Hourly water consumption and egg formation in the domestic fowl

Corticosterone metabolites in laying hen droppings-Effects of fiber enrichment, genotype, and daily variations

There is growing interest and concern for animal welfare in commercial poultry production. To evaluate stress and welfare in an objective and noninvasive way, fecal corticosterone metabolites (FCM) in droppings can be analyzed. However, the influence of diet, genotype, and daily variations in FCM and production of droppings in laying hens has been poorly investigated. This study examined the effect of insoluble fiber by adding 3% ground straw pellets to the feed to Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) hens housed in furnished cages between 20 and 40 wk of age. In total, 960 hens were included in the study. Droppings were collected 4 times per day for 3 consecutive days and analyzed by corticosterone immunoassay. Biological validation confirmed the ability of the assay to detect changes in FCM levels. Inclusion of straw pellets in the feed increased FCM concentration in both hen genotypes and increased excretion rate of FCM in LB hens. The LB hens also produced greater amounts of droppings than LSL hens. Both FCM levels and production of droppings varied during the day, although no distinct diurnal rhythm was found. These findings demonstrate that when using FCM to evaluate stress and welfare in laying hens, many factors (e.g., diet, genotype used, and so on) need to be taken into account to allow accurate interpretation of the results. In addition, under certain conditions, excretion rate of FCM might be more appropriate to use compared with FCM concentration.

Behavioural adaptation of laying hens to dilution of diets under mash and pellet form

1. Two laying diets, control (A) and a low-energy (B) diet diluted by adding 450 g/kg wheat bran, were fed to semi-heavy hens in three different forms: mash, small pellets and large pellets. The behavioural adaptations and the production characteristics for these six regimens were studied on 72 individually caged hens, between 19 and 29 weeks of age, subjected to a lighting pattern of 14 h light/24 h. 2. Diet B, as mash, showed a lower apparent physical density than the others. The hardness and durability of the pelleted diets were similar. 3. Hens fed the mash diet B could not completely adjust their food intake to compensate for the dilution and showed reduced egg output and body weight gain compared to the other groups. 4. Video observation of each hen for 14 consecutive hours showed that mash-fed hens ate for longer periods than pellet-fed hens during the first 11 h (proportion of time spent eating: 41.3% mash B, 32.5% mash A and 20% to 25% for all the pelleted diets). These differences were less pronounced during the last 3 h of the photoperiod. 5. Trough-oriented stereotypies were noted in 14 out of 22 mash-fed hens and in 12 out of 47 pellet-fed hens. Dilution of the diet did not appear to exacerbate stereotyped behaviours under the conditions of the study. 6. This experiment demonstrates that the feeding behaviour of laying hens is affected by the physical characteristics of the diet and that this may lower their productivity. 7. Low-energy pelleted diets might be used to feed hens efficiently in tropical countries where cereal by-products are abundant.

Influence of wet and dry feed on laying hens under heat stress

Two experiments were carried out with a split-plot design over time using White Leghorn hens, 161 days of age. The experiments were conducted to determine the effect of two ambient temperatures (21.1 versus 29.4 C in Experiment 1 and 21.1 versus 33.3 C in Experiment 2) on feed and water consumption using four dietary regimens. The day was divided into two feeding periods: a.m. (0600 to 1300 h) and p.m. (1300 to 0600 h the next morning). The four regimens were as follows: dry feed during both a.m. and p.m. periods; dry feed during a.m. period and wet feed (50% moisture) during the p.m. period; wet feed in the a.m. and dry feed in the p.m.; and wet feet during both a.m. and p.m. periods. The hens were maintained on a 14 h light: 10 h dark lighting program. The hens consumed the greatest quantity of DM and water during the p.m. period, regardless of the environmental temperature to which the hens were exposed. Constant heat stress at 29.4 and 33.3 increased (P less than or equal to .05) drinking water intake during the a.m. but not during the p.m. period. The use of wet feed and dry-wet feed provided a 38 and 48% increase (P less than or equal to .05), respectively, in DM intake when compared with the use of dry feed at 33.3 C. Exposure of laying hens to high environmental temperatures (29.4 and 33.3 C) decreased (P less than or equal to .05) albumen and shell weight; yolk weight was depressed only at 33.3 C. The use of wet feed (50% moisture), ad libitum, or in the p.m. stimulated DM intake at 33.3 C.

Effect of dietary calcium levels near the time of sexual maturity on water intake and excreta moisture content

Three trials were conducted to investigate the effect of dietary calcium on water balance of leghorn pullets. Trial 1 involved introduction of a 4% calcium layer diet at 112, 123, 134, or 144 days of age. Introducing the layer diet early had an early but transitory effect on water intake (P less than .05) and absolute quantity of excreta moisture, although the pattern of percentage excreta moisture was not clearly defined. In a second trial, birds were moved to laying cages at 105 days, with diet change from 1 to 4% calcium occurring at 112 or 142 days. When the layer diet was offered at 112 days, percentage excreta moisture was higher from 113 to 142 days, although no difference was seen after this time. In a final experiment, introduction of a 4% calcium layer diet at either 112 or 133 days of age resulted in higher percentage excreta moisture at four measurement periods to 245 days of age, although this effect was significant only at 147 days (P less than .05). These results suggest there is a transitory effect of dietary calcium on water intake and excreta moisture content. This affect may be of concern within controlled environment buildings and with certain manure-handling systems. In commercial situations, such dietary changes are often confounded with increased dietary protein concentration, another factor known to influence water balance in pullets.

Activities of amylase, trypsin and lipase in the pancreas and small intestine of the laying hen during egg formation

1. During a cycle of 14 h artificial light and 10 h darkness, dry matter and enzyme concentrations were measured in the pancreas and gut of egg-forming hens. 2. Dry or fresh pancreas weight did not show significant variation but pancreatic enzyme activities increased gradually from 2 to 22 h after oviposition. 3. Total wet and dry matter contents of the small intestine gradually increased from 2 to 18 h after oviposition and then decreased significantly. Intestinal tryptic activity followed the same pattern whereas intestinal amylase gradually decreased from 2 h after oviposition; intestinal lipase activity tended to decrease during the light period (2 to 10 h after oviposition) and to increase during the dark period (14 to 22 h after oviposition). 4. By contrast, patterns of enzyme activity in the pancreas were similar. It is proposed that modification of the chyme and transit rates during the day may affect pancreatic enzyme fate and distribution in the small intestine. 5. In non-egg-forming birds intestinal contents and enzyme activities were less than in egg-forming birds. The reverse was observed in the case of the pancreas where contents and enzyme activities were increased. A relationship with food intake pattern is discussed.

Composition of crop and gizzard contents in the laying hen

Crop and gizzard contents were analysed at six stages of egg formation. 2. The crop was empty during the day and full during the night while the gizzard contained a constant amount of dry matter. The water content of the crop did not change but that of the gizzard was at a minimum just after the ovulation and at a maximum 18 h later. 3. The osmotic pressure of the gizzard contents remained constant and close to that of the blood; that of the crop contents was almost isotonic at oviposition but hypertonic 18 h later. In both organs the pH of the liquid phase varied cyclicly with the egg formation and was lowest during egg shell deposition. 4. The Na+, K+ and Cl- contents of the crop liquid phase did not vary but Ca2+ increased with decreasing pH.Na+ and K+ were also constant in the gizzard liquid phase but Cl- and Ca2+ increased during shell formation. 5. It is concluded that the amount of HCl secreted by the proventiculus is related to egg shell deposition and that calcium solubilisation depends on microbial fermentation in crop and HCl secretion by proventriculus.