1、4719 (RP-1044) Heat and Moisture Production of Poultry and Their Housing Systems: Molting Hens H. Justin Chepete, Ph.D. ABSTRACT Heat and moisture production rates (HE MP) of modern 68- to 75-week-old Hy-Line W-36 laying hens during molting were measured using large-scale indirect calorimeters that
2、mimic commercial production settings. The measurements were performed continuously during acclimation, fasting, restricted feeding, and post-molt. Total HP (THP) was parti- tioned into latent and sensible HP (LHE SHP) that incorpo- rated influence of fecal moisture evaporation. THP during fasting (a
3、veraging 4.8 Wkg) andrestrictedfeeding (averaging 6. O W/kg) averaged 29% and 13% lower than that duringpost- molt (averaging 6.8 W/kg). Correspondingly, LHP averaged 1.9 W/kg and 1.8 W/kg and was 31% and 34%, respectively, lower than that (averaging 2.7 W/kg) during post-molt. Like- wise, SHP avera
4、ged 2.9 W/kg during fasting and was 28% lower than during post-molt (averaging 4.1 Wlkg). The aver- age SHP under restricted feeding and post-molt was similar (4.2 vs. 4.1 Wkg, respectively). Respiratory quotient (Re) averaged O. 71, O. 76, and 0.92 during fasting, restricted feed- ing, and post-mol
5、t, respectively. Heat production rates during the lightperiod were signijcantly higher Cp 0.05) than those during the dark period. Daily mean and diurnal LHP as percentages of THP were similar during fasting andpost-molt but they were IO% lower during restricted feeding. The results of this study pr
6、ovide a new thermal load database for design of housing ventilation systems for laying hens undergoing molting phase. INTRODUCTION Molting is a natural process of all birds in an endeavor to renew their feathers (Lucas and Stettenheim 1972; North 1984) prior to migration, shorter days, or cooler wea
7、ther Hongwei Xin, Ph.D. Member ASHRAE (North, 1984) and is regulated by hormones (Van der Meulen 1939; Blivaiss 1947; Perek et al. 1957; Whittow 1976). Normally, wild chickens molt once a year, and the molting is not associated with the laying cycle (North 1984). Domestic chickens are bred for high
8、egg production and go into molting after a long and intensive laying period. In order to give them rest, molting is often induced, particularly at or near the time when the birds naturally molt (Van der Meulen 1939; Sturkie 1954). This is achieved through several means, such as feed withdrawal (Nole
9、s 1966; North 1984; Witham 2001), drugs and chemicals (Van der Meulen 1939; Sturkie 1954; Adams 1955; Whitehead and Shannon 1974; Scott and Creger 1976; North 1984), and light reduction (North 1984). The methods that are widely adopted are those that create the least amount of stress, produce a rapi
10、d molt, and get birds back to egg production quickly. The thyrotrophic and thyroid hormones have been reported to promote molting (Van der Meulen 1939; Blivaiss 1947; Whittow 1976), impair egg laying (Zawadowsky and Nesmeyanova 1937), and increase metabolic activity (Whit- tow 1976). Loss of feather
11、s, naturally or artificially, causes an increase in heat production and heat loss (Perek and Sulman 1945; Hoffman and Shaffner 1950). Economic circumstances, such as anticipation of high egg prices or lack of available cash due to depressed egg prices, often drive decisions to put hens into a molt (
12、North 1984; Bell and Swanson 1974). The merits of molting laying hens include increased egg production (up to 85% to 90% of the first year production), larger egg size, and improved eggshell quality (North 1984; Witham 2001). However, these levels would be somewhat lower than their best pre-molt val
13、ues (Hy-Line 2000-200 1). H. Justin Chepete is a former graduate research assistant and Hongwei Xin is a professor in the Agricultural and Biosystems Engineering Department, Iowa State University, Ames, Iowa. 274 02004 ASHRAE. In view of the above-mentioned physiological implica- tions on molting or
14、 molted birds, there is need to provide them with an optimum environment through adequate ventilation. Building ventilation rate designs are based on the heat and moisture production rates (HP and MP) of the housed animals. Data on HP and MP of non-molting laying hens have recently been collected (C
15、hepete et al. 2004), and that of molting hens was not found in the literature search (Chepete and Xin 2002). This suggests that ventilation rates for molting hens are designed presumably using data of non-molting ones. In order to provide molting hens with optimum ventilation rates, specific HP and
16、MP data for this situation are needed. There- fore, the objective of this study was to measure HP and MP of W-36 hens during molting conditions that follow current commercial production practices as part of the effort to systematically update HP and MP data for design and opera- tion of modern poult
17、ry housing systems. MATERIALS AND METHODS Experimental Birds and Facility A large-scale indirect calorimeter system, consisting of four calorimeter chambers (1.5 W x 1.8 DI x 2.4 HI m) (Xin and Harmon 1996; Xin et al. 1998) was used for this study. The gas (O2 and CO,) analyzers were calibrated twic
18、e daily throughout the seven-week measurement period to ensure the system measurement uncertainty of *OS W per chamber (65-W HP output). In all trials performed, metal pans were placed under the cages to collect feces, and, thus, MP included contribution from both birds and fecal matter. The latent
19、and sensible heat production rates (LHP or SHP) measured were, thus, room values. Commercial management practices (feeding, photoperiod, temperature, stocking density, and manure handling) were followed throughout the trial, as described below. Specifically, manure was removed from all chambers twic
20、e weekly. Birds were group-weighed weekly throughout the trial. Measurements of HP and MP A flock of 252 hens at 68 weeks of age and averaging 1.7 kg was procured from a local commercial farm and delivered to the measurement laboratory. Upon arrival, the birds were group-weighed and randomly allocat
21、ed to the four indirect calorimeter chambers with 63 birds per chamber, 7 hens per cage. These bird numbers ensured sufficient changes in air composition (O, and CO2) for the instruments to make accu- rate measurements. Each chamber had a movable supporting stand with nine cages (55 LI x 50 W x 41 H
22、I cm each). The birds were acclimated for a week. During this period, birds were fed ad libitum (Table 1). The lighting schedule was 16hL:8hD, and the initial temperature setpoint was 26.7“C, which was then reduced by 1 OC daily until it reached 20C. At the beginning of the second week, feed was wit
23、hdrawn, temperature was kept at 20C, and lighting schedule changed to 9hL: 15hD. The objective of feed withdrawal was to induce Table 1. Dietary Ingredients (% Unless Otherwise Noted) of Feed Used in the Study Layer Pullet Layer Ration* Rationt Rationt Dietary Content ME (MJkg) Crude protein Crude f
24、at Crude fiber Calcium Total phosphorus Available phosphorus Sodium Lysine Methionine Methionine and Cystine Tryptophan Threonine Protein equivalent 11.86 14.00 2.90 2.40 3.85 0.50 0.50 0.18 0.73 0.33 0.60 NIA NIA NIA 12.54 16.81 NIA NIA 0.94 NIA 0.37 0.15 0.89 0.39 0.68 0.20 0.63 18.96 11.95 16.00
25、4.50 2.40 4.25 0.64 0.45 0.19 0.85 0.40 0.69 NIA NIA NIA * acclimation period 1 post-molt period N/A = information not available reshicted feeding period molting and reduce bird body mass (M) to an equivalent of a 20-week-old pullet of the same breed (1.22 to 1.27 kghird). The birds were expected to
26、 stop laying eggs at this Mrange. To monitor bird M, a group of 18 birds was randomly sampled and weighed from each calorimeter every two days. When the target Mrange was reached, birds were put on restricted feed- ing with pullet ration (Table 1) for two weeks at an average of 5.2 kg/( 100-day) to
27、provide maintenance energy while main- taining theirMstrictly between 1.22 to 1.27 kg. IfMincreased beyond the range, addition of feed was skipped for a day. After the restricted feeding period, room temperature was raised to 24.4“C, lighting increased to 13hL: 1 lhD, and birds were fed layer ration
28、 (Table 1) ad libitum for three weeks during which they were expected to increase M and resume laying. Through- out the experimental period, the birds had free access to water through nipple drinkers. Relative humidity (RH) ranged from 37% to 45%. Light intensity was maintained at 5 to 1 1 lux. The
29、experimental protocols complied with the guidelines on the care and use of animals for research by the institutional committee. Data Analysis and Presentation For each 24-h period of the trial, the data were separated into dark and light periods, and their time-weighted averages (TWA) computed. The
30、data were subjected to analysis of vari- ance using Statistical Analysis Software (SAS) (SAS Institute Inc. 1999-2000). The measured parameters were presented ASHRAE Transactions: Research 275 graphically as functions of bird age and in a summary table of their mean values. Data collected during cle
31、aning of the calo- rimeters and weighing of the birds were excluded from anal- ysis. RESULTS AND DISCUSSION Figure 1 shows the changes in plumage of the hens during fasting through post-molt period. Egg production and bird M are both depicted in Figures 2 through 4. Total heat production (THP), LHP,
32、 SHP, and respiratory quotient (RQ, C02/02) at the room level (LHP and SHP) under light, dark, and TWA conditions are summarized in Table 2 as two- to four-day aver- ages. The HP parameters are shown in Figures 2 through 4, while RQ is shown in Figure 5. LHP as a percentage of THP is shown in Figure
33、 6. Egg Production During the acclimation period, egg production averaged 39 g/(bird-day). Upon fasting, egg production dropped dras- tically and ceased by the end of the fasting period. This is consistent with reports by Witham (2001) and Zawadowsky and Nesmeyanova (1 937). Most of the eggs laid tw
34、o days after onset of fasting broke into the metal pans, presumably due to thin eggshells as the birds lacked calcium. No eggs were produced during restricted feeding period. Egg production resumed about 1 1 days after start of the post-molt period when birds were fed ad libitum. Bird Mass Upon arri
35、val, the birds averaged 1.7 kg in M that was reduced to an average of 1.2 kghird when fasting. During restricted feeding, M varied from 1.2 to 1.3 kg/bird-within the industry-recommended range for birds not to lay eggs. During post-molt, Mincreased to a range of 1.4 to 1.5 kghird. Figure 1 (a) Layin
36、g hens during the fasting period, (b) loss of feathers during the restrictedfeeding period, and (c) feathers rejuvenating during the post-molt period. 276 ASHRAE Transactions: Research 10 9 8 s7 s P 6 S m s5 54 I s e3 2 1 O 1 I I Pcdimtiul I FasEing I Wsbidedfeedlng I Rabndt(ablibfeedng) I I (MK) :
37、Wib) I I . I I iw I P i . I . I . 1 f(“ . - 1 A- r; 4 I I I I . I . I I . i 7-k I i i I ti I . I . 1 i 60 54 48 A , 42 9 360 a 305 z 24s e n e 18 12 6 O w 68 69 70 71 72 73 74 75 Bitd age (week) Figure 2 Total heatproduction rate (THP), body mass (M), and egg production (EP) of molting W-36 laying h
38、ens as functions of bird age. TWA = time-weighted average. 68 69 70 71 72 73 74 75 Bird age (week) Figure 3 Latent heat production rate (LHP), body mass (M), and egg production (EP) of molting W-36 laying hens as functions of bird age. TWA = time-weighted average. ASHRAE Transactions: Research 277 6
39、8 69 70 71 72 73 74 75 Bird age (week) Figure 4 Sensible heat production rate (SHP), body mass (M), and egg production (EP) of molting W-36 laying hens as functions of bird age. TWA = time-weighted average. Behavioral and Physical Observations Birds were observed to peck on different objects, a feed
40、- seeking activity when fasting, as reported by Lundy et al. (1 978). During restricted feeding, the birds scrambled at feed and ate vigorously and competitively the entire time. Scram- bling for feed was also observed during the first day of post- molt and thereafter stopped as birds continued to h
41、ave access to ad-lib feeding. During fasting, the birds had fairly good feather cover (Figure la). They then shed large amount of feathers during the first week of restricted feeding (Figure lb), and this was consistent with reports by Lucas and Stettenheim (1 972) and North (1 984). The feathers re
42、juvenated during post-molt (Figure lc). Total Heat Production (THP) Relationship between THP and bird age is shown in Figure 2. There were significant differences (Pi tu -I ASHRAE Transactions: Research 279 12 I .I 1.0 0.9 0.3 O2 0.1 Ox) . k. 60 .-.T.* -. TI .v -“r“.“.“,“ ?._I -.T.-v.“.Trr-7-,* “, _
43、._ I-.- ll-F.F.*I - -.-. ll-Tm _. _ 1: (ad-lib) I I 1 Affilimation I Fasting I Wstrided feeding Postmolt (ad-lib feeding) I (13hL) o .- Y a . $ I i 1 .mg Hohan and Shafner 1950). Other contributing factors may include increased bird activities such as vigorous feeding (Yunianto et al. 1997) and chan
44、ges in posture (Lundy et al. 1978). Up to 25% of the increase in THP is related to physical activity in laying hens (Boshouwers and Nicaise 1985). Standing alone was reported to increase HP of Light Sussex cocks by 40% to 50% (Deigh- ton and Hutchinson 1940). The oscillations in the THP profile were
45、 caused by periodic skipping of feeding to keep birds M within the recommended range. During the latter ten days of this period, average THP stabilized within a range of 5.4 to 5.9 Wkg and was 13% lower and 5% to 23% higher than that during acclimation and fasting, respectively. Energy restric- tion
46、 decreases metabolic rate, since the latter increases with increase in metabolizable energy (Mitchell 1962). During post-molt, average THP increased slightly and stabilized at 6.7 to 6.9 Wkg. Besides activity, heat increment of feeding and the cost of egg synthesis and oviposition (van Kampen 1976)
47、are likely to be responsible for the nature ofthe THP trend during this period. Under similar conditions, Chep- ete et al. (2004) reported a value of 6.7 Wkg for 1.53 kg (64- week-old) laying hens. THP during post-molt was 23% to 52% higher than that during fasting. Meltzer (1987) noted a 25% to 68%
48、 higher THP in fed than starved adult birds. Lundy et al. (1 978) reported a 27% or 29% lower THP in starved than in fed Babcock or Warren birds, respectively, at 19C to 2 1 “C ambi- ent temperature. A THP range of 6.6 to 6.8 Wkg for a 1.8 kg leghorn laying hen (Albright 1990) has been widely used i
49、n ventilation design for laying hens. The values are 2 1% to 50% and 5% to 22% higher than that measured in this study during fasting and restricted feeding periods, respectively. For molting birds, use of the higher HP values may result in overventilation during fasting and restricted feeding periods, which may adversely affect production efficiency. Latent Heat Production (LHP) Figure 3 shows LHP as a function ofbird age. There were significant differences (P 0.05) in LHP among acclimation, fasting, restricted feeding, and post-molt for both light and dark
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