Four experiments were carried out with laying hens to evaluate the effects of body weight, age, dietary protein, and tallow levels on performance, nutrient intake and energy utilization. In the first experiment, Single Comb White Leghorn birds were divided into four body weight groups at the onset of egg production. Voluntary feed intake was 18% less for the lightest (1.39 kg) in comparison with the heaviest group (1.83 kg). Egg weight was directly related to body weight with the heavy birds producing an average egg weighing 65.3 g and the lightest birds having an average egg weight of 58.9 g. Feed conversion was also significantly better for the lighter birds. Maintenance requirements for the heaviest and lightest birds were 60.5 and 57.9% of metabolizable energy consumed, respectively. Metabolizable energy intakes above maintenance were 131 kcal/d for the heavy birds and only 119 kcal for the light group. A composite regression analysis indicated a maintenance requirement of 127.7 kcal/d/kg('0(.)75) and an energetic efficiency of 75.2% for the conversion of metabolizable energy to net energy. In order to evaluate the effects of age and body weight on laying hen performance, the last three experiments were designed using old, molted, and young hens which were divided into the heaviest and lightest body weight groups. The old birds were 72 weeks old, the molted birds were 106 weeks old, and the young birds were 27 weeks old at the start of the studies. In each experiment the birds were fed ten experimental diets with 12, 14, 16, 18, and 20% dietary protein in combination of 1 and 4% supplemental fat. Egg output was increased with the supplementation of tallow in only the young birds; while energy retentions were improved in the old and molted birds with fat feeding. Average energy retentions per kg physiological body weight were 58.8, 41.7, and 38.6 kcal for the young, molted, and old hens, respectively. The light-bodied birds showed 9% better gross energetic efficiencies than the heavy-bodied birds. Estimated daily protein intake requirements were 16.8, 13.3, and 12.8 g/d to support production levels of 84, 64, and 66% for the young, old, and molted birds, respectively.

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Corrigenda inserted behind title page. / Copies of author's previously published articles inserted at end. / Includes bibliographical references (leaves 193-210). / xxii, 210 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates whether estrogen modulates the proteins associated with calcium transport (eg calcium binding protein, calbindin D28k) in the intestinal tissue during sexual maturation of laying hens. Studies the temporal and spatial expression of estrogen receptors (ER) and calcium binding protein in jejunal tissue. Findings indicated the potential of estrogen to induce calbindin D28K in the intestinal tissue, from which it can be concluded that estrogen may increase calcium absorption and consequently calcium retention. Shows that the amount of estrogen normally present in the reproductive system is sufficient for the normal capacity of egg and eggshell production. Egg production and shell quality are significantly reduced by phytoestrogen. It is recommended that the concentration of phytoestrogen in poultry diets be investigated in more detail as it may act as an anti-nutritive factor and affect metabolism and productivity. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 1999

The first three experiments of this thesis examined the effects of particle size reduction of grains in relation to feed form (mash vs. pellet), grain type (wheat vs. maize) and xylanase supplementation on broiler performance, energy utilisation, digestive tract development and digesta parameters. The fourth experiment examined the interaction between wheat hardness and xylanase supplementation. The effects of insoluble fibre source and whole wheat inclusion were studied in the fifth experiment. In the first experiment (Chapter 4), pelleting reduced nitrogen-corrected apparent metabolisable energy (AMEn), but broiler performance was superior in birds fed pelleted wheat-based diets compared to those fed mash diets. Feed form had a greater effect on various measured parameters than did particle size. Pelleting evened out differences in particle size distribution between treatments and, as a result, wheat particle size had no effect on the performance of broilers fed pelleted diets. In contrast, the second experiment (Chapter 5) showed that differences in particle size distribution persisted between diets after pelleting and, as a result, coarse grinding of wheat or maize improved broiler performance compared to those fed diets based on fine particles. These results may be related, in part, to changes in size distribution following pelleting. In mash diets, inconsistency in performance reponses were found. In the first experiment (Chapter 4), coarse grinding of wheat improved weight gain and feed per gain compared to medium grinding. In the third experiment (Chapter 6), however, grinding particle size had no influence on broiler performance. The observed discrepancy suggests involvement of other factors such as wheat cultivar and grain hardness. Data reported in Chapter 6 showed that xylanase supplementation improved feed per gain of birds fed the coarse particle size diet, but had no effect on those fed the medium particle size diet. In Chapter 7, there was a significant interaction between wheat hardness and xylanase supplementation due to the improved feed per gain and AMEn of birds maintained on hard wheat-based diet, while there was no effect of xylanase on sort wheat-based diet. These findings suggest that the efficiency of exogenous enzymes is influenced by both particle size and wheat hardness. Data reported in Chapter 7 showed that inclusion of soft or hard whole wheat pre-pelleting produced different particle size distributions in the pelleted diets. This suggested that hardness of the grain must be considered when choosing whole wheat for inclusion in broiler diets. Data on the effect of feed particle size on its subsequent distribution in poultry digesta are scanty. Results reported in Chapters 4 and 5 showed that there was no effect of feed particle size within feed form on duodenal digesta particle size. On the other hand, particle size of duodenal digesta was influenced by feed form (mash vs. pellet). Wheat hardness was also found to influence the particle size of proximal (duodenum and jejunum) intestinal digesta (Chapter 7). These results indicated that the gizzard does not uniformly reduce the size of all particles. However, the gizzard appears highly efficient in grinding large particles, although some large particles escape the grinding. The final experiment demonstrated that the effects of insoluble fibre on digestive tract development and broiler performance differed depending on the fibre source. Wood shavings, a source of coarse insoluble fibre, increased relative gizzard size and improved corrected feed per gain and ileal starch digestibility. In contrast, cellulose, a source of fine insoluble fibre, had no influence on these parameters. In conclusion, dietary manipulations, which stimulated gizzard development, positively influenced broiler performance and starch digestibility. The findings of this thesis suggest that energy savings during feed processing could be achieved by coarse grinding of grains with no adverse effect on broiler performance and that cereals used in broiler diets can be ground more coarsely than the current practice. Wheat hardness appears to be an important criterion to consider when choosing a cultivar for whole wheat inclusion in broiler diets. Another major finding was that the effectiveness of exogenous xylanase in wheat-based diets could be improved by considering factors such as particle size and wheat hardness.

Corn is widely used as animal feed as well as for fuel ethanol production. Fiber present in corn is not digested well by non-ruminants such as chicken and swine. Also, this fiber does not participate in conversion of starch to ethanol. Fiber separation from corn flour using the Elusieve process, a combination of sieving and air classification, would result in high starch animal feed and increase ethanol productivity. The objective of the first part of this dissertation was to understand the effect of retention screen size in the hammer mill on fiber separation from corn flour using the Elusieve process. Four different retention screen opening sizes were studied. The highest starch content of 65.2% was in the enhanced flour obtained by using 3.2 mm (8/64") retention screen; starch content of the original corn flour was 62.5%. The objective of the second part was to evaluate Elusieve process for sorghum flour. The combination of hammer milling and Elusieve process was less effective for sorghum flour compared to corn flour. The objectives of the third part were to determine the operating air velocities for corn particles and to compare physical properties of corn particles with that of Distillers’ dried grains with soluble (DDGS) particles. The operating air velocities for large, medium and small corn size fractions were 2.9 to 3.8, 2.8 to 3.0 and 2.5 to 2.6 m/s, respectively. Densities of nonfiber particles for corn flour were higher than for DDGS (earlier study). Compared to DDGS, the difference between fiber and nonfiber particle terminal velocities was higher for corn, signifying relative ease of operability for fiber separation from corn flour. The objective of the fourth part was to study the effect of corn moisture content on fiber separation. There was no effect of moisture content on fiber separation. The objective of the fifth part was to assess the economics of the Elusieve process. For ethanol plant of 50 million gallons/year capacity (50 MGY), payback period would be 3.1 years. The payback period for implementing Elusieve process in an integrated broiler operation with 8 million birds capacity would be 0.4 to 1.3 years.

Determining the energy values of feed ingredients for poultry is of great concern, especially since production efficiency is associated with profit margins. Therefore, accurate, precise, and reproducible energy values for feed ingredients are of the utmost importance in formulating an economical diet. An important aspect in determining the apparent metabolizable energy (AME) of a feed ingredient is the procedure employed in the drying of excreta samples. During sample preparation, substantial grinding losses were incurred amounting to 3.5 to 5.2% of the dried sample weight. Also moisture uptake during sample grinding accounted for a 1.9 to 3.9% increase in sample weight. To properly account for such losses, freshly collected excreta samples should be weighed, oven-dried at 40 C, reweighed, allowed to equilibrate with atmospheric moisture, weighed, ground, reweighed, and stored in air-tight containers for subsequent analyses. From the oven-drying of feed and excreta samples at various temperatures, a linear decrease in sample weight occurred with increasing drying temperatures. When dried at 100 C or less, the energy content of feed and excreta samples remained unchanged, but increased significantly at higher temperatures. The nitrogen composition of feed and excreta samples exhibited a similar trend, but a significant loss of excreta nitrogen (2%) occurred at 100 C. The loss of excreta nitrogen at a temperature of 100 C is of relatively minor consequence in the determination of metabolizable dry matter, but is of major concern in nitrogen balance studies. Extraction of feed and excreta samples with N,N-dimethylformamide and titration with Karl Fischer reagent indicated that significant amounts of water were retained by samples dried at 40, 60, and 80 C. However, at temperatures of 100 C or greater, little water was retained but sample decomposition occurred. A drying temperature of 90 C or the Karl Fischer method may yield a more accurate value for the dry matter of feed or excreta. When seven roosters were subjected to a total collection method for five consecutive days, individual birds were better metabolizers of dry matter and energy than others. By either a voluntary intake method or by a total collection method, values for the nitrogen-corrected metabolizable energy of corn were similar. The total collection method proved to be more reliable since it provided the least amount of variation when <u>ad libitum</u> feed intake and total excreta output were measured over a period of several days. In past experiments, adding fats to a test diet at the expense of cerelose in amounts no greater than 20% of the diet to determine the metabolizable energy of the fat has been associated with a high degree of variability. From the force-feeding of fats at levels to 100%, the variation associated with the metabolizable energy value of a fat was greatly reduced. The methodology presented here provided reliable estimates and detected differences between the metabolizable energy of two feed-grade fats in comparison to previous methods. / Ph. D. / incomplete_metadata

Experiments were conducted to investigate the effects of E. coli and rotavirus as causative agents in producing infectious stunting syndrome of poults. The syndrome, as it occurs commercially, was characterized in two experiments to produce decreased digestible dry matter and nitrogen as well as increased excreta nitrogen and gross energy content of affected poults. The effects of E. coli and rotavirus on the nutritional performance of poults were compared to the commercial syndrome by digestibility trials and assay of intestinal mucosaI enzyme activities. The strain of E. coli used in these experiments was isolated from the yolk sac of stunted poults. Inoculation of day-old poults was done orally in one experiment and via the yolk sac in another series of experiments. Experiments were designed in a factorial arrangement of E. coli inoculation and dietary protein level (28 vs. 22%). Oral administration of the pathogenic E. coli at a low dose (.1 ml of a 10⁻² dilution of a 24-hr culture) to day-old poults produced a significant increase in feed efficiency by 21 days of age for birds fed either 28 or 22°0 protein diets. In this case, E. coli apparently was established as part of the normal intestinal microflora of the turkey without producing a toxic response. Similar concentrations of E. coli (10⁻³ and 10⁻² dilutions) inoculated into the yolk sac of day-old poults resulted in significant mortality and morbidity. The lower dilution (10⁻³) produced the desired response of stunted poults without substantial mortality. Body weight gain and feed consumption were severely decreased by E. coli inoculation at both levels of protein (28 or 22%). The 28% protein diet alleviated the reduction in feed consumption for birds infected with the lower concentration of E. coli. The 10⁻² dilution caused substantial mortality and similar responses on body weight at both levels of protein. A malabsorption of nutrients accompanied E. coli infection in spite of reduced feed consumption as indicated by increased excreta nitrogen and gross energy content for all infected poults. In three experiments, rotavirus was orally inoculated into poults over 21 days of age previously fed either 28 or 22% protein diets. The response of rotavirus was variable in the three experiments, however, the low protein diet (22%) increased the poults susceptibility to rotavirus infection. Serum antibodies to rotavirus were detected in all poults tested prior to inoculation. Ubiquitous in nature, rotavirus appears to produce clinical signs of infection in combination with stress on the poults. Effects of rotavirus on digestibility parameters were inconclusive. In experiments with either rotavirus or E. coli, activities of intestinal mucosal enzymes were found to vary more between poults within a treatment than by any effect of the various treatments. / Ph. D.

Thesis (MScAgric)--University of Stellenbosch, 2000 / ENGLISH ABSTRACT: A flock of 500 Hybro broiler breeders were employed to study the effect of different levels of protein and energy on production and body composition. The daily lysine intake of the birds were 900, 1050, 1200 and 1350 mg respectively, each fed in diets with a daily energy intake of 1800 and 2000 kJ ME to provide a 4 x 2 factorial design. Lysine was used as the reference amino acid in the experiment and all other amino acids were kept in a constant ratio in every experimental diet. The total production was divided into 3 periods of 13 weeks each (week 23 - 35; week 36 - 48 and week 49 - 61) to determine the effect of the treatments over time. Production was evaluated by hen day production; egg weight (g/egg); egg mass (g/day); fertility; hatchability; chicks/hen/week; feed conversion and day old chick weight. Hen day production was significantly (P < 0,05) lower at the high energy intake for period week 49 to 61. Energy and protein levels significantly increased egg weight. Effect of protein was consistent during all three periods of production. Egg mass output had a significant (P < 0,05) response to increasing levels of protein for the total period of production. The birds on the high energy diet produced a significant higher egg mass per hen during the first period of production (week 23 - 35). Hatchability was reduced (P < 0,05) by the higher energy intake for the total period of production and this effect was very significant (P < 0,01) during the final period of production. Similar to hen day production, the higher energy had a significant (P < 0,05) negative effect on the amount of chicks produced. The well-known correlation between egg weight and chick weight was confirmed with the regression equation: Chick weight = 10,5 + 1,22 x Egg weight. Both energy and protein had a significant (P < 0,01) positive effect on chick weight. The feed conversion was lower at increasing levels of amino acid intake (P < 0,01). Higher energy intake significantly (P < 0,05) increased hen weight and protein had a very significant effect during the first period of production (P < 0,01). The isotope dilution technique (tritiated water) was used to estimate the body composition of the breeders. This was done at 5 different periods (week 27, 35, 43, 52 and 61) of the production period to establish changes in requirements over time. Significant correlation were found between carcass moisture and waterspace (R2 = 0,76); fat % and carcass moisture (R2 = 0,78); protein % and waterspace (R2 = 0,35) and fat % and waterspace (R2 = 0,46). The regression equations obtained from these correlation were employed to determine excess energy and lysine consumed at different ages. Energy requirements were calculated according to the effective energy (EE) system and the conventional ME system. According to effective energy the lower energy intake was not sufficient and the maximum requirement was calculated to be 1942 kj EE/day. The metabolizable energy calculations indicated sufficient intakes at every treatment with the maximum requirement 1746 kj ME/day. The lysine requirement was found to be in excess of 1050 mg lysine per day. The recommendation for daily lysine intake is 1200 mg/day and the energy intake of breeders should be 1900 to 2000 kj ME/day from week 23 to 35 and can be reduced to 1800 kj ME/day in the final period of production. / AFRIKAANSE OPSOMMING: Om die effek van verskillende vlakke energie en proteïen op produksie en liggaamsamestelling te ondersoek is 'n trop van 500 Hybro braaikuiken teelouers gebruik. Die daaglikse lisien inname van die henne was onderskeidelik 900, 1050, 1200 en 1350 mg, wat elk by 'n daaglikse energie inname van 1800 en 2000 kJ ME verskaf is, in 'n 4 x 2 faktoriale ontwerp. Alle aminosure is in 'n konstante verhouding met die verwysings aminosuur lisien in die rantsoen ingesluit. Om te evalueer of daar veranderinge oor 'n tydperk plaasvind weens die verskillende behandelings is die produksie periode in drie periodes van 13 weke elk verdeel (week 23 - 35; week 36 - 48 en week 49 - 61). Die produksie standaarde wat gemeet is, is hen dag produksie, eiergewig (g/eier), eiermassa (g/dag), vrugbaarheid, uitbroeibaarheid, kuikens/hen/week, voeromset en dagoud kuikenmassa. Hen dag produksie was betekenisvol (P < 0,05) laer by die hoër energie innames in die laaste periode van 49 tot 61 weke. Energie en proteïen het eiergewig betekenisvol (P < 0,01) verhoog. Die effek van hoër vlakke proteïen was konstant in alle produksie periodes. Die daaglikse eiermassa (g/dag) het ook saam met stygende vlakke proteïen verhoog en hierdie effek was vir die totale periode van produksie. Energie het die eiermassa in die eerste periode van produksie (week 23 - 35) verhoog. Uitbroeibaarheid is verlaag (P < 0,05) vir die totale periode van produksie deur die hoër energie inname en die effek was selfs groter (P < 0,01) in die finale periode van produksie. In ooreenstemming met die hen dag produksie is die aantal kuikens geproduseer negatief beïnvloed deur die hoër energie inname (P < 0,05). Die korrelasie wat bestaan tussen eiermassa en kuikenmassa is bevestig deur die regressie: Kuikenmassa = 10,5 + 1,22 x Eiermassa. Energie en proteïen het kuikenmassa betekenisvol (P < 0,01) verhoog. Voeromset was laer by stygende vlakke van proteïen inname (P < 0,01). Die hoër energie inname het henmassa ook betekenisvol (P < 0,05) verhoog en proteïen het dieselfde effek slegs in die eerste periode van produksie gehad (P < 0,01). Die liggaamsamestelling van teelhenne is bepaal met behulp van die isotoop verdunnings tegniek (tritium water). Dit is bepaal op 5 verskillende stadiums in die produksie periode (week 27, 35, 43, 52 en 61) om die moontlike verandering in behoeftes oor tyd vas te stel. Betekenisvolle korrelasies is gevind tussen karkasvog en die waterspasie (RZ= 0,76); vet % en karkasvog (R2 = 0,78); proteïen % en waterspasie (R2 = 0,35) en vet % en waterspasie (R2 = 0,46). Die regressie vergelykings van hierdie korrelasies is gebruik om die hoevelheid surplus energie en lisien ingeneem te bepaal. Die" effective energy" sisteem en die konvensionele ME sisteem is gebruik in die bepaling van energie behoeftes. Volgens die " effective energy" was die energie inname nie voldoende by die laer energie innames nie en die maksimum behoefte is bereken as 1942 kJ EE/dag. Die maksimum energie behoefte volgens metaboliseerbare energie is bereken as 1746 kj ME/dag. Die lisien behoefte moet hoër as 1050 mg/dag wees. Die aanbeveling van die daaglikse lisien inname is 1200 mg/dag en die energie inname moet 1900 tot 2000 kj/dag wees tot 35 weke produksie en kan daarna verlaag word na 1800 kJ ME/dag.

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