Effect of occupancy time on welfare and productivity of broiler chickens E. SOSNÓWKA-CZAJKA*, E. HERBUT and R. MUCHACKA Department of Technology, Ecology and Economics of Animal Production, National Research Institute of Animal Production, 32–083 Balice, Poland *Corresponding author: [email protected] The aim of this study was to determine the effect of occupancy time on behaviour and productivity of broiler chickens. A total of 540 Hubbard broiler chicks were investigated. After weighing and tagging, chicks were allocated to one of 3 groups: I – control – chicks were moved to the broiler house 2 hours after being taken out of the hatcher; II – experimental – chicks were moved to the broiler house 8 hours after being taken out of the hatcher; III – experimental – chicks were moved to the broiler house 14 hours after being taken out of the hatcher. Chicks of all the groups were removed from the hatcher at the same time and transported to an experimental broiler house of the National Research Institute of Animal Production. These procedures lasted for approximately 2 hours. Chicks of groups II and III were exposed until occupancy to cold stress (for 6 and 12 h respectively; ambient temperature 22°C), high stocking density and lack of water and feed, while chicks of group I were placed in a battery of cages (31°C) at a stocking density of 15 birds/m2 and were allowed access to feed and water. Throughout the experiment, individual body weight of the chicks, feed intake and mortality were recorded at 7-day intervals. Until day 21, behavioural observations were made twice a day (morning and evening) and twice a week. The results were analysed statistically using variance analysis. Significant differences were analysed with Duncan’s test and ethological observations with the chisquare test. In group III, the lowest mortality percentage was noted both on days 1-21 and during the entire rearing period. This was probably due to the best utilization of maternal antibodies from the yolk sac, which influenced the health of broiler chickens. Birds of group III were more often scattered than congested, as they were probably characterized by a higher metabolic rate (as confirmed by previous research on acclimatization), higher weight of heart, lower carcass fatness, lower liver weight and better feed conversion. The results obtained indicate that occupancy and feed and water access time from the time when chicks were taken out of the hatcher, did not influence the productive results, while having an effect on the biological quality of the chicks. Key words: broiler chickens; housing time; welfare; productivity

Introduction The poultry sector is characterized by rapid genetic, technological and nutritional advances in relation to the other areas of animal production. This enabled poultry producers to convert from small-scale farms to specialized commercial farms with intensive production. However, the systems in which poultry are kept in large flocks are not always welfare friendly. Sometimes they curb their instincts or normal behaviour patterns, leading to stress, emotional disorders, body disturbances, injuries and diseases (Conraths et al., 2005; Vits et al., 2005 a; Vits et al., 2005 b). Many authors (Jones et al., 2005; Rodenburg et al., 2005; Vits et al., 2005 b) discussing the environmental aspects of poultry rearing have shown that the environment has an effect on the health,

quality and economic parameters. During rearing, birds may be exposed to several unfavourable factors that lead to discomfort and induce stress. Stress reactions are due to transport (Kannan et al., 1997; Abeyesinghe et al., 2001), excessive stocking density, restriction of movement (Martrenchar et al., 1997; Patterson and Singel, 1998; Feddes et al. 2002) and other environmental factors such as inadequate climate (Cooper and Washburn, 1998; Yahav, 2000; Soko8owicz and Herbut, 2001), noise or restricted access to feed and water (Maxwell et al., 1990). Because current lines of high-producing chickens are characterized by relatively low resistance to stress, efforts are made to optimize their rearing by ensuring adequate welfare, i.e. mental and physical comfort (Hughes, 1988). Methods for the evaluation of animal welfare account for behavioural, health and physiological parameters. These methods indirectly serve to evaluate poultry management systems. Duncan and Petherick (1991) report that bird behaviour is a true reflection of its physical and mental state and the most sensitive indicator of stress, and the different behavioural types expressed by the animal reflect its adaptation to the surrounding physical and social environment. Dawkins (1998) understands welfare as a number of mechanisms that strengthen the animal’s condition in response to the environment in which it lives. Birds can also adapt to unfavourable management conditions by modifying their behaviour (Elrom, 2000a). Theoretically, the occupancy time of hatched chicks is of great importance. Therefore, the principles of handling chicks within the first hours of hatching are increasingly applied in poultry practice. This concerns mainly hatchery and broiler house conditions and the duration and conditions of transporting chicks from the hatchery to the broiler house. Newly hatched chicks are exposed to difficult thermal and humidity conditions of the hatcher for approximately 24 hours (Herbut et al., 1993). This time is increased by sorting, i.e. bird selection, vaccination, preparation for transport and transport itself (Pietras et al., 1990). These procedures may induce stress reactions related mainly to social and thermal conditions at that time. The aim of the present study was to determine the effect of occupancy time on the behaviour and productivity of broiler chickens.

Material and methods A total of 540 Hubbard broiler chicks were investigated. After weighing and tagging, chicks were allocated to one of 3 groups: I – control – chicks were moved to the broiler house 2 hours after being taken out of the hatcher; II – experimental – chicks were moved to the broiler house 8 hours after being taken out of the hatcher; III – experimental – chicks were moved to the broiler house 14 hours after being taken out of the hatcher. Chicks of all the groups were removed from the hatcher at the same time and transported to an experimental broiler house of the National Research Institute of Animal Production. These procedures lasted for approximately 2 hours. Chicks of groups II and III were exposed until occupancy to cold stress (for 6 and 12 h respectively; ambient temperature 22°C), high stocking density and lack of water and feed, while chicks of group I were placed in a battery of cages (31°C) at a stocking density of 15 birds/m2 and were allowed access to feed and water. Chicks were reared in batteries of cages at a stocking density of 15 birds/m2 and were fed ad libitum with concentrate-based standard diets. Throughout the experiment, individual body weight of the chicks, feed intake and mortality were recorded once a week. Until day 21, behavioural observations were made twice a week in the morning and evening. At 42 days of rearing, 20 chickens (pullets and cockerels) of medium body weight were selected from each group. After slaughter and cooling to 4°C for 24 h, they were subjected to a simplified slaughter analysis. The results were analysed statistically using variance analysis. Significant differences were analysed with Duncan’s test and ethological observations with the chi-square test.

Results and discussion According to Elrom (2000b), acute or chronic stress causes changes in metabolism, especially in young birds, as reflected in the inhibition of bone growth and loss of weight despite increased feed intake. Chicks from group III were characterized by the lowest body weight at 1 and 7 days of rearing and these

differences resulted from the time at which the chicks were moved to the broiler house and from the access to feed and water (Tab. 1). Growth compensation occurred later into the rearing period and there were no differences in the body weight of chickens between the analysed groups. Growth compensation in chicks on restricted feeding was also reported by Lippens et al. (2000). Table 1. Body weight of broiler chickens (g) – x±SE Days of growth 1 7 14 21 28 35 42

I 41.54 ± 0.28a 149.08 ± 1.08a 400.84 ± 3.10 714.81 ± 4.85 1280.65 ± 8.99 1848.94 ± 15.08 2412.80 ± 20.56

Group II 41.18 ± 0.29 148.84 ± 1.44a 404.51 ± 3.73 711.77 ± 5.13 1281.52 ± 10.44 1846.84 ± 16.49 2401.33 ± 23.46

III 40.23 ± 0.26b 143.28 ± 0.98b 394.84 ± 2.30 720.95 ± 4.62 1288.67 ± 8.90 1855.13 ± 14.76 2419.68 ± 22.26

A,B – values in rows with different letters differ highly significantly (pH0.01) a,b – values in rows with different letters differ significantly (pH0.05)

Group III was characterized by the best feed conversion during the first three weeks of rearing (Tab. 2). Other authors confirm that restricted feeding in the initial period of growth results in better feed conversion, with no losses in the final body weight (Plavnik and Hurwitz, 1991; Deaton, 1995; Zubair and Leeson, 1996; Cristofori et al., 1997). Table 2. Feed conversion (g) per 1 kg weight gain– x±SE Days of growth 1–7 8 – 14 15 – 21 22 – 28 29 – 35 36 – 42

I 900 ± 20.0a 1320 ± 10.0 1770 ± 40.0 1530 ± 30.0 1900 ± 40.0 2120 ± 50.0

Group II 860 ± 20.0 1330 ± 10.0 1790 ± 40.0a 1500 ± 30.0 1930 ± 40.0 2080 ± 50.0

III 830 ± 20.0b 1350 ± 10.0 1680 ± 40.0b 1530 ± 30.0 1990 ± 40.0 2090 ± 50.0

1 – 21 22 – 42 1 – 42

1430 ± 10.0a 1840 ± 20.0 1720 ± 10.0

1430 ± 10.0a 1830 ± 20.0 1700 ± 10.0

1390 ± 10.0b 1850 ± 20.0 1710 ± 10.0

For explanations see Table 1 Table 3. Chicken mortality (%) Days of growth 1 – 21 22 – 42 1 – 42

I 2.42 2.42 4.84

Group II 2.42 2.42 4.84

III 1.20 1.81 3.01

Chou et al. (2004) reported that the distance between hatchery and broiler house is decisive for broiler mortality. For each kilometre increase in the distance between hatchery and broiler house, chick mortality increased by 0.05%. These authors also found that not only the duration of shipping but also the route is important. Broiler chicks transported via mountain routes showed an almost 10% increase in mortality compared to delivery via flat terrain. However, in our study we found no mortality during transport or directly before chicks were moved to batteries of cages. The use of restricted feeding in the first days of rearing reduced broiler mortality during the entire rearing period (Robinson et al., 1992; Saleh et al., 1996). Group III was characterized by the lowest percentage mortality from 1 to 21 days and during the entire rearing period (Tab. 3). This was probably due to the best utilization of maternal antibodies from the yolk sac, which had an effect on broiler health. Likewise, Lippens et al. (2000) reported that restricted feeding in

the first days of rearing reduced mortality. According to Chou et al. (2004), however, increased stocking density is parallel to a considerable increase in chick mortality during the first days of life, and also inadequate climatic conditions (temperature and ventilation) cause a significant increase in mortality. Table 4. Behaviour of chickens (%) Eating

Week of growth

Drinking

Congested

Scattered

Morning 1 Afternoon

I 5.63 6.67A

II 4.81 7.778

III 4.44 11.67B

I 1.30a 2.96

II 3.33b 2.96

Group III I 3.07b 56.67 5.19 50.56

2

Morning Afternoon

11.82 5.45a

9.09 10.61b

8.18 9.39

3.64 1.21

3.94 2.42

2.12 3.03

18.00 18.00

22.58 23.15a

15.14 9.14b

82.00 82.00

77.42 76.85a

84.86 90.86b

3

Morning Afternoon

14.24 6.36a

10.30 10.30

9.09 12.42b

2.42 1.21A

1.82a 3.33

4.85b 4.85B

22.65a 44.12

10.00b 36.47

10.59b 34.12

77.35a 55.88

90.00b 63.53

89.41b 65.88

II 60.00 54.17a

III 57.50 34.17b

I 43.33 49.44

II 40.00 45.83a

III 42.50 65.83b

For explanations see Table 1 Table 5. Results of carcass dissection (%) for 42-day-old broilers– x±SE Item Dressing percentage: with giblets without giblets Breast muscles

L

Group I x

M

L

Group II x

M

L

Group III x

M

73.38±0.74 73.59±0.52a 73.80±0.74 74.77±0.74 75.08±0.52b 75.40±0.74 75.33±0.74 74.60±0.52 73.88±0.74 69.88±0.73a 70.07±0.51a 70.26±0.73 71.38±0.73 71.68±0.51b 71.98±0.73b 71.42±0.73 70.96±0.51 70.51±0.73 22.98±0.40 22.56±0.30 22.15±0.40a 23.63±0.40b 23.00±0.30 22.36±0.40a 22.52±0.40 22.72±0.30 22.92±0.40

Leg muscles 20.73±0.69 21.05±0.48 21.38±0.69 21.47±0.69 Leg bones 5.00±0.20Bc 5.47±0.15 5.94±0.20Aa 5.35±0.20bc Abdominal 3.48±0.19Cc 2.93±0.16 2.38±0.19Aa 2.98±0.19bc fat Giblets 4.78±0.14 4.78±0.10 4.79±0.14 4.55±0.14 Liver 2.87±0.11b 2.84±0.08 2.82±0.11 2.55±0.11a Gizzard 1.20±0.07 1.20±0.05 1.19±0.07 1.20±0.07 Heart 0.68±0.04Aa 0.70±0.03 0.72±0.04a 0.70±0.04a

21.68±0.48 21.90±0.69 21.18±0.69 21.11±0.48 21.03±0.69 5.49±0.15 5.63±0.20ab 5.57±0.20ab 5.58±0.15 5.59±0.20ab 2.67±0.16 2.35±0.19Aa 3.11±0.19BCbc 2.85±0.16 2.58±0.19ABab 4.54±0.10 2.65±0.08 1.14±0.05 0.71±0.03

4.53±0.14 4.76±0.14 2.75±0.11 2.85±0.11 1.08±0.07 1.19±0.07 0.71±0.04a 0.70±0.04a

4.66±0.10 4.57±0.14 2.71±0.08 2.56±0.11 1.19±0.05 1.19±0.07 0.76±0.03 0.82±0.04Bb

For explanations see Table 1

According to Pettit-Riley and Estevez (2001), Sanotra et al. (2002) and Appleby (2004), stocking density determines the behaviour of broiler chickens. However, Dawkins et al. (2004) state that climatic conditions affect bird behaviour to a greater degree than stocking density. Degen and Spinu (2003) believe that not only stocking density but also temperature are decisive for the behavioral patterns of birds. Restricted access to feed and water modifies the behaviour of birds (Haskel et al., 2004). According to Elrom (2000c), the duration and conditions of shipping chicks from hatchery to rearing house caused changes in behaviour, mainly by increasing the timidity of birds in the later period of rearing, which had an effect on later behavioural changes, reduced rearing performance and increased economic losses. In our study, we did not observe increased timidity in birds exposed to stress factors. However, we found greater frequency of eating and drinking in birds that occupied the broiler house 14 h after hatching (Tab. 4). Birds from group III were more often scattered than congested as they were probably characterized by more rapid metabolism, as confirmed by our earlier studies on acclimation (Sosnówka-Czajka and Herbut, 2001; Sosnówka-Czajka and Herbut, 2003), higher cardiac weight, lower carcass fatness and lower carcass

fatness (Tab. 5) and better feed conversion in the first period of rearing. According to Saylam and Turan (2004), restricted feeding determines the weights of heart, liver, gizzard and abdominal fat. Studies by other authors confirmed that restricted feeding in the initial period of rearing is associated with lower fatness (Plavnik and Hurwitz, 1991; Deaton, 1995). The results obtained suggest that the biological quality of chicks rather than occupancy time and access time to feed and water from the time when chicks are taken out of the hatcher have a significant effect on productive results. The main factor involved is probably the level of immunity transmitted by the mother and the possibility of a chick using it from the yolk sac. In this case, the lack of access to feed during the first hours after hatching stimulated the chick body to maximize the use of yolk sac resources, which contributed to satisfactory productive results and very good health later into the rearing period.

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