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Effects of Air Velocity on Laying Hen Production from 24 to 27 Weeks under Simulated Evaporatively Cooled Conditions
Article in Transactions of the ASABE (American Society of Agricultural and Biological Engineers) · November 2013
DOI: 10.13031/trans.56.10392
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E FFECTS OF A IR V ELOCITY ON L AYING H EN P RODUCTION FROM 24 TO 27 W EEKS UNDER S IMULATED
E VAPORATIVELY C OOLED C ONDITIONS
J. L. Purswell, S. L. Branton, B. D. Luck, J. D. Davis
ABSTRACT. Thermal conditions play a major role in production efficiency in commercial poultry production. Mitigation of thermal stress can improve productivity, but it must be achieved economically. Weather and system design can limit the effectiveness of evaporative cooling, and increased air movement has been shown to improve production efficiency in broilers. The objective of this study was to evaluate the effects of varied levels of air velocity on the productivity of laying hens housed under evaporatively cooled conditions by assessing hen-day egg production (HDEP), feed consumption (FC), feed consumption per dozen eggs (FD), feed conversion ratio (FCR), and egg weight (EW). Three treatments were tested (still air, constant 0.76 m s-1, and constant 1.52 m s-1) at 27.8°C and 82% RH to mimic an evaporatively cooled poultry house in the southeastern U.S. under summer weather conditions. Air velocity test units (wind tunnels) containing cages were constructed; still air treatment groups were housed in identical cage units without the surrounding wind tunnel struc- ture. Four trials were conducted, with two replicate treatment groups per trial, for a total of eight replicate treatment groups in the study. Hens (Hy-Line W-36 variety) were obtained from a commercial laying operation for each trial at 23 weeks of age and housed in an adjacent facility until transfer into the test cages; 48 hens were used in each trial, with eight hens per replicate treatment group, for a total of 192 hens in the study. Feed and water were provided ad libitum, and the lighting program followed primary breeder (Hy-Line) recommendations. Eggs were collected and group weighed for each treatment group for 28 days, and feed consumption was assessed weekly. Results showed that HDEP for the 1.52 m s-1 treatment group improved by 3.8% and 3.3% over still air and 0.76 m s-1, respectively. FC was observed to in- crease with air velocity (p ≤ 0.05). FD increased with increasing air velocity and was significantly greater (p = 0.0043) for both air velocity treatments compared to still air. Other measures of performance including EW and FCR were not different, suggesting that the improvement in HDEP resulted from increased FC. Increased convective cooling increases productivity of laying hens during hot weather by improving thermal comfort when evaporative cooling is limited by weather or system design.
Keywords. Cooling, Egg production, Heat stress, Tunnel ventilation.
hermal comfort is of paramount importance for production efficiency in animal production. Per- formance declines as a result of reduced thermal comfort are well documented in all species and result in significant economic loss (St. Pierre et al., 2003).
Improvements in housing design and environmental control
help to combat thermal stress and mitigate performance decline. Using a temperature-humidity index (THI) model, St. Pierre et al. (2003) estimated a $30 million per year reduction in economic losses resulting from heat stress when the thermal environment was modified to reduce THI.
Heat stress reduces egg production as a result of sup- pressed feed consumption (Smith, 1973) and egg weight as a result of physiological adjustments to heat stress (Smith, 1974). Heat stress conditions significantly suppress body weight and feed consumption when compared to seasonal average conditions or typical summer daily cycles, result- ing in reduced egg production and quality (Mashaly et al., 2004). Webster and Czarick (2000) reported that mean day- time air temperatures in an evaporatively cooled tunnel- ventilated high-rise house in Georgia exceeded 26.7°C in June and 28°C in July, resulting in variable and reduced egg weights. In addition, Mashaly et al. (2004) reported that immune function was inhibited in hens under heat stress conditions.
Evaporative cooling is an economical means to reduce incoming air temperature for layer housing (Gates and Timmons, 1988; Timmons and Gates, 1988) and can im-
Submitted for review in August 2013 as manuscript number SE 10392;
approved for publication by the Structures & Environment Division of ASABE in November 2013. Presented at the 2012 ASABE Annual Meeting as Paper No. 131620737.
Approved for publication as Journal Article No J-12416 of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University.
Mention of company or trade names is for description only and does not imply endorsement by the USDA. The USDA is an equal opportunity provider and employer.
The authors are Joseph L. Purswell, ASABE Member, Agricultural Engineer, and Scott L. Branton, Supervisory Veterinary Medical Officer and Research Leader, USDA-ARS Poultry Research Unit, Mississippi State, Mississippi; Brian D. Luck, ASABE Member, Graduate Research Assistant, and Jeremiah D. Davis, ASABE Member, Associate Professor, Department of Agricultural and Biological Engineering, Mississippi State University, Mississippi State, Mississippi. Corresponding author: Joseph Purswell, P.O. Box 5367, Mississippi State, MS 39762; phone: 662-320- 7480; e-mail: [email protected].
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prove egg production (Ugurlu and Kara, 2003) and livabil- ity (Garner et al., 2012). Cooling through direct evapora- tion from the body surface of the bird has been shown to limit body temperature rise during thermal challenge, and the cooling effect increased with increasing air velocity (Yanagi et al., 2002; Tao and Xin, 2003). Surface cooling through direct water sprinkling on laying hens resulted in increased egg production overall (2.6%) and for the top tier (5.6%) in a layer house in Iowa (Ikeguchi and Xin, 2001).
The principles of convective cooling have been applied to poultry from both a classical heat transfer perspective (Wathes and Clark, 1981; Mitchell, 1985) and a biological perspective (Tzschentke and Nichelmann, 1986; Simmons et al., 1997). Tzschentke and Nichelmann (1986) illustrated the wind-chill effect with laying hens, reporting that the upper critical temperature was elevated from 25°C to 35°C as air velocity increased from 0.2 to 1.2 m s-1. Tunnel venti- lation is often used to enhance heat loss through convec- tion, and many poultry production facilities typically em- ploy some form of tunnel ventilation during warm weather.
Production efficiency in broiler chickens is significantly improved as ventilation rates exceed that required to limit temperature rise and result in increased air velocity through the facility. Ventilation systems in commercial broiler houses are sized to provide air velocities in excess of 2.5 m s-1 for new construction and can range as high as 4 m s-1 (J. Donald, personal communication, 24 June 2013). While the effects of increased air velocities for broiler production are well documented in the literature (Lott et al., 1998;
Simmons et al., 2003; Dozier, 2005a, 2005b; Dozier et al., 2006), the effects of air velocity on egg production have not been addressed.
Clearly, thermal stress can impact production efficiency in laying hens, and improving thermal comfort results in improved productivity. The vast majority of layer houses in the southeastern U.S. are evaporatively cooled (S. Miller, Cal-Maine Foods, personal communication, 25 October 2013) while most layer houses in the Midwestern U.S. are not equipped with evaporative cooling systems (H. Xin, Egg Industry Center, personal communication, 25 October 2013). Cooling via evaporation is limited by ambient weather conditions and system efficiencies; thus, the re- maining avenue to increase convection heat transfer is through increased air velocity, and this approach has been used with great success in broiler production. Modern tun- nel-ventilated layer houses also rely on convective cooling, and the variations in air velocity at bird level may produce
differing levels of thermal comfort. However, information regarding the effects of differing air velocity at bird level on layer chickens under evaporatively cooled conditions is limited in the literature. The objective of this study was to evaluate the effect of varied levels of air velocity on egg production rate, feed usage, and feed efficiency for laying hens under simulated evaporatively cooled conditions dur- ing warm weather.
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ATERIALS ANDM
ETHODSA total of four trials was conducted using hens (W-36 variety, Hy-Line International, West Des Moines, Iowa) obtained from a commercial laying operation at 23 weeks of age for each trial; 48 hens were used in each trial, for a total of 192 hens in the study. All trials were conducted in an environmentally controlled room with conditions set at 27.7°C and 82% RH to mimic warm weather conditions in the southeastern U.S. in evaporatively cooled facilities. All procedures were approved by the USDA-ARS Animal Care and Use Committee at the Mississippi State location.
The hens were housed in an adjacent facility for one week prior to commencement of the study period at 24 weeks of age, when they were transferred into one of four wind tunnels or one of two control (still air) pen units.
Schematics of the wind tunnel and the experimental room layout are shown in figures 1 and 2, respectively. Cage units with ten individual bird cages were used for both the tunnel and still air treatments (fig. 3); individual bird cages measured 45.7 L × 30.5 W × 30.5 H cm (18 × 12 × 12 in.), resulting in a cage area of 1394 cm2 (216 in.2) for each hen.
Treatment groups consisted of eight hens, and the end cag- es near the inlet and the fan were left empty during the study period.
The wind tunnels were constructed with lumber frames and plywood sheathing. The tunnel units measured 337.8 L
× 78.7 W × 71.1 H cm (133 × 31 × 28 in.). The tops of the tunnel units were constructed of optically clear acrylic sheeting and sealed against air leakage with weather strip- ping. Two doors were placed in the sidewall to manage feeding and bird care (upper) and egg collection (lower).
Each tunnel was equipped with a 61 cm direct-drive fan (AT24G3, Munters Aerotech, Mason, Mich.) with a 249 W three-phase electric motor. Air velocity was controlled by changing the fan motor speed with a variable frequency drive (GS2-1P0, Automation Direct, Cumming, Ga.). Air
Figure 1. Wind tunnel plan view. Hens were placed in the center eight cages (2 through 9); cage areas in red were left empty during the study period. The shaded area represents the feed trough, and the dashed line represents the nipple drinker line. Air velocity was measured in each tunnel unit prior to the start of each trial in cage 6 (). Air movement is from right to left.
velocity was adjusted without hens in the tunnel enclosure using a rotating vane anemometer (8322, TSI, Inc., Shore- view, Minn.) suspended in the center cage (cage 6, fig. 1) prior to the start of each trial.
The cage units were equipped with a continuous trough feeder and nipple drinker lines. Feed and water were avail- able ad libitum. The diet was corn and soy based and was formulated to meet or exceed National Research Council requirements for laying hens (NRC, 1994). The diet con- tained 2791 kcal kg-1 metabolizable energy and 16.1%
crude protein. Lighting was provided with incandescent bulbs, and the lighting schedule was adjusted according to primary breeder recommendations (Hy-Line, 2013).
Feed consumption (FC) was measured weekly. Eggs were collected and group weighed daily. Manure was re- moved from the tunnels weekly. Body weight (BW) data were collected as hens were placed into the cage units at 24 weeks of age and removed at 27 weeks of age.
STATISTICAL DESIGN AND ANALYSIS
Three treatments were tested in each trial: 1.52 m s-1 (300 ft min-1), 0.76 m s-1 (150 ft min-1), and still air (<0.25 m s-1, 50 ft min-1). The treatment air speeds were chosen based on spot measurements within cages in a tun- nel-ventilated high rise layer house at a commercial egg farm near the tunnel inlet, exhaust fan outlet, and halfway
Figure 2. Experimental room layout. Arrows indicate direction of airflow. Hatched areas show locations of air outlets, and heavy vertical lines indicate partitions to separate still air cage units from air movement induced by wind tunnels.
Figure 3. Cage units for air velocity treatments (top) and still air treatment (bottom). The upper door on the wind tunnel is open to show the arrangement of cages inside the tunnel.
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between. Each treatment was represented by two replicates in each trial; treatment assignments for each cage unit are shown in table 1. Weekly mean hen-day egg production (HDEP), FC, egg weight (EW), feed consumption per doz- en eggs (FD), and feed conversion ratio (FCR) were ana- lyzed for differences using a mixed model (PROC MIXED) with repeated measures (week as the repeated measures parameter) in SAS (ver. 9.2, SAS Institute, Inc., Cary, N.C.). Hen-day egg production (HDEP) data were subject- ed to arcsine transformation to normalize the distribution.
Sokal and Rohlf (1995) recommend transforming propor- tion data when it falls outside the range of 30% to 70%;
HDEP data exceeded or approached 70% for each weekly measurement period. Differences in least square means were separated using Fisher’s LSD (Ott and Longnecker, 2009) implemented within SAS (Saxton, 1998); signifi- cance was assessed at p ≤ 0.05.
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ESULTS ANDD
ISCUSSIONPerformance results from four trials are shown in ta- ble 2. Final BW was decreased when compared to initial BW for the still air and 1.52 m s-1 treatments. Final BW values were not different among the air velocity treatments, while the BW in the still air treatment was reduced signifi- cantly (p = 0.0166). Average daily FC was significantly different among all treatments (p < 0.0001) and increased with increasing air velocity. FD increased with increasing air velocity and was significantly greater (p = 0.0043) for both air velocity treatments compared to still air. FCR was not different among the treatments, and mean HDEP in- creased significantly (p = 0.0160) for the 1.52 m s-1 treat- ment over the other two treatments (still air and 0.76 m s-1).
Weekly HDEP and feed consumption data are shown in figures 4 and 5, respectively. HDEP increased through week 26 and decreased at week 27 for all treatments; the still air treatment showed a greater decrease at week 27 when compared to the air velocity treatments. The layer variety used in this study (Hy-line W-36) reaches peak lay
Figure 5. Weekly feed consumption (FC) from 24 to 27 weeks. Values are means and standard errors (n = 8).
at 26 weeks of age (Hy-line, 2012); HDEP at peak lay for
“average” conditions is 95% and starts to decline at 31 weeks of age. While the still air treatment showed the largest decrease in HDEP, it is the only treatment that dropped below nominal HDEP for “average” conditions.
The air velocity treatments approached or exceeded 95%
HDEP, with 97.5% and 94.5% HDEP for the 1.52 and 0.76 m s-1 treatments, respectively. FC increased through- out the study period for all treatments, and the rate of in- crease was concurrent with increasing air velocity.
Figure 4. Weekly mean hen-day egg production (HDEP) from 24 to 27 weeks. Values are means and standard errors (n = 8).
Table 1. Treatments applied to cage units in each of four trials. Each trial had two replicates of each treatment, for a total of eight replicates per treatment for the study.
Trial
Air Speed (m s-1) Tunnel
1
Tunnel 2
Tunnel 3
Tunnel 4
Still Cage 1
Still Cage 2 1 1.52 0.76 1.52 0.76 <0.25 <0.25 2 0.76 1.52 0.76 1.52 <0.25 <0.25 3 1.52 0.76 1.52 0.76 <0.25 <0.25 4 0.76 1.52 0.76 1.52 <0.25 <0.25
Table 2. Effect of differing air velocity on production characteristics of laying hens. Table values represent least square means (n = 8) and were separated using Fisher’s LSD. Within a column, means followed by different letters are significantly different (p ≤ 0.05).[a]
Air Velocity (m s-1)
Initial BW (g hen-1)
Final BW (g hen-1)
FC (g d-1 hen-1)
FD (g dozen-1)
FCR (kg feed:kg egg)
EW (g)
HDEP (%) Still air 1357 1322 b 84.0 c 1108 b 1.79 51.6 92.3 b
0.76 1362 1369 a 88.9 b 1170 a 1.87 52.1 92.8 b
1.52 1360 1354 a 93.2 a 1174 a 1.87 52.6 96.1 a
Pooled SEM 19.9 23.4 3.8 42.4 0.06 0.6 0.06
p-value 0.9591 0.0166 <0.0001 0.0043 0.1650 0.2938 0.0160
[a] BW = body weight, FC = feed consumption, FD = feed consumption per dozen eggs, FCR = feed conversion ratio, EW = egg weight, and HDEP = hen-day egg production.
The expected performance for W-36 hens between 24 and 27 weeks of age is shown in table 3 (Hy-Line, 2012).
Initial and final BW was lower for all trials when compared to the performance reference. Growth trajectory often var- ies from expected values in commercial production to man- age production performance or as a result of aberrant weather conditions (J. Self, Cal-Maine Foods, personal communication, 26 June 2013). The expected FC falls within the range of FC observed in this study, as does FCR.
EW is lower than expected and likely resulted from re- duced thermal comfort. Smith (1974) concluded that at air temperatures above 26°C, reduced egg weights resulted from the physiological effects of heat stress, rather than reduced FC. The HDEP for the highest air velocity treat- ment (1.52 m s-1) exceeded the expected HDEP for “opti- mum” conditions, while the other two treatments fall below those expected for “average” conditions. The increased FC and associated improvements in HDEP with increasing air velocity revealed in this study mirror the improved FC and live performance observed in broilers (Dozier et al., 2005a, 2005b; Dozier et al., 2006).
S
UMMARYWind tunnels were constructed to assess the effects of in- creased convective cooling through increased air velocity on egg production. The impact of three different air velocities (still air, 0.76 m s-1, and 1.52 m s-1) was evaluated at a com- mon air temperature and RH condition of 27.8°C and 82%
during three trials. The air velocity of 1.52 m s-1 improved HDEP by 3.8% and 3.3% over still air and 0.76 m s-1, respec- tively. Increases in HDEP were concurrent with significant increases in FC, which was significantly different among the treatments. FD increased with increasing air velocity and was significantly greater for both air velocity treatments compared to still air. Other measures of performance, includ- ing EW and FCR, were not significantly different, suggesting that the improvement in HDEP resulted from increased FC.
Efforts to design layer housing to achieve increased convec- tive cooling at bird level will likely prove beneficial to max- imize hen thermal comfort and production efficiency by maintaining nominal FC during hot weather. Future work should include assessment of egg quality attributes as a result of increased convective cooling.
ACKNOWLEDGEMENTS
The authors would like to recognize William Elliot, Ja- son Johnson, and John Prisock at the USDA-ARS Poultry Research unit for their efforts in study management and data collection. We gratefully acknowledge Dr. Elizabeth Kim (USDA-ARS) and Dr. Hongwei Xin (Iowa State Uni- versity) for their critical reviews of the manuscript.
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EFERENCESDozier III, W. A., B. D. Lott, and S. L. Branton. 2005a. Growth responses of male broilers subjected to increasing air velocities at high ambient temperatures and a high dew point. Poultry Sci.
84(6):962-966.
Dozier III, W. A., B. D. Lott, and S. L. 2005b. Live performance of male broilers subjected to constant or increasing air velocities at moderate temperatures with a high dew point. Poultry Sci. 84(8):
1328-1331.
Dozier III, W. A., J. L. Purswell, and S. L. Branton. 2006. Growth responses of male broilers subjected to high air velocity for either twelve or twenty-four hours from thirty-seven to fifty-one days of age. J. Appl. Poultry Res. 15(3): 362-366.
Garner, J. P., A. S. Kiess, J. A. Mench, R. C. Newberry, and P. Y.
Hester. 2012. The effect of cage and house design on egg production and egg weight of White Leghorn hens: An epidemiological study. Poultry Sci. 91(7): 1522-1535.
Gates, R. S., and M. B. Timmons. 1988. Stochastic and
deterministic analysis of evaporative cooling benefits for laying hens. Trans. ASAE 31(3): 904-909.
Hy-Line. 2012. Hy-Line W-36 Performance Standards Manual. 3rd ed. West Des Moines, Iowa: Hy-Line International.
Hy-Line. 2013. Basic rules for lighting programs. West Des Moines, Iowa: Hy-Line International. Available at: www.hylinena.com/
redbook/Lighting_program/Lighting_rules.html. Accessed 26 June 2013.
Ikeguchi, A., and H. Xin. 2001. Field evaluation of a sprinkling system for cooling commercial laying hens in Iowa. Applied Eng. in Agric. 17(2): 217-221.
Lott, B. D., J. D. Simmons, and J. D. May. 1998. Air velocity and high temperature effects on broiler performance. Poultry Sci.
77(3): 391-393.
Mashaly, M. M., G. L. Hendricks III, M. A. Kalama, A. E. Gehad, A. O. Abbas, and P. H. Patterson. 2004. Effect of heat stress on production parameters and immune responses of commercial laying hens. Poultry Sci. 83(6): 889-884.
Mitchell, M. A. 1985. Effects of air velocity on convective and radiant heat transfer from domestic fowls at environmental temperatures of 20 and 20 C. British Poultry Sci. 26(3): 413- 423.
NRC. 1994. Nutrient Requirements of Poultry. 9th ed. Washington, D.C.: National Research Council.
Ott, R. L., and M. T. Longnecker. 2009. An Introduction to Statistical Methods and Data Analysis. Belmont, Cal.: Duxbury.
Saxton, A. M. 1998. A macro for converting mean separation output to letter groupings in Proc Mixed. In Proc. 23rd SAS Users Group Intl. Meeting, 1243-1246. Cary, N.C.: SAS Institute, Inc.
Simmons, J. D., B. D. Lott, and J. D. May. 1997. Heat loss from broiler chickens subjected to various air speeds and ambient temperatures. Applied Eng. in Agric. 13(5): 665-669.
Simmons, J. D., B. D. Lott, and D. M. Miles. 2003. The effects of high air velocity on broiler performance. Poultry Sci. 82(2): 232- 234.
Smith, A. J. 1973. Some effects of high environmental temperatures on the productivity of laying hens (A review). Trop. Animal Health and Prod. 5(4): 259-271.
Table 3. Expected performance for Hy-Line W-36 hens from 24 to 27 weeks of age (adapted from Hy-Line, 2012). Data represent averages of expected performance parameters over the four week period tested in this study.
Parameter Mean Value
BW (g hen-1) 1495
FC (g d-1 hen-1) 88.5
EW (g) 56.4
HDEPOptimum (%)[a] 95.25
HDEPAverage (%)[a] 94.25
FCR (kg feed:kg egg)[b] 1.80
Cumulative mortality (%) 0.55
[a] “Optimum” and “Average” refer to production conditions and are not explicitly defined.
[b] Feed conversion rate is listed for 18 to 80 weeks of age.
1508 TRANSACTIONS OF THE ASABE Smith, A. J. 1974. Changes in the average weight and shell
thickness of eggs produced by hens exposed to high
environmental temperature: A review. Trop. Animal Health and Prod. 6(4): 237-244.
Sokal, R. R., and F. J. Rohlf. 1995. Chapter 13: Assumptions of analysis of variance. In Biometry: The Principles and Practice of Statistics in Biological Research. 3rd ed. New York, N.Y.: W.H.
Freeman.
St. Pierre, N. R., B. Cobanov, and G. Schnitkey. 2003. Economic losses from heat stress by U.S. livestock industries. J. Dairy Sci.
86(supp.): E52-E77.
Tao, X., and H. Xin. 2003. Surface wetting and its optimization to cool broiler chickens. Trans. ASAE 46(2): 483-490.
Timmons, M. B., and R. S. Gates. 1988. Predictive model of laying hen performance to air temperature and evaporative cooling.
Trans. ASAE 31(5): 1503-1509
Tzschentke, B., and M. Nichelmann. 1986. The influence of wind speed on heat production in laying hybrids (Gallus domesticus) of different ages at various relative humidities. J.
Thermal Biol. 11(2): 109-113.
Ugurlu, N., and M. Kara. 2003. The effects of evaporative cooling on reduction of cage house temperature and production performance of the laying hens. Archiv für Geflügelkunde 67(3):
138-142.
Wathes, C. M., and J. A. Clark. 1981. Sensible heat transfer from the fowl: Radiative and convective heat losses from a flock of broiler chickens. British Poultry Sci. 22(2): 185-196.
Webster, A. B., and M. Czarick. 2000. Temperatures and performance in a tunnel-ventilated, high-rise layer house. J.
Appl. Poultry Res. 9(1): 118-129.
Yanagi, T., H. Xin, and R. S. Gates. 2002. Optimization of partial surface wetting to cool caged laying hens. Trans. ASAE 45(4):
1091-1100.
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