This study investigated the effect of adding poultry litter additive containing probiotics and amino acids to the litter on weight gain in ducks and ammonia content in poultry litter. Nine hundred 1-day-old ducks (Pekin) were randomly distributed into three groups (300 birds per treatment divided into three replicates) using a randomized block design. Treatments were top-dressed on the litter surface at rates of 2 kg poultry litter additives (T1) and 2 kg macsumsuk (T2) per m2, and untreated poultry litter was used as the control. Overall, a significant difference (p<0.05) in weight gains was observed at 3 and 4 weeks, but not at 5 and 6 weeks. After 4 weeks, when compared to other treatments, the addition of poultry litter additive tended to increase the average body weight gain (90-130 g). The ammonia content was affected by all treatments (p<0.05) over time except at 3 weeks, however, compared to other treatments, the poultry litter additive decreased the ammonia content. In particular, the rate of ammonia reduction by the poultry litter additives over time was approximately 20.2%-49.2%. Regarding temperature, a significant difference was observed in all treatment groups (p<0.05), except at 3 weeks. In conclusion, considering poultry litter additives and temperature, the increase in duck weight gain was associated with a decrease in ammonia content in the poultry litter.

Abstract
1. 서 론
2. 재료 및 방법
3. 결과 및 고찰
4. 결 론
REFERENCES

• 장우환(경북대학교 농경제학과) | Woo-Whan (Department of Agricultural Economics, Kyungpook National University, Daegu 41566, Korea)
• 김창만(영남대학교 물리학과) | Chang-Man, Kim (Department of Physics, Yeungnam University, Gyeongsan 38541, Korea)
• 최인학(중부대학교 애완동물자원학전공) | In-Hag, Choi (Department of Companion Animal & Animal Resources Science, Joongbu University, Geumsan 32713, Korea) Corresponding author