Effects of maternal energy and protein intakes on the incidence of malformations and malpositions of the embryo and time of death during incubation

1. Broiler parent stock were fed daily allowances of 1.88, 1.73 or 1.52 MJ apparent metabolisable energy (AME) per bird at two different daily protein intakes (27.0 and 21.3 g crude protein (CP) per bird from 21 to 64 weeks of age.

2. The decrease in hatchability that occurred on the high protein (27.0 g CP), low energy (1.52 MJ AME) allowance from 26 to 36 weeks of age was due to an increase in the percentage of dead embryos in the second week of incubation and an increase in the number of “pipped” eggs at the end of incubation.

3. The low hatchability of eggs from birds on the 1.88 MJ AME allowance from 37 to 64 weeks could be related to the incidence of deaths in the first 5 d of the incubation period.

4. Malformations and malpositions of the embryo were not affected by maternal energy or protein allowance.     

Effects of different lighting regimes on diurnal feeding patterns of the domestic fowl

1. Male hybrid chicks were, from hatching, subjected to either a 12‐h photoperiod with uniform light intensity or a 12‐h photoperiod with a simulated “dawn” and “dusk” or to continuous light.

2. At 10 weeks of age the birds exposed to “dawn” and “dusk” were significantly heavier than those exposed to 12 h uniform illumination and these were heavier than those in continuous light.

3. From 15 to 25 weeks of age the birds in continuous light showed a marked diurnal rhythm in food intake, eating most in the period corresponding to normal daytime, while all birds subjected to 12‐h photo‐periods ate most at the end of the day, apparently having learnt to anticipate when their day would end.

4. When the birds subjected to continuous light were given one of the two 12‐h photoperiods, those given 12 h of uniform light intensity started by eating most food in the mornings, but later ate more towards the end of the day, while those with the “dawn” and “dusk”, ate more food at the end of the day during most of the 20‐d experimental period.

5. It is concluded that the birds preferred to eat most at the end of the day, probably to ensure adequate stores of food in the crop during the night. However, it was necessary for them to learn when their day would end, and this they did much sooner with the presence of a “dusk” than without it.

6. It is suggested that the difference in growth rate among the three treatments can be accounted for by differences in the efficiency of food conversion and also by differences in food intake.     

Effect of diet and natural variations in climates on the performance of laying hens

1. Laying hens raised in 3 natural tropical environments were fed on 2 series of diets with a view to defining the optimum combination of climate and dietary energy.

2. A combination of 3 growing climates, 3 laying climates (temperate, hot dry, hot humid), and 2 dietary energy concentrations (10.03 and 11.70 MJ ME/kg with protein concentrations proportional to energy) were tested for 46 weeks using 432 point‐of‐lay pullets.

3. Both growing and laying climates significantly affected most traits measured during the laying period. The patterns of egg production showed good persistency in all environments and differences observed reduced with age.

4. The difference between the high and low energy intake reduced at high ambient temperatures. Feeding low energy diets did not affect mean age at first egg, rate of lay or the egg output in the hot dry environment, nor egg weight in either hot dry or hot humid climates. Rather, feeding low energy diets resulted in improved body weight change in all 3 laying environments.

5. The growing climate and diet interacted significandy on body weight change, while highly significant interactions between laying climate and diet occurred on rate of lay, food and energy intake and egg weight during the laying period.     

The response of male broiler chickens to diets with various protein and energy contents during the growing phase

1. In two trials each using 2 400 male broilers, the regression of body weight on the linear effects of dietary protein, energy and age, the quadratic effect of age, and their interactions, accounted for approximately 99% of the observed variation during the growing and finishing period (3 to 8 weeks of age). Increasing either dietary protein or energy content significantly increased body weight.

2. The regression of food consumption on the linear effects of age, protein, energy and protein × energy interaction, and the quadratic effect of age accounted for 94% of the observed variation. The regression of food utilisation on the linear effects of protein, energy, and age and the quadratic effects of dietary protein and age accounted for 97% of the observed variation. Food consumption and efficiency were dependent on both dietary protein and energy, increasing with increases in either dietary protein or energy content.

3. The regression of fat in the dressed carcass on the linear effects of protein, energy and age accounted for 19% of the observed variation. Carcass fat increased with increasing age and dietary energy, and decreased with increasing dietary protein.

4. Although body weight, food consumption and utilisation were significantly different between trials, the proportion of carcass fat was not.     

Dietary rapeseed meal and the incidence of tainted eggs

1. Incorporating 0, 3, 6 or 9% rapeseed meal in the diet of brown‐egg laying birds for 28 d resulted in the production of 0, 1.2, 19.3 and 20.9% tainted eggs respectively, the first tainted eggs being laid on the fifth day.

2. During the second and third weeks the incidence of tainted eggs exceeded 20% but fell to 11.4% during the final week.

3. Omission of the rapeseed meal from the diets halted the production of tainted eggs.

4. Neither egg production nor the health of the birds was adversely affected by the treatments.

5. The taint was described as “ fishy ” or “ crabby ” and was distinctive, but the source was not identified.     

Effects of food intake regulation on the energy metabolism of laying hens

1. The effects of dietary energy restriction on the energy metabolism of post‐peak‐of‐lay hens of two hybrid layer strains were studied by indirect calorimetry.

2. Starving and resting rates of heat production (SHP and RHP) were measured, over 1‐d periods, at intervals during a 25‐week period in which the experimental birds were individually restricted to 80% of their previous energy intake ad libitum.

3. In both strains mean RHP per bird was about 7% lower in the restricted birds than in controls fed ad libitum, but when RHP was expressed in terms of metabolic body size (kg^0.75) the two groups did not differ.

4. Mean SHP per bird was about 18% lower in the restricted birds of both strains than in the corresponding controls; the decrease in SHP per kg^0.75 was 12%.

5. Heat increment of feeding and calculated maintenance energy were higher, and net availability of metabolisable energy for maintenance and production was lower, in the restricted than in the control groups.

6. Gross efficiencies of egg production, in terms of both mass and energy, increased in the restricted birds.

7. Live‐weight and total carcass energy after 25 weeks of restriction were respectively about 15% and 30% lower in the restricted groups of both strains than in the groups fed ad libitum.     

Fat deposition and heat production as responses to surplus dietary energy in fowls given a wide range of metabolisable energy: Protein ratios

1. Female broiler fowl between 21 and 42 d of age were given diets with apparent metabolisable energy (AME) contents ranging from 8 to 15 MJ/kg at each of two crude protein (nitrogen x 6.25; CP) contents (130 and 210 g/kg).

2. Food intake was measured daily for 21 d. Body composition was determined at 42 d and gains in body mass, protein, fat and gross energy calculated by comparison with a group analysed at 21 d. Heat production was calculated by difference between AME intake and energy gain.

3. Decrease of food mass intake with increased dietary AME concentration limited the increase in AME intake to about 25%, despite the near 2‐fold range of AME concentrations.

4. There was no effect of CP concentration on food mass intake. CP intake was directly related to CP: AME ratio.

5. When body weight differences were taken into account, heat production was independent of dietary AME concentration, but increased by about 8% on the higher‐protein diets.

6. There were strong linear correlations between dietary CP:AME ratio and carcase protein: energy ratio, carcase fat content and carcase protein content.

7. It was concluded that the growing fowl responded to dietary nutrient: energy ratio, and the associated differences in nutrient and energy intakes, by varying the rate of energy deposition as fat, without regulatory variation of energy dissipation as heat.     

Response of three class‐IV major histocompatability complex haplotypes to Eimeria acervulina in meat‐type chickens

1. The importance of MHC genes and background genes in controlling disease resistance, including resistance to avian coccidiosis, has not been clarified in meat‐type chickens.

2. The role of class IV MHC genes in resistance to Eimeria acervulina was assessed in F2 progeny of a cross between 2 meat‐type lines, selected divergently for immune response to Escherichia coli.

3. Disease susceptibility was assessed by lesion score, body weight, packed cell volume and carotene absorption.

4. Chickens with the “K” class IV MHC haplotype had lower lesion scores than chickens with “F” and “A” haplotypes.

5. Plasma carotene concentrations were higher in chickens with “K” haplotype and lower in chickens with “F” and “A” haplotypes whereas body weight and packed cell volume were less sensitive measures of Eimeria infection.

6. Eimeria acervulina resistance appears to be associated with MHC class IV genes; information about MHC haplotypes may be useful in selecting for increased resistance of meat‐type chickens to coccidiosis.     

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.     

Egg production of light and medium hybrids given diets varying in energy level during the chick,rearing and laying stages

A total of 1000 birds, one‐half of which were light and the other half medium hybrids, were given diets containing either high or low levels of metabolisable energy ad libitum during the chick (0.6 weeks), rearing (6–16 weeks), early laying (first 8 months) and late laying (last 4 months) stages.

The medium hybrids ate more and were heavier than the lighter hybrids at all stages. More eggs were laid by the light than by the medium hybrids but the latter laid larger eggs so that the total weight of eggs laid did not differ significantly between the two groups.

Medium hybrids given a low‐energy chick diet laid more eggs subsequently than those given a high‐energy chick diet, while the opposite result was obtained for the light hybrids.

Birds given a low‐energy rearing diet were lighter at 16 weeks and subsequently laid more eggs than birds reared on a high‐energy diet.

During the first part of the laying period consumption of the low‐energy diet was greater than that of the high‐energy diet, but the level and efficiency of egg production were the same for both dietary treatments. Mortality during lay was not significantly affected by dietary treatment or breed.     

Estimation of the relative bioavailability of copper sources in chicks fed on conventional dietary amounts

1. Tissue accumulation of Cu from dietary additions of 0, 5, 10, or 20 mg/kg Cu as reagent grade Cu acetate and feed grade Cu carbonate was determined in day‐old chicks fed on conventional maize‐soyabean meal starter diets (5.41 mg/kg Cu as‐fed basis) for 3 weeks.

2. Average daily food intake, daily weight gain and food conversion were similar among treatments.

3. There were linear increases in plasma and liver Cu concentrations (P< 0.01) as dietary Cu increased.

4. Bioavailability of Cu as carbonate was 0.66 that of Cu in the acetate based on the multiple regression slope ratio of liver Cu concentration on added dietary Cu. Although responses for the two Cu sources did not differ significantly, the relative bioavailability of the Cu carbonate was similar (0.66 vs 0.68) to that obtained in an earlier study (Ledoux et al., 1991) with greater dietary Cu contents (150, 300 and 450 mg/kg) in which the slopes of the equations representing the two sources differed (P<0.05).     

Influence of activity and dietary energy on broiler performance,carcase yield and sensory quality

1. A total of 2560 male and female Ross broilers were raised to 42 days of age in a 2 × 2 treatment factorial arrangement experiment to investigate the influence of different degrees of physical activity and dietary energy on broiler performance, abdominal fat content, carcase yield and sensory quality.

2. Vertical fans were used to force the treatment birds to walk 3 to 4 times as far as the normal activity birds; birds were fed a normal and a high energy diet (12.55 compared with 13.81 MJ ME/kg) with the same energy/protein, energy/lysine and energy/methionine + cystine ratios.

3. High activity birds had greater body weight ( + 4.1%), food intake ( + 5.1%) and ME intake ( + 5.1%) than normal activity birds. Birds receiving high energy diet had a lower food conversion and food intake than birds receiving normal energy diet. There were no significant differences in body weight or ME intake between birds with different diets.

4. Slaughter yields, both absolute and relative to live body weight, were affected by activity or dietary energy to varying degrees. Breast meat was increased with more activity. The absolute weight of abdominal fat was independent of activity and in males the relative weight of abdominal fat was decreased in high activity birds.

5. Different degrees of activity and dietary energy had only minor influences on broilers' sensory quality.     

Comparison of the effects of dietary supplementation of flavonoids on laying hen performance,egg quality and egg nutrient profile

1. The aim of this experiment was to compare the effects of dietary supplementation of hesperidin, naringin and quercetin on laying hen performance, egg quality and egg yolk lipid and protein profiles.

2. A total of 96 Lohmann White laying hens weighing an average of 1500 g at 28 weeks of age were randomly assigned to a basal diet and the basal diet supplemented (0.5 g/kg) with either hesperidin, naringin or quercetin. Each treatment was replicated in 6 cages in an 8-week experimental period. Data were analysed using one-way analysis of variance.

3. None of the dietary flavonoids affected laying performance and eggshell quality. Hesperidin and quercetin supplementations decreased albumen and yolk indexes.

4. As compared to the control group, egg yolk cholesterol content decreased and egg yolk protein content increased in response to dietary hesperidin and quercetin supplementation. The mean egg yolk cholesterol (mg/g) and protein (g/100 g) contents were 10.08/14.28, 16.12/14.08, 14.75/15.04 and 15.15/14.85 for the control group and groups supplemented with naringin, hesperidin and quercetin, respectively.

5. Egg yolk lipid and protein profiles were variable.

6. In conclusion, dietary supplementation of hesperidin or quercetin could be used in the diets during the early laying period to reduce egg yolk cholesterol and increase egg yolk protein, which may be attractive to consumers.     

Effect of dietary energy concentration on the response of laying hens to amino acids

1. A hypothesis, that the optimum amino acid concentration in the diet is not directly proportional to the dietary energy concentration, but changes in inverse proportion to the change in food intake resulting from a change in energy concentration, was tested in three experiments.

2. Response experiments involving the amino acids methionine, lysine and isoleucine were conducted, in each case at three dietary energy concentrations, using a diet dilution and blending technique, thereby ensuring a constant ratio between background amino acids and the first‐limiting amino acid in all diets, and also keeping the ratio of amino acids to energy constant as energy varied.

3. A common response curve relating egg output (g/bird d) to amino acid intake (mg/bird d) for each amino acid, fitted by means of the Reading Model, adequately described the response at each of the dietary energy contents. This implies that energy does not influence egg output directly, but only indirectly through its effect on food intake and hence on amino acid intake.

4. Both amino acid and energy concentration significantly influenced food intake. Energy intake was not constant over all dietary energy concentrations, being lower at low energy levels and higher at high energy concentrations.

5. It is concluded that amino acid requirements should not be stated either as percentages or as ratios with energy. Optimum amino acid intakes and energy concentrations should be calculated; the expected food intake should then be predicted, after which the appropriate concentration of nutrients in the diet can be determined.     

Effects of high inclusion rates of salseed meal in the diet of chicks

1. Starter diets containing either maize or salseed meal to replace the maize were fed to chicks over a period of 2 weeks.

2. Growth rate, food intake, food utilisation and proportion of dietary nitrogen retained were much poorer in chicks receiving salseed meal.

3. The chicks receiving salseed meal developed pathological lesions in liver and kidney.

4. The red blood cell count, white blood cell count, haemoglobin concentration and packed cell volume of the chicks receiving salseed meal were lower than those of chicks receiving maize.

5. The apparent metabolisable energy value of salseed meal was determined as 6.83 MJ/kg.     

Effects of battery gage shape and dietary energy regulation on the performance of laying hens offered diets containing dried poultry manure

1. About 3000 medium‐weight hybrid chicks were used in a factorial experiment involving two “chick” treatments: diets containing 0 and 50 g dried poultry manure (DPM)/kg; three “grower” treatments, diets with and without 50 g DPM/kg given ad libitum and regulated amounts of the diet with DPM; five “layer” treatments: diets with 0, 100 or 200 g DPM/kg given ad libitum and regulated amounts of diets containing 110 and 220 g DPM/kg and two shapes of layer cages: deep (conventional) and shallow.

2. Chick diets had no significant effects on rearing or subsequent laying performance.

3. Food‐regulated pullets were 7% lighter than pullets given the DPM diet ad libitum at 18 weeks but consumed 12.5% less food; growing treatments had no significant effect on subsequent egg production.

4. Hens housed in shallow cages laid 10.3 eggs/bird‐housed more than those in deep cages, produced 3.8% greater egg mass, consumed 2.7% less food and produced fewer damaged (cracked, broken and hair‐cracked) eggs (P< 0.001).

5. DPM‐containing layer diets had no adverse effects on egg production, or mortality; with 100 g DPM/kg efficiency of food conversion (EFC) was better than with 0 or 200 g/kg (P< 0.001).

6. Reduction of the energy intake of L110R and L220R hens with diets containing 110 and 220 g DPM/kg by 8.2 and 9.0% respectively, reduced the number of eggs laid/hen‐housed by 6 and 10.7 but improved the EFG (P< 0.001); there was no significant interaction between cage shape and energy regulation.     

The effect of heat treatment and enzyme supplementation on the nutritive value of barley for broiler chicks

1. The effect of heat treatment and enzyme supplementation on the nutritive value of barley was studied.

2. In only one experiment was weight gain significantly improved when the barley was heated.

3. Autoclaving barley at 120 °C for 30 min reduced dietary dry matter digestibility and treating the barley with dilute acid before heating had no effect on its nutritive value.

4. Supplementing diets containing commercial barley with a‐amylase produced slightly conflicting results in that there was an improved weight gain, food conversion efficiency and digestibility value in two of three experiments.

5. The digestibility and metabolisable energy values of a North American six‐row spring barley (Glacier) were significantly improved by enzyme supplementation.

6. The effect of the enzyme on diets containing a high amylose barley (Glacier Pentlandfield) was positive but not significant.     

Effects of energy and protein allowances during lay on the reproductive performance of broiler breeder hens

1. Broiler parent stock were fed daily allowances of 1.88, 1.73 or 1.52 MJ apparent metabolisable energy (AME) per bird at two different daily protein intakes (27, 21.3 g crude protein (CP) per bird) or daily protein intakes of 24.6 and 19.4 g CP per bird at a daily energy intake of 1.88 MJ AME per bird from 21 to 64 weeks of age.

2. Body‐weight gain and carcass fat and water content increased and fertility decreased with increasing energy allowance. Maximum egg production occurred at an energy intake of 1.73 MJ AME/bird d.

3. Differences in egg weight and hatchability were related to differences in both energy and protein intake. The highest egg weight occurred at the highest allowance of energy and protein. Hatchability was depressed where the daily allowances of protein and energy were in a ratio of more than 15 g protein: 1 MJ AME.

4. Apart from egg size no significant effects on reproductive performance were observed when dietary protein intake was varied from 27 to 19.5 g/bird d.

5. Requirements of broiler breeder hens for protein during lay may be lower than previously thought. For the strain used a protein intake of 19.5 g/bird d appeared adequate provided essential amino acid concentrations were maintained.

6. The close relationships between body weight and energy allowance and the latter and egg production make body‐weight gain a useful guide to management. A body‐weight gain of about 1.1 kg from 21 to 36 weeks of age was associated with optimum performance in this study.     

Influence of ascorbic acid on the adverse effect of feeding a diet containing excess tyrosine to chicks

1. The effects of dietary or parenteral administration of ascorbic acid on the adverse effects of excess dietary tyrosine were investigated with young male White Leghorn chicks in a 2‐week experiment.

2. Addition of 10 g ascorbic acid/kg to the control diet (without excess tyrosine) produced no beneficial effects on performance. Excess dietary tyrosine caused depressions in all measures of performance.

3. Adding 0.1, 1, 10 or 20 g ascorbic acid/kg to the diet containing excess tyrosine tended to improve performance.

4. Subcutaneous injection of 50 mg ascorbic acid/bird d to chicks receiving excess tyrosine brought about a significant improvement in body‐weight gain.

5. The elevation of plasma free tyrosine caused by excess dietary tyrosine decreased as dietary ascorbic acid increased.

6. Ascorbic acid can alleviate, though not completely counteract, the adverse effect of excess dietary tyrosine.     

Effect of added soyabean oil and dietary energy on metabolisable and net energy of broiler diets

1. The ‘extra caloric’ effect of added soyabean oil, as reflected in improved body weight gain, food utilisation, metabolisable energy or net energy deposition in the body was determined.

2. Two diets were formulated to contain 12.1 MJ/kg, one with no added fat and the second with 30 g/kg soyabean oil. Addition of oil improved body weight gain by 6.9% (P< 0.05). Two other diets were formulated to contain 13.0 MJ/kg, one with 30 and one with 60 g/kg added soyabean oil bringing the total fat in the high energy, high fat diet to 84 g/kg. Addition of oil in this case improved weight gain by only 3^.4% (ns). Addition of soyabean oil increased the apparent digestibility of total dietary fat and reduced that of starch.

3. The effect of soyabean oil supplementation on mash diets at both energy concentrations or to the pelleted diet (formulated to contain 12.1MJ) on AME_n was consistently positive although not significant. Addition of soyabean oil improved net energy deposition in the body by 17% within the 12.1 MJ/kg diets, (30 g/kg soyabean oil addition) (P< 0.05), but was reduced by 2% (ns) within the 13.0 MJ/kg diets (60 g/kg soyabean oil addition).

4. Supplementing a pelleted diet formulated to contain 12.1 MJ/kg, with 30 g/kg soyabean oil, improved food utilisation (P< 0.05). The ‘extra caloric’ effect of added soyabean oil, defined as the beneficial effect of the oil above that predicted from its energy value, varied according to the parameter chosen to express this effect and was influenced by the concentration of added soyabean oil and the dietary energy.