Performance, serum characteristics, carcase traits and lipid metabolism of broilers as affected by supplement of chromium picolinate.

1. This study investigated the effects of dietary supplementation with chromium picolinate on the performance, serum and carcase traits and lipid metabolism of broilers. In trial 1, 120 1-day-old broilers with an equal number of males and females were assigned at random to 4 groups with 3 replicates. Four treatments with dietary supplements of 0 (control), 800, 1600 and 3200 microg/kg of chromium picolinate were used. In trial 2, 6-week-old broilers (20) were used to determine how supplements of 0, 200, 400 and 800 microg/kg chromium in an incubation medium influence their hepatocyte lipogenic capacity and adipocyte lipolysis, in vitro. 2. Dietary supplements of 1600 and 3200 microg/kg chromium in broiler diets significantly increased food consumption (P<0.05); 1600 microg/kg markedly improved weight gain (P<0.05); 1600 and 3200 microg/kg groups showed increased liver lipid content (P<0.05). However, the abdominal fat content tended to decrease in these 2 groups. 3. Dietary supplements of 1600 and 3200 microg/kg of chromium decreased serum glucose and nonesterified fatty acids (NEFA) concentrations while increasing serum phospholipid content (P<0.05). Insulin concentration decreased only in birds receiving 3200 ppb chromium (P<0.05). Serum triacylglycerol (TG) clearance rate in chromium-supplemented groups was markedly enhanced (P<0.05). 4. In addition, chromium supplemented groups had increased serum HDL contents and also reduced serum VLDL and LDL contents (P<0.05). 5. Trial 2 indicated that lipogenesis from [U-14C]glucose by isolated hepatocytes was significantly enhanced by 400 ppb chromium (P<0.05). 6. The results from this study demonstrate that a supplement of 1600 microg/kg of chromium picolinate in the ration influences the growth, carcase, serum traits and lipid metabolism of broilers.     

Growth and carcass traits of heifers as affected by hormonal treatment

Seventy-seven heifers weighing about 200 kg were assigned randomly to intact control (C), ovariectomized (OVX) immunized against estradiol (BSA-E), BSA-E + trenbolone acetate (BSA-E + TBA), TBA or ovx + TBA groups. The objective of the study was to determine the effects of ovariectomy, immunoneutralization of estradiol and trenbolone acetate treatment on growth rate and carcass merit. Heifers were fed a corn-corn silage diet and were slaughtered when treatment groups attained live-animal weights of 433 kg. Observations of rate of growth, efficiency of feed conversion, characteristics of carcasses and characteristics of organoleptic properties of the cooked meat were made. Average daily gains (ADG) were similar in the control and OVX groups and tended to be less than in other treatment groups (P less than .36). Although not statistically significant, the observed mean for the BSA-E + TBA treatment suggests improved ADG and TDN per unit of gain, indicating a possible immunization X TBA interaction. Data also suggested that heifers implanted with TBA had increased ADG and efficiencies of gain. Possibly, immunoneutralization of endogenous estradiol can improve ADG as compared with control and OVX groups. Treatments had no effect on color or texture of lean muscle at the 12th rib interface. The OVX + TBA group had less (P less than .01) 12th rib fat cover than other groups and lower percent fat in the rib than C. The BSA-E + TBA and TBA groups also possessed larger (P less than .02) longissimus muscle areas than the control group. Observations of juiciness, tenderness and flavor were similar among all treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comb lesions and mortality patterns in white leghorn layers affected by Marek's disease

Marek's disease was diagnosed as the cause of prolonged high mortality in two commercial flocks of white leghorn layers by gross and microscopic examination of affected tissues and by immunofluorescent study of live tumor cells using anti-Marek's disease tumor-associated surface antigen, anti-immunoglobulin M, and monoclonal antibodies. The disease was characterized by swollen, necrotic, lymphomatous combs and mortality that rose above normal at 28 weeks of age, peaked at 35-36 weeks, and returned to normal by 45-46 weeks.     

有机铬对热应激蛋鸡生产性能和血液生化指标的影响

试验选用91周龄新罗曼商品蛋鸡480只,按2×2双因子试验设计随机分为5组,对照组饲喂不添加铬的玉米-豆粕型基础日粮,4个试验组饲喂在基础日粮中分别添加了以吡啶羧酸铬或酵母铬来源的0.2mg/kg或0.4mg/kg的日粮,试验30d,以研究有机铬对热应激蛋鸡生产性能和血液生化指标的影响。试验结果显示:①有机铬能在一定程度上促进热应激蛋鸡的蛋白质利用,提高热应激蛋鸡的生产性能;②铬水平对血清尿素氮有极显著的影响(P<0.01),添加0.4mg/kg铬组均极显著地低于对照组(P<0.01),说明了补铬能够抑制由高温引起的蛋白质分解过程,从而起到缓解高温应激的作用;③吡啶羧酸铬和酵母铬在作用效果上无显著的差异;从经济效益方面考虑,0.4mg/kg铬水平的酵母铬和吡啶羧酸铬经济效益较高。     

Nitrogen efficiency of dairy cows as affected by diet and milk yield

The aim of this study, which was part of the EU-financed project Life Ammonia, was to evaluate the effects of dietary components and milk production on nitrogen efficiency of dairy cows. The study included examining the effects of decreased crude protein (CP) concentration in a grass-clover silage based diet and results of mixing whole-crop barley silage (WCBS) with grass-clover silage in the diet, on feed intake, milk production and nitrogen efficiency. Rations were formulated and milk production data were registered individually each month for 42 cows of the Swedish Red Cattle breed during four indoor periods from 1999 to 2003. The range in nitrogen efficiency by the cows, 11 to 398 days in milk, was 18 to 40%, when fed a diet containing 135 to 184 g CP/kg DM, 44 to 56% of NDF as rumen degradable fibre (RDF) and milking 13 to 57 kg of ECM daily. The average CP concentration of the diet, containing mainly grass-clover silage and concentrate, was decreased from 168 g/kg DM (170 g in early lactation) in the control treatment period to 160 g/kg DM (163 g in early lactation) during the following treatment period. The CP concentration was 170 g/kg DM (171 g in early lactation) during the third treatment period, when the grass-clover silage was fed in a mixture with WCBS. Using the whole data set (n = 284 for primiparous, n = 440 for multiparous cows based on measurements each month) resulted in models, in which total DM intake, ECM yield, dietary CP concentration and RDF were the most important factors affecting nitrogen utilisation of primiparous and multiparous cows. Increases in both average DM intake and milk yield by multiparous cows and no changes in average intake and milk yield by primiparous cows fed the low CP diet or the normal CP diet containing WCBS, compared to cows fed the normal CP diet, resulted in similar nitrogen efficiencies among the treatments. Hence, dietary CP concentrations of 160 to 170 g/kg DM can be used for cows in early lactation in commercial herds to improve nitrogen utilisation without causing a simultaneous decrease in milk yield.     

Effects of age and diet on the lipid content and composition of gallbladder bile, liver and serum in laying strains of hen

1. Changes in lipid content and composition of liver and bile during pre- and post-laying periods were investigated in hens of a laying strain. 2. The large increase in liver lipid concentration, particularly triacylglycerols, at the onset of laying was accompanied by the appearance of triacylglycerols in the bile. 3. Accumulation of triacylglycerol in the liver was increased by a diet containing maize and soyabean meal. This was associated with increases in the triacylglycerol concentration in both serum and bile. 4. Liver microsomal phosphatidate phosphohydrolase activity was positively correlated with liver triacylglycerol content in birds given the maize/soyabean meal diet. 5. The time course of triacylglycerol accumulation in the liver and associated changes in the bile triacylglycerol concentration in laying strain hens were different to those previously observed in broiler hens. 6. Over the lifetime of the bird, secretion of triacylglycerols into bile may play an important role in the prevention of fatty liver syndromes.     

大肠杆菌O126免疫产蛋鸡后血清抗体与卵黄抗体效价动态变化规律比较

由引起婴幼儿腹泻的主要致病菌大肠杆菌Ｏ１２６免疫产蛋鸡，提取血清抗体与卵黄抗体，结果，血清抗体与卵黄抗体的动态变化规律基本相似，二者变化曲线基本吻合。实验认为可以直接提取卵黄抗体用于制备预防婴幼儿腹泻的口服液。     

Glucose clearance in grazing mares is affected by diet,pregnancy, and lactation

The glucose tolerance test in the horse may be used to determine metabolic responses to diet, disease, or physiologic state. The objective of this study was to determine the effect of reproductive stage (gestation and lactation) and supplemental dietary energy source (sugar and starch [SS] or fiber and fat [FF]) on glucose metabolism in grazing mares using an oral glucose tolerance test. Twelve mares, six on each supplement, were examined on three occasions: one in the third trimester of pregnancy, the second in early lactation, and the third in late lactation. During each test, venous samples were taken at 30 and 1 min before, and 30, 60, 90, 120, 150, 180, 240, and 300 min after a nasogastric dose of glucose at 0.2 g/kg of BW. Plasma was assayed for glucose, insulin, and cortisol. Statistical analysis was a mixed model with repeated measures with horse, diet, and reproductive stage as fixed effects. The incremental glucose area under the curve (AUC) in response to oral glucose was lower in SS than in FF mares (P = 0.022). Mares tended to have a lower incremental glucose AUC in early lactation than in late gestation (P = 0.057), and insulin AUC was lower in early lactation than in late gestation (P = 0.002) and late lactation (P = 0.013). Glucose clearance was more rapid (P = 0.007) in SS than in FF mares. The glycemic response to the oral glucose tolerance test was consistent with adaptation to dietary sugar and starch as well as metabolic changes associated with pregnancy and lactation. Feeding twice-daily grain meals rich in SS influenced glucose metabolism in horses to an extent that the natural adaptation of glucose metabolism to pregnancy was moderated. Feeding a diet rich in FF more closely mimics the natural grazing state of pasture and allows for adaptation of glucose metabolism to pregnancy and lactation.     

Growth and tiller production of Themeda triandra as affected by NPK fertilisation

Themeda triandra Forssk. is a common perennial grass in southern African grasslands that tolerates low nutrient soils. Establishment of the species into degraded or transformed areas is difficult, but there have been some advances with clonal propagation using tillers. To generate propagules (tillers), tiller production of plants must be maximised. This research focused on the growth response of T. triandra to fertilisation with nitrogen (N), phosphorus (P), and potassium (K) each at three levels in a fully factorial pot experiment. Fertilisation increased growth. The number of tillers and aerial shoot mass were controlled by an N × P interaction, and total mass and root mass were controlled by N and by P, with N having a larger effect. Mass per tiller was not related to treatment. Shoot:root ratio and root mass per tiller were controlled by N. Potassium had no effect on any response. For maximum tiller production of T. triandra, plants should be fertilised with high levels of N and P.     

Digestibility and absorption of nutrients as affected by fibre content in the diet of the pig. Quantitative aspects

An attempt has been made to assess some quantitative aspects of the influence of fibre content in feedstuffs and diets on the digestibility and absorption of nutrients in pigs. The study is based on selected published literature and data from Danish experiments.The digestibility of nutrients consistently decreases with increasing fibre content in the diet, regardless of the analytical method used. However, the magnitude of this negative influence depends on the type and origin of the fibre source, technical treatment, feeding level, age and live weight of the pigs, etc.Increasing the content of crude fibre in diets is related to increasing the content of less digestible carbohydrate (hemicellulose) and a concurrent decrease in the content of easily digestible substances. It is shown that for each 1% increase in the crude fibre content, the content of starch + sugars in the NFE-fraction is decreased by 2.1–2.7%. This results in a reduced ileal digestibility, enhanced fermentation in the hindgut and an overall reduction of the digestibility of gross energy.Experimental data from this institute comprising 246 diets and 257 single feedstuffs were used to generate equations for prediction of the digestibility of gross energy. A single carbohydrate fraction (NDF or crude fibre) alone accounted for about 70% of the variation in digestibility in diets and 85% of the variation in digestibility of single feedstuffs.Fibre determination values based on either detergent methods (NDF) or crude fibre analysis supplemented with enzymic determination of starch + sugars were equally good as predictors of the digestibility of gross energy.     

Effects of dietary copper on production and egg cholesterol content in laying hens

1. This experiment was carried out to determine the effects of diets supplemented with different amounts of copper on egg production, food intake, food conversion ratio, egg weight, damaged egg ratio, specific gravity, mortality and cholesterol concentration in yolk. The experiment lasted 90 d and 400 Hisex-Brown hens, aged 27 weeks at the start of the study, were used. 2. There were no statistically significant effects of supplementary copper on egg production, food intake or food conversion efficiency. 3. There were no statistically significant differences between the groups in terms of damaged eggs, egg weight, specific gravity and live weight. 4. At the end of the experiment, the lowest yolk cholesterol concentrations were obtained in the 150 kg/kg copper group and the greatest concentrations were in the control group. 5. Consequently, the use of supplementary copper to provide 150 kg/kg in poultry diets was concluded to decrease yolk cholesterol concentrations without any effect on production performance.     

Correlation analysis of the total IgY level in hen serum,egg yolk and offspring serum

The correlation between IgY levels of the serum and the yolk has been well documented in wild and domestic birds. The levels of total yolk IgY can be an index of the general health status of birds and may contribute to breeding programs when fitness of the offspring is a concern. We measured the levels of total serum IgY and yolk IgY in three different breeds （White Leghorn, Silkie and Dongxiang blue-shell） using indirect ELISA, and found that there was a significantly positive correlation between the levels of total serum IgY and total yolk IgY in all three breeds （White Leghorn： r = 0.404, P 〈 0.001, n = 100; Silkie： r = 0.561, P 〈 0.001, n = 70; Dongxiang blue-shell： r = 0.619, P 〈 0.001, n = 30）. We also measured the total serum IgY levels in the 3-day-old offspring hatched from the Silkie hens and results were significantly correlated for serum IgY levels （r = 0.535, P 〈 0.001, n = 70） and the yolk IgY levels （r = 0.481, P 〈 0.001, n = 70）. The regression analysis showed simple linear regression between IgY levels in hen serum, yolk and offspring serum. Our results suggest that total IgY level could be used as an index for chicken fitness.     

Correlation analysis of the total IgY level in hen serum,egg yolk and offspring serum

The correlation between IgY levels of the serum and the yolk has been well documented in wild and domestic birds. The levels of total yolk IgY can be an index of the general health status of birds and may contribute to breeding programs when fitness of the offspring is a concern. We measured the levels of total serum IgY and yolk IgY in three different breeds (White Leghorn, Silkie and Dongxiang blue-shell) using indirect ELISA, and found that there was a significantly positive correlation between the levels of total serum IgY and total yolk IgY in all three breeds (White Leghorn: r = 0.404, P < 0.001, n = 100; Silkie: r = 0.561, P < 0.001, n = 70; Dongxiang blue-shell: r = 0.619, P < 0.001, n = 30). We also measured the total serum IgY levels in the 3-day-old offspring hatched from the Silkie hens and results were significantly correlated for serum IgY levels (r = 0.535, P < 0.001, n = 70) and the yolk IgY levels (r = 0.481, P < 0.001, n = 70). The regression analysis showed simple linear regression between IgY levels in hen serum, yolk and offspring serum. Our results suggest that total IgY level could be used as an index for chicken fitness.