Magister Scientiae - MSc (Biodiversity and Conservation Biology / Beach-cast kelp (the most widely used feed for commercially grown South African abalone) is plentiful during winter months when periodic storms cause kelp to wash ashore. During summer, however, this resource is not always readily available and farmed abalone are often starved for short periods. The aim of this research was to assess how periodic kelp starvation influences growth of the commercially grown abalone, Haliotis midae Linnaeus. / South Africa

Please read the abstract in the section 00front of this document / Thesis (PhD Agric (Animal Science))--University of Pretoria, 2006. / Animal and Wildlife Sciences / unrestricted

An investigation was carried out into the effects of some dietary factors on the serum cholesterol and serum total lipid levels in both normal and hyperthyroid chicks. Dietary factors investigated were the effects of two levels of protein, two levels of fat, and two levels of vitamins. Basal diets were fed at either a 20% or 26% protein level and when dietary fat was investigated the dextrose of the basal diet was substituted for a hydrogenated vegetable oil to make up 12% of the diet. The vitamin supplement in the high vitamin diets fed consisted of additional amounts of the following B complex vitamins: choline chloride, calcium panthothenate, folacin, niacin and riboflavin. Chicks were rendered hyperthyroid by feeding diets containing 0.02% iodinated casein. Hypothyroidism was induced by the feeding of 0.1% thiouracil. Normal chicks showed lower levels of serum cholesterol and serum total lipids when they were fed basal diets consisting of 26% protein level than when fed basal diets consisting of a 20% protein level. Normal chicks fed high fat diets showed higher levels of serum cholesterol and serum total lipids than normal chicks fed low fat diets. Normal chicks fed diets low in the B complex vitamins showed higher levels of serum cholesterol than normal chicks fed diets high in the B complex vitamins. The growth rate of chicks rendered hyperthyroid varied. In many instances hyperthyroid chicks grew at a significantly faster rate than normal chicks while in some instances no differences were noted. In some cases chicks rendered hyperthyroid showed depressed growth rates. No clear explanation could be given for such an effect on the growth rate of hyperthryoid chicks. It seems reasonable, however, to suspect that seasonal changes may affect thyroid activity and consequently the growth rate of the chicks in question. No differences were noted between the serum cholesterol and serum lipid levels from hyperthryoid chicks fed the basal diets containing 20%, and 26% protein. Hyperthyroid chicks, however, showed lower levels of serum cholesterol than normal chicks when the diet fed was low in the B complex vitamins, calcium panthothenate, choline chloride, folacin, niacin and riboflavin. The effect on the serum cholesterol and serum total lipids when the chicks were rendered hyperthyroid varied. The results suggest some interaction between thyroid state and diet on the serum cholesterol and serum total lipids. / Land and Food Systems, Faculty of / Graduate

A series of experiments were conducted to investigate the need by poultry for unidentified factors for maximum growth, egg production, fertility, hatchability and viability. Dehydrated cereal grass and dehydrated alfalfa were fed as supplements to a practical poultry diet. Data collected included body weights, feed consumption, egg production, fertility, hatchability and viability. The experiments were continued through three generations of birds in order to study any long term effects. In order to Investigate the possibility that bacterial synthesis provided a source of unidentified factors In the litter one additional group of adult birds was fed a basal diet and maintained on deep litter while another receiving the same diet was maintained on a raised wire floor. It was found that neither 2.5 nor 5 percent of either dehydrated cereal grass or dehydrated alfalfa had any effect on growth, maintenance of body weight, efficiency of feed utilization, egg production, fertility or hatchability. The presence of dehydrated green feed in the diet reduced the incidence of mortality in chicks during the period from 4 to 12 weeks of age. This effect was noted only when the chicks were under stress due to severe infection with coccidiosis. The dehydrated green feeds had no effect on the incidence of mortality during the first 4 weeks of age, the late growing stage, or the period of egg production. These results indicated that under normal conditions the Ingredients of the basal diet provided adequate amounts of the unidentified factor(s) present in dehydrated green feed. In addition, bacteria synthesis in the litter appeared to provide a source of an unidentified factor necessary for high hatchability. Another series of experiments were conducted in which chicks maintained in battery brooders were fed purified diets supplemented with dehydrated cereal grass, dehydrated alfalfa and forage juice. Various other supplements were added to the diet separately and in combination with the green feed supplements in. an attempt to determine the nature of the unidentified growth factor(s) present in green feeds. The additional supplements included herring meal, penicillin, lactose, the ash of dehydrated cereal grass and the ash of forage juice. In order to study the effect of maternal diet on the response of chicks to unidentified factors, the chicks used were from parent stock variously depleted of the unidentified factors. It was found that dehydrated cereal grass, dehydrated alfalfa and forage juice contain an unidentified factor required by chicks for rapid early growth. This factor differed from the factor present in herring meal. The response to either of these factors was dependent on the presence of the other in the diet. Both dehydrated cereal grass and forage juice, however, appeared to contain small quantities of the herring meal factor. The unidentified growth factor present in dehydrated cereal grass was shown to be carried over from the dam to the chick. The variability in growth rate of the chicks obtained from hens fed the control diet suggested that bacterial synthesis in the litter provided a source of the unidentified factor present in dehydrated green feed. The amount of the factor thus available to the hens varied as conditions were more or less favourable for bacterial growth. The nature of the factor(s) present in the green feed supplements is not clear. A growth response to the ash of dehydrated cereal grass and of forage juice was obtained as well as to the intact supplements. The balance among the various inorganic constituents of the diet may be involved rather than a single mineral. The fact, that a greater growth response was obtained from supplements which increased the acidity In the intestinal tract suggests that these supplements may act Indirectly by affecting the absorption of nutrients. / Land and Food Systems, Faculty of / Graduate

Four groups of weanling Hereford heifers were placed on four different winter planes of nutrition for a period of two years according to the following pattern: Group I - Low plane of nutrition Group II - Medium-low plane of nutrition Group III - Medium-high plane of nutrition Group IV - High plane of nutrition During the summer seasons the heifers were kept on pasture providing the same feeding level for all animals. The one year old heifers were bred during the months of June and July. All animals were weighed weekly and feed consumption was recorded weekly. To illustrate the growth rate of the heifers, K-values were calculated for all animals by the method of least squares and their growth curves were constructed. At the end of the second winter period all parturition data were carefully recorded and the rate of growth of the calves studied. From the results obtained in this experiment the following conclusions can be drawn: (1) The first post-weaning winter period is very important in regard to the feeding level of young growing heifers. The medium-low plane of nutrition (Group II) showed the best results from the economic point of view. (2) Young heifers can be bred as yearlings if the previous winter-feeding level allows them to grow continuously and to reach at least 700 pounds body weight before the breeding period starts. (3) The gestation period did not result in a decreased growth rate of the bred heifers. (4) The physical difficulties of parturition in two year old heifers do not appear to be insurmountable if the winter plane of nutrition is adequate. (5) The lactation period means a heavy drain on the young female hence a high level of nutrition must be provided in terms of sufficient amount of pasture dry matter during the grazing season. (6) Average birth weight of calves was 62.9 pounds, being higher for bull calves than heifer calves. (7) Pasture dry matter requirements for beef cattle may be calculated from the following equation: DM = 0.17 w•⁷ (w is animal weight given in pounds) / Land and Food Systems, Faculty of / Graduate

Five experiments in series, requiring a total of 3,000 chicks, were conducted to test modifications of and supplements to the Connecticut broiler ration. Wheat and/or No. 1 recleaned ground feed screenings were tested to replace the corn of the original ration. Soybean oil meal and / or fishmeal alone or in combination with meatmeal were tested as sources of supplementary protein. Furthermore, two crude fermentation antibiotic preparations, arsonic acid and B-complex vitamins were tested as supplements to the Connecticut broiler ration. Good quality feed wheat can replace the corn content of the Connecticut broiler ration on a pound per pound basis. The excess protein in a modified Connecticut broiler ration in which the corn was replaced with wheat cannot be reduced by lowering the level of supplementary protein without slowing the growth rate of chicks. No. 1 recleaned ground feed screenings when incorporated into the Connecticut broiler ration as the sole grain did not promote as great a growth response in chicks as a combination of wheat and corn. The efficiency of feed utilization was lower with the feed screenings ration than with the ration with corn and wheat. However, when No. 1 recleaned ground feed screenings replaced one-half of a grain mixture in a chick starting ration the chicks grew at the same rate as the chicks receiving the ration in which no replacement was made. The mixture of meatmeal, fishmeal and soybean oil meal of the Connecticut broiler ration was superior in promoting faster chick growth than was a ration containing either fishmeal or soybean oil meal as sole sources of supplementary protein. A combination of fishmeal and soybean oil meal as a source of supplementary protein was superior to either protein supplement alone in promoting the early growth of chicks. The fishmeal, when included as the sole source of supplementary protein, promoted the most efficient utilization of feed, though such a ration did not produce maximum growth. All the modified Connecticut broiler rations, when supplemented with crude commercial antibiotic preparation gave an increased growth rate in chicks. The extent to which the antibiotic supplement increased the growth rate depended on the basal ration used. In all instances antibiotic supplemented rations were more efficiently utilized than were the unsupplemented control rations. The addition of arsonic acid promoted a greater growth response in chicks fed this supplemented ration than the unsupplemented control rations. This increased growth rate of chicks receiving the arsonic acid persisted to seven and one-half weeks. The addition of B-complex vitamins to the Connecticut broiler ration promoted a growth response in chicks equal to the growth response of chicks receiving an antibiotic supplemented Connecticut ration. The extent to which the mixture of vitamins increased the growth rate depended on the basal ration used. / Land and Food Systems, Faculty of / Graduate

A study has been made on the growth stimulatory-effect of antibiotics when fed to chicks as supplements to different rations. A total of 9 biological tests employing 1280 chicks were carried out. Chicks fed the Connecticut ration and modifications thereof showed a significant growth response to aureomycin supplementation of the rations. The efficiency of feed utilization was improved by the addition of aureomycin to the rations in this experiment. The effect of aureomyoin has been tested in rations in which the protein level has been adjusted to 16%, 17.9%, 19.5% and 22% respectively. The basal rations used consisted of ground corn and wheat as the cereal grain and soybean oil meal and fishmeal as the protein supplements along with additional vitamins and minerals to balance the ration. The results showed that aureomycin did not lower the dietary requirement of the chick for protein. A test was made on the effect of antibiotics on growth of chicks when fed in rations which were deficient in specific amino acids. A wheat ration deficient in lysine and a corn ration deficient in tryptophan have been used. The results showed that antibiotics did not lower the dietary requirement of the chick for either lysine or tryptophan. Antibiotics were fed in chick rations containing different amounts of available carbohydrates. It was found that antibiotics did not lower the dietary requirement of the chick for carbohydrate. A comparison of aureomycin and penicillin showed no difference in growth stimulating properties between the two antibiotics under the conditions of the different experiments. Aureomyoin supplement (aurofac) promoted the same growth response at 0.05 and 1.0% levels. The greatest growth response to antibiotics was obtained when the chicks were fed a diet adequate in available carbohydrates and protein and balanced in amino acids. / Land and Food Systems, Faculty of / Graduate

This thesis is the study of the literature pertinent to the assessment of growth in addition to the analysis of growth data obtained from the Albino Rat, Yorkshire Swine, Black-Tail Deer and a group, of ten Hereford Bulls. It has been concluded that animals grow at a constant percentage rate relative to body weight over each distinct portion of their growth curve. A significant error in the expression of rate of gain is introduced if animals growth rate is calculated over any but an instantaneous period. The latter is possible because growth of an animal body is directly proportional to the protoplasmic mass, a first order reaction and as such is exponential and when the expression is integrated, the slope of the' regression line, logarithm of body weight on time is provided over the period when relative growth rate is constant. From the results of ration variations with male Wistar rats it was concluded that upon returning to ad libitum feeding they will grow at the same relative rate as their controls despite thirty per cent reduction below ad libitum intake over periods up to two thirds of the birth to sexual maturity phase. The extrapolation is made that beef bull calves proceeding from varying environments normally, experienced on pure-breeding establishments will not provide biased data when placed on a test ration and allowed a period for the rumen microflora to become adjusted to the new ration. / Land and Food Systems, Faculty of / Graduate

(a) The Availability of Lysine Autoclaved in the Presence of a Carbohydrate. Heat treatment has long been known to improve the value of soybean oilmeal for chick growth. However, more recently it has been demonstrated that too much heat or too long a heating period lowers the availability of certain of the amino acids present. This lowered availability was accompanied by a brown coloration. Investigators had shown that such a brown coloration occurs in other materials as a result of a reaction between reducing sugars and amino acids. As a result this study was undertaken to determine whether a similar reaction was responsible for the darkening in colour of the soybean during heating and whether or not such a reaction affected the nutritive value of the meal. The results of the study showed that a decrease in nutritive value did accompany the browning of soybean oilmeal. It was also shown that this decrease was mainly due to a lowering of the available methionine. As the lysine gave the greatest growth response, the study was continued using crystalline lysine and cerelose. It was shown the reaction was affected by the time of heating, the ratio of lysine to carbohydrate present, and the presence of water. Assays were carried out both biologically and micro-biologically. (b) The Animal Protein Factor in Relation to the Nutrition of the Chick. A series of three experiments were carried out to determine, if possible, the value of Animal Protein Factor Concentrates in proactical chick rations when fed to chicks which were not depleted of the factor(s). Experiment I was set up using a basal ration which would correspond to a practical starter ration using wheat and a mixture of coarse grains as the cereals. The ration was fed with and without a source of animal protein and was supplemented at various levels with the A.P.F. produced by-Merck and Company. Experiment II was set up using a high energy type of diet containing corn and soybean such as is used for broiler production. Males and females were fed separately to determine if there was a separate response of cockerels and pullets to the A.P.F. Supplementation. Experiment III was set up again using a corn soybean ration. The purpose of this experiment was to compare the Animal Protein Factor Concentrates produced by Merck and Lederle respectively. From the results it appears that supplementation with A.P.F. concentrates is practical but that the results vary with the level and the type of diet used. Apparently there is an optimum level above which further supplementation exerts a depressing effect upon chick growth. This is also true where fishmeal is included in the diet. Lederle gave a greater response than did the Merck product both in growth and feed efficiency. / Land and Food Systems, Faculty of / Graduate

In Study I alfalfa-bermuda grass hay or oat straw was fed with rolled barley, pelleted beet pulp, soybean oil meal and cracked wheat, in various proportions, in twenty protein-supplemented rations to immature Hereford steers. A control ration of 10% long straw, 78% rolled barley and 12% soybean oil meal was included. The best results were obtained with a roughage level of 10%. However, it was shown that it was feasible to feed roughage levels as high as 40% without detrimental effects to either average daily gain, feed efficiency, or carcass quality. In Study II various feed grains were fed in the ratio 90:10 (concentrate to roughage). The Canadian feed grains of barley and wheat were compared with corn. Various ratios of these feed grains were also compared. Excellent gains and feed efficiencies were obtained on all rations and it was shown that the cost of the grains available would be the largest factor in determining which to use. / Land and Food Systems, Faculty of / Graduate