Comparison of food intake,rate of consumption,pecking activity and behaviour in layer and broiler breeder males

1. The food intake, rate of food consumption (g/min) and behavioural time budgets of individually caged broiler and layer (white egg) males were compared in the early morning (1.5 to 3.5 h after onset of photoperiod) and afternoon (5.5 to 7.5 h after photostimulation) on 4 different days at 11 to 12 weeks of age. Correlations among rate of consumption, the proportions of time on different activities and previously estimated scores for fearfulness were calculated.

2. Food intake and rate of consumption were two‐fold greater in broilers than in layers. The proportion of time spent feeding in the morning was lower in layers compared with broilers and was similar in the afternoon. Rate of consumption was higher in the morning than in the afternoon in both lines.

3. Overall, a similar proportion of time was spent feeding, standing and sitting in bodi lines. The birds were more likely to be sleeping (eyes closed) in the afternoon than in the morning.

4. The proportions of time spent on preening, pecking and stereotypic pacing were greater in layers than in broiler breeders. The proportion of time spent drinking tended to be higher in broiler breeders than layers.

5. Two measures of fearfulness, aversion to a looming human and a novel rod were respectively positively and negatively correlated to time drinking and stereotypic pacing.

6. The time spent in stereotypic pacing was negatively related to rate of consumption and time spent preening.

7. The results suggest that low food intake is associated with increased arousal, fear and frequent feeding and drinking. There was no evidence that beak related activity was related to fearfulness.     

Food intake and growth in chickens given food in the wet form with and without access to drinking water

1. Individually caged growing chickens were offered a commercial grower food mixed with 1–5 to 2^‐25 times the weight of water and the effects, compared to giving the same food in air‐dry form, on food intake, body weight gain and carcase composition were investigated.

2. Male broilers (24) were given either a grower food in the air‐dry form with access to drinking water or the same food mixed with 2–0 parts of water (700 g water/kg of mixed food) with no drinking water from 28 to 49 d of age. From 49 to 63 d all birds were given dry food and drinking water and were then killed for carcase analysis. Food intake and weight gain were significantly increased during the wet‐feeding period, as was carcase protein but not abdominal or carcase fat at the end of the experiment.

3. Five male broilers were given each of 5 dietary treatments containing 0 (control), 1.5, 1.75, 2.0 and 2.25 times added water (640, 673, 700 and 723 g water/kg) from 28 to 49 d. Food intakes, body weight gains and carcase weights were significantly increased for all water additions compared with dry food, but there were no significant differences between different water additions.

4. Female broiler chicks responded to wet feeding (700 g water/kg) in a similar manner to males and the dry matter approximate digestibility was increased from 0.65 for the dry food to 0.73 for the wet.

5. Cockerels of an egg‐laying strain did not increase their intake of dietary dry matter when it was fed in the wet form (700 g water/kg), but there was a significant increase in body weight gain.

6. Male broilers were offered wet food (700 g water/kg) with or without access to drinking water. There was equal stimulation of food intake, growth and carcase weight with both wet‐feeding treatments.

7. Providing food mixed with sufficient water to give a porridge‐like consistency significantly increased weight gains in each of the five experiments and significantly improved food conversion efficiency in three of the five. It is not necessary to withold drinking water in order to obtain this effect.     

Intermittent lighting and feeding schedules for broilers incorporating long periods of darkness

1. Intermittent lighting and feeding schedules incorporating long periods of darkness and periods without access to food were applied to growing broilers.

2. Birds exposed to a 2 h light(L): 10 h dark(D) lighting schedule with feeding restricted to the light periods ate significantly less food and grew more slowly than conventionally‐reared birds. Satisfactory growth and efficiency of food utilisation were obtained by allowing these birds access to food during the dark periods.

3. Altering the lighting schedule to 2L:6D resulted in birds with food intakes and growth rates similar to those reared conventionally, even when feeding was restricted to the light periods.

4. Releasing birds from the light and food restriction for the 2 weeks preceding slaughter resulted in greater food consumption which was not characterised by significantly better growth or food utilisation.

5. Feeding a diet of high energy or pelleting a diet of low energy during the period of restriction increased food intake and improved growth rate.

6. The response of broilers to intermittent lighting and feeding was not significantly influenced by ambient temperature within the range 16 to 35 °C or by the energy concentration of the diet fed before the introduction of the intermittent schedule.     

Response of broilers susceptible to ascites when grown in high and low oxygen environments

1. Broilers selected on the basis of food conversion efficiency or growth rate were grown under normal (21%) or varied (19%, 23%) oxygen environments.

2. Broilers selected for food conversion efficiency had greater growth rates and superior food conversion efficiencies than broilers selected for growth rate. No interactions between broiler strain and oxygen level were observed.

3. Increasing environmental oxygen level decreased N efficiency in both broiler strains. Nitrogen turnover was non‐significantly decreased.

4. Ascites may only occur when broilers are able to cope with small environmental adversities while maintaining optimal growth rates.     

Effect of a soluble polysaccharide (carboxy methyl cellulose) on the physico‐chemical conditions in the gastrointestinal tract of broilers

1. The effects of an indigestible soluble polysaccharide (carboxy methyl cellulose: CMC) on broiler performance (body weight gain, food and water intake) and on chyme characteristics (moisture content, viscosity, pH, osmolality and retention time) in broilers were studied.

2. In semi‐synthetic diets 0, 5.0 and 10.0 g/kg of cellulose was replaced by CMC on weight basis. These diets were fed to male broilers from 3 to 5 weeks of age.

3. When 10.0 g/kg CMC was included in the diet, food intake and body weight gain were reduced, compared to the 0, and 5.0 g/kg CMC diets. Food:gain ratio and water intake were increased at each CMC concentration. The significant quadratic response showed an increased response per 5.0 g/kg dietary CMC at the higher CMC concentration.

4. The viscosity in the supernatant of the chyme was linearly increased in all intestinal segments by CMC. A quadratic increase was observed in the crop. In the lower ileum, differences between the 5.0 and 10.0 g/kg CMC diets were not significant.

5. CMC increased the mean retention time of chromium in the duodenum and in the upper jejunum, and reduced the maximal rate of marker excretion. The transit time (first appearance of the marker in the excreta), however, was significantly reduced at the highest CMC concentration.

6. The osmolality of the intestinal fluid decreased less as the chyme moved from the duodenum into the lower ileum, with increasing concentrations of CMC.

7. The ileal pH was reduced linearly by the CMC content of the diet.

8. Based on a higher moisture content of the chyme in the CMC‐fed birds, and the higher jejunal and ileal osmolarities in those birds, it was concluded that the efficiency of both digestion and absorption was reduced by CMC inclusion in broiler diets.     

Vertical temperature profiles at bird level in broiler houses

1. The temperature in the close vicinity of commercial broilers was studied in relation to the setpoint temperature throughout the rearing period.

2. Mean temperature in the immediate environment of the chicks was 2.0°C lower than the setpoint of 1 d of age. During the first week this initial temperature difference gradually rose to 1.7°C above setpoint. At 18 d of age a further rise to a mean difference of 4.0°C above setpoint was measured. The difference then remained constant from 32 d of age until the end of the fattening period.

3. It was concluded that the chickens were actually brooded at 30°C. During the rearing period the ambient temperature in the close vicinity of the broilers gradually declined to 26°C.

4. During the finishing period, ambient temperature around the broilers was far above the value recommended for optimal food intake and growth.

5. These results are discussed in relation to heat generation and heat fluxes in the broiler houses.     

Use of four types of litter for rearing broilers

1. One hundred and forty four Shaver broiler chicks (Starbro 15) were reared from 4 d to 56 d of age on 4 types of litter: sawdust, paddy straw, sand and rice husk each spread to a depth of 75 mm.

2. Birds reared on rice husk litter showed the greatest food consumption, greatest weight gain, best food conversion efficiency and scored highest in production number.

3. Survivability was also highest with rice husk group (94.4%) but differences in this variable were not thought to be attributable to types of litter.

4. Breast blisters were found only in birds reared on sand (8.3%).

5. It was concluded that rice husk is a suitable litter for rearing broilers on the floor, particularly in paddy‐growing countries.     

Utilisation of ambadi (hibiscus cannabinus) meal by growing chickens

1. Experiments were conducted to compare the utilisation of ambadi meal with that of peanut meal in WL chicks and broilers.

2. Ambadi meal, either expeller‐processed (135.5 g and 271 g/kg) or solvent‐extracted (130.5 g and 261 g/kg), was incorporated at the expense of the peanut meal protein used in the reference diet (180 g/ kg) into diets which were fed to WL pullets (experiment 1) from 1 to 56 d of age. The weight gains and food efficiencies of the chicks fed on the ambadi meal and reference diets were similar.

3. With broilers (experiment 2) the weight gains were also similar, at all dietary concentrations of ambadi meal (89 to 356 g/kg), to those on the reference diet (235 g/kg peanut meal) from 14 to 35 d of age. However, food intake was higher on the ambadi meal diets and this resulted in significantly poorer food efficiency when compared to the reference diet.

4. High food intake and consequently low food efficiency was still evident in birds given ambadi meal diets even when ambadi meal replaced peanut meal on a digestible protein basis (experiment 4) or when ambadi meal (expeller or solvent‐extracted) was subjected to physical treatments such as soaking, autoclaving and pelleting (experiment 5).

5. The transit time of food through the gastro‐intestinal tract of broilers was faster when the diet contained ambadi meal than peanut meal. The higher food intake seen in broilers given diets containing ambadi meal could be the consequence of the fast rate of food passage.

6. Ambadi meal in diets for broilers resulted in significant increase (P<0.05) in the lengths of jejunum plus ileum and caecum. Fibre from the ambadi meal might have influenced the changes in the dimensions of gastro‐intestinal tract as well as in the transit time of food.     

The influence of three rapeseed meals and a mustard seed meal on egg and broiler production

A mustard seed meal free of oxazolidinethione and three rapeseed meals of low (C), medium (D) and high (E) oxazolidinethione contents were included at a rate of 12% in the diets of laying birds and of broilers. The control diets contained a similar quantity of protein as soyabean meal. In each experiment a further control group was given a suitable commercial diet.

The mustard seed meal and rapeseed meals D and E caused large and significant mortalities among laying birds. Macroscopic observations suggested that the main cause of death was probably liver haemorrhage.

Egg production, after correction for mortality, was significantly decreased by rapeseed meals D and E, and egg weight by the mustard seed meal. There were no significant treatment effects on food intake and therefore the weight of food needed for each egg produced followed fairly closely the pattern of egg production.

Overall egg production was depressed by mustard seed meal and by rapeseed meals D and E. Rapeseed meal C decreased production but not significantly.

Liver weights were not influenced by treatment, but thyroid weights of groups given rapeseed meals were significantly increased.

Broiler production was not significantly influenced either by mustard seed meal or by any of the rapeseed meals.     

Growth and food intake of broilers under various lighting regimes

1. Growth rates and daily food intakes of small, sexed groups of broilers were compared under different photoperiodic regimes during the period from 28 to 49 d of age.

2. Reduction in the duration of illumination did not impair growth rate.

3. The sexes showed a differential response to the treatments.

4. There was evidence that the enhanced performance of females was due to an improvement in food conversion efficiency.     

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.     

Use of ambroxol and bromhexine as mucolytics for enhanced diffusion of furaltadone into tracheobronchial secretions in broilers

1. Ambroxol and bromhexine were evaluated as mucolytics and to enhance the passage of furaltadone into tracheobronchial secretions (TBS) in chronic complicated respiratory disease‐affected broilers.

2. Viscosity of TBS was noticeably increased in the ambroxol‐treated birds and only slightly increased in the bromhexine groups; however, the physical (nature) of TBS was superior in the ambroxol‐treated broilers.

3. There was a clear increase in the passage of furaltadone into tracheobronchial secretions only in the ambroxol‐treated birds.

4. Everyday use of ambroxol in broilers is discussed.     

Effects of regular handling on growth in male and female chicks of broiler and layer strains

1. The effects of regular handling on growth and gain: food ratios in male and female chicks of layer (two strains) and broiler strains were examined from hatching to 3 weeks of age.

2. Growth was significantly enhanced by regular handling in broilers and the females of the layer strains and gain : food ratios were generally greater in the handled birds.

3. There were no significant treatment effects on growth or gain : food ratios in males of the layer strains.

4. Males had higher relative weight gains and gain : food ratios than females.     

Are genetically lean broilers more resistant to hot climate?

1. Genetically lean (LL) or fat (FL) male chickens were exposed to either high (32°C) or control (22°C) ambient temperature up to 9 weeks of age. They were fed on one of two isoenergetic diets differing in protein content: 190 or 230 g/kg.

2. At 22°C, weight gain of LL broilers was the same as in FL chickens, but at the high temperature LL birds grew to a greater weight than FL ones.

3. Food conversion efficiency was not affected by ambient temperature in LL chickens but was depressed in FL ones at 32°C.

4. Increasing dietary protein content did not alleviate heat‐induced growth depression irrespective of the genotype.

5. Gross protein efficiency was higher in LL chickens and was less depressed at 32°C than in FL birds.

6. Fat deposition decreased with increasing protein concentration at normal temperature in both genotypes; at high temperature, high protein content enhanced fatness, particularly in LL chickens.

7. Thus, genetically lean broilers demonstrated a greater resistance to hot conditions: this was indicated by enhanced weight gain and improved food and protein conversion efficiencies.     

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.     

Effect of access time to food on broilers fed on diets of differing nutrient concentration

1. In the two experiments on restricted feeding of broilers there were no interactions between dietary nutrient concentration and access time to food on either performance or carcass characteristics.

2. In the first experiment (winter), food denial for 8 h/d improved food conversion efficiency and increased dressing percentage. Increasing nutrient concentration increased growth rate; decreased food intake; and improved conversion efficiency.

3. In the second experiment (summer), food denial for 8 h/d tended to increase growth rate and to improve conversion efficiency, but not significantly. Increasing nutrient concentration had the same effect as in experiment 1.

4. It is concluded that restricted access to food generally improves food efficiency.     

Digestibility studies in broiler chickens: Influence of genotype,age, sex and method of determination

1. The influences of genotype, age and sex on droppings digestibility coefficients of a compound food were studied using male and female broiler chickens of three different genotypes at 2, 4 and 6 weeks of age.

2. Because the traditional method of determination of droppings digestibility coefficients of nitrogen may lead to systematic errors in estimating the feeding value of foodstuffs, a method is proposed to determine the ileal digestibility coefficients. The ileal method is compared with the droppings method for a mixed food and for two foodstuffs: wheat and solvent‐extracted soyabean meal.

3. Birds selected for efficient food conversion showed distinctly higher digestibility coefficients for all nutrients than birds selected for high growth potential or birds from a commercial strain.

4. The influence of age on digestibility coefficients was not consistent.

5. Female birds showed digestibility coefficients which were, in general, 3% higher than those of male chickens.

6. Interactions between genotype and sex and between genotype and age for energy metabolisability were the only interactions observed for digestibility measurements.

7. The method of determination influenced the amino acid digestibility coefficients of the mixed food and the relative feeding values of wheat and soyabean meal.

8. It is important to use well defined animals (genotype, sex, age) in evaluating foodstuffs.

9. The preferred method for determination of digestibility coefficients of nitrogen and amino acids is based on ileal sampling, although the differences in amino acid digestibility coefficients were small between methods.     

Twisted legs in broilers

1. The effect of various factors on the incidence of leg abnormalities, with particular reference to twisted leg, in broilers was studied.

2. The incidence of twisted legs was influenced by strain and for males was twice that for females. There was also a higher incidence in cages than on litter with the type of cage floor having an effect: broilers reared on floors of metal wire and perforated sheets had more leg problems than those reared on plastic mats and plastic‐covered wire.

3. Although vitamin and mineral supplementation had no effect on caged broilers, a restriction of metabolisable energy (ME) intake during the first 14 d after hatching halved the frequency of leg abnormalities compared with those fed ad libitum.

4. Studies of cage size and location of water suggested that a lack of exercise increases the incidence of leg abnormalities.     

Growth and laying performance of light‐hybrid pullets subjected to quantitative food restriction

1. Three degrees of quantitative food restriction producing body weights 88, 76 or 64% of controls at 20 weeks and three times of starting restriction 3, 6 or 9 weeks of age were compared with ad libitum‐fed pullets in a factorial experiment with 1800 light‐hybrid hens. Restrictions were applied such that the target weights were produced irrespective of time of starting.

2. Food intake was least when restrictions were started at 3 weeks.

3. Sexual maturity was delayed in proportion to the severity of restriction and resulted in lower percentages of small eggs.

4. Egg numbers decreased as restriction increased.

5. Mortality in restricted groups during rearing and laying was higher.

6. Optimal restriction was apparently intermediate between treatments producing 88 or 76% of ad libitum‐fed body weight. Body weight was so excessively affected by the most severe restriction that total production was adversely affected.

7. Restriction from 3 weeks was more profitable than restriction from 6 or 9 weeks, resulting in lower food cost during rearing and higher total egg production.     

Folic acid requirements of broilers

1. Dietary folic acid requirements of broilers were studied in three experiments using wheat‐ and maize‐based practical diets. Requirements were assessed on the basis of performance and metabolic criteria.

2. Growth and food conversion efficiencies were optimised with supplements of 1.5 mg folic acid/kg added to basal mash starter diets. The dietary folic acid requirement of broilers was estimated to be in the range of 1.7 to 2.0 mg/kg.

3. Red blood cell phosphoribosylpyrophosphate concentrations and dihydrofolate reductase activites did not show consistent changes over the range of dietary folate concentrations studied but plasma folate concentrations responded markedly to dietary folate supplementation.

4. Adding choline to diets in amounts greater than the normal requirement did not spare the requirement for folic acid.

5. It is suggested that minimum folic acid supplements for pelleted practical diets should be in the order of 2.5 to 3 mg/kg.