The relationship between hatching egg weight and subsequent performance of broiler chickens

Small eggs constitute a high proportion of the eggs laid by pullets. The literature shows that chick hatching weight is strongly correlated with egg weight, but evidence on the influence of egg weight on hatchability and subsequent performance of chicks is less certain.

The aim of this experiment was to determine the profit returned at 12 weeks by broiler chickens hatched from eggs ranging in weight from 44 g. to 58 g. at one gram intervals and to determine how competitive and separate rearing might modify the relationship.

A total of 6000 eggs were collected during 10 days from a 28‐week‐old, broiler breeding flock and graded into the above mentioned egg weight classes. From these, a total of 3480 day‐old broilers were housed. Each egg weight class was equally represented and balanced for sex.

Hatchability and fertility showed no consistent trend with egg weight for eggs above 46 g., but below the 47 g. level there was a trend of declining fertility and hatchability.

A strong positive relationship was found between the weight of the chick at 1 day of age and egg weight for both males and females with no significant difference overall in body weight between the two sexes.

Body weight to 12 weeks was found to be strongly related to egg weight, in a linear fashion, though this influence declined with age.

There was a greater influence of egg weight on body weight at all ages in the separate rearing treatment compared with competitive rearing but this was not significant after 10 weeks.

Egg weight had an important bearing on body weight and profit at 12 weeks, but no effect on food conversion or mortality.

The increased profit over food costs per 100 day‐old chicks was found to be 52.75 cents for the separately reared birds respectively for each 3 g. increase in egg weight.     

Carcase downgrading of broiler chickens

1. Data were collected (1981‐82) from four commercial processing plants in different states of Australia. Total downgrading was classified into damage occurring on the farm, bruising and processing plant damage.

2. The average proportion of birds downgraded each day (TDG) for the four plants varied from 9·6 to 15·7% of production and the largest component was the proportion bruised (3·5 to 8·0% of daily production).

3. The distribution of bruises was similar for the four plants, with breast and leg bruises predominating.

4. There was no correlation between the processing plant line speed and the TDG.

5. No correlation was found between the Performance Indication Factor, a measure of efficiency of food utilisation, and the TDG.

6. Records were available for 77 flocks processed over two consecutive working days. Correlation was low (r = 045) between the TDG for the first and the second day's processing suggesting that farm practices were unlikely to affect the incidence of bruising.

     

Campylobacter succession in broiler chickens

The competitive ability of Campylobacter coli OR12 over C. jejuni OR1 has been examined in experimental broiler chickens following the observation that C. coli replaced an established C. jejuni intestinal colonisation within commercial chicken flocks reared outdoors [El-Shibiny, A., Connerton, P.L., Connerton, I.F., 2005. Enumeration and diversity of campylobacters and bacteriophages isolated during the rearing cycles of free-range and organic chickens. Appl. Environ. Microbiol. 71, 1259-1266]. Co-cultures of C. coli OR12 with C. jejuni OR1, revealed that the two species were able to grow together at similar growth rates in exponential growth phase but if the disparity of the inoculum ratios were >log(10)4 in favour of C. coli OR12, C. jejuni OR1 was observed to prematurely enter decline phase. Chickens were pre-colonised with C. jejuni OR1 at 21-days-old to examine succession in vivo. The birds were inoculated between 2 and 12 days later with C. coli OR12, to determine if the second isolate could efficiently colonise and compete with an established C. jejuni strain. C. coli OR12 were able to co-colonise before replacing C. jejuni OR1 as the dominant species when the birds were more than 27 days of age at the time of administration over a 4-day period. If these criteria were met C. coli OR12 became the dominant isolate otherwise co-colonisation occurred until they were met. C. coli OR12 was also found to displace three alternative C. jejuni strains from pre-colonised chickens challenged with C. coli OR12 at 30 days of age and tested at 40 days. These data raise the possibility of manipulating populations of Campylobacter colonising chickens through competition.     

Swollen-head syndrome in broiler chickens

Swollen-head syndrome is a disease seen in broiler chickens between 4 and 6 weeks of age in Southern Africa. It appears to be caused by a mixed coronavirus and Escherichia coli infection. The coronavirus appears to be of a hitherto unrecorded serotype. The disease is controlled by an attenuated live-virus vaccine and antibacterial medication.     

Salt poisoning in broiler chickens

The clinical signs of salt poisoning in young chickens are thirst, diarrhoea and weakness. When 13 500 broilers are simultaneously affected, the deterioration that occurs in their physical condition and in the litter beneath their feet is dramatic. Two flocks of meat chickens on a small unit in North Otago were affected in this way.     

Feeding dihydroquercetin to broiler chickens

1. A total of 80 male Ross 308 broilers were used in a study to investigate the effect of dietary dihydroquercetin (DHQ) on growth performance variables, gastrointestinal tract (GIT) and immune organ development, glutathione peroxidase (GPx) and haemoglobin in blood, hepatic vitamin E content, dietary N-corrected metabolisable energy (AMEn) and nutrient retention coefficients when fed to broiler chickens from 7 to 35 d of age.

2. Two treatments were used in this study: control (C) and C + 0.5 g/kg extract of Siberian Larch (Larix sibirica) per kg feed, containing 85% DHQ. The diets were fed over 2 feeding phases, a grower phase from 7 to 28 d of age and a finisher phase from 28 to 35 d of age. The birds were reared under the breeder’s recommended conditions.

3. In general, there were no effects of DHQ on growth performance of broiler chickens. However, the results of this experiment showed that there can be changes in the redness colour of the breast meat when DQH is fed. No negative effects of feeding DHQ at 0.5 g/kg diet were observed in this study.

4. Supplementation of poultry diets with DHQ under standard industry-rearing conditions did not improve the performance or any of the studied variables, except an increase of redness index of the breast fillets. Feeding DHQ at different doses and/or under more challenging conditions, e.g. heat stress, may, however, bring positive responses.     

Salt poisoning in broiler chickens

The incident occurred on a small, owner-operated broiler unit that used home-mixed feed. Two flocks of broilers, one aged 6 weeks and one aged 6 days, developed signs of watery diarrhoea, thirst and weakness. Over 3 days the mortality increased considerably and many birds were noticed to show laboured breathing. The majority of dead birds had an excess of clear fluid in the pericardial sac, oedematous lungs and pale swollen kidneys. Cystic dilation of the testes was conspicuous in several birds from the younger flock killed at 12 days of age. This lesion is a specific indication of sodium toxicity in young broilers. Histological lesions were those associated with cardiovascular collapse and hypoxia. Liver levels of sodium chloride were 4 g/kg of wet weight. Broiler feed samples contained more than 7% sodium chloride whereas the nutritional specifications were for 0.4%. The rations had been correctly mixed and the problem was traced to a faulty batch of meatmeal that had been contaminated by salt used for curing hides.     

Application of real-time ultrasound technology to estimate in vivo breast muscle weight of broiler chickens

1. Real-time ultrasound (RTU) is a fast, non-destructive and relatively inexpensive technique to estimate body composition in animals. 2. A total of 835 Hubbard, Ross and Cobb broilers from different flocks were randomly selected, weighed and two RTU measurements were taken from both sides of their breast muscles (BM). Immediately following ultrasonography, broilers were processed and dissected to determine carcase, boneless BM, leg quarter and wing weights. Data were utilised to develop multiple linear regression equations (MLRE) to estimate carcase part weights. 3. Factors such as sex, age or genetic line did not contribute significantly to the accuracy of the models. The measurement in the right side was consistently more efficient than the left for estimating BM weight. 4. The following MLRE was estimated from live body weight (BW) and RTU area images: BM (g) = -94.3476 + 0.1518 * BW (g) + 5.1644 * BM-RTU area (cm2) (R2 = 0.97). 5. Due to the allometric relationships among body parts the following equations were also estimated: Legs (g) = -56.6738 + 0.2846 * BW (g) + 2.1570 * BM-RTU area (cm2) (R2 = 0.98) and Total Meat Cuts (g) = -142.0567 + 0.4638 * BW (g) + 5.1236 * BM-RTU area (cm2) (R2 = 0.99). 6. The results indicated that it was possible to estimate BM and other carcase cut weights with high accuracy from RTU measurements.     

肉鸡低血糖-尖峰死亡综合征

1　概况肉鸡低血糖 -尖峰死亡综合征 ( hyperglycemia-spiking mortality syndrome of broiler chickens,HSMS)是一种主要侵害肉仔鸡的传染病 ,其病原目前尚未确定。 1 0～ 1 8日龄为发病高峰期 [1,9] ,也有报道 42日龄肉鸡发生 [2 ] 。临床表现为突然出现的高死亡率 ( >1 .0 % )至少持续 3～ 5天 ,同时伴有低血糖症。病鸡头部震颤 ,运动失调 ,昏迷 ,失明 ,死亡。有些病鸡可以自然康复 ,但常会出现生长发育不良、矮小和气囊炎[3～ 5,10 ] 。本病自 1 986年美国 Delmarva半岛地区首次报道后[3 ] ,加拿大、南非、马来西亚、欧洲等国家均有本…     

Pharmacokinetics of tylosin in broiler chickens

Biological availability and pharmacokinetic properties of tylosin were determined in broiler chickens after oral (p.o.) and intravenous (i.v.) administration at a dose of 10 mg/kg. The calculated bioavailability--F%, by comparing AUC values--p.o. and AUC--i.v., ranged from 30%-34%. After intravenous injection tylosin was rapidly distributed in the organism, showing elimination half-life (t1/2 beta) values of 0.52 h and distribution volume (Vd) of 0.69 L/kg, at a clearance rate (Cl) of 5.30 +/- 0.59 ml/min/kg. After oral administration, tylosin has a similar distribution volume (Vd = 0.85 L/kg), while the elimination half-life t1/2 beta of 2.07 h was four times bigger than after i.v. administration at Cl = 4.40 +/- 0.27 ml/min/kg. The obtained value tmax = 1.5 h for tylosin after oral administration indicates that using this antibiotic with drinking water in broiler chickens is the method of choice. However, a relatively low value Cmax = 1.2 micrograms/ml after oral administration of tylosin shows that dosing of this antibiotic in broiler chickens should be higher than in other food producing animals.     

Pharmacokinetics of butorphanol in broiler chickens

Butorphanol tartrate (2 mg/kg) was injected intravenously in 18 healthy broiler chickens to study its pharmacokinetics. Plasma samples were analysed by a highly sensitive high-performance liquid chromatography with diode-array detection method and pharmacokinetic parameters were calculated from the mean pooled data. With non-compartmental analysis, the terminal half-life (T(1/2.z)) was 71.3 minutes, clearance was 67.6 ml/minute/kg and the apparent volume of distribution was 6.9 l/kg. The concentration-time curve was also fitted to a two-compartmental model. In this analysis, elimination half-life (T(1/2β)) was 69.3 minutes, clearance was 74.6 ml/minute/kg and volume of distribution at steady state was 5.6 l/kg. The micro rate constants k(21), k(12) and k(10) were 0.034, 0.050 and 0.029, respectively. Butorphanol was well distributed in the chickens with rapid clearance. It remained above the minimum effective concentration for analgesia in mammals for approximately two hours in the chickens.     

Development of immunocompetence of broiler chickens

Subpopulations of T-cells, B-cells, macrophages and ellipsoid-associated reticular cells (EARC) could be demonstrated by immunohistochemical staining early in the development of chicken spleen. However, the typical structures of the spleen, such as the peri-arteriolar lymphoid sheath (PALS) and the ellipsoids with their surrounding ring of macrophages, were only formed around embryonic day (ED) 20. These structures and especially the B-cell compartment, i.e., the peri-ellipsoid lymphoid sheath (PELS) gradually matured during the first week posthatch.

Therefore, we analysed at what age broiler chickens could generate a humoral response against the thymus-dependent antigen bovine serum albumin (BSA). Chickens were immunised in ovo (ED16 and ED18) and at 1, 7 and 12 days of age and subsequent BSA-specific immunoglobulin (Ig) M and IgG responses were measured up to 10 days postimmunisation (DPI). No major differences were observed in the relative growth rates, while hatchability was only slightly reduced. Only in chicks immunised on 12 days of age, IgM and IgG responses were high with a normal kinetic pattern. In chicks immunised on 7 days of age, responses were just detectable, but they were absent in chicks immunised in ovo and on the day of hatching (Day 1).

In a subsequent experiment, 1-, 7- and 12-day-old chicks were BSA-immunised and Ig responses were measured for a longer period up to the age of 28 days. The IgG response of chicks immunised at 1 day of age was lower and occurred later (from 28 DPI) than the response of chicks immunised at 7 and 14 days of age (from 14 DPI). It was not increased by a booster immunisation on 29 days of age, in contrast to the response of chicks immunised at 7 and 14 days of age. These findings indicate that vaccination at 1 day of age does not activate the B-cell response resulting in antibody production and support the idea that the immune function of the late embryonic and neonatal chickens is not entirely developed due to the incomplete structural organisation of their secondary immune organs.     

Differential expression of genes implicated in liver lipid metabolism in broiler chickens differing in weight

ABSTRACT

1. Lipid parameters and expression of ACACA, APOA1, CPT1A, FASN, FOXO1, LIPG, PPARα and SIRT1 genes involved in lipid metabolism were investigated in two groups of high (HW) and low (LW) weight broilers from the same strain.

2. Blood cholesterol and liver triglyceride levels were significantly increased in HW chickens compared to LW broilers, while other parameters, i.e. blood triglyceride, blood HDL/LDL, liver cholesterol and total liver fat showed no significant changes in either group.

3. The relative expression of ACACA, APOA1 and CPT1A genes was significantly lower in the liver tissues of HW broilers than in the LW group. The mRNA levels of these three genes showed a significant negative correlation with abdominal fat deposition and live weight of broilers. However, relative expression of FASN, FOXO1, LIPG, PPARα and SIRT1 hepatic genes did not differ among broilers.

4. It was concluded that, of eight hepatic genes implicated in lipid metabolism, only the expression of three (ACACA, APOA1 and CPT1A) were significant for fat and leanness within the same strain of chicken. Since reducing body fat is a major goal in the broiler industry, these data can provide fresh insight into the molecular processes underlying the regulation of fat deposition in broilers.     

Campylobacter jejuni infection in broiler chickens

Day-old, straight-run broiler chickens were procured from a hatchery located in the Pacific Northwest. The chickens were subdivided individually into nine groups of 20 chickens. The chickens were tagged, housed in isolation chambers on wire, fed commercial broiler feed, and given water ad libitum. Three isolates of Campylobacter jejuni of poultry origin and one of human origin were tested in this study. Various C. jejuni cultures were inoculated into 9-day-old chickens by crop gavage. Four groups of 20 chickens were inoculated at a dose level of 0.5 ml of 1 x 10(2) colony-forming units (CFU)/ml. The other four groups were inoculated with 0.5 ml of 1 X 10(4) CFU/ml. One group of 20 chickens was kept as an uninoculated control group. Four randomly selected chickens from each of the inoculated and uninoculated groups were necropsied at 5, 12, and 19 days postinoculation (DPI). The C. jejuni was cultured and enumerated from a composite of the upper and midintestine and the cecum. Body weights of all chicken groups at 7 days of age and at 5, 12, and 19 DPI were measured and statistically analyzed. No significant differences were present in the mean body weights (MBWs) of 7-day-old, 5 DPI, and 12 DPI male and female broiler chickens inoculated with C. jejuni at both dose levels compared with uninoculated controls. Differences in MBWs of the male and female broilers at 19 DPI were observed in some of the groups. Results of the C. jejuni culture enumeration mean (CEM) of composite intestine samples at 5 DPI from all inoculated chicken groups, irrespective of the dose level, ranged from (2.5 +/- 5.0) x 10(2) to (2.8 +/- 4.8) x 10(5) CFU/g (mean +/- SD). Results of cecum C. jejuni CEM at 5 DPI inoculated at both dose levels ranged from (2.5 +/- 5.0) x 10(6) to (1 +/- 0.0) x 10(7) CFU/g in all treatment groups irrespective of the dose level. CEM results from the composite intestine samples at 12 and 19 DPI increased by 1 log unit, or sometimes more. Results of cecum C. jejuni CEM at 5 DPI inoculated at both dose levels ranged from (2.5 +/- 5.0) x 10(6) to (1 +/- 0.0) x 10(7) CFU/g in all treatment groups irrespective of the dose level. Increases of 2-5 log units in C. jejuni CEM was present in chicken groups inoculated with 1 X 10(2) CFU of C. jejuni, and a 2- to 3-log increase was present in groups inoculated with a higher dose level of C. jejuni at 12 DPI. The results of C. jejuni CEM from cecal samples at 19 DPI were similar to chicken groups at 12 DPI. Campylobacterjejuni was not isolated from the uninoculated control chickens at 5, 12, and 19 DPI. Clinical signs of illness or gross pathologic lesions were not present in any of the chicken groups during this study. No lesions were present on histopathologic evaluations in C. jejuni-inoculated chickens or uninoculated control chickens.