Introduction : Family Poultry (FP) are birds of indigenous breeds living in almost symbiotic relationship with human communities. The chickens are usually free ranging, or have very limited restrains on their access to the village environment. African livestock population statistics for 1995 indicates poultry to be the most numerous species of farm animal (Anonymous, 1996a). More than 80% of poultry are kept in rural areas and contribute substantially to annual egg and meat production (Sonaiya, 1997). Throughout Africa poultry production stems from ancient traditional practices. FP is the most important type of poultry kept on the continent. In general, village producers keep small flocks of between 5 and 20 birds per household (Gueye, 1997a). Women and children play a key role in their management (Kitalyi, 1996). Because of its productivity, FP production has been neglected and is frequently considered by farmers as an insignificant occupation compared with other agricultural activities. Nevertheless, outside urban centers and especially in non-coastal areas, FP provides the population with a vital source of protein and income. In addition, they play an important role within the context of many social and/ or religious ceremonies. Although this type of poultry constitutes an important part of food security for rural households in South Africa, scientists have not explored this area of research for improving or recording this production system. Yet, FP survived for decades without being wiped out, in the interim, their keepers have gathered and stored a wealth of knowledge and experience, ensuring the survival of this genetic resource. The objective of this study was to collect the baseline data on FP production systems, determine their production constraints and achieve data for future use in the intervention strategies.

The purpose of the study was to develop a realistic method of determining the optimum replacement time of steers in a feedlot in which there are sequential feeding cycles. There are two models for steers developed and discussed in this paper. The first model optimizes the length of stay in the feedlot assuming that feedlot capacity is the limiting constraint. The second model optimizes the length of stay in the feedlot when working capital is the limiting constraint. A third model is developed to determine the optimum length of feeding time for market hogs in a feeding barn. An evaluation of each model is made. It is concluded that the cattle models have a limited use because of the high variability in performance. The hog replacement model is quite valid and can be used in a modern hog feeding enterprise. / Land and Food Systems, Faculty of / Graduate

The present investigation was conducted to determine the effect of an infection with Eimeria acervulina on vitamin A deficient birds. One hundred day-old chicks were divided into 2 equal groups, and one group was raised on 440 I.U. vitamin A per kilogram of feed, while the second group received the normally recommended 4400 I.U. per kilogram. At 5 weeks of age, half the birds from each group were given an immunizing infection with 3 million oocysts of E. acervulina. The clinical symptoms were more acute, and the oocyst production, mortality, and weight losses significantly higher, in the birds on the low vitamin A diet. When the birds were 9 weeks old, half were subjected to a second infection and the other half held until they were 19 weeks old. The 9-week-old birds were given an oral inoculation of 10 million oocysts to evaluate the effect of a low vitamin A diet on: the strength of the immune response; a primary infection with E. acervulina in 9-week-old birds; and the early tissue stages of the parasite in immune and non-immune birds. The results from this experiment showed that the degree of immunity is not affected by a low vitamin A ration, but primarily determined by the severity of the initial infection; and that the primary infection in 9-week-old chicks is clinically very similar to that in younger birds. The histological examinations demonstrated that the low vitamin A level used in this study did not affect the integrity of the intestinal epithelium, nor the development of the endogenous forms of the parasite. It was also shown that the sporozoite invasion was the same in immune and non-immune birds, but the schizont development was severely inhibited in the immune birds regardless of the vitamin A level. The non-immune birds on the low vitamin A ration did not show as distinct a heterophil response to infection as did the other groups. The remaining birds, half which were immunized, were maintained on their respective diets until 19 weeks of age, and during this period there was no clinical evidence of a vitamin A deficiency, and the growth rate was not significantly affected by the level of vitamin A in the diet. When 19 weeks old, the birds were inoculated with 25 million oocysts of E. acervulina to assess the effect of an extremely heavy primary infection in older birds, and to evaluate the degree of immunity still retained 14 weeks after an initial infection. The mortality was very high, and the weight losses significantly greater, in birds on the low vitamin A dietary level. Immunity, although decreased from the earlier experiment, was still present in birds on both levels of vitamin A. / Land and Food Systems, Faculty of / Graduate

In view of the importance of alanine as a gluconeogenic precursor in ruminants, the objective of the present study was to assess the effectiveness of three techniques in estimating the metabolic parameters surrounding alanine in wethers fed a maintenance diet of alfalfa hay. A preliminary experiment utilized a blood flow technique to study the net production and/or utilization of both alanine and glucose by the portal drained viscera. Such a method involved evaluating the arterio-venous concentration differences of alanine and glucose, in conjunction with determining the rate of portal vein blood flow. Radioactively labelled ¹⁴C - alanine was administered as a single injection in the second series of experiments to estimate the metabolic parameters of alanine as well as its contribution to glucose synthesis. The L-U-¹⁴C-alanine was given intravenously through previously implanted jugular catheters and the fall in the specific activity of plasma alanine with time was determined. The line of best fit for the decay curve of the specific activity of plasma alanine was constructed by means of a computer using a multi-term exponential function which enables the estimation of such parameters as the pool size, space, total entry rate, irreversible loss and recycling of alanine. The per cent conversion of alanine to glucose was determined by the corresponding peak of glucose specific activity following the single injection of ¹⁴C - alanine. The turnover of alanine was also studied using a continuous infusion of L-U-¹⁴C-alanine without a priming injection. The specific activity of plasma alanine reached a plateau five hours after the beginning of the infusion. It was from these plateau levels that the rate of irreversible loss of alanine as well as its percent conversion to glucose was estimated. The results indicated that the single injection technique was able to partition the total entry rate of alanine into irreversible loss and recycling and thus prove more informative than a continuous infusion method. The present study also suggested that under certain physiological stress conditions in ruminants, where recycling becomes prominent, a continuous infusion approach may overestimate the actual rate of irreversible loss of alanine. / Land and Food Systems, Faculty of / Graduate

Soybean meal-protected tallow has been commercially available in Canada for use in dairy rations, since 1975. The reported effects of feeding protected tallow to dairy cows have been variable and the prices of protected tallow supplements have been high. In view of the lower cost of canola meal relative to soybean meal in Canada, a study was undertaken to investigate the efficacy of feeding protected tallow made either from soybean meal or canola meal, to dairy cows in early lactation. Secondly, a comparison was made between the soybean meal-protected tallow and the canola meal-protected tallow. Twenty-seven cows from the University herd, comprised of 12 first-calf Holstein heifers, 3 Holsteins in their >2nd lactation, 4 Ayrshire heifers and 8 ≥2nd lactation Ayrshires, were used in a continuous feeding trial which was conducted from day of calving until the end of week 20 of lactation. Cows were randomly assigned within breed and lactation category (9 cows per treatment) to one of 3 isonitrogenous (16 % crude protein) concentrates: a) no protected tallow (control); b) 8 % soybean meal-protected tallow; or c) 8 % canola meal-protected tallow, which they received during weeks 1-15 (inclusive). From the beginning of week 16 until the end of week 20 all cows were fed a 16 % crude protein, post-treatment concentrate (no protected tallow). Throughout the 20-week trial the ratio of concentrates to cubes offered was maintained at 70:30 with feed intakes being ad libitum. Between weeks 13 and 16, 4 cows per treatment were assigned to a digestibility trial involving a 7-day total Collection of faeces and urine. Protected tallow rations produced significant increases over the control ration (P<.05) in the yields of milk, 4 % fat-corrected milk and milk fat, and protected tallow rations increased the efficiencies of conversion of gross energy, digestible energy, crude protein and digestible protein to milk, 4 % fat-corrected milk, solids-corrected milk and milk energy (P<.05). The apparent digestibility of ether extract and the concentration of plasma non-esterified fatty acids were significantly higher on rations with protected tallow (P<.05). Milk protein % was significantly reduced below the control level with rations containing protected tallow and rumen acetate and the acetate:propionate levels were also decreased. Protected tallow rations had no significant effect on the intakes of dry matter, gross energy, digestible energy, crude protein or digestible protein or on the apparent digestibilities of dry matter, organic matter, gross energy, nitrogen, acid-detergent fibre, ash, calcium, phosphorus or magnesium (P>.05). Also the yields of solids-corrected milk, milk gross energy and milk protein, the plasma glucose concentration and average daily gain were not significantly different, on rations containing protected tallow, compared with the control ration. There was no significant difference between the soybean meal-protected tallow ration and the canola meal-protected tallow ration for any parameter measured except apparent digestibility of ether extract which was significantly higher for the canola meal-protected tallow ration (P<.01). / Land and Food Systems, Faculty of / Graduate

This diploma thesis is focused on current problematics of monitoring of selected mycotoxins, DON and ZEA, in feeds in Czech Republic. The objective of my thesis was to elaborate a literature search from available books, electronic and periodical sources and service materials. Literature search is aimed at overall overview of mycotoxins, describes their characteristics, biological effects, methods of detection as well as summarizes recent legislation requirements concerning occurrence of these substances in feeds for animals. The aim of experimental part was a determination of selected mycotoxins in feed (DON and ZEA) by ELISA method and their evaluation according to the maximum limits. The diploma thesis was prepared in diagnostic laboratory SEVARON, s. r. o. in Brno.

As an indicator of above ground net primary productivity, the Normalised Difference Vegetation Index (NDVI) has been identified as important tool in understanding the resource requirements and distribution patterns of large herbivores. The efficacy of NDVI as an ecological tool is however, strongly contingent upon the scale of the foraging hierarchy at which data are interpreted. In this study I investigated whether vegetation greenness, as represented by MODIS NDVI 250 m resolution imagery, is a driver of zebra (Equus quagga) foraging patterns at three spatial/temporal scales, namely location within sixteen day home ranges, sixteen day home range within seasonal home range and seasonal home range within total home range, during both wet and dry periods. I also investigated how tree canopy cover influences the ability of MODIS NDVI to see the greenness at which zebra respond. During the wet season, the zebra clearly demonstrated evidence of selecting for greenness and a tendency to avoid areas of high woody canopy at all three scales. Conversely, during the dry season the zebra showed no preference for greenness and no consistent preference for or against woody cover across the three scales. I also noted that despite a positive relationship between ΔNDVI and woody canopy cover, the relationship is not significant and suggests that in savanna ecosystems tree densities may not be high enough to affect overall MODIS NDVI readings. These results indicate that zebra foraging behaviour is complex and differs according to the scale of analysis, season, and even between individual zebra herds. The ability of MODIS NDVI to elucidate zebra movements is therefore limited to specific spatial and temporal scales and should be accompanied by an understanding of non-forage related factors.

No description available.

No description available.

No description available.