Six experiments were carried out with Single Comb White Leghorn laying chickens to assess the effect of feeding a source of direct-fed microbials (Lactobacillus; Lacto) and its carrier [condensed cane molasses solubles (CCMS)] on the retentions of fat, nitrogen and several minerals; on the status of the pH of the gastrointestinal (GI) tract; on the phytase activities in the Lacto and in the crop and in the intestinal contents and intestinal, pancreatic and liver tissues; on the histological and anatomical changes of the GI tract and on the production performance. Feeding 1,100 mg Lacto/kg diet (ppm) and 2,200 ppm Lacto in corn-soya bean meal (C-S) diets to layers stimulated appetite, improved egg production (in Experiment 1 only), egg mass, egg weight, egg size, internal egg quality and fat, nitrogen, calcium and phosphorus retentions (P < .05). Production performances were not different between the layers fed the 1,100 ppm diet and those fed the 2,200 ppm Lacto diet. Supplementing Lacto diets with 1 and 3% fat reduced feed consumption, provided better feed conversion, egg production, egg masses, egg size, body weight gains, and nitrogen, calcium and phosphorus retentions. Feeding 1,100 ppm Lacto barley-corn-soya bean (B-C-S) layer diets improved body weight gains and the retentions of fat, phosphorus and manganese and increased the rate of passage of digesta (P < .05). Feeding Lacto C-S and Lacto B-C-S layer diets increased cellularity of Peyer's patches in the ileums of the layers which may stimulate the mucosal immune system. No changes in length and weight of the intestine were observed. Daily feed consumption and body weight gains were improved when pullets were fed 1,100 ppm Lacto from 7 to 19 wk of age (WOA). When these pullets were continued on the Lacto feed during the laying period (20 to 59 WOA), increased feed consumption, egg size, nitrogen and calcium retentions, increased cellularity of Peyer's patches, decreased length and weight of intestine were observed (P < .05). Presence of phytase activity was higher in condensed cane molasses solubles (CCMS)- Lactobacillus premix than the carrier (CCMS). Feeding the CCMS-Lacto diets to layers decreased the pH of the GI tract, increased phytase activities in the GI tract and intestinal tissues and improved shell thickness and phosphorus retention (P < .05). The production performance of layers fed .45% and .25% available phosphorus (AP) diets were not different except for body weight gain. Phosphorus retention was better for layers fed diets containing .25% AP with CCMS-Lacto than the .45% AP control diet. According to these studies, feeding Lacto to pullets and layers improved their performance and the retention of nutrients such as calcium, phosphorus and nitrogen which subsequently reduced the cost of feeding. / Graduation date: 1994

The influence of microbial phytase on growth performance, availability of macro and trace minerals, apparent ileal digestibility (AID) and apparent "fecal" digestibility (AFD) of amino acids (AA) and CP were investigated. The optimum level of dietary Ca and P for the maximum efficacy of supplemental phytase in broiler chickens was also studied. Phytase supplementation (600 U/kg) to a low P diet increased $(P 0.05)$ on feed efficiency in broiler chickens at 21 d. The efficacy of phytase, particularly in stimulating growth, was higher in male than female chickens. The relative retention of Ca, P, Cu, Zn and N increased by addition of phytase to a low P diet but phytase had no effect $(P >0.05)$ on the retention of Mg, Mn and Fe. Phytase supplementation increased $(P 0.05)$ on plasma Zn, Cu, and Mg. Phytase increased $(P 0.05)$ on mineral proportions in the tibia ash; however, it increased $(P 0.05)$ on AID of any of the AA in male chickens. Addition of phytase did not have any effect $(P > 0.05)$ on AFD of any of the AA in male chickens but increased $(P 0.05)$ on either AID or AFD of CP and AA at 21-d. In summary, phytase supplementation increased the growth performance, availability of P, Ca, Cu, Zn and N, plasma P, and tibia ash and reduced plasma Ca; it also increased the AID and AFD of most of the AA, particularly in female chickens at 28-d. The efficacy of microbial phytase was high when dietary P and Ca levels were low.

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Rainbow trout, about one-year-old, were fed diets containing either glucose (C) or herring oil (F) as the non-protein energy source for a period of two weeks. As well, they were fed each diet at satiation (C-2, F-2) and at levels half that (C-l, F-l). The trout were subsequently fasted and sampled for tissue glycogen, protein, dry matter and glucose-6-phosphatase activity at full feeding and at 2, 4, 8, 10, 13 and 16 days of fasting. The livers of the C-fed fish had 12% wet weight glycogen and the livers of the F-fed fish had 3% wet weight glycogen at full feeding. Upon fasting, glycogen concentrations in the F-fed fish livers fell to basal levels of 1% by 2 days while glycogen concentrations in the C-fed fish livers fell to basal levels only after 10 days. The protein concentration in the trout livers was inversely related to the glycogen concentration. The amount of liver protein in the trout carcass, however, was directly related to dietary carbohydrate levels. Trout liver glucose-6-phosphatase activity increased as fasting progressed but there were no treatment differences in enzyme activity. The muscle of the C-2 fed trout contained .4% glycogen at full feeding. The muscle of the other dietary treatments contained .1-.15% glycogen. It appears that trout muscle stored dietary carbohydrate that was not taken up by the liver or that was not oxidized. Upon fasting there was a depletion in muscle glycogen to basal levels of .05% after 4 days. Thereafter there occurred a rebound in muscle glycogen to levels at or greater than full-fed levels followed by a decline back to basal values. The rebound was greater and peaked earlier (8 days) in the C-fed trout than in the F-fed trout (10 days). Broiler (BR) and White Leghorn (WL) pullet chicks were fed diets, where 25% of the energy was supplied as corn starch (C) or corn oil (F), for a three-week period. The chicks were then fasted and sampled for tissue glycogen, protein and dry matter at full feeding and at 8, 16, 24, 32, 44, 56, 80, 104 and 128 hours of fasting. The BR livers contained more glycogen (3%) than the WL livers (2%) and the C-fed chicks had greater liver glycogen concentrations (3%) than the F-fed chicks (2%) at full feeding. Upon fasting, liver glycogen fell to basal levels of .03% after 8 hours. Thereafter there was a rebound increase in liver glycogen levels to a peak of 1% and a subsequent tapering off. The rebound occurred earlier in the C-fed chicks than in the F-fed chicks. The peak was attained earlier in the WL (32-44 hours) than in the BR (50 hours). The amount of liver protein in the C-fed chicks was higher than that in the F-fed chicks over the entire fasting period. Chick muscle glycogen concentrations were initially higher in the C-fed than in the F-fed chicks and higher in BR (1.2%) than in WL (.8%). Upon fasting, BR muscle glycogen concentrations were maintained while those of WL fell to .3%. There were erratic fluctuations in muscle glycogen levels. / Land and Food Systems, Faculty of / Graduate

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Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Antibiotic growth promoters (AGP’s) have been used in feed of production animals to improve their growth performance and disease resistance. However, there has been an increase in the presence of antibiotic residue in animal products, as well as an increase in untreatable illnesses due to antibiotic resistant bacteria. This led to the European Union banning the use of antibiotic growth promoters, in production animals, in 2006. An alternative to AGP’s is therefore needed in animal feed in order to maintain performance. Plant extracts and essential oils have gained much attention, due to their natural antimicrobial, antibacterial, anticoccidial and antioxidant properties. This study tested the efficiency of Ateli plus®, an oregano plant extract based product, as a replacement to AGP’s on production parameters, carcass characteristics and organ and gut health of broilers. This study consisted of five treatments fed to broilers from hatch till 33 days of age, fed in three phases; starter, grower and finisher. The treatment diets consisted of a negative control (no AGP), positive control (AGP), Ateli plus® at 1kg/ton (Ateli plus® min), Ateli plus® at 2kg/ton for week one followed by 1kg/ton for the remainder of the period (Ateli plus® max), and AGP plus Ateli plus® max (AGP plus Ateli plus® max). Results from this study show that there was no difference in performance parameters between treatments. The performance parameters tested included liveability, average daily gain (ADG), average weekly feed intake, average cumulative feed intake, average weekly live weight, average cumulative weight gains, feed conversion ratio (FCR), cumulative FCR and the European production efficiency factor (EPEF). Broiler breast and thigh muscle pH and colour (L*, a* and b*) reading values were measured, showing a trend for improved L* colour reading value and ultimate pH, in broilers supplemented with Ateli plus®. This leads to an increase in water binding capacity and tenderness, therefore resulting in an improvement in meat quality. No differences were shown for dressing percentage and portion percentages relative to carcass weight. No significant differences were seen for tibia bone Ca and P content, or tibia bone fat, moisture or ash percentages. However a significant decrease in tibia bone strength was found in all broilers supplemented with Ateli plus® diets and the negative control diet, compared to AGP supplemented broilers. Gut morphology showed no consistent effect of treatment on villi height or crypt depth of the duodenum, jejunum and ileum. No significant differences between treatments were found for organ pH or organ weights, except the gizzard, which was heavier for Ateli plus® max supplemented broilers. Ateli plus® shows promise on improving meat quality characteristics of broilers, however the significant decrease in tibia bone strength in Ateli plus® supplemented broilers is a major concern and needs to be researched further. Ateli plus® acts as a good AGP replacement, as broiler performance for the Ateli plus® supplemented broilers was maintained, and not decreased, when compared to the AGP supplemented broilers. However, the broilers fed the negative control diet had performance parameters statistically equal to both the Ateli plus® and AGP supplemented broilers, as well as no significant differences between organ weights were found. It can therefore be said that the broilers were raised under good management, and their optimal environmental conditions. Therefore conclusive effectiveness of Ateli plus® as a replacement for AGP on broiler performance cannot be reported from this study. / AFRIKAANSE OPSOMMING: Antibiotiese groeistimulante (AGP’s) word gereeld as voerbymiddels vir diere gebruik om groei en siekte weerstandbiedenheid te verbeter. Die verbod op die gebruik van antibiotika as 'n groeipromotor in die Europese Unie (sedert 2006) kan toegeskryf word aan die toename in onbehandelbare siektes as gevolg van weerstandbiedende bakterieë, asook die teenwoordigheid van residue in die dierlike produkte. Alternatiewe vir AGP’s in dierevoeding word dus benodig om produksie te handhaaf. Plant ekstrakte en essensiële olies het baie aandag gekry as gevolg van hul natuurlike antimikrobiese, antibakteriële, antikoksidiese en antioksidatiewe eienskappe. 'n Studie is gedoen om die doeltreffendheid van Ateli plus® ('n origanum plant ekstrak gebaseerde produk) op groei produksie parameters, karkaseienskappe, orgaan- en dermgesondheid te bepaal wanneer Ateli plus® as 'n AGP plaasvervanger in die dieëte van braaikuikens gebruik word. Gedurende die proef was vyf verskillende diëte/behandelings vir 33 dae vir braaikuikens gevoer. Die behandelings het bestaan uit 'n negatiewe kontrole (geen AGP), positiewe kontrole (AGP), Ateli plus® teen 1kg/ton (Ateli plus min), Ateli plus® teen 2kg/ton vir die eerste week gevolg deur 1kg/ton vir die res van die tydperk (Ateli plus® max), en AGP plus Ateli plus® max (AGP plus Ateli plus® max). Resultate van hierdie studie toon dat behandelings nie 'n effek op produksie parameters gehad het nie. Die groei produksie parameters wat getoets is sluit in oorlewing, gemiddelde daaglikse toename (GDT), die gemiddelde weeklikse voer-inname, gemiddelde kumulatiewe voerinname, gemiddelde weeklikse lewendige massa, gemiddelde kumulatiewe gewig toename, voeromsetverhouding (VOV) en die Europese produksie doeltreffendheid faktor (EPEF). Die pH en kleur (L*,a* en b* waardes) van die dy- en borsspier is gemeet. Ateli plus® aanvulling in braaikuiken diëte het 'n tendens getoon vir verbeterde L * en finale pH waardes in die spiere, wat lei tot 'n toename in waterhouvermoë en sagtheid en dus verbeterde vleiskwaliteit. Geen verskille tussen behandelings is gevind vir uitslagpersentasie en die massa van porsies (uitgedruk as persentasie relatief tot karkasgewig) nie. Behandelings het nie 'n effek op die vet, vog, as persentasies of Ca- en P-inhoud van die tibia gehad nie. In vergelyking met AGP aangevulde braaikuikens, is 'n beduidende afname in die tibia breeksterkte van kuikens in die negatiwe kontrole groep en kuikens wat met Ateli plus® aangevul is, gevind. Spysverteringskanaal morfologie het getoon dat behandeling geen konsekwente effek op villi hoogte of krip diepte van die duodenum, jejunum en ileum gehad het nie. Slegs die krop massas van kuikens wat met Ateli plus® max aangevul is, was swaarder in vergelyking met hoenders in die ander behandelings; verder is geen beduidende verskille tussen behandelings gevind vir orgaan pH of orgaan gewigte nie.

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