The effect of changing the excreta moisture of caged laying hens on the excreta and microbial contamination of their egg shells

1. An experiment that included 1440 caged laying hens in 24 experimental units was conducted to determine the effect of differences in excreta moisture on the proportion of dirty eggs and the microbial contamination of eggs that were ostensibly uncontaminated by excreta. Excreta moisture contents were changed by giving the hens diets that contained 4 different concentrations of sodium. 2. Diets containing 1.6, 5, 10 or 15 g/kg dietary sodium were fed ad libitum to 1140 laying hens for a 12-week feeding period. A sample of excreta was collected from each experimental unit each week and its moisture content determined. All eggs produced were classified as clean or dirty according to the European Community Egg Marketing Regulations. A sample of eggs were collected from each experimental unit on 4 separate occasions in the last 4 weeks of the feeding period and the total bacterial numbers on ostensibly clean egg shells were determined. 3. Increasing dietary sodium concentration gave linear (P<0.01) increases in excreta moisture. Each 100 g/kg increase in excreta moisture increased (P<0.001) dirty egg numbers by 0.52% of the total eggs produced. Increasing excreta moisture gave a linear increase (P<0.001) in the (log-transformed) numbers of microorganisms that contaminated ostensibly clean egg shells.     

Factors affecting the use of perches in cages by laying hens

1. Three experiments were carried out with ISA Brown laying hens housed in individual cages with softwood perches of rectangular cross section fitted across the width of each cage, to investigate factors affecting the tendency of hens to lay their eggs from the perches and to use perches at other times. These factors were perch width and angle and method of perch introduction. 2. In experiment 1 there were 4 treatments. Perches were 38 or 60 mm wide; half of each width were flat and half were fixed at 8 , parallel to the slope of the floor. In 2 similar trials (with 48 and 44 birds respectively, equally divided between treatments) birds were moved to experimental cages already fitted with perches. Birds with 38 mm, sloping perches laid less than one third of their eggs from the perch (31% and 9% in the two trials) while those with the other designs laid more than 80% from the perch. Narrow sloping perches were not otherwise aversive and there was no consistent variation between treatments in total time perching. 3. In experiment 2, 32 birds were allowed to start laying on the floor of the experimental cages then perches were introduced at 24 weeks with 8 birds on each of 4 treatments: 50 mm perches fixed flat and 38 mm perches fixed flat, and at 5 and 10 respectively. Only 27% of eggs were laid from the perches with no variation between treatments either in this behaviour or in total time perching. 4. Experiment 3 provided 24 of the birds from experiment 2 with double-length perches to determine whether they showed preferences for the design features under consideration. Either half the perch length was flat and half sloping at 10 or half was 38 and half 50 mm wide. Again a relatively low proportion of eggs was laid from the perches (18%) and birds showed no significant preference for different perch designs as indicated by either how much they perched or where they perched. 5. These results suggest that both perch design and the way pullets are introduced to perches influence the proportion of perch-laid eggs. They confirm that in some circumstances laying from perches can be a serious problem, but that in other circumstances incidence can be reduced to a manageable frequency. Perches may therefore be practical in commercial production without increasing the number of cracked eggs. The results are also likely to be applicable in cages with other facilities including nest boxes.     

Studies on effects of nutritional factors on bone structure and osteoporosis in laying hens

1. A modern hybrid strain of laying hen (Hisex) was fed from point of lay to 68 weeks on a control diet and diets containing oystershell, fluoride, 1,25‐dihydroxycholecalciferol, ascorbic acid, a lower concentration of phosphorus and a combination of a lower concentration of crude protein and higher concentration of vitamin K. Hens from a much older strain (Brown Leghorn J‐line) were fed on the control diet.

2. Plasma variables were measured during lay. End‐of‐lay trabecular and medullary bone volumes in the proximal tarsometatarsus and free thoracic vertebra were measured by histomorphometry.

3. The majority of Hisex hens were considered to be osteoporotic by the end of lay. In contrast, none of the J‐line were osteoporotic.

4. None of the nutritional treatments affected trabecular bone volumes. Medullary bone volumes were increased significantly by feeding oystershell or fluoride.

5. There was no phenotypic correlation between egg production and trabecular bone volume in the Hisex hens.

6. The experiment provided evidence that osteoporosis in laying hens, as assessed by trabecular bone volumes, is not caused by calcium deficiency and could not be prevented by any of the nutritional treatments studied.     

Effect of low-temperature drying on the nitrogenous compounds and inositol phosphates in broiler chickens and cecectomized laying hen excreta

We investigated how the chemical composition of broiler chicken and cecectomized laying hen excreta is affected by drying in a forced-air drying chamber at low temperatures. Excreta that was immediately frozen after voiding provided the reference values. The excreta were dried in drying chambers for 4 hr, 6 hr, and 12 hr at 23°C or 33°C in the broiler experiment and 19°C or 29°C in the cecectomized laying hen experiment. The total N and inositol phosphate concentrations in the excreta of broiler chickens and cecectomized laying hens were not influenced (p > .050), except for one inositol tetrakisphosphate isomer (p = .026) in broilers. Compared to fresh excreta, drying did not affect the ammonia concentrations in the cecectomized laying hen experiment (p > .050), but the ammonia concentration was lower when dried for 12 hr at 33°C in the broiler experiment (p = .002). Amino acid concentrations in cecectomized laying hen excreta decreased until 4 hr of drying and then increased at both drying temperatures (p < .001). The results indicate that the applicability of drying poultry excreta at low temperatures in forced-air drying chambers to determine the chemical compound concentrations is trait-dependent. Future studies are necessary to investigate whether these results are also dependent upon the amount of excreta stored in the drying chambers.     

Lead concentrations in the blood and eggs of backyard laying hens

AIMS: To investigate the prevalence of lead exposure in hens and eggs from backyard poultry in a sample of Auckland households, the relationship between concentrations of lead in the blood of the hens and in the shells and yolks of eggs from the same household, and to examine associations with measures of hen health, environment and husbandry factors.

METHODS: Thirty households participated in the study from August to November 2016, each providing one adult hen for sampling, an egg from the household if available, and completing a questionnaire on hen husbandry. Concentrations of lead in blood were determined using a portable lead analyser. Eggs were analysed for concentrations of lead in the yolk and shell using inductively coupled plasma mass spectrometry after biological digestion with a mixture of nitric and hydrochloric acid.

RESULTS: Twenty three of 30 hens (77%) showed evidence of lead exposure, with median concentrations of lead in blood of 0.77 (min?<0.16, max 8.02) μmol/L. All eggs showed evidence of lead exposure, with concentrations of lead in the yolk ranging from 0.003–1.07?mg/kg, and concentrations of lead in the eggshell ranging from <0.1–0.82?mg/kg. A positive correlation existed between concentrations of lead in the blood of a hen and concentrations of lead in egg yolk from the same hen (R²=0.97), and both the yolk (R²=0.58) and shell (R²=0.30) of an egg from her flock. No association was found between concentrations of lead in blood and hen health indices measured in this study. Concentrations of lead in blood were higher in hens from properties with homes built before 1941 than between 1941–1960 (p=0.03), and in hens from properties with weatherboard homes than brick homes (p=0.049).

CONCLUSIONS AND CLINICAL RELEVANCE: There was a high prevalence of lead exposure in this sample of Auckland backyard chickens, with the majority of hens being sub-clinically affected. Associations were found between concentrations of lead in the blood of the hens, and properties with homes built before 1941 and clad in weatherboard. Concentrations of lead in over half the egg yolks sampled were at levels sufficient to warrant human health concern. The assessment of concentrations of lead in backyard poultry and eggs intended for human consumption is recommended to protect human and bird health.     

Selection for efficiency of food utilisation in laying hens: Causal factors for variation in residual food consumption

1. Lines selected for high and low values of percentage residual food consumption (PRFC) were compared.

2. Several traits were recorded in order to determine the nature of variation in PRFC: heat production, body temperature, plumage condition, size of comb, wattle and shank, digestibility, abdominal fat content, yolk size and egg quality traits.

3. The difference in adjusted heat production between high and low PRFC groups increased during selection and in the last generation was 120 kj/metabolic body size. Half of the observed difference was attributable to differences in activity. It was found that proportion of yolk, abdominal fat content, total featherless areas and plumage condition made significant but small contributions to the variation in PRFC.     

Effect of asymmetrical lighting on the body weight and carcase composition of laying hens and their influence on the efficiency of food utilisation

The body weight, carcase composition and component energy concentrations of laying hens were determined under 17L:7D and 2L:4D:8L:10D lighting regimens.

2. Hens subjected to 2L:4D:8L:10D lighting had lower body weights at end of lay and during most of the laying year, than the 17L:7D control birds.

3. Intermittently illuminated hens had similar absolute water, crude protein and ash contents to, but more water on a proportional basis than, controls.

4. Hens subjected to the 2L:4D:8L:10D lighting regimen had significantly less fat, in both absolute and proportional terms, than the controls.

5. There were no significant differences between the energy concentrations of the fat or fat‐free components of the two lighting groups.

6. There was no significant difference in the regression of fat content on body weight at end of lay for the intermittently and conventionally‐illuminated birds.

7. A prediction of the difference in daily energy requirement, based on egg output, body weight and mean daily body weight gain, very closely matched the actual difference in energy intake. This suggested that the more efficient food utilisation of intermittently‐illuminated hens could be explained by the lower body weight gain of these birds.     

The effects of low dietary concentrations of saponin on liver lipid accumulation and performance in laying hens

1. Feeding 4 or 5 g saponin/kg diet depressed food consumption, egg and body weights and liver lipid concentrations. Rate of egg production decreased initially but later returned to normal.

2. At 1 g/kg diet saponin had no effect on food consumption or laying performance but decreased the high liver lipid concentration in two experiments on a heavy (Warren) strain of bird. There was no effect on liver lipid concentration in another experiment using a light (White Leghorn) strain in which liver lipid concentration was low.

3. Excreta lipid, liver cholesterol and plasma high density lipoprotein‐cholesterol concentrations were unaffected by saponin but plasma tri‐glyceride concentrations were decreased.     

Tissue concentrations of sulphaquinoxaline administered in the food of laying hens

1. Sulphaquinoxaline (SQ) was fed to laying hens at a dietary level of 400 mg/kg for 3 successive days. SQ contents (mg/kg) in the blood, kidney, liver, ovary, muscle (thigh) and adipose tissue collected on 1, 2, and 3 d after the start of feeding were determined by HPLC. The relationship between the SQ content in the tissues and times (d) of SQ feeding was analyzed statistically. 2. Dietary SQ was distributed throughout the whole body. 3. Contents in tissues, except the kidney, had already reached a plateau by day 1 after the start of administration whereas in the kidney it increased linearly throughout the 3 days. 4. The plateau values of SQ in the tissues were much greater than those of sulphamonomethoxine and sulphadimethoxine.     

Effect of excess dietary sodium, potassium, calcium and phosphorus on excreta moisture of laying hens

1. Four experiments were conducted to investigate the effects of dietary concentrations of sodium, potassium, calcium or phosphate on the water intake and excreta moisture of laying hens. A fifth experiment examined the effect on these variables of increasing amounts of 2 different sodium salts (chloride or bicarbonate) and the interactions with 2 levels of dietary phosphorus. 2. All experiments involved individually caged laying hens fed on diets varying in 1 or 2 minerals in replacement for washed sand. The experimental diets contained mineral concentrations that either met or exceeded the expected requirement of the hens. The diets were given for a 7 or 8 d feeding period and food and water intakes were measured and excreta were collected for the last 48 h of each feeding period. These data were corrected for evaporative water loss to the environment during the collection period. 3. Increasing dietary concentrations of sodium, potassium or phosphorus gave linear increases (P<0.001) in the water intake of the laying hens and linear increases (P<0.01) in the moisture content of their excreta. Each 1 g/kg increase in dietary mineral increased the moisture content of the excreta by 9.04 (+/- 1.57), 11.95 (+/- 2.02) and 5.59 (+/- 0.31) g/kg (+/- standard error) for sodium, potassium and phosphorus, respectively. Increasing concentrations of dietary calcium did not significantly affect the water intakes or excreta moisture levels of the laying hens. 4. The fifth experiment showed that, although there was a sodium x phosphorus interaction (P<0.05), the effects of the 2 mineral additions were approximately additive. There were no significant differences (P>0.05) in water intakes or excreta moisture contents due to the 2 different sodium salts (chloride or bicarbonate).     

产蛋鸡胆固酵代谢及其影响因素

本文综述了产蛋鸡体内胆固醇的吸收、合成、转运、去路以及影响鸡蛋中胆固醇含量的主要因素.     

Effects of multiple environmental and nutritional factors in laying hens

1. A large experiment on multiple factors and levels of those factors was carried out to test the hypothesis that in production experiments responses can be measured separately and then applied as if interactions are rare.

2. Significant interactions of any order were indeed found to be rare, except for the interaction between temperature and dietary protein content.

3. Responses to temperature, light intensity, protein content and feeding system were reasonably consistent with earlier reports.

4. The rarity of interactions validates the use of a previously‐published additive model.     

Space and density effects on group size preferences in laying hens

1. T‐maze preference tests were used to study group size and space preferences in laying hens kept on deep litter. The first experiment revealed a non‐significant tendency to prefer a larger group (120 hens) in a large space (9 m²) over a smaller group (5 hens) in a small space (1 m³), but when the space was constant and large, a strong preference for the smaller group in a large space emerged.

2. In experiment 2, 5 different group size/space options were tested using a T‐maze and test hens were non‐randomly selected, choosing more aggressive ‘peckers’ and more subordinate ‘receivers’. Chi‐squared tests showed preferences for (1) a larger group (70 over 4 or 0 hens), (2) a larger space (9 m² over 1 m²) and (3) 4 hens rather than an empty space. Although both peckers and receivers preferred the same size companion hen groups, receivers were more consistent in their choice than peckers.

3. The results have important implications for hens in all group sizes and suggest that while smaller group sizes may be important, they need to be combined with sufficient space. Furthermore, the ‘ideal group size’ may differ depending on the individual hen's dominance status.     

Influence of graded levels of calcium and vitamin K in the diets of laying hens during the growing phase and their effects on the laying phase

The aim of this study was to evaluate the effect of dietary supplementation of vitamin K (vit K) and Ca in the diets of laying hens on bone and blood parameters and performance during the growing phase and the effects on the laying phase up to 32 weeks. The study utilized 120 Hy‐Line W‐36 pullets in the growing phase (13–18 weeks), 80 laying hens in the production phase (20–32 weeks), distributed in a completely randomized design in a 2 × 5 factorial arrangement, two levels of Ca (0.8 and 1.4%) and five levels of vit K supplementation (0, 2, 8, 16 and 32 mg/kg) with four experimental units. An experimental diet was fed during the growing phase, and the commercial diet was fed during the production phase and were analysed for biochemistry and bone variables at 18 and 32 weeks. In pullets, a significant interaction of levels of vit K and Ca was observed for total serum calcium (mg/dl), Seedor index, Ca in the bones (%) and medullary bone (%). Pullets at 18 weeks of age, receiving diets with 1.4% Ca, displayed a quadratic effect of vit K with better results for these variables with 17.86, 14.59, 14.48 and 16.80 mg/kg of vit K, respectively. For level 0.8% Ca no effect of vit K was observed. The treatments during the growing phase had no effect on egg production, performance and biochemistry serum until 32 weeks. Medullary bone (%), there was a significant interaction for 1.4% Ca and a quadratic effect for vit K, with greater medullary bone areas observed with 6.09 mg/kg vit K in the diet. Supplementation with vit K in a diet with 1.4% Ca during the growing phase allowed for an increase in the area of medullary bone at 18 weeks, which was maintained until 32 weeks.     

Sulphur amino acid requirement of laying hens and the effects of excess dietary methionine on laying performance

1. Individually‐caged laying hens were fed on maize‐soya bean meal diets containing 11.50 or 12.35 MJ ME/kg with sulphur amino acid (SAA) contents varying from 5.0 to 7.0 g/kg in period 1 (0 to 20 weeks); from 5.0 to 8.0 g/kg in period 2 (21 to 36 weeks) and from 5.0 to 10.0 g/kg in period 3 (37 to 52 weeks).

2. A SAA requirement of about 750 mg/hen d, of which about 425 mg was methionine, was found to be adequate for birds producing on average 51 g egg mass per hen d over 52 weeks. The SAA requirement was found to be higher for maximum efficiency of food utilisation than for maximum egg yield.

3. A diet containing 140 g protein/kg adequately supplemented with methionine and lysine, could sustain laying performance almost identical to that achieved on a diet containing 167 g protein/kg.

4. In diets with 140 g protein/kg the addition of 0.5 to 3.5 g dl‐methionine/kg diet in excess of the requirement did not affect egg production adversely, but food conversion efficiency was decreased.     

蛋鸡产蛋期蛋白质需要量的研究及数学模型的应用

针对产蛋鸡蛋白质和氨基酸需要量的研究现状及相关数学模型的应用作一综述。     

Plasma dispositions and concentrations of ivermectin in eggs following treatment of laying hens

AIMS: To determine the plasma disposition and concentrations of ivermectin (IVM) in eggs produced by laying hens following S/C, oral and I/V administration.

METHODS: Twenty-four laying hens, aged 37 weeks and weighing 1.73 (SD 0.12) kg were allocated to three groups of eight birds. The injectable formulation of IVM was administered either orally, S/C, or I/V, at a dose of 0.2?mg/kg liveweight, following dilution (1:5, v/v) with propylene glycol. Heparinised blood samples were collected at various times between 0.25 hours and 20 days after drug administration. Eggs produced by hens were also collected daily throughout the study period. Samples of plasma and homogenised egg were analysed using HPLC.

RESULTS: Maximum concentrations of IVM in plasma and mean residence time of IVM were lower after oral (10.2 (SD 7.2) ng/mL and 0.38 (SD 0.14) days, respectively) than after S/C (82.9 (SD 12.4) ng/mL and 1.05 (SD 0.24) days, respectively) administration (p<0.01). The time to maximum concentration and elimination half-life were shorter following oral (0.14 (SD 0.04) and 0.23 (SD 0.11) days, respectively) than S/C (0.25 (SD 0.00) and 1.45 (SD 0.45) days, respectively) administration (p<0.01). IVM was first detected in eggs 2 days after treatment in all groups and was detected until 8 days after oral and I/V administration, and until 15 days after S/C administration. Peak concentrations of IVM were 15.7, 23.3 and 1.9?µg/kg, observed 2, 5 and 4 days after I/V, S/C and oral administration, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE: The low plasma bioavailability of IVM observed after oral administration in laying hens could result in lower efficacy or subtherapeutic plasma concentrations, which may promote the development of parasitic drug resistance. Due to high IVM residues in eggs compared to the maximum residue limits for other food-producing animal species, a withdrawal period should be necessary for eggs after IVM treatment in laying hens.     

Interrelationships between dietary concentrations of sodium,potassium and chloride in laying hens

1. Twelve diets, representing the factorial combination of two concentrations of Cl‐ (0.8 and 1.4 g/kg), three concentrations of Na+ (0.5, 1.1 and 1.7 g/kg) and two concentrations of K+ (7 and 12 g/kg) were fed to groups of laying hens for 24 weeks and records taken of their productivity.

2. Different concentrations of Na+, K+ and Cl‐ showed highly significant interactions which were always similar. Thus, a deficiency of Na+ (0.5 g Na/kg) was aggravated by the restriction of Cl‐ (0.8 g/kg), but was partly compensated for by supplementing the diet with K+ (12 instead of 7 g/kg). Without a sodium deficiency other interactions occurred; for example, the higher concentration of K+ became unfavourable if the other two ions were also supplied at the higher concentrations.

3. These results show that, for the laying hen, the optimum concentrations of Na+, K+ and Cl‐ cannot be determined independently but depend upon the concentration of the two others in the diet.