During pregnancy, body fat stores increase in part to subsidize the high energy cost of lactation. One effect of exercise, on the other hand, is to lower percent body fat. The effect of exercise during pregnancy and lactation on body fat, and on body composition in general, is not well documented. There is also a paucity of data on the effect of exercise during these physiological states on food intake and body weight. If exercise during pregnancy decreases body fat stores, would lactation performance subsequently be compromised? This study was designed to determine the effect of moderately strenuous aerobic exercise, during rat pregnancy and lactation, on food intake, body weight, body composition and lactation performance. Virgin female Sprague-Dawley rats were divided into exercised (n=40) and sedentary (n=40) groups. Exercising rats were trained over three weeks to run on a treadmill at 30 m/min, 2 hours/day, 5 days/week. Within each group, two subgroups were then mated and three subgroups remained as virgin age controls (n=8 per subgroup). Of the mated subgroups, one was terminated within 24 hours of parturition and the other on day 14 of lactation. Subgroups of virgin sedentary and exercising controls were terminated at times corresponding to each of mating, parturition and day 14 of lactation of mated animals. Carcasses were assayed for fat, water, ash and protein. Ad libitum food intake and body weight were monitored throughout the study, as was the weight gain of pups of lactating dams. MANOVA showed the effect of activity to be significant on food intake at week three of training and during the pregnancy period (p<0.00l) and at week one (p<0.0l) and two (p<0.05) of lactation. The effect of activity was highly significant (p<0.00l) on body weight from week three of training and throughout the pregnancy and lactation periods, as well as on the percent fat, water and ash of the rat carcasses. Post hoc multimean comparisons (Scheffe) at the p<0.05 level revealed that exercise resulted in a significant increase in the food intake of virgin rats, and nonsignificant increases in the food intake of pregnant and lactating rats. Body weights of virgin, pregnant and lactating exercising rats were significantly greater than their respective sedentary controls. Despite their heavier body weights and greater food intake, the estimated carcass energy content of exercising animals was lower than that of sedentary animals. This finding was reflected in the carcass composition whereby exercising rats, whether virgin, pregnant or lactating, contained consistently less fat and more water than sedentary controls. At parturition, pregnant animals contained significantly less fat, more water and more ash than sedentary pregnant controls. After 14 days of lactation, there were no significant differences in carcass composition between exercising and sedentary dams. However, lactating rats, whether exercising or sedentary, catabolized approximately 50 percent of the body fat present at parturition. Pup weight gains were not significantly different between exercising and sedentary dams. From these findings it was concluded that the effect of exercise during pregnancy and lactation on food intake, body weight and body composition was comparable to its effect in non-gravid rats. Moderately strenuous exercise during pregnancy prevented the increase in body fat deposition normally present at this time. Despite these depleted fat stores, the energy supplied by the mobilization of the remaining fat and the increase in food intake was adequate to support normal pup growth. / Land and Food Systems, Faculty of / Graduate

In a Holstein herd (125 cows) the influence of early and late breeding post partum on reproduction and production was investigated. At calving the cows were randomly assigned to two groups. The early bred group was scheduled to be bred at the first visible heat following 50 days post partum which resulted in an average interval of 73 ± 18 days from parturition to the first service. The average interval from parturition to conception was 88 ± 33 days. The cows in the early bred group conceived after an average of 1.50 (range: 1 to 3) services per conception. The late bred group was scheduled to be bred at the first visible heat following 80 days post partum which resulted in an average interval of 93 ± 17 days from parturition to the first service. The average interval from parturition to conception was 120 ± 40 days. The cows in the late bred group conceived after an average of 1.96 (range: 1 to 5) services per conception. The number of services per conception was significantly (P£.05) higher for the late bred group. The early post partum reproductive activity was monitored with milk progesterone analyses. A sample of milk strippings was analysed by a radioimmunoassay technique every second day from 6 days post partum until conception occurred or the animal was removed from the herd. Cows which did not conceive were excluded from the statistical analyses. The average length of the first estrous cycle was 17 ± 7.5 days. The first progesterone detected heat occurred 33 ± 10 days post partum compared to the first visible heat which occurred 48 ± 26 days post partum. Calving associated problems and the calving during the pasture season delayed conception in the late bred group but not in the early bred group. The late bred group produced more fat corrected milk (FCM) in the 305 day lactation and in the first 150 days of the subsequent lactation and also gained more (P≤.05) weight between calvings. Cows calving during the pasture season produced more FCM in the 305 day lactation but gained significantly (P≤.01) less weight between calvings than cows calving in the non-pasture season. There was no difference between early and late bred group, health status groups or groups according to the calving season in terms of average daily milk and FCM yield calculated over the entire period of this experiment (beginning of current lactation to day 150 of the subsequent lactation, including the dry period). Calving difficulties and early post partum reproductive problems were not related to production traits. / Land and Food Systems, Faculty of / Graduate

A glutamina (Gln) e o glutamato (Glu) participam ativamente do metabolismo, sendo fontes de energia para células de intensa proliferação, como enterócitos, células do sistema imune, trofloblastos e embriões. O objetivo geral foi avaliar os efeitos da suplementação de Lglutamina e L-ácido glutâmico (1%) nas dietas: (a) marrãs desde a chegada ao local de experimentação até a manifestação do primeiro estro, seguido do primeiro ciclo estral e flushing (capítulo I), (b) primíparas no terço final da primeira gestação, seguida da lactação, intervalo desmame estro e terços inicial e médio até 73 dias da gestação subsequente (capítulo II); e nas dietas de leitões do desmame aos 49 dias de idade (capítulo III). No capítulo I, as fêmeas suplementadas durante o flushing, foram abatidas aos 5 dias de gestação para avaliação dos embriões e ovário. O número de corpos lúteos do grupo suplementado foi superior numericamente ao grupo controle (20,25 versus 17,88, respectivamente), sugerindo possível efeito da suplementação na taxa de ovulação, acompanhado do maior percentual de células vivas e menor de células mortas, com significância nas variâncias, indicativas de menor variabilidade e melhor homogeneidade das estruturas, levando a possível influência na viabilidade embrionária. No capítulo II, os pesos corporais e as espessuras de toucinho (ET) das primíparas não revelaram diferenças significativas nos períodos analisados. As concentrações de glutamina e glutamato no plasma sanguíneo foram significativas para o tratamento (p<0,05) até o parto, revelando concentrações maiores para as fêmeas suplementadas. Destacou-se diferença significativa na sobrevivência dos leitões no aleitamento em favor do grupo suplementado. Aos 73,45 ± 1,61 dias da segunda gestação, o peso dos fetos do grupo suplementado (p=0,0690) foi maior em relação aos do grupo controle. Os leitões desmamados (Capítulo III) foram avaliados em arranjo fatorial 2x2, sendo um fator a suplementação da mãe e outro a suplementação dos leitões. O peso ao desmame foi significativo para o fator Mãe, destacando maiores pesos para os leitões oriundos de mães controles (p=0,0296), contudo de 21 a 34 dias de idade, a conversão alimentar foi melhor para os leitões oriundos de mães suplementadas (p=0,0522). Ao final da terminação (133 dias de idade), os tratamentos não mostraram diferenças significativas em relação ao desempenho. Considerando que o peso dos leitões de mães controles iniciou superior ao desmame, os grupos se igualaram em relação ao peso final. Os resultados trazem novas perspectivas para futuras pesquisas em relação ao uso da suplementação de L-glutamina e L-ácido glutâmico, principalmente no flushing, nos terços inicial e médio da gestação, pois, pode influir positivamente na taxa de ovulação e desenvolvimento homogêneo e maior peso dos fetos. Além disso, a ação no desenvolvimento dos leitões, sobrevivência no aleitamento e quanto à integridade intestinal no período pós desmame também merecem atenção, o que pode contribuir, na abordagem interativa dos parâmetros, influência positiva na economia da produção. / Glutamine (Gln) and glutamate (Glu) actively participate in metabolism as energy sources for intense cells proliferation, such as enterocytes, immune cells, and embryos trophoblasts. The main objective was to evaluate the effects of L-glutamine and L-glutamic acid (1%) supplementation in the diets: (a) sows since arrival to the experimental place until the appearing of the first heat, followed by the first estrous cycle and flushing (chapter I), (b) gilts at the end of the first third of pregnancy, then lactation, weaning estrus interval and initial and middle thirds of up to 73 days of gestation subsequent (Chapter II); and in weaning diets of piglets at 49 days of age (Chapter III). In Chapter I, the females supplemented during the flushing were slaughtered at the 5th gestation day for embryos and ovary evaluation. The number of corpora lutea in the supplemented group was numerically higher than in the control group (20.25 vs. 17.88, respectively), suggesting a possible effect of supplementation on ovulation rate, accompanied by the highest percentage of live cells and smaller percentage of dead cells with significance on variances, which are indicative of lower variability and better structures homogeneity, leading to possible influence on embryo viability. In Chapter II, primiparous revealed no significant differences in the weights backfat thickness at the end of gestation, lactation and subsequent pregnancy. The glutamine and glutamate concentrations in blood plasma were significant for the treatment (p <0.05) until delivery, showing higher concentrations for supplemented females. Noteworthy the significant difference in the piglets survival during lactation in favor of the supplemented group. At 73.45 ± 1.61 days of the second pregnancy, the fetal weights in the supplemented group (p = 0.0690) was higher compared to the control groupy. Weaned piglets (Chapter III) were evaluated in a 2x2 factorial arrangement, with mother supplementation and piglets supplementation as factors. The weaning weight was significant for the control group, regardless of mothers supplementation (p = 0.0296), however, from 21 to 34 days of age, feed conversion was better for piglets from supplemented mothers (p = 0, 0522). By the end of termination (133 days of age), the treatments did not show significant differences, considering that the weight of controls piglets was heavier at weaning, the animals were equal with respect to final weight. The results open new perspectives for future research regarding the use of L-glutamine and L-glutamic acid supplementation, especially in flushing, in the early and middle thirds of pregnancy, since it can have a positively influence in ovulation rate, homogeneous development and greater fetues weight. Moreover, its effect on piglets development, both in the survival during lactation aspect, as to gut integrity in the post weaning period, also deserve attention, since the interactive approach can provide additives in the production economy.

MSCPNT / Department of Nutrition / Introduction: Iodine is an essential nutrient required by humans for the synthesis of thyroid hormones, which are vital for normal growth and development. Objective: The primary aim of the study was to describe the iodine status of lactating mothers and infants aged from 0 to 6 months in the Vhembe and Mopani Districts. Methods: A cross-sectional study conducted on 246 infant-mother pair, from the Mopani and the Vhembe Districts. Data was gathered using a questionnaire. Breastmilk, mother urine, infant urine, household salt and drinking water were collected to be analysed for iodine content. Results: The median of breastmilk iodine concentration level amongst lactating mothers in the Vhembe District was 101.4 µg/l (IQR 62.9 – 175.1 µg/l) and 154.4 µg/l (IQR 92.6 – 211.8 µg/L) in Mopani. The median UIC of mothers in Vhembe was 98.5 (IQR 57.66 – 153.93), whereas in the Mopani District the median UIC of mothers was 126.08 µg/l (IQR 69.89 – 206.71 µg/L). The median UIC of infants in Vhembe was 220 (IQR 106.67 – 418.43 µg/l) and in the Mopani District was 321.94 µg/l (IQR 167.96 – 482.66 µg/l). Conclusion: The BMIC in the study signifies iodine sufficiency in both the Vhembe and the Mopani Districts. The results of this study suggest that the BMIC be included in studies assessing iodine status in lactating mothers since the UIC only reflects iodine that was consumed recently. The UIC may under estimate the maternal iodine status if it is not complemented by the BMIC data. / NRF

The aim of this thesis was to evaluate changes in resting energy expenditure (REE) in ten lactating women between three weeks and nine months postpartum to find out whether there is any link with the parameters presented in this study. Measurements were taken at four intervals. At three weeks and at three, six and nine months postpartum. They were taken in the morning after a night fast (12 hours) and used indirect calorimetry with a canopy in awake lying subjects for approximately 25 minutes. The room was shaded with minimal noise with a temperature around 20 řC. Urine was collected over 24 hours and was examined for nitrogen concentration. The median REE was 1591,86 kcal/day at 3 weeks postpartum, 1398,08 kcal/day at 3 months, 1401,78 kcal/day at 6 months and 1455,03 kcal/day at 9 months postpartum. Values of REE per kilogram of body weight are 21,8 ± 0,36 kcal/kg and are consistent throughout the measurement period. The oxidation of lipids was dominant compared to other substrates and the lowest was oxidation of sacharides during the whole observation period. Correlations were found in parameters such as, body weight and REE per kilogram, breast milk and respiratory quotient (RQ), length of gravidity with RQ/ volume of exhaled carboxydioxide/ volume of inhaled oxygen. Another was between protein...