periods to growing dogs and rats at various dosage levels to ascertain if these compounds produce inimical or favourable effects in terms of growth and haematopoietic responses. Groups of male and female dogs and rats maintained on normal rations were given daily doses of each of the three alcohols at a level of 6 mgs per kilogram of body weight for 180 days. There was no evidence to suggest that these compounds produced harmful effects. Histopathological study of the major tissue system confirmed this conclusion. A favourable response in the form of a slightly increased growth rate was noted in the female rats that received the selachyl alcohol. No evidence of a haematopoietic effect was obtained. In a second experiment, selachyl alcohol was offered as an addendum to a normal ration, to both dogs and rats at levels that ensured a daily consumption of 600 and 2400 mg per kilogram of body weight of this alcohol for a period of sixty days. Other groups of both species received batyl alcohol at the higher dosage level (2400 mg per kilogram of body weight) daily for the same time period. The results obtained suggest that both compounds when fed at the 2400 mg per kilogram level interfered with the digestibility of the ration offered and, in so doing, reduced the growth rate of the experimental dogs. A corresponding effect did not occur in the rats. Both alcohols, when administered at the highest dosage level, induced an increase in the reticulocyte count in the blood of the dogs and an increase in the percentage of nucleated red blood cells in the bone marrow smears prepared from the rats. A glyceryl ether-free synthetic ration supplemented with 0.5, 5 and 50 mg of batyl alcohol per kilogram of body weight was prepared and then offered to groups of young growing rats for a period of five weeks. No growth response was obtained at any level, suggesting that this compound does not have a nutritional function or that the rat is able to synthesize the compound at a rate that is adequate to permit near maximum growth. It is also possible that the animals had sufficient reserves of compounds of this type to permit growth at the measured rate. / Land and Food Systems, Faculty of / Graduate

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