Individual and combined effects of t‐2 toxin and das in laying hens

1. The individual and combined effects of T‐2 toxin and 4,15‐diacetoxyscirpenol (DAS) on laying hens were investigated in an experiment consisting of a 2 X 2 completely randomised factorial design with dietary concentrations of 0 and 2 mg/kg T‐2 toxin and 0 and 2 mg/kg DAS.

2. Individually, T‐2 toxin and DAS induced oral lesions in half of the hens and decreased significantly egg production and food intake.

3. The effects of T‐2 toxin and DAS were additive for reduced food consumption and incidence of oral lesions. However, a synergism for reduced egg production was observed during the last experimental period.

4. No effects on body weight were observed during this study. Mild changes in selected plasma enzymes activities and no change in liver malondialde‐hyde content were detected.

5. The combination of T‐2 toxin and DAS was more toxic than the single mycotoxins, for some parameters, and therefore, may pose a greater economic threat to the poultry industry than either of the toxins individually.     

Effects associated with the pea‐comb gene on chick weight,and body weight and food efficiency of adult hens

1. Growth rate, laying traits, food intake and food conversion efficiency of laying hens were compared in several experiments on pairs of full or half sibs one of which was a pea‐comb bird (Pp), the other single‐comb (pp).

2. There was a slight but significant depressing effect associated with the Pp genotype on 8‐week weight of chicks and body weight of laying hens in some populations.

3. Pea‐comb hens showed a reduction of about 2% in food consumption, independent of the effects on body weight and egg production, and we suggest that with the smaller size of comb and wattles for Pp hens, heat losses and hence energy requirements are less.

4. Appetite seemed to be more depressed at high ambient temperature in birds of the Pp genotype.     

Ovarian morphology and rates of ovarian follicular development in laying broiler breeders and commercial egg‐producing hens

1. Ovaries from a light‐bodied egg laying strain and a broiler breeder strain were compared at 26 and 82 weeks of age.

2. The rate of lay in both strains was lower in the older hens. The 82‐week‐old hens were subdivided into good and poor layers: the poor layers produced eggs at about half the rate of the good layers.

3. The yellow‐yolky ovarian follicles in both strains were smaller, more numerous and more closely ranked in hierarchies in 26‐week‐old hens than in 82‐week‐old hens.

4. No marked differences were seen between the strains at 26 or 82 weeks of age in the sizes, numbers or hierarchical arrangements of yellow‐yolky ovarian follicles.

5. The ovaries from 82‐week‐old good and poor layers from both strains contained similar numbers of yellow‐yolky follicles.

6. After feeding a fat‐soluble dye, the number of days over which eggs containing dye were laid did not differ between 26‐, 52‐ and 113‐week‐old hens from an egg laying strain. However, fewer eggs with dyed yolks were laid by the older hens.

7. These observations suggest that the decrease in egg production with age is due initially to a reduction in the rate of recruitment of yellow‐yolky follicles. Towards the end of the laying year it may also be due to an increased incidence of follicular atresia, internal ovulation and the production of membraneous or soft shelled eggs.     

H/L ratio as a measurement of stress in laying hens – methodology and reliability

1. Measuring the ratio of heterophils and lymphocytes (H/L) in response to different stressors is a standard tool for assessing long-term stress in laying hens but detailed information on the reliability of measurements, measurement techniques and methods, and absolute cell counts is often lacking.

2. Laying hens offered different sites of the nest boxes at different ages were compared in a two-treatment crossover experiment to provide detailed information on the procedure for measuring and the difficulties in the interpretation of H/L ratios in commercial conditions.

3. H/L ratios were pen-specific and depended on the age and aviary system. There was no effect for the position of the nest. Heterophiles and lymphocytes were not correlated within individuals. Absolute cell counts differed in the number of heterophiles and lymphocytes and H/L ratios, whereas absolute leucocyte counts between individuals were similar. The reliability of the method using relative cell counts was good, yielding a correlation coefficient between double counts of r > 0.9.

4. It was concluded that population-based reference values may not be sensitive enough to detect individual stress reactions and that the H/L ratio as an indicator of stress under commercial conditions may not be useful because of confounding factors and that other, non-invasive, measurements should be adopted.

     

Feeding value of rice distiller’s dried grains with solubles as protein supplement in diet of laying hens

A feeding trial of 10 weeks duration was undertaken on laying hens (n = 240) to evaluate feeding value of rice distiller’s dried grains with soluble (rDDGS) with or without enzyme supplementation (α-amylase, β-glucanase, xylanase, carboxymethylcellulase, pectinase, proteinase, α-galactosidase, β-galactosidase, lipase, and phytase), following 4 × 2 factorial design, on egg production, nutrient utilization, and cost economics of egg production. The birds were randomly assigned to eight dietary treatments with 30 birds/treatment. The birds were housed individually in layer cages and each bird was taken as an experimental unit. Eight experimental diets were prepared by incorporating four levels (0, 50, 75, and 100 g/kg) of rDDGS with and without enzyme supplementation. The results revealed a significant (P < 0.01) increase of egg mass, feed intake, egg production, and body weight gain in dietary treatments with up to 75 g rDDGS though the values were statistically similar to the hens fed 100 g rDDGS. Enzyme supplementation resulted in significant (P < 0.01) improvement of egg mass, egg production, feed conversion ratio (FCR) per dozen eggs, FCR per kilogramme egg mass, and net FCR. The significantly (P < 0.01) higher yolk index was observed at 100 g rDDGS level, while shell thickness improved significantly (P < 0.01) up to 75 g rDDGS level. No significant effect of rDDGS inclusion was observed on shape index, albumin index, and Haugh unit. Enzyme supplementation significantly improved the shell thickness and yolk colour of eggs. Nitrogen, calcium, and phosphorus retention and dry matter metabolizability did not show any significant treatment effects. There was significant (P < 0.01) reduction in feed-cost per kilogramme egg mass or per dozen eggs with the increased DDGS levels and dietary enzyme supplementation. It was concluded that rDDGS can be used up to 100 g/kg diet of laying hens along with enzyme supplementation for better productivity of layer hens.

     

Do stocking rate and a simple run management practice influence the infection of laying hens with gastrointestinal helminths?

The aim of this experiment conducted at four sites in Switzerland was to investigate the transmission and infectivity of the two main helminth parasite species of poultry (Ascaridia galli and Heterakis gallinarum) in outdoor runs with two different stocking rates. Additionally, the influence of a simple management practice (mowing of run) on helminth transmission was studied. Three run types were created on each site: runs C served as control (stocking rate 10 m²/hen, no management), runs B corresponded to runs C but were managed (10 m²/hen, management). In runs A stocking rates were doubled compared to control runs (5 m²/hen, no management). During two subsequent layer flocks, a set of parasitological parameters (faecal egg counts (FECs), prevalence, worm burdens in hens and in tracer animals, helminth eggs in soil) as well as parameters describing the run vegetation were determined. The increased stocking rate (runs A) led to a larger proportion of bare soil and to a reduction of the average vegetation height. In runs with a lower stocking rate (B and C), the proportion of bare soil did not increase during the experimental period. Irrespective of the run type, numbers of helminth eggs in the soil decreased significantly with an increasing distance to the hen houses, while the percentage of ground coverage as well as vegetation height increased. However, across runs the correlation between the percentage of ground cover and the values of eggs per gram soil between runs was very low (r² = 0.0007, P = 0.95) indicating a non-causal relationship. Significant differences in FEC were found in flock 2 (P < 0.001): FEC of hens in managed runs B were 24% lower (P < 0.05) than those of the control animals. Although not significant, the corresponding prevalence was lower (−9.7%) in hens from managed runs as well. Hens from runs with a high stocking rate (A) had significantly higher FEC than hens from control runs (C). In flock 2 management (n.s.) and higher stocking rates (−62%, P < 0.05) decreased the worm burdens. Tracer animals from runs with a high stocking rate (A) had significantly higher FEC than tracers from runs B and C in two tracer series. This was not reflected in the worm burdens. Overall, the stocking rate of hens in the outdoor run seemed not to influence the transmission patterns of A. galli and H. gallinarum and repeated mowing of runs did not reduce helminth infections. Lower stocking rates, however, led to a substantial improvement of the run vegetation.     

Effects of group size on performance,health and birds’ use of facilities in furnished cages for laying hens

A total of 1584 Lohmann Selected Leghorn hens were kept in 144 modified cages furnished with—perch, nest and sandbath for 5, 6, 7 or 8 hens per cage or in 162 conventional cages for 4 hens. Cage floor area was 600 cm² per hen excluding nest and sandbath. Doors to nests and sandbaths were time monitored. Production, mortality, exterior egg quality, health, integument and the birds use of facilities were registered from 20 until 80 weeks. No effects of group size or keeping system on production or mortality were detected, but the furnished cage gave more cracked and less dirty eggs than the conventional cage. Hens in the furnished cage had better plumage condition, less toe pad hyperkeratosis, shorter claws, less rear body wounds and stronger humerus, but dirtier feet than hens in the conventional cage. Hens in the larger group sizes had the dirtiest feet. In the furnished cage, on average, 86% of all eggs were laid in the nests and 0.6% in the sandbaths. The rolling out efficiency from nests was best in the larger group sizes. During night less than 0.5% of the hens stayed in the sandbath and less than 2% stayed in the nest. Average use of perches was 28% during the day and 91% at night. Hens in the small group sizes used the sandbath most. Dust‐bathing behaviour also occurred on the wire floor.     

Cloning,expression, and polymorphism at the 5ʹ-flanking region of the GnRH gene and their association with laying traits in Muscovy duck (Cairina moschata)

1. Gonadotropin-releasing hormone (GnRH), a neuropeptide, plays a vital role in the hypothalamus–pituitary–gonadal (HPG) axis. In vertebrates, GnRH is crucial for the onset of sexual development and the entire reproductive process. The purpose of this study was to identify genetic factors associated with egg-laying traits of Muscovy ducks.

2. The full-length cDNA (474 bp) of Muscovy duck GnRH was obtained and characterised. It encodes 92 amino acids containing a 1-amino acid signal peptide cleavage site. Phylogenetic analysis revealed that Muscovy duck GnRH has a close relationship with Anas platyrhynchos GnRH.

3. GnRH showed significantly different expression profiles between 4 developmental periods in the hypothalamus, pituitary, and ovary. The expression of GnRH in the laying period (36 weeks) was higher than at other periods in the three tissues. GnRH was widely expressed in 12 examined tissues of nesting and laying Muscovy ducks. In the hypothalamus, pituitary and gonads, the expression of GnRH was higher than in other tissues.

4. In laying Muscovy ducks, the expression of GnRH in the hypothalamus, pituitary, ovary, muscular stomach, pancreas, heart, duodenum and spleen was significantly higher than in nesting dusks. Differences were detected in the liver and glandular stomach between laying ducks and nesting ducks. Differences between the kidney and lung were not significant.

5. In the pituitary, the GnRH and GnRH receptor (GnRHR) genes shared the same expression profiles during 4 time points. Both genes had the highest expression at 36 weeks of age.

6. A mutation (g.206G > A) in the 5?-flanking region was associated with egg-laying performance. Individuals with genotype GG had better egg-laying performance than the individuals with genotype AA. GnRH may be used as a marker gene for laying performance in the Muscovy duck.

     

Metabolisable energy content of rapeseed meal,soyabean meal and white‐flowered peas determined with laying hens and adult cockerels

1. The apparent metabolisable energy (AME) contents of 5 protein‐rich ingredients were determined with laying hens and the true metabolisable energy (TME) with adult cockerels. The test materials consisted of one batch each of winter‐grown high glucosinolate rapeseed meal (HG‐RSM), summer‐grown HG‐RSM, low glucosinolate rapeseed meal (LG‐RSM), soyabean oil meal (SBM) and white‐flowered peas (WFP).

2. In a separate study the endogenous energy losses (EEL) of adult Rhode Island Red (RIR) and adult broiler roosters were measured when given a supply of energy.

3. AME value for RSM tended to be lower for cockerels than for hens, whereas the opposite was noted for SBM and WFP.

4. This study showed that AME of ingredients could be influenced by choice of technique. These differences are accentuated for some ingredients, such as SBM and RSM, although there was no difference in ranking ingredients tested within the AME and TME systems.

5. Assuming that birds are receiving an energy source, the EEL0 per kg metabolic body weight (W0.75) did not differ between adult broiler cockerels and adult Rhode Island Red cockerels.

6. The AME0 values with laying hens for winter HG‐RSM, summer HG‐RSM, LG‐RSM, SBM and WFP were 7.0, 7.6, 8.7, 11.5 and 11.3 kJ/g dry matter. TME0 values with cockerels for the respective ingredients were 8.4, 8.5, 9.5, 12.6 and 13.4 kJ/g dry matter.     

Immunohistochemical expression of interferon-γ in different types of granulomatous lesions associated with bovine paratuberculosis

Animals infected with Mycobacterium avium subsp. paratuberculosis (Map) show a variety of lesions, from focal forms, seen in subclinical stages to diffuse lesions in clinical cases. The purpose of this study was to evaluate the local expression of IFN-γ by immunohistochemistry in relation with the type of lesion in naturally Map-infected cows. The number of immunolabelled cells, −the majority morphologically consistent with lymphocytes-, was higher in focal and diffuse paucibacillary forms than in diffuse multibacillary lesions, where they appeared closely related to epithelioid cells. Diffuse multibacillary lesions had the lowest numbers, but higher than controls, and positive cells were intermingled among the macrophages. The peripheral IFN-γ production was higher in all Map infected cows and a positive correlation was found with the number of immunolabelled cells in the intestine. The findings of this study show that IFN-γ would play a role in the development of the different types of lesions in paratuberculosis, and also points out the importance of adequate sampling of lymphoid tissue containing samples when studying the local immune response in which IFN-γ expression may be involved, especially in cases where focal lesions are present.     

Patterns of cytokine gene expression of naïve and memory T lymphocytes in vivo

Large-scale lymphocyte recirculation occurs only at the level of secondary lymphoid tissue. Cells enter lymph nodes via afferent lymph from the tissue and via arterioles from the blood. They exit only via the efferent duct. Afferent and efferent lymphocytes have distinct phenotypes; afferent lymphocytes have a 'memory' phenotype, being CD62L(-)/CD45RA(-) and expressing high levels of CD2 and CD11a; efferent cells are largely 'na?ve', being CD62L(+)/CD45RA(+) with low levels of CD2 and CD11a. We will show that functionally the efferent lymphocytes, like cells from the blood and spleen, can be activated in vitro only by dendritic cells. However, afferent lymphocytes are less stringent in their activation requirements and can be stimulated by both macrophages and dendritic cells. To explain these functional differences we have developed a multiprobe RNAase protection assay for 13 sheep cytokines (IL-1beta, IL-2, IL-3, IL-4, IL-6, IL-8, IL-10, IL-12, IL-18, GMCSF, IFNgamma, TGFbeta and TNFalpha) and two housekeeping genes (ATPase and GADPH). We have used this assay to measure the constitutive expression of cytokine mRNA in MACS-purified CD4+ and CD8+ T lymphocytes from both lymphoid compartments.     

Effect of dietary γ-aminobutyric acid on laying performance,egg quality,immune activity and endocrine hormone in heat-stressed Roman hens

This study was conducted to evaluate the effect of γ-aminobutyric acid (GABA) on laying performance, egg quality, digestive enzyme activity, hormone level and immune activities in Roman hens under heat stress. Roman hens (320 days old) were fed with 0, 25, 50, 75 and 100 mg/kg GABA, respectively during a 60-day experiment. Compared with control, supplementation of 50 mg/kg GABA improved the laying performance and egg quality by significantly increasing egg production, average egg weight and shell strength (P < 0.05), while decreasing the feed–egg ratio and cholesterol level. Anti-oxidation activity was improved by significantly increasing the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), but decreasing malondialdehyde level in serum (P < 0.05), while significantly increasing the glucose and total protein (TP) level, follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E₂), insulin, triiodothyronine (T₃) and free triiodothyronine (FT₃) levels, and IgG, IgA and complement (C3)activity in serum (P < 0.05). The results indicated that oral GABA improved laying performance and physical condition mainly by modulating hormone secretion, enhancing anti-oxidation and immune activity, and maintaining electrolyte balance. Fifty mg/kg was the optimum level for laying hens under heat stress in the present study.     

Influence of L–threonine supplementation on goblet cell numbers,histological structure and antioxidant enzyme activities of laying hens reared in a hot and humid climate

1. A previous experiment in our laboratory found that L-threonine supplementation at 0·2 and 0·3% increased egg production and the concentration of serum IgG, respectively. The objective of this current trial was to determine if both supplementation levels can positively influence histological structure, goblet cell numbers, or antioxidant enzyme activities.

2. Babcock Brown layers (n?=?576), 40 weeks of age, were allocated to three treatment groups, each of which included 6 replicates of 32 hens. Each group received the same basal diet formulated with maize, peanut meal and crystalline amino acids. L-threonine was added to the basal diet at 0 (control), 0·2, and 0·3%, respectively for 8 weeks. Chemical analysis of the diets for threonine values were 0·47, 0·66 and 0·74 %, respectively.

3. The numbers of goblet cells did not change due to L-threonine supplementation. Also, L-threonine had no affect on the villus height and mucosal thickness. No differences were found due to treatments among groups in the activity of alkaline phosphatase (ALP) in jejunum or ileum. L-threonine supplementation at 0·2% maximised the concentration of superoxide dismutases (SOD) in both serum and liver.

4. In conclusion, L-threonine supplementation had no affect on gut morphology but may have an antioxidant function at 0·2%.     

Effects of gibberellin and its inhibitors on growth and gene expression in Poa pratensis北大核心CSCD

研究了不同浓度的赤霉素及其抑制剂烯效唑和多效唑对草地早熟禾生长及赤霉素相关基因表达的影响,为外源生长调节剂在草坪养护管理中的高效利用提供理论依据。以1/2 Hogland营养液培养的草地早熟禾为材料,随机分成7组,分别施用不同浓度的赤霉素、烯效唑、多效唑,测定根及叶片的生长量、叶绿体分布、叶绿素含量以及赤霉素相关基因的表达量。结果显示：与对照比较,外源烯效唑和多效唑均显著抑制草地早熟禾的伸长生长以及干/鲜重,但提高了根冠比、叶绿素a、叶绿素b及类胡萝卜素含量（P<0.05）;增加了叶肉细胞层数,使叶绿体充满在叶片上下表皮之间的叶肉细胞中;赤霉素合成代谢途径关键酶基因PpKAO、PpKS1、PpGA₃ox、PpGA₂ox表达量显著下调,赤霉素信号转导受体蛋白基因PpGID1显著上调（P<0.05）。外源赤霉素对草地早熟禾的伸长生长具有促进作用,但降低了根、叶的干/鲜重,提高根冠比,显著提高了赤霉素分解基因PpGA₂ox表达量（P<0.05）。总之,烯效唑、多效唑对草地早熟禾生长发育及基因表达的调控作用与赤霉素相反,但无明显浓度效应;在草坪修剪后立即喷施1000倍的烯效唑或多效唑,对减少用工成本,增加草坪观赏性、提高园林绿化中的草坪草管护水平具有重要意义。     

Responses of laying hens to a low‐protein diet supplemented with essential amino acids,l‐glutamic acid and/or intact protein

1. Three sequential experiments, each lasting 8 weeks, were carried out on 576 singly‐caged light hybrids.

2. In experiment 1 egg production was 84% using a conventional control diet, 61% with a basal low‐protein diet, and 79% with the basal diet supplemented with 10 essential amino acids + L‐glutamic acid (GA).

3. In experiment 2 supplementation with lysine and methionine (L + M) alone increased egg production significantly from 54 to 72%, compared with 83% with the conventional diet.

4. In experiment 3 egg production was 55% with the basal diet, 71% with the basal diet + L + M, 75% with a diet containing 141 g protein/kg + L + M, and 73% with the conventional diet.

5. In all three experiments supplementation with GA alone either gave no significant response or a depression in production.

6. Daily intakes of 1.24 g nitrogen as non‐essential amino acids and 13 to 14 g total crude protein per bird resulted in good egg production. Supplementation of the basal diet with L + M resulted in a daily intake of 413 mg methionine/bird day which was considered adequate, and a daily intake of 710 mg lysine which was considered slightly inadequate.     

Ovarian morphology and internal vis-à-vis non internal laying in relation to triacylglycerol,hormones and their receptors concentration around the age of sexual maturity in broiler breeder hens

1. Ovarian morphology, serum hormone concentrations of 17-β-estradiol, progesterone, testosterone, tri-iodothyronine (T3), thyroxine (T4) and triacylglycerol (TAG) were investigated at 23 and 26 weeks of age in broiler breeder hens provided with ad libitum access to feed. Progesterone, oestrogen-β, thyroid-α and -β receptor mRNAs were also quantified in the infundibulum at the same ages.

2. A large variation in the ovarian morphology was observed at 23 weeks of age including hens with undeveloped ovaries, non-laying hens with post ovulatory follicles (POF) and a predominance of non-laying hens without a POF.

3. Serum concentrations of triglyceride, 17-β-estradiol and progesterone at 23 weeks of age were lower in hens with an undeveloped ovary compared with other groups of hens, whereas testosterone, triiodothyronine and thyroxin were higher.

4. At 26 weeks of age, the average number of hierarchical yellow follicles in normal layers was 7.64?±?0·41 whereas in internal layers, the follicular numbers were significantly greater at 8.66?±?0·53. The higher follicular numbers in internal layers were associated with higher serum triglyceride and progesterone concentrations.

5. Oestrogen receptor-β and thyroid receptor-β mRNA was up regulated in the infundibulum of internal layers compared with normal laying hens at 26 weeks of age.     

Dietary Supplements of Vitamins E and C and β-Carotene Reduce Oxidative Stress in Cats with Renal Insufficiency

Oxidative stress may contribute to the progression of chronic renal failure. In this study, cats with spontaneous renal insufficiency were fed a dry cat food supplemented with the antioxidants vitamins E and C, and β-carotene for 4 weeks. When compared with healthy cats, cats with renal insufficiency had a tendency to oxidative stress. The antioxidant supplements significantly reduced DNA damage in cats with renal insufficiency as evidenced by reduced serum 8-OHdG and comet assay parameters. Therefore, supplements of vitamins E and C and β-carotene as antioxidants may be beneficial to cats with renal disease. Partial data of this study were presented at the Experimental Biology meeting on 17–21 April, 2004. Washington DC, USA