Constant photoperiods and eggshell quality in broiler breeder pullets

Broiler breeder pullets were exposed to constant 10-, 11-, 12-, 13-, 14- or 16-h photoperiods from 3 d of age. Egg weight, eggshell weight and shell thickness index were determined at 52 weeks of age. Egg weight increased by 0.31 g, shell weight decreased by 30 mg and shell thickness index decreased by 0.57 mg/cm2 for each one-hour increase in photoperiod. Whilst the changes in egg weight and eggshell thickness index might be overstated because eggs were collected at the same chronological time, the effect of time of egg-laying within the day was minimal in comparison, and did not negate the conclusion that egg weight increases, and shell weight and thickness index decrease with lengthening photoperiods. The effect of photoperiod on eggshell quality was not due to differences in the rate of lay between treatments. Shell weight was unaffected by time of lay.     

Quantification of reproductive changes and nutrient requirements of broiler breeder pullets at sexual maturity

1. 480 Broiler breeder pullets, kept in individual cages, were subjected to different rates of increase in food allocation during the period 18 to 30 weeks of age. From 80 g food/bird d at the start of the experiment, the 5 treatments comprised linear weekly increments in food allocation to reach a maximum of 150 g/bird d at 21, 23, 25, 27 or 29 weeks of age respectively. 2. Body weight, liver weight, fat pad weight and alimentary tract weight were influenced by the rate of increment in food allocation. 3. Rate of development of the oviduct and the ovary was not influenced by these treatments. 4. Although the amount of fat and protein contained in the liver increased most rapidly on the treatments where 150 g/bird d was attained first, by 25 weeks of age there were no meaningful differences in these two variables between treatments. It is unlikely, therefore, that a high protein intake during this period would allow sufficient protein or energy to be stored in the liver to sustain a higher egg output later in the laying period. 5. It is concluded that the amount of protein required by a broiler breeder pullet for maintenance and for growth during the pre-laying period is about 10 g/bird d.     

Effect of feeding low lysine starters and developers on growth,sexual maturity and subsequent performance of broiler breeder pullets 1

Pullets that were fed diets containing 0.53 per cent and 0.42 per cent lysine grew at a slower rate and matured later than those that were given adequate amount of lysine. The latter pullets converted their food more efficiently than did the restricted pullets with the exception of the group fed the ration containing 0.53 per cent lysine for the first 12 weeks. The restricted pullets consumed less food during the growing period. A smaller bird was produced on less food. The restricted pullets were also lighter than the control pullets at the end of the laying season. A saving in food costs is indicated because the smaller hen would require less food for maintenance.

There was a higher mortality in the pullets fed a ration containing 0.53 per cent lysine during the growing period. The mortality in the group fed the ration containing 0.42 per cent lysine from 7 to 22 weeks of age was the same as that of the control. There were no differences in mortality during the laying season that could be related to methods of rearing the pullets.

During the laying season, the highest rate of lay was obtained from hens which had been fed the ration containing 0.42 per cent lysine from 7 to 22 weeks of age. Hens fed on the ration containing 0.53 per cent lysine from o to 4, 8 or 12 weeks of age showed no improvement in rate of lay as compared with controls.

Hens fed the ration containing 0.42 per cent lysine from 7 to 22 weeks laid fewer small eggs at the beginning of the laying season than did hens receiving adequate amounts of lysine throughout or fed the ration containing 0.53 per cent lysine from o to 4, 8 or 12 weeks. The hens fed the latter ration laid smaller eggs throughout the laying season.

No differences were found between the fertility, hatchability or embryonic mortality of eggs obtained from hens fed on lysine deficient diets during growth and those fed on diets adequate in lysine.     

Disseminated Aspergillus flavus infection in broiler breeder pullets

Increased morbidity and mortality occurred in a 5-wk-old broiler breeder replacement pullet flock. The affected broiler pullet flock was housed on the first floor of a two-story confinement building. Mortality increased to 0.1%/day compared to the flock on the second floor, which had mortality levels of less than 0.01%/day. Clinical signs in the affected chickens included inactivity, decreased response to stimuli, and anorexia. No respiratory or neurologic signs were observed. On necropsy, affected pullets were dehydrated and emaciated and had disseminated variably sized single or multiple heterophilic granulomas that contained intralesional septate and branching fungal hyphae. Lesions were extensive around the base of the heart in the thoracic inlet and in the kidneys. Other affected organs included eyelid, muscle, proventriculus, ventriculus, intestine, liver, spleen, lung, and heart. Aspergillus flavus was cultured from the visceral granulomas. The source of flock exposure to the organism was not determined.     

Clinical encephalitis following avian encephalomyelitis vaccination in broiler breeder pullets

Twelve-to-fourteen-week-old broiler breeder pullets and cockerels from two different companies were found to have encephalitis 2 weeks after vaccination with avian encephalomyelitis (AE) vaccine. Histologic examination and virus isolation indicated that affected chickens had AE. All chickens had been vaccinated with either one of two serials of AE vaccine approximately 2 weeks before the onset of clinical signs.     

Arginine--lysine interrelationships in the nutrition of broiler breeder pullets during the developmental period

Pullets were fed on diets containing various concentrations of lysine and arginine from 7 to 18 or 20 weeks. Thereafter a conventional layers' diet was fed and egg productivity measured—in the first two experiments for ten, and the third for six 28‐d periods. Pullets were also fed on a standard growers' type diet on a “skip‐a‐day” or on a 20% restriction basis in the third study.

Growth and age at sexual maturation were directly related to the lysine content of the diet and to a lesser extent to the arginine content. Pullets fed on diets with the lower concentrations of lysine and arginine required less food during the growing period and matured later than those fed on a complete diet ad libitum. They also laid more eggs and required less food to produce a dozen eggs. Higher egg production was obtained in the third experiment with low concentrations of lysine and arginine than with the “skip‐a‐day” or the restricted feeding programmes. Pullets fed on the normal grower diet ad libitum produced the smallest eggs in the first and third experiments with no difference in egg size in the second experiment. Pullets maintained on the “skip‐a‐day” or the restricted feeding programme also had a larger egg size than the control group fed on the same diet on an ad libitum basis.

An ingredient effect was observed in the third experiment. Of two diets containing identical calculated values of lysine and arginine, the one containing distillers' dried grains with solubles was superior to the one with soybean meal as regards weight at 20 weeks of age, amount of food consumed during the period 6 to 18 weeks of age and percentage egg production. It is possible that the soybean meal contained a better balance of amino acids than did distillers' dried grains with solubles which resulted in a significant increase in body weight at 20 weeks of age and a subsequent lower level of egg production. These data indicate that it would be best to use ingredients with an imbalance of amino acids in the protein as sources of lysine and arginine in pullet grower diets.

There were no differences in the mortality of the birds during the laying period which could be related to dietary treatment during the pullet growing period.     

Temporary exposure of prepubertal,somatically-mature broiler breeder females to stimulatory photoperiods

1.?Individually-caged Ross 308 broiler breeders were transferred temporarily at 147 d from 8 to 14-h photoperiods and back to 8 h at 5-d intervals from 5 to 25 d and at 32 d. Control birds were maintained on 8 h or transferred permanently to 14 h.

2.?Five long days had minimal effect on age at first egg, between 10 and 25 long days progressively accelerated sexual development, and maximum advance was achieved by 32 long days. However, a model involving the ogive of a normal distribution with a mean of 14 long days and an SD of 5.3 indicated that 28 long days would be sufficient to maximise sexual development.

3.?The similarity of this model for broiler breeders with one previously produced for egg-type pullets suggested a common physiological mechanism for photosexual responses to two opposing changes in photoperiod.     

Performance of broiler breeder pullets as influenced by composition of grower and layer diets 1

An experiment was conducted to determine the influence of three grower systems upon the subsequent performance of broiler type breeder pullets. The grower systems were full feeding a 10 per cent protein diet, full feeding a 16 per cent protein diet, and a skip‐a‐day feeding of the 16 per cent diet. One‐third of the pullets fed according to each of the feeding programmes were fed on each of three different layer diets. The use of the low protein and the skip‐a‐day feeding resulted in delaying age at sexual maturity. Total rate of egg production was not affected by the grower diet; however, the number of “ settable “ eggs was increased when maturity was delayed.

Performance of the laying hens was not influenced by the composition of the layer diet. Fertility or hatchability was not influenced by composition of either the grower or layer diet. These data would indicate that the low protein diet or the skip‐a‐day feeding system can be effectively used with feeding replacement broiler type birds.     

Changes in light intensity can influence age at sexual maturity in domestic pullets

1. Shaver White and ISA Brown pullets were reared to 140 d in groups of 8 in cages on a 10-h photoperiod of incandescent light and maintained at an illuminance of 3 or 25 lux, or transferred from 3 to 25 lux or from 25 to 3 lux at 63 or 112 d of age. 2. There was no significant difference in sexual maturity, measured as eggs per 100 bird.d at 139 and 140 d, for ISA Brown maintained on 3 or 25 lux, but Shaver White pullets exposed to constant 3 lux matured significantly later than those maintained on 25 lux. 3. In Shaver Whites, sexual maturity was significantly delayed by an increase from 3 to 25 lux at 63 and 112 d, and advanced by a decrease from 25 to 3 lux at 112 d. Sexual maturity of ISA Browns was not significantly affected by a change in illuminance at 63 or 112 d, though responses were in the same direction as for Shaver Whites. 4. In both breeds, total feed consumed to 112 d was higher for birds on 3 lux than 25 lux, but lower between 112 d and 140 d when birds on 25 lux underwent rapid sexual development. In both breeds, body weight at 63 d was higher for birds exposed to 3 lux than 25 lux, but body weight gain thereafter was similar for the two light intensities. 5. In both breeds, plasma luteinising hormone (LH) concentration at 63 and 112 d was lower in birds maintained on 3 lux than 25 lux. At 63 and 112 d, transfers from 25 to 3 lux depressed, whereas transfers from 3 to 25 lux at 63 d, but not at 112 d, increased plasma LH. 6. Advances or delays in sexual maturity induced by changes in illuminance were not correlated with differences in feed intake, body weight gain, or with changes in plasma LH. 7. One possible explanation for the inverse relationship between the direction of change in illuminance at 63 and 112 d in pullets exposed to a 10-h photoperiod and the age at which they became sexually mature is that changes in light intensity and/or spectral composition affect the entrainment of the circadian rhythm of photoinducibility, to effect a phase shift in the photoinducible phase and/or the responsiveness of phototransduction pathways.     

Light intensity can influence plasma FSH and age at sexual maturity in domestic pullets

1. Shaver White and ISA Brown pullets were reared to 140 d in cage groups of 8 on a 10-h photoperiod of incandescent light and maintained at an illuminance of 3 or 25 lux, or transferred from 3 to 25 lux or from 25 to 3 lux at 63 or 112 d of age. 2. Plasma follicle stimulating hormone (FSH) concentration at 63 and 112 d was higher in both breeds for pullets maintained at an illuminance of 25 lux compared with 3 lux. After 2-4 d, and relative to constant-illuminance controls, plasma FSH increased significantly for ISA Brown transferred from 3 to 25 lux at 63 d and for Shaver White transferred at 112 d. Irrespective of genotype, plasma FSH for pullets given a decrease in illuminance at 63 or 112 d showed a tendency for less change than did constant-illuminance controls. 3. There was no significant difference in sexual maturity for ISA Brown maintained on 3 or 25 lux, but Shaver White pullets exposed to constant 3 lux matured later than those maintained on 25 lux. Shaver White matured later following an increase from 3 to 25 lux at 63 and 112 d, and earlier subsequent to a decrease from 25 to 3 lux at 112 d. ISA Brown pullets were not significantly affected by a change in illuminance at 63 or 112 d, though their responses were in the same direction as Shaver White. 4. Changes in plasma FSH in the 2- to 4-d period following a change in illuminance at 63 or 112 d were not significantly correlated with sexual maturity.     

Photorefractoriness in broiler breeders: sexual maturity and egg production evidence

1. Photorefractoriness was assessed in two lines of broiler breeders. In one trial, male-line and female-line pullets were reared on the floor and transferred to individual cages at 15 weeks. Birds were either maintained on 8-, 11- or 16-h photoperiods or transferred from 8- to 16-h photoperiods at 67 or 124 d. In the second trial, female-line pullets were concurrently housed in the same rearing facilities as trial 1 and transferred to adult floor-pens at 12 weeks. These birds were either maintained on 11- or 16-h photoperiods or transferred from 8- to 11-h or from 8- to 16-h photoperiods at 140 d. 2. In the cages, male-line and female-line birds responded similarly to the lighting treatments, but with the male-line maturing 1 to 2 weeks later than the female-line in each case. Birds on constant 11-h photoperiods matured 3 to 8 d earlier than constant 8-h birds, but 3 weeks earlier than constant 16-h birds. Birds photostimulated at 67 d matured at a similar time to constant 16-h birds, but almost 7 weeks later than those transferred from 8 to 16 h at 124 d. In the floor facilities, constant 11-h birds matured 3 weeks earlier than constant 16-h birds, but almost 2 weeks later than either of the photostimulated groups. Birds transferred from 8 to 16 h matured 4d earlier than those transferred from 8 to 11 h. 3. Caged birds maintained on 16 h or transferred from 8 to 16 h at 67 d laid at least 24 fewer eggs, and had more hens not laying at 58 weeks, than birds maintained on 11-h days or those transferred from 8 to 16 h at 124 d. In the floor-pens, constant 11-h and both photostimulated groups produced about 20 more eggs to 56 weeks of age than the constant 16-h controls. 4. Collectively, these findings indicate that conventionally managed broiler breeders exhibit photorefractoriness. Additionally, a combination of photorefractoriness and controlled feeding appears to prevent broiler breeders from being photoresponsive until at least 10 weeks of age, and to cause some individuals still to be photoperiodically non-responsive at 18 weeks.     

A model for the effect of constant photoperiods on the rate of sexual maturation in pullets

1. This paper reviews evidence from 15 experiments, reported over a span of 44 years, in which pullets were reared from hatching to sexual maturity on 2 or more constant photoperiods. 2. The evidence strongly indicates that earliest age at first egg (AFE) was observed when pullets were held on constant 10 h days (though earlier maturity is easily induced by increasing the photoperiod during rearing). The pair of equations which best describe the relationship between AFE (y,d) and photoperiod (x,h) are for x < 10 h, y = 175.8- 1.731x; for x > 10 h, y=155.5 + 0.301x. 3. This 2-straight-line model, hinged at 10 h, should be used in preference to curvilinear models published earlier, which wrongly predict that pullets reared on long days (14h to 17h) mature faster than birds reared on constant 10 h.     

Restricted feeding of broiler breeder pullets during the rearing period and its effect on productivity and breeding

A total of 2000 broiler breeder pullets was used for an experiment comparing two levels of restricted feeding from 6 to 20 weeks with three levels of low‐lysine feeding from o to 12 weeks of age. The object of the experiment was to obtain matching body weights at 20 weeks of age between the two levels of quantitative restriction and the highest and lowest levels of lysine feeding and to compare subsequent biological performance during lay. A control treatment was included in which birds were fed ad libitum at all stages.

Both methods of nutrient restriction reduced intake to 20 weeks of age. From 1 d to 60 weeks of age total food intake was reduced in proportion to the degree of restriction applied during the growing stage.

Sexual maturity was delayed by both methods of restriction, though low‐lysine diets produced a greater delay than quantitative restriction. Production of total eggs and of settable eggs was increased by both quantitative food restrictions and by the least severe of the lysine‐deficient diets. Following quantitative restriction egg size and fertility were both improved, but these advantages were not obtained by lysine restriction.

Mortality and culling were mainly influenced by a high incidence of “rupture of the gastrocnemius tendon “ which occurred exclusively in pullets fed lysine‐deficient diets during rearing.

It is concluded that quantitative restriction is to be preferred because of its advantageous effects on egg weight, rate of lay and fertility, and because it avoids the high mortality rate found with severe lysine restriction.     

Control of the development of the ovarian follicular hierarchy in broiler breeder pullets by food restriction during rearing

1. The increase in the numbers of yellow and of white ovarian follicles was studied from 10 weeks of age to sexual maturity in broiler breeder pullets fed ad libitum and on a restricted intake. The growth of follicles greater than 1 mm diameter commenced at 14 to 16 weeks of age in ad libitum birds and at 22 to 24 weeks in those which were restricted. 2. In a second experiment, groups of birds restricted from 4 d of age were transferred to ad libitum feeding at 2-week intervals and examined at first egg. The numbers of yellow follicles at first egg were not affected by restriction to 14 weeks of age but, thereafter, declined linearly with time on restriction. 3. In the second experiment there were no comparable responses in the numbers of white follicles or in the rates of atresia. 4. Food restriction to 22 weeks of age produced about half the response in numbers of yellow follicles as restriction continued to point of lay (27 to 32 weeks of age). In practical situations, the results suggest that food intake should be restricted up to the onset of lay and then increased in relation to the rise in egg production. 5. Atresia was greatest in white follicles 3.15 to 6.30 mm diameter and was less outside this range.     

Pinealoma in a broiler breeder

An incidental central nervous system tumor was found in a broiler breeder. The cellular mass was histologically similar to the normal pineal gland, but it was characterized by a decreased ratio of follicular/parafollicular cells, a relative increase in mitoses, a size three times greater than a normal pineal gland, and growth and expansion into adjacent cerebellar tissue. These characteristics warranted a diagnosis of pinealoma rather than pineal gland hyperplasia.     

评估肉用种鸡

对于种鸡场的管理人员来说，如何评估肉用种鸡、监测数据是否准确、鸡群每日饲喂多少料量、何时转群、每百只母鸡配给多少公鸡，这些信息对一个种鸡群的成功与否起着至关重要的作用。业内大多数同行都认同，管理种鸡群最重要的一项指标就是鸡群的平均体重，或者说，鸡群对喂料水平的反馈。１如何对种鸡进行称重肉种鸡的个体称重应越早越好，最好从第２周龄开始。对某些称重器来说，鸡只只有达到２２０～３００g时才能有效地使用。早一些对鸡只进行称重可以确定所饲养的鸡群属于哪种类型。年轻种鸡群所产的雏鸡势必比产蛋中期或产蛋后期所产…     

Effects of body weight at sexual maturity and the degree and age of restriction during rearing on the ovarian follicular hierarchy of broiler breeder females

1. Groups of 18 birds were reared to 10 different body weight targets in a randomised block experiment to assess the effect of body weight and the degree and age of restriction on ovarian function at first egg.

2. There was no effect of age at restriction (15 to 18 compared with 19 to 22 weeks) on the number of yellow follicles.

3. The treatment with the larger body weight of two groups given the same degree of restriction (maintenance) had more follicles than the treatment which had a smaller body weight.

4. There was a positive linear relationship between the number of yellow follicles and body weight and food intake. Addition of the weight of fat or age at first egg to the model increased the residual mean squares.

5. The proportion of atresia among yellow follicles and the incidence of internal ovulation increased with body weight at first egg.

6. It was concluded that the physiological processes occurring during rearing which underlie ovarian function are reflected solely in the body weight and food intake of broiler breeders at first egg.     

Tenosynovitis in broilers and broiler breeder flocks

Tenosynovitis in commercial broiler breeder flocks, characterised by severe lameness, resulted in malnutrition and eventual culling of these chickens. Histologically there was metaplasia of tendons, tendon sheaths, connective tissues and infiltration with heterophils. Although Staph. aureus was isolated from some specimens, it is probable that the condition is of viral origin: the virus has not yet been isolated.