The effect of environmental temperature and body weight on growth rate and feed:gain of male broilers

High environmental temperatures are detrimental to the growth and feed:gain of broilers. The objective of this research was to determine the effects of incremental differences in environmental temperature on growth and feed:gain. The data are needed for decisions about the profitability of energy inputs when managing the housing environment. In Trial 1, broiler chicks were reared as a group to 21 d on litter with constant lighting and with water and feed available for ad libitum consumption. They were then moved to 10 environmental chambers. Each chamber was set at a different temperature ranging from 21.1 C to 31.1 C in 1.11 C increments. Weight gain and feed:gain were determined when the broilers were 28, 35, and 42 d old. In Trials 2 and 3, broilers were placed in the environmental chambers, and weight gain and feed:gain were determined for the 42 to 49 d period. The data were analyzed statistically, and regression equations were obtained for growth and feed:gain. Equations were based on body weight and temperature, and the body weight equation was plotted as grams gain per bird per day. Feed:gain was plotted for that body weight and temperature. Body weight gain per day increased to a maximum with increasing weight and then declined. The body weight at the maximum rate of gain was inversely related to temperature. Feed:gain increased as body weight increased. Feed:gain was directly related to temperature at weights above 800 g and the effect of temperature increased as body weight increased. The data will be useful for the evaluation of various management scenarios to determine the inputs that are profitable.     

Further studies on the influence of genotype and dietary protein on the performance of broilers

An experiment was conducted to quantify genetic differences in response to dietary protein level of male vs female broilers. Broilers (1 d old) from a "high-yield" strain cross (Ross x Ross 208) and a "fast-growing" strain cross (Peterson x Arbor Acres) were placed on fresh pine shavings in floor pens. From Day 0 to 18, all birds were fed a 23% CP starter diet. During Days 18 to 53 male birds were fed either a 16, 18, 20, 22, 24, or 26% CP diet (3,200 kcal ME/kg) and female birds were fed the 16, 20, or 24% CP diet. Significant differences (P < 0.05) were noted in the performance of the different strains. Ross x Ross 208 male birds had a higher body weight (3.37 vs 3.16 kg), higher feed intake (7.08 vs 6.78 kg), higher breast yield (31.76 vs 29.25%), higher carcass yield (73.90 vs 71.85%), and a lower adjusted feed conversion ratio (FCR; 2.10 vs 2.16 g:g) than Peterson x Arbor Acres males at 53 d of age. As compared to Peterson x Arbor Acres females, Ross x Ross 208 female broilers also had a higher body weight (2.68 vs 2.55 kg), higher breast meat yield (33.61 vs 30.80%), higher carcass yield (75.31 vs 73.91%), and lower adjusted FCR (1.97 vs 2.04 g:g). Qualitative differences in the response of these strains were confirmed and better qualitative data is presented that can be used to predict the important output parameters from the import inputs in broiler production.     

Metabolic disturbances in male broilers of different strains. 1. Performance, mortality, and right ventricular hypertrophy

Two trials were carried out to test the susceptibility for metabolic disturbances of different strains of male broilers. In Trial 1, 1,890 male chickens were allotted in a randomized block design with seven treatments (Arbor Acres, Avian Farms, Cobb-500, Hubbard-Peterson, ISA, Naked Neck, and Ross) and six blocks of 45 chickens. Trial 2 involved 2,184 male chickens of six strains (Arbor Acres, Avian Farms, Cobb 500, Hubbard-Peterson, ISA Naked Neck, and Ross) allotted in seven complete blocks of 52 birds. The same management system was adopted for all birds, reared up to 42 d in an open house during late winter (Trial 1) or late autumn (Trial 2). The most marked differences observed among the strains tested was the lower BW and higher feed conversion of Naked Neck broilers. Total percentage mortalities were high among the most productive broilers, being more than 50% due to sudden death (SDS) and ascites syndrome (AS). No Naked Neck birds died as a consequence of these disturbances and the total mortalities were significantly lower (P < or = 0.05) than the other strains. The ratio of right ventricle weight to total ventricle weight of the dead birds was over 0.25, except for Naked Neck birds, which presented a nonhypertrophic ratio. The two trials confirmed the relationship between high productivity and high incidence of SDS and AS and indicated that Naked Neck male broilers are resistant to these metabolic disturbances.     

Growth performance, intestinal microbial populations, and serum cholesterol of broilers fed diets containing Lactobacillus cultures

A study was conducted to determine the effects of adherent Lactobacillus culture on growth performance, intestinal microbial population, and serum cholesterol level of broilers. Four dietary treatments, consisting of the basal diet (control), basal diet + 0.05, 0.10, or 0.15% Lactobacillus culture (LC), were fed to 2,000 Arbor Acres broiler chicks from 1 to 42 d of age (DOA). The chicks were randomly assigned to 40 cages (50 chicks per cage, 10 cages per diet). The experimental period was 42 d. Body weights and feed to gain ratio were measured at 21 and 42 DOA. The intestinal microbial populations and serum cholesterol levels were determined at 10, 20, 30, and 40 DOA. The results showed that body weights and feed to gain ratios were improved significantly (P < 0.05) when compared to control broilers for broilers fed diets containing 0.05 or 0.10% LC, but not 0.15% LC, at 21 and 42 DOA. Coliform counts in the cecum of birds receiving 0.05% LC at 10, 20, and 30 DOA, and 0.10% at 10 and 20 DOA were significantly lower (P < 0.05) than those of the control birds. The total aerobes, total anaerobes, lactobacilli, and streptococci in the small intestines and ceca of the control birds were not significantly different from those of the treated groups. Serum cholesterol levels were significantly lower (P < 0.05) in broilers fed the three diets containing LC at 30 DOA, and in the birds fed 0.05 or 0.10% LC at 20 DOA.     

Effect of feeding raw and treated common vetch seed (Vicia sativa) on the performance and egg quality parameters of laying hens

Two experiments were conducted to study the effect of feeding raw or treated common vetch seeds (V) on BW, feed intake (FI), egg production (EP), feed conversion (FC), egg weight (EW), shell thickness (ST), yolk color score (YC), and Haugh unit score (HU) of Single Comb White Leghorn hens for 56 d. In Experiment 1, diets contained 0, 7.5, 15, and 22.5% raw V. Compared with the control, the 22.5% V diet decreased (P < .05) BW, FI, and EP. In Experiment 2, intact or ground (G) V were either soaked (S) in water (1:5) for 24 h or autoclaved (A) at 103.5 x 10(3) Pa for 8 h, and then dried (D) at 55 C for 24 h. Eight diets were used, a corn soybean (control) and seven others, each containing 25% V, previously subjected to the forementioned treatments as follows: untreated V (UV), SDV, GSDV, ADV, GADV, SADV, and GSADV. Compared with the control, the UV diet decreased (P < .05) FI (75 vs 98 g) and EP (47.3 vs 88.7%), increased FC (1.99 vs 1.4 kg feed per dozen eggs), and induced BW loss (-63 vs 49 g). Soaking intact V improved (P < .05) FI (85 g) and EP (69%). Remaining treatments resulted in further improvement. Hens fed all V diets produced eggs with HU score 13 points better than that of the control (P < .05). In both experiments, EW, YC, and ST were not different among treatments. Results indicated that autoclaved V at 25% level was not detrimental to layers' performance.     

Research notes: Effect of environmental temperature on broiler chickens subjected to growth restriction at an early age

An experiment was carried out to evaluate the effect of early growth restriction (EGR) induced by feed restriction on the ability of male broiler chickens to withstand exposure to high environmental temperatures. A 2 x 4 factorial arrangement of treatments was employed to determine whether such an exposure affects the beneficial effect of EGR on performance and carcass quality. Chicks consumed feed ad libitum or were feed-restricted from 6 to 12 d of age (to achieve 60% growth of the ad libitum birds). From 4 to 8 wk of age, the chickens were kept in temperature-controlled chambers at 25, 30, 35 C and a diurnal cyclic temperature of 25:35 C. Weight gain, feed intake, and feed efficiency from 6 to 8 wk of age (after acclimatization to the various temperatures) and BW at 8 wk of age were significantly (P < or = 0.05) depressed by the high temperatures (35 and 25:35 C) compared with values observed at 25 and 30 C. Early growth restriction did not affect these variables. Relative heart, liver, and breast meat weights at 8 wk of age were decreased significantly with increasing temperature. Relative liver weight was also decreased significantly in the EGR chicks, whereas breast yield was increased significantly in these birds. Relative abdominal fat pad size was not affected by increasing the temperature from 25 to 35 C, but it was significantly lower in chickens kept at 25:35 C than in those kept at 25 and 35 C. Early growth restriction significantly reduced the size of abdominal fat. Because no significant interactions between EGR and ambient temperature on the above mentioned variables were observed during 4 to 8 wk of age, it is concluded that EGR can not alleviate the adverse effect of high ambient temperature on performance, nor can high ambient temperature obliterate the beneficial effect of EGR in improving feed efficiency and reducing fattening.     

Epidemiological study of Campylobacter spp. in broilers: source, time of colonization, and prevalence

From October 1993 to August 1994, broiler chickens in four grow-out houses, two previously used (houses 1 and 2) and two newly constructed (houses 3 and 4), were used in a study to determine the source, time of infection, and prevalence of Campylobacter spp. Cecal droppings and cecal samples were obtained from the broilers. Samples were also obtained from water, feed, litter, soil, fans, and workers' boots. Samples were obtained from domestic animals and wildlife species (rectal swabs), including insects, on or near the premises. Broilers in houses 2, 3, and 4 became infected in the second or third week and were fully colonized by day 42. Campylobacter appeared in house 1 during week 2 in a low percentage of the birds, disappearing by the fourth week. Isolates were also recovered from domestic pigs and water on this farm. In house 3, the organism was isolated from workers' boots and a wild bird prior to isolation from the broilers. Following isolation from cecal droppings, the organism was isolated from water, feed, litter, feathers, flies, cattle, feces, and wild animals. In house 2, Campylobacter was isolated from cattle feces and wild birds prior to week 5, when the broilers first became infected, and thereafter from water, feed, insect, and wildlife, and cecal droppings. It was subsequently isolated from workers' boots, cattle feces, feathers, insects, and other wildlife. All ceca taken from 20 birds each from houses 2 and 3 were positive at time of slaughter (day 49). All ceca from house 1 were negative. No ceca were collected from birds originating in house 4. No specific source could be identified from the samples obtained, although apparently the organism permeates the environment and several potential sources are discussed in this paper.     

Ureteroscopic management of lower ureteral stones: two years'' experience

1. This study was to determine the effects of heat load early in life on thermoregulatory responses and whole blood viscosity of broilers during a subsequent exposure to high environmental temperature later in life. 2. The birds, which had been subjected to exposure to 38 degrees C for 24 h at 5-d-old, served as prior exposure group (group A). Both group A and control group B were exposed to 33 degrees C for 3 h when near marketable weight. 3. On exposure to 33 degrees C, although there were no significant differences in the increases in heat production (HP) between the two groups, abdominal temperature (Ta), temperature of external ear tract (Tee), shank skin temperature (Tss), standing-lying frequency and lying time were lower in group A than in group B. Heart rate (HR) and comb surface temperature (Tcs) did not differ but increased in both groups during exposure to 33 degrees C. Respiration rate (RR) was greater in group A. 4. Blood viscosity decreased markedly in both groups after exposure to 33 degrees C; the decrease was greater in group A. 5. These results suggest that early exposure may promote broilers' ability to cope with the subsequent heat load by altering thermoregulatory physiological responses and behavioural patterns, resulting in an alleviation of heat stress.     

The relationship between parental yolk cholesterol and yolk fat concentration to abdominal fat content and feed conversion ratio of their respective offspring

The correlation of yolk cholesterol and yolk fat concentrations of egg from the pedigreed Athens-Canadian Randombred control population with the percentage of abdominal fat (AF) and feed conversion ratio (FCR) of their progeny were studied. The average yolk cholesterol, yolk fat, and AF were 20.3 mg/g yolk, 244 mg/g yolk, and 1.64%, respectively. The phenotypic correlation of both yolk cholesterol and yolk fat content of eggs from the parental population with AF or FCR of their progeny were low and nonsignificant.     

Duration of fertility in ad libitum and feed-restricted caged broiler breeders

It has been shown in previous studies that fertility can be reduced in overweight broiler breeder (BB) flocks. In an effort to determine the effect of ad libitum feeding on the duration of fertility in BB hens, 60 52-wk-old Shaver Starbro hens were randomly assigned to one of two treatments, ad libitum feeding (F) or restricted feeding (R) to maintain breeder target weights. All hens were reared to 52 wk under conditions of feed restriction. All birds were weighed individually on a weekly basis. At the beginning of each of two 4-wk study periods (56 to 60 wk and 60 wk to 64 wk), all birds were inseminated on 2 consecutive d with 0.05 mL pooled BB semen. All eggs were weighed and placed in a forced air incubator the same day that they were laid. After 7 to 10 d of incubation, the eggs were broken out and scored macroscopically as fertile with live embryo, fertile with dead embryo (early embryonic death), or clear (assumed infertile). The duration of fertility was defined as the number of days from the day after the second insemination to the last fertile egg before two consecutive interfile eggs. Hen BW were significantly different between treatments within each of the two 4-wk studies. The mean BW of the F hens was 4,261 g in Study 1 and 4,448 g in Study 2. The BW of the R hens were 3,459 g in Study 1 and 3,565 g in Study 2. Egg production levels and average egg weight was not different between treatments in either study. In Study 1, the duration of fertility for the F hens (12.7 d) and the R hens (12.7 d) were not different. In Study 2, the durations of fertility were significantly higher (P < 0.05) in the R hens (12.7 d) than in the F hens (10.0 d). These results support the theory that overweight BB have a reduced duration of fertility that may contribute to a reduced fertility in artificially inseminated and naturally mated flocks.     

Efficacy of different feeding levels of monensin in the control of coccidiosis in broilers

The feed level of monensin which gave maximal protection from coccidial infection in broilers reared in floor pens depended on the severity of the coccidial exposure and the criteria of infection studied. With indirect seeding of pens with coccidia (light coccidial exposure), 40 ppm was as efficacious as 100 ppm in improving weight gain, lesion score, and feed conversion. Statistical analysis with direct seeding (seeder birds; severe coccidial exposure) showed that feed levels of 84 and 102 ppm gave maximal improvement of weight gain and 4-week feed conversion, respectively. Further increasing the monensin level from 100 to 121 ppm did not improve weight gain and feed conversion at 8 weeks. Conversely, the relationship of plasma pigmentation and total lesion scores to monensin feed levels indicated that increasing the dosage of monensin from 100 to 121 ppm improved the performance of the broilers on the basis of these 2 infection indicators.     

Comparison of two ammoniation procedures to reduce the toxicity of endophyte-infected tall fescue seed fed to rats

To determine the effect of extending the duration of ammonia (2% dry matter basis) treatment ti'om 1 to 5 wk on the toxicity of endophyte-infected tall fescue seed, 60 male Harlan Sprague-Dawley rats were randomly assigned to the following six treatments during a 28-d trial: endophyte-free (E-), endophyte-infected (E+), 1 wk ammoniated endophyte-fee (1AE-), 1 wk ammoniated endophyte-infected (1AE+), 5 wk ammoniated endophyte-free (5AE-), and 5 wk ammoniated endophyte-infected (5AE+) tall fescue seed. The concentration of total pyrrolizidine alkaloids (N-acetyl and N-formyl loline) or E+ rescue was reduced from 4203 12 g/g to 3009 and 2533 I-tg/g by the 1AE+ and 5AE+ treatments, respectively. Ergovaline was lowered from 3.77 to 1.57 12 g/g by 1AE+ and eliminated by 5AE+. Endophyte-infected treatment groups had depressed (P < 0.0001) dally feed intakes (DFI), daily weight gains (DWG), feed efficiencies (G/F), primary antibody responses, and T cell and B cell mitogenic responses than endophyte-free treatment groups. Ammoniation of endophyte-infected rescue seed improved DFI and DWG (P < 0.0001) and G/F (P < 0.05); however, there was no difference in performance criteria between the 1-wk and 5-wk ammoniation treatments. Endophyte-induced depressions in immune function were not alleviated by ammoniation.     

Protection by a commercial Arkansas-type infectious bronchitis virus vaccine against a field isolate of the same serotype

A late-breaking infectious bronchitis virus (IBV)-associated respiratory disease was a chronic problem in Georgia broilers in 1995. The predominant virus isolated from diseased birds was the Arkansas (Ark) type of IBV. Because broilers in Georgia are currently vaccinated with the Arkansas serotype, there was concern that a phenotypic and/or genotypic change had occurred in the field virus so it could break through immunity conferred by commercial vaccines. The purpose of this study was to determine if a commercially available vaccine for IBV as currently used in the field still protected broilers against those viruses. We obtained 108 1-day-old broilers from a commercial source and assigned them randomly to 12 groups. One-half of the groups of birds were vaccinated at 1 day of age and again at 18 days of age with commercially available B1/Mass/Ark vaccine. One-half of both vaccinated and nonvaccinated groups of birds were challenged at 35 and 42 days of age with a recent IBV Ark field isolate. Serologic titers were evaluated by enzyme-linked immunosorbent assay at time of challenge and at the end of the trial. A necropsy was performed on birds at 56 days and pathogenicity was assessed. Seroconversion was statistically significant in all birds exposed to vaccine or challenge by 56 days of age. Gross airsacculitis was significantly more severe in broilers challenged without prior exposure to vaccine.     

The influence of extended posthatch holding time and placement density on broiler performance

Extended posthatch holding (in the hatcher) has been reported to dehydrate chicks, reduce broiler performance, and depress immune response. Nevertheless, some commercial hatcheries are increasing incubation time in an attempt to minimize possible bacterial contamination of incompletely healed navels. The objectives of this study were to determine the effects of posthatch holding on broiler performance and the effects of bird density and additive stress on performance and immune response. Twelve hundred broiler eggs (58 to 70 g) were incubated. Chicks were removed from the hatcher after 528 h of incubation, banded, and weighed. Half of the chicks were returned to the hatcher for an additional 24 h (HELD). Both hatcher treatments were placed at two densities (.07 and .12 m2 per bird). Individual BW were taken at 21 and 43 d of placement and 43 d of age. The HELD chicks weighed significantly less than controls at time of placement. At 21 d postplacement the HELD broilers were significantly heavier than controls, but were similar by 43 d. Total feed conversion was not affected in the HELD treatment, but birds in the .07 m2 per bird density were less efficient in terms of total feed conversion. Chick holding time and density seemed to affect antibody titers at 5 wk. Although holding chicks in the hatcher for 24 h did not clinically dehydrate chicks or affect performance, it decreased immune response. In addition to less efficient growth, birds in the more crowded pens had depressed immune response.     

Excess prevalence of non diabetic renal disease in native American children in Manitoba

An experiment was designed to compare BW and mortality of turkeys when three methods of beak trimming were utilized. Turkeys from six genetic lines were assigned to three beak trimming methods: arc beak trimming at hatching, hot-blade block trimming at 13 d, or hot-blade top-beak-only trimming at 13 d. Beak trimming method influenced 8-wk BW of three lines of females, but did not affect female BW at 16 wk. Beak trimming method influenced 8-wk BW of males from one line and 16-wk BW of a different line. There were no effects of method of beak trimming on 20-wk BW of either males or females from any line. Neither lines nor beak treatments differed in mortality.     

Pancreatic secretion of zinc and carboxypeptidase A and B in growing pigs

Responses to supplemental dietary L-carnitine of broilers fed on diets with different levels of metabolizable energy (ME) were investigated using growth performance and some carcass measurements. Three isonitrogenous diets containing 13.5, 12.8 or 12.2 MJ ME/kg were formulated, with or without supplemental L-carnitine (50 mg/kg) and fed ad libitum from 18 to 53 d of age. Supplemental L-carnitine increased body-weight gain (BWG) and improved feed conversion (FC) during the first 2 weeks of study. FC was also improved during the fourth week of the experiment. Weights of breast yield and thigh meat yield were significantly increased, whereas quantity and percentage of abdominal fat were reduced by supplemental L-carnitine. A significant interaction between supplemental dietary L-carnitine and dietary energy level was noted for BWG and FC during the second week of study.     

Nutritional aspects of hydrogenated and regular soybean oil added to diets of broiler chickens

The objective of the present study was to evaluate the effect of degree of saturation of fat incorporated into broiler diets on performance and body fatty acid (FA) profile. The various degrees of saturation were achieved by using regular soybean oil (SO) and hydrogenated soybean oil (HSO), mixed at different proportions. The work was carried out on commercial broilers (Experiment 1) and on lines of chickens divergently selected for high (HF) or low (LF) abdominal fat (Experiment 2). Daily BW gain and gain:feed ratio increased and the amount of feed intake decreased as the dietary fat saturation decreased. Digestibility of total fat and of each of the FA was lowest in the HSO group and reached maximal values when 23% or more of the added oil was SO. The AMEn values of the diets were almost parallel to fat digestibility. The performance of the HF and LF chickens was affected by the degree of saturation similarly to that observed for the commercial stock. The degree of dietary fat saturation had very little effect on saturated FA (C16:0 and C18:0) in body lipids, reduced the level of monoenoic FA (C16:1 and C18:1), and raised that of polyunsaturated FA (PUFA) (C18:2, C18:3, and C20:4). Monoenoic FA were higher, whereas PUFA were lower in the HF than in the LF line. The improved AMEn in diets containing unsaturated fat is probably due to higher fat digestibility, direct deposition of PUFA in body lipids, and lower lipogenesis, associated with lower heat production.     

Management of withdrawal syndromes and relapse prevention in drug and alcohol dependence

1. The first objective was to evaluate baseline heart rate (HR) responses in fast growing broilers fed ad libitum from 1 to 45d or subjected to a food restriction (85%, 70% and 55% of ad libitum from 7 to 21d) and a refeeding (22 to 45d) regimen in a normal thermal environment. The second was to evaluate HR and haematocrit responses in fast growing broilers reared at a low environmental temperature and fed ad libitum (A-L) from 1 to 42d, subjected to food restriction (70% ad libitum) between 7 to 21d and refed thereafter (R-R), or subjected to food restriction between 7 to 42d (R), and to follow the changes in normal birds and those prone to ascites. 2. The baseline HR in the normal thermal environment at 21 and 45d in birds fed ad libitum was lower (P < 0.001) than at 7d. The food-restricted groups had higher HRs at 21d than at 7d, with the differences significant (P < 0.01) for the 70% and 55% treatments. At 21d the HRs in restricted groups were significantly higher (P < 0.01) than in ad libitum-fed birds. After returning to ad libitum feeding the HRs in these birds tended to decline, with the differences significant (P < 0.05) for the 70% and 55% treatments. 3. In the birds exposed to cold, each feeding regimen produced distinct patterns of change in HR and haematocrit. Both feeding regimen and age had significant (P < 0.001) effects on the changes of both variables. Relative to 7d, on 14d and 21d the HRs decreased and haematocrits increased in all groups, but the rates of change were highest in the A-L and R-R birds. The first fulminant cases of ascites were observed during the third week in the A-L group and during the fourth week in the R-R group. None of the chickens from the R group developed ascites. Altogether, the incidence of ascites was 48% in the A-L group and 28% in the R-R group. 4. Among the birds exposed to cold, the ascitic birds had significantly (P < 0.001) lower HRs and higher haematocrits than normal birds from the same feeding regimen group. The time trends in the rates of change in HR and haematocrit were distinctly different (P < 0.001) for ascitic and normal birds. The change in feeding regimen from restricted to ad libitum in the R-R group resulted in a significant (P < 0.001) decrease in HR and increase in haematocrit. 5. In view of the evidence presented, it appears that hypoxaemia and tissue hypoxia in broiler chickens may be a result of circulatory insufficiency associated with progressive bradycardia rather than, as commonly believed, pulmonary insufficiency. In this situation the pulmonary hypertension may be a secondary symptom.     

Effects of a hydrated sodium calcium aluminosilicate (T-Bind) on mycotoxicosis in young broiler chickens

Experiments were conducted to determine the ability of a hydrated sodium calcium aluminosilicate (T-Bind) sorbent to reduce the toxicity of aflatoxins (AF) or T-2 toxin in male broiler chickens from day of hatch to 21 d of age. In Experiment 1, the sorbent was added at 0.250 or 0.375% to diets containing AF at 5 or T-2 toxin at 8 mg/kg of diet. When compared with controls, AF reduced BW gain by 27% and T-2 toxin reduced BW gain by 17%. The addition of the sorbent at 0.250 or 0.375%, in the absence of added mycotoxins, did not alter the performance of the chicks. The sorbent reduced the toxic effects of 5 mg AF/kg of diet on BW gain by 43% but did not significantly diminish the toxic effects of 8 mg T-2 toxin/kg of diet. The decreased efficiency of feed utilization and the increased relative organ weights caused by AF were significantly diminished to differing degrees by the sorbent. Oral lesions caused by T-2 toxin were not affected by the sorbent. In Experiment 2, the sorbent was added at 0.80% to a diet containing 8 mg T-2 toxin/kg of diet. The sorbent did not diminish the toxic effects of T-2 toxin when added at 0.80% of the diet. These data demonstrate that this specific sorbent can provide protection against the toxicity of AF, but not T-2 toxin, in young broiler chicks.     

Blood viscosity in broilers: influence on pulmonary hypertension syndrome

Elevation in apparent blood viscosity may enhance the pulmonary hypertension that leads to pulmonary hypertension syndrome (PHS) and ascites in fast-growing broilers. We investigated the importance of packed cell volume (PCV) and shear rate in modifying apparent viscosity of the blood from broilers assigned to normal, preascites, and ascites groups. Apparent viscosity of broiler blood increased at all shear rates as PCV increased; the increase in apparent viscosity became greater as the shear rate decreased at PCV above 0.30. At the PCV of normal broilers (0.30 or below), apparent viscosity was nearly shear rate independent, at least down to 11.25 per second, the lowest shear rate studied. Apparent viscosity, at any given PCV and shear rate, was significantly lower in the blood of birds with ascites than in normal birds; however, the relative viscosity was not different between those groups, indicating that lower plasma viscosity in the birds with PHS was responsible for the finding. The results show that the principal factor responsible for increased apparent viscosity of blood in birds with PHS is the increase in PCV. The increased resistance to flow of blood as the result of higher blood viscosity may contribute to the pulmonary hypertension.