Eggs from 31-wk-old ISA-White and ISA-Brown hens were sampled immediately after lay and after periods of storage of 1, 3, 5, and 10 d at room temperature. Longer periods of storage resulted in lower albumen weight and albumen height and higher albumen pH. Eggs from ISA-Brown hens had more albumen and shell than those from ISA-White hens, likely due to differences in selection history rather than due to pleiotropic effects of eggshell color. Within each line and storage period, the egg weight was more closely associated with albumen weight than with yolk or shell weight. The albumen height of eggs from ISA-Brown hens was lower than that of ISA-White hens at all storage times, but the albumen pH was not affected by the strain. Albumen height and albumen pH were statistically unrelated in fresh eggs, but the association became larger as the storage period increased, suggesting that albumen height measures factors that are present when the egg is laid and changes during storage, whereas albumen pH measures only the effect of storage.

Eggs from ISA-White and ISA-Brown hens between 28 and 59 wk of age were stored for up to 10 d to produce a sample of 5,763 eggs differing in the three major determinants of albumen quality. Eggs from ISA-Brown hens were larger and had less yolk, more albumen, and a greater percentage of shell than those from ISA-White hens. Egg size increased with increasing age of the hen, although more for the ISA-White hens than the ISA-Brown hens, and the yolk increased more in size than did the shell and albumen. During storage, albumen weight decreased and yolk weight increased slightly. The height of the inner thick albumen of eggs from ISA-White hens was greater than that of eggs from ISA-Brown hens, and it decreased as the hen age increased and with increasing time in storage. The pH of the albumen was not different between strains, and the effect of hen age was small, but it increased with time in storage. Regression coefficients of the height of the inner thick albumen on the weight of the egg were between -0.058 and 0.102, showing that the fixed regression of 0.05-mm albumen height per gram of egg implied by the Haugh unit is wrong. The statistical association between albumen pH and egg weight was very low. If albumen quality is being used as a measure of freshness, then the albumen height is biased by the strain and age of hen, whereas the albumen pH is not.

Production performance and egg quality were compared between 4 strains of beak-trimmed layers: 3 commercial strains-Lohmann White (LW), H&N White (HN), Lohmann Brown (LB)-and a noncommercial cross between Rhode Island Red (male) and Barred Plymouth Rock (female) in conventional cages and in floor pens. All chicks were reared and 857 pullets were housed at 18 wk of age in their respective environments. Body weight, hen-day egg production, feed consumption and efficiency, and egg quality were measured at wk 20, 30, 40, and 50. In floor pens, the location of eggs was recorded for 4 consecutive days at 4-wk intervals between 20 and 50 wk of age. Eggs from cages, nest-boxes, and the floor were tested for Escherichia coli and coliform contamination at 38 and 42 wk of age. Mortality was recorded during the rearing and laying periods. Housing systems significantly influenced BW and mortality but not feed consumption or feed efficiency. The interaction between environment and strain was significant for hen-day egg production at wk 20 to 30 and for BW at wk 30, 40, and 50. Hens in floor pens had greater BW, egg and yolk weights, and yolk color than those in cages. Commercial hens produced more eggs than the cross hens. Overall, HN hens had the best production performance, whereas cross hens had better egg quality. In floor pens, LW and HN hens laid most of their eggs in nest boxes, whereas LB and cross hens laid half of their eggs on the floor. Eggs from cages had lower E. coli and coliform contamination than those from nest-boxes and the floor, and E. coli contamination was greater for LB eggs than for LW eggs. Significant strain differences were found for the use of nest-boxes, with a high percentage of floor eggs for brown egg strains. This study suggests that genotype x environment interactions should be considered when alternative housing systems are proposed.

The effects of feed supplementation with the approved antimicrobial agents bambermycin, penicillin, salinomycin, and bacitracin or a combination of salinomycin plus bacitracin were evaluated for the incidence and distribution of antibiotic resistance in 197 commensal Escherichia coli isolates from broiler chickens over 35 days. All isolates showed some degree of multiple antibiotic resistance. Resistance to tetracycline (68.5%), amoxicillin (61.4%), ceftiofur (51.3%), spectinomycin (47.2%), and sulfonamides (42%) was most frequent. The levels of resistance to streptomycin, chloramphenicol, and gentamicin were 33.5, 35.5, and 25.3%, respectively. The overall resistance levels decreased from day 7 to day 35 (P < 0.001). Comparing treatments, the levels of resistance to ceftiofur, spectinomycin, and gentamicin (except for resistance to bacitracin treatment) were significantly higher in isolates from chickens receiving feed supplemented with salinomycin than from the other feeds (P < 0.001). Using a DNA microarray analysis capable of detecting commonly found antimicrobial resistance genes, we characterized 104 tetracycline-resistant E. coli isolates from 7-to 28-day-old chickens fed different growth promoters. Results showed a decrease in the incidence of isolates harboring tet(B), bla TEM , sulI, and aadA and class 1 integron from days 7 to 35 (P < 0.01). Of the 84 tetracycline-ceftiofur-resistant E. coli isolates, 76 (90.5%) were positive for bla CMY-2 . The proportions of isolates positive for sulI, aadA, and integron class 1 were significantly higher in salinomycin-treated chickens than in the control or other treatment groups (P < 0.05). These data demonstrate that multiantibiotic-resistant E. coli isolates can be found in broiler chickens regardless of the antimicrobial growth promoters used. However, the phenotype and the distribution of resistance determinants in E. coli can be modulated by feed supplementation with some of the antimicrobial agents used in broiler chicken production.

A total of 2123 eggs obtained from Brown Leghorn hens (unselected since 1965, ISA Brown, commercial brown egg layer) and Babcock hens (commercial white egg layer) at 32, 50, and 68 wk of age were used to investigate relationships among measures of albumen quality and a functional property of albumen. The eggs were sampled fresh and after storage for 5 and 10 d. At sampling, eggs were weighed and broken, and albumen height, pH, and volume after whipping for 80 s were measured. Also, yolks were weighed, dried shells were weighed, and albumen weight was determined by difference. Egg weight and the weights of the 3 principal components of the egg all increased with increasing age of the hen, with yolk weights increasing proportionately more. With storage, egg and albumen weights decreased, whereas yolk weight increased. Eggs from Brown Leghorn hens were smallest but had proportionately the largest yolks. Albumen height decreased with time in storage, and albumen pH and whipping volume increased. Differences between lines suggested that selection has changed the proportion of the yolk, albumen, and shell and has increased albumen height. Albumen height and whipping volume were negatively correlated, and differences between lines suggest that selection could have decreased the foaming ability of albumen, a principal reason for including eggs in many processed food products.

Scott, T. A., Silversides, F. G., Classen, H. L., Swift, M. L. and Bedford, M. R. 1998. Effect of cultivar and environment on the feeding value of Western Canadian wheat and barley samples with and without enzyme supplementation. Can J. Anim. Sci. 78: 649-656. The feeding value of nine wheat cultivars grown in replicate in three locations in each of two crop years, and 14 barley cultivars grown in seven locations over three crop years was tested with or without an appropriate commercial enzyme using a broiler chick bioassay. Four pens of six male broilers were fed mash diets containing 80% of the test cereal with or without enzyme from 4 to 17 d. Digestibilities were determined using an acid insoluble ash marker at 1.1% of diet. Significant intraclass correlation coefficients between duplicate wheat samples suggested a common effect of the location, but their low to moderate values suggested the presence of random variation or variation due to unique growing conditions within location. For both wheat and barley samples, the growing location affected the feeding value of the cereal grain and subsequent broiler chick performance. Durum wheat cultivars had higher feeding values than that of other wheat classes, both with and without enzyme supplementation, and the response to enzyme supplementation was low, likely reflecting a low level of soluble non-starch polysaccharides. The values of hulless barley cultivars were similar to those of hulled cultivars without enzyme, but the lower crude fibre in hulless barley resulted in higher feeding values when diets were supplemented with enzyme. The response to enzyme supplementation for both wheat and barley cultivars was dependent on the feeding value of the cereal grain without supplementation. Knowledge of variation in enzyme response could be used by feed manufacturers to determine the economic merit of supplementing with enzymes. Can J. Anim. Sci. 78: 649-656. La valeur alimentaire de neuf cultivars de blé cultivés en double à sept locals dans deux années et 14 cultivars d'orge cultivés à sept locals dans trois années à été verifiée avec ou sans enzyme commercial dans un essai biologique pour les jeunes poussins à chair. Quatre parquets de six poulets mâles ont été alimentés avec des rations moulées contenant 80 % de céréale à tester avec ou sans enzyme de 4 à 17 j. Les digestibilities ont été determinés en utilisant un marquer de cendre insoluble à l'acide à 1.1 % du ration. Des coefficients de corrélation intraclass entre les échantillons de blé en doubles ont suggeré un effet commun du local, mais leurs valeurs faibles ou moderées ont suggeré l'existance de variation soit aléatoire ou du aux conditions unique de culture a l'intérieur du local. Pour les échantillons de blé et d'orge, l'endoit a affecté la valeur alimentaire du céréale et la performance des poulets subséquente. Les cultivars de blé Durum avait des valeurs alimentaires plus elevées que d'autres classes de cultivar avec et sans enzyme et la réponse au supplémentation par enzyme à été faible, vraisembl...

Seed of the hemp cultivar Unika-b was cold-pressed to obtain hemp seed meal (HSM) containing 307 g/kg crude protein and 164 g/kg ether extract (60 g/kg linoleic acid, 120 g/kg alpha-linolenic acid, 160 g/kg oleic acid, lesser amounts of palmitic, stearic, and gamma-linolenic acids). For 4 weeks, 102 43-week-old DeKalb Sigma hens were fed on isonitrogenous and isoenergetic diets containing 0, 50, 100 or 200 g/kg HSM. Eggs were collected for fatty acid analysis during the fourth week of feeding these diets. No significant differences were found between feed treatments for egg production, feed consumption, feed efficiency, body weight change or egg quality. Increasing dietary inclusion of HSM produced eggs with lower concentrations of palmitic acid and higher concentrations of linoleic and alpha-linolenic acids.

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