The objective of this work was to define the effects of dietary energy intake on broiler fat deposition and metabolism. Fatty broilers are one of the major problems in the broiler industry. The effects of changing calorie to protein (Cal/Pr) ratios, and the addition of cellulose or dried distiller's byproduct (DDBP) in the diet, on abdominal fat deposition, liver lipogenesis and glucose oxidation and broiler performance indicated that the mean body weight of broilers fed narrower Cal/Pr ratio diets (124 and 143 for starter and grower, respectively) were lower (P<.01) than broilers fed diets with mid-Cal/Pr ratios (138 and 160) and wide Cal/Pr ratios (147 and 171). Feed conversion was better (P<.01) for broilers fed the diet with wide Cal/Pr ratio than the broilers fed the diet with narrow Cal/Pr ratio. Abdominal fat deposition increased (P<.001) with wide Cal/Pr ratio than narrow Cal/Pr ratio. No significant differences were found in in vitro liver lipogenesis and glucose oxidation when Cal/Pr ratio was widened. Mean body weight, feed conversion and abdominal fat levels of broilers fed 5% cellulose or 10% DDBP diets were not different when compared to broilers fed diets with the same Cal/Pr ratio without these two feed ingredients. The time-course of the deposition of abdominal fat fitted a negative exponential growth curve. The data also indicated that the highest potential for abdominal fat deposition was during the first two weeks of age. When the feed intakes of broilers were restricted for a 6 day period beginning at 1, 2, 3 and 4 weeks of age, the feed efficiencies of all the restricted broilers were significantly improved compared with broilers fed ad libitum. No significant differences were observed in mean body weight between the different treatments. The percentage of abdominal fat in broilers restricted-fed starting either at 1 or 2 weeks old for a 6-day period were lower (P<.05) than broilers fed ad libitum. Feed restriction from days 7 to 12 reduced the adipocyte size but not the number. Feed restriction decreased (P<.05) lipogenesis at 2 and 8 weeks of age. No significant effects were found in lipolysis between the restricted and ad libitum-fed broilers. These studies demonstrate that early feed restriction (days 7 to 12) reduced abdominal fat deposition which is attributed to the reduction in the adipocyte size. Smaller size adipocyte resulted from decreased activity of lipogenesis. / Graduation date: 1991

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.

Seven experiments were carried out to investigate the involvement of carbohydrate and lipid metabolism on the incidence of Sudden Death Syndrome (SDS) in broiler chickens. Hepatic arachidonate level decreased after 1 h postmortem. The decreased level of hepatic arachidonate previously observed in SDS birds was, therefore, associated with the post-mortem aging. Broiler chickens fed diets high in glucose monohydrate (cerelose) were more susceptible to SDS mortality than broilers fed diets high in corn starch or corn-soy. Feeding broilers a high cerelose diet increased the levels of plasma calcium, total protein, triacylglycerol, and uric acid compared to broilers fed corn starch diet. Broilers fed cerelose diet also showed the higher incidence of leg abnormality than broilers fed corn starch or corn-soy diets. Daily intraperitoneal injection with 0.25 ml of L(+) lactic acid solution (100 mg lactic acid/ml) to broilers over a 7-d period failed to reproduce the SDS incidence, whereas intravenous injection of 40% lactic acid solution (200 mg lactic acid/kg body weight) resulted in 100% incidence of SDS-type mortality. No SDS-type mortality was observed with the intravenous injection of 40% sodium lactate solution (200 mg sodium lactate/kg body weight). Disturbance of physiological acid-base balance might be a factor in the SDS-type mortality. Suboptimal thiamin level in broilers fed cerelose diets was observed. Thiamin supplementation to cerelose diet improved the thiamin status of the broilers. Mortality due to SDS was decreased when thiamin hydrochloride was supplemented to cerelose diet at the level of 0.6 and 2.8 mg thiamin hydrochloride/kg diet, respectively. Thiamin supplementation, however, did not change the liver pyruvate dehydrogenase activity and the proportion of pyruvate dehydrogenase in the active form. Disturbance of acid-base balance was postulated to be associated with the incidence of SDS. Other genetic, nutritional, and environmental factors are likely to modify the incidence by affecting the acid-base status of the chicken. / Graduation date: 1993

Most of the feed required for poultry production in the Republic of Yemen is imported from Europe. Sometimes, feed shipments arrive later due to lack of hard currencies to pay for the feed or to pay the freight charges. Yemeni broiler producers in such cases feed their birds a single feed ingredient or a mixture of ingredients until feed arrives. Five experiments were conducted to simulate feed shortage situations. As a single ingredient, barley is the grain of choice in case of feed shortages. When broilers were switched to corn-soy after the single ingredient diets, the compensatory growth was correlated with the severity of reduced growth. Feeding diets with a mixture of faba beans + sorghum grain with or without 7% herring meal for 21 and 49 days, respectively, reduced significantly (P<.05) mean body weight, total feed consumed, feed efficiency and apparent protein efficiency ratio. Feeding wheat bran at 10-15% with adjustment for protein and energy from day-old to 49 days of age resulted in significantly (P<.05) improved mean body weights compared to the control broilers. Increasing wheat bran levels further gradually reduced body weight and feed consumption. Abdominal fat increased significantly (P<.05) when wheat bran inclusion exceeded 20 percent. Cellulase supplementation did not show any significant interaction with wheat bran in all the measured parameters. Supplementing protease to wheat bran diets significantly (P<.05) reduced mean body weight, feed consumption and the feed conversion in broilers. These dramatic effects were proportionally ameliorated by increasing the levels of wheat bran. / Graduation date: 1991

Corrigenda inserted behind title page. Bibliography: leaves 275-306. The pattern of body growth and intestinal development of an Australian strain of broiler chicken, the Steggles x Ross (F1) in response to different diets was studied. Five experiments were designed to examine the pattern of growth and mechanisms involved. In four other experiments, the mechanisms underlying the gross response of the broiler chicks to dietary ingredients, anti-nutritive factors and growth enhancers were examined. Results indicated that a rapid development of the small intestine preceded significant overall body growth. Body growth would, however, depend more on the various physiological events such as those related to mucosal growth and renewal, digestive enzyme function, and nutrient transport. Some of the differences observed in productivity of broiler chickens on different diets were traced to events at the intestinal level.

No description available.

A series of experiments were carved out to study the effect of dietary enzyme inclusion or flaxseed processing on feeding value of flaxseed for broilers. The feed enzymes tested containing xylanase activities failed to produce any positive performance response when used in a 10% flaxseed diet with manufacturer recommended dosage for broilers (D 1 to 21). / Autoclaving of flaxseed at 16.5 kg/cm2 and 120°C for 15 min slightly improved the performance of young broilers fed a 10% flaxseed diet. This improvement was not observed at lower temperature and shorter period of autoclaving, but was magnified at higher flaxseed level. Autoclaving, microwave roasting, pelleting significantly (P < 0.05) reduced HCN content in flaxseed. The greatest HCN reduction was observed with repeated pelleting (54.9%) and microwave roasting (83.2%), from its 377 mg/kg of raw flaxseed. / When tested with roosters, flaxseed processing effectively increased ME values, dry matter, and ether extract utilization. The raw flaxseed TME and TMEn of 3343 and 3225 kcal/kg, respectively, was significantly (P < 0.01) increased by repeated pelleting (44%) and microwave roasting (32%). It was the result of significant improvement (P < 0.05) of EE utilization by the relevant processing. These improvements had a similar effect on total FA and linolenic acid utilization. / The processing method and flaxseed level had a very significant effect on deposition of total T-3 FAs in breast and thigh meat (P < 0.001) of 40 days old broilers. The highest level of T-3 FAs in muscle lipids of 23.04% and 26.46% for breast and thigh, respectively, was achieved with the highest flaxseed level (14% in days 1 to 21 days, and 17% in days 22--40) and pellet-then-mash processing, which lead to low T-6/T-3 ratios of 0.81 and 0.80 in breast and thigh muscle lipid, respectively. The proper flaxseed processing allowed more flaxseed (up to 12%) to be included in broiler diets without obvious growth depression, while achieving the higher desired T-3 FAs deposition in meat.

Corrigenda inserted behind title page. / Bibliography: leaves 275-306. / xxxv, 306 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The pattern of body growth and intestinal development of an Australian strain of broiler chicken, the Steggles x Ross (F1) in response to different diets was studied. Five experiments were designed to examine the pattern of growth and mechanisms involved. In four other experiments, the mechanisms underlying the gross response of the broiler chicks to dietary ingredients, anti-nutritive factors and growth enhancers were examined. Results indicated that a rapid development of the small intestine preceded significant overall body growth. Body growth would, however, depend more on the various physiological events such as those related to mucosal growth and renewal, digestive enzyme function, and nutrient transport. Some of the differences observed in productivity of broiler chickens on different diets were traced to events at the intestinal level. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, 1999

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