This programme of research uses choice test methodologies to quantify hungry broiler breeder chickens’ preferences for qualitative or quantitative dietary restriction. It begins with an outline of quantitative dietary restriction, its severity and welfare implications before discussing methods of qualitative feed restriction and the difficulties ascertaining whether it represents a welfare improvement. Chapter two reviews the factors affecting diet preferences and discusses implications for feed restricted broiler breeder diet preferences. Chapter three outlines the use of a closed economy T-maze task to quantity the diet preferences of feed restricted broiler breeders. It concludes that broiler breeders can learn a food versus no food task but find it very difficult to learn a task in which both of the options are rewarded with food and this impeded diet preference quantification. Chapter four demonstrates that severity of feed restriction underlies these difficulties in learning. In Chapter five, a conditioned place preference task to identify the effects of diets on affective state (hunger versus satiety) is reported. A method validation group demonstrated that broilers show a state dependent preference for an environment associated with ad libitum access to food. However, birds failed to show a preference between an environment associated with quantitative dietary restriction and one associated with qualitative dietary restriction. Chapter six applies state- dependent learning (SDL) to quantifying the satiating effects of quantitative and qualitative dietary restriction. However, a validation group suggested that SDL preferences were probably an artefact of the test rather than a genuine state-led preference. Finally, the overall conclusion that no evidence was found that broiler breeders want, or that their welfare is improved by, qualitative feed restriction was drawn. However, the conditions under which a preference was reliably observed and the presence of hunger – state dependent effects on learning and expression of learnt preferences complicates the interpretation of any findings. Recommendations for further research are highlighted.

Domestication in chickens has made feed-restriction a necessity if broiler breeder hens should reach sexual maturity and be fertile. This is claimed to cause chronic hunger. To measure hunger the gene expression of the appetite regulators agouti-related peptide (AgRP), pro-opiomelanocortin (POMC), neuropeptide Y (NPY) and adenosine monophosphate-activated protein kinase (AMPK) of the melanocortin system was quantified with qPCR. This was done in feed-restricted Red Junglefowl and compared with the gene expression of two strains of feed-restricted broilers, Ross 308 and Rowan Ranger, to detect possible effects on domestication on appetite regulation. POMC-expression was upregulated 2-fold in the feed-restricted Red Junglefowl. POMC-expression was downregulated by half in the feed-restricted Ross 308. AgRP/NPY-expression was upregulated 4-fold in feed-restricted Rowan Rangers. A comparison between the control groups (ad libitum fed) of the breeds showed that the NPY-expression was lower in Ross 308 and Rowan Ranger compared with the ancestor. Results show no difference in body weight of ad libitum fed and feed-restricted Red Junglefowl. Conclusions were that the feed-restricted Red Junglefowl was not properly restricted in food supply since no difference in body weight between the treatment groups was detected. The upregulation of POMC in the feed-restricted Red Junglefowl could be stress-linked influenced by the feeding type (scattering of food in litter). No conclusions of the impact of domestication on chicken’s appetite could be drawn. Domestication has probably had its impact by altering other signaling pathways of the melanocortin system than in the arcuate nucleus.

Feed restriction in the parental stock of meat producing chickens, broiler breeders, is essential in order to decrease the high growth rate that they are genetically selected for. The feed restriction does however lead to chronic hunger and stress. Stress can be measured by counting H/L ratios and the method of manually counting H/L ratios was evaluated. The method was not a good way to ensure reliable individual H/L ratios but still gives an H/L ratio indication on a group level and was therefore still used in the study. Two different feeding regimens were investigated in the study: 5:2 skip-a-day (SKIP) with two fasting days and daily feed restriction (CTRL), with chickens sampled at 9 and 12 weeks of age. There was no significant difference in body mass between the treatments at either age. SKIP chickens had significantly higher H/L ratios compared to CTRL at 12 weeks of age (P=0.020), but both treatments had H/L ratios above the reported limit of stress (0.5). The SKIP group on a feeding day significantly increased plasma glucose levels during the day (10.3 to 11.5 mmol/L, P=0.020) and had significantly higher liver mass and liver glycogen levels compared to the CTRL (P≤0.001). The SKIP group were also less fearful on fasting days and significantly less active than the CTRL (P≤0.050), regardless of age or daily feed differences. The conclusion was that both treatments were stressed but skip-a-day chickens were habituated to their regimen and did not experience worse welfare than daily fed broiler breeders.

A Organização Mundial da Saúde revela que mais de 20 milhões de crianças nascem com baixo peso ao nascimento em todo o mundo, sendo a má nutrição o principal fator desencadeante. Estudos realizados nas duas últimas décadas mostram que o status nutricional materno pode ser crítico no desenvolvimento de teratogenicidade; porém não há trabalhos que comprovem a associação entre restrição alimentar materna e a ocorrência de malformações. No entanto, o conceito de teratogênese não se restringe apenas às malformações estruturais logo após o nascimento, também são consideradas alterações funcionais, como aquelas comportamentais ou no sistema imune, entre outras, que podem se manifestar somente na maturação pós-natal. Assim, o presente trabalho visou verificar os efeitos da restrição alimentar materna durante a gestação, avaliando-a por meio tanto do protocolo clássico de teratogenicidade, como através de protocolos de imunoteratologia, analisando-se neste caso, as possíveis alterações no sistema imune da prole após o desmame e também na idade adulta. Foram empregadas ratas Wistar prenhes, divididas em cinco grupos iguais, um controle (CO) no qual os animais receberam ração ad libitum, e nos demais grupos, as fêmeas foram submetidas à restrição alimentar, do 6º ao 17º dia de gestação, diminuindo-se em 15 (E15), 40 (E40), 55 (E55) e 70% (E70) da quantidade de ração consumida pelos animais do grupo CO. Por meio do protocolo clássico de teratogenicidade, verificaram-se as possíveis alterações ósseas e viscerais sobre a prole. Empregou-se ainda o protocolo de imunoteratologia, no qual foram realizados testes nas proles tanto ao desmame como na idade adulta, e aferiu-se os seguintes parâmetros: hemograma, peso relativo do timo e do baço, celularidade do baço e da medula óssea; a imunidade inata: atividade de macrófagos peritoneais por meio da fagocitose, produção de peróxido de hidrogênio e óxido nítrico; a imunidade humoral: produção de anticorpos pelo ensaio do plaque forming cell e a titulação de anticorpos anti-eritrócitos de carneiro; e a imunidade celular: avaliação da hipersensibilidade tardia. Em relação às avaliações teratogênicas clássicas, estas mostraram haver, naqueles filhotes provenientes das ratas submetidas às restrições alimentares (E40, E55 e E70), diminuição no peso ao nascimento, aumento da proporção de fetos mortos até uma hora após o nascimento e aumento do número de fetos com ureter sinuoso; no entanto, não foi constatada a ocorrência de malformações graves, que pudessem colocar em risco a vida do concepto. Já as avaliações pós-natais revelaram diminuição no ganho de peso, do nascimento até a idade adulta, das proles provenientes das ratas do grupo E70. Em relação às alterações imunoteratogênicas, houve aumento no peso relativo do timo e da resposta imune celular nas proles destas mães submetidas à maior restrição alimentar, quando estes animais foram avaliados aos 21 dias de idade. Quando realizou-se este estudo nas proles com 70 dias (idade adulta), os filhotes provenientes de mães das diferentes restrições alimentares apresentaram aumento da resposta imune humoral; além disto aqueles filhotes de mães E70, mostraram aumento da resposta imune celular. Os dados apresentados na presente pesquisa permitem sugerir que a restrição alimentar em ratas Wistar durante a organogênese fetal, embora não promova malformações estruturais, produz prole de menor peso ao nascimento e é capaz de gerar alterações significantes no sistema imune dos filhotes. / The World Health Organization has reported that more than 20 million children worldwide are born with low birth weight, with malnutrition the main triggering factor. Studies in the past two decades have shown that maternal nutritional status may be critical in the development of teratogenicity, but there are no studies that directly relate maternal feed restriction and malformation. However, teratogenecity is not restricted only to structural abnormalities at birth, but may also include functional changes, such as behavioral or immune system alterations, among others, which may manifest themselves only in the postnatal period of maturation. Thus, this work aimed to assess the effects of maternal food restriction in pregnant rats using classical and immunoteratogenic protocols to evaluate the offspring. Thus, possible immune system changes were evaluated in the offspring after weaning and after maturation. Pregnant females were divided into five groups, a control group (CO) in which the animals received feed ad libitum, and four other groups, in which females were fed a restricted amount based on the total ingested by controls: 15% (E15), 40% (E40), 55% (E55) and 70% (E70) during days 6 to 17 of gestation. Rats were humanely euthanized and teratogenicity was evaluated using skeletal and visceral measurements. Immunoteratogenic effects were determined in weaned and mature offspring (10 weeks) using blood, thymus and spleen relative weights and spleen and bone marrow cellularity. In addition, innate immunity was determined using activity of peritoneal macrophages through phagocytosis, and production of hydrogen peroxide and nitric oxide. Humoral immunity was determined using production of antibodies by the plaque-forming cell assay and titers of anti-sheep red blood cells. Cellular immunity was determined by evaluating delayed type hypersensitivity. Traditional teratogenic indices showed that pups from females subjected to feed restriction (E40, E55 and E70) had a decrease in birth weight, an increased proportion of dead fetuses up to one hour after birth, and an increase in the number of fetuses with kinked ureter. No major malformations serious enough to threaten the life of the conceptus were observed. There was a postnatal decrease in weight gain in offspring from mothers of group E70 from birth to adulthood. There was also immune system changes, with an increase in the thymus relative weight (E40, E55, E70) and cellular immune response in offspring (21 days of age). When offspring were evaluated after maturation, those pups from mothers with feed restriction had increased humoral immune responses; in addition offspring from the E70 group showed an increase in cellular immune response. The data presented in this study suggest that feed restriction in Wistar rats during organogenesis does not promote structural malformations, but instead results in offspring with lower birth weights, and also promoted significant changes in the immune system of rat pups.

A Organização Mundial da Saúde revela que mais de 20 milhões de crianças nascem com baixo peso ao nascimento em todo o mundo, sendo a má nutrição o principal fator desencadeante. Estudos realizados nas duas últimas décadas mostram que o status nutricional materno pode ser crítico no desenvolvimento de teratogenicidade; porém não há trabalhos que comprovem a associação entre restrição alimentar materna e a ocorrência de malformações. No entanto, o conceito de teratogênese não se restringe apenas às malformações estruturais logo após o nascimento, também são consideradas alterações funcionais, como aquelas comportamentais ou no sistema imune, entre outras, que podem se manifestar somente na maturação pós-natal. Assim, o presente trabalho visou verificar os efeitos da restrição alimentar materna durante a gestação, avaliando-a por meio tanto do protocolo clássico de teratogenicidade, como através de protocolos de imunoteratologia, analisando-se neste caso, as possíveis alterações no sistema imune da prole após o desmame e também na idade adulta. Foram empregadas ratas Wistar prenhes, divididas em cinco grupos iguais, um controle (CO) no qual os animais receberam ração ad libitum, e nos demais grupos, as fêmeas foram submetidas à restrição alimentar, do 6º ao 17º dia de gestação, diminuindo-se em 15 (E15), 40 (E40), 55 (E55) e 70% (E70) da quantidade de ração consumida pelos animais do grupo CO. Por meio do protocolo clássico de teratogenicidade, verificaram-se as possíveis alterações ósseas e viscerais sobre a prole. Empregou-se ainda o protocolo de imunoteratologia, no qual foram realizados testes nas proles tanto ao desmame como na idade adulta, e aferiu-se os seguintes parâmetros: hemograma, peso relativo do timo e do baço, celularidade do baço e da medula óssea; a imunidade inata: atividade de macrófagos peritoneais por meio da fagocitose, produção de peróxido de hidrogênio e óxido nítrico; a imunidade humoral: produção de anticorpos pelo ensaio do plaque forming cell e a titulação de anticorpos anti-eritrócitos de carneiro; e a imunidade celular: avaliação da hipersensibilidade tardia. Em relação às avaliações teratogênicas clássicas, estas mostraram haver, naqueles filhotes provenientes das ratas submetidas às restrições alimentares (E40, E55 e E70), diminuição no peso ao nascimento, aumento da proporção de fetos mortos até uma hora após o nascimento e aumento do número de fetos com ureter sinuoso; no entanto, não foi constatada a ocorrência de malformações graves, que pudessem colocar em risco a vida do concepto. Já as avaliações pós-natais revelaram diminuição no ganho de peso, do nascimento até a idade adulta, das proles provenientes das ratas do grupo E70. Em relação às alterações imunoteratogênicas, houve aumento no peso relativo do timo e da resposta imune celular nas proles destas mães submetidas à maior restrição alimentar, quando estes animais foram avaliados aos 21 dias de idade. Quando realizou-se este estudo nas proles com 70 dias (idade adulta), os filhotes provenientes de mães das diferentes restrições alimentares apresentaram aumento da resposta imune humoral; além disto aqueles filhotes de mães E70, mostraram aumento da resposta imune celular. Os dados apresentados na presente pesquisa permitem sugerir que a restrição alimentar em ratas Wistar durante a organogênese fetal, embora não promova malformações estruturais, produz prole de menor peso ao nascimento e é capaz de gerar alterações significantes no sistema imune dos filhotes. / The World Health Organization has reported that more than 20 million children worldwide are born with low birth weight, with malnutrition the main triggering factor. Studies in the past two decades have shown that maternal nutritional status may be critical in the development of teratogenicity, but there are no studies that directly relate maternal feed restriction and malformation. However, teratogenecity is not restricted only to structural abnormalities at birth, but may also include functional changes, such as behavioral or immune system alterations, among others, which may manifest themselves only in the postnatal period of maturation. Thus, this work aimed to assess the effects of maternal food restriction in pregnant rats using classical and immunoteratogenic protocols to evaluate the offspring. Thus, possible immune system changes were evaluated in the offspring after weaning and after maturation. Pregnant females were divided into five groups, a control group (CO) in which the animals received feed ad libitum, and four other groups, in which females were fed a restricted amount based on the total ingested by controls: 15% (E15), 40% (E40), 55% (E55) and 70% (E70) during days 6 to 17 of gestation. Rats were humanely euthanized and teratogenicity was evaluated using skeletal and visceral measurements. Immunoteratogenic effects were determined in weaned and mature offspring (10 weeks) using blood, thymus and spleen relative weights and spleen and bone marrow cellularity. In addition, innate immunity was determined using activity of peritoneal macrophages through phagocytosis, and production of hydrogen peroxide and nitric oxide. Humoral immunity was determined using production of antibodies by the plaque-forming cell assay and titers of anti-sheep red blood cells. Cellular immunity was determined by evaluating delayed type hypersensitivity. Traditional teratogenic indices showed that pups from females subjected to feed restriction (E40, E55 and E70) had a decrease in birth weight, an increased proportion of dead fetuses up to one hour after birth, and an increase in the number of fetuses with kinked ureter. No major malformations serious enough to threaten the life of the conceptus were observed. There was a postnatal decrease in weight gain in offspring from mothers of group E70 from birth to adulthood. There was also immune system changes, with an increase in the thymus relative weight (E40, E55, E70) and cellular immune response in offspring (21 days of age). When offspring were evaluated after maturation, those pups from mothers with feed restriction had increased humoral immune responses; in addition offspring from the E70 group showed an increase in cellular immune response. The data presented in this study suggest that feed restriction in Wistar rats during organogenesis does not promote structural malformations, but instead results in offspring with lower birth weights, and also promoted significant changes in the immune system of rat pups.

Thesis (M.Sc) (Agriculture)--University of Limpopo,2007. / Two experiments were carried out to evaluate the effects of feed restriction during the starter stage and lysine supplementation during realimentation on productivity and carcass characteristics of Ross 308 broiler chickens. In the first experiment, the effects of level and period of feed restriction during the starter period on subsequent productivity were evaluated. A 2 (male and female chickens) x 3 (feeding levels, ad libitum and 75% and 50% of ad libitum) x 3 (restriction periods of 5, 7 and 9 days), factorial arrangement in a Completely Randomized Design was used. The effects interactions were not included in the results because earlier analyses including all the interactions showed that they were not important. Level and period of feed restriction during the starter stage had an effect (P<0.05) on live weight of the chickens at 21 days of age. However, female and male chickens had similar live weights at 21 days of age. Chickens on 75% ad libitum feeding attained complete live weight compensation at the age of 42 days. However, chickens on 50% ad libitum feeding did not ‘catch-up’ with those on ad libitum feeding. Differences due to the period of feed restriction during the starter stage were maintained up to the age of 42 days. Male chickens had higher (P<0.05) live weights at 42 days of age. Abdominal fat pad was not affected (P>0.05) by level and period of feed restriction and sex of chickens at 42 days of age. The second experiment evaluated the effects of feed restriction during the starter stage (14 to 21 days) and levels of lysine supplementation during realimentation (21 to 42 days) on productivity and carcass characteristics of male and female chickens. Feed v restriction affected (P<0.05) live weight of chickens at the age of 21 days and males were heavier (P<0.05) than females at the same age. Chickens on 75% ad libitum feeding attained complete compensation in live weight while those on 50% ad libitum feeding did not. Lysine supplementation during realimentation had no effects (P>0.05) on live weight and carcass characteristics of the chickens at 42 days of age. Male chickens attained higher (P<0.05) live weights than female chickens at 42 days of age. / National Research Foundation

The parental stock of meat type chickens (broiler breeders) are commonly feed restricted to decrease their rapid growth and the issues associated with it. Among these birds, chronic hunger and stress are the most prominent welfare concerns and mass heterogeneity within flocks a major management challenge. The present study compared small and large broiler breeders of the same age within a flock, with the hypothesis that small birds would show signs of poorer welfare indicated by higher corticosterone concentration and heterophil/lymphocyte ratio as a consequence of higher experienced feed restriction due to competition. It also aimed to characterize morphometric differences between small and large birds within flocks as well as between birds on different feeding regimens; skip-a-day vs. every-day-fed. Heterophil/lymphocyte ratio at 4 weeks was significantly higher in large birds compared to small birds, but corticosterone concentration did not differ. Relative mass of the upper gastrointestinal tract, pancreas and liver of small birds at 4 weeks of age were significantly larger, while relative muscle and gizzard fat mass were significantly lower compared to large birds. 12 weeks old skip-a-day fed birds largely followed the pattern of 4 weeks old small birds. In the present study, no clear signs of poorer welfare in small broiler breeders could be seen and the morphometric differences might suggest different ways to cope with feed competition. A larger gastrointestinal tract might indicate long-term investments and maybe that smaller broiler breeders, and skip-a-day fed birds, are better habituated to feed restriction.

There has long been evidence for increased lipids in the liver of chickens exposed to feed restriction, commonly used for production hens. Lipogenesis is an important part of the metabolism and storing of glucose, a source of energy. Few studies compare the difference of lipids in the liver in chickens between regular feed restriction and skip-a-day diets, despite differences in lipid content found in other organs and in overall carcass. In this study I experimentally investigate if a difference in lipid content can be found in broiler breeders exposed to two different feeding regimes, 65 % feed restriction and 5:2 skip-a-day, along with the difference between days and time points (a.m. and p.m.). I also experimentally investigate the effect on dry weights of the liver. I expected to see a difference in lipids of the liver, with an increase found in skip-a-day birds. However, a difference could only be observed in the dry weights of the livers in birds exposed to skip-a-day feeding. Although there was no significant change in lipids, there is a pattern for increase in lipids in skip-a-day birds. Therefore, the conclusion can be drawn that an increase in lipogenesis caused by skip-a-day diet exists but it was not big enough to cause a significant difference in lipid content. For the dry weights of the livers, we can suspect lipids and glycogen as the reason for the increased weight but to determine exactly how these two components affect the skip-a-day birds’ further inquiry is needed.

Large White turkey breeder hens were used to examine the effect of duration of feed restriction, prebreeder protein content, and nesting material on subsequent growth and reproductive performance. Day old poults were raised following standard commercial practices with feed and water for ad libitum consumption until 6 wk of age (WOA). At this time, hens were equally divided among six grower feeding regimens. The treatments were as follows: a) a control group fed standard commercial diets for ad libitum consumption (CON); b) a second control group like (a) but fed plain white oats from 19 through 26 wk (OATS). In contrast, the 4 remaining treatment groups were feed restricted beginning at 6 WOA to achieve body weights 45% less than the full-fed CON at 16 WOA. Birds were kept at this level of restriction until either 17.0 (R17.0), 18.3 (R18.3), 19.6 (R19.6), or 20.9 (R20.9) WOA. Thereafter, feed allowance was gradually increased to achieve a predetermined minimum target BW of 10.8 kg at photostimulation. An additional prebreeder protein treatment was superimposed from 27 to 31 WOA. Treatments reduced BW but none of the four quantitatively restricted groups achieved the target BW of 10.8 kg at photostimulation. Feed restriction reduced feed consumption and improved feed conversion. There were no differences in flock uniformity, sexual maturity, mortality, body composition at photostimulation, and total egg production. The R18.3 treatment achieved the highest peak production. The quantitative restriction treatments exhibited low laying persistency. There were no differences in number of large yellow follicles, egg weight, fertility, or hatchability, but poult weight was reduced in the R18.3 treatment. Dietary protein influenced the proportions of multiple follicle sets and percentage misshaped eggs.Three nesting materials were compared and were as follows: 1) all nests filled with shavings (S), 2) all nests filled with paper chips (P), and 3) two nests filled with shavings and two nests with paper chips (S/P). There were significant differences in percentage floor and broken eggs. Nesting materials did not affect total egg production, fertility, or hatchability. The data suggest, if restriction is too severe and is continued too near to the time of conventional photostimulation, BW recovery and egg production will be depressed. Oat feeding was the easiest treatment to implement and resulted in equivalent reproductive performance. Dietary protein content may affect proportions of multiple follicle sets. Turkey breeder hens can and do distinguish between nesting materials and this may affect floor laying. Combinations of various types of nesting materials within the same breeder unit should be avoided. (Key words: turkey breeder hens, feed restriction, prebreeder protein, egg production, body composition, nesting material) / Ph. D.

No description available.