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A cross-sectional[4pc] survey investigating husbandry and productivity of free-range village chickens was carried out in four administrative districts within 60 km of Accra. Responses were provided by 101 men and 99 women. The mean (SD) household flock size was 28.7 (25.97) and the median was 20. The factors included in the final model investigating variance in flock size were sex of the respondent (p = 0.011), administrative area (p = 0.004), the numbers of members in the household (p = 0.017) and the number of cattle, sheep and goats owned by the household (p = 0.031). Chickens were owned by individual members of the household, but women and children were the predominant providers of care for chickens. All respondents described their chickens as scavengers that were provided with supplementary feed, and over 80% of respondents named maize as a supplementary food source. Approximately 50% of respondents claimed difficulty in providing supplementary feed, with the degree of difficulty varying between administrative areas (p < 0.001). A majority of respondents (approximately 65%) claimed that their chickens laid 3-4 clutches of eggs per year. Over 70% of respondents estimated that each clutch contained 10-20 eggs, and approximately 70% of respondents estimated that 75% of the eggs hatched. Opinions on mortality varied, but 60% of men and 70% of women estimated that between 50% and 75% of both chicks and adult birds died each year. Approximately 80% of respondents named Newcastle disease as the most important health issue. The opportunities for and consequences of controlling Newcastle disease are discussed.

1. Two intermittent lighting systems for laying hens are: the Biomittent system, using an asymmetric pattern of 0.25L:0.75D for 16 h followed by 8D, which entrains oviposition to 24 h cycles and, compared with standard lighting programmes, gives the same egg number and egg size but a smaller feed cost, and a symmetrical system (4[3L:3D]) which allows intervals between ovipositions to stretch, giving bigger eggs with thicker shells, but yielding fewer eggs and achieving no saving in food intake. 2. A new system was devised to combine the increased egg size and shell thickness, characteristic of symmetrical intermittent lighting programmes, with the reduction in food intake which is a feature of programmes that reduce total activity time. The pattern tested was 24(0.25L:0.75D). 3. The results of 2 trials showed that this new system gives about 2% fewer eggs than conventional (Step Up) or Biomittent lighting with a 2% increase in mean egg size and a 3% improvement in shell thickness at the end of the laying year. Feed consumption with the new system was similar to that under Biomittent lighting and 6% lower than that recorded for Step Up lighting. 4. Mortality was lower with the new system than with Step Up lighting, but not significantly so. From the evidence of other trials it is argued that intermittent lighting programmes which provide less than 8 h total illumination in 24 h generally reduce laying house mortality and may be regarded as beneficial to the welfare of the hen.

1. Medium weight laying hens were used for an assay to determine their isoleucine requirement between 26 and 36 weeks of age and again between 46 and 56 weeks of age. 2. Two isoleucine-limiting mixtures were formulated with similar amino acid profiles, one containing 198 g and the other 110 g crude protein per kg diet. These mixtures were blended to give a series of 11 diets with isoleucine contents ranging from 7.6 to 3.8 g/kg. The lowest protein diet was also fed with a supplement of L-isoleucine. Each of the 12 diets was given to 5 groups of 24 laying hens. 3. The daily isoleucine requirement of individual laying hens was estimated to be 9.48 mg/g egg output plus 44.47 mg/kg body weight per day for the 1st period and 12.11 mg/g egg output plus 6.86 mg/kg body weight per day for the 2nd period. Calculated optimum intakes of isoleucine for various ratios of cost of input to value of output are tabulated. For example, for a flock of medium weight hens producing an average of 50 g daily egg mass, the optimum isoleucine intake (mg/hen d) varied between 760 and 890 varying for ratios of costs to egg prices. 4. It is concluded that the isoleucine required per day does not decrease during the first laying year despite a decrease in rate of egg output.

1. One experiment was conducted with medium weight laying hens to determine their threonine requirement between 28-38 weeks. 2. Two threonine-limiting diets of identical protein quality (summit-dilution) were used and, by dilution, ten protein contents were produced supplying 2.7 to 5.4 g total threonine/kg diet. The diet with the lowest protein was also supplemented with synthetic L-threonine. Each diet was fed to 5 groups of 24 laying hens. 3. The daily threonine requirement of the individual laying hens was estimated by direct methods to be 8.7 mg/g egg output plus 43.49 mg/kg body weight for this experiment. Calculated optimum intakes of threonine for various ratios of costs of input to value of output are tabulated. For example, for a flock of medium weight laying hens producing an average of 50 g daily egg mass, the optimum threonine intake (mg/hen d) varied between 700 and 710 for cost ratios (k-values) varying between 0.002 and 0.001.

The injection of endotoxin isolated from a pathogenic avian strain of Escherichia coli (1 mg/kg intravenously) accelerated the depletion of liver glycogen in fasting nine- to 10-week-old chickens within the first hour and concurrently reduced their plasma inorganic phosphate levels. These changes were attributed to increased glycogenolysis and were followed by hypoglycaemia and a large increase in the lactate content of the plasma which appeared to be caused by enhanced glucose oxidation and reduced gluconeogenesis. The plasma glucose level returned to normal within three hours and simultaneous changes in the plasma urate and albumin content indicated that glucose was being synthesised from amino acids and that albumin was being catabolised to provide them.

Fatty liver-haemorrhagic syndrome (FLHS) occurred in the controls and was modified in hens that received a diet containing 10 per cent rapeseed meal. This diet increased the extent and severity of the hepatic haemorrhage without affecting the reticulin content of the liver but decreased the body weight and liver lipid levels and so weakened the correlation between these parameters and haemorrhage score found in FLHS. Plasma aspartate transaminase and beta-glucuronidase activities tended to increase with the score. The rapeseed meal diet also produced thyroid hypertrophy and since this was greater in the hens that produced tainted eggs and was positively correlated with the trimethylamine (TMA) content of the eggs it was postulated that rapeseed meal goitrogens may be involved as secondary factors in producing the disturbance in TMA metabolism that causes the egg taint. This abnormality was associated with a reduction in the soluble protein content of the liver, which reflected a decrease in TMA oxidase activity, but was not related to hepatic haemorrhage, steatosis or reticulolysis, or to lipid levels and the activities of lysosomal enzymes and transaminases in the plasma.

The injection of chickens with Escherichia coli endotoxins immediately produced a 50 per cent rise in plasma caeruloplasmin activity which was attributed to the release of the protein from liver cell. This was followed by a fall in activity, which was probably due to a fall in activity, which was probably due to a stabilising effect of adrenocortical hormones on the cell membranes, and then by a five-fold increase. The results of experiments with cycloheximide, adrenocorticotrophin, beta-methasone and reserpine indicated that the third phase of the response reflected increased synthesis in the liver which was partly induced by adrenal hormones. It increased with the dose and was not elicited by the particulate nature of the toxin preparation or by its lipid and polysaccharide components.

1. Two experiments were conducted to provide further evidence about rate of lay under the Cornell lighting system (2L:4D:8L:10D). Each used 1728 hens of each of 2 brown-egg stocks in 12 light-proof rooms. 2. In the first the Cornell system was compared at 2 light intensities (average values 2 and 10 lux) with a conventional step up lighting programme. In the second, Cornell lighting was introduced at 18, 21 or 24 weeks of age and compared with a step up programme. 3. Total egg output was essentially the same from the Cornell lighting system, using 10 h light/d, as from the step up programme using 16 h/d. When the Cornell system was applied abruptly at 18 weeks to pullets which had been reared on short days (8L:16D) sexual maturity was advanced, resulting in an increase in mean rate of lay to 72 weeks of age and a reduction in mean egg size. Application of the Cornell system from 21 or 24 weeks gave the same egg numbers and the same egg size as the step up programme. 4. Food intake was about 2% lower with the Cornell treatment in both experiments. Although this difference was not quite significant in either, it probably reflects a real effect of the reduced hours of light. It represents a greater potential cost saving than the reduced electricity consumption. 5. Birds in rooms with an average light intensity of 2 lux laid slightly fewer eggs but their eggs were 0.5 g heavier than those laid in rooms maintained at 10 lux. There were no interactions between light intensity and light pattern or between stocks and light pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

A high energy maize diet produced a higher incidence of fatty liver-haemorrhagic syndrome than a low energy barley diet when the diets were fed during the summer. The triglyceride content of the liver increased with the liver haemorrhage score and in hens with the highest scores there was evidence of hepatic hyperplasia. They also had high activities of aspartate transaminase and cholinesterase in the plasma and a low activity of sorbitol dehydrogenase. There was no increase in plasma endotoxin levels as the syndrome developed or any significant variation in these levels with the haemorrhage score, the triglyceride content of the liver or plasma enzyme activities. It was concluded that the steatosis does not impair the ability of the liver to inactivate endotoxins of enteric bacteria and that these toxins are not involved in the pathogenesis of the syndrome.

Unidirectional air flow isolators were used to house laying hens at 13 degrees C, 18--30 degrees C and 29 degrees C. Their diet was formulated to provide 2655 k cal metabolisable energy/kg and 142 g crude protein/kg. Groups were killed for examination at the age of 35 and 45 weeks. Sub-clinical FLHS occurred in all isolators but in the case of the younger hens appeared to be more prevalent at 29 degrees C than at 13 degrees C. Both the triglyceride and the glycogen content of the liver were higher at 29 degrees C despite a reduction in food intake. The free fatty acid level in the plasma was lower, probably as a consequence of reduced lipolysis. Liver haemorrhage was associated with an increase in plasma aspartate transaminase activity. It was concluded that an interaction between environmental temperature and the energy balance is not the only factor involved in the aetiology of FLHS and maybe of secondary importance, and that there is a pathogenic relationship between hepatic steatosis and haemorrhage.

Groups of adults which were selected for low and high (normal) TMA oxidase activities produced chickens with a predominance of the same character showing that capacity for synthesizing the enzyme is strongly inherited. The low and high strains became homogenous in generations 2 and 3, respectively, demonstrating that the genetic factor that impairs the synthesis of TMA oxidase can be readily removed by selective breeding. There was a 7-fold difference in the hepatic TMA oxidase activities of the strains at the age of 1 day and a 26-fold difference at 22 days. The synthesis of the enzyme increased rapidly in the high strain between the ages of 8 and 36 days but did not alter significantly in the low strain. Sex had no effect on TMA oxidase synthesis. The high strain showed better feather development and laid eggs with paler shells. There was no difference in their growth rate, egg production or hatchability.

The intravenous injection of endotoxins isolated from Escherichia coli serogroups O111 and O78 (2 mg/kg) increased the activities of aspartate transaminase and lactate and sorbitol dehydrogenases in the plasma of six- to 11-week-old chickens during the next 24 h. These changes were compared with those produced by adrenocorticotrophic hormone and beta-methasone and were attributed to tissue damage involving the liver followed by increased enzyme synthesis which may have been induced partly by adrenocortical hormones. Further evidence of liver damage was provided by a fall in the activity of cholinesterase. The alkaline phosphatase activity gave no indication of cholestasis.

The intravenous injection of E coli endotoxin (serogroup 0111 : B4) into eight to nine week old disease-free fowls (0-025-3-0 mg/kg) produced successive falls in the plasma potassium and calcium levels during the 9 h following the injection. This change in the potassium concentration was accompanied by a slight rise in that of sodium, and in some cases a slight rise in that of sodium, and in some cases a slight reduction in the magnesium concentration was detected when that of calcium was reduced. No effect was observed 24 h after the injection. The metal-binding properties of endotoxin, its affinity for membranes and its effect on the secretion of adrenocortical hormones may be involved in the production of these responses. Their pathophysiological significance is also discussed.

A high incidence of subclinical fatty liver-haemorrhagic syndrome (FLHS) was found in three flocks of laying hens in which deaths from FLHS had occurred. There was so significant difference between the affected hens and the remainder of the block in egg production or quality, but the former were more obese and had higher concentrations of lipids in their livers, suggesting a pathogenic relationship between hepatic steatosis and haemorrhage. Soluble protein tended to accumulate with the fat in the livers. Reticulolysis had occurred in over half the haemorrhagic livers examined. Histological examination and DNA estimations provided no evidence of generalised hyperplasia. From the composition of the liver lipids it was concluded that the steatosis resulted mainly from an increase in lipogenesis from dietary carbohydrate. Lipid levels in the plasma were weakly correlated with those in the liver. No change was detected in the plasma protein pattern.

A syndrome resembling fatty liver-haemorrhagic syndrome in laying hens was reproduced in six- to seven-week-old chickens by injecting oestradiol-17beta-dipropionate intramuscularly (total dose 20-50 mg/kg). The degree of hepatic steatosis and the severity and extent of haemorrhage from the liver varied with the dose and the results suggested a pathogenic relationship between the two conditions. There was no evidence of reticulolysis in the liver. When food was withdrawn for 24 h after the last injection there was a dramatic fall in the haemorrhage score and a reduction in the lipid content of the liver.

Isocaloric diets supplying about 2900 kcal/kg and based on maize, wheat and barley respectively, were fed to pullets for 13 weeks from point of lay. The number of cases of subclinical fatty liver-haemorrhagic syndrome and the mean total lipid, triglyceride and monoglyceride content of the liver decreased in the above order of diets. The final body weight, weight gain and abdominal fat score followed the order wheat greater than maize greater than barley. Reduction of the energy content of the wheat and barley diets to 2670 and 2490 kcal/kg respectively by the omission of animal fat was associated with a reduction in the lipid content of the liver only in the case of the wheat diets. Egg production and quality were uniformly high and no difference was detected in plasma triglyceride and free fatty acid levels.

During the 2 h following the injection of chickens (aged nine to 11 weeks) with endotoxin isolated from a pathogenic strain of Escherichia coli (O78) there was a transient rise in the activity of acid phosphatase, aryl sulphatase and beta-glucuronidase in the plasma, suggesting increased release of these enzymes from lysosomes. This was followed by a fall in their activity which may have been due largely to stabilisation of the lysosomal membrane brought about by increased secretion of adrenocortical hormones and/or accelerated removal of the enzymes from circulation by the reticuloendothelial system.

The injection of four-to nine-week-old fowls with Escherichia coli O111:B4 endotoxin (0-1 and 1-0 mg/kg) produced a two to eight fold rise in the histaminase activity of the plasma 24 h afterwards. In some cases this increase was still detectable after 48 h. This activity was strongly correlated with the p-phenylenediamine oxidase activity of caeruloplasmin. Electrophoretic studies with 7-5 per cent polyacrylamide gels indicated that fowl caeruloplasmin also was histaminase and putrescinase activity and that the release of this protein from the liver by endotoxin is largely responsible for the increase in the activity of the plasma. In untreated fowls this activity was lower than published values for several mammals and does not explain the relative resistance of the fowl to the acute effects of endotoxins and large doses of histamine.

The injection of fasting nine- to 10-week-old chickens with endotoxin from a pathogenic avian strain of Escherichia coli (1 mg/kg iv) reduced the triglyceride, cholesterol and phospholipid content of the plasma 2 to 5 h afterwards. This effect was similar to that of an E coli infection and opposite to that produced in mammals. There was a transient rise in the cholesterol level within the first hour.

1. Two experiments are described in which a system of intermittent lighting (15 min light followed by 45 min dark for 15 h, then 15 min light, 30 min dark, 15 min light and 8 h dark) was applied to laying pullets from 37 to 72 weeks of age. A step-up lighting programme was used as a control treatment (8L:16D from 0 to 18 weeks, photoperiod increased by 20 min each week from 18 to 41 weeks, 16L:8D from 41 to 72 weeks of age). 2. Food consumption was reduced by about 5% when intermittent lighting was in use and by 3.8% for the period from 18 to 72 weeks. 3. Rate of lay and egg weight were similar for intermittent lighting and the control treatment, provided that protein content of the diet was adjusted to maintain an adequate amino acid intake. 4. In the second trial 2 stocks, 2 stocking densities confounded with 2 temperatures and 2 types of food trough were used. Each of these factors affected food intake and it was found that more food was saved by intermittent lighting when intake was high and less when it was low. The proportion saved was approximately 5%. 5. Mortality was slightly but not significantly lower in both experiments where intermittent lighting was used. This may indicate that caged pullets are under less stress when intermittent lighting is used.

Diets containing 500 g high-glucosinolate rapeseed meal/kg or an equivalent amount of soybean meal as the only protein supplement were fed to layer-type chickens and two broiler strains from 1 to 56 d of age. Additional groups of the former were maintained on the diets until they were 16 and 28 d old. The rapeseed meal produced thyroid hypertrophy in all strains but reduced the growth rate of only one of the broiler strains. The livers of chickens fed on rapeseed meal were enlarged and DNA analysis indicated hyperplasia, but no macroscopic lesions were found. The activities of aspartate transaminase, lactate dehydrogenase and alkaline phosphatase in the plasma were increased by rapeseed meal, suggesting liver damage. In all strains, feeding rapeseed meal increased plasma total protein, albumin and cholesterol and decreased urate. Hyperglycaemia accompanied by a decrease in plasma triglycerides occurred in the layer strain. Through its extra-thyroidal toxicity (-)5-vinyl-oxazolidine-2-thione (goitrin) was probably responsible for most of these changes.

During 24 h after the injection of fowls (aged eight to 11 weeks) with Escherichia coli endotoxin (1 to 3 mg/kg) isolated from a pathogenic strain (O78) there were changes in the ascorbate content of the adrenal gland and increases in the plasma free fatty acid levels, indicating that the toxin behaves as a mild stressor.

Amounts of 125I-labelled thyroxine (T4) and triiodothyronine (T3), representing approximately 50 per cent of the plasma concentration, were incubated with chicken plasma or serum, the proteins were separated by polyacrylamide gel electrophoresis at pH 7.4 and the distribution of the hormones determined. Seventy to 75 per cent of T4 migrated with albumin, about 10 per cent with the alpha-globulin and most of the remainder with a pre-albumin fraction. The percentage attached to the pre-albumin tended to increase with age. Neither barbiturate nor 8-anilino-1-naphthalene sulphonic acid (ANS) affected the distribution. About 50 per cent of T3 was associated with albumin, 30 to 40 per cent with the main alpha-globulin and most of the remainder with an adjacent globulin band. ANS reduced the percentage attached to albumin and increased that associated with the alpha-globulin. Barbiturate had no effect.

Rapeseed meal hepatosis was produced by feeding high and low glucosinolate meals as a source of protein (about 200 g kg-1 diet) but could not be distinguished histologically from fatty liver-haemorrhagic syndrome which occurred in birds on the control diet. Both types of meal increased haemorrhage, reticulolysis and lymphoproliferation in the liver, reduced the packed cell volume and caused thyroid enlargement. Haemorrhages emanated from ruptured intrahepatic portal veins, capillaries and sinusoids and were associated with degenerative changes in vessel walls. Haemorrhage and reticulin scores were correlated. Parenchymal necrosis occurred only around large haematomas and caused increased aspartate transaminase activity in the plasma. Both meals also caused hyperglycaemia and reduced the plasma triglyceride content. Only the high glucosinolate meal decreased egg production, caused liver enlargement and reduced the plasma urate level. The addition of myrosinase enhanced its effects on egg production and packed cell volume but did not increase its hepatotoxicity.