A total of 280 weaned pigs (Landrace x Yorkshire x Duroc) were used in a 28-d growth study to investigate the effect of feeding different levels of potato proteins on growth performance, nutrient digestibility, immune response, small intestinal morphology, and bacterial populations in feces and large intestine. Pigs (initially 6.42 +/- 0.74 kg of BW and 23 +/- 3 d of age) were randomly allotted to 5 treatments on the basis of BW, each treatment composed of 4 pens, each pen having 14 pigs. Dietary treatments included positive control (PC; basal diet + 150 mg/kg apramycin and 10 mg/ kg colistin sulfate); and potato protein (PP), consisting of the basal diet with 0, 0.25, 0.50, or 0.75% of potato protein. Diets were fed in 2 phases: phase I (d 0 to 14 postweaning) and phase 2 (d 14 to 28 postweaning). Potato protein was extracted from a value-added type of the new potato variety, Solanum tuberosum L. cv. Gogu valley, and was shown to have a minimum inhibitory concentration of 300 to 500 mug/mL. Performance of PC was compared with 0.25 to 0.75% PP, whereas linear and quadratic trends of increasing PP (0 to 0.75% PP) were tested. Over the 28-d trial, pigs fed the PC diets showed improved overall ADG (P < 0.05) and G:F (P = 0.090) compared with pigs fed PP, whereas increasing levels of PP linearly improved ADG (P < 0.05), ADFI (P = 0.052), and G:F (P = 0.098). The digestibility of DM and CP in both the phases was greater in PC than PP, and feeding of PP linearly improved the DM digestibility (P < 0.05) in phase II. The bacterial populations in the feces of pigs fed PC and PP were comparable, except for total bacteria and coliform bacteria in the feces at d 14 and 28, which were decreased in PC; and feeding of PP was effective in linearly reducing the populations of microbes in feces and contents of cecum, colon, and rectum. There was linear increase (P < 0.10) in skin-fold thickness in response to phytohemagglutinin with an increase in PP levels. Haemagglutinin titers on d 21 were greater (P = 0.054) in PC, and at d 28 the haemagglutinin titers were quadratically affected in pigs fed PP (P = 0.070). There was a trend toward a decrease in crypt depth (P = 0.068) and a greater villus height:crypt depth ratio (P = 0.082) of ileum in PC compared with PP. These results suggest that PP may be an alternative to medicated feed with antibiotics because it showed antimicrobial activity by effectively reducing the population of coliform bacteria and also improved the performance of weanling pigs.

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요 약본 연구는 다양한 유기산제들의 급여가 이유자돈의 성장과 영양소 소화율에 미치는 영향을 비교하기 위하여 2번 의 사양실험을 수행하였다. 실험 1과 실험 2에서는 각각 이유자돈 180두 (4처리, 3반복, 15두/반복)를 공시하였다. 실 험 1은 기초사료에 formic acid, ammonium-formate, lactic acid 그리고 acid mixture를 각각 0.5%씩 첨가하여 총 5주간 사양실험을 실시하였으며, 실험 2는 formic acid, ammonium-formate, lactic acid 그리고 acid mixture를 각각 0.3%씩 첨 가하여 총 6주간 사양실험을 실시하였다. Acid mixture는 formic acid와 lactic acid가 50:50의 비율로 혼합된 제제를 사용하였다. 외관상 회장아미노산 소화율을 측정하기 위하여 각 처리별 3두, 총 12두를 공시하여 T-cannula를 회장 말단부에 부착시킨 후 적응기간을 거쳐 회장내용물을 채취하였다. 사양성적은 유기산 종류에 따른 개선 효과는 없 는 것으로 나타났으나 (실험 1), acid mixture 급여구에서 증체량이 lactic acid 급여구보다 높은 것으로 나타났다 (실험 2). 외관상 회장 아미노산 소화율은 lactic acid 급여구보다 acid mixture 급여구에서 개선되는 것으로 나타났다 (실험 1과 2). 실험 1과 2의 결과를 종합하였을 때 acid mixture (formic acid + lactic acid) 급여는 이유자돈의 사양성적과 외관상 회장 아미노산 소화율을 개선시키는 것으로 판단된다.