Effect of pelleted feed on the incidence of ascites in broilers reared at low altitudes

A study was conducted to investigate whether the use of pelleted feeds might influence the incidence of ascites in broilers reared at low altitudes (730 meters above sea level). In two trials carried out under commercial conditions, broilers were fed practical-type rations from 1 day to 7 weeks of age, in either mash or pellet form. In both trials, low incidences of ascites (less than 5%) were recorded for broilers receiving feed as pellets. No cases of the syndrome were observed in birds fed mash, either in the field or at the processing plant. These data suggest that the positive relationship between pelleted feeds and incidence of ascites observed at high altitudes also exists at lower elevations.     

Growth and behaviour of chicks fed on pellets or mash

Newly hatched hybrid and Brown Leghorn chicks were fed on diets in either pellet or mash form and growth and feeding behaviour were studied. The mash was made by re‐grinding the pellets. All chicks fed on pellets were heavier after 40 d, but had eaten no more than those fed on mash. The apparent digestibilities of pellets and mash were about the same in the hybrid chicks but was greater for mash than pellets with the Leghorn birds. All chicks fed on mash spent more time feeding than those fed on pellets, but the times spent on drinking and resting were similar with both food forms. Chicks which were given a choice of food form consistently preferred mash to pellets. It is concluded that pelleted food was converted more efficiently than mash mainly because chicks spent less time feeding on pellets and so expended less energy, and in the case of the Leghorns there may have been improved digestibility when the food was pelleted.     

Interaction between ascites susceptibility and CO(2) during the second half of incubation of two broiler lines: the effect on post-hatch development and ascites mortality

1. The aim of this study was to investigate if genetic predisposition to ascites interacts with changed incubation conditions, and how this might affect the post-hatch performance and ascites susceptibility. 2. An ascites sensitive (A) and resistant (E) broiler line were incubated under standard or high CO(2) conditions (up to 4%) from embryonic d 10 onwards. After hatch, chicks were exposed to cold from the 15th day of the rearing period to increase the incidence of ascites. 3. The A line had a higher post-hatch body weight from week three, higher blood pCO(2) from d 21, higher haematocrit at d 35 and d 42, and higher plasma corticosterone concentration from d 21 onwards, compared with the E line, regardless of incubation conditions, supporting the given selection criteria. Ascites mortality did not, however, differ between lines. 4. Incubation under high CO(2) conditions during the second half of incubation increased the ascites mortality, decreased body weight from week 4 onwards, affected venous blood pCO(2), decreased blood pO(2) from d 31, increased haematocrit at d 35 and d 42, and lowered the thyroxine and triiodothyronine concentrations at most sampling days. These effects were observed in both lines. The results suggested a metabolic programming of CO(2) incubated chickens which affected ascites susceptibility.     

Effect of foraging material and food form on feather pecking in laying hens

1. The aim was to test whether provision of foraging material and food form influence feather pecking and feather damage in laying hens. 2. From week 19 of age, 16 groups of 11 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without access to long-cut straw as foraging material and fed on either mash or pellets. 3. Foraging behaviour was increased in hens with access to straw and time spent feeding was increased in hens fed on mash. In addition, hens fed on mash had longer feeding bouts and higher rates of pecking at the food during feeding than hens fed on pellets. 4. There were interaction effects of foraging material and food form on both feather pecking and feather damage. High rates of feather pecking and pronounced feather damage were only found in hens housed without access to straw and fed on pellets. In groups characterised by high rates of feather pecking the hens also showed more severe forms of this behaviour. 5. Differences in the time budgets of hens kept in different housing conditions suggested that birds fed on mash used the food not only for feeding but also as a substrate for foraging behaviour. 6. In order to avoid problems with feather pecking it is recommended that laying hens are provided with foraging material and fed on mash.     

患腹水综合征的肉仔鸡甲状腺素和器官相对重量变化的研究

240只1日龄雄性Cobb肉仔鸡随机地分为24组,每组10只。1~16组饲喂颗粒饲料,在4~7周龄时实施低温处理(13℃),来诱导腹水综合征(AS)的发生;17~20组为饲喂颗粒饲料的常温对照组;21~24组为饲喂粉料的常温对照组。结果表明,低温诱导的AS的发病率为33.89%,死亡率为19%。低温处理可使肉仔鸡体重及血清中甲状腺素(T4)浓度明显下降(P<0.05),而使肉仔鸡心脏的相对重量和血清中三碘甲腺原氨酸(T3)浓度明显上升(P<0.05)。患AS鸡的体重明显降低(P<0.05),心脏、肺、右心室及肝的重量占活体重的百分比明显升高,血细胞压积上升。由此可知,血清T3浓度的增高是腹水症发病的诱导信号,而T3和T4浓度的下降是腹水症的发生信号。     

Effect of choice feeding on the performance of broilers

1. Male broilers from 21 to 56 d of age were fed their diet either mixed as pellets or mash, or as separate ingredients presented on a free‐choice basis, to determine whether feeding method affected growth, carcase composition or profitability to 56 d of age.

2. The 12 treatments were: 2 completely balanced diets fed as mash or pellets, 8 choice fed diets containing maize or sorghum as the energy source (whole or mash) and protein concentrate (pellets or mash) and 2 unbalanced mixed mash diets containing 50% grain (maize or sorghum) plus 50% protein concentrate.

3. For the choice treatments, one food, grain (maize or sorghum) or protein concentrate (mash or pellets), was placed in each feeder. Broilers fed the complete pelleted or mash diet received the diet in both feeders. Food consumption was recorded weekly. Broilers were weighed at 42 and 56 d of age.

4. There were no significant differences between treatments and the pelleted control diet with regard to body weight, food consumed, food efficiency, carcase ash, dressing percentage and mortality.

5. Choice fed broilers receiving the energy source as whole grains had larger gizzards while the higher protein diets (50/50) resulted in a higher carcase moisture and protein but lower carcase fat than the broilers fed the pelleted control diet.

6. The main advantage of choice feeding appears to be the economical savings of feeding whole grains as the energy source.     

Application of an early skip-a-day feed restriction on physiological parameters, carcass traits and development of ascites in male broilers reared under regular or cold temperatures at high altitude

The present study was conducted to evaluate the effects of a skip‐a‐day feed removal early in life on physiological parameters and ascites occurrence in broilers reared at a high altitude (2100 m above sealevel) under regular or cold temperatures. Three hundred 1‐day‐old male broilers were divided into two equal groups. One group was placed in an enclosure with standard thermal management. The other group treated for the induction of ascites was raised under cold temperature conditions. In each enclosure, birds were randomly assigned to one of two treatment groups (three replicate floor pens of 25 chicks per treatment group): (i) a control was fed a standard starter and grower diet according to the National Research Council; or (ii) a skip‐a‐day feed removal, which was similar to the control except for 24 h fasting intervals at 9, 11 and 13 days of age. Results indicate that live bodyweight following the feed removal at up to 42 days of age was significantly different between the control and skip‐a‐day restricted birds (P < 0.01). Skip‐a‐day feed removal resulted in decreased weight gain (P = 0.005) but did not influence feed conversion ratio. The heterophil : lymphocyte ratio was numerically higher for the cold environment and increased when birds were exposed to fasting, but these differences were not significant. Hematocrit was significantly higher (P = 0.0001) in broilers raised in cold conditions whereas it was not influenced by feed restriction. Circulatory thyroid hormone concentrations were not influenced by the feed restriction program under both environments. Birds subjected to cold had significantly lower (P = 0.0023) carcass yield compared to those reared at normal temperature. Breast yield and abdominal fat deposition were not influenced by cold or feed restriction. A reduction in mortality from ascites was noted in broilers who experienced early skip‐a‐day feed removal under both environmental conditions.     

Egg production responses of hens given a complete mash or unground grain together with concentrate pellets

Thirty‐three light hybrids aged 11 months were caged individually and fed for S weeks according to three regimes, viz. A, a conventional mash ad libitum; B, a mixture of whole wheat, barley and kibbled maize ad libitum in the morning, with concentrate pellets ad libitum in the afternoon; or C, ad libitum the same grain mixture together with concentrate pellets and oystershell grit in the ratio 70 : 23 : 7 so that the nutritive value of the complete diet was similar to that of the conventional mash. The concentrate pellets used in the two regimes differed. Those used in regime B contained ground limestone while those used in regime C did not.

Egg production was similar on the three regimes (74.8, 74.7 and 74.5% respectively) . Food intake was lowest on regime C and highest on regime B, although the intakes of metabolisable energy were very similar on the three regimes. Compared with the results obtained with the conventional mash diet (regime A), the conversions of food and dietary protein to eggs were lower on regime B but higher on regime C.     

Short- and Long-Term Effects of Feed Form on Fast- and Slow-Growing Broilers

Three experiments were conduced to quantify the potential negative effect of fine particles (<0.5 mm diameter) in the feed on fast- and slow-growing broiler growth performance. In the first experiment, chickens were fed mash or pellets of 2.5 and 4 mm diameter between 15 and 35 d of age. During this period, fast-growing broiler fed pelleted feed had a 19% higher final BW, a 12% higher feed intake, and a 12% lower (improved) feed conversion ratio than those fed mash. Feed form had no significant effect on feed intake, BW gain, or final BW of slow-growing chickens. Feed conversion ratio, however, was 6% lower with pellet than mash. In the second and the third experiments, fast and slow-growing chickens weighed 1.2 kg at the beginning of the experiment. In the second experiment, the effects of a transition from pelleted feed to mash or a mixture between the 2 feed forms on the short-term feed intake and growth was investigated. After the transition from pellet to mash or the mixture, both fast- and slow-growing chickens adapted their feed intake in less than 10 min. The mixture between mash and pellets led to a 25% higher feed intake and an 18% lower feed conversion ratio for fast-growing chickens. There was no significant difference between mash and the mixture on slow-growing feed intake, but feed conversion ratio was 9% lower. In the third experiment, the effect of fine particles concentration in the feed on short-term growth response was measured. Increase in the concentration of fine particles in the feed linearly reduced feed intake and BW gain of both fast- and slow-growing chickens. However, the slope was 5 times greater for fast-growing chickens than for slow-growing chickens. These 3 experiments showed that fast-growing chickens are more sensitive to feed form than slow-growing chickens. Therefore, physical form of the feed can be a major limiting factor of performance.     

The Effect of Steam-Conditioning Practices on Pellet Quality and Growing Broiler Nutritional Value

Feed currently constitutes 60 to 65% of the total cost of broiler production. Pellets are the primary feed form for commercially reared broilers. Understanding how to optimize pellet quality through precision thermo-mechanical processing may impact broiler performance and nutrient availability, and thus cost of production. Steam conditioning represents a manipulable thermo-mechanical processing variable. Corn-soybean meal-based diets were conditioned with 1 of 4 steam pressure × temperature combinations: 138 kPa at 82.2°C, 138 kPa at 93.3°C, 552 kPa at 82.2°C, or 552 kPa at 93.3°C. High steam pressure and temperature conditioning were shown to increase pellet quality. Three additional diets were prepared: unprocessed mash, the 552 kPa/93.3°C diet reground to mash, and a 50:50 combination of pellets and mash produced from the 552 kPa/93.3°C treatment to simulate a high fine percentage diet. All diets were fed to Cobb 500 broilers from 21 to 38 d, and nutrient availability was determined with Single Comb White Leghorn roosters. Broilers fed pellets conditioned with high steam temperature demonstrated decreased feed intake and feed conversion ratio. Amino acid and energy availability were not affected by variations in steam conditioning.     

Controlled early feed restriction as a potential means of reducing the incidence of ascites in broilers.

Male broiler chicks were grown at cold temperatures to enhance susceptibility to the ascites syndrome. Various feeding regimens were used to determine whether they could influence mortality due to ascites. It was found that a precisely controlled early feed-restriction regimen at the age of 6 to 11 days significantly reduced mortality from all causes and mortality due to ascites, while maintaining optimum body weight and feed conversion at marketing age.     

Early-age cold conditioning of broilers: effects of timing and temperature

1. The aim of the present study was to determine the effects of early-age cold conditioning (CC) on performance, ascites mortality, thyroid hormones status and immune response (leucocytes count) of broiler chickens.

2. A total of 336 chicks at 2 and 3?d of age were exposed to 20 or 25°C (for 3 or 6?h) in a 2?×?2?×?2 factorial experiment, while a control group was kept under normal temperature conditions (30°C). Thereafter, both control and cold conditioned birds were reared under standard conditions until 42?d of age.

3. The results showed that performance (weight gain and feed efficiency) was improved by CC at the end of the rearing period. Carcase traits (breast, thigh and abdominal fat percentage) were not affected by different treatments. Heart weight was lower in cold conditioned birds accompanied with lower ascites mortality. Total leucocyte count was higher in CC birds. Higher concentrations of thyroxin (T₄) were found in plasma of treated groups, while triiodothyronine (T₃) to T₄ ratio was decreased.

4. In conclusion, it seems that early age CC improves performance and reduces ascites mortality of broilers through altered thyroid hormones metabolism and leucocyte function. According to the results, the best timing for CC of broilers was 20°C for 6?h at the age of 2?d, and no significant benefit was observed by repeated CC.     

Effect of a new pelleting process on the level of contamination of poultry mash by Escherichia coli and Salmonella

The efficacy of a new pelleting process in eliminating naturally occurring Escherichia coli and salmonella from poultry mash was assessed by comparing the microbial load in raw and processed mash. Instead of using steam produced in a boiler, the new process conditioned mash in an Original Vertical Conditioner with steam and other hot gases generated by direct combustion in a Vaporator. E. coli was isolated from 72-100% of samples of raw mash in all trials, and the mean number of colony-forming units of E. coli/g of samples was 6.8 +/- 4.0 X 10(4). Salmonellae (S. senftenberg, S. bredeney, and S. mbandaka) were isolated from 5-10% of samples of raw mash utilized in three of the seven trials. Within limitations of the sampling and analytical tests utilized, the new pelleting process eliminated salmonella from all mash in which the organism was known to be present but eliminated E. coli in only three trials. The process appeared to be 100% effective against both organisms when mash entering the pellet mill from the conditioner had a temperature of 85.7 C and a moisture content of 14.5% and had been retained and treated with steam and hot gases for 4.1 minutes.     

Possibilities for preservation of coarse particles in pelleting process to improve feed quality characteristics

Poultry diets are mainly used in pelleted form because pellets have many advantages compared to mash feed. On the other hand, pelleting causes reduction of feed particle size. The aim of this research was to investigate the possibility of increasing the content of coarse particles in pellets, and, at the same time, to produce pellets with satisfactory quality. In this research, the three grinding treatments of corn were applied using hammer mill with three sieve openings diameter: 3 mm (HM‐3), 6 mm (HM‐6) and 9 mm (HM‐9). These grinding treatments were combined in pelleting process with three gaps between rollers and the die of pellet press (roller‐die gap, RDG) (0.30, 1.15 and 2.00 mm) and three moisture contents of the pelleted material (14.5, 16.0 and 17.5%). The increased coarseness of grinding by the hammer mill resulted in the increased amount of coarse particles in pellets, especially when the smallest RDG was applied (0.30 mm), but pellet quality was greatly reduced. Increasing of RDG improved the quality of pellets produced from coarsely ground corn, but reduced the content of coarse particles in pellets and increased specific energy consumption of the pellet press. Increasing the moisture content of material to be pelleted (MC) significantly reduced energy consumption of the pellet press, but there was no significant influence of MC on particle size after pelleting and on the pellet quality. The optimal values of the pelleting process parameters were determined using desirability function method. The results of optimization process showed that to achieve the highest possible quantity of coarse particles in the pellets, and to produce pellets of satisfactory quality, with the lowest possible energy consumption of the pellet press, the coarsest grinding on hammer mill (HM‐9), the largest RDG (2 mm) and the highest MC (17.5%) should be applied.     

Effects of early feed restriction and cold temperature on lipid peroxidation, pulmonary vascular remodelling and ascites morbidity in broilers under normal and cold temperature

Two experiments were conducted to evaluate the effects of early feed restriction on lipid peroxidation, pulmonary vascular remodelling and ascites incidence in broilers under normal and low ambient temperature. In experiment 1, the restricted birds were fed 8h per day either from 7 to 14 d or from 7 to 21 d, while the controlled birds were fed ad libitum. In experiment 2, the restricted birds were fed 80 or 60% of the previous 24-h feed consumption of full-fed controls for 7 d from 7 to 14 d. On d 14, half of the birds in each treatment both in experiment 1 and experiment 2 were exposed to low ambient temperature to induce ascites. Body weight and feed conversion ratio were measured weekly. The incidences of ascites and other disease were recorded to determine ascites morbidity and total mortality. Blood samples were taken on d 14, 21, 28, 35 and 42 to measure the plasma malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). On d 42, samples were taken to determine the right/total ventricular weight ratio (RV/TV), vessel wall area/vessel total area ratio (WA/TA) and mean media thickness in pulmonary arterioles (mMTPA). Low-temperature treatment increased plasma MDA concentration. When broilers were exposed to a cool environment for 3 weeks, plasma SOD and GSH-Px activity were decreased compared with normal-temperature chicks. RV/TV, WA/TA and mMTPA on d 42 were increased in birds exposed to cold, consistent with the increased pulmonary hypertension and ascites morbidity. Early feed restriction markedly decreased plasma MDA concentration. The plasma SOD and GSH-Px activity of feed-restricted birds were markedly higher than those fed ad libitum on d 35 and d 42. All early feed restriction treatments reduced ascites morbidity and total mortality. On d 42, the RV/TV, WA/TA and mMTPA of feed-restricted broilers were lower than that of the ad libitum-fed broilers. The results suggested that early feed restriction alleviated the lipid peroxidation, promoted the activity of enzymatic antioxidant and inhibited pulmonary vascular remodelling. These changes might be associated with reduced ascites incidence.     

Incidence of pecking damage in growing bantams in relation to food form, group size, stocking density, dietary tryptophan concentration and dietary protein source

1. This paper reports 4 experiments with groups of 10 to 20 growing bantams in multi-unit brooders, which investigated effects of certain environmental and dietary factors on development of feather pecking damage to 6 weeks of age. Damage was assessed according to a subjective scoring system. 2. A test of food form (pellets, mash, mash diluted with 100 g/kg powdered cellulose) confirmed that pecking damage tends to be greater with pellets than with mash but there was no significant difference between the low damage scores associated with undiluted and diluted mash treatments. 3. A test of group size (10, 20 birds) and stocking density (744, 372, 186 cm2/bird) showed that variation in pecking damage was associated with group size x density interactions. 4. A test of dietary supplementation with L-tryptophan (0, 10, 20 g/kg) showed suppression of pecking damage with the higher (20 g/kg) dose, compared with the control (0 g/kg) treatment. 5. A test of dietary protein source (plant, mainly animal, mainly semipurified) showed no difference in pecking damage scores between treatments.     

Stress and feather pecking in laying hens in relation to housing conditions

1. Possible association between high rates of feather pecking and increased stress were investigated in laying hens. 2. From week 19 to week 30 after hatching, 16 groups of 11 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without long-cut straw as foraging material and provided with food in the form of pellets or mash. 3. Stress was assessed by egg production, weight gain, tonic immobility (TI), heterophil/lymphocyte (H/L) ratio and antibody titres to sheep red blood cells (SRBC), tetanus toxoid (TT) and human serum albumin (HSA). 4. Provision of foraging material and food form influenced feather pecking. Rates of feather pecking were highest in groups housed without straw and fed on pellets. 5. Egg production was reduced in pens without straw but not affected by food form. Both the duration of TI and H/L ratios were influenced by provision of foraging material and food form. TI was longer and H/L ratios were increased in hens housed without straw and in those fed on pellets. Antibody titers to SRBC and TT were lower in pens without straw than with straw but not influenced by food form. 6. In conclusion, foraging material and food form affected both feather pecking and indicators of stress, suggesting that feather pecking in laying hens is associated with stress.     

The effects of pelleting and glucanase supplementation in hulled barley based diets on feed manufacture,broiler performance,and digesta viscosity

Feeding broilers barley-based diets requires special consideration primarily due to effects on increased digesta viscosity and decreased nutrient digestion. Pelleting and glucanase supplementation are commonly performed prior to feeding broilers barley-based diets; however, the interaction of these practices is complex. The objective of this study was to establish a comprehensive evaluation of glucanase efficacy including: degree of processing, activity postpelleting, broiler performance, and digesta viscosity. Treatments were arranged in a 5 (diet formulation) × 2 (processing) factorial in a randomized complete block design with 8 replications/treatment. The 5 diet formulations consisted of positive control (PC), negative control (NC), glucanase A (GA) 125 or 1,000 β-Glu-U/kg feed, and glucanase B (GB) 1,000 β-Glu-U/kg feed. The PC and NC diets differed in metabolizable energy by 150 kcal/kg and enzymes were added to NC formulations. Diets were either fed as unprocessed mash or ground pellets. Diet formulation × processing did not interact for feed intake (FI), FCR, or total tract viscosity (P > 0.05); however, a trend was observed for ending bird weight, demonstrating that for ground pellets, GA 1,000 β-Glu-U/kg feed was improved relative to NC and similar to PC (P = 0.0903). Benefits associated with GB were not of similar magnitude, perhaps in part due to a 50% decrease in activity postpelleting. In addition, GA benefits were not suggested for unprocessed mash. The main effect processing was significant (P < 0.0001) demonstrating that broilers fed ground pellets resulted in greater pen ending bird weight, FI, and bird live weight gain (LWG) compared to birds fed unprocessed mash diets. Evaluations of glucanase should go beyond in vitro activity and include live bird performance using feed that has undergone pelleting.     

Effect of Corn Particle Size and Pellet Texture on Broiler Performance in the Growing Phase

A review of past literature revealed inconsistencies in recommended grain particle size for optimal broiler performance. Changing diet formulation and subsequent processing variables may alter pellet texture and potentially affect broiler performance. In the current study, ground corn, varying in size (781, 950, 1,042, 1,109, and 2,242 μm), was added to a soybean-based premix to create 5 different mash diets. Water and a commercial pellet binder were added separately to corn-soybean-based diets before steam pelleting to create 2 pelleted diets differing in texture (soft and hard, respectively). The objective was to evaluate corn particle size, pellet texture, and feed form variation of compound diets on 3- to 6-wk broiler performance, nutrient retention, carcass characteristics, TME_n, feed passage time, and particle size preference. Soft and hard pellets had similar pellet durability (90.4 and 86.2%, respectively) and fines (44.5 and 40.3%, respectively). Increasing particle size of mash diets improved nutrient retention. However, broiler performance and energy metabolism were decreased when corn particle size exceeded 1,042 μm. This observation was due, in part, to increased size and maintenance requirement of the gastrointestinal tract. Broilers fed hard pellets (1,856 g of pellet breaking force) had improved nutrient retention, TME_n, and subsequent performance compared with broilers fed soft pellets (1,662 g of pellet breaking force). Pellet texture may affect broilers in a manner similar to particle size.     

Disease-induced variability of genetic correlations: ascites in broilers as a case study

Breeding against a production disease is complicated by multiple relationships between productivity, disease, and environment. Ascites in broilers is such a disease. The combination of the reasonably well understood etiology (a physiological/pathological cascade due to inadequate oxygen supply) and the practical relevance makes ascites a relevant case for demonstrating and partly revealing these complex relationships. Chickens (n = 2,788) were tested in an ascites-challenging (cold) environment. Genetic analysis of mortality and pathology in combination with performance and physiological traits (especially blood gas traits) revealed ample opportunities for selection against ascites expression. The genetic correlation structure indicated that different mortality traits and pathology traits roughly represent one common characteristic. Direct selection against pathology is more effective than selection on the basis of growth or blood gas traits. The observed negative correlation (-0.26) between productivity and ascites was unexpected. From the etiology of ascites (inadequate supply of oxygen relative to the demand), a positive (unfavorable) correlation was expected. To demonstrate that the actual disease occurrence caused this apparent contradiction, the data from the undiseased subpopulation were reanalyzed. In the undiseased subpopulation, the genetic correlation between productivity and ascites was positive (0.29). This discrepancy was confirmed by comparing regression of ascites expression on actual performance with regression of ascites on independently assessed performance breeding values. The lability of the genetic correlation was explained from complex interactions between productivity, disease susceptibility, and actual occurrence of the disease. The revealed mechanism can be generalized to other production-related diseases and results in systematically lower genetic correlations between disease and productivity. It was inferred that genetic correlations between productivity and such diseases will always be prone to the demonstrated environmental sensitivity, which complicates index selection against production-related diseases.