Salmonella do grupo paratifóide é responsável por toxi-infecção alimentar no homem, veiculada por alimentos contaminados. Este estudo determinou o perfil genotípico de nove amostras de S. Typhimurium, a sua patogenicidade, assim como sua capacidade de colonização e invasão em aves SPF. Verificou-se pela análise dos genes: agfA, avrA, cdtB, fimA, fliC, invA, iroN, lpfC, mgtC, pefA, sefC, sifA, sipB, sipC, sitC, slyA, sopB, sopE1, sptP ou spvC em amostras de Salmonella Typhimurium que todas foram negativas para os genes sopE1 ou spvC. O gene cdtB estava presente em apenas uma amostra (11,11%) e o gene pefA em duas amostras (22,22%). O gene sefC foi encontrado em três amostras (33,33%). Em oito amostras (88,88%) os genes agfA, fimA, lpfC ou sptP estiveram presentes. Os genes avrA, fliC, invA, iroN, mgtC, sifA, sipB, sipC, sitC ou slyA ou sopB estiveram presentes em 100% das amostras analisadas. Determinou-se quatro perfis genotípicos. No ensaio de patogenicidade observou-se que as amostras inoculadas por via oral, não causaram mortalidade de pintinhos SPF de um dia de idade, com a exceção da amostra SA 633 e SA 006 que apresentaram 30 e 10%, respectivamente. No entanto, observou-se que a infecção por via subcutânea provocou uma maior mortalidade de pintinhos, sendo que as amostras SA 003, SA 004, SA 005 e a amostra vacinal mostraram somente 10% de mortalidade, a amostra SA 002 30%, as amostras SA 632 e SA 634 70% e a amostra SA 633 100%. A amostra SA 006 não provocou nenhuma mortalidade. A amostra mais patogênica pela via subcutânea foi a SA 633. O ensaio de colonização foi realizado em pintinhos SPF, com as amostras SA 002, SA 003, SA 004, SA 005, SA 006, SA 632, SA 633, SA 634 e amostra vacinal. Verificou-se ausência de invasão no fígado e baço 24 horas pós- infecção, exceto para as amostras SA 632 (30%) e amostra vacinal (20%). Após sete dias da infecção houve invasão em dois pintinhos com a amostra SA 002 e um pintinho com as amostras SA 004 e SA 005. Apenas na amostra SA 632 constatou-se colonização em ceco após 24 horas em 10% das amostras e após 7 dias em 70% pós-infecção. Concluiu-se que entre as amostras de Salmonella Typhimurium analisadas existiam diferentes perfis genotípicos baseando-se na presença ou ausência de genes de virulência, e que a amostra vacinal assemelha-se a amostras de S. Typhimurium estudadas quanto a presença dos genes. Os resultados do teste de patogenicidade das amostras de ST indicaram que a via de inoculação modifica a patogenicidade de uma mesma amostra e que a mortalidade após a inoculação pela via subcutânea é sempre superior que pela via oral. / Parathyphoid Salmonella are major food-borne pathogens spread by contaminated food products. This study determined the genotypic profile of nine samples of S. Typhimurium, pathogenicity, colonization and invasion in SPF chicks. It was found by analysis of genes: agfA, avrA, cdtB, fimA, fliC, invA, iroN, lpfC, mgtC, pefA, sefC, sifA, sipB, sipC, sitC, slyA, sopB, sopE1, sptP or spvC samples of S. Typhimurium all were negative to sopE1 or spvC. The cdtB gene was identified in one sample and pefA gene in two samples (22,22%). Sef C gene was detected in three samples (33,33%). In eight samples (88,88%) agfA, fimA, lpf or sptP were detected. AvrA, fliC, invA, iroN, mgtC, sifA, sipB, sipC, sitC, slyA and sopB were detected in all samples evaluated. Four genotypic profiles were established. Pathogenicity tests showed that samplesinoculated by oral gavage did not present mortality in one day old SPF chicks, except samples SA 633 and SA006 with 30 and 10%, respectively. However, it was observed that subcutaneous inoculation showed high mortality in SPF chicks than oral inoculation, and samples SA 003, SA004, SA005 and vaccinal strain showed 10% of mortality, 30% for sample SA002, 70% in the samples SA632 and SA 634 and 100% when the sample SA 633 was inoculated. No mortality was observed in sample SA006. Colonization test was performed in SPF chicks using the samples: SA002, SA 003, SA 004, SA005, SA006, SA 632, SA 633, SA 634 and vaccinal strain. The more pathogenic strain subcutaneously was the SA 633. There was not invasion in liver and spleen 24 hours p.i., except for sample SA 632 (30%) and vaccinal strain (20%). Seven days p.i. invasion was detected in two chicks inoculated with samples identified as SA 004 and SA 005. Sample SA 632 showed 10% of cecal colonization 24 hours p.i. and 70% after one week p.i. It was concluded that Salmonella Typhimurium strains including the vaccinal strain, showed different genotypical profiles, based on the presence or absence of genes of virulence genes. The results of the pathogenicity test indicated that inoculation route modify the pathogenicity of the same strain, and the mortality post-inoculation was always higher in chicks inoculated by subcutaneous route when compared to the oral route.

O objetivo deste trabalho foi avaliar a utilização da levedura hidrolisada como fonte de nucleotídeos para frangos de corte. As aves foram suplementadas com diferentes níveis de inclusão nas dietas iniciais de 1 a 14 dias de idade. Foram utilizados um total de 576 pintos da linhagem Ross 708, os quais foram distribuídos em 6 tratamentos com 8 repetições (12 aves por box). Os tratamentos consistiram da inclusão de 0, 2, 4, 6, 8 e 10 kg de levedura hidrolisada/tonelada de ração. A levedura hidrolisada foi adicionada na dieta no lugar do material inerte da ração. A dieta inicial foi fornecida na forma triturada enquanto as dietas de crescimento, final e de retirada foram fornecidas na forma de pellets. Durante todo o experimento o acesso à água e ração foi ad libitum. Todas as dietas foram feitas à base de milho, farelo de soja e gordura de frango e foram formuladas para atender as exigências nutricionais recomendadas pelo manual de recomendações nutricionais Ross 708. Aos 42 dias, as aves alimentadas com 1% de levedura hidrolisada tiveram maior peso corporal e ganho de peso quando comparadas aos demais tratamentos (P<0,05). Não houveram diferenças estatísticas entre os tratamentos para as variáveis mortalidade e densidade de vilos. Contudo aves que não foram suplementadas com levedura hidrolisada (tratamento controle) apresentaram menor profundidade de cripta e a suplementação de 1% de levedura resultou em maior altura de vilos. Aves as quais receberam dietas com 0,2% de inclusão de levedura hidrolisada apresentaram menor rendimento de peito que as aves que receberam os demais níveis de levedura, mas foram iguais as aves do tratamento controle. Contudo, o rendimento de carcaça, sassami e gordura abdominal não foram influenciados pelos tratamentos experimentais. Estes resultados demostraram a eficácia da utilização de levedura hidrolisada na dieta de frangos de corte no período de 1 a 14 dias sobre as características de produção. / The objective of this work was to evaluate hydrolyzed yeast utilization as nucleotides source to broilers. Birds were supplemented with different inclusion levels on starter diets from 1 to 14 days of age. A total of five hundred seventy six Ross 708 chicks were allotted to 6 experimental treatments with 8 replications (12 broilers per pen). Birds were randomly distributed in following treatments: 0, 2, 4, 6, 8 and 10 kg hydrolyzed yeast/ton of feed. Hydrolyzed yeast was added to the test diet in place of filler. Starter diets were supplied in crumbled form while grower, finisher, and withdrawal were supplied in pellet form. Throughout experiment water and feed were supplied ad libitum. All diets were based on corn, soybean meal and poultry fat, and were formulated to achieve nutritional requirements from recommendations guide for Ross x Ross 708 broilers. At 42 d chicks fed 1% hydrolyzed yeast demonstrated higher body weight and body weight gain over birds fed other treatments (P<0.05). Mortality and villous density did not differ among treatments. However birds fed control treatment showed lower crypt depth and 1% hydrolyzed yeast supplementation promoted higher villous high. Birds fed 0.2% hydrolyzed yeast showed lower breast meat yield than birds received other yeast levels, but were equals to control treatment control. However, carcass and tender yield, and abdominal fat were not influenced by treatments. These results indicated efficacy of hydrolyzed yeast utilization on broiler diets from 1 to 14 on production characteristics.

The objectives o-f this research were to investigate the effects of blending Canbra or Canola oil with other oils or fats on the nutritive value and autoxidative stability of the blended oils, and to investigate the possibility of using hydrolyzed oils (free fatty acids) in the study of fatty acid balancing. Canbra oil (containing 6.1% erucic acid) was blended with sunflower oil or animal lard 1/1 (w/w). Canola oil (0.55% erucic acid) was blended with sunflower oil in the ratios 9/1, 8/2, 7/3, 6/4 and 5/5. The nutritional value was assayed using growing chicks fed lipid at 3% in a practical diet during a 4 week feeding period. Evaluation was made using body weight, weight gain, feed consumption, feed conversion, feed digestibility, lipid digestibility, total fatty acid digestibility, metabolizable energy and individual fatty acid digestibility. Results show that Canbra oil is equivalent to animal lard but significantly inferior to sunflower oil. Blending Canbra oil and sunflower oil or animal lard improved chick growth and fatty acid utilization over that demonstrated by the Canbra oil alone. Canola oil was equivalent to sunflower oil and soybean oil in supporting chick growth. The 7/3 and 5/5 blends showed synergistic improvement in promoting growth, fatty acid, protein and metabolizable energy utilization. It was concluded that Canola oil is nutritionally equivalent to either sunflower oil or soybean oil and that blending with sun-flower oil further improved its nutritional value. Oil blending rendered no significant detrimental effects on stability. The fatty acids of hydrolyzed Canola and sunflower oil showed nutritive performance equivalent to that of the intact oils. The fatty acids of a hydrolyzed 5/5 blend of Canola oil and sunflower oil showed reduced absorption of some fatty acids and the fatty acids of hydrolyzed soybean oil showed reduced diet and fatty acid absorption relative to the intact oils. These results demonstrate that feeding hydrolyzed oils may be a useful method of investigating fatty acid balance but more research is required in this area. / Land and Food Systems, Faculty of / Graduate

The domestic chick (Gallus gallus domesticus) has been widely used as an animal model to investigate spatial orientation and the neural mechanisms underlying this function. In all vertebrate species the hippocampus plays an essential role in spatial orientation. Since the hippocampus is a bilateral structure, it is important to investigate the specific role of the left and the right hippocampi in spatial processing. Although, the domestic chick has been often used as animal model to assess cognitive lateralization, the involvement of the left and the right hippocampal formation in spatial orientation has been poorly investigated in this model. Behavioral studies using monocular eye occlusion have shown that in chicks the left eye-system (right hemisphere) is involved in the elaboration of spatial relational information, while the right eye-system (left hemisphere) processes local information. However, while visual lateralization in chicks had been traditionally considered to be induced by embryonic light exposure, recent studies suggest the presence of structural and behavioural asymmetries also in dark-incubated chicks. Thus, the main aim of this thesis was to test the lateralization of hippocampal functions in dark incubated chicks, both in spatial and non-spatial tasks. In the first study dark-incubated chicks were trained to orient in a large circular arena using spatial relational information provided by free-standing objects. Once chicks reached a learning criterion they were tested binocularly or under a monocular eye-occlusion condition. This study provided the first demonstration that domestic chicks are able to orient by relational spatial information provided by free-standing objects, in binocular vision conditions. However, if either one of the two eyes was occluded, chicks failed the orientation task. These results show that at least in dark-incubated chicks binocular integration is needed to solve this spatial orientation task. We also investigated if chicks have a preference to orient by local or spatial information provided by free-standing objects and if this ability is influenced by eye occlusion. Chicks preferred to use local over spatial cues to orient, both in binocular and monocular conditions (independently of which eye was occluded). These results indicate that local cues are processed by both eye-systems and do not require access to information from both eyes, contrary to relational spatial cues. Using the same setup, in the second study we directly investigated the involvement of chicks’ left and right hippocampal formation during orientation by free-standing objects. For this purpose we performed an immunohistochemical staining of the immediate early gene product c-Fos (a neural activity marker). Two independent groups of dark-incubated chicks were trained to find food in the large circular arena and the level of hippocampal activation was compared between the two groups. One group was trained to orient exclusively by local cues, while the other was orienting by spatial relational information provided by free-standing objects. This revealed selective activation of the right hippocampus during orientation by spatial relational information in dark-incubated chicks. While monocular occlusion has often been used to test lateralization of spatial functions in chicks, it is still unclear whether this manipulation affects hippocampal activation. The aim of the third study was to clarify this issue, by exposing dark-incubated chicks to a novel environment in conditions of monocular occlusion or binocular vision. Activation of the hippocampal formation was once again measured by c-Fos expression. Exposure to a novel environment is known to trigger hippocampal activation in different animals, including domestic chicks. As expected, exposure to the novel environment activated the hippocampus in binocular vision conditions. However, if either one of the eyes was occluded, the hippocampal c-Fos expression did not rise above what observed in the baseline condition (chicks maintained in a familiar environment). Thus, successful hippocampal response to a novel environment requires input from both eyes. Our results also suggest that monocular occlusion equally affects the left and the right hippocampus. Overall, access to information from both eyes plays a crucial role for the acquisition of a spatial map of a novel environment, in line with the behavioral results of the first study. Moreover, a task independent lateralization effect, with higher c-Fos expression in the left compared to the right hippocampus, could be observed in all the experimental conditions. This confirms the presence of neuroanatomical lateralization in dark-incubated chicks. The last study investigated whether chicks’ hippocampus would also respond to novel social stimuli, in line with the activation observed in this structure after exposure to a novel environment. Only few studies have directly investigated the involvement of birds’ hippocampal formation in social functions. Here, the hippocampal activation was compared between chicks exposed to an unfamiliar conspecific vs. chicks exposed to a familiar one. We found that the ventral and dorsomedial portion of the right hippocampus of dark-incubated chicks responds to an unfamiliar individual. This provides the first demonstration of hippocampal sensitivity to social novelty in birds. Overall the studies performed in this thesis indicate a selective lateralized involvement of domestic chicks’ hippocampal formation not only in spatial, but also in social functions.

No description available.

Understanding how appetite is regulated, via exogenous or endogenous factors, is essential to animal agriculture in order to maximize production capabilities, as well as in human medicine to generate ways to treat conditions such as eating disorders or obesity. The aim of this thesis was to evaluate the effects of ferulic acid (FA), an exogenous factor found within plant cells, and oxyntomodulin (OXM), an endogenous hormone generated in the gastrointestinal tract, on food intake in avian models, as well as elucidate the hypothalamic mechanisms responsible. In broiler chicks (Gallus gallus), FA administered peripherally (IP) resulted in a transient yet potent reduction of food intake. A behavior analysis revealed that FA-treated chicks defecated fewer times than control birds. Within the arcuate nucleus (ARC) there was an increase in c-Fos immunoreactivity, indicating neuronal activation, in FA-treated chicks. Within the hypothalamus, there was a decrease in mRNA abundance of galanin, ghrelin, melanocortin receptor 3, and pro-opiomelanocortin (POMC), however within the ARC there was a decrease in POMC and an increase in c-Fos mRNA after FA treatment. OXM, a proglucagon-derived peptide produced in the gastrointestinal tract, administered intracerebroventricularly (ICV) or IP in Japanese quail (Coturnix japonica), resulted in a decrease in food intake for 3 hours post-injection. There was an increase in c-Fos immunoreactivity within the ARC as well as the dorsomedial nucleus (DMN) in quail ICV injected with OXM. In conclusion, these novel data provide insights on the similarities and differences between factors that can affect appetite regulation via anorexigenic effects. / Master of Science / Exogenous and endogenous factors affect appetite regulation. Exogenous factors originate in feed components, additives, and other environmental factors that can affect bodily functions but are derived from an external source. Endogenous factors are made within the body, such as hormones and neurotransmitters, usually in response to a stimulus, and serve to communicate signals both locally and distantly in the body. Ferulic acid (FA), a natural exogenous factor originating within plant cells, is found in commonly consumed plant-based foods. When administered peripherally into broiler chicks (meat-type birds), FA caused a direct and potent, yet quickly diminishing, decrease in food intake via activation of cells within the hypothalamus, the region of the brain that is responsible for appetite regulation. Oxyntomodulin (OXM), an endogenous peptide hormone generated within the gastrointestinal tract in response to the digestion of nutrients, is known to decrease food intake in humans, rodents, and the broiler chick. However, its effects in Japanese quail, a model closer to a "wild-type" bird, are unknown. Quail injected peripherally (outside the brain) or intracerebroventricularly (ICV; into lateral ventricle of brain) with OXM showed a reduction in food intake that was more persistent than FA's effects with the effects also mediated via activation within the hypothalamus, although through slightly different molecular mechanisms. Understanding different factors that can regulate appetite in animals is necessary for agricultural applications to maximize production and improve health and welfare, as well as in humans to elucidate methods to treat appetite-related conditions, such as eating disorders and obesity.

see document / Master of Science

Each of 32 neonatal White Leghorn chicks (Gallus gallus domesticus) experienced each of the four environmental situations and motoric and vocal behaviors were observed. The four environments were derived from a 2 X 2 (stimulus availability X temperature) factorial design. The levels of stimulus availability were either present (visible) or absent (not visible) while the two temperature levels were 32.5°C or 18°C. A factor analysis of the observed behaviors yielded six factors; three of which concerned motoric behaviors and three of which concerned vocalizations. A 2 X 2 (stimulus availability X temperature) within subjects analysis of variance for each factor was also performed. These results show that motoric behavior was largely affected by the availability of the imprinted stimulus. Results from the vocalization factors revealed one factor comprised of twitter calls, a second factor comprised of peep calls and a third factor comprised of calls that sonographically resembled an intermediate call. The analysis of variance on these factors revealed that the situational occurrence of the intermediate call factor resembled neither of the other two, more traditional, vocalization categories. / Master of Science

Energy homeostasis is essential for survival across all vertebrate species and involves a multitude of physiological systems that are regulated by both central and peripheral neural signaling. The hypothalamus is responsible for integrating and processing these signals and thus is regarded as the regulatory center for balancing energy homeostasis. Eating disorders, such as compulsive eating behavior associated with obesity, and anorexia, are significant public health concerns worldwide. Thus, studying appetite regulation is necessary to provide novel information for the design of solutions for health concerns that stem from altered energy intake. Such information is also relevant for improving chicken health and productivity in an agricultural setting. The objective of this dissertation research was to determine the hypothalamic mechanisms underlying appetite regulation in birds. In Experiment 1, the Virginia lines of chickens were used to elucidate the mechanisms underlying stress-induced anorexia. These chickens have been selected for low (LWS) or high (HWS) body weight at 56 days of age and have different severities of anorexia and obesity, respectively. Chicks were subjected to a combination of thermal and nutritional stress after hatch and hypothalamic nuclei, including the lateral hypothalamus (LH), paraventricular nucleus (PVN), ventromedial hypothalamus (VMH), and arcuate nucleus (ARC), were collected 5 days later. Real-time PCR was used to measure the mRNA abundance of appetite-associated neuropeptides and receptors in each nucleus. The results showed that the two lines displayed distinct gene expression profiles in response to stress. In particular, the PVN of the LWS was significantly affected by stress, and expression of several anorexigenic factors was up-regulated including corticotropin-releasing factor (CRF), CRF receptor sub-types 1 and 2 (CRFR1 and CRFR2, respectively), melanocortin receptor 4, and urocortin 3, suggesting that stress-induced anorexia in the LWS may result from overriding anorexigenic signaling in the PVN, primarily through CRF signaling. This CRF signaling-associated hypothesis was further supported by results showing that the original phenotypes were restored when the LWS chicks were treated with astressin (CRF receptor antagonist) before exposure to stress. In Experiments 2 and 3, we attempted to determine the mechanisms of CRF's anorexigenic effect in chickens and Japanese quail. We administered CRF by intracerebroventricular (ICV) injection and the hypothalamus was collected 1 hour later for molecular analyses. Results showed that CRF exerted a similar inhibitory effect on food intake in these two bird species, however the hypothalamic mechanisms underlying this anorexigenic effect were different. ICV injection of CRF increased c-Fos expression in the PVN, VMH, dorsomedial nucleus (DMN), and ARC in chicks while it only affected the PVN and LH in quail. Hypothalamic gene expression results suggested that CRF decreased neuropeptide Y receptor sub-type 1 (NPYR1) in chicks while it increased proopiomelanocortin (POMC), MC4R, CRF, and CRFR2 in quail. These results suggested that the anorexigenic effect of CRF may involve a dampened neuropeptide Y (NPY) system in chicks whereas it is associated with activated CRF and melanocortin systems in quail. At the nucleus level in chicks, CRF injection decreased NPY system-associated gene expression (ARC and DMN) and increased CRF (ARC and PVN) and mesotocin (MT) (VMH)-associated mRNAs, suggesting that orexigenic signaling through NPY was overridden by the heightened anorexigenic tone through CRF and MT, which led to the inhibition of food intake. In Experiments 4 and 5, we used the same experimental design as for CRF studies to determine the hypothalamic mechanisms of the anorexigenic effects of neuropeptide K (NPK) and adrenomedullin (AM) in Japanese quail. Results from Experiment 4 showed that NPK injection activated the ARC and PVN, which was associated with increased mRNAs for a group of anorexigenic factors including CRF, UCN3, cocaine and amphetamine-regulated transcript (CART), and POMC, and decreased expression of several orexigenic factors, such as NPY and agouti-related peptide (AgRP). In Experiment 5, ICV injection of AM activated the ARC, the nucleus in which POMC and CART mRNAs were increased. In conclusion, these experiments revealed novel hypothalamic mechanisms underlying stress or exogenous neuropeptide-induced anorexia in birds and may provide insights on understanding appetite regulation from evolutionary, agricultural, and biomedical perspectives. / Ph. D. / Appetite regulation is important for survival across all vertebrate species and the hypothalamus is the regulatory center for control of feeding behavior. Thus, studying the functions of the hypothalamus on appetite regulation provide novel insight into the eating disorders, such as obesity and anorexia, a worldwide health issue. Also, such information is relevant for improving productivity in the modern chicken industry. The objective of this dissertation research was to determine the hypothalamic mechanisms underlying appetite regulation in birds. In Experiment 1, the Virginia lines of chickens were used to elucidate the mechanisms underlying stress-induced anorexia. These chickens have been selected for low (LWS) or high (HWS) body weight at 56 days of age and have different severities of anorexia and obesity, respectively. Chicks were subjected to a combination of thermal and nutritional stress after hatch. The results suggested the two lines displayed distinct appetite-associated gene expression profiles in response to stress in the hypothalamus. In particular, stress-induced anorexia in the LWS may result from potent feeding-inhibitory factor corticotropin-releasing factor (CRF). Thus, in Experiments 2 and 3, we attempted to determine the mechanisms of CRF's inhibitory effect on food intake in chickens and Japanese quail. We administered CRF by intracerebroventricular (ICV) injection and the hypothalamus was collected 1 hour later for molecular analyses. Results showed that CRF exerted a similar inhibitory effect on food intake in these two bird species. However, the inhibitory effect of CRF was primarily associated with a dampened neuropeptide Y (NPY) system which is a potent stimulatory factor for feeding behavior in chickens, whereas it may involve activated CRF and melanocortin systems in quail. In Experiments 4 and 5, we used the same experimental design as for CRF studies to determine the hypothalamic mechanisms of the inhibitory effects of neuropeptide K (NPK) and adrenomedullin (AM) in Japanese quail. Results from Experiment 4 showed that the feeding-inhibitory effect of NPK was associated with a group of increased feeding-inhibitory factors such as CRF and cocaine and amphetamine-regulated transcript (CART) and decreased feeding-stimulatory factors, such as NPY and agouti-related peptide (AgRP) in the hypothalamus. In Experiment 5, AM increased gene expression of CART and proopiomelanocortin (POMC). Overall, these experiments suggested the roles of the hypothalamus in stress or exogenous neuropeptide-induced anorexia in birds and may provide insights on understanding appetite regulation from evolutionary, agricultural, and biomedical perspectives.

The aim of this study was to evaluate the effects of broiler maternal dietary lysine intake on progeny performance. Three experiments were conducted with chicks hatched from Cobb 500 breeders at 38, 48, and 60 weeks of age. Breeder hens received six dietary treatments (T1-T6) from 26 to 60 weeks of age, which allowed an intake of 800, 930, 1070, and 1200 mg lysine/bird/d (T1-T4) respectively. An intake of 800 mg/bird/d at 26 weeks was increased by 25 mg every two weeks to provide 1225 mg lysine/bird/d at 60 weeks (T5). An intake of 1200 mg/bird/d at 26 weeks was reduced by 25 mg every two weeks to supply 775 mg lysine/bird/d at 60 weeks (T6). A total of 320, 401, and 390 chicks were hatched from breeder hens at 38, 48, and 60 weeks of age respectively. Immediately after hatching, 270, 384, and 384 unsexed chicks from breeder hens at 38, 48 and 60 weeks of age respectively, were placed in an environmentally controlled room and randomly allocated (within a treatment) to single-tier cages (80 × 50 cm). Nine chicks from breeders at 38 weeks of age and 8 chicks from breeders at 48 and 60 weeks of age were placed in each pen, keeping chicks from the same treatment group together for 21 d. Chicks were fed ad libitum with a commercial broiler starter crumble for 21 d and water was provided ad libitum throughout the duration of each trial. Feed intakes (FI), body weight gain (BWG) and feed conversion ratio (FCR) were measured weekly. Data were subjected to analysis of variance using a generalized linear model of GenStat 12th edition. Simple linear regression model of GenStat 12th edition was used where appropriate. Significant improvements in offspring feed intake and body weight gain from 7-21 d were observed in chicks hatched from young breeder flocks (38 weeks) with low dietary lysine intakes (800, 930 and 950 mg/bird/d). The effect of maternal dietary lysine intake on offspring performance disappeared with the aging of the breeder flock (60 weeks). It was concluded that lower maternal dietary lysine intakes (800, 930 and 950 mg/bird/d) may improve feed intake and body weight gain from 7-21 d of broiler chicks hatched from younger breeder flocks (38 weeks). / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.