ENVIRONMENTAL ADAPTATION
the Veterinary Science Department and of Dr. Neeti R. Bohidar, Department of Applied Statistics. REFERENCES
Hutchinson, J. C. D., and A. H. Sykes, 1953. Physiological acclimatization of fowls to a hot, humid environment. J. Agr. Sci. 43 . 294-322. Kheireldin, M. A., and C. S. Shaffner, 1957. Familial differences in resistance to high environmental temperatures in chicks. Poultry Sci. 36: 1334-1339. Mueller, W. J., 1961. The effect of constant and fluctuating environmental temperatures in the biological performance of laying pullets. Poultry Sci. 40: 1562-1571. Smith, W. M., Jr., and G. H. Long, 1959. Effect of environment versus breeding on farm flock incidence of visceral lymphomatosis. J. Amer. Vet. Med. Assoc. 134: 373-376. Squibb, R. L., 1959. Relation of diurnal temperature and humidity ranges to egg production and feed efficiency of New Hampshire hens. J. Agr. Sci. 52: 217-222. Thornton, P. A., and R. E. Moreng, 1959. Further evidence in the value of ascorbic acid for maintenance of shell quality in warm environmental temperature. Poultry Sci. 38: 594-599.
Light Environment as a Factor in Growth and Feed Efficiency of Meat-Type Chickens W. L. BEANE, P. B. SIEGEL AND H. S. SIEGEL Virginia Polytechnic Institute, Blacksburg (Received for publication December 18, 1964)
N
UMEROUS investigations have demonstrated that meat-type chickens exposed to continuous light are heavier at broiler age than those given periods of light and darkness (e.g. Moore, 1957; Shutze et al., 1960; Krueger et aZ.,1962; Beane et al., 1962). Data obtained by the above investigators suggest that, although there are diurnal rhythms in feeding activity (Siegel and Guhl, 1956; Siegel et al., 1962), continuous illumination provides an advantage of increased feeding time for chickens with a rapid growth potential. This advantage was shown by Siegel and Wood (1964) who found that under continuous light chicks restricted in feeding
time weighed less than those fed ad libitum. If however, the sole function of light, in the maximum expression of juvenile growth, is through the facilitation of time for food consumption, then growth at several light intensities during a day should be comparable to that at a single intensity. Shutze et al. (1962), however, have shown that growth was different between flocks provided continuous artificial light and those given natural plus artificial illumination for continuous light. The experiments reported here were designed to compare the growth of meat-type chickens under continuous light at single
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Campos, A. C , F. H. Wilcox and C. S. Shaffner, 1960. The influence of fast and slow rises in ambient temperature on production traits and mortality of laying pullets. Poultry Sci. 39: 119-129. Clark, C. E., H. Nikoopour and C. I. Draper, 1963. Effects of temperature on egg production. Utah Farm and Home Sci. 24: 91, 105-106. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Hays, F. A., 1958. Laying house temperature and egg production. Poultry Sci. 37: 592-595. Huston, T. M., W. P. Joiner and J. L. Carmon, 1957. Breed differences in egg production of domestic fowl held at high environmental temperatures. Poultry Sci. 36: 1247-1254.
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intensities, continuous light at two intensities and periods of light and darkness.
S.
SIEGEL
means, Duncan's test was applied.
(1955) multiple range
RESULTS AND DISCUSSION The stock-light regime interactions for body weight were not significant in three of the four analyses. The exception being at three weeks of age in Experiment 1. This interaction, although significant accounted for only about two percent of the total variation and was thus considered unimportant. Because stocks were intermingled and feed consumption was measured on a pen basis the role of the stock-light regime interaction could not be determined for efficiency of feed utilization. No significant differences were found between stocks for either body weight or feed efficiency. The data therefore were pooled for presentation in Table 1. This table contains means and standard deviations of body weights and feed efficiency at three and nine weeks of age in each experiment. Cockerels exposed to continuous illumination (H, L, and HL) were significantly heavier at three weeks of age than those exposed to intervals of light and darkness ( H D ) . Comparisons at this age among continuous illumination treatments revealed, in Experiment 1, that broilers reared under a single light intensity were significantly heavier than those maintained at a varying intensity ( H L ) . In Experiment 2 these differences were not significant. Comparisons between chickens exposed to either high or low intensities throughout showed no significant difference at three weeks of age in either experiment. At nine weeks of age, chickens provided with continuous illumination were significantly heavier than those maintained under the H D regime; an effect consistent to that found at three weeks. At the older age the significant weight advantage of those exposed to continuous illumination at a single intensity over those maintained
1. 24 hours continuous illumination with high intensity ( H ) , 2. 24 hours continuous illumination with low intensity (L), 3. 24 hours continuous illumination with 8 hours at high intensity and 16 hours at the low intensity ( H L ) , 4. 8 hours continuous illumination at high intensity and 16 hours of darkness ( H D ) . Light intensity, in lux at bird level within the pens, ranged from 8.07 to 51.67 for the high intensity and 0.6S to 1.61 for the low intensity. Each range was within a treatment unit and was due to uneven distribution of light throughout a pen. All pens were darkened and all illumination was artificial from a bulb located in the center of the ceiling. There were 120 males in each of two replicated light-treatment pens within each experiment for a total of 960 birds per experiment. Cockerels from two commercial broiler crosses were intermingled at about 1.25 ft.2 of floor space per chick started. Chicks were fed a commercial broiler ration in crumble form from trough feeders. Feeder space allowances in linear inches per chick started were 1.5 to three weeks of age and 3.0 thereafter. Body weights on an individual bird basis and feed consumption by pens were obtained at three and nine weeks of age. Data were analyzed by a factorial analysis of variance within ages and, when significant differences were found between
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EXPERIMENTAL PROCEDURE Two experiments were conducted; the first commenced May 14, 1963 and the second May 29, 1964. Procedures were the same for both experiments. Light regimes were:
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LIGHT AND GROWTH TABLE 1.—Means and standard deviations of body weights and feed efficiencies Light treatments (hours and intensities) Experiment
Period (wks.)
1
0-3 0-9
365+ 48" 1,716+153°
Body weights (g.) 370+ 45" 336+ 50b 1,785 +138 d 1,684+141 b
297+ 40" 1,637 + 155"
2
0-3 0-9
366+ 57b 1,820+166"
365+ 56 b 1,808 + 172"
376+ 49 b 1,716+ 178b
309+ 53" 1,634 ±166"
1
0-3 0-9
.749+.012" .482+.002"
2
0-3 0-9
.753+.012" .498+.006"
H 24 high
L 24 low
HL 8 high: 16 low
Feed efficiency (g. live wt./g. feed) .716+.006" .667+.032" .479+.002" .475+.004" .747+.Oil" .503+.009"
.725+.015" .487+.005"
HD 8 high: 16 dark
.690+.05 7" .488+.003" .699+.038" .496+.001"
under the HL regime was consistent in both experiments. Males reared at the lower light intensity were significantly heavier than those at the higher intensity in Experiment 1, while in the second experiment no difference was found between these regimes. Differences between light regimes for feed efficiency were not significant at three and nine weeks of age in either experiment. The results of these experiments show that meat-type chickens exposed to continuous illumination have a more rapid juvenile growth than those given periods of darkness and are consistent with the findings of Moore (1957), Shutze et al. (1960), Krueger et al. (1962) and Beane et al. (1962). If the effect of continuous illumination is solely to enable these faster growing birds additional time for the consumption of food then differences between single and varying light intensities should not be prevalent provided illumination is continuous. Our results, however, demonstrate that growth rate is greater when continuous illumination is provided at a single intensity rather than at two intensities. This suggests the involvement of factors other than
feeding time. Shutze et al. (1960) noted similar results when the natural photoperiod was extended by artificial illumination. The results from the experiment reported here showed further that under continuous illumination where intensity was not varied within treatment, a higher light intensity did not increase the growth over that obtained from a lower intensity. This indicates that within the range utilized, light intensity was not of major importance. One might speculate that under continuous illumination at a single light intensity the birds develop a feeding schedule or rhythm which is not complicated by varying periods of light intensities and allows for a maximization of their growth potential. Under the high-low intensity a diurnal rhythm may be expressed during which there may be extended periods of time when food is not consumed. If this behavioral response is under neural control it might not be as great when the change is from a higher to a lower light intensity as from a higher intensity to complete darkness. In terms of broiler production, the experiments point out a problem inherent in the management of artificial light in houses
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Any two means in a row with the same superscript are not significantly different (P < .05).
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with windows which allow the entrance of natural light. Relatively high intensity entering during daylight hours is supplanted with relatively low intensity artificial light at night. Results in such flocks thus may not be comparable with flocks maintained in continuous low intensity light in a windowless house. SUMMARY
Beane, W. L., P. B. Siegel and H. S. Siegel, 1962. The effect of light on body weight and feed conversion of broilers. Poultry Sci. 4 1 : 1350-1351. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11 :l-42. Krueger, W. F., C. B. Ryan, W. 0. Cawley and J. H. Quisenbery, 1962. Artificial light and number of daily feedings on performance of broilers. Proc. Assoc. So. Agr. Wks. 60: 316. Moore, C. H., 1957. The effect of light on growth of broiler chickens. Poultry Sci. 36: 1142-1143. Shultze, J. V., L. S. Jensen, J. S. Carver and W. E. Matson, 1960. Influence of various lighting regimes on the performance of broiler chickens. Washington Agr. Expt. Sta. Tech. Bui. 36. Siegel, H. S. and G. W. Wood, 1964. Length of daily feeding time as an influence on growth and digestive efficiency in young chickens. Poultry Sci. 43 : 406-410. Siegel, P. B. and A. M. Guhl, 1956. The measurement of some diurnal rhythms in the activity of White Leghorn cockerels. Poultry Sci. 35: 1340-1345. Siegel, P. B., W. L. Beane and C. Y. Kramer, 1962. The measurement of feeding activity in chickens to eight weeks of age. Poultry Sci. 4 1 : 1419-1422.
Fish Meal Studies 1. EFFECTS OF LEVELS AND SOURCES ON BROILER GROWTH RATE AND FEED EFFICIENCY 1 P. W. WALDROUP, P. VAN WALLEGHEM, JACK L. FRY, C. CHICCO AND R. H. HARMS Florida Agricultural Experiment Stations, Gainesville, Florida (Received far publication December 18, 1964)
data have been acCONSIDERABLE cumulated concerning the value of fish meal as an ingredient for broiler diets. 1
Fla. Agri. Exp. Sta. Journal Series No. 1854.
The literature concerning the use of fish meal has been extensively reviewed by Menge et al. (1952), Branion and Hill (1953), Rasmussen et al. (1957), and Harms et al. (1961).
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Two experiments were conducted with meat-type stocks in an effort to compare the effects of continuous illumination at single light intensities to those with varying light intensities and/or periods of light and darkness. Stock-light regime interactions were found to be unimportant with regard to body weight at three and nine weeks of age. Birds reared under continuous illumination weighed more at these ages than those provided with periods of darkness. Further, those maintained under either a single high or low light intensity were heavier than those subjected to varying intensities. No differences were obtained between light regimes for feed efficiency.
REFERENCES