Two feeding trials were conducted with pigs to determine the effects of blueberry supplementation on plasma lipid levels and other indices of cardiovascular benefit. In the first trial, where basal diets contained a high level of plant-based components (70 % soya, oats and barley), supplementation with 1, 2 and 4 % blueberries resulted in a decrease in total, LDL-and HDL-cholesterol. The greatest reduction was observed in the 2 % blueberry-fed pigs, where total, LDL-and HDL-cholesterol were reduced 11·7, 15·1 and 8·3 %, respectively. In the second trial where basal diets contained only 20 % (w/w) of soya, oats and barley, the lipid-modulating effect of blueberries was attenuated, so that supplementation with 1·5 % blueberries reduced total cholesterol by 8 %, which occurred only in pigs whose diets had been supplemented with cholesterol (0·08 %), NaCl (0·11 %) and fructose (9 %). In the first feeding trial, blueberry supplementation had no effect on blood platelet activity. Blueberry supplementation also had no effect on the susceptibility of leucocyte DNA to oxidation in the first trial and no effect on the susceptibility of LDL to oxidation in the second trial. Results of these two feeding trials are discussed in relation to the effects of basal diet composition on lipid-modulating effects of blueberries.

An experiment was conducted to examine the effects of dietary lysine/digestible energy (DE) ratio (g/MJ) on growth performance and body composition of boars, gilts and castrated males from 25 to 90 kg live weight. Twelve pigs (four of each sex) were assigned to each dietary treatment consisting of lysine/DE ratios from 0·4 to 1·4, in 0·2 g/MJ increments. Food was provided at proportionately 0·90 ad libitum and at 90 kg all pigs were slaughtered and the body composition of two pigs per sex per treatment was determined. Responses to lysine/DE ratios were similar for all sexes up to the optimum level after which daily live-weight gain (DLWG) and nitrogen deposition rate (NDR) deteriorated in gilts and castrated males. This deterioration may have been due to energy used for deamination of excess protein not being availablefor growth processes. Lipid deposition rate (LDR) remained constant from the 0·4 to 0·8 g/MJ lysine/DE ratios and then decreased sharply to a lower plateau from the 1·0 to 1·4 g/MJ lysine/DE ratios suggesting that DE levels were adequate to meet NDR requirements up to the 1·0 g/MJ lysine/DE ratio when it became limiting. The optimum lysine/DE ratio for the genotype tested from 25 to 90 kg live weight was of the order of 0·95 to 1·0 g/MJ. The maximum NDR of the genotype tested appears to be of the order of 28 to 30 g/day (175 to 187 g/day protein deposition rate).

The purpose of this review is to discuss the issue of subtherapeutic use of antibiotics in pork production and possible alternatives. Specifically, the review describes the potential problem of antibiotic resistance and reviews disease prevention and immune potentiation strategies as alternatives to subtherapeutic antibiotics. In recent years, the use of in-feed subtherapeutic antibiotics by the pork industry for growth promotion and disease prophylaxis has come under increased scrutiny. The potential risk of bacteria acquiring resistance to specific antibiotics and the detrimental effects that this may have on human health has resulted in the banning of certain antibiotics in some European countries. Despite the current interest in the reduction or elimination of subtherapeutic antibiotic use in livestock production, there may be a risk that such a reduction or elimination would have negative effects on animal welfare, nutrient utilization, manure production and economic sustainability. A number of alternatives to subtherapeutic antibiotics appear promising; however, more research is required before they can be considered viable commercial products. Consequently, a systems approach involving nutrition, bacteriology, immunology, pathology and herd management is needed to find a cost-effective and practical way to maximize the efficient production of high-quality pork without the use of subtherapeutic antibiotics. Key words: Pig, pork production, subtherapeutic antibiotics, alternatives

An experiment was conducted to examine the effects of dietary lysine/digestible energy (DE) ratio (g/MJ) and dietary energy concentration on growth performance and body composition of young hybrid gilts from 9-1 to 25-4 kg live weight. Seven pigs were assigned to each of 10 dietary treatments consisting oflysine/DE ratios from 0-6 to 1-4 in 0-2 g/M] increments and two ). Food was provided ad libitum and at 25-4 kg all pigs were slaughtered and body composition was determined. Responses to lysine/DE ratios were different for each DE concentration. The pigs given the 16-40 MJ/kg DE diets had a higher daily liveweight gain (DLWG) and nitrogen deposition rate (NDR) than those given the 14-25 MJ/kg diets up to the 1-2 gl MJ lysine/DE ratio. Beyond this point no DE effects were evident. Lipid deposition rate (LDR) was higher for all 16-40 MJ/kg diets as compared with the 14-25 MJ/kg diets and decreased with increasing lysine/DE ratio. The 14-25 MJ/kg diets resulted in increasing efficiency of nitrogen and gross energy utilization with increasing lysinel DE ratio up to the 1-0 g/MJ ratio after which it declined. Efficiency of lipid utilization decreased with increasing lysine/DE ratio for all 14-25 MJ/kg diets. The 16-40 MJ/kg diets resulted in a decrease in nitrogen and gross energyutilization efficiency with increasing lysine/DE ratio while lipid efficiency decreased up to the 1 -0 g/MJ lysine/DE ratio after which it increased. Young hybrid pigs given high energy diets appear to be less sensitive to dietary lysine/DE ratio than those given lower energy diets. The optimum lysine/DE ratio for the genotype tested from 9 to 25 kg live weight was of the order of 1-2 g/MJ for both DE concentrations. The maximum DLWG and NDR of the genotype tested over the live-weight range of 9 to 25 kg appears to be of the order of 620 and 17 g/day (106 g/day protein deposition rate) respectively.

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