- Email: [email protected]
Reproductive Performance of Broiler Breeders Exposed to Cycling High Temperatures from 17 to 20 Weeks of Age1
EDUCATION AND PRODUCTION Reproductive Performance of Broiler Breeders Exposed to Cycling High Temperatures from 17 to 20 Weeks of Age1 J. A. RENDEN and G. R. McDANIEL Alabama Agricultural Experiment Station, Department of Poultry Science, Auburn University, Alabama 36849 (Received for publication September 23, 1983) ABSTRACT Forty male and 240 female broiler breeders were placed in cages within environmental chambers (20 males or 40 females per chamber) at 14 weeks of age. Chamber temperatures were maintained at 21.3 ± 2.5 C, and relative humidity (RH) ranged from 40 to 50%. Ventilation rate was approximately 47.2 liters/sec per chamber, and light was provided from 0600 to 1800 hr. Feed was restricted daily according to industry recommendations, and water was provided ad libitum. From 17 to 20 weeks of age, control (C) chambers were kept at constant 21.0 ± 1.4 C with 45 ± 5% RH, and heat-treated (HT) chambers were cycled from 24.4 ± 5.5 C (45 ± 5% RH) during 1800 to 0800 hr to 36.0 ± 2.8 C (15 ± 5% RH) during 0800 to 1800 hr. Body weights were recorded at biweekly intervals. At 18 and 20 weeks of age, blood samples and rectal body temperatures were obtained randomly from five fasted birds per chamber at 0800 and 1400 hr. From 20 to 60 weeks of age, all birds were kept in individual cages in a conventional fan-ventilated house. Maximum temperature never exceeded 30 C, and average RH was 65.0%. Reproductive parameters were monitored and body weights were obtained at 4-week intervals. There were no significant treatment effects for body weight, body temperature, or differential leukocyte counts. Hematocrits were significantly lower for HT females than controls, and heat treatment did not result in consistent changes in plasma glucose or total proteins. There were no significant differences between C and HT birds for age of sexual maturity, egg production, egg weight and specific gravity, fertility, or semen production except that sperm concentration and percent abnormal sperm were greater in HT males than controls from 28 to 31 weeks of age. Evidently, the conditions of heat treatment used in this study (i.e., cycling high temperature with low RH) were not stressful and did not cause detrimental changes in the subsequent performance of broiler breeders. (Key words: broiler breeders, temperature, reproduction) 1984 Poultry Science 63:1481-1488 INTRODUCTION It is a complaint by t h e breeder industry t h a t spring-hatched birds grown during t h e h o t s u m m e r m o n t h s seldom perform as well as birds grown at o t h e r times of t h e year. It has been suggested t h a t reduced reproductive performance is caused b y exposure of breeders to high t e m p e r a t u r e s prior t o sexual m a t u r i t y . Draper and Lake ( 1 9 6 7 ) speculated t h a t inappropriate t r e a t m e n t during t h e growing period m a y have repercussions in t h e adult bird. H u s t o n et al. ( 1 9 5 7 ) maintained various breeds of hens from hatching to 6 m o n t h s of age at either constant 32.2 C or n o r m a l b r o o d ing and a m b i e n t t e m p e r a t u r e s (5.9 C to 16.9 C). Percent hen-day egg p r o d u c t i o n was unaffected b y t e m p e r a t u r e in Single C o m b White Leghorn (SCWL) hens, b u t it was decreased in
1 Alabama Agricultural Experiment Station Journal Series No. 12-83507.
New Hampshires (NH) and White P l y m o u t h R o c k s (WPR) maintained at high t e m p e r a t u r e . Egg weight, b o d y weight, and feed c o n s u m p tion were decreased for all three breeds at 32.2 C. H u s t o n and Carmon ( 1 9 5 8 ) m a i n t a i n e d SCWL hens and SCWL, NH and WPR males from hatching through the first laying year at either 32.2 C or a m b i e n t t e m p e r a t u r e . Fertility of hens k e p t at ambient t e m p e r a t u r e was significantly greater t h a n fertility of t h e heat treated hens. There were n o significant differences among male t r e a t m e n t g r o u p s for fertility, although there were significant breed differences. Matings b e t w e e n birds k e p t in similar environments had higher fertility t h a n matings between birds in different environm e n t s . T h e r e were no differences in h a t c h ability a m o n g any of t h e mating g r o u p s . V o et al. ( 1 9 8 0 ) maintained male and female SCWL chickens at one of t h r e e c o n s t a n t temperatures ( 2 1 , 2 9 , or 35 C) from 2 t o 33 weeks
1481
1482
RENDEN AND McDANIEL
of age. Sexual m a t u r i t y ( p r o d u c t i o n of semen b y males or eggs b y females) was accelerated in males kept at 2 9 or 35 C and delayed in females at 35 C. N u m b e r of sperm per ejaculate and d u r a t i o n of fertility were reduced in males at 35 C. Females maintained at 35 C experienced significant decreases in egg p r o d u c t i o n , egg weight, and shell thickness b u t n o significant effect on fertility. Ingkasuwan and Ogasawara ( 1 9 6 6 ) f o u n d t h a t long day length (12 to 14 hr), high a m b i e n t t e m p e r a t u r e (32.2 C), and t h e interaction of t h e long light period and high t e m p e r a t u r e accelerated testes development and early semen p r o d u c t i o n in SCWL cockerels during 12 t o 27 weeks of age. T h e purpose of this s t u d y was to examine t h e reproductive p e r f o r m a n c e of broiler breeders exposed to cycling high t e m p e r a t u r e prior to sexual m a t u r i t y .
MATERIALS AND METHODS F o r t y male ( 2 0 b i r d s / c h a m b e r ) and 2 4 0 female ( 4 0 b i r d s / c h a m b e r ) broiler breeders were placed in cages (30.5 X 4 5 . 7 x 45.7 cm) (one male or two females per cage) within environmental chambers (2.4 X 3.2 X 2.3 m) at 14 weeks of age. Feed (14.0% protein and 3131 kcal/kg metabolizable energy [ M E ] ) was restricted to r e c o m m e n d e d levels, and water was provided ad libitum. C h a m b e r t e m p e r a t u r e s were maintained at 21.3 ± 2.5 C. Ventilation rate was a p p r o x i m a t e l y 4 7 . 2 liters/sec per chamber. Relative h u m i d i t y (RH) was uncontrolled and ranged from 4 0 to 50%. Light was provided from 0 6 0 0 t o 1800 hr with average light intensity at bird height equal to 28.3 lx. F r o m 17 to 20 weeks of age, control (C) chambers (one c h a m b e r of males and three chambers of females) were maintained at 21.0 + 1.4 C with 45 ± 5% R H . T e m p e r a t u r e in t h e o t h e r four chambers was cycled from 2 4 . 4 ± 5.5 C (45 ± 5% RH) during 1 8 0 0 to 0 8 0 0 hr to 36.0 ± 2.8 C (15 ± 5% R H ) during 0 8 0 0 to 1 8 0 0 hr. A m b i e n t t e m p e r a t u r e of the heattreated (HT) birds was initially increased 2.8 C / d a y until t h e u p p e r m e a n t e m p e r a t u r e was reached. At 18 and 2 0 weeks of age, blood samples and rectal b o d y t e m p e r a t u r e s were obtained
2
Omega Engineering Inc., Stanford, CT.
r a n d o m l y from five unfed birds per c h a m b e r (a t o t a l of 5 males and 15 females per t r e a t m e n t ) at 0 8 0 0 and 1400 hr. C h a m b e r t e m p e r a t u r e s of t h e H T birds were n o t increased until t h e 0 8 0 0 m e a s u r e m e n t s were completed on t h e sampling days ( a b o u t 1000 hr). Three to five milliliters of b l o o d were collected from t h e brachial vein with a 25 ga needle and heparinized syringe. Additional blood was collected from t h e v e n i p u n c t u r e for d e t e r m i n a t i o n of packed cell volume b y t h e m i c r o h e m a t o c r i t p r o c e d u r e , and blood smears were m a d e for d e t e r m i n a t i o n of differential leukocyte counts (Cook, 1 9 5 9 ) . Whole blood was k e p t in ice until removal of the plasma b y centrifugation ( 5 0 0 X g for 20 min at 4 C), and plasma was stored at —20 C until total plasma protein (Bradford, 1976) and glucose (Carroll et al, 1970) were d e t e r m i n e d . Rectal b o d y t e m p e r a t u r e was measured by inserting a general purpose thermister p r o b e 6 cm into t h e cloaca, and b o d y t e m p e r a t u r e s were recorded as t h e m a x i m u m reading from a digital t h e r m o m e t e r . 2 Blood samples and b o d y t e m p e r a t u r e s were o b t a i n e d within 3 min of handling birds. B o d y weights were obtained at biweekly intervals from 16 t o 20 weeks of age. O b servations were m a d e for daily feed c o n s u m p tion p a t t e r n s . Age of sexual m a t u r i t y was recorded for females as their first egg and for males by p r o d u c t i o n of semen after artificial ejaculation. F r o m 20 to 60 weeks of age, all birds were k e p t in individual cages in a house t h a t was fan ventilated and cooled with evaporative pads. M a x i m u m t e m p e r a t u r e never exceeded 30 C, and average R H was 65.0%. Feed (16.0% protein and 2 8 1 6 kcal/kg ME) was restricted to r e c o m m e n d e d levels for t h e hens and to 113.4 g/male per day. Water was supplied ad libitum, and light was provided from 0 4 0 0 to 1900 hr. B o d y weights were obtained at 4-week intervals. Egg p r o d u c t i o n was recorded 5 days per week (Monday t o F r i d a y ) , and average egg weights and specific gravities were calculated from eggs collected on 3 consecutive days at 4-week intervals. Males were ejaculated twice weekly (Tuesdays and T h u r s d a y s ) , and semen volume and concentration were measured weekly (Thursdays). Semen smears were m a d e , stained with eosin-nigrosin, and percentages of live, dead, and a b n o r m a l s p e r m a t o z o a determined (Lake and Stewart, 1 9 7 8 ) . Fertility among the t r e a t m e n t groups was d e t e r m i n e d b y collecting individual semen
HIGH TEMPERATURES AND BROILER BREEDER PERFORMANCE
1483
TABLE 1. Body temperatures (° C) of control (C) and heat-treated (HT) broiler breeders1 Males Age
Time
(wk)
(hr)
18
0800 1400
Females
C
HT
C
HT
41.74 x 41.50 x
41.66 x 41.36 x
41.59 x 41.29Y
41.55 x 41.42 x
SEM
.07
.12
0800 1400
20
41.72 x 41.44 x
SEM
41.92 x 41.30Y
41.60 x 41.25 x
.10
41.62 x 41.44 x .06
'"Means in columns within ages with different superscripts are significantly different (P<.05). 1
There were no significant differences between treatments within sexes and times (P>.05).
samples from C and HT males and inseminating one to three hens of each t r e a t m e n t with .05 ml of semen on t w o consecutive days. Eggs were collected for 12 days beginning o n t h e first day following t h e second insemination, set every 3 days, incubated 3 days, and examined for true fertility. Percent fertility was defined as number of fertile eggs per total n u m b e r of eggs incubated and d u r a t i o n of fertility as t h e last day of t h e collection period t h a t a fertile egg was p r o d u c e d . Data within sex were subjected to analysis of variance, and if significant t r e a t m e n t or time effects occurred, m e a n s were separated b y LSD ( P « . 0 5 ) (Snedecor and Cochran, 1967). T h e
arc-sin transformation of percentage d a t a was performed prior to analyses.
RESULTS AND DISCUSSION T h e r e were n o significant differences between t r e a t m e n t s for b o d y weight (data n o t s h o w n ) . G r o w t h rates and b o d y weights are generally depressed in young birds (4 weeks and older) grown in t e m p e r a t u r e s greater t h a n 2 9 C ( A d a m s and Rogler, 1 9 6 8 ; Deaton et ah, 1 9 7 8 ) , although Squibb et al. (1959) have shown t h a t r e d u c t i o n s in b o d y weight associated with high t e m p e r a t u r e s are caused by decreased feed intake and n o t t e m p e r a t u r e per se. Feed intake
TABLE 2. Hemaocrits of control (C) and beat-treated (HT) broiler breeders1 Male Age
Time
(wk)
(hr)
18
C
HT
C
HT
0800 1400
32.8 a 32.8 a
32.9 a 30.6 a
32.7 a 3 3.6 a
32.2 a 31.8 b
0800 1400
a
31.2 a 31.6 a
33. l a 32.7 a
31.5 b 30.7 b
SEM 20
SEM
Female
1.1
32.0 32.8 a
.5
a,b Means in rows within sexes with different superscripts are significantly different (P<.05). 1
There were no significant differences between times within sexes and treatments (P>.05).
0800 1400
18
6.8X 10.8X
1.2 X 1.4 X
2.4X 2.6X
.5
.9 .8X .8X
1.0 X 1.4 X
counts
3.0X 2.4X
1.8 X 2.0X
.9
.8 2.2X 3.8 X
1
58.8X 64.8X
58.4X 67.8X
C
8.8 ±1.3X
7.9 ±1.2X
8.7 ±1.2X
9.9 ±l.lx
HT
2.1 ±.6X 3.1 ±.6X
2.2 ±.4X 3.0 ±.5X
1.7 ±.4 X
2.5 + .4X
3.2 ±.5X
2.1 ±.5X
1.7 + .4X
C
3.0 + .6X
3.2 ±.6X
3.0 + .6X
1.9 ±.5X
HT
Basoph ils
70.5 ±2.2X
62.6 ±2.2X
70.1 ±2.5X
61.3 ±2.5X
C
There were no significant differences b e t w e e n t r e a t m e n t s within times ( P > . 0 5 ) .
male
(HT)
67.2 ±2.3X
66.1 ±2.2X
68.6 ±2.6X
66.6 ±2.4X
HT
fema
67.0X 50.6X
63.4X 57.6X
HT
L y m p h iocyt( : s ( L )
(%) of com trol (C) and heat-treated
2.7 ±.5X
HT
counts
2.4 ±.4X
2.8 ±.4X
C
Eosinophils
leukticyte
4.4
5.6
' " M e a n s ± SEM in c o l u m n s within ages with different superscripts are significantly different ( P < . 0 5 ) .
7.3 ±1.2X
1400
1400
9.9 ±1.2X
8.9 ±l.lx
0800
18
0800
8.9 ±l.lx
(hr)
(wk)
C
Monocytes
T A B L E 4 . Differential
(HT)
L y m p h o c y t e s (L)
(C) and heat-treated
3.0 X 3.4 X
HT
Basophils
(%) of control
There were no significant differences b etween t r e a t m e n t s with in times ( P > . 0 5 ) .
Time
20
2.5
1.6
7.4X 8.4 X
HT
Eosinophils
leukocyte
' ^ M e a n s in c o l u m n s within ages with different superscripts are significantly different ( P < . 0 5 ) .
7.4X 11.0X
8.0 X 12.2X
HT
Monocytes
Age
1
x
SEM
20
0800 1400
(hr)
(wk)
SEM
Time
Age
T A B L E 3. Differential
HIGH TEMPERATURES AND BROILER BREEDER PERFORMANCE T A B L E 5. Plasma glucose
(mg/dl)
of control
(C) and heat-treated
(HT) broiler
Males Age
Time
(wk)
(hr)
18 20
1485 breeders
Females
C
HT
C
HT
0800 1400
209.2 ± 5 . 1 a 184.9 ± 5.1 a .y
221.0 ± 5 . 1 a ' x 186.0 ± 5.1 a >y
206.4 ± 5.0a.x 200.1 ± 5 . 0 a . x
2 0 4 . 0 ± 5.0 a > x 185.6 ± 5.2 a >y
0800 1400
231.9 ± 5 . 2 a . x 171.4 ± 5 . 2 b . y
233.5 ± 5 . 8 a . x 2 0 0 . 0 + 5.2 a >y
210.4 ± 3.6a.x 191.8 + 3.6 a .y
208.3 + 3 . 5 a - x 185.7 + 3.7 a .y
a,b Means ± SEM in rows within sexes with different superscripts are significantly different (P<.05). '^Means ± SEM in columns within ages with different superscripts are significantly different (P<.05).
was restricted t o maintain r e c o m m e n d e d b o d y weights of t h e controls. T h e heat-treated birds were fed a m o u n t s equal t o t h a t given to controls, and b o t h groups consumed their feed at similar rates while t h e y were in t h e chambers (i.e., birds were normally fed at 0 8 0 0 hr, and all feed was consumed by 1 0 0 0 h r ) . T h e r e were n o significant differences between t r e a t m e n t s within sampling times for b o d y t e m p e r a t u r e (Table 1). Body temperatures were significantly reduced at 1400 h r compared t o 0 8 0 0 hr at 18 weeks of age for C females and at 20 weeks for H T males. This was m o s t likely caused by deprivation of feed, which will decrease b o d y t e m p e r a t u r e (Conner, 1 9 5 9 ; Hazelwood and Wilson, 1 9 6 2 ; Klandorf etal, 1981). It would seem t h a t t h e H T birds were able to maintain b o d y t e m p e r a t u r e at normal levels in a relatively warm dry e n v i r o n m e n t . Increases in b o d y t e m p e r a t u r e associated with increasing a m b i e n t t e m p e r a t u r e are d e p e n d e n t u p o n relative h u m i d i t y and t h e degree of acclimitization of t h e bird (Smith and Oliver, 1 9 7 1 ) .
Reece et al. ( 1 9 7 2 ) found t h a t m o r t a l i t y of 8-week-old broiler cockerels was significantly greater for birds exposed either t o 33 or 39% R H at 4 0 . 6 C t h a n birds k e p t at t h e same t e m p e r a t u r e with 17% R H . C o n s e q u e n t l y , h u m i d i t y is a criticial factor in determining heat stress in p o u l t r y . B o d y t e m p e r a t u r e acclimation requires 3 t o 5 days (Hillerman and Wilson, 1955), and F o x ( 1 9 5 1 ) suggested t h a t water c o n s u m p t i o n and its m o v e m e n t t h r o u g h t h e digestive tract m a y provide s u p p l e m e n t a r y t e m p e r a t u r e regulation. T h e HT birds used in this study were given adequate time for acclimitization, provided fresh water, and maintained at low h u m i d i t y levels during heat treatment. Under these conditions, b o d y t e m p e r a t u r e was unaffected. Hematocrits or percent packed cell volumes were significantly lower for H T females than controls during t h e afternoon sampling at 18 weeks and at b o t h times sampled at 20 weeks of age (Table 2). This was p r o b a b l y associated with h e m o d i l u t i o n caused b y elevated temp e r a t u r e (Huston, 1 9 6 5 ; K u b e n a et al., 1 9 7 2 ;
TABLE 6. Plasma protein (g/dl) of control (C) and heat-treated (HT) broiler breeders1 Males Age
Time
(wk)
(hr)
18 20
Females
C
HT
C
HT
0800 1400
6.4 ± . 5 a 6.4 + . 5 a
6.4 ± . 5 a 6.6 ± . 5 a
6.3 ± . 2 a 6.7 ± . 2 a
6.3 ± . 2 a 6.4 + . 2 a
0800 1400
6.2 ± . 2 a 6.4 + . 2 a
5.4 ± . 3 b 6.1 ± . 2 a
6.4 ± . 2 a 6.5 ± . 2 a
6.2 + . 2 a 5.6 + . 2 a
a ' b Means ± SEM in rows within sexes with different superscripts are significantly different (P<.05). 1
There were no significant differences between times within sexes and treatments (P>.05).
RENDEN AND McDANIEL
1486
Huggins and Lewis, 1 9 7 8 ) . There were no significant differences in h e m a t o c r i t s between t r e a t m e n t s for t h e males. Differential l e u k o c y c t e c o u n t s are s h o w n in Tables 3 and 4 for males and females, respectively. There were n o significant t e m p e r a t u r e effects on percentages of l e u k o c y t e cells. However, there were significant t i m e effects for percentages of heterophils in 18-week-old C pullets and for the ratio of l y m p h o c y t e s to heterophils in 18-week-old C males. It is n o t k n o w n w h y the percentage of heterophils was decreased or t h e l y m p h o c y t e to heterophil ratio increased with t i m e in these birds. Wolford and Ringer ( 1 9 6 2 ) suggested t h a t differential l e u k o c y t e counts could be used as a criterion for determining stress in p o u l t r y since stressors such as handling and feed deprivation for 4 0 hr resulted in significant increases in percentages of heterophils and decreases in percentages of l y m p h o c y t e s . T h a x t o n et al. (1967) reported t h a t acute or chronic heating ( 4 1 to 45 C) did n o t alter l e u k o c y t e c o u n t s in 3- to 4-week-old chicks, and it would seem t h a t the experimental conditions used in this s t u d y were n o t stressful according to t h e values in Tables 3 and 4.
35
40
WEEKS OF AGE
23
27
31
35
40
50
60
WEEKS OF AGE
FIG. 1. Semen volume (a), concentration (b), and total number of sperm per ejaculate (c) for control (C) and heat-treated (HT) broiler breeder males. *There was a significant difference (P<.05) between treatments for concentration during 28 to 31 weeks of age.
FIG. 2. Percentages of live, dead, and abnormal sperm for control (C) and heat-treated (HT) broiler breeder males. "There was a significant difference (P<.05) between treatments for percent abnormal sperm during 28 to 31 weeks of age.
HIGH TEMPERATURES AND BROILER BREEDER PERFORMANCE Plasma glucose was significantly greater in 20-week-old H T males t h a n controls during heat t r e a t m e n t , i.e., 1 4 0 0 h r (Table 5). Glucose levels were significantly lower in afternoon samples than in morning samples within all t r e a t m e n t s except 18-week-old C pullets. Heat stressing chickens has caused inconsistent changes in b l o o d glucose levels (Siegel, 1 9 7 1 ; McCormick et al, 1 9 7 9 ; Riesenfeld et al, 1980; Brake et al., 1 9 8 1 ; Ostrowski-Meissner, 1 9 8 1 ; Arad et al., 1 9 8 3 ) , and fasting of birds for 2 4 hr or longer has resulted in decreased (Lepkovsky et al, 1967; Langslow et al, 1970; Smith, 1 9 7 2 ; Nir et al, 1975) or unchanged (Belo et al, 1 9 7 6 ; F r e e m a n et al, 1 9 8 0 ; Hoshino et al, 1980) glucose concentrations. T o t a l plasma p r o t e i n was relatively stable for C and HT birds, although there was a significant difference between 20-week-old C and HT cockerels sampled at 0 8 0 0 hr (Table 6). O t h e r workers reported either no change (Squibb et al, 1 9 5 9 ; D e a t o n et al, 1969) or decreased (Vo et al, 1 9 7 8 ; Brake et al, 1 9 8 1 ; OstrowskiMeissner, 1981) total serum or plasma protein in chickens maintained above 32 C. There were no significant differences between t r e a t m e n t groups for age of sexual m a t u r i t y , p e r c e n t hen-day egg p r o d u c t i o n , egg weight and specific gravity, o r fertility (data n o t s h o w n ) . Sperm concentration and percent abnormal sperm were greater in HT males than controls during 28 t o 31 weeks of age (Figs. 1 and 2). It would seem t h a t t h e heat t r e a t m e n t conditions used in this study from 17 to 20 weeks of age had little or n o effect o n the subsequent reproductive performance of broiler breeders. T e m p e r a t u r e extremes, feed deprivation, water deprivation, and handling have been considered as i m p o r t a n t stressors in chickens ( F r e e m a n , 1 9 7 1 ) . S o m e of t h e physiological changes associated with stress are depressed growth, hemoconcentration, alterations in differential leukocyte counts (i.e., decreased l y m p h o c y t e s and increased heterophils), increased blood glucose and decreased total proteins, and possibly reduced reproductive capability in adults (Brown, 1 9 5 7 ; Brown, 1967; Siegel, 1 9 7 1 ; Wilson, 1 9 7 1 ; Siegel, 1980). Values for these m e a s u r e m e n t s from birds in this study would indicate t h a t t h e animals were n o t stressed. O t h e r workers (Beuving and V o n d e r , 1 9 7 8 ; Brake et al, 1981) have reported t h a t exposure to t e m p e r a t u r e s of 35 to 37 C d o n o t cause physiological stress. It has
1487
also been s h o w n t h a t t h e adverse effects of high t e m p e r a t u r e s o n r e p r o d u c t i o n can be avoided by providing a d e q u a t e time for acclimation to heat and suitable variations b e t w e e n high and low daily t e m p e r a t u r e s (Squibb et al, 1 9 5 9 ; D e a t o n et al, 1981). Heat per se was n o t deleterious t o i m m a t u r e broiler breeders in a low h u m i d i t y situation. T h e results of this study may be relevant to areas t h a t experience a warm, arid e n v i r o n m e n t and may n o t , however, apply t o h o t humid climates.
REFERENCES Adams, R. L., and J. C. Rogler, 1968. The effects of environmental temperature on the protein requirements and responses to energy in slow and fast growing chicks. Poultry Sci. 47:579—568. Arad, Z., J. Marder, and U. Eylath, 1983. Serum electrolyte and enzyme responses to heat stress and dehydration in the fowl (Gallus domesticus). Comp. Biochem. Physiol. 74A:449-453. Belo, P. S., D. R. Romos, and G. A. Leveille, 1976. Blood metabolites and glucose metabolism in the fed and fasted chicken. J. Nutr. 106:1135-1143. Beuving, G, and G. M. Vonder, 1978. Effect of stressing factors on corticosterone levels in plasma of laying hens. Gen. Comp. Endocrinol. 35:153 — 159. Bradford, M. A., 1976. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem. 72:248-254. Brake, J., J. D. Garlich, C. R. Parkhurst, P. Thaxton, and G. W. Morgan, 1981. Physiological profile of caged layers during one production season, molt, and postmolt: organ weights and blood constituents. Poultry Sci. 60:2157-2160. Brown, K. I., 1957. "Stress" and its implications in poultry production. World's Poult. Sci. J. 15: 255-276. Brown, K. I., 1967. Environmentally imposed stress. Pages 101 — 113 in Environmental Control in Poultry Production. T. C. Carter, ed. Oliver & Boyd, Ltd, London. Carroll, J. J., N. Smith, and A. L. Babson, 1970. A colorimetric serum glucose determination using hexokinase and glucose-6-phosphate dehydrogenase. Biochem. Med. 4:171—180. Cook, F. W., 1959. Staining fixed preparations of chicken blood cells with combination of MayGreenwald-Wright-Phloxine B stain. Avian Dis. 3:272-290. Conner, M. H., 1959. Effect of various hormone preparations and nutritional stresses in chicks. Poultry Sci. 38:1340-1343. Deaton, J. W., F. N. Reece, and W. J. Tarver, 1969. Hematocrit, hemoglobin and plasma-protein levels of broilers reared under constant temperatures. Poultry Sci. 48:1993-1996. Deaton, J. W., F. N. Reece, and J. G. McNaughton, 1978. The effect of temperature during the growing period on broiler performance. Poultry Sci. 57:1070-1074. Deaton, J. W., F. N. Reece, J. L. McNaughton, and B.
1488
RENDEN AND McDANIEL
D. Lott, 1981. Effect of differing temperature cycles on egg shell quality and layer performance. Poultry Sci. 60:733-737. Draper, M. H., and P. E. Lake, 1967. Physiological reactions of the laying fowl to adverse environments, with special reference to the defence reaction. Pages 87—100 in Environmental Control in Poultry Production. T. C. Carter, ed. Oliver & Boyd, Ltd., London. Fox, T. W., 1951. Studies on heat tolerance in the domestic fowl. Poultry Sci. 30:477-483. Freeman, B. M., 1971. Stress and the domestic fowl: A physiological appraisal. World's Poult. Sci. J. 27:263-275. Freeman, B. M., A. C. Manning, and I. H. Flack, 1980. Short term stressor effects of food withdrawal on the immature fowl. Comp. Biochem. Physiol. 67A: 5 6 9 - 5 7 1 . Hazelwood, R. L., and W. O. Wilson, 1962. Comparison of haematological alterations induced in the pidgeon and rat by fasting and heat stress. Comp. Biochem. Physiol. 7:211-219. Hillerman, J. P., and W. O. Wilson, 1955. Acclimation of adult chickens to environmental temperature changes. Am. J. Physiol. 180:591-595. Hoshino, S., M. Wakita, M. Suzuki, and K. Yamamoto, 1980. Effect of fasting on the levels of glucose, free fatty acids, growth hormone, and somatomedin in the serum, and on the pituitary function of the chicken. Jpn. Poult. Sci. 17: 329-336. Huggins, G., and R. W. Lewis, 1978. Precisely controlled temperature variations: Effect on hematocrit values of broiler and laying stock. Poultry Sci. 57:1463-1465. Huston, T. M., 1965. The influence of different environmental temperatures on immature fowl. Poultry Sci. 4 4 : 1 0 3 2 - 1036. Huston, T. M., and J. L. Carmon, 1958. Influence of high environmental temperature on fertility and hatchability of eggs of domestic fowl. Physiol. Zool. 31:232-235. Huston, T. M., W. P. Joiner, and J. L. Carmon, 1957. Breed differences in egg production of domestic fowl held at high envionmental temperatures. Poultry Sci. 36:1247-1254. Ingkasuwan, P., and F. X. Ogasawara, 1966. The effect of light and temperature and their interaction on the semen production of White Leghorn males. Poultry Sci. 45:1199-1206. Klandorf, H., P. J. Sharp, and M. G. Macleod, 1981. The relationship between heat production and concentrations of plasma thyroid hormones in the domestic hen. Gen. Comp. Endocrinol. 45:513-520. Kubena, L. F., J. D. May, F. N. Reece, and J. W. Deaton, 1972. Hematocrit and hemoglobin of broilers as influenced by environmental temperature and dietary iron level. Poultry Sci. 51:759-763. Lake, P. E., and J. M. Stewart, 1978. Artificial insemination in poultry. Min. Agric, Fisheries and Food. Bull. 213. Her Majesty's Stationery Office, London. Langslow, D. R., E. J. Butler, C. N. Hales, and A. W. Pearson, 1970. The response of plasma insulin, glucose and nonesterified fatty acids to various
hormones, nutrients and drugs in the domestic fowl. J. Endocrinol. 46:243-260. Lepkovsky, S., M. K. Dimick, F. Furuta, N. Snapir, R. Park, N. Narita, and K. Komatsu, 1967. Response of blood glucose and plasma free fatty acids to fasting and to injection of insulin and testosterone in chickens. Endocrinology 81:1001 — 1006. McCormick, C. C , J. D. Garlich, and F. W. Edens, 1979. Fasting and diet affect the tolerance of young chickens exposed to acute heat stress. J. Nutr. 109:1797-1809. Nir, I., D. Yam, and M. Perek, 1975. Effects of stress on the corticosterone content of the blood plasma and adrenal gland of intact and bursectomized Gallus domesticus. Poultry Sci. 54: 2101-2110. Ostrowski-Meissner, H. T., 1981. The physiological and biochemical responses of broilers exposed to short-term thermal stress. Comp. Biochem. Physiol. 7 0 A : l - 8 . Reece, F. N., J. W. Deaton, and L. F. Kubena, 1972. Effects of high temperature and humidity on heat prostration of broiler chickens. Poultry Sci. 51:2021-2025. Riesenfeld, G., A. Berman, and S. Hurwitz, 1980. Glucose kinetics and heat production in normothermic, hypothermic and hyperthermic fasted chickens. Comp. Biochem. Physiol. 67A:199— 202. Siegel, H. S., 1971. Adrenals, stress and the environment. World's Poult. Sci. J. 27:327-349. Siegel, H. S., 1980. Physiological stress in birds. Bioscience 30:529-534. Smith, A. J., and J. Oliver, 1971. Some physiological effects of high environmental temperatures on the laying hen. Poultry Sci. 50:912-925. Smith, C. J., 1972. Blood glucose levels in young chickens: The influence of light regimes. Poultry Sci. 51:268-273. Snedecor, G. W., and W. G. Cochran, 1967. Statistical Methods. 6th ed. Iowa State Univ. Press, Ames, IA. Squibb, R. L., M. A. Guzman, and N. S. Scrimshaw, 1959. Growth and blood constituents of immature New Hampshire fowl exposed to constant temperature of 99° F for 7 days. Poultry Sci. 38:220-221. Thaxton, P., C. R. Sadler, and B. Glick, 1967. The physiological response of New Hampshires to high temperatures. Poultry Sci. 46:1598-1599. Vo, K. V., M. A. Boone, B. L. Hughes, and J. F. Knechtges, 1980. Effects of ambient temperature on sexual maturity in chickens. Poultry Sci. 59:2532-2537. Vo, K. V., M. A. Boone, and W. E. Johnston, 1978. Effect of three lifetime ambient temperatures on growth, feed and water consumption, and various blood components in male and female Leghorn chickens. Poultry Sci. 57:798-807. Wilson, W. O., 1971. Evaluation of stressor agents in domestic animals. J. Anim. Sci. 32:578—583. Wolford, J. H., and R. K. Ringer, 1962. Adrenal weight, adrenal ascorbic acid, adrenal cholesterol and differential leucocyte counts as physiological indicators of "stressor" agents in laying hens. Poultry Sci. 41:1521-1529.
1 Alabama Agricultural Experiment Station Journal Series No. 12-83507.
New Hampshires (NH) and White P l y m o u t h R o c k s (WPR) maintained at high t e m p e r a t u r e . Egg weight, b o d y weight, and feed c o n s u m p tion were decreased for all three breeds at 32.2 C. H u s t o n and Carmon ( 1 9 5 8 ) m a i n t a i n e d SCWL hens and SCWL, NH and WPR males from hatching through the first laying year at either 32.2 C or a m b i e n t t e m p e r a t u r e . Fertility of hens k e p t at ambient t e m p e r a t u r e was significantly greater t h a n fertility of t h e heat treated hens. There were n o significant differences among male t r e a t m e n t g r o u p s for fertility, although there were significant breed differences. Matings b e t w e e n birds k e p t in similar environments had higher fertility t h a n matings between birds in different environm e n t s . T h e r e were no differences in h a t c h ability a m o n g any of t h e mating g r o u p s . V o et al. ( 1 9 8 0 ) maintained male and female SCWL chickens at one of t h r e e c o n s t a n t temperatures ( 2 1 , 2 9 , or 35 C) from 2 t o 33 weeks
1481
1482
RENDEN AND McDANIEL
of age. Sexual m a t u r i t y ( p r o d u c t i o n of semen b y males or eggs b y females) was accelerated in males kept at 2 9 or 35 C and delayed in females at 35 C. N u m b e r of sperm per ejaculate and d u r a t i o n of fertility were reduced in males at 35 C. Females maintained at 35 C experienced significant decreases in egg p r o d u c t i o n , egg weight, and shell thickness b u t n o significant effect on fertility. Ingkasuwan and Ogasawara ( 1 9 6 6 ) f o u n d t h a t long day length (12 to 14 hr), high a m b i e n t t e m p e r a t u r e (32.2 C), and t h e interaction of t h e long light period and high t e m p e r a t u r e accelerated testes development and early semen p r o d u c t i o n in SCWL cockerels during 12 t o 27 weeks of age. T h e purpose of this s t u d y was to examine t h e reproductive p e r f o r m a n c e of broiler breeders exposed to cycling high t e m p e r a t u r e prior to sexual m a t u r i t y .
MATERIALS AND METHODS F o r t y male ( 2 0 b i r d s / c h a m b e r ) and 2 4 0 female ( 4 0 b i r d s / c h a m b e r ) broiler breeders were placed in cages (30.5 X 4 5 . 7 x 45.7 cm) (one male or two females per cage) within environmental chambers (2.4 X 3.2 X 2.3 m) at 14 weeks of age. Feed (14.0% protein and 3131 kcal/kg metabolizable energy [ M E ] ) was restricted to r e c o m m e n d e d levels, and water was provided ad libitum. C h a m b e r t e m p e r a t u r e s were maintained at 21.3 ± 2.5 C. Ventilation rate was a p p r o x i m a t e l y 4 7 . 2 liters/sec per chamber. Relative h u m i d i t y (RH) was uncontrolled and ranged from 4 0 to 50%. Light was provided from 0 6 0 0 t o 1800 hr with average light intensity at bird height equal to 28.3 lx. F r o m 17 to 20 weeks of age, control (C) chambers (one c h a m b e r of males and three chambers of females) were maintained at 21.0 + 1.4 C with 45 ± 5% R H . T e m p e r a t u r e in t h e o t h e r four chambers was cycled from 2 4 . 4 ± 5.5 C (45 ± 5% RH) during 1 8 0 0 to 0 8 0 0 hr to 36.0 ± 2.8 C (15 ± 5% R H ) during 0 8 0 0 to 1 8 0 0 hr. A m b i e n t t e m p e r a t u r e of the heattreated (HT) birds was initially increased 2.8 C / d a y until t h e u p p e r m e a n t e m p e r a t u r e was reached. At 18 and 2 0 weeks of age, blood samples and rectal b o d y t e m p e r a t u r e s were obtained
2
Omega Engineering Inc., Stanford, CT.
r a n d o m l y from five unfed birds per c h a m b e r (a t o t a l of 5 males and 15 females per t r e a t m e n t ) at 0 8 0 0 and 1400 hr. C h a m b e r t e m p e r a t u r e s of t h e H T birds were n o t increased until t h e 0 8 0 0 m e a s u r e m e n t s were completed on t h e sampling days ( a b o u t 1000 hr). Three to five milliliters of b l o o d were collected from t h e brachial vein with a 25 ga needle and heparinized syringe. Additional blood was collected from t h e v e n i p u n c t u r e for d e t e r m i n a t i o n of packed cell volume b y t h e m i c r o h e m a t o c r i t p r o c e d u r e , and blood smears were m a d e for d e t e r m i n a t i o n of differential leukocyte counts (Cook, 1 9 5 9 ) . Whole blood was k e p t in ice until removal of the plasma b y centrifugation ( 5 0 0 X g for 20 min at 4 C), and plasma was stored at —20 C until total plasma protein (Bradford, 1976) and glucose (Carroll et al, 1970) were d e t e r m i n e d . Rectal b o d y t e m p e r a t u r e was measured by inserting a general purpose thermister p r o b e 6 cm into t h e cloaca, and b o d y t e m p e r a t u r e s were recorded as t h e m a x i m u m reading from a digital t h e r m o m e t e r . 2 Blood samples and b o d y t e m p e r a t u r e s were o b t a i n e d within 3 min of handling birds. B o d y weights were obtained at biweekly intervals from 16 t o 20 weeks of age. O b servations were m a d e for daily feed c o n s u m p tion p a t t e r n s . Age of sexual m a t u r i t y was recorded for females as their first egg and for males by p r o d u c t i o n of semen after artificial ejaculation. F r o m 20 to 60 weeks of age, all birds were k e p t in individual cages in a house t h a t was fan ventilated and cooled with evaporative pads. M a x i m u m t e m p e r a t u r e never exceeded 30 C, and average R H was 65.0%. Feed (16.0% protein and 2 8 1 6 kcal/kg ME) was restricted to r e c o m m e n d e d levels for t h e hens and to 113.4 g/male per day. Water was supplied ad libitum, and light was provided from 0 4 0 0 to 1900 hr. B o d y weights were obtained at 4-week intervals. Egg p r o d u c t i o n was recorded 5 days per week (Monday t o F r i d a y ) , and average egg weights and specific gravities were calculated from eggs collected on 3 consecutive days at 4-week intervals. Males were ejaculated twice weekly (Tuesdays and T h u r s d a y s ) , and semen volume and concentration were measured weekly (Thursdays). Semen smears were m a d e , stained with eosin-nigrosin, and percentages of live, dead, and a b n o r m a l s p e r m a t o z o a determined (Lake and Stewart, 1 9 7 8 ) . Fertility among the t r e a t m e n t groups was d e t e r m i n e d b y collecting individual semen
HIGH TEMPERATURES AND BROILER BREEDER PERFORMANCE
1483
TABLE 1. Body temperatures (° C) of control (C) and heat-treated (HT) broiler breeders1 Males Age
Time
(wk)
(hr)
18
0800 1400
Females
C
HT
C
HT
41.74 x 41.50 x
41.66 x 41.36 x
41.59 x 41.29Y
41.55 x 41.42 x
SEM
.07
.12
0800 1400
20
41.72 x 41.44 x
SEM
41.92 x 41.30Y
41.60 x 41.25 x
.10
41.62 x 41.44 x .06
'"Means in columns within ages with different superscripts are significantly different (P<.05). 1
There were no significant differences between treatments within sexes and times (P>.05).
samples from C and HT males and inseminating one to three hens of each t r e a t m e n t with .05 ml of semen on t w o consecutive days. Eggs were collected for 12 days beginning o n t h e first day following t h e second insemination, set every 3 days, incubated 3 days, and examined for true fertility. Percent fertility was defined as number of fertile eggs per total n u m b e r of eggs incubated and d u r a t i o n of fertility as t h e last day of t h e collection period t h a t a fertile egg was p r o d u c e d . Data within sex were subjected to analysis of variance, and if significant t r e a t m e n t or time effects occurred, m e a n s were separated b y LSD ( P « . 0 5 ) (Snedecor and Cochran, 1967). T h e
arc-sin transformation of percentage d a t a was performed prior to analyses.
RESULTS AND DISCUSSION T h e r e were n o significant differences between t r e a t m e n t s for b o d y weight (data n o t s h o w n ) . G r o w t h rates and b o d y weights are generally depressed in young birds (4 weeks and older) grown in t e m p e r a t u r e s greater t h a n 2 9 C ( A d a m s and Rogler, 1 9 6 8 ; Deaton et ah, 1 9 7 8 ) , although Squibb et al. (1959) have shown t h a t r e d u c t i o n s in b o d y weight associated with high t e m p e r a t u r e s are caused by decreased feed intake and n o t t e m p e r a t u r e per se. Feed intake
TABLE 2. Hemaocrits of control (C) and beat-treated (HT) broiler breeders1 Male Age
Time
(wk)
(hr)
18
C
HT
C
HT
0800 1400
32.8 a 32.8 a
32.9 a 30.6 a
32.7 a 3 3.6 a
32.2 a 31.8 b
0800 1400
a
31.2 a 31.6 a
33. l a 32.7 a
31.5 b 30.7 b
SEM 20
SEM
Female
1.1
32.0 32.8 a
.5
a,b Means in rows within sexes with different superscripts are significantly different (P<.05). 1
There were no significant differences between times within sexes and treatments (P>.05).
0800 1400
18
6.8X 10.8X
1.2 X 1.4 X
2.4X 2.6X
.5
.9 .8X .8X
1.0 X 1.4 X
counts
3.0X 2.4X
1.8 X 2.0X
.9
.8 2.2X 3.8 X
1
58.8X 64.8X
58.4X 67.8X
C
8.8 ±1.3X
7.9 ±1.2X
8.7 ±1.2X
9.9 ±l.lx
HT
2.1 ±.6X 3.1 ±.6X
2.2 ±.4X 3.0 ±.5X
1.7 ±.4 X
2.5 + .4X
3.2 ±.5X
2.1 ±.5X
1.7 + .4X
C
3.0 + .6X
3.2 ±.6X
3.0 + .6X
1.9 ±.5X
HT
Basoph ils
70.5 ±2.2X
62.6 ±2.2X
70.1 ±2.5X
61.3 ±2.5X
C
There were no significant differences b e t w e e n t r e a t m e n t s within times ( P > . 0 5 ) .
male
(HT)
67.2 ±2.3X
66.1 ±2.2X
68.6 ±2.6X
66.6 ±2.4X
HT
fema
67.0X 50.6X
63.4X 57.6X
HT
L y m p h iocyt( : s ( L )
(%) of com trol (C) and heat-treated
2.7 ±.5X
HT
counts
2.4 ±.4X
2.8 ±.4X
C
Eosinophils
leukticyte
4.4
5.6
' " M e a n s ± SEM in c o l u m n s within ages with different superscripts are significantly different ( P < . 0 5 ) .
7.3 ±1.2X
1400
1400
9.9 ±1.2X
8.9 ±l.lx
0800
18
0800
8.9 ±l.lx
(hr)
(wk)
C
Monocytes
T A B L E 4 . Differential
(HT)
L y m p h o c y t e s (L)
(C) and heat-treated
3.0 X 3.4 X
HT
Basophils
(%) of control
There were no significant differences b etween t r e a t m e n t s with in times ( P > . 0 5 ) .
Time
20
2.5
1.6
7.4X 8.4 X
HT
Eosinophils
leukocyte
' ^ M e a n s in c o l u m n s within ages with different superscripts are significantly different ( P < . 0 5 ) .
7.4X 11.0X
8.0 X 12.2X
HT
Monocytes
Age
1
x
SEM
20
0800 1400
(hr)
(wk)
SEM
Time
Age
T A B L E 3. Differential
HIGH TEMPERATURES AND BROILER BREEDER PERFORMANCE T A B L E 5. Plasma glucose
(mg/dl)
of control
(C) and heat-treated
(HT) broiler
Males Age
Time
(wk)
(hr)
18 20
1485 breeders
Females
C
HT
C
HT
0800 1400
209.2 ± 5 . 1 a 184.9 ± 5.1 a .y
221.0 ± 5 . 1 a ' x 186.0 ± 5.1 a >y
206.4 ± 5.0a.x 200.1 ± 5 . 0 a . x
2 0 4 . 0 ± 5.0 a > x 185.6 ± 5.2 a >y
0800 1400
231.9 ± 5 . 2 a . x 171.4 ± 5 . 2 b . y
233.5 ± 5 . 8 a . x 2 0 0 . 0 + 5.2 a >y
210.4 ± 3.6a.x 191.8 + 3.6 a .y
208.3 + 3 . 5 a - x 185.7 + 3.7 a .y
a,b Means ± SEM in rows within sexes with different superscripts are significantly different (P<.05). '^Means ± SEM in columns within ages with different superscripts are significantly different (P<.05).
was restricted t o maintain r e c o m m e n d e d b o d y weights of t h e controls. T h e heat-treated birds were fed a m o u n t s equal t o t h a t given to controls, and b o t h groups consumed their feed at similar rates while t h e y were in t h e chambers (i.e., birds were normally fed at 0 8 0 0 hr, and all feed was consumed by 1 0 0 0 h r ) . T h e r e were n o significant differences between t r e a t m e n t s within sampling times for b o d y t e m p e r a t u r e (Table 1). Body temperatures were significantly reduced at 1400 h r compared t o 0 8 0 0 hr at 18 weeks of age for C females and at 20 weeks for H T males. This was m o s t likely caused by deprivation of feed, which will decrease b o d y t e m p e r a t u r e (Conner, 1 9 5 9 ; Hazelwood and Wilson, 1 9 6 2 ; Klandorf etal, 1981). It would seem t h a t t h e H T birds were able to maintain b o d y t e m p e r a t u r e at normal levels in a relatively warm dry e n v i r o n m e n t . Increases in b o d y t e m p e r a t u r e associated with increasing a m b i e n t t e m p e r a t u r e are d e p e n d e n t u p o n relative h u m i d i t y and t h e degree of acclimitization of t h e bird (Smith and Oliver, 1 9 7 1 ) .
Reece et al. ( 1 9 7 2 ) found t h a t m o r t a l i t y of 8-week-old broiler cockerels was significantly greater for birds exposed either t o 33 or 39% R H at 4 0 . 6 C t h a n birds k e p t at t h e same t e m p e r a t u r e with 17% R H . C o n s e q u e n t l y , h u m i d i t y is a criticial factor in determining heat stress in p o u l t r y . B o d y t e m p e r a t u r e acclimation requires 3 t o 5 days (Hillerman and Wilson, 1955), and F o x ( 1 9 5 1 ) suggested t h a t water c o n s u m p t i o n and its m o v e m e n t t h r o u g h t h e digestive tract m a y provide s u p p l e m e n t a r y t e m p e r a t u r e regulation. T h e HT birds used in this study were given adequate time for acclimitization, provided fresh water, and maintained at low h u m i d i t y levels during heat treatment. Under these conditions, b o d y t e m p e r a t u r e was unaffected. Hematocrits or percent packed cell volumes were significantly lower for H T females than controls during t h e afternoon sampling at 18 weeks and at b o t h times sampled at 20 weeks of age (Table 2). This was p r o b a b l y associated with h e m o d i l u t i o n caused b y elevated temp e r a t u r e (Huston, 1 9 6 5 ; K u b e n a et al., 1 9 7 2 ;
TABLE 6. Plasma protein (g/dl) of control (C) and heat-treated (HT) broiler breeders1 Males Age
Time
(wk)
(hr)
18 20
Females
C
HT
C
HT
0800 1400
6.4 ± . 5 a 6.4 + . 5 a
6.4 ± . 5 a 6.6 ± . 5 a
6.3 ± . 2 a 6.7 ± . 2 a
6.3 ± . 2 a 6.4 + . 2 a
0800 1400
6.2 ± . 2 a 6.4 + . 2 a
5.4 ± . 3 b 6.1 ± . 2 a
6.4 ± . 2 a 6.5 ± . 2 a
6.2 + . 2 a 5.6 + . 2 a
a ' b Means ± SEM in rows within sexes with different superscripts are significantly different (P<.05). 1
There were no significant differences between times within sexes and treatments (P>.05).
RENDEN AND McDANIEL
1486
Huggins and Lewis, 1 9 7 8 ) . There were no significant differences in h e m a t o c r i t s between t r e a t m e n t s for t h e males. Differential l e u k o c y c t e c o u n t s are s h o w n in Tables 3 and 4 for males and females, respectively. There were n o significant t e m p e r a t u r e effects on percentages of l e u k o c y t e cells. However, there were significant t i m e effects for percentages of heterophils in 18-week-old C pullets and for the ratio of l y m p h o c y t e s to heterophils in 18-week-old C males. It is n o t k n o w n w h y the percentage of heterophils was decreased or t h e l y m p h o c y t e to heterophil ratio increased with t i m e in these birds. Wolford and Ringer ( 1 9 6 2 ) suggested t h a t differential l e u k o c y t e counts could be used as a criterion for determining stress in p o u l t r y since stressors such as handling and feed deprivation for 4 0 hr resulted in significant increases in percentages of heterophils and decreases in percentages of l y m p h o c y t e s . T h a x t o n et al. (1967) reported t h a t acute or chronic heating ( 4 1 to 45 C) did n o t alter l e u k o c y t e c o u n t s in 3- to 4-week-old chicks, and it would seem t h a t the experimental conditions used in this s t u d y were n o t stressful according to t h e values in Tables 3 and 4.
35
40
WEEKS OF AGE
23
27
31
35
40
50
60
WEEKS OF AGE
FIG. 1. Semen volume (a), concentration (b), and total number of sperm per ejaculate (c) for control (C) and heat-treated (HT) broiler breeder males. *There was a significant difference (P<.05) between treatments for concentration during 28 to 31 weeks of age.
FIG. 2. Percentages of live, dead, and abnormal sperm for control (C) and heat-treated (HT) broiler breeder males. "There was a significant difference (P<.05) between treatments for percent abnormal sperm during 28 to 31 weeks of age.
HIGH TEMPERATURES AND BROILER BREEDER PERFORMANCE Plasma glucose was significantly greater in 20-week-old H T males t h a n controls during heat t r e a t m e n t , i.e., 1 4 0 0 h r (Table 5). Glucose levels were significantly lower in afternoon samples than in morning samples within all t r e a t m e n t s except 18-week-old C pullets. Heat stressing chickens has caused inconsistent changes in b l o o d glucose levels (Siegel, 1 9 7 1 ; McCormick et al, 1 9 7 9 ; Riesenfeld et al, 1980; Brake et al., 1 9 8 1 ; Ostrowski-Meissner, 1 9 8 1 ; Arad et al., 1 9 8 3 ) , and fasting of birds for 2 4 hr or longer has resulted in decreased (Lepkovsky et al, 1967; Langslow et al, 1970; Smith, 1 9 7 2 ; Nir et al, 1975) or unchanged (Belo et al, 1 9 7 6 ; F r e e m a n et al, 1 9 8 0 ; Hoshino et al, 1980) glucose concentrations. T o t a l plasma p r o t e i n was relatively stable for C and HT birds, although there was a significant difference between 20-week-old C and HT cockerels sampled at 0 8 0 0 hr (Table 6). O t h e r workers reported either no change (Squibb et al, 1 9 5 9 ; D e a t o n et al, 1969) or decreased (Vo et al, 1 9 7 8 ; Brake et al, 1 9 8 1 ; OstrowskiMeissner, 1981) total serum or plasma protein in chickens maintained above 32 C. There were no significant differences between t r e a t m e n t groups for age of sexual m a t u r i t y , p e r c e n t hen-day egg p r o d u c t i o n , egg weight and specific gravity, o r fertility (data n o t s h o w n ) . Sperm concentration and percent abnormal sperm were greater in HT males than controls during 28 t o 31 weeks of age (Figs. 1 and 2). It would seem t h a t t h e heat t r e a t m e n t conditions used in this study from 17 to 20 weeks of age had little or n o effect o n the subsequent reproductive performance of broiler breeders. T e m p e r a t u r e extremes, feed deprivation, water deprivation, and handling have been considered as i m p o r t a n t stressors in chickens ( F r e e m a n , 1 9 7 1 ) . S o m e of t h e physiological changes associated with stress are depressed growth, hemoconcentration, alterations in differential leukocyte counts (i.e., decreased l y m p h o c y t e s and increased heterophils), increased blood glucose and decreased total proteins, and possibly reduced reproductive capability in adults (Brown, 1 9 5 7 ; Brown, 1967; Siegel, 1 9 7 1 ; Wilson, 1 9 7 1 ; Siegel, 1980). Values for these m e a s u r e m e n t s from birds in this study would indicate t h a t t h e animals were n o t stressed. O t h e r workers (Beuving and V o n d e r , 1 9 7 8 ; Brake et al, 1981) have reported t h a t exposure to t e m p e r a t u r e s of 35 to 37 C d o n o t cause physiological stress. It has
1487
also been s h o w n t h a t t h e adverse effects of high t e m p e r a t u r e s o n r e p r o d u c t i o n can be avoided by providing a d e q u a t e time for acclimation to heat and suitable variations b e t w e e n high and low daily t e m p e r a t u r e s (Squibb et al, 1 9 5 9 ; D e a t o n et al, 1981). Heat per se was n o t deleterious t o i m m a t u r e broiler breeders in a low h u m i d i t y situation. T h e results of this study may be relevant to areas t h a t experience a warm, arid e n v i r o n m e n t and may n o t , however, apply t o h o t humid climates.
REFERENCES Adams, R. L., and J. C. Rogler, 1968. The effects of environmental temperature on the protein requirements and responses to energy in slow and fast growing chicks. Poultry Sci. 47:579—568. Arad, Z., J. Marder, and U. Eylath, 1983. Serum electrolyte and enzyme responses to heat stress and dehydration in the fowl (Gallus domesticus). Comp. Biochem. Physiol. 74A:449-453. Belo, P. S., D. R. Romos, and G. A. Leveille, 1976. Blood metabolites and glucose metabolism in the fed and fasted chicken. J. Nutr. 106:1135-1143. Beuving, G, and G. M. Vonder, 1978. Effect of stressing factors on corticosterone levels in plasma of laying hens. Gen. Comp. Endocrinol. 35:153 — 159. Bradford, M. A., 1976. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem. 72:248-254. Brake, J., J. D. Garlich, C. R. Parkhurst, P. Thaxton, and G. W. Morgan, 1981. Physiological profile of caged layers during one production season, molt, and postmolt: organ weights and blood constituents. Poultry Sci. 60:2157-2160. Brown, K. I., 1957. "Stress" and its implications in poultry production. World's Poult. Sci. J. 15: 255-276. Brown, K. I., 1967. Environmentally imposed stress. Pages 101 — 113 in Environmental Control in Poultry Production. T. C. Carter, ed. Oliver & Boyd, Ltd, London. Carroll, J. J., N. Smith, and A. L. Babson, 1970. A colorimetric serum glucose determination using hexokinase and glucose-6-phosphate dehydrogenase. Biochem. Med. 4:171—180. Cook, F. W., 1959. Staining fixed preparations of chicken blood cells with combination of MayGreenwald-Wright-Phloxine B stain. Avian Dis. 3:272-290. Conner, M. H., 1959. Effect of various hormone preparations and nutritional stresses in chicks. Poultry Sci. 38:1340-1343. Deaton, J. W., F. N. Reece, and W. J. Tarver, 1969. Hematocrit, hemoglobin and plasma-protein levels of broilers reared under constant temperatures. Poultry Sci. 48:1993-1996. Deaton, J. W., F. N. Reece, and J. G. McNaughton, 1978. The effect of temperature during the growing period on broiler performance. Poultry Sci. 57:1070-1074. Deaton, J. W., F. N. Reece, J. L. McNaughton, and B.
1488
RENDEN AND McDANIEL
D. Lott, 1981. Effect of differing temperature cycles on egg shell quality and layer performance. Poultry Sci. 60:733-737. Draper, M. H., and P. E. Lake, 1967. Physiological reactions of the laying fowl to adverse environments, with special reference to the defence reaction. Pages 87—100 in Environmental Control in Poultry Production. T. C. Carter, ed. Oliver & Boyd, Ltd., London. Fox, T. W., 1951. Studies on heat tolerance in the domestic fowl. Poultry Sci. 30:477-483. Freeman, B. M., 1971. Stress and the domestic fowl: A physiological appraisal. World's Poult. Sci. J. 27:263-275. Freeman, B. M., A. C. Manning, and I. H. Flack, 1980. Short term stressor effects of food withdrawal on the immature fowl. Comp. Biochem. Physiol. 67A: 5 6 9 - 5 7 1 . Hazelwood, R. L., and W. O. Wilson, 1962. Comparison of haematological alterations induced in the pidgeon and rat by fasting and heat stress. Comp. Biochem. Physiol. 7:211-219. Hillerman, J. P., and W. O. Wilson, 1955. Acclimation of adult chickens to environmental temperature changes. Am. J. Physiol. 180:591-595. Hoshino, S., M. Wakita, M. Suzuki, and K. Yamamoto, 1980. Effect of fasting on the levels of glucose, free fatty acids, growth hormone, and somatomedin in the serum, and on the pituitary function of the chicken. Jpn. Poult. Sci. 17: 329-336. Huggins, G., and R. W. Lewis, 1978. Precisely controlled temperature variations: Effect on hematocrit values of broiler and laying stock. Poultry Sci. 57:1463-1465. Huston, T. M., 1965. The influence of different environmental temperatures on immature fowl. Poultry Sci. 4 4 : 1 0 3 2 - 1036. Huston, T. M., and J. L. Carmon, 1958. Influence of high environmental temperature on fertility and hatchability of eggs of domestic fowl. Physiol. Zool. 31:232-235. Huston, T. M., W. P. Joiner, and J. L. Carmon, 1957. Breed differences in egg production of domestic fowl held at high envionmental temperatures. Poultry Sci. 36:1247-1254. Ingkasuwan, P., and F. X. Ogasawara, 1966. The effect of light and temperature and their interaction on the semen production of White Leghorn males. Poultry Sci. 45:1199-1206. Klandorf, H., P. J. Sharp, and M. G. Macleod, 1981. The relationship between heat production and concentrations of plasma thyroid hormones in the domestic hen. Gen. Comp. Endocrinol. 45:513-520. Kubena, L. F., J. D. May, F. N. Reece, and J. W. Deaton, 1972. Hematocrit and hemoglobin of broilers as influenced by environmental temperature and dietary iron level. Poultry Sci. 51:759-763. Lake, P. E., and J. M. Stewart, 1978. Artificial insemination in poultry. Min. Agric, Fisheries and Food. Bull. 213. Her Majesty's Stationery Office, London. Langslow, D. R., E. J. Butler, C. N. Hales, and A. W. Pearson, 1970. The response of plasma insulin, glucose and nonesterified fatty acids to various
hormones, nutrients and drugs in the domestic fowl. J. Endocrinol. 46:243-260. Lepkovsky, S., M. K. Dimick, F. Furuta, N. Snapir, R. Park, N. Narita, and K. Komatsu, 1967. Response of blood glucose and plasma free fatty acids to fasting and to injection of insulin and testosterone in chickens. Endocrinology 81:1001 — 1006. McCormick, C. C , J. D. Garlich, and F. W. Edens, 1979. Fasting and diet affect the tolerance of young chickens exposed to acute heat stress. J. Nutr. 109:1797-1809. Nir, I., D. Yam, and M. Perek, 1975. Effects of stress on the corticosterone content of the blood plasma and adrenal gland of intact and bursectomized Gallus domesticus. Poultry Sci. 54: 2101-2110. Ostrowski-Meissner, H. T., 1981. The physiological and biochemical responses of broilers exposed to short-term thermal stress. Comp. Biochem. Physiol. 7 0 A : l - 8 . Reece, F. N., J. W. Deaton, and L. F. Kubena, 1972. Effects of high temperature and humidity on heat prostration of broiler chickens. Poultry Sci. 51:2021-2025. Riesenfeld, G., A. Berman, and S. Hurwitz, 1980. Glucose kinetics and heat production in normothermic, hypothermic and hyperthermic fasted chickens. Comp. Biochem. Physiol. 67A:199— 202. Siegel, H. S., 1971. Adrenals, stress and the environment. World's Poult. Sci. J. 27:327-349. Siegel, H. S., 1980. Physiological stress in birds. Bioscience 30:529-534. Smith, A. J., and J. Oliver, 1971. Some physiological effects of high environmental temperatures on the laying hen. Poultry Sci. 50:912-925. Smith, C. J., 1972. Blood glucose levels in young chickens: The influence of light regimes. Poultry Sci. 51:268-273. Snedecor, G. W., and W. G. Cochran, 1967. Statistical Methods. 6th ed. Iowa State Univ. Press, Ames, IA. Squibb, R. L., M. A. Guzman, and N. S. Scrimshaw, 1959. Growth and blood constituents of immature New Hampshire fowl exposed to constant temperature of 99° F for 7 days. Poultry Sci. 38:220-221. Thaxton, P., C. R. Sadler, and B. Glick, 1967. The physiological response of New Hampshires to high temperatures. Poultry Sci. 46:1598-1599. Vo, K. V., M. A. Boone, B. L. Hughes, and J. F. Knechtges, 1980. Effects of ambient temperature on sexual maturity in chickens. Poultry Sci. 59:2532-2537. Vo, K. V., M. A. Boone, and W. E. Johnston, 1978. Effect of three lifetime ambient temperatures on growth, feed and water consumption, and various blood components in male and female Leghorn chickens. Poultry Sci. 57:798-807. Wilson, W. O., 1971. Evaluation of stressor agents in domestic animals. J. Anim. Sci. 32:578—583. Wolford, J. H., and R. K. Ringer, 1962. Adrenal weight, adrenal ascorbic acid, adrenal cholesterol and differential leucocyte counts as physiological indicators of "stressor" agents in laying hens. Poultry Sci. 41:1521-1529.