ABSTRACT
In each of two trials a 2 x 2 factorial arrangement of treatments was used to evaluate the growth response of tom turkeys to environmental light. The main experimental light treatment factors were: daylength [23 h light (L):1 h dark (D) vs. 8 h L:16 h D] and light intensity (10.8 lx vs. 108 lx). There were 100 toms in each treatment; all birds were in closed confinement floor pens exposed to artificial light only. Data were collected for growth performance evaluations at 2 to 4-wk intervals to 22 wk of age. No significant daylength x intensity interactions occurred in the study. No consistent effect of daylength or light intensity on body weight occurred. Light intensity had no significant effect on feed conversion but 23 h L:1 h D significantly (P less than or equal to .01) improved feed conversion from that in the 8 h L:16 h D treatment at 18 and 22 wk of age. This occurred in both trials. Neither the daylength nor the light intensity treatment effects differed with regard to livability or to incidence of leg disorders. Testicular development at 22 wk of age of birds in the two intensity treatments was similar but testes were significantly (P less than .01) larger in the 23 h L:1 h D treatment than the 8 h L:16 h D treatment. Percentage of breast yield was not influenced significantly by the daylength or intensity treatments but the amount of abdominal fat was significantly greater in the 8 h L:16 h D group than the 23 h L:1 h D group. From the results of this study it seems clear that daylength can have an important impact on the growth performance of tom turkeys whereas variations in light intensity ranging from 10.8 to 108 lx generally resulted in negligible differences in response.
Subject(s)
Light , Turkeys/growth & development , Animals , Circadian Rhythm , Eating , Leg/abnormalities , Lighting , Male , Organ Size , Random Allocation , Testis/growth & development , Weight GainABSTRACT
Two trials were completed that examined the effects of light intensity on poult performance, adrenal weight, and ocular size during the first 2 weeks after hatching. In both trials the treatments started on the day of hatching and consisted of 23 hr of light per day of either 1.1, 11, 110, or 220 lx intensity from incandescent bulbs. A light intensity of 1.1 lx, but not 11, 110, or 220 lx, had an adverse effect on poult performance as indicated by significantly smaller body weights, reduced feed intake, and increased mortality in both trials. In addition, the poults in the 1.1 lx treatment group had significantly enlarged eyes in both trials and significantly greater adrenal weights in Trial 2 than the other treatment groups. It was concluded that low light intensity of 1.1 lx resulted in poor poult performance, and this was accompanied by an altered morphology of the eyes and the adrenal gland.
Subject(s)
Adrenal Glands/anatomy & histology , Body Weight , Eye/anatomy & histology , Light , Turkeys/physiology , Animals , Male , Mortality , Organ Size , Turkeys/anatomy & histologyABSTRACT
The growth performance of tom turkeys maintained in closed and open confinement housing was examined. Treatments were initiated on the day of hatching and consisted of constant light intensity of 1, 11, 110, or 220 lx in an enclosed house or sunlight supplemented with 11 or 220 lx at night in an open-sided house; all treatments received a total of 23 hr of light each day (23L:1D). Body weight, feed conversion, mortality, leg abnormalities, and final testes weight were recorded. Growth performance at marker age was not significantly different among treatments except for a heavier 18-week body weight in the open-confinement group given sunlight only (DL) and, in the closed confinement, a better feed conversion in the 11 lx treatment (C11) than the 1 lx treatment (C1) at 22 weeks of age. There was no apparent relationship between light intensity level and leg abnormalities but 22-week testes weight increased as light intensity increased. It was concluded that within closed confinement a constant light intensity of 1 lx resulted in an inferior growth performance, whereas 11 lx was sufficient to allow a growth performance similar to that obtained with 110 or 220 lx. In open confinement, supplemental artificial light at night of 11 or 220 lx did not result in an improved growth performance from birds on natural daylengths.
Subject(s)
Light , Turkeys/growth & development , Animals , Body Weight , Energy Metabolism , Male , Mortality , Sexual Maturation , Turkeys/physiologyABSTRACT
In each of two studies the influence of light intensity on the eye morphology of poults was examined. The light intensity treatments were started on the day of hatching and consisted of 1.1, 11, 110, or 220 lx from incandescent bulbs for 23 hr each day. Eye weight, anterior-posterior diameter, and transverse diameter were significantly increased only in the 1.1 lx treatment of both tests. Under the conditions of this test it was concluded that eye morphology of poults can be changed by low light intensity of 1.1 lx but not 11, 110, or 220 lx.
