Musculo-skeletal lesions in adult male broiler breeder fowls and their relationships with body weight and fertility at 60 weeks of age

1. Males from three broiler breeder experiments were examined to determine the incidence of musculo-skeletal lesions (destructive cartilage loss, dyschondroplasia and its sequelae, ruptured tendons and ligaments) in birds culled for low fertility and in males surviving to the end of the breeding period. Relationships with body weight and fertility were studied. 2. The incidence of musculo-skeletal lesions in males culled for low fertility was high. 3. In two experiments, high body weights at termination of the breeding period were associated with a raised incidence of musculo-skeletal lesions and lowered fertility. 4. The results support the hypothesis that lack of control of male body weight gain per se is an important cause of declining fertility with age in broiler breeder flocks. There was no evidence that males were obese.     

Prevalence of antibodies against Ornithobacterium rhinotracheale in broilers and breeders in Southern Brazil

In this investigation, we determined the prevalence of the Ornithobacerium rhinotracheale (ORT) infection in broilers and broiler breeders in southern Brazil. We also correlated the presence of antibodies in broilers with performance. Sera from 1550 broilers from 50 flocks were collected during the slaughter time in nine companies with federal veterinary inspection of the state of Rio Grande do Sul. Sera from 480 meat-type breeders of 40 flocks from 14 companies in southern Brazil were also analyzed by enzyme-linked immunosorbent assay, and the prevalence of antibodies was determined. The prevalence of ORT antibodies in broiler flocks was 63.83%, but in each individual flock only 6.52% of the birds were positive. The prevalence in broiler breeder flocks was 100.00%, and in each individual flock 94.62% of the birds were positive. There was a positive correlation between the presence of antibodies to ORT and decreased body weight in broilers. There was no significant correlation between presence of antibodies to ORT and age, lineage, efficiency index, feed conversion, and mortality. There was a positive correlation between the presence of respiratory signs and antibodies to ORT, although the reverse correlation was not significant. These results confirm that ORT is present and widespread in broilers and broiler breeders in southern Brazil.     

Flock data reported from a poultry slaughter house (broilers)]

Six broiler flocks have been compared with regard to the occurrence of attributes according to an examination protocol. Approved birds were scrutinized per random sample, condemned birds altogether. Parameters of examination were body weight occurring attributes (computed single and cumulated) count of dead and condemned birds in fattening period, transport and on slaughter line as well. Each flock was conspicuous in one or another respect. The graduation of the flocks was possible using the factors losses in the fattening period count of condemnation losses in the total production line coefficient of variation of weights attributes occurring in the meat inspection cumulated count of all attributes leading to condemnation. Results demonstrate, that graduation of different flocks by means of quantitative measurements is possible.     

Detection of Campylobacter jejuni strains in the water lines of a commercial broiler house and their relationship to the strains that colonized the chickens

Campylobacter jejuni is frequently present in the intestinal tract of commercial broiler chickens, and their drinking water has been proposed to be an initial source of bacteria for newly hatched chicks. We studied three sequential commercial broiler flocks raised in a house from which we had cultured C. jejuni from the nipple waters prior to placement of the first flock. Campylobacter cells were detected by immunofluorescence in the biofilm of the drinking nipples during the weeks when the flock was colonized with C. jejuni but not during weeks when the birds were negative. Campylobacter jejuni was isolated from the drinking water during the growth of the first flock and was present in the birds from all three flocks. Randomly amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) typing with primer OPA11 indicated that seven distinct strains were present within the broiler house. One strain found in drinking water was similar to a strain found in birds in the second flock; however, RAPD-PCR with primer HLW85 showed that the strains were not identical. These results suggest that although the watering system is a potential source of C. jejuni in broiler flocks, the waterborne strain in this study was not detected in the birds.     

Economic effects of clinical chicken anemia agent infection on profitable broiler production.

An outbreak of anemia dermatitis syndrome caused by chicken anemia agent (CAA) occurred in 15 broiler flocks. An average of 29% of chickens in these flocks were derived from a common breeder flock. The breeder flock had no antibody to CAA at 20 weeks of age but had seroconverted by 31 weeks. Diseased broiler flocks were derived from eggs laid by the breeder flock between 25 and 30 weeks of age. CAA infection in the breeder flock was subclinical, with no apparent effects on mortality or performance. A strategic program of therapeutic and/or prophylactic antibiotic therapy was begun in affected broiler flocks as soon as the disease was diagnosed. Nevertheless, when the cost of therapy was taken into account, affected broiler flocks had a net income 17.3% to 19.6% lower than normal flocks. Average bird weights were 3.3% to 3.5% lower in affected flocks than in unaffected flocks, and affected flocks had a significantly greater proportion of lighter birds. Average mortality in affected flocks was 2.0% to 2.3% higher than in normal flocks, with peak mortality occurring in the third week of life. There was no apparent effect on feed-conversion ratio.     

Sources of Salmonellae in broiler chickens in Ontario.

Sources of Salmonellae infecting broiler chicken flocks in Ontario were investigated from July, 1975 to April, 1976. Three broiler flocks were investigated on each of four farms which received chicks from a common hatchery. Samples of feed and new litter were preenriched in nonselective broth subcultured to Salmonella-selective enrichment broth and plated on Salmonella-selective differential agar.Samples of used litter, water, culled chicks, insects, mice, wild birds and environmental swabs were not cultured initially in the nonselective broth. Fecal samples from principal and occasional flock attendants were examined for Samonellae. Salmonella infection, as judged by contaminated flock litter was detected in six flocks on two of the farms while the flocks on the other farms remained negative. Salmonellae were isolated from 23 of 412 feed samples (nine serotypes), six of 35 new wood shaving samples (four serotypes), one of 29 pools of culled chick viscera (one serotype) and 44 of 267 used litter samples (14 serotypes). These results indicate that broiler chicken flocks were infected with diverse Salmonellae introduced in day old chicks, pelleted feeds, wood shavings and residual contamination from the preceding flock.     

Risk factors associated with hydropericardium syndrome in broiler flocks.

A prospective study was undertaken to identify the epidemiological factors associated with the development and spread of the hydropericardium syndrome in broiler flocks. Data were collected between July 1989 and April 1990 from 131 flocks in 105 broiler production units pertaining to their demography, management practices, prophylactic procedures and concurrent diseases. The incidence rate of the syndrome in the whole population was 46.6 per cent. There were significant associations between the incidence in a flock and visits by a poultry vaccination crew (P = 0.014), the number of flocks raised (P = 0.004) and the source of light and heat (P = 0.007). Flocks that had one or more visits by a poultry crew were 15 times more likely to be affected by the syndrome than flocks that had no such visits. Premises where one flock was raised were nearly three times more likely to be affected than premises where two flocks were raised, and the use of electricity as a source of light and heat entailed a much lower risk of hydropericardium syndrome than kerosene oil.     

Prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in broiler chicken and turkey flocks slaughtered in Quebec, Canada

We conducted an observational study to estimate prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in poultry. Eighty-one broiler chicken and 59 turkey flocks selected among flocks slaughtered in the province of Quebec, Canada, were included in the study. Flock status was evaluated by culturing pooled caecal contents from about 30 birds per flock. Exposure to potential risk factors was evaluated with a questionnaire. Odds ratios were computed using multivariable logistic regression.

The prevalence of Salmonella-positive flocks was 50% (95% CI: 37, 64) for chickens and 54% (95% CI: 39, 70) for turkeys, respectively. Odds of Salmonella colonization were 2.6 times greater for chicken flocks which failed to lock the chicken house permanently. In turkeys, odds of Salmonella colonization were 4.8–7.7 times greater for flocks which failed to be raised by ≤2 producers with no other visitors allowed onto the premises, or origin from a hatchery.

The prevalence of Campylobacter-positive flocks was 35% (95% CI: 22, 49) for chickens and 46% (95% CI: 30, 62) for turkeys. Odds of colonization were 4.1 times higher for chicken flocks raised on farms with professional rodent control and 5.2 times higher for flocks with manure heap >200 m from the poultry house, and also increased with the number of birds raised per year on the farm and with the age at slaughter. For turkeys, odds of Campylobacter flock colonization were 3.2 times greater in flocks having a manure heap at ≤200 m from poultry house and 4.2 times greater in flocks drinking unchlorinated water.     

Effect of age of maternal flock and strain on the incidence of tibial dyschondroplasia in growing chicks.

Two experiments were conducted to study the effects of age of the maternal flock (27 vs. 57 weeks of age at time the eggs were set) and strain of broiler chicks (Cobb 500, Ross, Arbor Acres, and Avian) on the incidence of tibial dyschondroplasia (TD) in broiler cockerels grown to 3 weeks of age. The chicks were fed a corn/soybean meal-based diet containing 3145 kcal metabolizable energy corrected for nitrogen retention (MEn)/kg, 24% protein, and 0.50% available phosphorus. Each treatment was replicated four times with eight chicks per pen. In Expt. 1, chicks from the old parent flock had significantly higher body weights (P < or = 0.05) than those from the young parent flock. There were no significant differences in feed efficiency or incidence of TD. In Expt. 2, body weights, feed efficiency, and TD were unaffected by strain.     

Haematological characteristics predicting susceptibility for ascites. 2. High haematocrit values in juvenile chickens

1. Male broilers of two different genetic stocks, a pure broiler sire line (A) and commercially available Ross broilers (B), were used to study the effect of differences in haematocrit values in 12-d-old chickens on the development of ascitic symptoms. Body weight gain (BWG), feed intake (FI) and feed conversion ratio (FRC) were measured from 2 to 5 weeks of age. Mortality was recorded from 2 to 6 weeks. The birds were kept at a low ambient temperature to stimulate the incidence of ascites. 2. From each stock 32 birds with the highest (High Ht) and 32 birds with the lowest (Low Ht) haematocrit values in venous blood were selected at 12 d of age for an examination on susceptibility for the ascites syndrome at 5 weeks. 3. At 2 weeks 448 birds per stock (including High Ht and Low Ht birds) were allotted to 32 floor pens (1 High Ht and 1 Low Ht in each pen). Venous blood samples were taken weekly in High Ht and Low Ht birds for haematocrit measurements and at week 5 also thyroid hormone (T3, T4) concentrations in plasma were measured. At 5 weeks all High Ht and Low Ht birds were examined post-mortem and arterial pressure index, heart weight, lung weight and liver weight (all relative to body weight) were recorded. High values for arterial pressure index, relative heart and liver weights and low values for relative lung weights and plasma thyroid hormone were considered to be indicators for ascites susceptibility. 4. Stock A, with the highest ascites mortality, had lower values for BWG and FCR than stock B. Throughout, a clear difference in Ht values between High Ht and Low Ht birds was maintained. No significant effects of 12-d haematocrit values were found on the incidence of ascitic symptoms until week 5. High Ht values tended to correlate with low relative lung weights and low plasma T3 concentrations in High Ht birds. 5. Within the groups of selected birds, there was an effect of stock on ascitic symptoms (arterial pressure index, relative heart weight and T3 values) at week 5. This is consistent with a higher ascites mortality in flock A than in flock B, over the whole period up to 6 weeks. Until 4 weeks both A and B were similar with respect to mean Ht values of High Ht and Low Ht groups. After 4 weeks Ht values were very high in the High Ht birds of stock A, possibly as a result of the susceptibility for ascites of stock A. There was a significant interaction between stock and Ht values on the ascites-related variable arterial pressure index. Only in stock A was high arterial pressure at 5 weeks related to high Ht values at d 12. 6. Overall it was concluded that a high Ht in blood of juvenile chickens has limited practical value in predicting incidence of ascites at 5 weeks of age.     

The occurrence of a reovirus variant in a German broiler flock

Broilers deriving from a parent flock, which had been effected in the 6th. month of hatching egg production, show arthritis beginning with the 12th day of life. The tarso-metatarsal joint has been affected. Birds show stunting. Body weights at slaughter and feed conversion of the affected flocks were reduced. The percentage of condemned birds before slaughter was highly increase and came up to 3-5%. Chickens of other breeder flocks, which were reared with the diseased birds, showed viral arthritis at an age of 18-20th day of life. The boilers derived from parent flocks which had been vaccinated twice during the with a 1133 reo live vaccine and before laying with an oil based vaccine of the antigen type WVU. A reovirus has been isolated (isolate K 171/87), which caused viral arthritis in 1133-immune day old chicks after parenteral and oral application. Infection of these chickens with the pathogenic reovirus of the antigen type 1133 didn't cause a disease. Also by serological examinations it was shown, that the reo-isolate K 171/87 possesses a different antigenicity. The kind of occurrence indicates, that this reovirus infection has been transmitted vertically from one parent flock and it spread laterally to chickens of other parent flocks in broiler farms.     

Reduced incidence of Clostridium perfringens-associated lesions and improved performance in broiler chickens treated with normal intestinal bacteria from adult fowl

The dosing of young chicks with cultures of normal gut flora has been termed "competitive exclusion" (CE). This study was undertaken to examine, under field conditions, the effect of CE treatment on counts of intestinal Clostridium perfringens (CP) and on the occurrence of CP-associated disease in broiler chickens. A farm having recurrent CP-associated health problems was selected as study site. The study comprised four broiler houses, with one treated and one untreated flock per house. Treated birds were sprayed with the CE product Broilact upon arrival at the farm. All flocks were offered feed containing the ionophorous anticoccidial agent narasin. The feed did not contain growth promoters. Treatment was associated with positive but statistically nonsignificant effects on gut health. Delayed intestinal proliferation of CP and delayed appearance of CP-associated gut lesions were found in CE-treated flocks. This delay was associated with improved production performance at slaughter.     

Incidence of white striping under commercial conditions in medium and heavy broiler chickens in Italy

Several types of muscle abnormalities are present in the poultry industry as a result of genetic selection, leading to decreased quality of meat and consequent economic loss. The appearance of thin (moderate) to thick (severe) white striping (WS) striations parallel to muscle fibers on the surface of broiler breast fillets is one of the most troubling issues in the poultry industry. White striping also has unfavorable implications on visual acceptance, nutritional value, and processing traits of breast meat. The aim of this survey was to assess the influence of market class (medium and heavy birds) and genotype (standard- and high-breast yield hybrids) on the incidence of WS in broiler chickens raised under commercial conditions in Italy. The incidence of WS for both medium and heavy broilers was high (43.0%), with 6.2% of samples considered severe. Heavy flocks had significantly higher percentages of both moderate (46.9 vs. 25.8%;P ≤ 0.001) and severe (9.5 vs. 2.7%;P ≤ 0.001) WS than medium flocks. Considering the effect of genotype, high-breast yield hybrids exhibited a higher incidence of both moderate (40.2 vs. 33.2%;P ≤ 0.001) and severe WS (7.2 vs. 5.0%;P ≤ 0.001) compared with standard-breast yield birds. In addition, within the medium class, the occurrence of WS reached higher levels in flocks of males. The heavy class consisted of male flocks separated into 2 slaughter weight categories. Birds that reached higher slaughtering weights (3.8–4.2 kg) exhibited higher incidence of WS than flocks slaughtered at lower weights (3.0–3.8 kg) at a similar age. In conclusion, the main broiler genotypes used for commercial production were affected by a high rate of WS; hybrids selected for higher breast yields were more prone to the WS abnormality. In addition, severe cases of WS are even more prevalent at higher slaughter age and weight, although reduced growth rate is associated with a lower incidence and severity of WS.     

Incidence of Salmonella Contamination in Broiler Chickens in Saskatchewan

The incidence of Salmonella contamination in ten Saskatchewan broiler flocks varying in size from 6 200 to 14 000 was investigated from February, 1977 to April, 1979. Prior to the initial chick placement, brooding equipment, feed, water and fresh litter samples were found to be free of Salmonellae. Samples obtained from the clean and disinfected processing plant equipment before the commencement of daily operation were negative except the isolation for Salmonella anatum from the fingers of the defeathering machine in flock 4. There was no evidence of Salmonella contamination in flocks 5, 6, 8 and 10. The incidence of Salmonella was lower when cloacal swabs were taken from day old chicks fasted for 48 hours than for the same groups of chicks when carcasses were blended in nutrient broth (flocks 7 and 9). The blending of such chicks appears to be a more critical test. The serotypes isolated from eviscerated birds were the same as those isolated from used litter samples. Salmonella saintpaul was isolated from a water sample at 53 days in flock 1 and the same serotype was recovered from the intestinal contents and skin of eviscerated birds. Salmonella typhimurium was recovered from the eviscerated birds and neck samples in flock 3. In flock 4, S. saintpaul and S. anatum were isolated from 13% of the eviscerated birds sampled. Salmonella thompson, Salmonella agona and Salmonella heidelberg were recovered from 61%, 5% and 1%, respectively, of the processed carcasses sampled in flock 7.     

Cellulitis in broiler chickens: a one-year retrospective study in four Québec abattoirs

A 1-yr retrospective study was undertaken to verify whether the prevalence of cellulitis in broiler chicken flocks was associated 1) with sex and average body weight controlling for the time of year and 2) with some other condemnation causes such as air-sacculitis, ascites, cyanosis, emaciation, valgus varus deformity, peritonitis, and total condemnation rate controlling for sex, average body weight, and time of year. Data were collected from four Québec abattoirs between October 1992 and September 1993. Data from 2452 unisex male and female broiler flocks were compiled and analyzed with univariate and multivariate models. The prevalence of cellulitis among flocks was 42.2 per 10,000 birds slaughtered. Cellulitis was associated with sex and increased with time of year (P < 0.0001). The prevalence was higher in male (mean +/- SD, 50.7+/-24.3; median, 31.8) than in female flocks (mean +/- SD, 34.2+/-15.6; median, 20.0) but showed no relationship with average body weight. Associations between condemnation causes and cellulitis were relatively weak; increases in the prevalence of cellulitis correlated with increases in total condemnation rate (r2 = 0.19), ascites (r2 = 0.09), airsacculitis (r2 = 0.0), cyanosis (r2 = 0.04), peritonitis (r2 = 0.03), emaciation (r2 = 0.02), and valgus varus deformity (r2 = 0.02). These results suggest that flock sex is a potential correlate of cellulitis prevalence in broiler chickens. Associations between the prevalence of cellulitis and other diseases observed at the abattoir were not very strong. However, it appears here that general disease status of Québec broiler flocks is a better indicator of cellulitis occurrence than the main diseases considered individually.     

A longitudinal study of campylobacter infection of broiler flocks in Great Britain

One hundred flocks associated with five integrated poultry companies were monitored for one production cycle to investigate risk factors for campylobacter infection of poultry broiler flocks. Bacteriological samples were collected from one house of birds on each site at weekly intervals from 3 to 4 weeks of age until the birds were infected with campylobacter or the flock was depopulated (whichever was sooner). Environmental samples were obtained from 20 houses after cleansing and disinfection of the site before chick arrival. Conventional methods were used for the isolation of campylobacter. Questionnaires were used to collect information on potential risk factors for campylobacter infection. Discrete-time survival analysis was used to assess the influence of various exposures on the age at which the flock was infected with campylobacter.More than 40% of flocks were infected with campylobacter by the time the chicks were 4 weeks old and >90% by 7 weeks. Infection spread rapidly to most birds in a flock. Infection was not predictable by campylobacter status of the last flock reared on the site. (However, because most flocks were infected, the power to detect such an association was poor.) There was no evidence of environmental survival of campylobacters in broiler houses after adequate cleansing and disinfection. The most important predictors of protection from campylobacter were related to effective hygiene barriers (such as housing birds in buildings in a good state of repair, appropriate usage of disinfectant boot dips and a high standard of cleansing and disinfection of the drinking-water equipment). There was no evidence that rodents were a source of infection (but most sites operated effective vermin-control programmes).     

Performance comparison between the use and nonuse of an enteric health medication program across five consecutive commercial broiler flocks

A study was conducted to examine broiler performance and carcass yield across 5 consecutive commercial broiler flocks after the removal of roxarsone (ROX) and growth-promoting antibiotics (GPA) from the feed. Over a 1-yr period, approximately 552,000 broilers were reared in 4 solid-walled, tunnel-ventilated houses, divided into 2 paired-house facilities, and were assigned 1 of 2 dietary treatments. The treated group received basal diets containing salinomycin, ROX, and GPA, whereas the control group received the same diets without ROX and GPA. Average BW were recorded for 200 sample birds/treatment per flock at 18, 35, and 48 d of age. Average BW, feed conversion, adjusted feed conversion, livability, and condemnation were calculated at the completion of each flock. Coccidiosis lesion scores of 10 birds per treatment were recorded at 14, 21, 28, 35, and 42 d of age. Before birds were transferred to a commercial processing plant, 280 birds/flock were randomly selected, weighed, and tagged for carcass yield analysis. Livability was significantly negatively affected by the removal of ROX and GPA. Coccidiosis lesion scores were not affected by the treatments. Tender yields showed significant improvement, whereas all other cuts were not affected by removal of ROX and GPA.     

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.     

Correlation of enzyme-linked immunosorbent assay titers with protection against infectious bursal disease virus.

We examined the utility of baculovirus-expressed infectious bursal disease virus (IBDV) proteins to act as antigens in the enzyme-linked immunosorbent assay (ELISA). The three IBDV protein antigens tested included 1) a truncated VP2, 2) whole VP2, and 3) the polyprotein products VP2, VP3, and VP4. Serum samples from 2-wk-old commercially reared broilers were collected and tested in the three ELISAs. Serum samples were obtained from 34 different commercial broiler flocks. An average of 14 serum samples (range = 11-17) were tested for each flock. The ELISA results were compared with the percentage of protection of these birds following challenge with IBDV. Fifty 2-wk-old chicks from each of the 34 broiler flocks were challenged with STC classic virus or Del-E variant virus. At 7 days postchallenge, the bursa from each of the birds was removed and bursa/body weights were recorded. Percentage of protection was determined by the number of birds in each challenge group that had normal relative bursal weights compared with unchallenged controls. No evidence was found of a relationship between ELISA data generated with the polyprotein antigen (VP2, VP3, VP4) and percentage of protection observed in the STC and Del-E challenged birds. A significant relationship was found between ELISA data and percentage of protection to STC and Del-E when the truncated VP2 or whole VP2 antigens were used in the ELISA. The results of this study indicate that predicting the percentage of protection against classic or variant IBDV strains in broilers from vaccinated breeder flocks can be improved when VP2 is used as the only antigen in the ELISA.     

The influence of phytase,pre-pellet cracked maize and dietary crude protein level on broiler performance via response surface methodology

Background: The reduction of crude protein levels in diets for broiler chickens may generate economic,environmental and flock welfare and health benefits; however, performance is usually compromised. Whole grain feeding and phytase may improve the utilization of reduced crude protein diets.Results: The effects of pre-pellet cracked maize(0, 15% and 30%) and phytase(0, 750 and 1500 FTU/kg) in isoenergetic maize-soy diets with three levels of crude protein(22%, 19.5% and 17%) were evaluated via a BoxBehnken response surface design. Each of 13 dietary treatments were offered to 6 replicate cages(6 birds/cage) of male Ross 308 broiler chicks from 7 to 28 d post-hatch. Model prediction and response surface plots were generated from experimental data via polynomial regression in R and only significant coefficients were included and discussed in the predicted models. Weight gain, feed intake and FCR were all influenced by pre-pellet cracked maize, phytase and crude protein level, where crude protein level had the greatest influence. Consequently, the reduction from 22% to 17% dietary crude protein in non-supplemented diets reduced weight gain, feed intake,relative gizzard weight, relative gizzard content and relative pancreas weight but improved FCR. However, the inclusion of 30% cracked maize to 17% crude protein diets restored gizzard weight and 1500 FTU phytase inclusion to 17% crude protein diets increased relative gizzard contents and pancreas weights. Cracked maize and phytase inclusion in tandem to 17% crude protein diets increased weight gain, feed intake and FCR; however, this FCR was still more efficient than broilers offered the non-supplemented 22% crude protein diet. Broilers offered the prepellet cracked maize and phytase inclusions reduced AME in 22% crude protein diets but improved AME by 2.92 MJ(14.16 versus 11.24 MJ; P 0.001) in diets containing 17% crude protein. Ileal N digestibility was greater in broilers offered diets with 17% crude protein than those offered the 22% crude protein diet; irrespective of phytase and pre-pellet cracked maize.Conclusion: Pre-pellet cracked maize and phytase inclusions will improve the performance of broilers offered reduced crude protein diets.