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Effects of post-hatch brooding temperature on performance of starter and growing Pekin ducks
Effects of post-hatch brooding temperature on performance of starter and growing Pekin ducks M. Xie,∗ P. X. Sun,∗ Y. L. Feng,∗,† Y. Jiang,‡ J. Tang,∗ W. Huang,∗ Q. Zhang,∗ and S. S. Hou∗,1 Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China; † Guizhou Animal Husbandry and Veterinary Research Institute, Guizhou Academy of Agricultural Sciences, Guiyang, Guizhou 550000, China; and ‡ College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China ABSTRACT An experiment was conducted to investigate the effects of post-hatch brooding temperature on the growth performance of starter Pekin ducks from hatch to 14 D of age and the subsequent growth performance and carcass trait of growing ducks from 15 to 42 D of age. A total of 360 one-day-old male White Pekin ducks were allocated randomly to 6 environmentcontrolled chambers with ambient temperature set at 26, 28, 30, 32, 34, and 36◦ C from hatch to 7 D of age, respectively, and then decreased gradually to 26◦ C at 14 D of age. At 14 D of age, all ducks from all chambers were transferred to a duck barn with ambient temperature maintaining from 26 to 22◦ C and these birds continued to be raised from 14 to 42 D of age. At 14 D of age, body weight, weight gain, and feed intake decreased linearly or quadratically as initial brooding temperature increased (P < 0.05) and these performance traits were reduced when initial brood-
ing temperature increased to 36◦ C (P < 0.05). There was no difference in growth performance between ducks fed at brooding temperature regimen starting at 26, 28, 30, and 32◦ C (P > 0.05). According to broken-line regression, the upper critical temperatures of the initial brooding temperature during the starter period for body weight, weight gain, and feed intake were 31.3, 31.3, and 31.1◦ C, respectively. On the other hand, the growing ducks brooded initially at 26 or 36◦ C had lower body weight, weight gain, and feed intake as compared to other birds brooded starting from 28 to 34◦ C (P < 0.05), but the initial brooding temperature had no effects on carcass traits (P > 0.05). It was concluded that the upper critical temperature of the initial brooding temperature for starter Pekin ducks was 31.3◦ C and too low initial brooding temperature could lead to growth depression during the subsequent growing period.
Key words: ducks, brooding temperature, performance 2019 Poultry Science 98:3647–3651 http://dx.doi.org/10.3382/ps/pez203
INTRODUCTION Temperature is an important environmental factor for poultry management and production. Initial brooding temperature is critical for post-hatch development of starter poultry. Broilers did not maintain normal body temperature without external heat source until about 10 D of age (Nichelmann and Tzschentke, 2002). Too low brooding temperatures could reduce broiler growth compared to normal brooding temperatures (Renwick and Washburn, 1982; Scott and Washburn, 1985; Deaton et al., 1996; Bruzual et al., 2000; Leksrisompong et al., 2009). Furthermore, although brooding temperature could not influence the subsequent performance of growing broilers, the growing birds brooded at low temperature had higher total C 2019 Poultry Science Association Inc. Received December 6, 2018. Accepted April 23, 2019. 1 Corresponding author: [email protected]
mortality and the mortality due to ascites compared to those brooded at high temperature (Deaton et al., 1996). At present, commercial duck production increases more rapidly than before but the information on the temperature requirement for modern duck production is not clear until now. Although Wilson et al. (1980) examined the effects of high environmental temperature on performance traits of White Pekin ducks, the requirement of brooding temperature for starter Pekin ducks was not provided by them. In fact, there existed a large variation of brooding temperature in commercial duck production. On commercial duck farms in the UK, the average weekly temperature fell from 25.4◦ C in week 1 during brooding to an average 11.3◦ C in winter and 19.5◦ C in summer during growing (weeks 3 to 7) period (Jones and Dawkins, 2010). In commercial duck houses of the U.S., the average ambient temperatures at day 7, 21, and 32 post-hatch were 25 to 27, 26 to 27, and 25 to 26◦ C in summer and 20 to 23, 14 to 16, 12 to 17◦ C in winter, respectively (Fraley et al., 2013; Karcher et al., 2013). In China,
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Table 1. Brooding temperature regimens from hatch to 14 D of age of experimental treatments. Brooding temperature (◦ C) Treatment
8D
9D
10 D
11 D
12 D
13 D
14 D
26 28 30 32 34 36
26 28 30 32 34 36
26 28 30 32 34 34
26 28 30 32 32 32
26 28 30 30 30 30
26 28 28 28 28 28
26 26 26 26 26 26
26 26 26 26 26 26
the ambient temperature of duck house was kept at 33◦ C from 1 to 3 D of age and then it was reduced to approximately 25◦ C until 14 D of age and was kept at approximately 16 to 22◦ C thereafter (Xie et al., 2014). Therefore, the objective of our study was to evaluate the effects of brooding temperature on the performance of starter and growing Pekin ducks and discuss the temperature requirements for brooding ducks.
MATERIALS AND METHODS All procedures of our experiments were approved by the animal care and use committee of Institute of Animal Sciences of Chinese Academy of Agricultural Sciences (Beijing, China). All ducks were raised in environment-controlled chambers. Each chamber has similar space size and it had 6 raised wire-floor pens with the same size (0.8 × 0.8 m) in it. In order to reduce the difference in pen placement and indoor environment among all chambers, all chambers had the same pen location and distribution of lighting and ventilation. In each chamber, all ducks were reared in raised wire-floor pens and fed with commercial standard starter diets containing 2,900 kcal metabolic energy/kg and 20% crude protein. Lighting was continuous and all ducks had free access to water and feed. Water was provided by drip-nipple water supply lines and feed was fed in pellet form. In our study, initial ambient temperatures from hatch to 7 D of age were set at 26, 28, 30, 32, 34, and 36◦ C for corresponding chambers and the ambient temperature of all chambers decreased gradually to 26◦ C until 14 D of age according to temperature regimens shown in Table 1. The relative humidity of all chambers was set at 60% during the starter period from hatch to 14 D of age. A total of 360 one-day-old male White Pekin ducks from a commercial hatchery were allocated randomly to 6 environment-controlled chambers with different ambient temperatures. In each chamber, 60 birds were divided randomly into 6 raised wire-floor pens of 10 birds and all pens had similar initial body weight at the start of experiment. At 14 D of age, all ducks from all chambers were transferred to a duck barn with ambient temperature maintaining from 26 to 22◦ C from 14 to 42 D of age. In this barn, all ducks were still reared in raised wire-floor pens according to corresponding brooding temperature treatments and fed with commercial standard growing diets containing 3,000 kcal metabolic energy/kg and 18.0% crude protein. During this period,
lighting was continuous and all ducks had free access to water and feed. Water was also provided by drip-nipple water supply lines and feed was fed in pellet form. At 14 and 42 D of age, body weight gain, feed intake, and feed/gain of ducks from each pen were measured. Feed intake and feed/gain were all corrected for mortality. At 42 D of age, after 12 h feed deprivation, 2 ducks were randomly selected from each pen and were stunned electrically and then killed immediately by neck cut and eviscerated manually. Abdominal fat, breast meat (including pectoralis major and pectoralis minor), and leg meat (including thigh and drum stick) were all removed manually from carcasses and weighed and percentages relative to live body weight at processing were also calculated. Breast and leg meat were all skinless and boneless. Data were analyzed as a completely randomized design using the 1-way ANOVA procedure of SAS (SAS Institute, 2003), with pen used as the experimental unit for analysis. When treatment effect was significant (P < 0.05), means were compared by using Tukey’s multiple comparison procedure of SAS (SAS Institute, 2003). The linear and quadratic polynomial contrasts were also performed to determine the effects of temperature treatment on duck performance. The variability in the data was expressed as the standard error of the means (SEM) and a probability level of P < 0.05 was considered to be statistically significant. In our study, the upper critical temperature of initial brooding temperature was estimated by brokenline regression (Huynh et al., 2005). The upper critical temperature was the inflection point temperature above which the growth response of ducks started to change. The broken-line model was provided as follows:
y = l + u (x − r ) where y = growth response (body weight, weight gain or feed intake), x = ambient temperature (◦ C), r = the upper critical temperature (◦ C), u = the slope of the curve, l = maximum response if x < r and y = l + u (x − r) if x ≥ r.
RESULTS AND DISCUSSION In our study, the mortality was very low. Only 3 and 2 ducks died during the starter and growing period, respectively, and these dead birds come from different
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1 2 3 4 5 6
1 to 7 D
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BROODING TEMPERATURE IN DUCKS Table 2. Effects of brooding temperature on growth performance of starter Pekin ducks from hatch to 2 wk of age.1 Brooding temperature (◦ C) Week 2
26 28 30 32 34 36 SEM
26 28 30 32 34 36
Probability Temperature Temperature linear Temperature quadratic 1
to to to to to
26 26 26 26 26
Body weight (g/bird)
Weight gain (g/bird/day)
716.4a,b 733.0a 711.9a,b 695.2a,b 677.0b 602.3c 11.66
47.3a,b 48.4a 46.9a,b 45.7a,b 44.4b 39.1c 0.83
< 0.0001 0.0264 0.0072
< 0.0001 0.0246 0.0070
Feed intake (g/bird/day) 67.9a 68.4a 66.3a 63.7a 63.6a 54.1b 1.18 < 0.0001 0.0226 0.0239
Feed/gain (g/g) 1.44 1.41 1.41 1.39 1.43 1.39 0.013 0.0712 0.2583 0.4982
Results are means with n = 6 per treatment. Means with different superscripts within the same column differ significantly (P < 0.05).
a–c
Figure 1. Fitted broken-line plot of 2-wk-old body weight as a function of initial brooding temperature. Broken-line equation is y = 720.4–23.2 × (x –31.3), y = 720.4 when x < 31.3◦ C. 95% CI = 95% confidence interval of the breakpoint.
temperature treatments. Therefore, the mortality could not affect the accuracy of our study. The effects of brooding temperature on growth performance of starter Pekin ducks were shown in Table 2. Body weight, weight gain, and feed intake decreased linearly or quadratically as the initial brooding temperature increased (P < 0.05), and these performance traits were reduced when the initial brooding temperature increased to 36◦ C (P < 0.05). Our results were partly supported by Wilson et al. (1980), who found that Pekin ducks had higher 2- and 3-wk-old body weight at 25.5◦ C than at 29.4◦ C. However, there was no difference in body weight, weight gain, and feed intake between ducks fed at the brooding temperature regimen starting at 26, 28, 30, and 32◦ C (P > 0.05, Table 2), which indicated that there existed a temperature plateau and the upper critical temperature for duck growth and the growth response would be reduced when the temperature went beyond the upper critical temperature. Therefore, based on the growth performance at 14 D of age, the upper critical temperature of initial brooding temperature of starter ducks was estimated by brokenline regression. According to this regression, the upper critical temperatures of the initial brooding temperature during the starter period for body weight (Figure 1), weight gain (Figure 2), and feed intake (Figure 3) were 31.3, 31.3, and 31.1◦ C, respectively. Our results
Figure 2. Fitted broken-line plot of 0- to 2-wk weight gain as a function of initial brooding temperature. Broken-line equation is y = 47.5–1.65 × (x –31.3), y = 47.5 when x < 31.3◦ C. 95% CI = 95% confidence interval of the breakpoint.
Figure 3. Fitted broken-line plot of 0- to 2-wk feed intake as a function of initial brooding temperature. Broken-line equation is y = 67.5–2.40 × (x –31.1), y = 67.5 when x < 31.1◦ C. 95% CI = 95% confidence interval of the breakpoint.
showed that the initial brooding temperature should not be above 32◦ C. Recently, a 26.5 to 29.5◦ C ambient temperature was suggested to be the minimum initial ambient temperature for brooding ducklings (FASS, 2010), and it was supported by our results in which the ducks brooded at 32◦ C initially had the growth performance similar to the birds brooded at 26◦ C initially (P > 0.05, Table 2). However, the broiler results were different from ours in ducks. The chicks brooded in the temperature regimen starting at 26.7◦ C had lower body weight and higher feed/gain at 3 wk of age than the birds brooded at higher temperature regimen starting at 35, 32.2, and 29.4◦ C (Deaton et al., 1996).
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Table 3. Effects of brooding temperature on subsequent growth performance of growing Pekin ducks from 2 to 6 wk of age.1 Temperature (◦ C) Week 2
26 28 30 32 34 36 SEM
26 28 30 32 34 36
to to to to to
26 26 26 26 26
Probability Temperature Temperature linear Temperature quadratic 1
Body weight (g/bird) 3055.6b 3165.5a 3173.4a 3235.2a 3207.0a 3012.1b 35.15 0.0008 0.9186 0.0568
Weight gain (g/bird/day)
Feed intake (g/bird/day)
Feed/gain (g/g)
83.5c 86.9a,b,c 87.9a,b 90.7a 90.4a 86.1b,c 1.28
234.0b 247.3a 241.0a,b 250.4a 250.9a 232.2b 3.93
2.80 2.85 2.74 2.76 2.78 2.70 0.032
0.0047 0.2945 0.0419
0.0057 0.8907 0.2257
0.0544 0.1099 0.3251
Results are means with n = 6 per treatment. Means with different superscripts within the same column differ significantly (P < 0.05).
a–c
Table 4. Effects of brooding temperature on subsequent carcass traits of 42-day-old growing Pekin ducks.1 Temperature (◦ C) Week 1
Week 2
Carcass (%)
26 28 30 32 34 36 SEM
26 28 30 32 34 36
67.6 67.8 67.4 67.8 67.2 66.7 0.64
to to to to to
26 26 26 26 26
Probability Temperature Temperature linear Temperature quadratic 1
0.8623 0.0871 0.0844
Breast meat (%)
Leg meat (%)
Abdominal fat (%)
7.31 7.63 8.47 7.70 7.57 7.21 0.480
8.12 7.68 8.14 8.09 8.35 8.46 0.222
1.90 1.87 1.84 1.82 1.80 1.79 0.088
0.5148 0.7415 0.1921
0.2130 0.1009 0.2022
0.9428 0.0003 < 0.0001
Results are means with n = 6 per treatment.
On the other hand, the effects of brooding temperature on subsequent growth performance and carcass traits of ducks during the growing period were shown in Tables 3 and 4. The initial brooding temperature could affect the growth performance of growing ducks (P < 0.05), but it had no effects on carcass traits (P > 0.05). The growing ducks brooded initially at 26 or 36◦ C had lower body weight, weight gain, and feed intake compared to other birds brooded starting from 28 to 34◦ C (P < 0.05). The growth depression of growing ducks brooded at 26 or 36◦ C may be due to the reduction of feed intake and weight gain during the growing period (P < 0.05, Table 3). Our results suggested that too high and low brooding temperature had negative effects on duck performance during the subsequent growing period, although the ducks brooded at 26◦ C had the performance similar to the birds brooded at higher temperature during the starter period. In broilers, the brooding temperature from 26.7 to 35◦ C had no significant effects on the subsequent performance during growing period (Harris et al., 1975; Deaton et al., 1996). However, during the growing period, high mortality took place in broilers brooded at low temperature and some mortality was due to ascites (Deaton et al., 1996). Although our study had
too low mortality in growing ducks, it was cautious that low brooding temperature could lead to ascites. In conclusion, too high and low brooding temperature could have negative effects on the performance of starter and growing Pekin ducks. According to the broken-line regression based on starter growth performance, the upper critical temperature of initial brooding temperature during the starter period was 31.3◦ C and too low initial brooding temperature could lead to growth depression during the subsequent growing period.
ACKNOWLEDGMENTS This work was sponsored by the earmarked fund for National Key Research & Development Program of China (2016YFD0500509) and China Agriculture Research System (CARS-42).
REFERENCES Bruzual, J. J., S. D. Peak, J. Brake, and E. D. Peebles. 2000. Effects of relative humidity during the last five days of incubation and brooding temperature on performance of broiler chicks from young broiler breeders. Poult. Sci. 79:1385–1391.
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pine shaving litter on environment and Pekin duck condition. Poult. Sci. 92:583–590. Leksrisompong, N., H. Romero-Sanchez, P. W. Plumstead, K. E. Brannan, S. Yahav, and J. Brake. 2009. Broiler incubation. 2. Interaction of incubation and brooding temperatures on broiler chick feed consumption and growth. Poult. Sci. 88:1321–1329. Nichelmann, M., and B. Tzschentke. 2002. Ontogeny of thermoregulation in precocial birds. Comp. Biochem. Physiol. - A Mol. Integr. Physiol. 131:751–763. Renwick, G. M., and K. W. Washburn. 1982. Adaptation of chickens to cool temperature brooding. Poult. Sci. 61:1279–1289. SAS Institute. 2003. SAS User’s Guide: Statistics. Version 9.0. SAS Institute, Inc., Cary, NC. Scott, T. R., and K. W. Washburn. 1985. Evaluation of growth, hormonal, and hematological responses of neonatal chickens to reduced temperature brooding. Poult. Sci. 64:777–784. Wilson, E. K., F. W. Pierson, P. Y. Hester, R. L. Adams, and W. J. Stadelman. 1980. The effects of high environmental temperature on feed passage time and performance traits of White Pekin ducks. Poult. Sci. 59:2322–2330. Xie, M., Y. Jiang, J. Tang, Z. G. Wen, W Huang, and S. S. Hou. 2014. Effects of stocking density on growth performance, carcass traits, and foot pad lesions of White Pekin ducks. Poult. Sci. 93:1644–1648.
Downloaded from https://academic.oup.com/ps/article-abstract/98/9/3647/5486567 by Stockholm University Library user on 20 August 2019
Deaton, J. W., S. L. Branton, J. D. Simmons, and B. D. Lott. 1996. The effect of brooding temperature on broiler performance. Poult. Sci. 75:1217–1220. FASS (Federation of Animal Science Societies). 2010. Pages 116–117 Guide for the Care and Use of Animals in Agricultural Research and Teaching. 3rd rev. ed. Fed. Anim. Sci. Soc., Champaign, IL. Fraley, S. M., G. S. Fraley, D. M. Karcher, M. M. Makagon, and M. S. Lilburn. 2013. Influence of plastic slatted floors compared with pine shaving litter on Pekin duck condition during the summer months. Poult. Sci. 92:1706–1711. Harris, G. C., Jr., G. S. Nelson, W. H. Dodgen, and R. L. Seay. 1975. The influence of air temperature during brooding on broiler performance. Poult. Sci. 54:571–577. Huynh, T. T. T., A. J. A. Aarnink, M. W. A. Verstegen, W. J. J. Gerrits, M. J. W. Heetkamp, B. Kemp, and T. T. Canh. 2005. Effects of increasing temperatures on physiological changes in pigs at different relative humidities. J. Anim. Sci. 83: 1385–1396. Jones, T. A., and M. S. Dawkins. 2010. Environment and management factors affecting Pekin duck production and welfare on commercial farms in the UK. Br. Poult. Sci. 51:12–21. Karcher, D. M., M. M. Makagon, G. S. Fraley, S. M. Fraley, and M. S. Lilburn. 2013. Influence of raised plastic floors compared with
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ing temperature increased to 36◦ C (P < 0.05). There was no difference in growth performance between ducks fed at brooding temperature regimen starting at 26, 28, 30, and 32◦ C (P > 0.05). According to broken-line regression, the upper critical temperatures of the initial brooding temperature during the starter period for body weight, weight gain, and feed intake were 31.3, 31.3, and 31.1◦ C, respectively. On the other hand, the growing ducks brooded initially at 26 or 36◦ C had lower body weight, weight gain, and feed intake as compared to other birds brooded starting from 28 to 34◦ C (P < 0.05), but the initial brooding temperature had no effects on carcass traits (P > 0.05). It was concluded that the upper critical temperature of the initial brooding temperature for starter Pekin ducks was 31.3◦ C and too low initial brooding temperature could lead to growth depression during the subsequent growing period.
Key words: ducks, brooding temperature, performance 2019 Poultry Science 98:3647–3651 http://dx.doi.org/10.3382/ps/pez203
INTRODUCTION Temperature is an important environmental factor for poultry management and production. Initial brooding temperature is critical for post-hatch development of starter poultry. Broilers did not maintain normal body temperature without external heat source until about 10 D of age (Nichelmann and Tzschentke, 2002). Too low brooding temperatures could reduce broiler growth compared to normal brooding temperatures (Renwick and Washburn, 1982; Scott and Washburn, 1985; Deaton et al., 1996; Bruzual et al., 2000; Leksrisompong et al., 2009). Furthermore, although brooding temperature could not influence the subsequent performance of growing broilers, the growing birds brooded at low temperature had higher total C 2019 Poultry Science Association Inc. Received December 6, 2018. Accepted April 23, 2019. 1 Corresponding author: [email protected]
mortality and the mortality due to ascites compared to those brooded at high temperature (Deaton et al., 1996). At present, commercial duck production increases more rapidly than before but the information on the temperature requirement for modern duck production is not clear until now. Although Wilson et al. (1980) examined the effects of high environmental temperature on performance traits of White Pekin ducks, the requirement of brooding temperature for starter Pekin ducks was not provided by them. In fact, there existed a large variation of brooding temperature in commercial duck production. On commercial duck farms in the UK, the average weekly temperature fell from 25.4◦ C in week 1 during brooding to an average 11.3◦ C in winter and 19.5◦ C in summer during growing (weeks 3 to 7) period (Jones and Dawkins, 2010). In commercial duck houses of the U.S., the average ambient temperatures at day 7, 21, and 32 post-hatch were 25 to 27, 26 to 27, and 25 to 26◦ C in summer and 20 to 23, 14 to 16, 12 to 17◦ C in winter, respectively (Fraley et al., 2013; Karcher et al., 2013). In China,
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Table 1. Brooding temperature regimens from hatch to 14 D of age of experimental treatments. Brooding temperature (◦ C) Treatment
8D
9D
10 D
11 D
12 D
13 D
14 D
26 28 30 32 34 36
26 28 30 32 34 36
26 28 30 32 34 34
26 28 30 32 32 32
26 28 30 30 30 30
26 28 28 28 28 28
26 26 26 26 26 26
26 26 26 26 26 26
the ambient temperature of duck house was kept at 33◦ C from 1 to 3 D of age and then it was reduced to approximately 25◦ C until 14 D of age and was kept at approximately 16 to 22◦ C thereafter (Xie et al., 2014). Therefore, the objective of our study was to evaluate the effects of brooding temperature on the performance of starter and growing Pekin ducks and discuss the temperature requirements for brooding ducks.
MATERIALS AND METHODS All procedures of our experiments were approved by the animal care and use committee of Institute of Animal Sciences of Chinese Academy of Agricultural Sciences (Beijing, China). All ducks were raised in environment-controlled chambers. Each chamber has similar space size and it had 6 raised wire-floor pens with the same size (0.8 × 0.8 m) in it. In order to reduce the difference in pen placement and indoor environment among all chambers, all chambers had the same pen location and distribution of lighting and ventilation. In each chamber, all ducks were reared in raised wire-floor pens and fed with commercial standard starter diets containing 2,900 kcal metabolic energy/kg and 20% crude protein. Lighting was continuous and all ducks had free access to water and feed. Water was provided by drip-nipple water supply lines and feed was fed in pellet form. In our study, initial ambient temperatures from hatch to 7 D of age were set at 26, 28, 30, 32, 34, and 36◦ C for corresponding chambers and the ambient temperature of all chambers decreased gradually to 26◦ C until 14 D of age according to temperature regimens shown in Table 1. The relative humidity of all chambers was set at 60% during the starter period from hatch to 14 D of age. A total of 360 one-day-old male White Pekin ducks from a commercial hatchery were allocated randomly to 6 environment-controlled chambers with different ambient temperatures. In each chamber, 60 birds were divided randomly into 6 raised wire-floor pens of 10 birds and all pens had similar initial body weight at the start of experiment. At 14 D of age, all ducks from all chambers were transferred to a duck barn with ambient temperature maintaining from 26 to 22◦ C from 14 to 42 D of age. In this barn, all ducks were still reared in raised wire-floor pens according to corresponding brooding temperature treatments and fed with commercial standard growing diets containing 3,000 kcal metabolic energy/kg and 18.0% crude protein. During this period,
lighting was continuous and all ducks had free access to water and feed. Water was also provided by drip-nipple water supply lines and feed was fed in pellet form. At 14 and 42 D of age, body weight gain, feed intake, and feed/gain of ducks from each pen were measured. Feed intake and feed/gain were all corrected for mortality. At 42 D of age, after 12 h feed deprivation, 2 ducks were randomly selected from each pen and were stunned electrically and then killed immediately by neck cut and eviscerated manually. Abdominal fat, breast meat (including pectoralis major and pectoralis minor), and leg meat (including thigh and drum stick) were all removed manually from carcasses and weighed and percentages relative to live body weight at processing were also calculated. Breast and leg meat were all skinless and boneless. Data were analyzed as a completely randomized design using the 1-way ANOVA procedure of SAS (SAS Institute, 2003), with pen used as the experimental unit for analysis. When treatment effect was significant (P < 0.05), means were compared by using Tukey’s multiple comparison procedure of SAS (SAS Institute, 2003). The linear and quadratic polynomial contrasts were also performed to determine the effects of temperature treatment on duck performance. The variability in the data was expressed as the standard error of the means (SEM) and a probability level of P < 0.05 was considered to be statistically significant. In our study, the upper critical temperature of initial brooding temperature was estimated by brokenline regression (Huynh et al., 2005). The upper critical temperature was the inflection point temperature above which the growth response of ducks started to change. The broken-line model was provided as follows:
y = l + u (x − r ) where y = growth response (body weight, weight gain or feed intake), x = ambient temperature (◦ C), r = the upper critical temperature (◦ C), u = the slope of the curve, l = maximum response if x < r and y = l + u (x − r) if x ≥ r.
RESULTS AND DISCUSSION In our study, the mortality was very low. Only 3 and 2 ducks died during the starter and growing period, respectively, and these dead birds come from different
Downloaded from https://academic.oup.com/ps/article-abstract/98/9/3647/5486567 by Stockholm University Library user on 20 August 2019
1 2 3 4 5 6
1 to 7 D
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BROODING TEMPERATURE IN DUCKS Table 2. Effects of brooding temperature on growth performance of starter Pekin ducks from hatch to 2 wk of age.1 Brooding temperature (◦ C) Week 2
26 28 30 32 34 36 SEM
26 28 30 32 34 36
Probability Temperature Temperature linear Temperature quadratic 1
to to to to to
26 26 26 26 26
Body weight (g/bird)
Weight gain (g/bird/day)
716.4a,b 733.0a 711.9a,b 695.2a,b 677.0b 602.3c 11.66
47.3a,b 48.4a 46.9a,b 45.7a,b 44.4b 39.1c 0.83
< 0.0001 0.0264 0.0072
< 0.0001 0.0246 0.0070
Feed intake (g/bird/day) 67.9a 68.4a 66.3a 63.7a 63.6a 54.1b 1.18 < 0.0001 0.0226 0.0239
Feed/gain (g/g) 1.44 1.41 1.41 1.39 1.43 1.39 0.013 0.0712 0.2583 0.4982
Results are means with n = 6 per treatment. Means with different superscripts within the same column differ significantly (P < 0.05).
a–c
Figure 1. Fitted broken-line plot of 2-wk-old body weight as a function of initial brooding temperature. Broken-line equation is y = 720.4–23.2 × (x –31.3), y = 720.4 when x < 31.3◦ C. 95% CI = 95% confidence interval of the breakpoint.
temperature treatments. Therefore, the mortality could not affect the accuracy of our study. The effects of brooding temperature on growth performance of starter Pekin ducks were shown in Table 2. Body weight, weight gain, and feed intake decreased linearly or quadratically as the initial brooding temperature increased (P < 0.05), and these performance traits were reduced when the initial brooding temperature increased to 36◦ C (P < 0.05). Our results were partly supported by Wilson et al. (1980), who found that Pekin ducks had higher 2- and 3-wk-old body weight at 25.5◦ C than at 29.4◦ C. However, there was no difference in body weight, weight gain, and feed intake between ducks fed at the brooding temperature regimen starting at 26, 28, 30, and 32◦ C (P > 0.05, Table 2), which indicated that there existed a temperature plateau and the upper critical temperature for duck growth and the growth response would be reduced when the temperature went beyond the upper critical temperature. Therefore, based on the growth performance at 14 D of age, the upper critical temperature of initial brooding temperature of starter ducks was estimated by brokenline regression. According to this regression, the upper critical temperatures of the initial brooding temperature during the starter period for body weight (Figure 1), weight gain (Figure 2), and feed intake (Figure 3) were 31.3, 31.3, and 31.1◦ C, respectively. Our results
Figure 2. Fitted broken-line plot of 0- to 2-wk weight gain as a function of initial brooding temperature. Broken-line equation is y = 47.5–1.65 × (x –31.3), y = 47.5 when x < 31.3◦ C. 95% CI = 95% confidence interval of the breakpoint.
Figure 3. Fitted broken-line plot of 0- to 2-wk feed intake as a function of initial brooding temperature. Broken-line equation is y = 67.5–2.40 × (x –31.1), y = 67.5 when x < 31.1◦ C. 95% CI = 95% confidence interval of the breakpoint.
showed that the initial brooding temperature should not be above 32◦ C. Recently, a 26.5 to 29.5◦ C ambient temperature was suggested to be the minimum initial ambient temperature for brooding ducklings (FASS, 2010), and it was supported by our results in which the ducks brooded at 32◦ C initially had the growth performance similar to the birds brooded at 26◦ C initially (P > 0.05, Table 2). However, the broiler results were different from ours in ducks. The chicks brooded in the temperature regimen starting at 26.7◦ C had lower body weight and higher feed/gain at 3 wk of age than the birds brooded at higher temperature regimen starting at 35, 32.2, and 29.4◦ C (Deaton et al., 1996).
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Table 3. Effects of brooding temperature on subsequent growth performance of growing Pekin ducks from 2 to 6 wk of age.1 Temperature (◦ C) Week 2
26 28 30 32 34 36 SEM
26 28 30 32 34 36
to to to to to
26 26 26 26 26
Probability Temperature Temperature linear Temperature quadratic 1
Body weight (g/bird) 3055.6b 3165.5a 3173.4a 3235.2a 3207.0a 3012.1b 35.15 0.0008 0.9186 0.0568
Weight gain (g/bird/day)
Feed intake (g/bird/day)
Feed/gain (g/g)
83.5c 86.9a,b,c 87.9a,b 90.7a 90.4a 86.1b,c 1.28
234.0b 247.3a 241.0a,b 250.4a 250.9a 232.2b 3.93
2.80 2.85 2.74 2.76 2.78 2.70 0.032
0.0047 0.2945 0.0419
0.0057 0.8907 0.2257
0.0544 0.1099 0.3251
Results are means with n = 6 per treatment. Means with different superscripts within the same column differ significantly (P < 0.05).
a–c
Table 4. Effects of brooding temperature on subsequent carcass traits of 42-day-old growing Pekin ducks.1 Temperature (◦ C) Week 1
Week 2
Carcass (%)
26 28 30 32 34 36 SEM
26 28 30 32 34 36
67.6 67.8 67.4 67.8 67.2 66.7 0.64
to to to to to
26 26 26 26 26
Probability Temperature Temperature linear Temperature quadratic 1
0.8623 0.0871 0.0844
Breast meat (%)
Leg meat (%)
Abdominal fat (%)
7.31 7.63 8.47 7.70 7.57 7.21 0.480
8.12 7.68 8.14 8.09 8.35 8.46 0.222
1.90 1.87 1.84 1.82 1.80 1.79 0.088
0.5148 0.7415 0.1921
0.2130 0.1009 0.2022
0.9428 0.0003 < 0.0001
Results are means with n = 6 per treatment.
On the other hand, the effects of brooding temperature on subsequent growth performance and carcass traits of ducks during the growing period were shown in Tables 3 and 4. The initial brooding temperature could affect the growth performance of growing ducks (P < 0.05), but it had no effects on carcass traits (P > 0.05). The growing ducks brooded initially at 26 or 36◦ C had lower body weight, weight gain, and feed intake compared to other birds brooded starting from 28 to 34◦ C (P < 0.05). The growth depression of growing ducks brooded at 26 or 36◦ C may be due to the reduction of feed intake and weight gain during the growing period (P < 0.05, Table 3). Our results suggested that too high and low brooding temperature had negative effects on duck performance during the subsequent growing period, although the ducks brooded at 26◦ C had the performance similar to the birds brooded at higher temperature during the starter period. In broilers, the brooding temperature from 26.7 to 35◦ C had no significant effects on the subsequent performance during growing period (Harris et al., 1975; Deaton et al., 1996). However, during the growing period, high mortality took place in broilers brooded at low temperature and some mortality was due to ascites (Deaton et al., 1996). Although our study had
too low mortality in growing ducks, it was cautious that low brooding temperature could lead to ascites. In conclusion, too high and low brooding temperature could have negative effects on the performance of starter and growing Pekin ducks. According to the broken-line regression based on starter growth performance, the upper critical temperature of initial brooding temperature during the starter period was 31.3◦ C and too low initial brooding temperature could lead to growth depression during the subsequent growing period.
ACKNOWLEDGMENTS This work was sponsored by the earmarked fund for National Key Research & Development Program of China (2016YFD0500509) and China Agriculture Research System (CARS-42).
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