Research/PIC Project 176
From Poultry Hub
Project title:Effects of midnight feeding on the bone density and egg quality of brown and white table egg layers. (Canadian Poultry Magazine July 2008)
Project Leader/s: Crystal Riczu & Doug Korver
Organisation/s: Poultry Research Centre, University of Alberta.
Contents |
Project overview
Much research has been conducted examining the process of shell calcification and bone mineralization in poultry. Extensive studies have also investigated ways to improve both egg and bone quality through such methods as nutrition, feeding schedules, lighting schedules, and housing. Unfortunately, it is difficult to prevent the age-dependent decrease in egg quality and bone quality that occurs during the production cycle of laying hens. Not only is this a welfare concern for the hen, but an important economic concern to commercial egg producers in terms of bird and egg losses. Although hens will consume feed in anticipation of the lights going off at night, most of the feed will have passed through the digestive tract well before the lights come on in the morning or before the next feeding. Since shell calcification takes approximately 20-23 hours, a majority of this process occurs while there is very little, if any, dietary calcium left in the digestive tract. If intestinal calcium absorption can not meet shell formation requirements, minerals are mobilized from the bone. The practice of midnight feeding involves turning on the lights for an hour at midnight. This gives the bird a chance to eat allowing them to increase the amount of calcium coming directly from the digestive tract, which can then be used for eggshell formation. This reduces the overall calcium demands on the bone, which results in a reduced risk of mobilizing critical structural bone near the end of lay. Read full report
Research
The objective of this study was to investigate if feeding program (conventional versus midnight feeding) and strain (white versus brown) would have an effect on body weight, feed intake, egg production and quality and bone mineralization. Since dietary calcium has been shown to be a better source of calcium for eggshell formation than that mobilized from the bone, it was hypothesized that the additional intake during the nocturnal period provided by midnight feeding should have a positive impact on egg and bone quality. We also expected that brown layers would have larger body size, higher intake, and better egg quality compared to white layers, as described by the primary breeder management guide. At 18 wks of age, Lohmann LSL-Lite and 64 Lohmann Brown (64 of each) hens were randomly selected and housed individually in one of four light-tight rooms. Each room had 16 birds of each strain. Two of the rooms received conventional 15L:9D (0500 h to 2000 h) feeding schedule (control feeding(CF) program), whereas the other two rooms received an additional hour of light at midnight (0000 h to 0100h)daily until the end of the experiment (midnight feeding (MF) program). The experiment ran to 67 wk of age; daily hen/day egg production, weekly feed intake were collected. Body weights, daily pattern of feed intake(from 0500 h to 2000 h), and night time intake (from 2000 h to 0500 h), as well as egg and bone quality measurements were measured throughout the trial. Bone quality was determined by analysing total, trabecular, and cortical densities and cross-sectional areas of the right tibiotarsus of a subset of the birds using quantitative computed tomography (Riczu et al. 2004). No feeding effects or feeding by strain interactions were found on body weight, but the brown layers had aconsistently higher body weight than white layers (P . 0.0001). The initial introduction of midnight feeding increased intake for both strains early in production, which was expected as such a transition in diet can increase intake up to 2-4 % before birds become adapted. The larger body mass of brown layers resulted in significantly higher daytime, nighttime and daily intake at most ages throughout the trial.The CF birds had higher daytime feed consumption (P . 0.0026) whereas MF birds had a greater nighttime consumption (P .0.0001); overall there was no effect on total daily feed intake. Prior to 46 wk of age, the brown hens consumed more feed than the white hens. After that time, the effect of strain on feed intake was greatly diminished. It is interesting to note that some of the control birds consumed feed during the dark hours. No differences due to strain or feeding program were seen in total egg production and marketable egg production. Midnight feeding birds had higher total and settable egg production during 19 and 20 wk of age (P = 0.0457), although this was not significant for overall production. Although feeding and feeding by strain interaction effects on age at first egg were not significant, the differences in body weight between strains, may have contributed to the earlier age at first egg and initial (18 to 21 wk) greater weekly (%) egg production seen in the brown laying strain compared to the white laying stain (P . 0.0019). This is supported by the observations that sexual maturity is primarily determined by body weight, in that heavier brown strains typically come into production sooner than the lighter white strain for laying. MF birds had a shorter prime sequence length than the Control birds, however there were no differences due to feeding program in total or saleable egg production over the course of the experiment. MF had no effect on any of the bone parameters measured. The white hens tended to have greater and total tibiotarsus cortical bone density throughout the trial, but lower cross sectional area than the brown hens.Read full report
The Bottom Line
In the present study, midnight feeding did not improve the skeletal health of the birds, egg production, nor quality parameters. The lack of osteoporosis in the control birds of each strain may indicate that the birds were not at risk for this problem. Anecdotal evidence from the industry suggests that, like modern broilers that have been selected for reduced incidence of metabolic disease even as growth rates continue to increase, modern laying hens may have been selected for both decreased skeletal problems and high levels of production. Although the results of the present study suggest that MF may not be useful at the present time, continued selection pressure for increased egg production means that osteoporosis (caged layer fatigue) is likely to become an issue in the future. Producers should monitor the health of their birds closely, and consider implementing MF if the birds appear to be developing osteoporosis. However, in the absence of an overt problem, MF does not appear to be beneficial.Read full report
Source
Poultry Industry Council
- 483 Arkell Road, Guelph, Ontario,Canada, N1H 6H8.
- pic@poultryindustrycouncil.ca
- http://www.poultryindustrycouncil.caEgg industry
