The first study was conducted to evaluate the dietary inclusion of effective microorganisms (EM) on body weight (BW), feed intake, feed conversion ratio (FCR) and mortality of broilers, which had been either challenged or non-challenged with Clostridium perfringens (1mL of 1 x 108 CFU/mL orally). Six hundred and forty day-old Ross 788 broiler chicks were randomly allocated to thirty-two pens in groups of twenty birds per pen, giving a stocking density of ±18 birds per square meter from zero to forty days of age. The facility consisted of two rooms with sixteen pens per room. All the chicks were fed on a commercial maize-soya type diet, including a mash starter and a mash grower/finisher feed. At two weeks of age 320 chicks were inoculated with Clostridium perfringens type A through oral administration. The study had a randomised block design with four replicates and four treatments as: 1) Control-unmedicated; 2) antibiotic growth promoters (AGP) added to feed at 33g/kg; 3) EM added to feed and water at 50g/kg and 50mL/L respectively; and 4) AGP in feed at 33g/kg and EM (50g/kg) in feed and water (50mL/L). The inclusion of EM negatively affected water palatability that resulted in reduced water intake and increased FCR for the non-challenged broilers at 21 days of age. However, because feed intake was not affected, it was suggested that EM should rather be supplemented through the feed rather than through the water. The use of AGP alone or in combination with EM proved (P<0.05) broiler production performance. The cumulative feed intake, BW, FCR, average daily gain (ADG), cumulative water intake and production efficiency factor (PEF) of challenged broilers were not different (P>0.05) at 40 days of age. In this study the incidence of mortality was low (2.2%) and examination of livers and intestines showed only mild necrotic enteritis lesions. In conclusion, the findings of this study showed that EM under the current dosage failed to improve broiler production performance. A second experiment was conducted as a follow-up study to evaluate the effect of EM on broiler performance when supplemented through the feed only. Cloacal swabs were taken from all day-old chicks and a day after inoculation with Clostridium perfringens for laboratory analysis of the microorganisms in the gut. All the chicks were fed on a commercial two-phase maize-soya type diet consisting of a mash starter and a mash grower/finisher feed with additional fishmeal. The chicks from one room were inoculated orally with Clostridium perfringens, while the chicks from the other room remained unchallenged. The challenged group was inoculated orally with 1 mL (1 x 108 CFU/mL) of Clostridium perfringens as a single dose on day 14. The EM was supplemented to the broilers from day one through the feed. The supplementation of EM through the feed showed a poor performance for non-challenged whilst for the challenged showed an improved performance at 3 weeks. Both non-challenged and challenged broilers given EM had a poor performance at 6 weeks of age, and this showed inconsistent results throughout the experiment. However, it was found that the combination of both AGP and EM had a better performance than EM alone. It is noted when the results of broilers nonchallenged versus challenged control groups were compared, the challenged ones showed a better performance. The broilers showed a low mortality of 1.3% and the causes were not related to the incidence of necrotic enteritis. The gross examination of the broilers inoculated orally with Clostridium perfringens showed mild intestinal lesions. Copyright
Dissertation (MSc(Agric))--University of Pretoria, 2010.