To be economically profitable, the poultry industry demands an increase in stocking density, which could adversely affect chicken welfare. The current study was performed to investigate the effect of stocking density on stress-related, heat shock protein genes (HSP70 and HSP90), 3-hydroxyl-3-methyl-glutaryl coenzyme A reductase (HMGCR) gene and telomere length in broiler chickens. Seven-day-old broiler chickens were housed at High (0.0578 m 2 /bird), Standard (0.077 m 2 /bird) and Low (0.116 m 2 /bird) stocking densities with 8 replicates each until 35 d of age. The growth performance, such as body weight gain and average daily feed intake, was found to be significantly (p<0.05) higher in the Low density group, but these parameters did not show any difference between the High and Standard groups. Other growth performance, such as feed conversion ratio and final feed intake, showed no difference among the treated groups. The expression levels of HSP70 and HMGCR were found to be elevated with the increase of stocking density. The expression level of these genes was significantly (p<0.05) higher in the High density stocked group compared with the other groups, whereas the expression levels were not significantly different between the Low and Standard groups. The expression levels of HSP90 did not show any significant changes among the treated groups. The telomeric length of the birds housed in High density was reduced significantly (p<0.05) when compared to that of the birds in Low density. These results clearly indicate that birds stocked at high density show physiological adaptive changes indicative of stress at gene transcriptional and telomere levels.

This work was carried out to investigate performance and carcass yield of large-type broiler females at different stocking densities. Chicks (n = 492; 1-day-old; female; Arbor Acre broiler) were reared for six weeks (starter, 0～1 wk; earlier, 1～3 wk; finisher, 3～6 wk) and randomly divided into 3 treatments (4 replications/treatment, 36, 41 or 46 birds/replication). Treatments were T1 (10.9 birds/m 2 ), T2 (12.4 birds/m 2 ) and T3 (13.9 birds/m 2 ) by the stocking densities. Research indexes were livability, body weight, body weight gain, feed intake, feed conversion ratio, production efficiency factor, carcass yield and primal cuts ratio (wing, leg, back, breast and neck). Livability (%) was 90% or more for all treatments, but there was no significant difference on weekly livability (%). Body weight of T3 treatment were the lowest at 3 wk and body weight gain, feed intake, and feed conversion ratio were the lowest at 2～3 wk (P<0.05). Production efficiency factors of T1, T2 and T3 were 331.0, 340.8 and 336.0, respectively, and there was no significant difference among treatments. Leg meat ratio of T2 treatment was higher compared to other treatments at the age of 4 wk (P<0.05). Carcass yield of T1 treatment was the highest as 76.2% at the age of 5 wk (P<0.05). However, there was no significant difference on carcass ratio and partial meat ratio among treatments at the age of 6 wk. This result may provide the standard data of different stocking densities for heavy female broilers.(Key words : large-type broiler, female, performance, carcass ratio, partial meat ratio) a First two authors equally contributed to this work. † To whom correspondence should be addressed : drhong@rda.go.kr

To investigate the effects of dietary substituent of corn distiller's dries grains with solubles (CDDGS) on the amino acid digestibility of broiler diet, twenty four Ross broilers (6-wk-old) were used in this study. Basal diet (CP 19%, ME 3,150 kcal/kg) was formulated on corn-soybean meal and two levels of CDDGS (6 and 12%) were supplemented to basal diet. CDDDS levels (0, 6 and 12%) and 4 different sites of chicken intestines (distal end of jejunum, the middle part of the ileum, the distal end of ileum and the distal end of the rectum) were evaluated factorial as 3×4 three arrangement. Statistical analysis did not show any significant interaction between dietary treatments and the sites of the intestines in amino acid digestibility (P>0.05). There was no significant difference among the sites of chicken intestines in the digestibility (P<0.05). The digestibility of lysine (essential amino acid) and glycine (non-essential amino acid) decreased at increasing supplementation of CDDGS (P<0.05). There was no significant difference on the digestibility of other amino acids studied. In conclusion, the result of this work showed that CDDGS can use as alternative resources in broiler diets.(Key words : CDDGS, amino acid, digestibility, ileum, broiler) a First two authors equally contributed to this work. † To whom correspondence should be addressed : kohb@rda.go.kr 따라서 최근의 연구들은 다양한 축종에 대하여 사료용 옥수 수를 대체하기 위한 연구 (Mateoes et al., 2006(Mateoes et al., , 2007 Nyannor et al., 2007; Donkin et al., 2009; Archimede et al., 2010)

This work was carried out to investigate performance and carcass yield of large-type broilers at different stocking densities. Treatments were T1 (9.1 birds/m 2 ), T2 (10.3 birds/m 2 ) and T3 (11.5 birds/m 2 ) by the stocking density. Four hundred eight 1-day-old Arbor Acre broiler chicks were used for six weeks (starter, 0～1 wks; earlier, 1～3 wks; finisher, 3～6 wks) and divided into 3 treatments (4 replications/treatment, 30, 34 or 38 birds/replication). Research indexes were rearing viability ratio, body weight, body weight gain, feed intake, feed conversion ratio, production efficiency factor and carcass ratio. Rearing viability ratio (%) was 89% or more for all treatments and there was no significant difference on weekly rearing viability ratio (%). Body weight of T2 was the greatest and that of T3 was the lowest at 1 weeks old (P<0.05). Body weight gain of T2 was the greatest and that of T3 was the lowest at 0～1 weeks old (P<0.05). However, body weight gain of T3 was the greatest and that of T1 was the lowest at 1～2 weeks old (P<0.05). Body weight gain of T2 was the greatest as 3,031 g among treatments at 0～6 weeks old (P<0.05). Feed intakes of T1, T2 and T3 were 1,417 g, 1,265 g and 1,355 g, respectively, and that of T1 was the greatest among treatments (P<0.05). There was no significant difference on body weight, body weight gain and feed intake. Feed conversion ratio of T1 was the greatest among treatments at 1～2 wks, 3～4 wks and 0～6 wks old (P<0.05). Production efficiency factors of T1, T2 and T3 were 363.5, 388.3 and 358.3, respectively, and there was no significant difference among treatments. Wing meat ratio of T1 was the higher compared to other treatments at the age of 4 wk (P<0.05). There was no significant difference on carcass ratio and partial meat ratio among treatments. Neck meat ratio of T2 was the lowest among treatments (P<0.05). This result may provide the standard data of different stocking densities for large-type broiler and the further research is needed.(Key words : large-type broiler, performance, carcass ratio) † To whom correspondence should be addressed : drhong@rda.go.kr 서 론 육계 산업에서 사육 밀도의 증가는 노동력, 계사 및 설비와 관련된 비용을 절감시키는데 사용되는 경영 방식이다. 그러 나 사육밀도가 높아지면 결과적으로 증체량, 사료 섭취량 및 사료 요구율과 같은 성장 생산성이 감소된다 (Puron et al., 1995;Feddes et al., 2002;Dozier et al., 2005Dozier et al., , 2006Estevez, 2007). 게다가, 가슴육과 같은 부분육 생산은 높은 사육밀도 에 의해 감소된다 (Dozier et al., 2006).사육밀도가 높아지면 육계의 복지 상태에 악영향을 미친 다. 육계의 성장과 건강은 사육밀도에 영향을 받기 때문에 (Webster, 1990)

This work was carried out to evaluate the feces and ileal digestibility of canola meal and wheat bran in ducks. Ninety Pekin ducks (6-week-old, average 3.4 kg) were divided into three treatments (6 replications/treatment, 5 birds/replication) by feedstuffs (basal diet, canola meal, and wheat bran) and were fed on these diets in individual metabolic cages for one week. After one week, the samples for analysis were collected from feces and ileum. On comparison of treatments and collected sites, the feces digestibility of basal diet was the highest among treatments on chemical compositions except crude protein and crude fat and ileal digestibility of canola meal was the lowest (P<0.01). On comparison of treatments, the digestibility of basal diet was higher and that of wheat bran was lower when compared to other treatments (P<0.05). The feces digestibility was lower than the ileal digestibility in crude protein (P<0.05) and crude fat (P<0.01). The digestibility of amino acid was the highest at feces of control group among treatments (P<0.01). No significant difference was detected in terms of digestibility of isoleucine, leucine and phenylalanine among essential amino acids, and alanine, glycine and tyrosine among non-essential amino acids between control and wheat bran, and wheat bran and canola meal. However amino acid digestibility was higher in control group when compared to canola meal group (P<0.05). Other amino acid digestibilities were not significantly differ by treatments. These results may provide the basic data on amino acid digestibility of ducks to evaluate feedstuffs and to formulate optimum diet for commercial Pekin duck.(Key words : duck, digestibility, amino acid, canola meal, wheat bran) † To whom correspondence should be addressed : drhong@korea.kr Huang et al., 2005;Ravindran et al., 2005). 그러 나 맹장에 존재하는 미생물에 의하여 아미노산 성분이 변화 되기 때문에, 가금류에서는 회장 소화율이 분 소화율에 비 해 실질적이고 정확한 방법으로 인식되고 있다 (Ravindran et al., 1999). 따라서 몇몇 연구들은 다양한 사료 원료, 품종 및 닭의 주령에 대한 회장 아미노산 소화율에 대한 자료를 제