Studies on comparative evaluation of layer housing systems and appropriate feeding regimen in welfare aviary

Ahammed, Musabbir Kangwon National Univ. 2013 국내박사

Studies on comparative evaluation of layer housing systems and appropriate feeding regimen in welfare aviary

Musabbir Ahammed 강원대학교 대학원 2013 국내박사

Egg production in welfare bestowing aviary housing system was evaluated in views of three different perspectives. The first study intended to compare aviary, barn and conventional cage raisings in view of laying performance and egg quality. The second study was executed to find the appropriate ME levels for hen in aviary system. The third study was executed to find the alternative method to replace forced molting practice to aged layers in aviary system. Study 1. Comparison of aviary, barn and conventional cage raisings of chicken on laying performance and egg quality This study intended to compare the productive performance of three different layer raising systems; conventional cage (CC), barn (BR) and aviary (AV). AV is welfare bestowed housing that allows free locomotion for bird within barn. BR allows bird’s free locomotion inside barn but no multilevel structures. Both pullet and cockerel were housed together in both AV and BR, but no cockerel, only pullet were housed in CC. Seventeen weeks old Lohmann Brown Lite (n = 800) pullets were housed to AV in this study. The same age layer pullets were simultaneously assigned to either at CC (n = 600) or BR (n = 200) to compare egg production performance with AV. The duration of experiment was 40 weeks (from 21st to 60th week). There were no remarkable differences in egg production (HDEP) and average egg weight among three rearing systems. First 20 weeks (phase-1) average HDEP (%) of AV, CC and BR were 85.9, 88.8, 87.1 and average egg weights (g) were 57.5, 59.9 and 56.9 respectively. Those of rest 20 weeks (phase-2) were 87.1, 87.9, 85.5 and 64.2, 63.0 62.1, respectively. Daily feed intakes (122g, 110g 125g); feed conversion ratio (2.4, 2.1, 2.5) and daily egg mass (53.9g, 54.4g 52.8g) data from AV, CC and BR were not influenced significantly by the respective raising systems. Salmonella spp. was not detected both on the surface of egg or in the litter of AV. Daily feed intake of layer in both AV (124g) and BR (127g) were tended to be higher than that in CC (113g) during phase-2. Overall, exterior egg quality (dirty and cracked eggs) in both phases was superior in BR compared with AV and CC, whereas CC generated intermediate results. But breaking strength (avg. 3.68 kg/cm2) and shell thickness (avg. 0.41mm) were better in AV and poor in CC (avg. 3.68 kg/cm2 and avg .0.37mm). Internal quality of egg, especially Haugh Unit and albumen height were always higher in CC compared to others. This study indicated that the HDEP per se in AV and BR were not significantly different from that in CC. The study implied that the facility depreciation cost for AV and cost for increased feed intake in AV compared to CC are believed to be critical to evaluate the cost effectiveness of egg production in AV. Study 2. Effects of different dietary ME levels on welfare aviary chicken at the late stage of production The experiment was performed to evaluate the effects of different dietary ME levels on aviary chicken performance. Sixty weeks old Lohmann Brown Lite layer chicken (n = 720) were randomly divided into 4 dietary treatments. Diets with four levels of metabolizable energy (ME) (2700, 2800, 2900, and 3000 kcal/kg) were supplied to welfare aviary layer chicken for 7 weeks. During the experimental period, egg production (HDEP), egg weight, body weight and feed intake were recorded. At the end of experiment, 4 birds from each treatment were assigned to measure abdominal fat and serum cholesterol level. Four birds from each treatment were also shifted to metabolic cages for digestibility trial immediately after 7 weeks feeding trial. Twenty eggs from each treatment were randomly collected to analyze different egg quality parameters and yolk cholesterol content. Dietary ME of 2800 kcal/kg significantly increased HDEP and egg mass compared to other groups but feed intake was higher in birds fed 2700 kcal/kg than others. Albumen height and Haugh unit value were higher in hens fed 2800 kcal compared to others but other quality parameters were not affected by dietary treatments. TTAD (total tract apparent digestibility) of crude protein, crude fat and energy were linearly decreased (P>0.05) with increasing energy levels showing lowest value in 3000 kcal/kg. Serum glucose and serum cholesterol values were linearly (P<0.05) increased with increasing levels of dietary ME showing highest value in 3000 kcal/kg. But cholesterol content of yolk and abdominal fat was not affected by dietary energy levels. This study showed that the recommended ME levels (2700 to 2800 kcal/kg) would be appropriate for welfare aviary raised layers in later stage of production and higher levels of dietary ME (over 2800 kcal/kg) could be detrimental for layer performance in welfare aviary. Study 3. Effect of dietary feed additives for extending egg production without forced molting in welfare aviary Forced molting is not allowed according to the guidelines of laying hens welfare. To develop alternative measure to extend the egg production in aged hens, feed additives that could enhance body metabolism were evaluated. Four dietary additives were employed as treatments (T1, no additive control; T2, Medium Chain Fatty Acid + onion extract; T3, Methionine and T4, Lysophospholipid). Seventy four weeks old Lohmann Brown Lite laying hen (n = 640) and cockerels (n = 60) were assigned to 2-tier aviary furnished with adjacent sand bath for 7 weeks. During the experimental period, hen day egg production (HDEP), egg weight, body weight and feed intake were recorded. At the end of experiment, four birds from each treatment were assigned to measure abdominal fat, serum cholesterol and serum glucose level. Egg cholesterol was also analyzed. Cecal content was also collected and analyzed bacterial counts. Treatment-2 showed better HDEP (avg. 68.86%) than other treatments whereas T1 exerted poorest (avg. 62.37%) HDEP. Eggs from T1 were heavier (avg. 65.77g) than other treatments. Both egg weight (avg. 64.76g) and daily feed intake (avg. 113.84g) were lower in T4 hens. Abdominal fat content, serum cholesterol and egg cholesterol concentration in T4 hens were significantly (P<0.05) higher than other groups. Serum cholesterol and egg cholesterol levels in T3 hens were comparatively lower than others. Serum glucose concentration was not different among treatments. Treatment-2 enhanced the colonization of Lactobacillus and slightly reduced the Coliforms in cecal content; however, no Salmonella was detected. The study showed that MCFA with onion extract was the most effective for extending the life of egg production in aged laying hens that were not forced molted. Overall, this study found that i) the welfare housing system can be successfully implimented as a welfare housing production system. ii) ME level for hens in welfare aviary system does not has to be increased as it was hypothesized by considering the increased free locomotory activity of the hens. iii) To extend egg production cycle for aged hens under non-molting welfare bestwed practice, dietary MCFA + onion extract additive supplementation was the best for extending egg production cycle.