No description available.

The aim of this research was, first to test the suitability of different seaweeds and formulated feeds as food for post-weaning juvenile South African abalone and secondly, to test the effects of basket design on the growth of grow-out juvenile abalone in both flow-through and re-circulation systems.

No description available.

No description available.

The objectives of this study in the Nakuru District of the Kenyan Highlands, the major milk sources for the Nairobi milk market, were to evaluate current dairy cattle rearing and feeding practices, and suggest efficient feeding management strategies on large and small-scale commercial dairy farms. 139 small-scale farms with 738 dairy cows were surveyed and 6 large-scale dairy farms with 4379 dairy cattle. On the small farms, high mortality rates, cost of AI, and disease were the major causes of poor reproduction leading to a lack of replacement stock. Feeding systems used were: 24% free grazing system, 33% semi-zero grazing, 40% zero grazing, and 3% rotational grazing, but limited feeds were available – crops and feed crop residues, cut grass on the roadside, neighbouring farms with some purchased hay and straws in the dry season. After weaning, feed supplements were rarely given to calves, priority being given to milking cows, explaining the few replacement stock kept and their high mortality. The six large scale farms were from 200 to 3500 acres with milk production, cereal crops, fodder crops, the scale of replacement dairy stock and hay to other dairy farms the main activities with land allocated 65% to livestock, 20% to cash crops (Barley and Wheat), 10% to fodder crops and 5% to other land-uses. Replacement heifers for sale were insufficient to meet demands from small-scale farms. Grazing systems were mainly extensive with supplements fed at milking.  All the farms depended on planted forage grasses, mainly: Rhodes grass, Star grass, Sudan grass and Kikuyu grass. Calf mortality rate (10-18 %) was high caused mostly by respiratory diseases and East Coast Fever. Extended age at first calving (>31.8 ± 4.5 months), long calving intervals (> 406 days) and low average milk yields (6.81/day ± 3.9) for all breeds, occurred. Production and reproductive performances needs to be addressed by proper nutrition. Suitable pasture grasses, legumes and fodder crops not currently being used have been identified as potential options to complement the existing pasture. Among these are: Guinea grass (panicum maximum), Cynodon dactylon, Buffel grass (Cenchrus ciliaris), Naivasha star grass (Cynodon plectostachyus) and Rhodesian star grass (Setaria sphacelata). Other studies examining supplementation of animals on low quality pastures with the above feeds resulted in increased body weights and milk yields. The greatest potential seems to be supplementing with home-grown proteinaceous feedstuffs such as Leucaena leucocephala, Calliandra, Sesbania or food crop residues like groundnut, cassava, sweet potato vines or pigeon-pea leaves and stems. Farmers could increase their pasture land productivity by establishing fodder grass, fodder shrubs and food crops as intercropping, hedgerows and along contour bands.

The aim of this study was to evaluate the growth supporting value of DE derived from gut fermentation in growing pigs. Unmolassed sugar beet pulp (SBP) was selected as a model material for fermentation. For a reference material which would be digested in the small intestine by the endogenous enzymes, maize starch (MS) was selected. A cereal-based control diet was formulated to fulfil the needs of pigs for all essential nutrients apart from energy. To this control diet, either SBP (150 & 300 g/kg) or MS (100 & 200 g/kg) were added. The study consisted of two phases. The first phase (digestion trial and growth trial) was devoted to studying the digestion of these diets and to comparing the effects on growth of pigs of the two DE sources (SBP and MS). The second phase was to determine the production of VFA resulting from the fermentation of SBP. Methods used included stoichiometric calculations based on measurements of the molar proportions of VFA combined with CH4 production, and a direct assessment of the true fermented materials using antibiotics to suppress fermentation. The results of the first phase showed that the energy in SBP and MS had an apparent digestibility of 0.74 and 0.98. The DE from SBP was used for supporting carcass gain with an efficiency of 0.57 of the DE from MS. The results of the second phase indicated that measurements of methane production alone or even with inclusion of free hydrogen could underestimate the extent of fermentation in the gut of pigs. The results also suggest that with the cereal-based control diet, fermentation could supply up to 13.6% of the dietary DE in the form of VFA or 18.0% in the form of fermented energy. For this control diet incorporating 30% SBP, the respective values were 25.4% and 33.4%. The absorbed VFA resulting from the fermentation of SBP had a growth supporting value of 0.763 of that of absorbed glucose from MS.

The ecological success of social insects is frequently ascribed to improvements in task performance due to division of labour amongst workers. While much research has focused on improvements associated with lifetime task specialization, members of colonies can specialize on a given task over shorter time periods. Eusocial bees in particular must collect pollen and nectar rewards to survive, but most workers appear to mix collection of both rewards over their lifetimes. We asked whether bumblebees specialize over timescales shorter than their lifetime. We also explored factors that govern such patterns, and asked whether reward specialists made more foraging bouts than generalists. In particular, we described antennal morphology and size of all foragers in a single colony and related these factors to each forager's complete foraging history, obtained using radio frequency identification (RFID). Only a small proportion of foragers were lifetime specialists; nevertheless, >50% of foragers specialized daily on a given reward. Contrary to expectations, daily and lifetime reward specialists were not better foragers (being neither larger nor making more bouts); larger bees with more antennal olfactory sensilla made more bouts, but were not more specialized. We discuss causes and functions of short and long-term patterns of specialization for bumblebee colonies.

The feeding ecologies of leaf pack-associated systellognathan stoneflies were examined from 6 June 1980 21 May 1981. Species composition, seasonal abundance, nymphal growth, feeding habits and mouthpart morphology were determined for the eight dominant stonefly species. Prey preferences and predator-prey size relationships were also examined for omnivorous and carnivorous species. Foregut analysis from 2860 individuals indicated opportunistic feeding on the most abundant prey insects, usually in proportion to prey frequency. Feeding preference studies generally indicated random feeding on major prey groups. Prey and predator sizes were usually highly correlated (p<0.01), with predators expanding their prey size thresholds with growth. The potential for competition between sympatric stoneflies for prey is discussed.

No description available.

Call number: LD2668 .T4 1952 B7 / Master of Science