Coccidiosis has a negative economic impact on the commercial poultry industry, and probiotics are beneficial bacteria that aid in maintaining healthy gut microflora. We hypothesized that probiotic administration would positively affect gut morphology and increase IgG secretion during an Eimeria challenge, which was evaluated by measuring total chicken IgG and gut morphology (villus height, villus width, villus surface area, crypt depth, villus height to crypt depth ratio and lamina propria thickness). On day-of-hatch, broilers were placed into floor pens with 50 percent pine shavings and 50 percent used litter. The broilers were exposed to Eimeria oocysts via the feed on day 14 and challenged on day 36. On days 6, 22, 36, and 43, tissue samples from the intestine were collected for morphological evaluation, and blood samples were taken to quantify chicken IgG from serum. Data were measured using a factorial ANOVA and main effect means were deemed significant at P ≤ 0.05. In cases where significant interactions were observed, data was subjected to a one-way ANOVA. All means were separated using a Duncan’s Multiple Range Test. On day 6 in the duodenum, a significant interaction was observed regarding vaccination and probiotic administration (Coccivac®-B, Intervet/Schlering-Plough Animal Health/Merck and Co., Inc., Whitehouse Station, NJ). Villus height to crypt depth ratio decreased in ionophore treated birds compared to control birds in the duodenum and lower ileum on day 6, 36, and 43. Villus crypt depth in vaccinated birds decreased in the duodenum after the challenge. On day 43, the ionophore treated birds had less villus height and surface area compared to control and vaccinated birds, while lamina propria thickness increased in the duodenum, and non probiotic birds had longer villi than probiotic birds. On day 22, vaccinated birds had significantly increased chicken IgG levels compared to the control and ionophore birds, and the non probiotic birds had significantly increased IgG secretion compared to probiotic fed birds. On day 36, the ionophore birds had significantly increased levels of IgG compared to the control birds, which could also support that the ionophore delayed exposure to the parasite. These results suggest that gut morphology and humoral immunity are affected by probiotic administration, coccidiosis vaccination, ionophore application and Eimeria challenge. Both the day 43 morphology results and day 36 chicken IgG results for the ionophore treated birds demonstrates that ionophore administration delays exposure of the avian gut to invasive coccidia. More research is necessary to evaluate how probiotics influence coccidiosis vaccination and humoral immunity, so that probiotics may be used to improve the effectiveness of coccidiosis vaccination and to evaluate if probiotics aid in ameliorating the effects of an Eimeria infection.

Student Number : 9613963J - PhD thesis - School of Animal, Plant and Environmental Sciences - Faculty of Science / Animals living in cold environments show physiological, morphological and behavioural adaptations to low temperatures. The African ice rat, Otomys sloggetti robertsi, which is endemic to the southern African Drakensberg and Maluti mountains above 2000m, is an interesting exception since, unlike most alpine small mammals, it does not hibernate or display torpor and is physiologically poorly adapted to low temperatures. It is a strict herbivore, feeding on a low quality diet. Ice rats do show some morphological (e.g. short tails) and behavioural (e.g. communal huddling; constructing underground burrows) adaptations, but little else is known about their biology, particularly how they maximise energy gain to meet thermoregulatory requirements, especially during cold periods. Since feeding represents the primary method of energy gain in endotherms, I studied aspects of the foraging biology of ice rats, including gut structure, foraging patterns and habitat choice. The gut structure of O. s. robertsi is well adapted for a high fibre, herbivorous diet and shows broad similarities with those of its mesic- and arid-occurring relatives. However, O. s. robertsi showed increased dimensions of several foregut organs which may be adaptations for increased energy uptake and/or poor diet quality in alpine environments. Furthermore, females had a larger stomach as well as a longer caecum, small and large intestine in summer than in winter but the gut of males was unaffected; such sexual asymmetry may be related to increased energy requirements of females during pregnancy and lactation. Environmental influences on the aboveground behaviour of O. s. robertsi were investigated by recording the duration of behaviours as well as sequential transitions among behaviours. Ice rats spent most of their day foraging and basking, and much time was spent in their underground burrows. Seasonal comparisons revealed that ice rats spent significantly more time acquiring energy through foraging in winter, whereas they remained below ground for longer periods of time during the middle of the day in summer to escape extreme heat and solar radiation. To understand how low temperatures and predation influenced foraging patterns, the behaviour of ice rats was studied in summer and winter in a population where predators were minimal and in another population which experienced higher levels of predation. Ice rats are central place foragers that travel short distances to forage and display significant seasonal variation in their foraging patterns. In the absence of predation risk, ice rats generally returned to a central place with forage, even though returning to a burrow after foraging in winter was energetically costly. However, these costs must be weighed against the benefits of avoiding exposure to low temperatures by feeding under cover as well as the loss of collected food and possible injury associated with aggressive interactions with conspecifics. Under moderate predation pressure in both seasons, ice rats followed a central place foraging strategy to minimise predation risk, always returning to a burrow entrance with forage collected elsewhere. However, when no perceivable threat was observed, ice rats displayed ‘optimal’ foraging patterns in summer similar to those recorded in the absence of predation pressure and only returned to a burrow with forage as distance from that burrow increased, suggesting that ice rats display facultative foraging decision making in response to multiple environmental cues. The distribution of occupied ice rat burrows was correlated against several environmental factors to determine microhabitat requirements. Ice rat burrows were situated in close proximity to herbaceous and wetland plants, but away from woody vegetation, suggesting that habitat choice is related to the presence of food plants and reduction of shade, facilitating short travel distances during foraging as well as promoting basking. Despite the physiological shortcomings of ice rats, the gut structure, foraging behaviour, and habitat choice of the taxon are adapted for life in cold alpine habitats, most likely by maximising energy intake. Similarities in foraging behaviour and habitat use between O. s. robertsi with its closely-related arid-occurring relative Parotomys spp. suggest phylogenetic influences, but it is possibly more a reflection of similar phenotypic responses to the extreme habitats inhabited by these otomyines.

A series of experiments were conducted to explore factors affecting transfer of value-added ingredients from the diet to table eggs, with the goal of contributing to improvements in the enrichment process. Flaxseed-based ω-3 PUFA enrichment did not reduce lutein enrichment. The combine enrichment of lutein and ω-3 PUFA had decresed lipid oxidation potential. Also, when fed a ω-3 PUFA diet, birds scored as energetic Efficient had longer and wider villi, resulting in greater absorptive surface area/villi than Non-efficient hens. However, histomorphological differences did not affect transfer of ω-3 PUFA from diet to egg. Finally, birds fed graded levels of ω-3 PUFA to characterize change in lipid profile of egg and blood plasma in time reached a plateau in total ω-3 PUFA/egg in 5.9 to 6.6d, with High birds reaching the target of 300 mg/egg in 5d. Egg enrichment can be modulated by changes to the hen diet. / Animal Science

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Thesis (M. Sc. Agriculture (Animal Production)) -- University of Limpopo, 2021 / Two experiments were conducted to determine the effect of replacing soya bean meal with yellow mealworm larvae meal (Tenebrio molitor) in a diet on productivity, gut morphology, carcass characteristics and bone morphometrics of Ross 308 broiler chickens aged one to 42 days. In each experiment, a total of 360 Ross 308 broiler chickens were randomly assigned to the five dietary treatments, each treatment having four replications, and 18 chickens per replicate. Five diets were formulated to contain yellow mealworm replacement levels at 0, 25, 50, 75 and 100% to meet the nutrient requirements of Ross 308 broiler chickens. Data was analysed using the General Linear Model procedures of the Statistical Analysis System, Version 9.3.1 software program. Fisher’s least significant difference (LSD) test was applied for mean separation where there were significant differences (P<0.05). A quadratic regression model was used to determine the levels for optimal responses in the variables measured. The first experiment determined the effect of replacing soya bean meal with yellow mealworm larvae meal on productivity and gut morphology of unsexed Ross 308 broiler chickens aged one to 21 days. Replacement of soya bean meal with yellow mealworm meal in a diet had no effect (p > 0.05) on feed intake, growth rate, FCR, live body weight, ME intake and nitrogen retention of unsexed Ross 308 broiler chickens aged one to 21 days. Replacing soya bean meal with yellow mealworm meal in a diet did not affect (p > 0.05) caecum weight of unsexed Ross 308 broiler chickens. However, replacing soya bean meal with yellow mealworm meal in a diet increased (p < 0.05) gastro intestinal tract, crop, ileum and large intestine weights. Crop and ileum lengths of unsexed Ross 308 broiler chickens aged 21 days were not affected (p > 0.05) by replacement of soya bean meal with yellow mealworm meal in the diet. However, replacing soya bean meal with yellow mealworm meal in a diet increased (p < 0.05) gizzard, caecum and large intestine lengths of unsexed Ross 308 broiler chickens aged 21 days. Yellow mealworm meal in a diet did not affect (p > 0.05) gut organ digesta pH values of unsexed Ross 308 broiler chickens aged 21 days. The second experiment determined the effect of replacing soya bean meal with yellow mealworm meal in a diet on productivity, gut morphology, carcass characteristics and bone morphometrics of Ross 308 broiler chickens aged 22 to 42 days. Replacement of soya bean meal with yellow mealworm meal in a diet did not affect (p > 0.05) growth rate, FCR, ME intake and nitrogen retention of male Ross 308 broiler chickens aged 22 to 42 days. However, replacing soya bean meal with yellow mealworm meal in a diet affected (p < 0.05) feed intake and live body weight of male Ross 308 broiler chickens aged 22 to 42 days. Broiler chickens on diets containing 75 or 100% yellow mealworm meal had higher (p < 0.05) intakes than those on diets containing no yellow mealworm meal. Similarly, male broiler chickens on diets having 50% yellow mealworm meal had higher (p < 0.05) live body weights than those on diets containing no yellow mealworm. Quadratic equations indicated that feed intake and live body weight of male Ross 308 broiler chickens were optimized at yellow mealworm meal replacement levels of 13 and 61%, respectively. The present study showed that replacing soya bean meal with yellow mealworm meal in a diet did not affect (p > 0.05) gut organ digesta pH values, gut organ weights, gut organ lengths, meat colour, meat pH values, bone morphometric values, carcass part weights and meat sensory attributes of male Ross 308 broiler chickens aged 42 days. However, meat from chickens on diets containing yellow mealworm meal was softer (p < 0.05) than meat from chickens on diets having 100% soya bean meal. It is concluded that soya bean meal can be replaced with yellow mealworm larvae meal in a diet at 25, 50, 75 and 100% levels without having adverse effects on production and carcass characteristics of Ross 308 broiler chickens aged one to 42 days