2. When 20 ppm chlorine was used in the water supply to parts of the processing‐plant other than the mechanical immersion chilling system, counts of faecal and spoilage bacteria from carcasses were reduced approximately 10‐fold after passage through the chilling system; bacterial numbers were correspondingly decreased in the chiller water due to a carry‐over of chlorine from the final spray‐washer.
3. Artificial contamination of carcasses with a readily identifiable strain of Escherichia coli confirmed the occurrence of cross‐contamination during plucking and evisceration; in‐plant chlorination reduced neither the proportion of carcasses contaminated nor the numbers of organisms transferred at these stages.
4. In most cases the chlorine‐resistance of poultry spoilage pseudo‐monads was greater than that of E. coli; hence in‐plant chlorination is to be recommended for processing‐plant water supplies which carry such spoilage organisms. 相似文献
2. The proportions of ingredients eaten by the chickens given a free choice varied widely during the first 56 h of the trial. Thereafter, the proportions did not vary widely and birds given the free choice ate approximately ½ of their intake as whole wheat, ? of their intake as concentrate (high protein meals plus vitamin and mineral premixes), and 1/7 of their intake as whole sorghum each week for the three‐week trial period.
3. The nutrient composition of the free‐choice diet selected by the birds over the trial period averaged 12.09 MJ ME/kg feed, 210 g/kg crude protein, 14 g/kg calcium and 7 g/kg phosphorus.
4. At the end of the trial the average live body weights of the birds differed significantly according to method of feeding, in the descending order of pellets > mash > free choice.
5. The empty gizzard weight of birds differed significantly according to the method of feeding, in the descending order of free choice > mash > pellets.
6. The plucked empty bodies of birds given the free choice had a significantly lower concentration of crude protein than the plucked empty bodies of birds fed on mash or pellets. There were no significant differences between the treatments in the plucked empty body concentrations of fat, calcium or phosphorus.
7. Financial analysis indicated that free‐choice feeding was more profitable than feeding mash or pelleted diets to broiler chickens by 3.6% and 33.4% respectively. 相似文献
2. When the external temperature was below 10 °C the air temperature in the cage and pit area dropped below the favoured temperature of 20 °C. During winter, therefore, temperatures in some houses were often close to the lower limit for fly development.
3. Maximum temperatures of nearly 45 °C were recorded in some manure heaps, whilst others at the same point in the manure cycle were 10 °C lower. It was believed that the difference was due to the variation in the height of the manure pile, which in turn was determined by the cage stacking arrangements.
4. This difference could affect the rate of increase of predatory mites and beetles, so the design of the house may determine the type and extent of infestation. 相似文献
2. The problems could be overcome by water‐treatment of the barley or by addition of β‐glucanase.
3. The problems appear to be caused by a viscous factor, which is hydrolysed by β‐glucanase. Water‐treatment allows hydrolysis by enzymes in the barley.
4. Heat‐treatment of barley denatures hydrolytic enzymes and prevents reduction in viscosity. 相似文献
2. FFS were either unprocessed or extruded at 5 different temperatures (118°, 120°, 122°, 126° and 140°C) in a wet extruder. Diets were prepared with the different FFS, and a diet prepared with soyabean meal (SBM) was included as a control. The 7 experimental diets were fed to individual groups of 40 chickens each, for a period of 35 d. Trypsin inhibitor activity (TIA), urease activity (UA), and protein solubility in potassium hydroxide (PS) were measured in all FFS and in the SBM.
3. Diets prepared with raw FFS and FFS extruded at 118° and 120°G resulted in significandy lower body weights and in pancreatic hypertrophy; maximum growth rate was obtained with FFS extruded at 122° and 126°G, while minimum pancreas weight was seen in chickens fed FFS extruded at 140°C.
4. Although TIA, UA, and PS all decreased with increasing temperature of extrusion, TIA provided the best prediction of the feeding value of soyabeans for chickens. 相似文献
2. Storage of uneviscerated Wrolstad turkeys at 4 °C for 10 days caused no statistically significant changes in meat flavour or texture.
3. During further storage at —2 °C, however, there was a slight but significant change in flavour, which became more marked with time in birds which had been eviscerated after the initial period at 4 °C.
4. Both eviscerated and uneviscerated birds became slightly tougher during storage.
5. Initial holding at 4 °C increased the numbers of psychrotrophic bacteria on the skin by about 103 but subsequent changes at — 2 °C were slight for uneviscerated birds.
6. Eviscerated carcases had higher counts than uneviscerated birds after storage at — 2 °C and, although ‘off’ odours were not detected, spoilage appeared to be imminent at the end of the 20‐d period. 相似文献
2. Sixty‐four percent of time was spent lying. Individuals engaged in up to 41 separate lying bouts, which suggests that the birds were restless rather than resting.
3. Interrupted rest was sometimes caused by birds standing on each other; on other occasion it may have served to increase heat loss.
4. The frequency and duration of eating and drinking amongst individuals was variable. Neither dust‐bathing nor agonistic behaviour were observed and their absence may reflect the lack of importance of these behaviour patterns in meat chickens. 相似文献
2. Four different rearing treatments with a subsequent constant 16‐h photoperiod during laying were used.
3. A 15‐h rearing photoperiod resulted in delayed sexual maturity, increased mature body weight and decreases in both total egg numbers and the proportion of smaller eggs, compared with a 6‐h photoperiod.
4. Continuous light to 56 d, although associated with a high incidence of subsequent blindness, resulted in satisfactory egg production.
5. Abrupt reduction in the photoperiod from 15 to 6 h for the 112 to 167 d period resulted in unsatisfactory subsequent performance, especially when the day‐length was only slowly increased to 16 h during laying.
6. In the two laying treatments, in which the photoperiod was increased gradually from 6 to 16 h during the 168 to 238‐d period, a decrease in the number of smaller eggs occurred, compared with the treatments in which a single abrupt increase in photoperiod was used. 相似文献
2. Peripheral blood lymphocytes (PBL) were isolated from Cornell K‐strain Single Comb White Leghorn immature male chickens and cultured with various concentrations of Con‐A or PWM. Corticosterone, in different concentrations, was added to the cultures either 2 h before or 2 h after the addition of the respective mitogen.
3. Addition of corticosterone 2 h before the mitogens caused a significant suppression of lymphocyte proliferation in response to both Con‐A and PWM stimulation. Also addition of corticosterone 2 h after the mitogens caused significant suppression of proliferation in response to both mitogens; however, the degree of suppression was not as great.
4. The results indicate that after early activation events are initiated by the mitogens, lymphocytes are less sensitive to the effects of corticosterone. Because less suppression was seen in the cultures preincubated with PWM than those with Con‐A, it is likely that there are different sensitivities to corticosterone in the cell populations that respond to these mitogens. 相似文献
2. In this study, 108 different wheat lots were analysed for levels of extract viscosity as well as for endogenous endo-1,4-β-xylanase activity, and the impact of these two variables in animal performance was tested.
3. Results revealed that endogenous endo-1,4-β-xylanase activity and extract viscosity content varied widely among different wheat lots. Thus, a trial was conducted to evaluate the efficacy of exogenous enzyme supplementation in broiler diets using wheats with different levels of extract viscosity and endogenous endo-1,4-β-xylanase activity.
4. The data revealed that exogenous enzyme supplementation was only effective when the wheat present in the diet had high levels of extract viscosity (14.8 cP) with low endogenous endo-1,4-β-xylanase activity (347.0 U/kg). Nevertheless, it is apparent that exogenous microbial xylanases reduce digesta extract viscosity and feed conversion ratio independently of the endogenous properties presented by different wheat lots.
5. The data suggest that extract viscosity and/or endogenous endo-1,4-β-xylanase activity affect the response to enzyme supplementation by poultry fed on wheat-based diets. 相似文献
2. At each site, carcases, equipment or working surfaces were inoculated with a non‐pathogenic strain of nalidixic acid‐resistant Escherichia coli K12; transmission of the organism among carcases being processed was followed qualitatively and, where appropriate, quantitatively.
3. The degree of cross‐contamination and the extent to which it could be controlled by the proposed measures varied from one site to another. 相似文献
2. Ultracentrifuge experiments at 2.7 × 105 g gave values of s 20, W = (1.49 + 0.16C) × 10?13 s for the sedimentation coefficient and D20 w = (1.12 + 0.19c) × 10?6 cm2 s?1 for the diffusion coefficient, c being the protein concentration (g/100 ml).
3. According to the Svedberg equation, these imply a molecular weight of 12,470 daltons, assuming [v_bar] = 0.74 ml/g.
4. Using refractometer measurements of protein concentration it was found that E 1% 1cm (278 nm) = 5.57 at pH 7.8.
5. From the ultraviolet absorption spectrum of the protein in 0.1 N NaOH it was concluded that the molecule probably contains four tyrosine residues and no tryptophan.
6. On this basis a revised amino acid composition is given. 相似文献
2. The importance of the fowl in establishing the validity of Mendel's laws of inheritance is shown, together with the findings that made the bird the species of choice for much of the early work on animal genetics.
3. The early development of the egg production industry is outlined and the impetus given to this new commercial venture by the application of genetic principles, described. A review of the poultry meat sector is also given.
4. The role of the geneticist in increasing productivity in terms of numbers of eggs laid, meat produced and quantities of food required to produce both products is discussed and quantitative data presented.
5. The prospects for further improvements in productivity are assessed, particularly in the context of adverse environments both climatic and social. The prospective role of genetic engineering is also considered. 相似文献
2. In experiment 1, enzyme treatment of rye (1–0 g Tv cellulase/kg rye) improved weight gains by 15% (P<0–05) and food:gain ratios by 14% (P<0–05) but did not affect food consumption (P>0–05). Corresponding improvements produced by water‐soaking were 7 (P>0–05), 16 (P<0–05) and 10% (F<0–05). In the second experiment, similar trends occurred but improvements were less pronounced.
3. The second experiment also demonstrated that both enzyme supplementation and water‐soaking reduced the viscosity of both the diet and excreta, and increased the retention of fat.
4. Water‐soaking and fungal enzyme treatment caused an increase in extractable water‐soluble pentosans which were of sufficient molecular mass (not monomers or oligomers) to be almost entirely precipitated by 80% ethanol. Sufficient hydrolysis of these polysaccharides had occurred by both enzyme and soaking treatments, but not by normal digestion by chickens, to lower viscosity. The results suggest that the viscosity of rye can be reduced slowly by endogenous enzymes present in rye (water‐soaking), rapidly by a fungal enzyme preparation and in the lower sections of the gastrointestinal tract by microbial enzymes.
5. Both water‐soaking and enzyme treatment greatly improved the nutritive value of rye by bringing about a reduction in the viscosities of the water‐soluble and highly viscous pentosans. The results also suggest that the production of monomers or oligomers was not necessary for the lowering of viscosity observed with the two treatments. 相似文献
2. The air in two pits was found to be at a constant RH of 65%, suitable for drying, so accessory stirring fans were installed in one pit. The resulting changes in the moisture content of the manure were then compared with those occurring in the second pit with the unstirred air.
3. The minimum recorded moisture content of manure in the stirred pit was 240 g/kg, compared with 500 to 600 g/kg in the other. The air was, however, not distributed sufficiently evenly to achieve this moisture reduction throughout the pit. 相似文献
2. The pelleting degrees (PDs) were as follows: 0 mash; 0·5 mixture of soft pellets and mash 1 to 1; 1 soft pellets pelleted once; 1·5 mixture of soft and hard pellets 1 to 1; 2 hard pellets pelleted twice.
3. In experiment 2, the weight and length of the digestive organs were determined as well as digestive enzyme activities. In both experiments, the behaviour recorded was eating, standing, sitting and drinking.
4. Food intake and body weight gain were related to the degree of pelleting in a curvilinear manner. PD had a positive effect up to a peak (1 to 1·5 PD), after which its effect decreased. Food efficiency was not related to PD. In experiment 1, food efficiency of PDs 1 to 2 were superior to PDs 0 to 0·5 and in experiment 2, PDs 1·5 to 2 were superior to PD 0.
5. The relative weight of the gizzard was reduced by pelleting, whereas pelleting increased the relative weight of abdominal fat. The content of the crop was not affected by PD, whereas that of the proventriculus was lowest in the PD 2 group. Gizzard content was inversely related to PD. Pelleting reduced the length of the jejunum and ileum: which were shortened by about 15% with PDs 1 to 2, as compared to PD 0. The weight/length ratio of the jejunum and ileum tended to increase with increasing PD to a peak at PD 1·5, and to decrease thereafter.
6. Trypsin activity in the pancreas and amylase activity in the intestinal content were reduced by pelleting.
7. Chicks fed pelleted diets were less active: they ‘sat’ more and spent less time eating than their mash‐fed counterparts. 相似文献
2. The role of class IV MHC genes in resistance to Eimeria acervulina was assessed in F2 progeny of a cross between 2 meat‐type lines, selected divergently for immune response to Escherichia coli.
3. Disease susceptibility was assessed by lesion score, body weight, packed cell volume and carotene absorption.
4. Chickens with the “K” class IV MHC haplotype had lower lesion scores than chickens with “F” and “A” haplotypes.
5. Plasma carotene concentrations were higher in chickens with “K” haplotype and lower in chickens with “F” and “A” haplotypes whereas body weight and packed cell volume were less sensitive measures of Eimeria infection.
6. Eimeria acervulina resistance appears to be associated with MHC class IV genes; information about MHC haplotypes may be useful in selecting for increased resistance of meat‐type chickens to coccidiosis. 相似文献