A study was conducted to evaluate four different cholecalciferol levels (NRC; modified), using diets supplemented with 200 (control), 1500, 2500 or 3500 IU/kg of cholecalciferol (VIT-D3). Each treatment was assigned to 3 pens of 17 broiler chicks of a commercial strain grown in an open-sided house with sidewall curtains. At 21 and 42 days, BW and feed conversion (FCR) were determined. At 42 days, five birds per pen were slaughtered to evaluate tibia and toe ash of the right leg, and incidence and severity of tibial dyschondroplasia (TD) of the left tibia and also measured dressing percentage and breast meat yield. Serum calcium and phosphorus concentrations were also determined. Haemagglutination inhibition antibody titre against Newcastle disease virus and lymphoid organs weight/body weight ratio were also determined. At both 21 and 42 days, the BW of birds fed 1500 IU/kg to 3500 IU/kg of VIT-D3 was significantly greater than birds fed 200 IU/kg. Similarly, better FCR was observed in birds those fed diets of high level of VIT-D3. No significant difference was observed for mortality at any age. Better dressing percentage and breast meat yield were noted in birds fed diets containing 2500 or 3500 IU/kg VIT-D3. Both tibia and toe ash contents were increased (p < 0.05) progressively with increased concentrations of cholecalciferol in feed. The incidence of TD (percentage of birds having TD scores greater than zero) was significantly (p < 0.05) influenced by level of 3500 IU VIT-D3/kg at 42 days. The severity of TD in birds fed diets containing 200 IU/kg VIT-D3 was apparently higher than birds fed diets with higher levels of VIT-D3. Concentrations of calcium and phosphorus minerals in the serum increased progressively with the high level of VIT-D3 supplementation to birds at both 21 and 42 days of age. Feeding levels of 1500 or 3500 IU of vitamin D3 did positively affect the immune system within the parameters measured. It may be concluded that performance, bone mineralization, blood chemistry and immunity against disease in broilers could be maintained when supplementing high level of VIT-D3 incorporated in broiler diets.

A study was conducted to evaluate three different probiotics, using drinking water supplemented with protexin, biovet and yoghurt. The day old broiler chicks were randomly divided into 12 separate floor pens each comprising 25 birds and three pens (replicates) per treatment group following completely randomised design. At 28 and 39 days of age body weight (BW) and feed to gain ratio (FCR) were determined. At the end of experiment, nine birds per treatment were sacrificed to evaluate carcass characteristics, abdominal fat contents and the internal organs. Blood haemato-biochemical parameters were determined. Haemagglutination inhibition antibody titres against Newcastle disease virus and lymphoid organs weight/body weight ratio were also determined. The BW of birds given probiotics was significantly greater than control (without probiotics) at both 28 and 39 days of age. Similarly, better FCR was observed in birds those given drinking water with probiotics. There was less mortality recorded with probiotics treatments. Differences in carcass characteristics, organs weight, meat composition and haematological values among all the treatments were non-significant. However, abdominal fat contents reduced significantly in probiotics supplemented groups as compared to control and cholesterol contents were reduced significantly supplemented groups as compared to control at both 21 and 39 days of age. Feeding of probiotics did positively affect the immune system within the parameters measured. It may be concluded that performance, blood chemistry, immunity against disease and economic efficiency in broilers could be maintained when supplementing any probiotic incorporated in broiler's drinking water.

1. Two experiments were conducted to examine time of oviposition for hens exposed to continuous dim lighting, to dim lighting alternating with bright lighting in a 24 h cycle or to a mixed system using bright light, dim light and darkness. 2. Under continuous dim lighting (0.3 lux), the pattern of ovipositions was the same as that reported previously for constant darkness, more eggs being laid around midnight than around noon. 3. With alternating bright and dim phases, mean time of lay was approximately 16 h after the transition from bright to dim lighting, which was 3 h earlier than under the corresponding cycle of light and dark. This phase advance was the same whether the bright:dim ratio was 16:1 or 160:1. 4. Dim lighting (1.25 lux) preceded by a period of normal lighting (5 lux or 50 lux) and followed by 8 h darkness was treated as part of the photoperiod. 5. It is concluded that, when there is no darkness, a period of dim lighting is treated as darkness, provided the contrast between bright and dim phases is sufficient. However, when darkness, dim light and bright light are all included in a cycle, the dim light is treated as part of the photoperiod, even though there may be a contrast between the brightly lit and dimly lit phases which, in the absence of darkness, would cause the dim phase to be treated as dark.

1. Two short-term trials are described in which laying hens were exposed to 8 h light followed by 8 one-min pulses of light at hourly intervals followed by 8 h darkness (8L:8i:8D). The effect of varying the intensity of illumination during the one-min pulses and the effect of placing the intermittent lighting before the 8 h photoperiod (8i:8L:8D), were studied. 2. Normal egg production was maintained by the 8L:8i:8D system when the light pulses were at 20 lux, but not at 5 lux. This suggests a minimum threshold for illumination with short light pulses higher than that needed for continuous lighting. 3. Time of lay under 8L:8i:8D was the same as with 8L:16D in relation to the beginning and ending of the 8 h main photoperiod, but with 8i:8L:8D mean time of lay was 2 to 3 h earlier. Thus the hourly pulses caused a phase advance when placed before the normal photoperiod but did not cause a phase delay when placed after the normal photoperiod.