Effects of lighting, stocking density and perch using on leg health, fear and stress parameters as welfare criteria on broiler chickens

This study was conducted to investigate the effects of lighting programme, stocking density, and perch usage on leg health and fearfulness and stress parameters of which is well-known animal welfare criteria. During the 42 days study, a total of 360 commercial broilers (180 male and 180 female; Ross 308) were used as an animal material. Factors consisted of lighting programme, stocking density and perch application were designed as two different levels so as to fit 2x2x2 factorial design. Tibial dyschondroplasia, valgus-varus deformity, foot pad dermatitis, hock burn, tibial cortical index, robusticity index, bone weight-length index, fluctuating asymmetriy and relative fluctuating asymmetriy of tibia width and length, tibia crude ash, tibia calcium and phosphorus levels, blood calcium and phosphorus levels, were investigated as leg health parameters. Tonic immobility test was performed for fearfulness while blood heterophil to lymphocyte ratio, glucose, total protein, cholesterol and triglyceride levels were measured for stress reactions. Tibial dyschondroplasia incidence was detected as 26,4% and 11,2% in animals in continuous and restricted lighting groups, respectively. The effect of lighting programme on tibial dyschondroplasia incidence was found as statistically significance (P<0,05) while there was no same effect arising from stocking density and perch usage. The effect of lighting programme and stocking density on the degree of foot pad dermatitis was found insignificant while the presence of perch has significant (P<0,01) effect on this dermatitis. The effect of lighting on the level of hock burn lesions was determined as insignificant while stocking density and perch usage have statistically significant effects. The presence of perches in the pen has significant (P<0,001) effects on the formation of hock burn lesions and hock burn incidence and intensities were also recorded lower in these animals. It was determined that lighting programme has significant effect on serum phosphorus level while perch usage and gender have same effects on serum calcium level (P<0,05). Lighting program has statistically significant (P<0,01) effect on 42nd day cortical index. And cortical index was calculated as 38,81 and 36,28 in restricted and continuous lighting programme groups, respectively. It was determined that lighting programme, stocking density, perch usage have no significant effects on 21st and 42nd days robusticity index and weight-length index. It was determined that lighting programme, stocking density, perch usage and gender have no significant effects on fluctuating asymmetriy of tibia width and relative fluctuating asymmetriy of tibia width. Average fluctuating asymmetriy of tibia length was found as 0,92 and the effect of lighting programme on this index found as statistically significant (P<0,05). It was determined that lighting programme, stocking density, perch usage and gender have no significant effects on heterophil to lymphocyte ratio and tonic immobility duration. Results show that serum glucose level was not affected by lighting programme and stocking density while perch usage and gender have significant effects on this parameter (P<0,05). However, lighting programme and stocking density have statistically significant (P<0,001 and P<0,01, respectively) effects on serum total protein level while perch usage and gender have no similar effects. It was determined that stocking density and perch usage have significant effects on serum cholesterol level (P<0,05 and P<0,01 respectively) while serum cholesterol level had not been affected by lighting programme and gender. It was determined that lighting programme has statistically significant (P<0,001) effects on average live weight gain in the first three weeks period and average live weights of broilers in this period in continuous lighting group were measured higher than restricted lighting group counterparts. The effect of stocking density on average live weight was found as statistically significant (P<0,05) only for 4th, 5th, and 6th weeks. In this period, average live weights were higher in 12 bird/m2 group than 18 bird/m2 group.