Growth of subcutaneous chicken testicular transplants

Avian genetic resources have declined dramatically over the past half century, partly because the poultry community has been slow to adopt cryoconservation of avian germplasm. Techniques for gonadal cryopreservation and functional recovery have recently been developed but only some have been optimized. Chicks were castrated at 2 or 6 d and testicles were autotransplanted subcutaneously in one piece after disruption of the tunica membranes to optimize transplantation procedures without the complication of tissue rejection or immunosuppression. At 22 wk of age, the roosters were euthanized and growth of the testicular tissue was evaluated. Mortality with castration at 2 d was high but was much reduced with castration at 6 d. Transplantation of whole testicles subcutaneously on the back of chicks, without complete removal of the tunica membranes, yielded good growth of tissue with transplantation at 2 or 6 d of age. These results will contribute to the use of testicular cryopreservation and transplantation as an effective conservation strategy for avian germplasm. Further definition of the age of treatment will improve the overall efficiency.

Comparative costs of programmes to conserve chicken genetic variation based on maintaining living populations or storing cryopreserved material

1. There have been substantial losses of chicken lines kept for research in recent years and the objective of this research was to critically review alternative methods of preserving genetic resources. 2. The costs of programmes using living populations, semen cryopreservation and reconstitution, and ovary and semen cryopreservation and reconstitution were evaluated over 20 years using biological parameters of cryopreservation and population reconstitution that were derived from the literature. 3. Keeping live populations was most cost effective for periods of up to three years, but keeping live populations is increasingly difficult to justify with longer periods and any research population that will not be used within five years should be cryoconserved and in situ maintenance discontinued. 4. The rapid reconstitution possible using ovaries and semen would allow the inclusion of cryopreserved material in a short-term research project with the cost of recovery included in the budget. The low cost of cryoconservation suggests that all avian material should be conserved and reconstituted when needed for research.

Novel techniques for preserving genetic diversity in poultry germplasm

Abstract

There have been massive losses of avian genetic material over the past several decades, partly because of a belief that cryoconservation techniques used for mammals do not work for birds. For several avian species, cryopreservation of semen may not be sufficiently efficient to use in commercial practice but the fertility it produces is fully adequate for conservation purposes. Technology around embryonic primordial germ cells, which will produce the gametes, has been used to produce transgenic birds. These cells can be isolated, cryopreserved and recovered in chimaeras but the efficiency of recovery is far too low for conservation purposes because several dozen individuals must be produced to recover the variation from the original population. Cryopreservation of avian gonads with subsequent recovery of the germline through transplantation has been demonstrated recently and should provide the ability to both cryoconserve and recover avian populations.

Comparison of bones of 4 strains of laying hens kept in conventional cages and floor pens

The maintenance of bone strength has been an important issue in the debate over cage use for laying hens. Bone strength depends on adequate mechanical load and cages restrict movement. Four laying crosses (Lohmann White, Lohmann Brown, H&N White, and Rhode Island Red × Barred Plymouth Rock cross hens) were housed in conventional cages or in floor pens equipped with perches and nest boxes to measure the effect of the housing system on bone strength. Approximately 15 hens of each genotype from each housing system were killed at 50 wk of age and the radius and tibia of each were removed for analysis. There were no differences between the Lohmann White and H&N White (White Leghorn) hens, likely because of their similar genetic background. The Lohmann Brown and the cross hens (brown-egg layers) were larger and they had heavier bones, but the bone density was not different from that of the other lines. The radius was heavier for hens kept in floor pens than for those kept in cages, but the tibia was not. When hens were kept in floor pens, both bones had greater cortical bone density and cross-sectional area, but the difference between housing systems in cortical bone cross-sectional area was much greater for the radius than it was for the tibia. Although the movement of hens in cages is limited, they spend a great deal of time standing, which puts a mechanical load on the tibia. Hens in floor pens are able to stretch their wings or fly, in contrast to hens kept in cages, which likely explains why the difference between housing systems in cortical bone was greater for the radius than for the tibia.

Laying performance of six pure lines of chickens and four commercial hybrids at the Agassiz Research Centre

The Agassiz Research Centre keeps six pure lines of high-producing but non-commercial layers. Egg production, body weight, feed consumption and efficiency, and several characteristics of the eggs were measured to 60 wk of age and compared with those of four commercial white- and brown-egg hybrids. Egg production from 20 to 60 wk was highest for the four commercial hybrids, with no difference between them, and was 6 to 11% lower for the pure line white-egg layers, and 7 to 13% lower for the pure line brown-egg layers. The pure line and hybrid white-egg layers had similar body weights, but the pure line brown-egg layers weighed more than the commercial brown-egg hybrid. Feed efficiency was similar for the four hybrids and was generally better for the hybrids than the pure lines, based largely on higher egg production rather than increased feed consumption. The difference between industrial hybrids and the pure lines studied can be attributed to the selection that has been applied as well as to heterosis. Key words: Chicken, genetic resources, Agassiz layer lines

Invasive and noninvasive measurement of stress in laying hens kept in conventional cages and in floor pens

Measurements of the heterophil:lymphocyte (H/L) ratio (invasive technique) and corticosterone in yolk and albumen (noninvasive techniques) were used to measure stress in 3 commercial laying strains, Lohmann White (LW), H&N White (HN), Lohmann Brown (LB), and a noncommercial cross (CR) between Rhode Island Red (male) and Barred Plymouth Rock (female), kept in conventional cages or floor pens. All chicks were reared in their respective environments, and 450 and 432 pullets were placed at 18 and 7 wk of age in cages and floor pens, respectively. Blood from 12 hens per strain was taken at 19, 35, and 45 wk of age in each housing system. A total of 100 heterophils and lymphocytes were counted and their ratio (H/L ratio) was calculated. Corticosterone was measured in yolk and albumen from 12 hens per strain in each housing system at 22 and 45 wk of age. The H/L ratio was within the normal range. The interaction between environment and strain for the H/L ratio showed that in both environments, LB and CR hens had a higher H/L ratio than LW and HN layers. In cages, there were significant differences in H/L ratios between LW and HN hens that were likely due to genetic differences. The LW hens had significantly lower corticosterone concentrations in yolk than LB hens. In cages but not floor pens, yolk corticosterone concentrations at wk 22 were significantly higher than at wk 45. In floor pens but not cages, albumen corticosterone at wk 22 was higher than at wk 45. The H/L ratios suggest that none of the hens were unduly stressed, and corticosterone levels in yolk and albumen support the suggestion that hens adapted to their environments with age. Although measurement of yolk corticosterone and the H/L ratio may be comparable, the measurement of corticosterone level in the albumen may differ because it is secreted over a short time.

Cryopreservation of germplasm from chickens kept in Canadian research institutions

Twenty-three genetically distinct lines of chickens are maintained as living populations by Agriculture and Agri-Food Canada and Canada’s eight Faculties of Agriculture. Historically, cryogenic storage of avian genetic material has been difficult, but we have developed techniques of gonadal transplantation to allow recuperation of stored genetic material into living birds. Gonads from 1660 day-old chicks or late-term embryos (810 females and 850 males) from 18 chicken populations from four Canadian institutions were harvested and cryopreserved using dimethylsulfoxide as a cryoprotectant. Future efforts will be directed to completing the collection of the populations kept in Canadian publicly-funded institutions that conduct agricultural research. Key words: Chicken, genetic resources, cryopreservation, gonads

Effect of wheat type grinding, heat treatment and phytase supplementation on growth efficiency and nutrient utilization of wheat-based diets for broilers

This experiment studied the effect of phytase and processing (heat treatment, grind size) on performance and nutrient utilization of broilers fed diets from 1 to 21 d that included hardred spring (HRS) and durum wheat with three grind sizes (470, 560, 630 µm) with or without heat treatment (oven dry at 80°C for 15 h) before supplementation with phytase (Natuphos® 0 or 600 FTU kg-1). All 24 diets contained 0.5 g Avizyme 1302 kg-1 and were formulated (80% wheat, 20% basal diet) to supply nutrients necessary to meet the requirements of broiler chicks, except for a low level of nonphytate phosphorus (P, 2.7 g kg-1). The medium ground HRS-based diet produced significantly better feed conversion ratio (FCR) and body weights compared with the other two grind sizes. Heat treatment significantly improved feed conversion ratio and apparent metabolizable energy (AME), protein, and P digestibility of diets. It also significantly decreased feed intake, but produced no differences in 21 d body weight. Supplementation with phytase significantly improved AME, protein, and P digestibility of test diets. The AME of diets was influenced by wheat type, processing and grind size. Phytase increased N and P digestibility. Improvements in N and P digestibility by phytase and heat treatment were dependent on wheat type and grind size.The present results suggest an advantage of both phytase and xylanase in durum- and HRS-based diets. Heat processing destroyed endogenous phytase and xylanase in wheat-based diets, and increased the levels of soluble non-starch polysaccharides. Combined phytase, heat treatment, and grind size may synergistically improve N and P digestibility. Key words: Wheat source, grind size, heat treatment, phytase, digestibility, broiler

Production of offspring from cryopreserved chicken testicular tissue

Cryopreservation of avian germplasm provides a means of genetic banking for future needs in biological research and animal production. The sperm of birds can be cryopreserved and used to fertilize eggs. However, the fertility of frozen-thawed avian semen is generally much lower than that of mammalian semen and varies among species or among lines, reducing the value of semen for the preservation of genetic resources. In the present study, a simple freezing protocol was used to cryopreserve testicular tissue of day-old chicks, and after subsequent transplantation, the frozen-thawed testicular tissue developed functional seminiferous tubules that produced sufficient sperm to fertilize eggs, resulting in donor-derived offspring. This study provides an alternative to semen cryopreservation for storage of the male germline in birds.

Offspring Produced from Orthotopic Transplantation of Chicken Ovaries

The loss of avian genetic variation and the threat of disease lend urgency to the cryopreservation of remaining poultry stocks. However, techniques for freezing ova and embryos are not available for birds, and the recovery of genetic material has been a major obstacle to cryopreservation. To overcome this problem, we transplanted chicken ovarian tissue just after hatch with or without subsequent treatment of the recipient with an immunosuppressant. Nine of 12 hens in the nonimmunosuppressed group and 6 of 9 birds in the immunosuppressed group produced eggs, whereas 3 hens in each group produced donor-derived offspring. These results suggest that transplantation of ovarian tissue of chickens is possible if performed just after hatch. This finding should allow efficient cryopreservation of female germ cells in chickens with regeneration in live birds. In addition, ovarian transplantation could be useful for studies in genetics or developmental biology or could provide convenient access to the female germline for genetic manipulation.

Effect of strain of layer and age at photostimulation on egg production, egg quality, and bone strength

Bone strength in layers is a concern for economic reasons and animal welfare concerns. Bone characteristics were investigated in 3 strains of hens: Babcock B-300, a small-bodied commercial white-egg layer; ISA-Brown, a commercial brown-egg layer; and an unselected Brown Leghorn line (BL). After being reared together in a single pen with 8 h of light per day, hens were caged with 14 h of light per day. Half of the hens were caged at 18 wk of age and the other half at 20 wk of age, resulting in a 2-wk difference in the age at photostimulation. Body weights, egg production, feed efficiency, and egg quality were measured throughout production. At 15, 25, 50, and 74 wk of age, hens were euthanized for sampling of the radius and the humerus. Breaking strength of the radius and humerus was measured, and the area and density of trabecular (largely medullary bone) and cortical bone were measured using quantitative computed tomography. Egg production and feed conversion of ISA-Brown hens was as good as or better than that of Babcock B-300 hens, and both commercial strains had higher production than the BL. Photostimulation late delayed sexual maturity and improved albumen and shell characteristics but had only minor effects on egg production and did not affect the yolk weight. The delayed photostimulation resulting from caging 2 wk later affected the radius by increasing the area of the trabecular space at 50 wk of age and the density of the bone in the trabecular space at 74 wk of age. Breaking strength of the humerus at 25 wk of age was greater for the birds that were photostimulated late but was not different later in the trial. The humerus, but not the radius, of the BL had a greater breaking strength than that of the commercial strains, suggesting that selection has decreased humeral breaking strength.

A comparison of grinding processes and wet feeding of wheat-based diets on AME, production, and gastrointestinal tract development of broiler chicks

This experiment studied the effect of grind mill type [hammer (HM) or attrition (AM)], grind size (5.6 mm 4.8 mm, and 2.4 mm) and wheat type [Durum or Hard Red Spring (HRS)] on the performance, energy retention (AME), and the gut development of broilers fed these diets with or without 1.2 g water-1 g dry feed added. Twenty-four dietary treatments (2 grind types × 3 grind sizes × 2 wheat types × wet or dry feeding) were each fed to four cages of six male broilers from 1 to 17 d of age. Wet diets were prepared daily. Feeding diets with water increased 17 d body weight and feed intake of broilers compared with feeding the diets dry. Body weight and feed intake of broilers fed the HM diets were greater than those of broilers fed diets containing wheat processed by AM. Feed intake and FCR with HRS-based diets were higher than those for Durum-based diets. The AME for Durum was higher than for HRS and the ME efficiency (kcal g-1 BW) was greater, indicating a lower efficiency. The AME intake of HM ground wheat was higher than for that for wheat ground with the AM. The type of grinding, the wheat type, and the addition of water all affected the length and weight of the digestive system, likely through their effects on the rate of water absorption and passage through the gut. Particle size did not affect any measurement. Hammer milling produced a uniform particle size and less fines and may be better suited for processing wheat in broiler diets. Key words: Broiler, wheat, wet feeding, AME, gut development

The Technique of Orthotopic Ovarian Transplantation in the Chicken

A surgical technique has been established for orthotopic transplantation of ovarian tissue in newly hatched chickens. In these trials survivability of the chicks after surgical manipulation was 100%. The size and orientation of the ovary at 2 wk of age suggested that the graft was attached and had undergone development. This technique should allow the development of a cryopreservation protocol of chicken ovarian tissue for the conservation of poultry genetic material.

A Study on the Interaction of Xylanase and Phytase Enzymes in Wheat-Based Diets Fed to Commercial White and Brown Egg Laying Hens

A trial was conducted to investigate potential interactions between phytase and xylanase enzymes in wheat-based laying diets. Hens (480 ISA-White and 480 ISA-Brown) were distributed into 160 experimental units and fed one of 10 diets containing 75 to 77% wheat from 33 to 64 wk of age with a diet change at 49 wk. Two diets were adequate in P content (0.3 and 0.25% available P in the 2 phases) with or without xylanase (0 or 2,000 U/kg; Avizyme 2300, Danisco Animal Nutrition, Marlborough, Wiltshire, United Kingdom), and 8 diets had reduced P (0.2 and 0.15% available P) with or without xylanase and phytase (0, 300, 500, and 700 ppu/kg; Phyzyme 5000G, Danisco Animal Nutrition). Egg production was higher for ISA-Brown than for ISA-White hens, and ISA-Brown hens were larger. Eggs from ISA-Brown hens had lower albumen height; higher egg, shell, and albumen weights; and lower yolk weight than those from ISA-White hens. Egg production was not affected by the diet. In P-reduced diets without xylanase, phytase significantly increased BW gain in the first period with no change in feed intake or feed efficiency. In P-adequate diets, xylanase increased egg and albumen weight and albumen height. In P-reduced diets with xylanase, increasing levels of phytase increased egg and albumen weight. This trial demonstrated no negative interactions between these enzymes for production traits and no interactions between the diet and strain of hen. These data suggest that poultry producers can use these enzymes individually or together in feed for the Brown and White egg layers used in this study without concern for the strain of hen.

Effect of cultivar and enzyme supplementation on nutrient availability and performance of broilers fed Maritime Canadian wheat

The feeding value of wheat is affected by the content of soluble non-starch polysaccharides (NSP), which varies among cultivars and the environment in which they are grown. Dietary enzymes can reduce the negative effects of NSP and improve the apparent metabolizable energy (AME) content of the wheat. This study examined differences in feeding value of four wheat cultivars grown in 2 crop years in the Maritime provinces of Canada and the need for enzymes. In a growth trial, diets containing one of the Maritime wheats or corn were fed with or without commercial enzymes containing, for wheat-based diets a mixture of xylanase and protease, and for corn-based diets a mixture of xylanase, protease, and amylase. In a broiler chick bioassay, diets containing 80% wheat were fed with or without a commercial enzyme with xylanase and protease activities. Enzymes significantly lowered body weight gain of birds fed Walton wheat in the second year, and improved the grower feed conversion ratio of birds fed Norboro wheat. Enzyme supplementation significantly improved apparent metabolizable energy and digestibility of crude protein. The AME content did not appear to be a direct indicator of performance. There were significant differences in AME content among the wheat samples. Enzymes generally did not improve performance in this study, possibly due to the relatively low in vitro viscosity values of these samples. Maritime wheats were equal or compared favourably with the sample of wheat from Western Canada and to locally obtained corn. Key words: Wheat, broiler performance, apparent metabolizable energy, enzyme

The effect of feeding hemp seed meal to laying hens

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.

Bone breakage in three strains of end-of-lay hens

Spent hens of two commercial lines and one heritage line of layers were slaughtered at 72 wk of age and dissected to determine the number of bone fractures before shipping, during depopulation and shipping, and during slaughter. The ISA-Brown and Babcock B300 hens had higher incidences of old (11.1 and 11.7%) and shipping breaks (7.9 and 10.0%) than a line of Brown Leghorns (0.0 and 3.5%, respectively), suggesting that selection of commercial layers for increased egg production may have affected bone strength. All hens experienced broken bones during processing. Key words: Layers, strain, bone breakage

The Relationships Among Measures of Egg Albumen Height, pH, and Whipping Volume

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.

Effect of wheat cultivar and enzyme supplementation on nutrient availability and performance of laying hens

This study examined the effect of four wheat cultivars (Belvedere, Glenlea, Norboro, and Walton) grown in the Maritime provinces of Canada and dietary enzyme supplementation on apparent metabolizable energy (AME), digestibility of crude protein (CP), and performance of laying hens, and compared these values to those obtained using a corn-based diet. Forty groups of three adjacent battery cages, each housing two hens, were fed each diet which included the wheat samples (61.0%) or locally obtained corn (65.1%), with or without commercial enzymes containing a mixture of xylanase, protease, and amylase for corn-based diets and a mixture of xylanase and protease for wheat-based diets. Excreta samples were collected at 17 d for analysis of nutrient retention. The diet that the hens consumed had no significant effect on performance. The feed conversion ratio of hens was lowest (1.79) in the final week of the experiment when egg production was highest (97.0%) and feed intake lowest (109 g bird-1 d-1). The diet significantly affected both AME and digestibility of CP. The wheat cultivar influenced the AME and digestibility of CP when these diets were fed to laying hens, with enzyme supplementation reducing the AME and digestibility of CP for diets containing three (Belvedere, Glenlea, and Walton) of the four wheat cultivars. The significant improvement with enzyme supplementation of the corn-based diet is promising and should be the basis of future studies. Key words: Wheat, layers, apparent metabolizable energy, enzyme

The effect of phytase enzyme and level on nutrient extraction by broilers

Three experimental phytase enzyme preparations derived from the same Escherichia coli gene but produced in Saccharomyces cerevisiae (A), Pichia pastoris (B), and Pseudomonas fluorescens (C) were compared with a commercial enzyme preparation by addition to wheat-soybean meal diets fed to broiler chicks. A positive control diet contained sufficient available phosphorus for normal broiler growth and a negative control diet was phosphorus deficient. The 4 enzymes were added to the negative control diet at 3 levels each (150, 450, and 1,250 U/kg), and all diets were pelleted above 80 degrees C. Broiler chicks were fed experimental diets from 4 to 21 d. Chick performance and nutrient digestibility showed that the pel leting process inactivated enzymes A and C and the commercial enzyme. When added to the negative control diet, enzyme B had positive effects on broiler performance and calcium and phosphorus digestibility, and increasing levels of enzyme had greater positive effects. Enzyme B also increased the AME and protein digestibility over those of either control diet. These results suggest that enzyme B was not inactivated by pelleting above 80 degrees C, whereas the other enzymes were.

Effect of pelleting and enzyme supplementation on variation in feed value of wheat-based diets fed to broiler chicks

The effect of wheat cultivar, pelleting, and enzyme supplementation was measured with a broiler chick bioassay comparing differences in feed intake, growth, FCR and metabolisable e nergy (ME) level. Samples of two wheat cultivars from each of six classes were ground and were either unpelleted or pelleted and ground before including (80%) in mash diets with or without enzyme (Avizyme 1302). Two common control diets were fed in the two bioassay series required to evaluate the 48 diets. Each diet was fed to four cages of six male broilers from 4 to 17 d of age. Apparent metabolisable energy (AME) was determined on excreta collected at 16 d of age. There was more than a 25% difference in feed intake among the 48 diets; the largest contribution of the variation was due to wheat cultivar. Feed intake was significantly increased by enzyme addition and decreased by pelleting. Variation in feed intake explained more than 70% of the variation in body weight and had only a minor association with determined AME. The AME of all wheat samples, except the two Durum wheats, was increased by both enzyme supplementation and processing. The increase in AME with processing may represent an anomaly of using different bioassay series to measure unpelleted and pelleted wheat samples or it may represent changes in AME of all wheat samples, except Durum wheats, with storage after harvesting. The relative AME and FCR measurements for the 12 wheat samples were similar whether the wheats were pelleted or not. However, there was no relationship between measurements of feed intake when the different cultivars of unpelleted and pelleted wheat were compared. The marked variation in feed intake and growth rate of broilers fed different cultivars of wheat continues to be a concern as it suggests that other factors may limit intake and prevent the broiler from obtaining the required levels of nutrients from the diet. Key words: Wheat, feed processing, enzymes, feed value, broilers

Defining the effects of wheat type, water inclusion level, and wet-diet restriction on variability in performance of broilers fed wheat-based diets with added water

The objectives of the study were to determine if feed conversion ratio (FCR) in broilers fed wet Hard Red Spring (HRS) as compared to Durum-based wheat diets could be reduced by: (a) diluting HRS with Durum wheat, (b) pelleting of the wheat, (c) adding different levels of water to the diet, or (d) restricting intake of diets to which water was added. Three wheat types [Durum, HRS and a Composite (50:50) sample] were ground, with one portion of the ground grain being pelleted and reground before both forms of each wheat type were included at 80% of a basal broiler diet. All diets were supplemented with a commercial wheat enzyme and fed as a mash. Each of the six diets was fed in one of four feed regimens: DRY (as is); WET1.2 (DRY with 1.2 g water g-1 feed); WET0.6 (DRY with 0.6 g water g-1 feed); and RWET1.2 [WET1.2 diet treatment restricted-fed to 120% of the previous day’s DRY feed intake (on an air-dried basis) for each diet type]. This provided 24 dietary treatments each fed to six cages of five male broilers from 1 to 21 d of age. The wet diets were prepared daily. Among the feed regimens WET1.2 resulted in the significantly highest 21-d body weight. The significant increase in feed intake and FCR of HRS-based diets with added water was reduced significantly by diluting this wheat with Durum wheat. Feeding the unpelleted Composite wheat sample significantly improved growth rate over either wheat alone, presumably due to an improved balance of nutrients. Pelleting significantly reduced intake of wet HRS-based diets and increased apparent metabolisable energy (AME), resulting in a marked reduction in FCR compared to unpelleted diets. There was some value in using less water in HRS-based, but not in Durum-based diets, with respect to FCR and metabolisable energy retention. Physical restrictions of feed intake reduced FCR of wet (WET1.2) unpelleted HRS diets, but did not affect the same diet when wheat was pelleted. Further work is required to establish the optimum consistency of feed in a wet form to maximize feed intake and growth while minimizing FCR. Key words: Wheat, wet feeding, enzymes, feed intake, broilers

The effect of adding exogenous phytase to nutrient-reduced corn- and wheat-based diets on performance and egg quality of two strains of laying hens

A laying trial was conducted in which ISA-Brown and ISA-White hens were fed diets based on corn or wheat that had been pelleted to eliminate endogenous phytase. Control diets were formulated to contain adequate levels of all nutrients. Nutrient-reduced diets were formulated to account for nutrients released by the phytase. To formulate these diets, phytase was entered into the matrix with a value, on a weight basis, of 1,173% for CP (60.5% for lys, 29.4% for met plus cys, 40.0% for thr), 39 900 kcal kg–1 for AME, 666% for Ca, and 333% for available P. A negative control diet was based on the modified formulation but did not include phytase. Differences between diets were observed for tibia ash, and Ca and P in the ash, as well as for BW and measures of egg quality. Egg production likely provided the best measure of the adequacy of P nutrition. In the final period of production, feed intake and egg production of hens fed the nutrient-reduced corn-based diet without enzyme was lower (P < 0.05) than that of hens on the control diet. Egg production of hens fed the nutrient-reduced diet with phytase was similar to that of hens fed the control diet, showing that inclusion of phytase permits formulation of corn-based diets with reduced levels of energy, CP, Ca, and P. No major effect of diet was seen for the hens fed wheat-based diets indicating that the formulation changes used may not have been appropriate for evaluating a response to exogenous phytase in wheat-based diets. Key words: Phytase, layers, corn, wheat, phosphorus

Effect of storage and layer age on quality of eggs from two lines of hens

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.

The effect of storage and strain of hen on egg quality

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.

The effect of phosphorus, phytase enzyme, and calcium on the performance of layers fed wheat-based diets

A trial was performed to test the effects of two levels of Ca (3.7 and 4.0%), two levels of available P (0.2 and 0.4% until 55 wk, 0.11 and 0.22% from 55 to 67 wk), and three levels of phytase enzyme (0, 250 and 500 FTU kg−1) on the performance of laying hens fed diets based on wheat and soybean meal. Phytase supplementation had only small effects, likely because the endogenous phytase in the wheat liberated sufficient phytate-bound P to compensate for only marginally deficient levels. In contrast to what has been found with corn-based rations, there were no negative effects of high levels of AP or of enzyme, suggesting that the effect of exogenous phytase was more complex than a simple liberation of phytate P. Endogenous phytase should be considered when formulating rations based on wheat. Key words: Phytase, layers, wheat, phosphorus, calcium

The effect of phosphorus, phytase enzyme, and calcium on the performance of layers fed corn-based diets

An experiment employing a factorial arrangement of two levels of Ca, two levels of available P (AP), and three levels of phytase enzyme was carried out with 360 ISA White layers from 18 to 67 wk of age. The Ca levels were maintained at 3.7 and 4.0% throughout the experiment. The AP levels were 0.2 and 0.4% for the high and low treatments until 55 wk of age and were reduced to 0.11 and 0.22% thereafter. Phytase enzyme levels were 0, 250, and 500 phytase units (FTU)/kg of feed. In the period before Week 55, either level of AP was likely adequate for maximum production. However, when lower levels of AP were fed after this time, low AP was associated with reduced BW and egg production, and enzyme supplementation was able to compensate for low AP. In this period, high AP and the highest level of phytase produced negative effects on BW, egg weight, and the feed conversion ratio. The ratio of Ca to AP was important; shell quality was best with high or low levels of both. With high levels of Ca, enzyme supplementation compensated for low levels of AP and overcompensated with a high level of AP. These effects were reduced or absent with low levels of Ca. It is clear from this study that phytase enzyme can compensate for low levels of AP in diets based on corn and soybean meal, but that the optimum level of supplementation depends as well on the Ca level.

Ovarian follicular growth and maturity and follicular production of progesterone and oestradiol in response to porcine luteinising hormone and porcine follicle stimulating hormone in albino (S*AS) hens in vivo and in vitro

The effects of the SAS gene on follicular growth were studied by feeding Sudan IV and Sudan Black B, on follicular maturity by measuring P4 and E2 output of the 5 largest follicles (F1 to F5) in vitro, and on ovarian response (plasma progesterone, P4, and oestradiol, E2) to administration of porcine follicle-stimulating hormone (pFSH) and porcine luteinising hormone (pLH) in old laying hens. Albino hens had fewer dye rings in the yolks of their eggs than non-albinos (8.32 compared to 8.59) and the yolks from albinos weighed less. The numbers of normal and atretic follicles larger than 3 mm in diameter did not differ between the two genotypes. The P4 outputs from the F1 and F2 follicles were significantly greater for albino hens, but P4 production of other follicles was not different for the two genotypes. The P4 output of the F1 follicle in response to pLH was dose-dependent and greater for albino hens than for non-albinos. Porcine LH did not increase the follicular E2 output in either genotype. Administration of pLH, but not pFSH, increased plasma P4 and E2 concentrations, with no difference between genotypes. These data suggest that the F1 follicles for albino hens are precocious, resulting in a reduced growth period and a smaller weight at ovulation.

Effect of pelleting temperature on the recovery and efficacy of a xylanase enzyme in wheat-based diets

Two trials were performed to test the stability and efficacy of a commercial enzyme preparation containing xylanase and protease activities to pelleting. In Trial 1, 576 male Cobb chicks were fed wheat-based diets to 21 d with or without enzyme and pelleted after conditioning for 55 or 140 s at 70, 75, 80, 85, 90, or 95 C. In Trial 2, 2,880 male Cobb chicks were fed wheat-based diets to 42 d with no enzyme, or with enzyme addition before or after pelleting with conditioning for 30 s at 70, 80, 90, or 95 C. Enzyme addition had a positive effect on BW gain and the feed to gain ratio (FG) in Trial 1 and on FG to 42 d in Trial 2. All treatment effects were significant for intestinal viscosity in both trials. Two- (BW) and three-way (BW, FG) interactions between enzyme, temperature, and time were seen in Trial 1. With enzyme supplementation, second degree polynomial equations of performance on conditioning temperature had high R2 values for BW and FG, with temperatures between 80 and 85 C being most favorable. Enzyme activity in unsupplemented diets measured in vitro was largely eliminated at temperatures above 80 C, whereas the decline in activity in supplemented diets was linear. In spite of the decline in enzyme activity measured in vitro, intestinal viscosity of chicks fed enzyme-supplemented diets remained low with high processing temperatures, whereas that of chicks fed unsupplemented diets increased dramatically.

Effect of feed form, formulation, and restriction on the performance of laying hens

A laying trial was performed with 1440 DeKalb® hens caged at 18 wk of age to test the effect of feed form (expanded pellets or mash) and type of formulation (for crude protein [CP] or for specific amino acids[AA]), and five levels of feed restriction applied at either 24 wk or 32 wk of age. Formulation for CP rather than AA content resulted in 4.4% greater egg production and 7.1% greater production of egg mass in hens fed mash and 4.0% better feed efficiency in hens fed both mash and pellets. Hens fed mash had 2.3% higher feed consumption, suggesting that the hens may prefer mash. Feed restriction reduced body weight and hen–day egg production proportionate to the restriction level, but egg weight was reduced only slightly. These data suggest that care should be exercised in formulating for AA content rather than for CP, especially if feed intake is reduced. This strain of hens was very successful at regulating its feed intake for maximum production, and even a slight feed restriction produced a negative effect on production. Key words: Laying hens, feed restriction, feed form, feed formulation, protein level

Effect of enzyme supplementation of broiler diets based on corn and soybeans

Digestibility of diets based on corn and soybean meal or soybeans treated by roasting or extrusion, with or without an enzyme supplementation, was measured by "true" (Sibbald) methods, by analysis of excreta, and by analysis of ileal digesta. Only analysis of ileal digesta was able to consistently measure differences between soybean and enzyme treatments in the digestibility of CP, starch, fat, and ME. The amino acid (AA) digestibility of the diets was measured by analysis of the ileal contents. Whereas enzyme supplementation improved overall CP digestibility by 2.9%, this improvement was not equal for all AA. Of the AA most important for broilers fed corn-soybean diets, the digestibilities of Lys, Met, and Arg were not improved or not improved significantly by the enzyme supplementation; however, that of Val was improved by 2.3% and that of Thr was improved by 3.0%. A performance trial demonstrated that enzyme supplementation with equal diet formulation improved BW and the feed conversion ratio by 1.9 and 2.2%, respectively. A second performance trial compared standard diet formulations with formulations using enzyme supplementation and energy levels that were reduced by the amount of improvement provided by the inclusion of enzyme in the first performance trial. No difference was seen between treatments, showing that the improvement of nutrient utilization brought about by enzyme supplementation completely compensated for the reduced energy content. Whereas enzyme supplementation should allow a reduction in CP formulation as well, individual AA were not improved equally by supplementation and should also be balanced.

Prediction of the performance of broiler chicks from apparent metabolizable energy and protein digestibility values obtained using a broiler chick bioassay

Samples of wheat (54) and barley (87) were included in a series of broiler chick bioassays. For each cereal, fed at 80% of a basal diet with or without enzyme, apparent metabolizable energy (AME), retained nitrogen, digesta viscosity, excreta dry matter (DM), and broiler performance (feed intake, body weight [BW] gain, and feed conversion) were measured. Correlation coefficients were calculated between the predictor and the performance variables, separated according to whether or not the diets included feed enzymes. Some correlations between measures of AME and BW, feed efficiency, and to a lesser degree feed intake were significant, but none were high. The correlation coefficients were higher when feeds were not supplemented with an enzyme because enzyme supplementation reduced the variation in both AME and performance by reducing the antinutritive effects of non-starch polysaccharides (NSP). Including a measure of voluntary intake in AME (AME level multiplied by feed intake) resulted in higher correlations with performance. Evaluation of the feeding value of wheat and barley by researchers or the feed industry will require the determination of available energy and the NSP contents. Key words: Metabolizable energy, performance, wheat, barley, feed enzymes

Effect of cultivar and environment on the feeding value of Western Canadian wheat and barley samples with and without enzyme supplementation

The feeding value ofnine 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. Key words: Metabolizable energy, broilers, performance, wheat, barley, enzyme

The effect of wheat cultivar, growing environment, and enzyme supplementation on digestibility of amino acids by broilers

Fifty-four samples of wheat, representing duplicate samples of nine varieties grown in three environments, were included in chick bioassays using rapidly growing broilers, complete diets, and enzyme supplementation to remove the deleterious effects of non-starch polysaccharides. An insoluble ash marker was included in the diets, which allowed calculation of apparent digestibilities of CP and AA in the grain from analysis of the ileal contents obtained after sacrifice of the chicks at 17 d of age. The wheat cultivars contained from 13.5 to 16.8% CP and differed in the percentage of specific AA, with Pro, Glu and Phe making up proportionately larger parts of high CP samples than low CP samples. Without enzyme supplementation, the digestibility of CP varied from 83 to 88% and that of specific AA from 76 to 94%, determined in part by the class and variety of wheat. Xylanase enzyme supplementation improved the digestibility of protein by an average of 4%, and reduced the differences in digestibility between wheat samples. These results suggest that variation between wheat samples should be taken into consideration when formulating broiler feed, especially when formulation is for specific AA. Enzyme supplementation may provide a partial alternative to using high-quality protein sources or supplementing with synthetic AA. Key words: Broiler chicken, digestible amino acids, digestible protein, wheat, enzyme

A broiler chick bioassay for measuring the feeding value of wheat and barley in complete diets

Energy is an important component of poultry feed and is derived principally from cereal grains. Unfortunately, all of the chemical energy is not available to the bird, and biological assays must be used to determine the digestible energy value of a cereal grain. The bioassay described uses four pens of six male broiler chicks, complete diets containing 80% of a test cereal grain (with or without an appropriate commercial enzyme), and ad libitum feed intake. Apparent metabolizable energy values (kilocalories per kilogram of cereal grain, DM basis) values are calculated from gross energy and acid insoluble ash measurements of diet and excreta collected for 24 h at 16 d of age. To monitor variation between broiler chick assays, due to bird, environment, etc., common control samples of Hard Red Spring (HRS) and Canadian Prairie Spring (CPS) wheat were tested in each of 15 separate assays over 2 yr. Similarly, for barley, control samples of hulled and hulless barley were repeatedly tested in five assays. Broiler performance in this study was lower than expected for commercial broilers, in part due to a high dietary cereal grain component and the fine mash texture. However, AME values as determined were comparable to those reported in the literature for wheat and barley. The CV for AME measured among pens, representing the intra-assay CV, was between 1.2 and 3.4% and was lower with enzyme supplementation. The interassay CV was only slightly higher than the intra-assay CV. This assay provides precise estimations of ME in cereal grains fed to young broilers that can be used for diet formulation or for verification of laboratory measures of feeding value of cereal grains.

Comparison of sample source (excreta or ileal digesta) and age of broiler chick on measurement of apparent digestible energy of wheat and barley

The broiler chick bioassay measures AME of wheat- or barley-based diets, with or without an enzyme, from excreta (24-h collections at 8 or 16 d) and ileal digesta (17 d). The objective was to discuss the merits and accuracy of sample source (excreta vs ileal digesta) and bird age for determining the feeding value of wheat and barley. The bioassay utilized 80% of a test cereal grain, 20% basal diet containing 1.1% acid insoluble ash marker, and fed with or without an enzyme to four pens of six male broilers from 4 to 17 d. A total of 138 wheat and 97 barley samples (with and without an enzyme) were tested in 15 and five bioassays, respectively. Within each wheat or barley bioassay two control wheat and barley samples were measured. The among-pens and between-assays CV for AME were calculated for these control samples, and correlation coefficients between the measures were calculated for the controls and for all of the 138 wheat and 97 barley samples included in the assays. For wheat samples, values for AME were lowest for excreta samples collected at 8 d, and similar for excreta and ileal digesta samples collected at 16 and 17 d, respectively. For barley samples, the three values were significantly different. The among-pens and between-assay CV were low for AME among both wheat and barley samples. Correlation coefficients between several measures of AME at 8 and 16 d were significant for the control samples with enzyme supplementation. When all samples were included in the analysis, correlation coefficients between AME measures were moderate to high. On the basis of accuracy, precision, and cost, these data favor measuring AME on excreta samples at 16 d of age. Comparisons of number of pens of broilers used to determine AME would suggest that much of the variability predicted with four pens of six broilers each could be achieved with three, and possibly two pens of six broilers each, thereby greatly increasing the capacity of the assay to screen large numbers of samples.

The effect of strain of broiler on physiological parameters associated with the ascites syndrome

Differences among eight commercial broiler strains in factors indicating susceptibility to ascites were investigated. Chicks from eight crosses were obtained from two hatcheries (one was obtained from both hatcheries to give a total of nine) and raised to 6 wk of age on commercially prepared rations containing 3,300 kcal/kg energy with 24% protein to 3 wk of age and 20% protein from 3 to 6 wk. Each cross was represented by four pens of 90 broilers each. At 21 and 42 d, groups of 20 birds per pen were weighed and feed consumption was measured in order to calculate the feed conversion ratio. At 21 and 42 d, a blood sample was taken from two birds per pen to determine the hematocrit value. These birds were killed and dissected to determine heart, liver, lung, and spleen weights. Lung volume was determined by water displacement. Significant differences were observed between crosses for all of the measures with the exception of feed conversion ratio and mortality. These differences were most prominent for hematocrit value, which is an initial adaptation to anoxia, suggesting that broiler lines could be chosen that resist anoxic environmental conditions.

Utilization of the sex-linked gene for imperfect albinism (S*ALS). 2. Yolk sac lipid utilization

The gene for sex-linked imperfect albinism (S*ALS) has been associated with reduced early growth and slow utilization of the yolk sac contents. Neonatal growth was studied using albino and nonalbino full siblings that were dissected at 2-d intervals from Day 16 of incubation to 7 d after hatch. Fatty acid composition of the yolk, yolk sac membrane, and liver was determined to study neonatal lipid metabolism. At hatch, albinos had similar BW and lower (P < 0.01) liver weights, suggesting reduced lipid transfer from the yolk sac during late incubation. Nonalbinos started gaining weight at 3 d after hatch, 1 d earlier than albino chicks. Albinos had reduced growth (P < 0.01), larger yolk sacs (P < 0.05), and similar (P > 0.05) yolk uptake from hatch to 7 d after hatch. Albino chicks also had lower body temperatures (P < 0.05) at 2, 4, and 6 d after hatch. Albinos had a slower rate of transfer of yolk lipids to the developing embryo in the last 2 d of incubation. The fatty acid composition of the yolk and yolk sac membrane was similar for both genotypes during the last 3 d of incubation, except for the level of stearic acid, which was higher (P < 0.05) for nonalbinos on Day 18 of incubation for both tissues and at 1 d after hatch for the yolk. The fatty acid composition of the livers of albinos and nonalbinos were similar (P > 0.05) during the neonatal period. For both genotypes, the hepatic level of oleic acid increased to Day 20 of incubation, remained constant to 1 d after hatch, and decreased sharply thereafter. The major difference between the genotypes was a slower rate of transfer of yolk lipids to the developing albino embryo in the last 2 d of incubation.

Utilization of the sex-linked gene for imperfect albinism (S*ALS). 1. Effect of early weight loss on chick metabolism

The sex-linked gene for imperfect albinism (S*ALS) has been associated with slow early growth in some trials but not in others. Albino (59) and nonalbino (73) chicks were raised to 3 d of age to study early growth. At 3 d of age, plasma beta-hydroxybutyrate (beta-HBA) levels were measured and the chicks were euthanatized and dissected to measure liver, gall bladder, and yolk sac weights. Fatty acids of the liver and the yolk sac were also analyzed. On average, albino chicks lost weight between hatch and 3 d of age and nonalbinos gained weight (-2.41 vs 0.74 g/d, P < 0.01). At 3 d of age, livers from albinos contained higher (P < 0.01) levels of docosahexaenoic acid than those of nonalbinos, likely reflecting the dependence on yolk sac nutrients of albinos and on dietary lipids of nonalbinos at this time. Albinos had lower body temperatures (P < 0.01), liver weights (P < 0.01) and gall bladder weights (P < 0.05), and heavier yolk sacs (P < 0.01) than did nonalbinos. Plasma levels of beta-HBA were higher (P < 0.01) for albinos than for nonalbinos. At similar body weights, chicks of both genotypes had similar body temperatures, gall bladder weights, and plasma beta-HBA levels. Linear regressions indicated that in albinos weight loss is associated with larger yolk sacs, smaller livers, larger gall bladders, lower body temperatures, and higher levels of beta-HBA. Yolk sac utilization seemed to be correlated with activation of the digestive system. The inability of starving chicks to use the yolk sac nutrients while lipolysis is taking place suggests that yolk sac absorption does not respond to lipolytic hormones. Because under certain conditions a large proportion of albinos (90% in this experiment) show the symptoms of the starve-out syndrome, the S*ALS gene could serve as a model for the study of this syndrome.

A method for separating sex-linked imperfect albino (S*ALS) and nonalbino embryos before hatch

The feasibility of using the sex-linked gene for imperfect albinism (S*ALS) to sex chicks during incubation by candling was studied. With this technique, the dark eye of nonalbino embryos can be positively identified. Two trials were performed. In a first trial, 66.5 and 89.5% of the 254 nonalbino and 210 albino chicks produced in four hatches were correctly identified by candling at 7 d of incubation. Of 191 eggs predicted to be nonalbinos, 22 were albinos, resulting in an overall accuracy of 88.5% for identification of nonalbino embryos. In a second trial, the accuracy of the technique from 7 to 10 d of incubation was evaluated. Increased age resulted in a tendency for lower accuracy, but candling at 8, 9, or 10 d of incubation allowed identification of a greater (P < 0.05) proportion of the nonalbino population than at 7 d of incubation. Candling at 8 d of incubation allowed identification of nonalbinos and albinos with an accuracy of 81.3 and 84.9%, respectively, suggesting that the ALS gene could be used to sex chicks during incubation when used in a sex-linked cross. This technique may prove advantageous to the laying industry because of savings of incubator and hatcher space. The males of commercial layer lines are normally killed at hatch. Reducing the number that hatch by eliminating them before 10 d of incubation could diminish animal welfare concerns.

Effects of sex-linked imperfect albinism (sal-s) in the chicken on the relationships of plasma concentrations of progesterone and 17 beta-estradiol with egg production

Effects of the sal-s gene for sex-linked imperfect albinism on the relationships of plasma concentrations of progesterone (P4) and estradiol (E2) with egg production were investigated during the laying period. Egg production of 17 albino and 16 nonalbino hens was recorded from 19 to 60 wk of age. Blood samples of these hens were taken between 1330 and 1500 h at 19 and 20 wk of age and every 4 wk until 60 wk of age. At 61 wk, blood samples were taken 6, 5, and 4 h before a midsequence ovulation. Plasma P4 and E2 were measured by RIA. There was no difference between genotypes in days to first egg (157.8 vs 158.1 d). Hen-day egg production of albinos was greater (P < 0.05) than that of nonalbinos in the 4-wk periods between 52 and 56 wk (83.8 vs 69.2%) and 56 and 60 wk (81.3 vs 64.3%). Egg production for the entire laying cycle was not different between genotypes (81.0 vs 73.0%, P = 0.08). Plasma P4 and E2 concentrations were not different between albino and nonalbino hens. From 28 to 60 wk of age, partial correlation coefficients between P4 and egg production, and E2 and egg weight were significant for albino hens (r = 0.15 and 0.16, respectively) but not for nonalbinos (r = -0.03 and -0.1, respectively), and age and P4 concentrations were negatively correlated for both albinos (r = -0.22, P < 0.01) and nonalbinos (r = -0.32, P < 0.01). Preovulatory levels of P4 in albino hens were higher (P < 0.05) than those in nonalbinos. Plasma E2 was higher in albinos than in nonalbinos 5 h before ovulation (P < 0.05). These data suggest that increased egg production of albino hens is associated with differences in P4 and E2 metabolism.

Ovarian morphology and follicular development in sex-linked imperfect albino (s(al)-s) and nonalbino hens before or after a forced moult

1. The effects of the s(al-s) gene on ovarian morphology and the development of ovarian follicles in old laying hens before and after a forced moult were investigated by measuring and weighing the ovaries and follicles. 2. The laying rate of albinos was higher than that of nonalbinos before the forced moult but not afterwards. Hierarchical follicles in albino hens were smaller than those of nonalbinos before but not after the moult. 3. Growth intensity of hierarchical follicles was greater in albino hens before the moult, suggesting that follicular maturation was more rapid, possibly explaining the higher egg production observed. 4. All differences between genotypes disappeared after the moult, suggesting that the state of the ovary before a moult is independent of that afterwards.

Effets des tensions sinusoïdales normales et des trains d'impulsions sur le comportement et la production des poules pondeuses

The effects of normal sinusoidal electrical voltages and impulses on laying hens between 23 and 48 wk of age were evaluated. One hundred and twenty hens were caged individually in six blocks of 20 animals each. Within each block, the treatments were distributed in a randomized complete blocks design. Electrical voltages of constant amplitude of 0–3 V, 4–6 V and 7–9 V were applied in exp. 1, 2 and 3, respectively. Voltage differences with random amplitudes of 0–9 V were applied at a frequency of one pulse every 10 s in exp. 4 and a frequency of two pulses every 10 s in exp. 5. In exp. 6, the hens were subjected to voltages of 12–18 V at a frequency of one pulse every 10 s. In exp. 7, hens were placed three per cage and received either 0 or 12 V with one pulse every 10 s. All voltages were applied between the metallic nipple drinker and the metallic cage. Daily water and feed intake, laying rate and behavior of the hens were measured. These voltages did not affect feed or water consumption, laying rate or egg quality. Frequency of eating and drinking behavior, time spent eating and drinking and time spent standing or sitting were not affected by the treatment. Although poor performance of farm animals is occasionally attributed to stray electrical voltages, in this experiment, voltage differences as high as 18 V had no effect on the hens' production and behavior. Key words: Laying hens, stray voltage, behavior, production performance

Production and quality of eggs from sex-linked imperfect albino (sal-s) and nonalbino (s+) hens kept under commercial conditions

The beneficial effects of the gene for imperfect albinism on egg production were investigated under commercial conditions. In one line (Line 8) but not in another (Line 3), hen-day egg production of albinos from 46 to 75 wk of age was higher than that of nonalbinos (76.1 vs 72.6%) resulting in higher overall hen-day (71.1 vs 69.3%, P < .08) and hen-housed (276.3 vs 263.6 eggs) egg production by albino hens. Egg production of Line 8 albinos was not different than that of one of two commercial strains (Strain A) included as a control (76.1 vs 75.6%, P > .05). In data from Lines 3 and 8 combined, sexual maturity of albinos was delayed by 3.0 d. Mortality was higher for albinos than nonalbinos (3.6 vs 1.8%) during the first 2 wk of brooding and lower for albinos (5.8 vs 8.9%) during the laying period. Eggs from albinos weighed less (53.8 vs 55.3 g), had smaller yolks (16.9 vs 17.6 g) and shells (5.16 vs 5.27 g), and firmer albumen (5.9 vs 5.6 mm). The results suggest that the gene produces beneficial effects on egg production under commercial conditions.

Effects of sex-linked imperfect albinism in the chicken (sal-c) on plasma luteinising hormone concentrations and early egg production

1. When measured before and after the onset of darkness, plasma LH concentrations in 40-day-old sex-linked albino pullets (sal-c) were slightly lower than those of nonalbinos (s+). 2. This finding prompted an experiment in which plasma LH concentrations were measured between 12 and 33 weeks of age when daylength was increased at 15 or 21 weeks. Egg production of the early and late maturing albino hens was measured. 3. Plasma LH concentrations overall and at 17 weeks were lower for albinos than for nonalbinos. In the early maturing group egg production of albinos was higher than that of nonalbinos. 4. Results suggest that increased egg production of albinos is not the direct result differences in plasma LH concentrations but may be a consequence of differences in the control of LH secretion.

Research note: the S(al)-c mutation in the chicken is not linked to Rous-associated virus-2 related DNA sequences

A male chicken heterozygous for a gene for sex-linked imperfect albinism (s(al)-c) was used to produce offspring in five dam families. The DNA from 23 offspring (22 females and 1 male) was cut with the restriction enzyme Sac1 and hybridized with a Rous-Associated Virus-2 probe to test for linkage between the gene and endogenous viral (ev) genes. In a second experiment, 15 albino and 15 nonalbino females resulting from 4 males mated to 11 females were studied with the enzymes Sac1 and BamHI. In the first experiment, 10 different ev genes were seen. These, plus seven additional bands were seen in the second experiment. The gene s(al)-c segregated independently of all ev genes, suggesting that it could be used for autosexing of chickens or in layer flocks without causing inherent problems previously associated with K, the gene for slow feathering, caused by essentially complete concordance between K and ev21.

Effects of light on melatonin and two enzymes leading to its production in albino (s(al-c)) and nonalbino chickens

A gene for sex-linked imperfect albinism in the chicken (s(al)) has been associated with increased egg production with an implication that environmental light may play a role. In this study, levels of melatonin and hydroxyindole O-methyltransferase (HIOMT) and N-acetyltransferase (NAT), two enzymes leading to melatonin production, were studied in young albino and nonalbino chickens in relation to the daily light cycle, and after 19 days of constant light or dark. Differences between genotypes were found in the levels of HIOMT activity in the pineals and retinas of birds kept in constant light for 19 days. Other measurements were not significantly different. This study would appear to show that the visual system of imperfect albino chickens reacts differently to light than that of nonalbinos, but not with changes in the daily cycle of plasma melatonin or in NAT activity, which is the enzyme primarily responsible for the control of the melatonin level in the body.

Differential environmental effects on lesions, early growth, and mortality of imperfect albino (Sal-c) chicks

A series of experiments investigated early pleiotropic effects of a gene for imperfect albinism (s(al-c) in a population of chickens at Jouy-en-Josas, France. An elevated incidence of lesions of the navel, hocks, and nares typical of imperfect albinos were seen on these chicks, confirming their existence in this population. Variations in hatching environment and the amount of light in the hatcher both implicated in contributing to the occurrence of lesions of the hocks and nares, but not to those of the naval. In two experiments, using batteries and cages, early growth was reduced among albinos and early mortality was increased. Significant genotype by environment interactions for weight at 4 days and growth to this time, but not thereafter, suggested that the effect is restricted to this time. Unfavorable environments were most deleterious to albinos. In a third experiment, conducted in floor pens, the gene had no effect on either early growth or mortality. There was no effect of the gene on the lesions, early growth, or mortality when carried by heterozygous males (s+/s(al-c)).

Phenotypic, embryonic, and neonatal effects of a gene for sex-linked imperfect albinism (Sal-s) in chickens

Gross phenotypic observations, histology, and tissue culture showed that the gene for sex-linked imperfect albinism that occurred at the University of Saskatchewan (Sal-s), allows a small amount of melanin pigment to be deposited in eyes and feathers. Melanin pigment accumulates in retinal pigment epithelial and cultured neural crest cells, but neural crest cells pigmenting the feathers transfer their pigment as it is produced, and this is seen as a constant amount of color in successive generations of feathers. Despite differences from early reports, it would appear that the phenotype produced by Sal-s is essentially the same as that produced by other Sal mutations. Albinos have a high incidence of lesions in the regions of the navel, the hocks, and the nares, similar to those associated with other hypomelanic mutations in the chicken. Yolk contents appear to be used more slowly by albinos late in incubation. The increased size of the yolk sacs probably contributes directly to producing the navel lesions and indirectly to variation in hatch weight. Albinos have small bursae of Fabricius, reduced hatchability, and early growth.