Broiler performance under high stocking densities

Abstract

1. In two consecutive experiments a total of 4,780 broilers were reared at high stocking densities. 2. In experiment 1, the birds were housed at 10, 20, 30, 40 or 50/m2 till 6 weeks. In experiment 2 densities of 20, 40 and 50/m2 were compared; the two higher densities were reduced to 30/m2 at either 3 or 5 weeks of age. 3. In the first experiment 6-week body weight was a curvilinear function of stocking density. Average food intake over the whole experimental period declined linearly with densities above 20/m2. 4. A slight but significant improvement in the efficiency of food utilisation was recorded from birds at high densities in the first experiment only. 5. Reducing the stocking density from 40 or 50/m2 to 30/m2 at 3 weeks increased food consumption and body weight gain and led to a recovery in their body weight by 6 weeks. 6. No significant differences were observed in mortality as a result of high stocking densities in either experiment. 7. Profit margin per m2 increased almost linearly in experiment 1, by about 65 p for every bird/m2 increase in stocking density. 8. The implications for poultry welfare are briefly discussed.

Welfare of broiler chickens

“…In intensive commercial production the use of ventilation along with the adoption of curtains to increase the air speed has spread due to the beneficial effects on bird welfare in relation to the heat dissipation. The effect of stocking density on feed conversion rate is controversial since some authors found that this trait improved or worsened at high stocking densities whereas others did not observe any effect (Shanawany, 1988;Bessei, 1993;Meluzzi et al, 2008). Shanawany (1988) reported an increased mortality rate as stocking density increased.…”

“…The effect of stocking density on feed conversion rate is controversial since some authors found that this trait improved or worsened at high stocking densities whereas others did not observe any effect (Shanawany, 1988;Bessei, 1993;Meluzzi et al, 2008). Shanawany (1988) reported an increased mortality rate as stocking density increased. In a field trial carried out on 270,000 broiler chickens, Meluzzi et al (2007) did not find any relationship between mortality and stocking rate thereby confirming previous findings of Cravener et al (1992).…”

“…Several studies have been carried out on broiler stocking density ranging from 10 to 50 kg/m 2 floor space (Shanawany, 1988;Grashorn and Kutritz, 1991;Meluzzi et al, 2003Meluzzi et al, , 2004. It is well documented that with stocking density over 30 kg/m 2 floor space growth rate is reduced as a result of the heat stress (McLean et al, 2001).…”

Effect of density and flock size on growth performance of native chicken

“…Feed intake, ambient temperature, relative humidity, density and flock size are the major environmental variables influencing growth of native chicken. Density has an important and marked effect on growth of chicken (Shanawany, 1988). It affects feed intake, feed efficiency, livability (Cocnen et al, 1996) that as a whole influence the growth of chicken.…”

Comparison of Stress Response between Korean Native Chickens and Single Comb White Leghorns subjected to a High Stocking Density

“…이와 더 불어 최근 개체의 스트레스 반응 정도를 직접적으로 나타낼 수 있는 유전자 표지로서 heat shock protein(HSP) 계열의 유 전자 및 hydroxyl-3-methyl-glutaryl coenzyme A reductase (HMGCR) 유전자의 발현율이 소개되고 있는데, 닭에 있어 서도 열 스트레스 반응과 관련하여 이들 표지들이 널리 이 용되고 있다 (Kregel, 2002;Gornati et al, 2004;Beloor et al, 2010;Soleimani et al, 2011;Sohn et al, 2012 (Thaxton et al, 2006;Zimmerman et al, 2006;Delezie et al, 2007;Keles et al, 2010). 특히 고밀도 사육의 경우, 브로일러에서 체중 및 사 료 섭취량의 감소뿐만 아니라, 다리 이상 개체 발생 빈도의 증가 등 생산 능력의 저하를 초래한다고 하였다 (Shanawany, 1988;Beloor et al, 2010). 또한 고온 스트레스 환경에 노출 된 산란계의 경우, 사료 섭취량, 증체량, 산란율, 난중 및 난 (Schlesinger, 1986;Zulkifli et al, 2002), hydroxyl-3-methyl-glutaryl coenzyme A reductase(HMGCR)는 cortisol 의 생합성을 조절하는 인자이다 (Gornati et al, 2004).…”