Water intake and water concentration in the body and gastrointestinal tract of intermittently fed broiler chickens

The relationship between water intake and water concentration in the body and in the gastrointestinal contents was studied in meat-type chickens fed either intermittently or ad libitum, as controls. In experiment 1, male broilers were reared from 12 to 33 d of age and were fed every second day or ad libitum. The water consumption of the intermittently-fed birds on days of food removal was 31% of the consumption of the control group. On days of food restoration their water consumption exceeded that of the controls, by 27%. No significant differences in water:food ratios were found between birds fed intermittently or the controls on days of food restoration. The restricted birds had a lower fat and a higher protein concentration in the body. No relationship was found between water:food ratio and body composition. In experiment 2, birds were kept on the same feeding regimes from 12 to 46 d of age. The water content of the pancreas increased after food restoration compared with ad libitum feeding or food deprivation. The amount of water in the gastrointestinal contents increased progressively from crop to ileum. The feeding regimens had no effect on the water content of the intestine.     

Exogenous leptin advances puberty in domestic hen

The present study was undertaken to examine the effect of recombinant chicken leptin administered to fed ad libitum and feed-restricted immature chickens of a layer strain on ovarian development and the timing of sexual maturity. In the first experiment 11-week-old pullets (77 days of age) fed ad libitum were injected daily with leptin at four dose levels (4, 16, 64 and 256 microg/kg body weight) until sexual maturity (lay of the first egg). Leptin treatment at the highest dose significantly (P<0.05) advanced the onset of puberty (day 116.3+/-1.0) in comparison to controls (day 121.3+/-1.2). The rises of luteinizing hormone, estradiol and progesterone in blood plasma were also advanced by leptin treatment. In the second experiment, both full-fed and feed-restricted pullets (79 days of age) were injected daily with leptin (256 microg/kg body weight). In birds fed ad libitum, exogenous leptin again significantly (P<0.05) advanced first ovipostion (day 118.4+/-1.4 versus day 124.4+/-1.7), while abolishing the significant (P<0.05) delay caused by feed restriction (day 131.5+/-1.6) and restoring the normal onset of sexual maturity (day 125.7+/-1.6). Analysis of the ovaries in 106-day-old pullets revealed that leptin injections advanced follicular development, particularly in birds fed ad libitum, and significantly (P<0.01) reduced follicular apoptosis both in full-fed and feed-restricted birds. In conclusion, we have shown that in female chickens exogenous leptin advances the onset of puberty by attenuation of ovarian apoptosis and enhancement of folliculogenesis.     

Welfare assessment of modified rearing programmes for broiler breeders

1. Female broiler breeders were fed ad libitum or a restricted quantity of food to achieve either a recommended body weight curve or a modified (linear) growth curve that allowed more generous feeding between 6 and 15 weeks of age. The birds were fed a ration containing either a normal or low concentration of crude protein. The welfare of the birds was assessed using a profile of indices of welfare at 6, 12, 18 and 24 weeks of age. 2. The low-protein ration decreased the body weight of birds fed ad libitum and restricted birds were fed substantially more of the low-protein ration to meet target body weights from 3 to 14 weeks of age. 3. The modified restricted rearing programme did not have an effect on indices of welfare. 4. Water intakes and plasma corticosterone concentrations were lower in restricted birds fed the low-protein ration and they spent more time resting, and less time spot-pecking, than birds fed the high-protein ration. 5. Birds fed ad libitum on both rations spent more time resting and less time foraging, drinking and spot-pecking than food restricted birds and were more fearful than restricted birds at 6, 12 and 18 weeks of age. 6. The heterophil:lymphocyte ratio in restricted birds was higher at 6 weeks and lower at 24 weeks compared with birds fed ad libitum. Humoral immunity was lower at 6 weeks of age in birds fed ad libitum and was similar at other ages. Cell-mediated immunity was similar among all treatments. 7. Plasma corticosterone concentrations were higher in restricted birds compared with birds fed ad libitum. Plasma creatine kinase activity was higher in birds fed ad libitum at 6, 12 and 18 weeks of age. Alkaline phosphatase and lactate dehydrogenase activity were higher whereas AST was lower in restricted birds compared with those fed ad libitum. 8. There was no evidence to support the use of low protein rations or linear growth curves to improve welfare in restricted broiler breeder females.     

半胱胺对鸡免疫器官组织结构及发育的影响

为研究半胱胺对鸡免疫器官发育的影响,试验应用100羽1日龄草杂鸡,随机分成2组,每组50羽,即:对照组和试验组:分别饲喂添加0和1.0g/kg半胱胺的基础日粮.试验期30d.试验结束时每组随机抽取20只鸡,颈静脉放血致死,取胸腺、法氏囊和脾脏,应用Bouin液固定,制作石蜡切片,H·E染色,Olympus显微镜观察、拍照.结果表明,试验组鸡较对照组鸡胸腺小叶皮质增厚,皮质内淋巴细胞密集,胸腺小体减少;试验组较对照组鸡法氏囊淋巴小结增多,淋巴细胞处于发育状态,皮质较厚,皮质、髓质内淋巴细胞增多,皮质、髓质分界明显.对照组法氏囊出现萎缩退化现象;试验组鸡较对照组鸡脾脏的结构清晰,白髓内的脾小结数量增多,研究结果显示,日粮中添加半胱胺能够促进鸡的淋巴器官的发育,从而提高机体的免疫功能.     

Effects of photostimulation at 18, 24 and 30 weeks of age on the productivity of female turkeys fed ad libitum or restricted until point of lay.

1. Turkey females were fed ad libitum or restricted from 6 weeks of age to achieve mean body weights of 0.6 of ad libitum fed birds on photostimulation at 18, 24 or 30 weeks of age. Body weight, food intake, egg production and hatchability were recorded to 54 weeks of age. 2. Restricted turkeys were fed ad libitum after first egg or 36 weeks of age. Food intake after 30 weeks of age averaged 170 g/bird/d and was similar for all treatments. At 54 weeks of age, restricted turkeys photostimulated at 24 and 30 weeks were not as heavy as turkeys photostimulated at 18 weeks and ad libitum fed turkeys. 3. A large proportion of restricted turkeys photostimulated at 18 weeks of age did not commence lay until 30 to 40 weeks and a significant number of restricted birds photostimulated at 24 weeks had short laying cycles. Restricted birds photostimulated at 30 weeks came into lay and showed similar persistency of lay to ad libitum fed turkeys. 4. Ad libitum fed turkeys laid 115.0, 122.0 and 101.0 and restricted turkeys 92.4, 99.5 and 103.4 eggs when photostimulated at 18, 24 and 30 weeks, respectively. The number of non-settable eggs was lower in restricted compared with ad libitum fed turkeys and declined with age at photostimulation. 5. Egg size at the end of the experiment was similar for ad libitum fed turkeys and restricted birds photostimulated at 18 weeks but was 2.3 g lower for restricted birds photostimulated at 24 and 30 weeks of age. 6. Hatchability was higher, and the proportion of second quality poults was lower with eggs from restricted turkeys. The mean numbers of poults hatched were 59.9, 75.1 and 66.0 for ad libitum fed and 71.7, 65.7 and 79.4 for restricted turkeys photostimulated at 18, 24 and 30 weeks of age.     

Energy and nitrogen metabolism of diseased chickens: aflatoxicosis.

1. New Hampshire chicks were fed on diets containing 0 (control), 0-7 (A), or 1-1 (B) ppm of aflatoxin B1. In two trials 1-d-old chicks were offered ad libitum the three diets for 14 d. The gaseous exchange of five chickens from each group was measured for 3 or 4 d, the same diets being fed, at 2, 3, 4 and 5 weeks of age in two series of experiments. The controls were fed at the lower intake of the two other groups. Following each series of experiments at the various ages, birds were starved for 24 h and their heat production was re-measured over the next 24 h. 2. Mortality was highest and growth and food conversion poorest where the diet with the highest aflatoxin concentration was fed. Mortality was confined to the first 2 weeks. 3. Performance of birds in the chambers was improved in the second series due to differences in food intake. It also improved with age suggesting some resistance to the toxin. 4. Mean respiratory quotient was 0-97 for fed chickens on diet B. This was significantly different from 0-92 for the two other groups. Similarly, during starvation the RQ was 0-76 compared with 0-73. 5. birds fed on diet B generally grew better, retained more nitrogen and had a better energy balance in the respiration chambers than the other two groups. Metabolisability of dietary energy was less (68.5%) for all groups at 2 to 3 weeks than when older (70%) but availability of ME was the same (71%) for all groups. 6. Heat production (kJ/kg0-75) of starved birds on diet B was significantly lower than the other two groups, while endogenous nitrogen excretion was higher. 7. Water consumption (ml/g food and g/100 g body weight) was greatest for birds on diet B. 8. Although aflatoxin in the diet substantially reduced intake there was no indication that at these reduced levels of intake, nitrogen or energy metabolism were measurably impaired.     

Progressive bradycardia,a possible factor in the pathogenesis of ascites in fast growing broiler chickens raised at low altitude

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.     

Metabolic and anatomical adaptations of heavy-bodied chicks to intermittent feeding. 2. Pancreatic digestive enzymes.

1. Activities of digestive enzymes in meat-type chickens under ad libitum or alternate-day feeding were determined from 14 to 83 d of age. 2. Final body weight of intermittently fed birds attained 75% of that of the ad libitum-fed controls. 3. When compared with the ad libitum-fed counterparts, a marked increase in the relative weight of the pancreas and intestinal contents were found on repletion days. On depletion days the relative weights of the pancreas and of the intestinal contents were about half those found in ad libitum-fed birds. 4. The activity of the digestive enzymes in the pancreas, expressed as U/g pancreas or U/kg body weight, was not affected consistently by the feeding regime. In the small intestine a marked increase in relative activity (U/kg body weight) was observed on repletion days and a marked decrease on depletion days as compared with ad libitum-fed controls. The activities per g intestinal contents following food restoration did not differ significantly from those of ad libitum-fed controls except for trypsin, which was higher in the former. On depletion days the activities per g intestinal contents were lowest, lipase excepted.     

Comparison of haematological values in restricted- and ad libitum-fed domestic fowls: white blood cells and thrombocytes

1. White blood cells and thrombocyte values were examined in normal domestic fowls of layer and broiler strains fed restricted or ad libitum diets. 2. Basophils were the only white blood cells to increase significantly in number after the period of food restriction. It is suggested that the increase may have been associated with stress. 3. There were more basophils in broilers than layers, in males than females and in younger than older birds. 4. In contrast, a decrease in the total number of white blood cells was seen in birds maintained on a restricted diet compared with those fed ad libitum. 5. Stress may also have been responsible for an increased thrombocyte count in the restricted birds as well as a slightly lowered eosinophil count. 6. Heterophil/lymphocyte ratios were not significantly altered by the restriction of food.     

Plasma oestrogen and triglyceride concentrations and reproductive characteristics of broiler chickens after ten generations of selection at seven weeks of age for high or low plasma very low density lipoprotein concentration.

1. Day old female chicks from two lines of broilers, selected for high or low plasma concentrations of very low density lipoproteins, were fed ad libitum or restricted until point of lay. All birds were fed ad libitum after laying an egg, and aspects of growth and reproduction were measured to 40 weeks of age. 2. Compared with lean line birds the growth rate of fat line females fed ad libitum declined from 16 weeks of age. 3. Mortality from apparently stress-related causes in ad libitum fed fat line females increased from 16 weeks of age and was 71% overall, compared with 26% in ad libitum fed lean line females. Mortality in the corresponding restricted birds was 20% and 7%, respectively. 4. Few fat line females fed ad libitum commenced lay and those which were restricted during rearing stopped laying after the initiation of ad libitum feeding. Egg productions in lean line birds fed ad libitum or restricted were similar. 5. Fat line females fed ad libitum had few yellow follicles and a high rate of atresia at first egg and between 37 and 39 weeks, as did restricted fat line birds between 37 and 39 weeks of age after being fed ad libitum. 6. Plasma concentrations of oestradiol-17 beta were 5-fold higher in fat compared with lean line females at 35 weeks of age. There was a similar large difference in concentrations of plasma triglyceride which reached 59 mg/ml in fat line females fed ad libitum.     

Effects of restricted and ad libitum intake of diets containing wheat middlings on site and extent of digestion in steers

A 5 x 5 Latin square design was used to determine the effects of restricted and ad libitum intake of diets containing wheat middlings on the site and extent of digestion compared to ad libitum intake of a corn-based diet and ad libitum intake of chopped alfalfa hay. Five ruminally and duodenally cannulated Angus steers (519 +/- 41.5 kg BW) were used to compare five dietary treatments. The five treatments were as follows: ad libitum access to a corn-based finishing diet (control), the control diet with 25 percentage units of the corn and soybean meal replaced with wheat middlings offered ad libitum (WM), the WM diet restricted to 75% of predicted ad libitum intake (RWM), the RWM diet with wheat middlings replaced with ammoniated wheat middlings (RNWM), and ad libitum access to a chopped alfalfa hay diet. Although RWM steers were fed to consume 75% of ad libitum intake, RWM steers consumed 15.5% less DM than WM. Steers fed ad libitum hay consumed 28.6, 31.7, and 37.2% less (P < 0.01) DM, OM, and nitrogen than RWM steers. No differences in apparent or true ruminal digestibility were observed among steers fed the control vs WM, WM vs RWM, RWM vs RNWM, or RWM vs hay diets. However, the steers fed the hay diet had 32.5, 33.4, and 36.9% lower (P < 0.01) apparent total tract digestibilities of DM, OM, and N than those fed the RWM diet. Average ruminal pH was lower (P < 0.01) for control steers than those fed the WM diet and for those fed RWM compared to the hay diet. The acetate:propionate ratio was higher for cattle fed hay vs the RWM diet. Microbial DM and OM flow to the small intestine was higher (P < 0.02) for steers fed the RWM diet than those fed the hay diet. In addition, bacterial N flow to the small intestine was higher (P < 0.01) for cattle receiving the RWM diet than the hay diet. Feeding diets containing 25 percentage units of wheat middlings at 75% ad libitum intake had no effect on ruminal digestibility.     

Effects of interactions between photostimulation, dietary restriction and dietary maize oil dilution on plasma LH and ovarian and oviduct weights in broiler breeder females during rearing

1. The response of the reproductive system to photostimulation was investigated during the rearing period in dwarf broiler breeder females maintained from hatch on 8 h light/d. The effect of increased body fat on this response was investigated. Body fat was increased by diluting the diet with maize oil. 2. A significant increase in plasma luteinising hormone (LH) was observed 4 d after photostimulation with 20 h light/d at 3 and 15 weeks of age in birds fed the restricted diet alone and at 3, 7, 11, 15 and 19 weeks of age in birds fed the restricted diet diluted with maize oil. 3. Increases in ovarian weight were observed two weeks after photostimulation at 15 weeks of age in birds fed the restricted diet alone and at 7, 11 and 15 weeks of age in birds fed the restricted diet diluted with maize oil. Increases in oviduct weight were seen after photostimulation at 11, 15 and 19 weeks of age in both dietary treatment groups; however, a larger increase in oviduct weight was seen at 15 and 19 weeks of age in birds fed the restricted diet diluted with maize oil. 4. In a second experiment, the dilution of a diet fed ad libitum with maize oil significantly increased body fat content and the baseline concentration of LH but did not enhance the response of the reproductive system to photostimulation. 5. Baseline plasma LH concentrations were lower in birds fed ad libitum than in those fed a restricted diet. 6. It is concluded that the neuroendocrine pathways involved in the transmission of photoperiodic information are functional at 3 weeks of age. The function of the components of the hypothalamo-pituitary complex which control reproductive activity is enhanced when a restricted diet diluted with maize oil is fed.     

Effects of low dietary protein and different allocations of food during rearing and restricted feeding after peak rate of lay on egg production,fertility and hatchability in female broiler breeders

1. A 3x2x2 factorial experiment was conducted with boiler breeder females to determine the effects of body weight gain (three levels) and conventional or lower crude protein concentrations in the rations during rearing, and restricted or ad libitum feeding after the peak rate of lay on egg production, fertility, hatchability, mortality and food consumption. 2. Compared with ad libitum feeding, conventional food restriction resulted in a decrease in average daily food consumption of 0.6 during rearing, 0.2 during early lay and an increase of 0.4 after the peak rate of egg production. Mortality was decreased by more than half. 3. Restricted birds had higher total and settable egg production, fewer defective or damaged eggshells and higher fertility and hatchability than those fed ad libitum. The modified (more generous) rearing programme resulted in lower rates of egg production and higher rates of mortality compared with the conventional food restriction programme. 4. Low-protein rearing rations were associated with higher rates of food intake, higher mortalities and lower rates of egg production than the conventional protein rations. There were no differences in the fertility or hatchability of eggs between birds fed on the two concentrations of dietary crude protein. 5. Ad libitum feeding post-peak was associated with higher rates of mortality to 60 weeks of age. Post-peak feeding had little effect on the rate of lay or egg weight in conventionally restricted birds fed high protein rations or in birds fed ad libitum. Restricted feeding post-peak decreased the rate of lay and egg weight in birds on the modified restriction programme and in conventionally restricted birds fed on the low protein rations. There was no effect of post-peak feeding on fertility or hatchability of eggs. 6. The total numbers of saleable chicks per kg food consumed were 1.83, 1.72 and 0.52 for conventional, modified and ad libitum feeding during rearing; 1.56 and 1.15 for restricted and ad libitum feeding post-peak: there were no differences associated with protein concentrations of rations fed during rearing.     

The efficiency of nitrogen retention during compensatory growth of food-restricted broilers

1. Two experiments were conducted to investigate the influence of compensatory growth, induced by early quantitative food restrictions, on the efficiency of nitrogen-retention in two lines of Ross broilers. 2 . Birds were restricted to 80% of the ad libitum intake of the previous 24 h of the control group from d 4 to d 7. After the period of restrictions all birds were fed ad libitum . 3 . In both trials, the final body weight of the restricted Ross 208(308) birds was similar or even higher than that of the control group. For the Ross 508 line, compensatory growth was substantial in the first trial, but non-existent in the second trial. In all cases, the mortality of restricted birds was lower than in control birds. 4. Not only environmental factors, but mainly chick quality, seemed to have a major influence on the capacity of the chickens to establish compensatory growth. 5. As compensatory growth was established, some improvement in N retention was induced. Although differences were not significant, they may be environmentally important. 6. It is concluded that a retardation of the early growth of fast growing broiler chickens can, in certain circumstances, reduce mortality and increase performance and N retention.     

Reproductive performance of dwarf broiler breeders given different allowances of food during the rearing and breeding periods and two lighting patterns

1. Dwarf broiler breeders were either fed ad libitum or restricted to allow growth to mean body weights of 1.4 or 1.8 kg at 20 weeks of age. During the breeding period these birds were fed ad libitum, or food was restricted to different degrees and the birds subjected to two different incremental lighting patterns. 2. Egg production of birds fed ad libitum during the breeding period increased with the degree of food restriction during rearing. 3. Food restriction during the breeding period increased the egg production of birds weighing 1.8 kg at 20 weeks but decreased that of birds weighing only 1.4 kg. 4. Fertility was relatively low and inversely related to body fatness of females. 5. The differences in lighting pattern did not influence performance. 6. For optimum reproductive performance during the rearing period dwarfs should not be restricted so severely as conventional breeders. Best chick production was obtained from birds with a bodyweight of 1.8 kg at 20 weeks of age, which were subjected to a 10% restriction of food during the breeding period.     

Early and temporary quantitative food restriction of broiler chickens. 1. Effects on performance characteristics, mortality and meat quality

1. An experiment was conducted with broiler chickens to determine the effects of different early food restrictions, strain (Ross 508 and Hybro G) and sex on performance, mortality carcase composition and meat characteristics. 2. Birds were restricted to 80% or 90% of ad libitum intake for 4 d (80%-4 d-group and 90%-4 d-group, respectively) or 80% for 8 d (80%-8 d-group). All restrictions started on d 4. After the periods of restriction, all birds were fed ad libitum. 3. Only the 90%-4 d-group reached a final body weight not significantly different from, but lower than, the ad libitum group. The other restrictions were too severe to allow a sufficient 'catch-up'. 4. No significant differences in food conversion and total carcase fat content between groups were observed. Abdominal fat showed a tendency to increase due to the restrictions induced. 5. There was a slight trend towards a reduced mortality and of 'sudden death syndrome' but no clear effect of food restriction on number of chickens removed with leg problems. There was no significant decrease in uniformity of the flocks due to restriction. 6. The group 80%-8 d had a significant lower yield percentage. Cut-up parts and meat quality were not changed by restriction. Ross birds had a significantly higher proportion of breast meat than Hybro chickens. Meat of female chickens seemed to be paler than that of males, possibly because of the higher proportion of carcase fat. 7. Food restriction did not always give good results. However, a mild restriction (90% for 4 d) may offer some economic advantages over an ad libitum feeding regimen, mainly by reducing mortality.     

Sensorial quality and bone strength of female and male broiler chickens are influenced by weight and growth rate

1. An experiment was conducted with 98 male and 98 female broiler chickens (Ross 308) to study the effect of growth rate, induced by different dietary means, sex and live weight (1500?g and 2000?g) at slaughter on production parameters, bone strength and sensorial characteristics of the breast meat.

2. The birds were divided into four groups and individually fed a standard commercial diet, a high energy diet or low energy diet from d?11 to slaughter at between d 28 and 39. Three groups were fed ad libitum and a further group was fed a restricted amount of the high energy feed. Half of the birds in each group were slaughtered at approximately 1500?g and the other half at 2000?g live weight.

3. The diets resulted in different growth rates. The chickens fed the high energy and the commercial diet had the highest growth rate at both live weights at slaughter. The restricted fed chickens had lower bone strength than the chickens fed the low energy diet.

4. Breast meat from male broilers was juicer, more tender and less hard than breast meat from females. Chickens slaughtered at 2000?g live weight were juicer than those slaughtered at 1500?g. Chickens given the high energy feed ad libitum and restricted had different growth rates, but the sensory parameter related to texture showed no difference.

5. It was concluded that an increased slaughter weight might improve meat quality due to improved juiciness.     

Effect of infectious bursal disease virus insult on iron, copper, and zinc concentration in liver, bursa of Fabricius, spleen, pancreas, and serum of chickens

The effect of a systemic disease on the dynamics of iron, zinc, and copper in chickens fed ad libitum was examined by infecting 10-day-old specific pathogen-free chickens with infectious bursal disease virus (IBDV). Liver, bursa of Fabricius, pancreas, spleen, and serum were sampled in 10 controls and 10 challenged chickens at 3-day intervals postinfection (PI) for 15 days. The samples were analyzed using atomic absorption spectroscopy. Serum levels were similar to that reported in the literature. Concentrations of iron and zinc did not change significantly in the pancreas, but there was an increase in copper in infected pancreatic tissue on days 9 and 15 PI. Iron concentration in the spleen showed a significant increase on days 6, 9, and 15 PI, whereas zinc was only significantly increased on day 15 PI. There was no significant change in copper concentrations in the spleens of infected chickens vs. controls. This finding is in line with previously reported data. The results showed that the liver was not a major tissue where iron and zinc were sequestered, as previous data have shown in mammals. Instead, the bursa of Fabricius had significantly increased levels of both iron and zinc in infected tissue vs. control tissue from 9 days PI on. Furthermore, the bursa had increased levels of copper in the latter portion of the study. These findings suggest that the bursa of Fabricius rather than the liver is the major organ for metallic ion sequestering during IBDV infection.     

Effects of feeding growing cattle high-concentrate diets at a restricted intake on feedlot performance

Three trials were conducted to compare effects of restricted intake of high-concentrate diets vs ad libitum intake of corn silage diets during the growing phase on feedlot cattle performance. In Trial 1, 120 steers (initial BW, 246 kg) were fed 1) a corn silage-based diet ad libitum, 2) a high-moisture corn-corn silage-based diet with intake restricted to a level 20% less than that of the corn silage diet or 3) a high-moisture corn-based diet with intake restricted to a level 30% less than that of the corn silage diet. Steers fed the 20% restricted corn-corn silage-based diet tended (P = .07) to gain slower than those fed the corn silage or 30% restricted high-concentrate diet. Feed efficiency and diet digestibility were greatest for steers fed the 30% restricted-intake, high-concentrate diet (P less than .01). Performance of steers during the subsequent 118-d finishing period was not affected (P greater than .65) by source of energy during the growing period. In Trial 2, ADG of steers fed the 30% intake-restricted, high-concentrate diet was lower (P less than .01) than that of steers with ad libitum access to corn silage. During the 84-d growing period, steers fed supplemental blood meal had 8.3% greater gains and a 6% greater efficiency of feed use than those fed supplemental soybean meal (P less than .01). Monensin did not affect (P = .82) performance of steers fed 30% restricted-intake diets. During the 76-d finishing period, gains and feed conversion were improved (P less than .01) for steers fed the restricted-intake diet in the growing period compared with those given ad libitum access to corn silage. During the growing period in Trial 3, ADG of steers restricted-fed an all-concentrate diet were slightly greater (P less than .10) than ADG of those given ad libitum access to corn silage. Gains did not differ (P = .37) during the subsequent finishing period when steers were switched to 85 or 100% concentrate diets. We concluded that intake of all concentrate diets can be restricted to achieve gains equal to those of steers given ad libitum access to corn silage-based diets without detrimental effects on finishing performance.     

Digestibility of pentose sugars and uronic acids and their effect on chick weight gain and caecal size

1. In the first experiment D-xylose, L-arabinose, D-galacturonic and D-glucuronic acids were fed ad libitum to young chicks for 2 weeks at 200 g/kg of diet and weight gains and food consumption were recorded. 2. L-arabinose and D-xylose did not depress food consumption in the first week but prolonged feeding caused food consumption to decrease and weight gain to be adversely affected. 3. D-galacturonic acid and D-glucuronic acid caused severe growth retardation as early as the first week of feeding, primarily because of voluntary starvation. 4. Apparent metabolisable energy values for the diets were obtained when chicks were 19 to 21 d of age and were 14.04 +/- 0.52, 12.03 +/- 0.61, 11.77 +/- 1.21, 11.68 +/- 0.34 and 11.66 +/- 0.45 KJ/g for the basal diet with glucose, xylose, arabinose, galacturonic and glucuronic acids respectively. 5. True metabolisable energy values for the diets were obtained from adult cockerels and were 15.07 +/- 0.16, 13.45 +/- 0.16, 13.12 +/- 0.37, 12.29 +/- 0.26 and 12.69 +/- 0.23 KJ/g for basal diet with glucose, xylose, arabinose, galacturonic and glucuronic acids respectively. 6. In the second experiment D-galactose, D-xylose, L-arabinose, D-galacturonic and D-glucuronic acid were fed ad libitum to young chicks for 3 weeks at 50 g/kg of diet and weight gains and food consumption were recorded. 7. Chicks grew and ate well on all diets. 8. The digestibilities of sugars and uronic acids were obtained by measurement of these constituents in diets and digesta using titanium dioxide as a marker. The digestibilities were 1.000 +/- 0.0, 0.997 +/- 0.002, 0.936 +/- 0.041, 0.628 +/- 0.103, 0.588 +/- 0.059, and 0.645 +/- 0.089 for D-glucose, D-galactose, D-xylose, L-arabinose, D-galacturonic and D-glucuronic acids respectively. 9. Both at 200 and 50 g/kg dietary inclusion there was noticeable caecal fermentation from L-arabinose, D-galacturonic and D-glucuronic acid. Only at 200 g/kg dietary inclusion did D-xylose produce significant evidence of caecal fermentation.