Effects of the caecal nematode Trichostrongylus tenuis on egg-laying by captive red grouse

Captive hen red grouse infected with Trichostrongylus tenuis larvae started to lay later in spring and laid fewer eggs at a slower rate than uninfected hens. March-infected hen grouse showed greater effects than December-infected ones, probably because developing larvae were more pathogenic than adult worms. The mechanism by which parasites interfered with egg production involved reduction in food intake. Infected hens also gained less weight than controls before laying.     

Choice feeding of the replacement pullet on whole grains and subsequent performance on laying diets

From 8 to 20 weeks of age crossbred pullets were offered a protein concentrate plus either wheat, millet or paddy rice as crushed or whole grain. These pullets were then fed on three laying diets which differed in either methionine content or bulk density. In the growing period pullets given whole grains were heavier, and ate more protein-concentrate and hard grit than those given crushed grains. In the laying period they matured earlier, laid more eggs and utilised food more efficiently than the others. Pullets fed on wheat consumed more hard grit and utilised food more efficiently than those given millet or paddy rice. Pullets fed on millet had a higher linoleic acid content in their livers and laid larger eggs than those reared on wheat. Pullets reared on paddy rice matured later and laid heavier eggs than those reared on wheat. Methionine content and bulk density of the laying diets had no effect on egg production.     

Food intake of normal and internal layers: a question of energy balance

1. Normal adult laying hens, which produced 41 g egg/hen d, ate 30 g/hen d more of a pelleted diet than did hens of the same age which were induced to lay eggs internally by surgical treatment of their oviducts. This implied that 0.336 MJ metabolised energy was required to produce 0.251 MJ egg, or 75% efficiency of utilisation of ME. 2. This may not have represented the true cost of egg production because both normal and internal layers gained weight during testing, at slightly different rates, suggesting that they did not regulate energy balance precisely. 3. The internal layers were less active and also saved energy by resorbing egg material. Their greater body weight was due to unresorbed eggs and to heavier fat deposits, which were accompanied by higher concentrations of lipid in the blood. 4. It was estimated that internal layers ate 4 to 5% more per day than was required to maintain the same lipid status as normal layers; these data provide further evidence that poultry do not regulate their food intake precisely by energostatic or lipostatic means.     

Food intake of the laying hen following crop loads of maize oil and other nutrients

The metabolisable energy (ME) of the diet of laying hens at an ambient temperature (Ta) of 20 degrees C was abruptly changed from 10.9 MJ/kg to 12.9 MJ/kg, or vice versa. Food intake during the next 14 d was significantly reduced by the low ME diet and was increased by the high ME diet, that is, the expected compensatory changes in food intake did not occur. Laying hens given the same change of diet as above but kept at 32 degrees C did not show any change in food intake within 14 d. Thus ME intake increased with the high ME diet and decreased with the low ME diet. Daily doses of 10 ml maize oil/kg body weight given directly into the crop of laying hens at a Ta of 20 degrees C, resulted in an immediate, significant, reduction of food intake such that total ME intake remained the same as with normal feeding. Daily doses of 3 ml maize oil/kg, given as before, resulted in an immediate, significant, reduction in food intake at a Ta of 20 degrees C but at a Ta of 32 degrees C food intake remained unchanged; consequently daily ME intake increased. Loading the crop with glucose or sucrose, at Ta 20 degrees C, in quantities which provided a similar ME as 3 ml maize oil/kg, reduced food intake but the adjustment was less precise and daily ME intake increased. Loading with glycerol or protein hydrolysate decreased both food and ME intake. Crop loads of starch were as effective as maize oil in bringing about a significant and compensatory reduction of food intake. Similar volumes of water or liquid paraffin placed in the crop did not affect food or ME intake. A similar weight or cellulose placed in the crop reduced food and ME intake.     

Effect of method and phase of nutrient restriction during rearing on productive performance of light hybrid pullets and hens

1. An experiment was conducted to study the effect of method (low-lysine or quantity of food) and phase (starter or grower) of restriction during rearing on growth and laying performance in Leghorn hybrids. 2. A reduction in body weight gain was achieved by feeding pullets a low-lysine diet in either the starter phase (0-6 weeks of age: 4.0 g/kg digestible lysine) or the grower phase (7-18 weeks of age: 3.0 g/kg digestible lysine). 3. In each phase, the lysine restriction was compared with a daily food restriction, in which pullets received a quantity of food sufficient to pair-gain with their lysine-restricted counterparts. 4. The delay in onset of production was greatest in the lysine-restricted birds, for both phases of restriction. 5. Hens restricted during the grower phase laid heavier eggs than those restricted during the starter phase, despite having similar body weights at end of rearing. This effect was not influenced by the restriction method. 6. Production traits varied between pullets reared on different feeding strategies up to similar body weights at 18 weeks and onwards. It is concluded that body weight is not the only factor determining laying performance.     

Performance of laying hens as affected by split time and split composition dietary regiments using ground and unground cereals

A factorial experiment was conducted to study the effects on the performance of White Leghorn X Australorp laying hens of diets based on unground cereal grains, small morning and large afternoon meals, and morning and afternoon meals of different composition. From 10 to 21 weeks of age the pullets' food intake was restricted, using either a diet in which the wheat fraction (600 g/kg) was unground or a fully ground diet of similar composition. In the laying period the birds received either a diet (U) in which the limestone was granulated and most of the cereal fraction (wheat and oats or wheat and sorghum) was unground or a fully ground diet (G) of similar composition. Both laying diets were offered ad libitum (A), with 25% issued in the morning and 75% in the late afternoon (T) or as a protein concentrate (250 g/kg of total diet) in the morning and cereal/limestone fraction (750 g/kg) in the late afternoon (C). Rearing and laying performance were unaffected by rearing diet. Laying diet U resulted in a 5.2% increase in food intake and a 0.9 g increase in average egg weight compared with diet G. From 21 to 56 weeks of age, when the cereal/limestone fraction of the diet included oats (240 g/kg of total diet), diet U resulted in fewer (4.8/bird) eggs and a lower financial margin than diet G. From 56 to 80 weeks of age, when oats were replaced by sorghum, this trend was reversed (-3.5 eggs). Birds on diet C produced fewer (16.9) eggs of lower (1.5 g) average weight than birds on diet A, ate less (1.39 kg) food and had a lower financial margin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of artificial light sources and lighting programmes for laying hens on long ahemeral light cycles

Three lighting treatments were given to laying hens, for which the bright and dim light of 28-h ahemeral light cycles was provided by incandescent (tungsten filament) lamps only or by combinations of tubular fluorescent or compact gas-discharge lamps with incandescent lamps. There were no differences in entrainment (the proportion of eggs laid in 4, 6 or 8 h modal periods) between the three bright:dim treatments. A fourth ahemeral lighting treatment in which the dim lights were extinguished except during a designated work period (09.00 h to 12.00 h daily) was termed bright:dim:dark. Hens given the bright:dim:dark treatment showed an increased entrainment compared with the three bright:dim light treatments. There were no differences (P greater than 0.05) in egg numbers or mean egg weight between all 4 lighting treatments. Birds given the bright:dim:dark treatment tended to have a lower (P greater than 0.05) food intake compared to the three bright:dim treatments.     

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

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

The effect of egg formation and laying on the food and water intake of brown leghorn hens

Food and water intakes of four caged Brown Leghorn hens were studied on a daily and hourly basis in relation to egg formation. In addition the food intake of two similar hens was studied using a Skinner box which provided a more detailed record of ingestive behaviour in a non‐social situation in which social interactions might not mask the relationship between food intake and physiological needs. Food intake was greater on days on which ovulation occurred than on days during which there was neither ovulation nor oviposition. Water intake was greater on days during which ovulation occurred than on days with oviposition but no ovulation. On this latter type of day (laying day) food intake was greater than on days without ovulation and oviposition (resting day). Both food and water intakes were depressed for 1 to 2 h before oviposition, but ingestion increased during the hour of laying and remained high for 1 to 2 h.     

The performance of cross‐bred hens given free choice feeding of whole grains and a concentrate mixture and the influence of source of xanthophylls on yolk colour

1. Cross‐bred hens were offered, from 25 to 73 weeks of age, diets based on either wheat or barley in the form of either a mash or as whole grains plus a concentrate mixture; four sources of xanthophylls were also compared.

2. Wheat reduced food intake by 8%, increased efficiency of food conversion and live‐weight gain while barley increased litter moisture content, and, during the first half of the laying year decreased egg production by 3.3% and yolk colour by 4%.

3. Hens offered whole grains ate 11% less food, converted food into eggs more efficiently, were heavier and laid larger eggs than those given the mash diets.

4. With whole grains yolk colour was less than with mash diets during the first 24 weeks of lay but this was reversed during the last 24 weeks of lay.

5. Either canthaxanthin or citranaxanthin or β‐apo‐8'‐carotenoic acid ethyl ester plus canthaxanthin in diets containing lucerne meal produced eggs with acceptable yolk colours.     

Effect of daily feed intake in laying period on laying performance, egg quality and egg composition of genetically fat and lean lines of chickens

1. The objectives of this study were to evaluate the effects of feed intake on laying performance, egg quality and egg composition in a Fat line and a Lean line during the laying period (34 to 54 weeks of age). 2. The experiment was a 2 × 2 factorial design with two dietary intake levels (nutrition recommendation and 75% of recommendation) and two broiler genotypes (Fat line and Lean line). Hens (384 of each line) were randomly divided at 23 weeks of age into 4 treatments, with each treatment represented by 12 replicates of 16 birds each. The experiment started when the rate of lay reached 5% and continued until 54 weeks of age. 3. The results indicated that there was a significant interaction between daily feed intake and genotype on egg production, egg weight, percentage yolk, yolk/albumen ratio and yolk cholesterol content. Fat line hens produced significantly more eggs and had a lower incidence of cracked eggs than the Lean line hens. The reduction in feed intake decreased egg weight and increased egg production, egg-shape index and cholesterol content of yolk significantly.     

Response of laying hens to asymmetrical interrupted lighting regimens: physiological aspects

1. There were no significant differences in the mean time of oviposition, distribution of ovipositions over the 24 h or proportion of eggs laid in the modal 8 h when conventionally-lit hens were compared with hens which received interrupted lighting with the same apparent daylength. 2. Intermittently-lit hens performed 25% less feeding activity than conventionally-lit hens, but without a significant reduction in mean food intake. There were genetic differences in response of feeding rate to interrupted lighting. 3. Intermittently-illuminated hens consumed about 20% of their food during the scotoperiods which interrupted the apparent day of a 1.5L:0.5D:10(0.5L:0.5D):4L:8D regimen, although there was significant genetic variation from 10 to 22%. None of the genotypes ate during the 8-h night. 4. Across 4 genotypes neither crop weight nor rate of crop emptying was affected by the lighting treatments, although a heavier mean crop weight under interrupted lighting approached significance in one breed (P less than 0.10). 5. Interrupted lighting did not cause any ocular disorders.     

Effect of age and body weight of Greater Rhea (Rhea americana) females on egg number, size and composition

1. A study was conducted to evaluate how body weight and age of each female are related to the number and physical and chemical characteristics of the eggs produced throughout a breeding season in a captive-bred population of Greater Rheas (Rhea americana). 2. Reproductive performance of 15 females of three age classes (5 individuals per class) was monitored; female body weight was recorded before laying-onset. All the eggs laid were collected and identified, and different morphometric variables, percentage of components and fatty acid composition were determined. 3. The earlier the female started egg-laying, the longer the laying period and the greater the overall number of eggs produced. The onset of egg-laying in turn seemed to be related to the attainment of a high body weight. 4. Except for length, the values of the morphometric variables of the egg and unsaturated fatty acids (palmitoleic, oleic and linoleic) increased with female age. 5. High body weight was associated with low palmitic and palmitoleic fatty acids and high linoleic, linolenic and total unsaturated fatty acids. 6. Live weight and age of females can determine several physical and chemical characteristics of eggs.     

Production responses of layer strain hens to food restriction during rearing

Production responses of laying hens to food restriction during rearing were measured in two trials. Food was restricted by two methods: time restriction (TR, food continuously available for 24 to 30 h each 72 h) and proportion restriction (PR, daily allocations of about 60 to 70% of that consumed by ad libitum fed birds (F]. The rearing treatments were applied from 42 to 162 d and from 56 to 168 d of age in experiments 1 and 2 respectively. All birds were fed ad libitum in the laying period to 437 d and 476 d of age in experiments 1 and 2 respectively. Body weight was reduced significantly in both experiments by both methods of restriction, but more so by TR. Marked compensatory growth accompanied the high food intake following the end of food restriction. There was a significant increase in average egg weight concommitant with a change in the relationship between egg weight and age. Possibly this is due to an altered pattern of food intake at onset of lay.     

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.     

日粮氨基酸平衡条件下大午金凤商品代蛋鸡产蛋高峰期粗蛋白质需要量研究

本试验通过研究日粮粗蛋白质（CP）水平对大午金凤商品代蛋鸡产蛋高峰期生产性能和蛋品质的影响,确定其CP需要量。试验选取31周龄大午金凤商品代蛋鸡480只,随机分入4个处理组,每组12个重复,每个重复10只蛋鸡,4个处理CP水平分别为13.5%、14.5%、15.5%、16.5%。预试期7 d,正试期63 d。试验期间每天记录蛋鸡产蛋数、蛋重和不合格蛋数,每2周以重复为单位统计采食量,计算平均日采食量（ADFI）和料蛋比（F/E）;试验第6周时,每个重复取3枚鸡蛋测定蛋品质。结果表明：①日粮CP水平对蛋鸡日产蛋量、日采食量、料蛋比有显著影响（P<0.05）。16.5% CP组的日产蛋量、平均日采食量均显著高于13.5%和14.5% CP组（P<0.05）,且随着日粮CP水平的提高日产蛋量呈线性增加（P<0.05）;16.5% CP组的料蛋比显著低于13.5%、14.5%和15.5% CP组（P<0.05）。②日粮CP水平对蛋壳占比、蛋黄颜色有显著影响（P<0.05）,13.5% CP组的蛋壳占比显著高于16.5% CP组（P<0.05）,且随着日粮CP水平的提高呈线性降低（P<0.05）;13.5% CP组的蛋黄颜色显著高于16.5% CP组（P<0.05）,且随着日粮CP水平的提高蛋黄颜色呈线性降低（P<0.05）。建立料蛋比与日粮CP水平之间的回归曲线（y＝275x²-86.4x+8.7356）,经计算,获得最小料蛋比的日粮CP需要量为15.7%。结合本试验生产性能和蛋品质,推荐大午金凤商品代蛋鸡产蛋高峰期CP需要量为15.7%。     

Effect of breeder age and breeding season on egg production and incubation in farmed ostriches

(1) This research was carried out to investigate changes in egg production and hatchability as influenced by age and breeding season of 10 trios (two females, one male) of ostrich (Struthio camellus) during 1998 to 2002. (2) Breeding season affected number of eggs laid per female per season, average egg weight, length of laying period and clutch sequence. (3) The number of eggs laid per female per season was 25 in the first breeding season and 57 by the fifth breeding season. The laying period lasted 169 d in the first season whereas it was 210 d by the fifth season. The breeding season became longer year by year. (4) The number of clutches was two in the first season, three in the second and 4 in the later breeding seasons: the mean interval between cycles was 9 to 10.6 d and the mean number of eggs in one cycle varied from 12 to 14.4. (5) The breeding season affected the hatchability of fertile eggs, chick weight at hatching, hatchability of total eggs, fertility, malpositioned embryos, deformed chicks and assisted chicks during hatching. The first 4 variables increased and the last three decreased, with each breeding season. (6) Weight loss of eggs and length of incubation were unaffected by the breeding season. Hatchability which was 64.3% in the first season increased progressively and reached 73.1% in the fifth breeding season.     

影响矮小型蛋鸡饲料转化率的相关性状遗传参数估计

直接影响蛋鸡饲料转化率性状的因素包括采食量、平均蛋重和产蛋数。本试验测定了60个家系600只矮小型蛋鸡产蛋高峰期和产蛋后期的相关性状,计算产蛋高峰期各性状的遗传力和遗传相关。结果表明,日耗料和平均蛋重遗传力分别为:0.574和0.364;总蛋重、产蛋数和料蛋比的遗传力较低,分别为0.079,0.042和0.150。料蛋比与日耗料为较高的遗传正相关,而与平均蛋重、总蛋重和产蛋数均为弱正相关。产蛋高峰期和产蛋后期各性状的相关性为中等。     

The effect of feeding low‐protein diets to pullets from hatch to point‐of‐lay and the quantitative restriction of food during the subsequent laying period

Pullets from two commercial breeds were fed on diets of similar energy content but with 19% or 16% crude protein to 8 weeks of age and from 8 to 20 weeks of age on one of three isoenergetic diets containing either 12, 14 or 16% crude protein. At 20 weeks the birds were offered a conventional layers’ diet containing 16% crude protein either ad libitum or on a daily food intake of 100 g for a further 32 weeks.

The results indicate that with certain breeds the dietary protein levels can be lowered to approximately 16% during the o to 8‐week period and to approximately 12% during the 8 to 20‐week period without adversely affecting egg production. However, variations in the laying performance of the different breeds appear to be dependent on the amount of protein fed in the first eight weeks of life. Significant breed effects were observed throughout the experiment and although restricted feeding during the laying period substantially reduced the food intake it also had a detrimental effect on the rate of egg production and on the total weight of eggs produced.     

Nitrogen retention and performance of brown laying hens on diets with different protein content and constant concentration of amino acids and energy.

1. The aim of this study was to determine the nitrogen balance and the performance of laying hens fed on diets with a protein content lower than the diets currently used in commercial practice but with adequate concentrations of lysine, sulphur amino acids, tryptophan and threonine. 2. Ninety-six Hy-Line Brown hens, 24 weeks old, were divided into 3 groups of 8 replicates and received, for 16 weeks, diets formulated to have 3 different protein concentrations: 170 (control), 150 and 130 g/kg CP and the same energy content. For each protein concentration, the contents of lysine, methionine, methionine+cystine, tryptophan and threonine were maintained at minimum requirement concentrations by supplying synthetic amino acids. 3. In the first half of the trial, egg production and egg weight were similar in all groups. From the 9th week onwards group 150 CP laid heavier eggs and had a slightly lower egg deposition and total mass. Food conversion ratio was best in the control group. 4. Nitrogen intake was related to the protein concentration of the diet, the food intake being almost the same in the 3 experimental groups. Faecal nitrogen content significantly and linearly decreased with reduction in dietary protein content and was about 50% of the intake. Considering the nitrogen faecal/intake ratio, the 150 CP group showed better nitrogen utilisation at each sampling time.