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.     

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.     

Sudies on low metabolisable energy wheats for poultry using conventional and rapid assay procedures and the effects of processing

1. A significant proportion of wheat cultivars grown in New South Wales had low apparent metabolisable energy (AME) values (< 13.0 MJ/kg dry matter) for growing broilers when determined by the conventional total collection technique.

2. The low AME was due to a reduced starch digestibility and was not improved by grinding the wheat finely or by steam pelleting the diet.

3. Higher AME values were obtained when determinations were made with adult cockerels than with growing broilers when the conventional technique was used.

4. AME values determined using a rapid bioassay technique (Farrell, 1978) with growing broilers or adult cockerels were considerably higher than values determined using the conventional procedure with growing broilers.

5. Inter‐laboratory studies showed that the true metabolisable energy (TME) assay gave reproducible values for individual and blended wheat samples, but that these values were higher than AME values determined by the conventional procedure. Similar TME values were found with growing broilers and adult cockerels.     

A comparison of methods for estimating the metabolisable energy of a sample of grass meal

1. The inclusion of grass meal in the diets of broilers and laying hens reduced food intake and, as a consequence, the apparent metabolisable energy (AME) and nitrogen‐corrected AME (AME_N) values estimated for the grass meal were artificially low.

2. With young broilers the AME and AME_N values of a sample of grass meal were estimated to be 5.97 ± 0.45 and 6.05 + 0.46 MJ/kg dry matter respectively.

3. With adult laying hens the AME and AME_N values of the sample of grass meal were estimated to be 5.36 ± 1.04 and 6.26 ± 0.96 MJ/kg dry matter respectively and the corresponding true metabolisable energy (TME) and nitrogen‐corrected TME (TME_N) values were shown to be 9.12 ± 1.25 and 8.66 ± 1.33 MJ/kg dry matter.

4. It was further illustrated that if the dietary intake of the adult birds had been 100 g/d, the AME value of the grass meal would have been estimated as 8.33 MJ/kg dry matter.     

Protein and energy metabolism in two lines of chickens selected for growth on high or low protein diets

1. Genetic adaptation was investigated in broilers selected for seven generations on a normal (A) or a low (B) protein diet.

2. Protein and energy metabolism were studied in males from these selected lines fed on a diet of intermediate protein content.

3. All selected birds retained more nitrogen than those studied 10 years previously.

4. There was no difference in nitrogen retention between groups, although relative growth rate of group B birds was higher.

5. Heat productions relative to gross energy intake were 0.38 (group B) and 045 (group A). Energy retentions relative to gross energy intake were 0.39 (group B) and 0.35 (group A); the difference being primarily due to higher fat retention in group B.

6. Using a common maintenance requirement for metabolisable energy, group B utilised metabolisable energy for growth (0.78) better than did group A (0.71).

7. At 53 d of age plasma glucose (10%) and insulin (50%) were higher in group B than in group A.     

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.     

Diet selection by Japanese quail (Coturnix coturnix japonica) in relation to ambient temperature and metabolic rate

1. A choice between a high‐energy, wheat‐based, low protein mixture and a lower‐energy, soya‐based, high protein mixture was offered to growing Japanese quail at ambient temperatures of 20°, 25°, 30° and 35°C.

2. The quail were kept in open‐circuit respiration calorimeters, so that diet selection could be related to energy requirement.

3. Increasing ambient temperature had no significant effect on food intake by weight, but the proportion of the high energy choice decreased and, conversely, the proportion of the lower‐energy but higher‐protein choice increased.

4. Energy intake was therefore negatively correlated with ambient temperature, but protein intake per unit of energy intake increased, allowing the birds to gain weight at about the same rate at all temperatures.

5. Heat production decreased as ambient temperature increased. Respiratory quotient decreased with increasing temperature, which indicates a reduced utilisation of carbohydrate as an energy source.

6. Water intake increased with temperature but there were no overt signs of heat stress and there was no significant change in body temperature.

7. Japanese quail selected a dietary mixture which maintained similar growth rates over a wide range of ambient temperature, by sustaining protein intake but altering energy intake in line with thermoregulatory energy demands.     

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.     

A comparison of the energy and nitrogen metabolism of broilers selected for increased growth rate,food consumption and conversion of food to gain

1. Calorimetric measurements were made on 5‐week‐old male chickens sampled from the third generation of three lines selected for either increased live‐weight gain (W), food consumption (F), or food conversion efficiency (E). A control line (C) was also measured.

2. Food intake and food conversion ratio were greater (P<0.05) in the F line than in the E and C lines.

3. Metabolisability of the diet was 0.8% higher in the E line than in the other lines.

4. Metabolisable energy (ME) intake and heat production were greater (P<0.05) in the F line than in the E and C lines, and energy balance was greater (P<0.05) in the F than in the W and E lines.

5. During starvation, excreta energy and heat production were greater (P < 0.05) in the F than the other lines.

6. Availability of ME (net energy) was the same (85%) for all lines but calculated daily maintenance energy requirements (kJ ME/kgW) were W, 860; F, 937; E, 796 and C, 810.

7. By 9 weeks the F line contained more fat and less water than lines E and C.     

Lysine requirement of broiler chicks as affected by protein source and method of statistical evaluation 1

1. An experiment was designed to test if the lysine requirement, expressed as g lysine/kg CP, was the same for several protein sources.

2. Groundnut meal, groundnut meal adjusted with indispensable amino acids or sesame meal supplied the dietary CP at 180 g/kg diet. Increments of lysine (1.5 g/kg diet) were added to each of these diets.

3. The gain, food intake and food efficiency responses of broiler chicks were analysed using a quadratic equation and a two‐slope method. An estimate of lysine requirements was also obtained from a survey of college students.

4. The different methods produced widely different estimates of lysine requirement.

5. The average lysine requirement was estimated at 50.1 g lysine/kg CP for groundnut meal, 61.7 for adjusted groundnut meal and 54.9 for sesame meal.

6. Reasons for the effect of statistical analysis and protein source on lysine requirement are discussed.     

Effect of dietary energy restriction on retention of protein,fat and energy in broiler chickens

1. Broiler chickens were fed 60–100% of recommended energy intakes to study the effects of energy restriction on protein and fat retention.

2. At an energy retention of 179 kJ/kg W ^0·75 d, only protein was retained. At higher energy intakes, each increment in retention had a rather constant composition: about 85% energy in fat and 15% in protein. At lower energy intakes body fat was mobilised whereas protein was deposited.

3. The efficiencies of energy retention in protein and fat were estimated to be 0·66 and 0·86 respectively.

4. The rather constant composition of additional retained energy after additional energy supply provides an explanation for a linear relationship between energy intake and energy retention.     

The effects of age,dietary fat and bile salts,and feeding rate on apparent and true metabolisable energy values in chickens

1. Apparent (AME) and true (TME) metabolisable energy values of four diets, containing 50 or 150 g animal fat or maize oil/kg, were estimated in young and adult chickens. The diets were given with and without a supplement of 5 g bile salts/kg. Three feeding rates, ad libitum, and l/6th or 1/3rd of ad libitum were compared.

2. In younger birds, endogenous energy losses were higher when measured in starved birds than when estimated by regression analysis.

3. In young birds, feeding rate had no effect on AME of diets containing 50 g lipids/kg but it significantly affected TME. These results were reversed in adults. AME and TME values of diets containing 150 g lipids/kg were affected by the feeding rate in both young and adult birds.

4. Bile salts increased metabolisable energy values of diets containing high concentrations of saturated fatty acids and their effect was more pronounced in young birds.     

Relationship between digesta transit time and apparent metabolisable energy value of wheat in chickens

1.?This study tested the hypotheses that: (a) apparent metabolisable energy (AME) values and whole tract transit time (WTTT) were related, and that (b) the relationship between AME and WTTT differed between male and female Ross broiler chickens.

2.?Enzyme products with xylanase activity were added to a basal diet to provide 4 dietary treatments comprising control (no enzyme), Avizyme 1300 (1 kg/tonne), Kemzyme W1 (1 kg/tonne), and Bio-Feed Wheat CT (200 g/tonne). The basal diet comprised (in g/kg), 800 wheat, 155 casein, 20 dicalcium phosphate, 11 limestone, 7 D,L-methionine, 2 vitamin and mineral premix, 3 sodium chloride and 2 choline chloride (60%).

3.?AME values for diets were determined in a 7-d energy balance study commencing when chickens were 21 d of age. WTTT was the time elapsed (in min), from time of administration by oral gavage of 200 mg ferric oxide in a gelatine capsule, to time of first observation of the distinctive red colouration in droppings.

4.?The mean AME value for the wheat was high (15·7 MJ/kg dry matter) and ranged from 14·4 to 16·3 MJ/kg dry matter for individual birds. Mean WTTT was 206 min and ranged from 105 to 429 min. AME and WTTT were unaffected by enzyme addition to the diet, and the interaction between diet and gender was not significant.

5.?There was a significant but weak positive relationship between AME and whole tract transit time, with AME increasing by 2·2 kJ/min. This relationship was unaffected by gender of the chicken.     

Artificial light sources and their influence on physical activity and energy expenditure of laying hens

1. The influence of fluorescent and incandescent artificial lighting in a 16L:8D day/night schedule on number and intensity of movements, and on total, resting and activity‐related energy expenditure was investigated.

2. Fluorescent light showed the same positive correlation between light intensity and physical activity at all activity levels as was found previously for incandescent light.

3. Light‐dependent physical activity under fluorescent light was higher than under incandescent light at illuminances of 5 lux and above, indicating the fowl's ability to perceive qualitative light differences.

4. Total and activity‐related energy expenditure were positively associated with illuminance; resting energy expenditure was not influenced.

5. Total, resting and activity‐related energy expenditure were not statistically significantly different between light sources.

6. The results are discussed in relationship to Teichmuller's concept of adequate lighting and the characteristics of the fowl's visual system.     

Metabolic and anatomical adaptations of light‐bodied chicks to intermittent feeding

1. Chicks of a light‐bodied strain were deprived of food on alternate days from 15 to 46 d of age.

2. Hyperphagia, amounting to twice the intake of control birds early in the experiment, occurred on the repletion day.

3. Final body weight attained 80% of that of the controls.

4. Body fat concentration decreased at first but returned to that of controls after 3 weeks.

5. A consistent hyperlipaemia was observed after food deprivation or restoration.

6. There was a marked increase in the digestive enzymes found in the small intestine, but not in the pancreas during the repletion day.

7. These responses may be considered as mechanisms to reduce the physiological manifestations of starvation.     

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.     

A comparison of the energy and nitrogen metabolism of fed ducklings and chickens

1. Energy measurements were made over 4 d on groups of three ducklings (aged from 5 to 22 d), and three broiler chickens (aged from 11 to 32 d) offered high‐ or low‐energy diets.

2. Food, metabolisable energy (ME) and water intakes were significantly higher for ducklings than for chickens. The ratio of water : food was 4.2 : 1 and 2.3 : 1 for ducklings and chickens, respectively. The food conversion ratio differed between diets but not species. Performance was generally better for both species on the high‐energy diet.

3. Heat production, energy, fat and protein retentions were higher for ducklings than chickens, and ducklings retained 0.44 of their energy as fat compared with 0.37 for chickens. Overall the ratio of protein (g) to fat (g) retention was 2.2 : 1 and 2.8 : 1 for ducklings and chickens respectively.

4. For ducklings, metabolisability of the high‐energy diet declined from 0.774 to 0.747, and to a lesser extent of the low‐energy diet, as they aged. There was no such decline for chickens. Net efficiency of utilisation of ME for gain was 0.64 for ducklings compared with 0.50 for chickens.

5. Fractional retention of dietary nitrogen (N) was 0.62 for ducklings and 0.55 for chickens. Gaseous ammonia‐N was 4.5 and 2.2%, respectively, of N retained.

6. In a second experiment groups of ducklings only, were offered high‐and low‐protein diets from 12 to 22 d of age. Comparisons among four diets showed that food and energy intake was lower on the low‐protein diet than on the other three. Energy retention on the high‐energy diet was greater (P<0.05) than on the other three diets.

7. It was concluded that a high‐energy diet is important for ducklings and chickens for maximum biological performance during the first 4 weeks of life.     

Calorimetric measurements of the energy and nitrogen metabolism of Japanese quail

1. Respiration calorimetry measurements were made over 4 d on normally‐fed groups of 10 male or 10 female quail during three periods commencing at 12, 19 and 26 d of age. Carcass compositions were determined on groups of birds of each sex at 2 and 5 weeks of age.

2. Expressed per unit body weight, food and metabolisable energy (ME) intake and weight gain decreased between 2 and 3 weeks of age, but remained constant thereafter.

3. No differences were observed between sexes for any variable measured. Efficiency of utilisation of ME for energy retention was only 0.33. This was mainly because the majority of energy was retained as protein tissue.

4. Nitrogen (N) retention (g/d) increased with increasing dietary N intake but when expressed as a proportion of N intake, declined from 0.46 at 2 weeks to 0.33 at 4 weeks. Fat retention increased substantially during week 4.

5. Carcass analyses showed that fat, protein and ash were higher for quail at 5 weeks than at 2 weeks of age. At 5 weeks carcass fat was only 60 g/kg.     

Effect of feeding diets based on coarse maize on productive performance,gizzard development and energy utilisation of laying hens

1. A total of 2200 White Leghorn layers were used to study the effect of feeding coarse maize on productive performance, gizzard weight, apparent metabolisable energy (AME) and egg quality parameters.

2. The experiment was a completely randomised design with 5 treatments, each being replicated 5 times (88 birds per replicate). Dietary treatments included a control diet with 600 g/kg of ground maize (6 mm sieve) and experimental diets with 150, 300, 450 or 600 g/kg coarse maize (10 mm sieve) replacing (w/w) ground maize. Diets, in mash form, were offered from 39 to 62 weeks of age.

3. Over the entire experimental period, dietary treatments had no effect on any of the production parameters, except on feed intake. A quadratic effect was observed for feed intake, where intake increased at 150 g/kg coarse maize inclusion. At higher inclusion levels of coarse maize, feed intake was similar to that of the control diet. But the differences in daily intake between dietary treatments were only around 1 g/bird and may not be of any biological significance.

4. Dietary treatments had no effect on gizzard weight, AME or egg quality.

5. The results indicate that coarse maize could completely replace maize in layer diets with no adverse effect on egg production, egg quality and dietary energy utilisation. In the current work, although the proportion of coarse particles (over 1 mm) increased with increasing inclusion levels of coarse maize, the differences in the percentage of particles above 1 mm between the fine control (0 g/kg coarse maize) and coarsest (600 g/kg coarse maize) diets was only 15%, and this may limit the value of the findings reported herein.     

Anti‐nutritive activity of wheat pentosans in broiler diets

1. To assess their possible anti‐nutritive activity wheat pentosans were isolated from a milling by‐product and added at graded levels to a sorghum‐based broiler chicken diet.

2. A water‐insoluble pentosan preparation (WIP, 720 g arabinoxy‐lan/kg) caused a depression of apparent metabolisable energy (AME) of 1.63 MJ/kg DM at the highest level of inclusion (41.9 g/kg). Broilers maintained on this diet showed significant growth depression and a decrease in feed conversion efficiency.

3. A water‐soluble pentosan preparation (WSP, 520 g arabinoxy‐lan/kg) showed less anti‐nutritive activity.

4. In a second experiment the AME of rice (pearled), maize, sorghum, wheat, triticale, barley and rye was determined. The AME values obtained were highly correlated (r= — 0.98, P<0.001) with the summed levels of pentosans and β‐glucans found in the cereals.

5. It was concluded that the pentosans of wheat possess anti‐nutritive activity when present in broiler diets and that similar polysaccharides may influence the nutritive value of other cereals.