Temporal patterns of ovulation,oviposition and feeding of laying hens under skeleton photoperiods

1. The ovulation, oviposition and eating pattern of laying hens showed that the second light period in the 2L:12D:2L:8D skeleton photo‐period is interpreted as the start of the subjective day.

2. This interpretation is independent of the light period during which the animals are serviced.

3. During each of the 2L periods about one‐third of the total food is eaten, the other third is eaten during the 8D period: little or nothing is eaten during the 12D period.     

Restricting energy intake of laying hens: Effects of different patterns of restriction and rehabilitation

1. Light hybrids were subjected to ten treatments, consisting of different timing, length and severity of energy restriction alternating with periods of unrestricted feeding, between 24 and 68 weeks of age.

2. The pattern of restriction had no direct effect but affected egg production indirectly through its influence on overall energy intake.

3. Groups fed ad libitum throughout laid more and heavier eggs than any restricted group.

4. A decrease in daily egg output of about 4 g was associated with each 100 kJ reduction in daily metabolisable energy intake.     

Diurnal and oviposition-related changes in heart rate, body temperature and locomotor activity of laying hens

Diurnal and oviposition patterns of heart rate (HR), deep body temperature (BT) and locomotor activity (LA) in conscious and unrestrained Rhode Island Red hens were studied by a radiotelemetry system. Behavioral observations were also made on diurnal changes and during the pre‐ and post‐laying period. Heart rate, BT and LA showed characteristic diurnal changes synchronized with a photoperiod of 15 h light and 9 h dark. In the light period, HR, BT, and LA levels were significantly higher than in the dark period (P < 0.001). Furthermore, the highest levels of these parameters were recorded just after they were fed (08.30 hours), while the lowest level was measured after lights‐off and remained stable throughout the dark period. Behavioral observations indicated that during the light period the hens spent most of their time in very active movement, exhibiting various behavioral patterns. However, in the dark period the hens spent almost all their time resting. The present results suggest that performing various behavioral activities cause heat generated by muscle exertion, which plays a significant role in daily HR, BT, and LA in laying hens. However, during the 60 min before and after oviposition, LA appeared to have increased steadily toward the moment of laying, and then regressed gradually in the post‐laying period to a level significantly lower than in the pre‐laying period (P < 0.001). Furthermore, the pre‐laying behavior of hens indicated extreme restlessness and more activity, whereas the post‐laying period is characterized by less activity and increased relaxation. Consequently, laying behavior has a profound but transitory effect on HR and BT, suggesting that oviposition was probably associated with intense LA.     

The effect of feeding hemp seed meal to laying hens

Seed of the hemp cultivar Unika-b was cold-pressed to obtain hemp seed meal (HSM) containing 307 g/kg crude protein and 164 g/kg ether extract (60 g/kg linoleic acid, 120 g/kg alpha-linolenic acid, 160 g/kg oleic acid, lesser amounts of palmitic, stearic, and gamma-linolenic acids). For 4 weeks, 102 43-week-old DeKalb Sigma hens were fed on isonitrogenous and isoenergetic diets containing 0, 50, 100 or 200 g/kg HSM. Eggs were collected for fatty acid analysis during the fourth week of feeding these diets. No significant differences were found between feed treatments for egg production, feed consumption, feed efficiency, body weight change or egg quality. Increasing dietary inclusion of HSM produced eggs with lower concentrations of palmitic acid and higher concentrations of linoleic and alpha-linolenic acids.     

Diurnal variation in heat production related to some physical activities in laying hens

1. Heat production, standing and eating activities, and hourly food intake of 4 laying hens were observed simultaneously and the effects of activity and food intake on heat production were studied. 2. Average heat production during the dark period (20.00 to 06.00 h) was 18.9 kJ/kgW0.75 h which was 33% lower than that during the light period. About 76% of the light-dark difference in the rate of heat production was probably associated with activity and posture. 3. Standing time, which included a range of behavioural activities, occupied 90% of the light period and the increased rate of heat production associated with standing was estimated to be about 18% of daily heat production. 4. Eating time occupied 40% of the light period; the heat production associated with eating activity represented about 5% of daily heat production or 3% of ME intake. 5. Because the regression of heat production on time spent eating agreed with the regression of heat production on hourly food intake, it is suggested that the energy expenditure associated with ad libitum feeding can be estimated for hens from the regression of heat production on hourly food intake.     

Effects of dietary boron supplementation on laying hens

1. The effects of dietary boron on egg production and on the ultimate shear force, stress, and fracture energy of the tibia, femur, humerus, and radius from White Leghorn laying hens were investigated.

2. The shear force, stress, and fracture energy of the bones were not affected by increasing dietary concentrations of boron.

3. Egg production, food consumption and body weight were suppressed at a dietary boron concentration of 400 mg/kg.

4. Boron concentrations increased significantly in all tissue samples tested in birds given 400 mg/kg dietary boron.     

Stress and feather pecking in laying hens in relation to housing conditions

1. Possible association between high rates of feather pecking and increased stress were investigated in laying hens. 2. From week 19 to week 30 after hatching, 16 groups of 11 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without long-cut straw as foraging material and provided with food in the form of pellets or mash. 3. Stress was assessed by egg production, weight gain, tonic immobility (TI), heterophil/lymphocyte (H/L) ratio and antibody titres to sheep red blood cells (SRBC), tetanus toxoid (TT) and human serum albumin (HSA). 4. Provision of foraging material and food form influenced feather pecking. Rates of feather pecking were highest in groups housed without straw and fed on pellets. 5. Egg production was reduced in pens without straw but not affected by food form. Both the duration of TI and H/L ratios were influenced by provision of foraging material and food form. TI was longer and H/L ratios were increased in hens housed without straw and in those fed on pellets. Antibody titers to SRBC and TT were lower in pens without straw than with straw but not influenced by food form. 6. In conclusion, foraging material and food form affected both feather pecking and indicators of stress, suggesting that feather pecking in laying hens is associated with stress.     

The intermittent feeding of anti-bacterial and-or antifungal agents to laying hens

A study was conducted in order to ascertain the effects of feeding large doses of various antibacterial (chlortetracycline, furazolidone, bacitracin) and/or anti‐fungal (nystatin, cupric sulphate) agents to laying hens on an intermittent basis. None of the drugs tested enhanced the performance of the birds when fed singly. However, birds that received a diet intermittently containing a broad‐spectrum antibiotic (110 mg/kg of diet) exhibited a performance superior to that of the control group when the antibacterial treatment was immediately followed by the feeding of a ration containing 55 mg nystatin/kg, during the 7 subsequent days.

It is possible that the intermittent, successive feeding of massive amounts of antibacterial and antifungal agents may act synergistically to promote egg production and efficiency of food utilisation. An economic evaluation of the data revealed that, at constant egg production levels, the feeding of chlortetracycline‐supplemented diet (110 mg/kg of diet) for 3 consecutive days, immediately followed by feeding a nystatin supplement (55 mg/kg of diet) for 7 consecutive days, the cycle being repeated every 4 weeks, led to a larger net profit than the feeding of chlortetracycline‐supplemented or unsupplemented diets.     

Restricted feeding time and the behaviour of caged laying hens

1. Layers housed as pairs in cages were denied access to food from 07.30 to 15.30 h each day. Analyses of video records of daily activity patterns showed several behaviour changes compared with the patterns shown by similar birds allowed ad libitum (AL) access to food. 2. Birds given restricted access (RA) to food spent more time sitting and cage pecking while unable to feed than those feeding ad libitum during the same period. They also engaged in less agonistic pecking and the lengths of bouts of drinking were reduced during the period of food denial compared with the AL treatment. 3. After the food troughs were uncovered birds on the RA treatment showed fewer bouts of feather pecking but more bouts of drinking than the AL treatment. 4. Improvements previously reported in the efficiency of food utilisation of birds on the RA treatment may have been the result of additional sitting, although other activities requiring energy expenditure were performed. 5. It is concluded that restricting access to food on a time basis has both positive and negative effects on the welfare of caged layers.     

The daily food consumption of laying hens in relation to egg formation

The voluntary food consumption of, respectively, 4 and 5 colostomised laying hens was studied in 2 experiments at both normal (20° C.) and high (30° C.) environmental temperatures over a total period of 60 days. Food consumption was greater during 24 hr periods when egg formation was in progress than when no egg was present in the oviduct. At high temperatures food intake was reduced less on egg‐forming than on non‐egg‐forming days.

In a further experiment lasting 24 days 12 normal pullets laying for long sequences with pauses of single days consumed 25 per cent more food in the 19 hr period 14.30–09.30 hr when eggs were being formed than when they were not. During the 5 hr period 09.30–14.30 hr food consumption was significantly greater when albumen was being secreted than when shell formation was in progress.

It is suggested that the requirements of the bird for albumen synthesis may regulate food intake during the period of egg formation.     

Alleviation of hysteria in laying hens with dietary tryptophan.

A commercial layer breeder flock that was suffering from hysteria was fed a diet containing 5 grams tryptophan/kg for six days. The incidence of episodes of hysteria declined from five times/hour on day 0 to once/hour on day 6 and none on day 8. Feed consumption increased from 107 g to 145 g/hen/day and egg production increased 23% during the six day feeding period. The tryptophan concentration in plasma doubled (from 95.6 to 188.2 mumol/mL). Plasma phenylalanine and tyrosine also increased. Birds that were not in lay, by postmortem examination, had significantly higher plasma valine concentrations (476.4 vs 372.7 mumol/mL). Tryptophan, serotonin and related metabolites increased in both the hypothalamic region and the remainder of the brain following tryptophan feeding, and subsequently declined. High levels of dietary tryptophan may be useful in alleviating hysteria in poultry.     

Relationships between fear of humans, productivity and cage position of laying hens

1. The productivity and behavioural responses of laying hens to humans were examined in relation to the effects of tier, row and position of the cage along the row over three consecutive 4-week periods. 2. Birds from the top tier had lower hen-day production, lower egg mass output and poorer efficiency of food utilisation than birds from the bottom tier in the third period. 3. Birds from the top tier showed greater avoidance of an approaching experimenter when in their cage or when on a table. 4. The production variables were significantly correlated with a number of behavioural responses to humans and a novel object, and with the corticosteroid response to handling/blood sampling. 5. The data suggest that birds from the top tier were more fearful of humans and that this higher level of fear may have been responsible for their lower productivity.     

Influence of dietary osteolathyrogenson the eggshell quality of laying hens

1. Laying hens were fed osteolathyrogens, either semicarbazide hydrochloride at 0.3 or 0.4 g/kg or β-aminopropionitrile fumarate at 0.5 or 0.6 g/kg diet to examine their effects on eggshell quality. 2. Shell quality characteristics considered for evaluation were shell surface area, shell thickness, shell weight, percentage shell, shape index and the specific gravity of eggs. Measurement of shell quality traits revealed that the hens fed osteolathyrogens laid eggs with significantly lower specific gravities and proportion of shell by weight. These differences were not explained by differences in shell thickness or weight or the shape index of eggs. 3. It was concluded that osteolathyrogens cause hens to lay eggs with poor shell quality and such eggs are weak and fragile.     

Effect of dietary fibre on the performance of laying hens

1. In tests to determine whether gizzard weight could be influenced by dietary fibre concentrations, caged layers were fed on diets containing 15, 30 or 60 g pine shavings/kg diet.

2. As dietary fibre content increased, gizzard weight increased, but there was no effect on body weight, hen‐day production, egg weight, efficiency of food conversion, mortality, percentage of liver ether extract or egg shell breaking strength. Percentage of body ether extract tended to be lower when pine shavings were fed.     

大葱叶粉饲喂产蛋鸡的应用研究

大葱芳香、辛温。是人们日常生活中广泛食用的蔬菜及调味品．但人们主要食用葱的茎和少量叶。大部分葱叶被弃掉．尤其是在入冬前冬葱贮藏时，废弃的大葱叶数量是相当可观的。而且大葱叶富含生物活性物质和多种维生素．饲料中添加一定量的大葱叶，可以改善饲料的适口性．增加畜禽的采食量．促进消化吸收，加速畜禽生长．还可以起到消炎、杀菌、驱虫等防病保健作用。为此．我们课题组将大葱叶添加于产蛋鸡生产中进行研究．取得了初步可喜的成果。具有研究和开发价值。现将大蒜叶加工后的大蒜叶粉饲喂产蛋鸡的试验研究报告如下：     

Effect of feeding clinoptilolite (zeolite) to three strains of laying hens

1. One hundred and twenty 16-week-old, single combed pullets of three strains were fed on a diet containing 160 g protein/kg with or without 50 g clinoptilolite/kg in a trial with 20 hens per treatment. Sterile river sand replaced clinoptilolite in the control diet in order to keep the diets isonergetic. 2. The hens were individually caged in a naturally-ventilated laying house and fed on one of the two diets for ten 28-d periods. 3. No significant dietary effects between treatments were observed with respect to body weight, age at first egg, egg weight, Haugh scores or food intake/hen. 4. Significant dietary effects in favour of clinoptilolite feeding were noticed with the number of eggs laid per hen, shell thickness, efficiency of food utilisation, droppings moisture content and mortality. 5. Significant differences between strains were observed with respect to all measurements taken except food intake/hen d.     

Effects of moderate energy restriction on light and medium hybrid laying hens

1. Two light and two medium hybrid strains were fed, from 32 to 48 and from 56 to 68 weeks of age, ad libitum or approximately 89%, 85% and 80% of the ad libitum intake; from 48 to 56 weeks all the birds were fed ad libitum.

2. A daily energy restriction of 11 to 13% in the first period, resulted in the rate of lay being depressed by nearly 11% points for one light hybrid strain and by more than 5% points for the medium hybrids while the corresponding depressions in egg weight were 4% and 2%.

3. During rehabilitation egg output was similar for controls and restriction treatments, though that of the most severely restricted groups remained slightly depressed.

4. Energy restriction of about 8% during the second period depressed rate of lay by about 3% points and egg weight by about 2%.     

Influence of dietary calcium and phosphorus on metabolism and production in laying hens

1. The effects of different dietary concentrations of calcium (24 to 56.9 g/kg) and phosphorus (4.5 to 14.2 g/kg) on production and some aspects of metabolism were studied in laying hens.

2. Treatments did not affect egg numbers, food consumption, conversion efficiency of food to egg, bodyweight gain or mortality.

3. Increasing dietary calcium (Ca) significantly increased plasma Ca and inorganic phosphorus (P), breaking strength at the radius and egg specific gravity and significantly decreased plasma alkaline phosphatase and egg weight.

4. Increasing dietary phosphorus increased plasma P and decreased egg specific gravity significantly.

5. Plasma Ca, P and alkaline phosphatase and radius breaking strength were suitable indices of the Ca status of the hens.     

Changes in feather condition in relation to feather pecking and aggressive behaviour in laying hens

The aim of this experiment was to describe and examine the relationship between pecks received by individual birds and the feather and skin damage of those birds at different ages. The effect of group size was also studied. Laying hens were raised in floor pens in group sizes of 15, 30, 60 and 120 birds, each with 4 replicates. Behavioural observations were performed at the ages of 22, 27, 32 and 37 weeks. Detailed feather scoring was carried out at the ages of 18, 23, 28 and 33 weeks. Behavioural observations focused on the number of feather pecks (gentle and severe) and aggressive pecks received, and on the part of the body that was pecked. Scoring of feather and skin damage focused on the same 11 parts of the body. Increasing numbers of aggressive pecks received were associated with decreased body weight and increased feather damage at the ages of 27 and 32 weeks. The number of severe feather pecks received was significantly related with feather damage at all ages; however, no relation with gentle feather pecks received was found. Group size had a significant effect on feather condition, with large group sizes having most feather damage.     

The absorption and excretion of minerals by laying hens in relation to egg shell formation

The absorption and urinary and faecal excretion of calcium, phosphorus, magnesium, sodium, potassium and chloride were studied in four colostomised laying hens during 24 hr periods. The urinary excretion of ammonia was also determined. Data for 10 laying and 5 non‐laying days were obtained. On laying days (a) net absorption of all minerals, expressed either as actual weights or as a percentage of intake was greater, (b) urinary excretion of phosphorus, potassium and ammonia was greater and of calcium, magnesium and chloride less and (c) retention of all minerals was greater, than on non‐laying days.

The urinary findings can be largely explained in terms of the requirements of the shell gland for calcium and bicarbonate ions and the need to excrete the phosphate liberated from the skeleton during egg shell formation.