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.

Four experiments were carried out with broiler chicks from day-old to three or four weeks of age to assess the effects of nitrates and nitrites from calcium, potassium, and sodium salts in the drinking water of broilers on growth, body weights, feed utilization, blood chemistries, liver tissues, and lipid oxidation of breast and thigh tissues. Body weights were lower (P<.05) among chicks consuming calcium nitrate than those of chicks consuming sodium nitrate or the control. Chicks consuming calcium nitrate (Ca(NO���)���) at 1000 ppm had lower (P<.05) body weights than those drinking Ca(NO���)��� at 0, 50, or 200 ppm. Broilers receiving 1000 ppm of calcium nitrite (Ca(NO���)���) had depressed body weights when compared to chicks consuming 0, 50, or 200 ppm of Ca(NO���)���. Consumption of sodium nitrate (NaNO���) at 2033 ppm reduced (P<.05) broiler weights in comparison to broilers ingesting 0, 111, or 427 ppm of NaNO���. Feed utilization was less efficient (P<.05) by chicks ingesting Ca(NO���)��� and calcium, potassium, or sodium salts of nitrite when compared with the control. / Graduation date: 1996

Assignment (MPhil)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The aim of this study was to evaluate the performance and profitability of different dietary specifications for broiler chickens slaughtered at 35 days of age. Two trials were performed to evaluate different production parameters. The results of these trials were compared to the predicted results of the EFG broiler model. No carcass data were available for the two trials mentioned above. Therefore, in order to evaluate the accuracy of the broiler model when predicting carcass characteristics, two published data sets (Leeson et al., 1996a) were used. Predicted and actual values were compared, evaluated and discussed. Two broiler trials were performed. In Trial One the amino acid density decreased throughout the range of three treatments from prestarter to finisher diets. In Trial Two the amino acid density decreased only in the four finisher diets. The main difference between predicted and actual results was the response to body weight. The model predicted a steady increase in feed intake to compensate for the lower dietary specifications while body weight did not change significantly. This increase in feed intake seems to be enough to maintain body weight. Trial birds also increased their feed intake as dietary amino acid density decreased, but this compensation seemed to be too low to maintain body weight compared to the control diet. The birds may find it easier to compensate when they have time to adapt to the specification. There is evidence in the literature that birds need seven days to adapt their feed intake to a lower feed specification (Leeson et al., 1996a). It can be speculated that the trial birds started to loose body weight due to a lower amino acid intake in this period. The model seems to adapt feed intake immediately after a change in diet specification. The simulation on literature data lead to the following conclusions: 1) Broilers posses the capacity to increase their feed intake with at least 65% should finisher diets with lower amino acid and energy concentrations be supplied. If only the energy concentration of finisher diets were decreased, the increase in feed intake will be around 30%. (see Table 16 and 23) 2) The accurate prediction of feed intake from the given dietary specification has a major influence on the accuracy of the prediction of broiler performance. 3) Amino acid density and DLys:ME ratio plays a significant role in the control and prediction of feed intake. The EFG broiler model is based on sound scientific principles. The model is comprehensive and can be used for a wide range of environmental and management conditions as well as dietary conditions. The nutritionist can use the model with confidence to assist in practical feed formulation. The actual strength of the model lies in the time and money being saved compared to practical trials. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om die prestasie en winsgewendheid van braaikuikens te bepaal wanneer voere met verskillende digthede tot op 35 dae gevoer word. Twee eksperimente is uitgevoer om produksieresultate te evalueer. Die resultate van hierdie eksperimente is met die voorspelde waardes uit die EFG simulasie-model vergelyk. Aangesien geen karkasdata vir bogenoemde eksperimente beskikbaar was nie, is twee gepubliseerde datastelle gebruik om hierdie deel van die model te evalueer (Leeson et al., 1996a). Twee braaikuiken eksperimente is uitgevoer. Eksperiment Een het uit drie behandelings bestaan waarvan die aminosuur-konsentrasie vanaf dag een tussen behandelings verskil het. In Eksperiment Twee het die aminosuur-konsentrasie net in die vier afrondingsdiëte verskil. Liggaamsmassa op 35 dae het die grooste verskil tussen voorspelde- en werklike waardes getoon. Beide voorspelde en werklike innames het in albei eksperimente verhoog soos wat aminosuur-konsentrasie afgeneem het. Voorspelde liggaamsmassa het egter konstant gebly terwyl werklike data 'n afname in liggaamsmassa getoon het. Dit bleik dat die voorspelde toename in innames voldoende was om massa te onderhou terwyl die voëls in werklikheid nie genoeg gekompenseer het nie. Leeson et al., 1996a het tot die gevolgtrekking gekom dat braaikuikens minstens sewe dae benodig om hul voeriname by 'n nuwe spesifikasie aan te pas. So 'n stadige aanpassing kan daartoe lei dat energie- en aminosuur-inname daal indien 'n dieet met laer spesifikasie gevoer. Dit sal daartoe lei dat die kuikens liggaamsmassa verloor. Uit die literatuur simulasies is die volgende afleidings gemaak: 1) Braaikuikens besit die vermoeë om voerinname in die afrondingstyd met minstens 65% te verhoog indien 'n afrondingvoer met laer amiosuur- asook energiekonsentrasie gevoer word. Indien net die energiekonsentrasie verlaag word, sal die inname met sowat 30% verhoog. 2) Die akkurate voorspelling van inname is krities vir die akkurate voorspelling van produksieparameters. 3) Aminosuur-digtheid en DLys:ME speel 'n belangrike rol in die beheer en voorspelling van voerinname by braaikuikens. Die EFG braaikuikenmodel is op suiwer wetenskaplike beginsels geskoei. Die model is omvattend en kan vir 'n wye reeks van omgewings- en bestuurstoestande asook dieet-spesifikasies gebruik word. Die voedingkundige kan die model met vertroue gebruik om met praktiese voerformulering by te staan. Die model kan die formuleerder baie tyd spaar aangesien praktiese eksperimente ingeperk kan word.

Thesis (MPhil)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The study investigated the performance of broiler production III two enterprises around Gaborone. The main emphasis was on performance and feed efficiency of four major production parameters, which include feed intake (FI), age at slaughter, body weight (BW) and feed conversion ratio (FeR). The averages for slaughter age, BW (live weight), FI and FeR for the two enterprises combined were 39.6 days, 1.8 kg, 3.41 kglbird and 1.96, respectively. For the entire rearing period the average performance efficiency factor for the two enterprises was 224. The results of the current study showed that age at slaughter, BW, cumulative FI, FeR and mortality in the two farms declined significantly (P<O.OOI) over time. These improvements in performance may be ascribable to the genetic improvements of the broiler bird for fast growth, improved nutritional status as well as efficiency in management on the part of producers. / AFRIKAANSE OPSOMMING: Die studie ondersoek die vordering van braaikuiken produksie in twee ondernemings in die omgewing van Gabarone. Die klem was op die prestasie en voer doeltreffendheid van vier groot produksie parameters. Die parameters sluit in; voerinname (VI), ouderdom by slag, liggaamsmassa (LM), en voeromsettings verhouding (VOV). Die gekombineerde gemiddeldes vir die twee ondernemings vir slagouderdom, LM (lewende massa), VI en VOV was onderskeidelik 39.6 dae, 1.8 kg, 3.41 kg/voël en 1.96. Die gemiddelde prestasie doeltreffendheidsfaktor vir die twee ondernemings, vir die hele groei periode, was 224. Die resultate van die studie het daarop gedui dat ouderdom by slag, LM, kumulatiewe VI, VOV en mortaliteite aansienlik afgeneem (P<O.OOI) het oor tyd. Hierdie verbeteringe in vordering kan toegeskryf word aan die genetiese verbeteringe van die braaikuiken voël vir vinnige groei, verbeterde voedingstatus, sowel as doeltreffendheid in bestuur vanaf die produseerders.

In broiler operations, various health problems develop during the final two weeks of the growing period, resulting in increased mortality and condemnation losses. At this stage, sickly birds were found to be systemically infected by various bacteria regardless of varied clinical signs. The main objective of the present study was to determine the prevalence and nature of systemic bacterial infections in unthrifty commercial broiler chickens and to establish a reproducible infection model in the laboratory. Thirty-one unthrifty 6-week-old broilers were obtained from three farms, and bacterial isolations were conducted on blood, liver, and hock joint. Bacteria were isolated from 87, 90, and 71% of the blood, liver and hock joint samples, respectively. Mean bacterial counts (log������ CFU/ml or g) of the blood and liver were 2.15 and 2.93, respectively. Among 132 bacterial isolates, major species were; Staphylococcus (60%), Corynebacterium (18%), Escherichia coli (5%), and Stomatococcus (4%). Among 79 Staphylococcus isolates, 77 were coagulase-negative. Major species of staphylococci were; S. lentus (19%), S. simulans (18%), S. cohnii (13%), S. gallinarum (10%) and S. captis (7%). In addition, 6 species of gram-positive and 5 species of gram-negative organisms were isolated. Apparently systemic infections were not caused by predominant pathogenic bacterial species, and adequately described as mixed infections. However, there were some significant relationships between isolated bacterial species and sampling sites, suggesting that certain organisms were abundant in the environment of a particular poultry house. These results indicate that systemic infections in market age broilers are caused by mixed bacterial species and suggest that they are caused by suppressed host antibacterial systems rather than pathogenic factors of microorganisms. Antibiotic susceptibility results showed 100% susceptibility of staphylococcal isolates (n=69) against vancomycin and enrofloxacin. Of these coagulase negative staphylococci showed 19% and 73% resistance against methicillin and penicillin G, respectively. There was also heterogeneity in antibiogram profiles within species of coagulase-negative staphylococci. Pathogenicity of representative field isolates from the above described study was tested in 5-day-old embryonated eggs and in 3- week-old broiler chicks. Consistent lethality was demonstrated with S. aureus in embryos. Staphylococcus intermedius or S. lentus demonstrated some pathogenicity, while S. gallinarum or Corynebacterium were non-pathogenic in embryos. In 3-week-old broilers, however, only S. aureus caused septicemia and death; other bacterial species mentioned above caused neither clinical signs of acute or chronic staphylococcosis nor mortality. / Graduation date: 1998

Endotoxin is a part of the cell wall of gram-negative bacteria, consisting of serotype-specific polysaccharide, core oligosaccharide, and lipid A. Lipid A is responsible for an array of pathophysiologic reactions in animal hosts. Amebocyte lysate originated from Limulus polyphemus (horseshoe crab) has been used extensively in various assay systems to detect endotoxin. One of the assays, a chromogenic Limulus amebocyte lysate (CLAL) test was developed in 1978 and has been used extensively in human clinical fields for its high sensitivity and ease in quantitation. The use of the CLAL test in veterinary fields has been limited to dogs, horses and cattle. The objective of the thesis research was to determine the level of endotoxin by the CLAL assay in broiler chickens. Since gram-negative septicemia is common in broiler chickens, the detection of endotoxemia would help in understanding the pathogenesis and in developing a new treatment or prophylactic mean. By the use of a kinetic method, the CLAL assay detected the standard endotoxin (phenol-water extract from Escherichia coli, 055:B5 strain) in the range between 100 ng and 10 pg/ml. The intra-assay variation was 1.2% and interassay variation was 18.8% based on 1.0 ng standard. The control showed spontaneous release of the chromophore starting around 40 min. after the start of the reaction. This spontaneous release was found not due to contamination of pyrogen-free water (PFW) or substrate by endotoxin. With chicken plasma, various non-specific reactions were detected. Plasma alone released the chromophore in a slow, steady manner, but this reaction was virtually eliminated by heating at 100 C. Chicken plasma contained both inhibitor(s) and enhancer(s) for the test. Endotoxin-free plasma samples were prepared by absorption and reconstituted with 1.0 ng/ml of endotoxin. After 1:10 dilution in PFW, heating (10 min.) at 100 C was found most adequate to inactivate these factors as compared with heating to 70 or 85 C. With plasma samples which had been diluted and heated at 100 C, however, still some nonspecific reaction was detected; the lysate, in the absence of substrate, caused some precipitates with chicken plasma in a nonspecific manner, making it difficult to interpret the OD readings. Because of these nonspecific reactions largely inherent to the state of lysate, sensitivity was judged only to 100 pg endotoxin/ml of chicken plasma. A commercial test kit also showed 100 pg/ml sensitivity with the end point method, but found unreliable since proper controls cannot be evaluated in a similar manner as the kinetic method. Thirty chicken plasma were collected from 3 local broiler farms and was judged to contain less than 100 pg/ml in 29 birds, while one bird showed 12.0 ng/ml of endotoxin. Twenty-three per cent of the chickens showed gram-negative bacteremia without detectable endotoxemia, and the bird with endotoxemia did not have bacteremia. One microgram of the standard endotoxin was injected intravenously to 20 broiler chickens raised in the laboratory, and 5 were sacrificed at 2, 30, 60, and 90 minutes after the injection. The endotoxin was found to be cleared from the blood at the rate of 152 pg/min. To increase the sensitivity and to decrease the cost of the CLAL test, future efforts should be made; 1) to significantly decrease the nonspecific reaction between the lysate and substrate; and 2) to block the precipitation or clotting reaction between the lysate and chicken plasma. If these nonspecific reactions be controlled, the CLAL test could be run in a simple end-point method and/or in an automated manner with chicken plasma. / Graduation date: 1997

Today's consumers have shown a greater concern in the relationship between dietary fat and human health. The demand for leaner meat is continuously on the rise. The reduction of fat deposits in the abdominal area of ready-to-cook fryers, considered a waste product in the poultry industry, has become a major opportunity for the researcher. Experiments were conducted to evaluate the merit of managerial practices affecting abdominal fat (AF) levels in broiler chickens. Factors studied included seasons of the year, source of the commercial broiler strain crosses, stocking densities, lighting systems, types of housing, dietary salt (NaCl) 1eve1s and feed restriction. Two housing types (open-sided and windowless) and different seasons were utilized to evaluate the influence on broiler performance and AF levels. Raising broilers from the same strain cross in an open-sided building did not affect performance and AF levels. Mean body weight (BW) were highest in fall season (1929 g ) and lowest in summer (1735 g) (p<.05) while highest and lowest % AF revels were observed in spring and winter (2.34, and 1.42 respectively). The comparative effect of feeding regime, (full feed, FF), 95 and 90% FF), dietary salt 1evels (0, 0.25, and 0.5% of the finisher diet), stocking densities (0.06, 0.07, and 0.09 m�� of floor space per bird) and type of housing (battery cages and litter pens) were examined on broiler performance and AF lever. Ninety % FF resulted in significantly lower body weights and AF levers compared to ad libitum feeding. At 49 days of age, mean BW of broilers fed 0.5% salt were higher (P<.05) than the group not provided with salt. Altering stocking densities and rearing in battery cages failed to show any significant improvements performance and % AF. Lighting regime 12 h light (L): 12 h dark (D), recycled during the rearing period resulted in lower (p<.05) mean BW than continuous lighting regime (CL) when applied from 5 days of age. Broilers raised on 16L:8D after 21 days had comparable performance to CL. Lighting regime of 12L:12D, recycled in combination with increasing stocking densities from 0. 06 to 0.8 m�� floor space/broiler and intermittent righting of lL:3D in combination with the addition of 0.5% salt to the diet resulted in improved (P<.05) BW with no corresponding increases in AF levels. Factors such as season of the year, feeding of salt, and manipulation of light (up to 8 h dark) can be used as tools in reducing % AF and overall production costs. / Graduation date: 1993

Growth hormone binding protein (GHBP) may be an important factor in the regulation of growth as well as an indirect, less invasive way of predicting the status of growth hormone receptors. Several factors (age, nutritional status, sex, and glucocorticoid administration) have been reported to influence circulating growth hormone (GH) levels, growth hormone receptor (GHR) activity and/or GHBP in mammalian species. Therefore, the studies conducted in this research were designed to determine if these factors have any affect on serum GHBP in the young broiler chicken. Serum GHBP activity was expressed as a percent specifically bound ¹²⁵IhGH (%SB), as measured by a dextran-coated charcoal assay. Serum GHBP activity was highest (mean %SB= 14.6 ± 1.2) at hatch aniedecreased linearly (r= -.9516) to 4 wk of age (mean %SB= 4.1 ± 0.6). Sex had no significant affect on serum GHBP activity from hatch to 4 wk of age. Short term nutrient deprivation (24 h fast) of 4 wk old birds had no significant affect on serum GHBP activity, nor did refeeding. Feeding birds nutrient poor diets (low energy, low protein or low energy and low protein) did not significantly affect serum GHBP activity when compared to birds fed a commercial broiler diet. Pulsatile delivery of cortisone acetate (1, 5 and 10 mg/d/b) had no affect on serum GHBP activity at any dose. These results suggest that serum GHBP activity in the chicken is not affected by many factors which do influence GHBP in mammalian species. The lack of response to nutrient deprivation and cortisone acetate may be a factor related to the age of the birds used in these studies. / Graduation date: 1993

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 99-109). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 99-109). Also available on the Internet.