Rearing photoperiod and abrupt versus gradual photostimulation for egg-type pullets

1. Lohmann White and Lohmann Brown egg-type hybrids were reared on 6-, 8-, 10- or 12-h photoperiods, transferred to 12.5 h at 18 weeks and then given weekly increments to reach 14 h at 21 weeks. In a second experiment, Lohmann White pullets from the same rearing facility were transferred abruptly to 14 h at 18 weeks. 2. Body weight gain and feed intake to 6 and 18 weeks were positively correlated with rearing photoperiod in both breeds. Mortality to 18 weeks was unaffected. 3. Whether the photoperiod was increased abruptly or in a series of increments, Lohmann White pullets reared on 6 or 8 h matured 4 to 6 d later than pullets reared on 10 or 12 h. Rearing day-length had little effect on sexual maturity in Lohmann Brown pullets. 4. In both genotypes and each experiment, egg numbers, egg weight and shell strength increased with rearing photoperiod. Feed intake in the laying period was not significantly affected by rearing day-length, but a meta-analysis of all data showed a significant, though small, increase in adult feed intake with rearing photoperiod. Despite Lohmann White birds reared on 6 and 8 h having lower body weights throughout the laying period, they had larger body weight gains between 18 and 70 weeks than those reared on 10 or 12 h. There were no clear effects of rearing photoperiod on albumen height or mortality. 5. The heavier eggs and stronger shells of the birds reared on the longer day-lengths were correlated with heavier body weights at 18 weeks, and the superior egg numbers and higher feed intake were associated with age at sexual maturity.

Green Light During Rearing Does Not Significantly Affect the Performance of Egg-Type Pullets in the Laying Phase

Lohmann White pullets were reared in cages and illuminated with 8 h of white light at 2.6 lx or green light at 3.0 lx from commercial incandescent lamps. They were transferred to individual cages and the photo-period was increased to 14 h of white light at 15, 17, or 19 wk. Pullets grown under green light had significantly lighter BW at 6 wk than did birds grown under white light, but BW were similar at 12, 15, 17, and 19 wk. Although mean age at first egg was 1 d earlier for birds reared under white light, there were no significant differences between the 2 groups for any other performance trait. These findings do not support lamp manufacturers' claim that green fluorescent light during rearing improves performance. As expected, the birds photostimulated at 17 wk matured after the 15-wk birds but before the 19-wk birds. Subsequently, the 15-wk birds laid more eggs to 71 wk, but had a lower mean egg weight and thinner shells (higher deformation) than the other 2 groups. Albumen height and feed intake were similar for all 3 photo-stimulation ages.

Balancing science versus societal issues in poultry nutrition

Abstract

Scientific rational exists for the formulation of poultry diets. However, this practice is now being impacted, and sometimes overshadowed, by societal issues that for the most part are consumer-driven emotional decisions lacking sound scientific rationale. Nevertheless, the adage that 'perception is reality' certainly applies to current poultry feeding practices and so nutritionists have had to modify feed formulations to accommodate not only science-based needs but also these societal concerns. The impact of societal issues is influencing decision-making from farm production through to retail distribution of poultry products. In fact, some of these social issues have been driven by retailers who see marketing opportunities that are now impacting the entire production chain. Perhaps the single largest factor to impact poultry production and poultry nutrition over the last 10 years has been the mandatory or voluntary removal of antibiotics from feeds. Consumers are becoming more concerned about the nutrient content of foods and how this impacts their health. Over the last few years there have been various strategies aimed at manipulating poultry products, and especially eggs, with a view to improving human health. For the animal and food industries, functional foods represent an opportunity for increased revenue while concomitantly providing the consumer with meaningful contributions of various nutrients that positively impact human health. Environmental issues are also impacting poultry feed formulation, as is the limited supply of energy-rich ingredients as a consequence of government policies to reduce dependence on imported oil by fermenting traditional ingredients such as corn.

Pre-endoscopic proton pump inhibitor therapy reduces recurrent adverse gastrointestinal outcomes in patients with acute non-variceal upper gastrointestinal bleeding

BACKGROUND

Proton pump inhibitors (PPIs) following endoscopic haemostasis reduce rebleeding rates in patients with high-risk acute non-variceal upper gastrointestinal bleeding. Many advocate the use of PPIs prior to endoscopy, although its incremental benefit is unproven.

AIM

To determine if providing PPIs before endoscopy reduces adverse gastrointestinal outcomes in acute non-variceal upper gastrointestinal bleeding patients.

METHODS

We performed a retrospective review to identify patients presenting to two tertiary care centres with acute non-variceal upper gastrointestinal bleeding between 1999 and 2004. Subjects receiving PPI therapy before endoscopy were compared with those not receiving pre-endoscopic PPI therapy. The primary outcome measure was the development of any adverse bleeding outcome (rebleeding, surgery for control of bleeding, in-hospital mortality, readmission within 30 days for acute non-variceal upper gastrointestinal bleeding).

RESULTS

385 patients were included in our study [132 (12 intravenous/120 po) pre-endoscopic PPI vs. 253 no pre-endoscopic PPI]. Patients receiving pre-endoscopic PPI therapy were significantly less likely to develop adverse outcomes compared with those not given pre-endoscopic PPIs (25% vs. 13%, P = 0.005). Rebleeding, upper gastrointestinal surgery, mortality and length of hospital stay were also significantly lower in patients receiving pre-endoscopic PPI.

CONCLUSIONS

The use of PPIs before endoscopy significantly reduces the risk of developing adverse gastrointestinal outcomes in patients with acute non-variceal upper gastrointestinal bleeding. Future studies are required to better characterize this relationship.

Effect of arginine:lysine ratios and source of methionine on growth and body protein accretion in acutely and chronically heat-stressed broilers

The effect of Arg:Lys, Met source, and time of exposure to heat stress on growth and body protein accretion was tested in acutely heat-stressed (AHS) or chronically heat-stressed (CHS) broilers. Ross 308 1-day-old chickens were raised under normal brooding conditions from 1 to 25 d of age and were then suddenly moved to 32 degrees C (AHS), whereas another group was kept at constant high temperatures throughout the grow-out period (32 degrees C; CHS). From 26 to 33 d of age, both groups were therefore at 32.8 +/- 1.0 degree C. Two rooms were used per environmental treatment. A basal diet deficient in TSAA was supplemented with L-Arg monohydrochloride to achieve Arg:Lys ratios of 0.95 and 1.40. Diets were supplemented with either L-Met, 2-hydroxy-4-(methylthio) butanoic acid (HMB), or DL-Met (DLM) to a level of TSAA 5% lower than requirements. Each Arg:Lys and Met source combination was diluted with a N-free diet to achieve graded levels of CP (0.0, 3.5, 7.0, 10.5, 14.0, and 17.5% CP) and fed to 18 replicates of 3 chickens (3 replicates per level). Treatment effects were obtained by the slope-ratio technique using average daily BW gain and body CP deposition as dependent variables and protein intake as the independent variable. Protein utilization remained unaffected by Met source when fed at high Arg:Lys for birds under AHS and CHS (P > 0.05). However, lower protein utilization was observed in birds fed L-Met in low Arg:Lys compared with those fed DLM (P < 0.05). Birds fed HMB at low Arg:Lys utilized dietary protein better than those fed L-Met only under CHS conditions (P < 0.05). Protein utilization for birds fed HMB was similar to that of birds fed DLM in all instances. It was concluded that Arg:Lys, Met source, and time of exposure to heat stress affected protein utilization in hyperthermic birds.

Efficiency of utilizing ileal digestible lysine and threonine for whole body protein deposition in growing pigs is reduced when dietary casein is replaced by wheat shorts

To determine the effect of dietary inclusion level of wheat shorts (WS; a high nonstarch poly-saccharide-containing feed ingredient) and casein (CS; a control) on the efficiency of utilizing ileal digestible Lys (kLys) and Thr (kThr) for whole body protein deposition (PD) in the growing pig, 2 separate N-balance studies were conducted with either Lys or Thr as first-limiting AA in cornstarch-based diets. For the Lys study, a basal diet (L-basal) was formulated to contain 0.24 g of standardized ileal digestible (SID) Lys per MJ of DE, to which 0.095 or 0.19 g of SID Lys per MJ of DE were added using either CS (L-CS2 or L-CS3, respectively) or WS (L-WS2 or L-WS3, respectively). A sixth diet was evaluated that was similar to L-CS3 but to which 6% pectin (L-pectin) was added as a source of soluble nonstarch polysaccharides. For the Thr study, the basal diet (T-basal) was formulated to contain 0.14 g of SID Thr per MJ of DE, to which 0.055 or 0.11 g of SID Thr per MJ of DE were added from CS (T-CS2 or T-CS3, respectively) or from WS (T-WS2 and T-WS3, respectively). A sixth diet was evaluated that was similar to T-CS3 but to which 6% pectin was added (T-pectin). Increasing SID Lys intake from CS did not influence kLys for PD (P > 0.10), whereas increasing SID Lys intake from WS reduced kLys for PD (P = 0.001; 89 vs. 79%). Inclusion of 6% pectin had no effect on kLys for PD (P > 0.10). Increasing SID Thr intake from CS also did not influence kThr for PD (P > 0.10), whereas kThr for PD was reduced at the greatest dietary inclusion level of WS (P < 0.001; 90 vs. 77%). Pectin inclusion had no effect on kThr for PD (P > 0.10). The inefficiency of utilizing ileal digestible Lys intake for PD may be attributed to nonreactive Lys in WS. The negative impact of including high levels of WS in the diet of pigs on kThr seems to be associated with fiber content of WS; it was not related to increased endogenous ileal AA losses at the distal ileum. The impact of dietary AA source on the use of ileal digestible Lys and Thr for PD, or other body functions, is substantial and should be considered in the formulation of pig diets. Further research is warranted to elucidate the mechanisms contributing to substantial dietary effects on Thr use for PD.

Use of apparent transverse quantitative ultrasonography to assess skeletal integrity in layers

Although there are several techniques currently available to assess skeletal integrity in live birds, few offer important features for application in a commercial setting, offering ease of use and moderate cost. Quantitative ultrasonography (QUS) is an established technique for diagnosis of osteoporosis in humans and horses that has potential application for layers. An OmniSense 700S quantitative ultrasonometer was evaluated for use with Single Comb White Leghorn hens. Humeral QUS values (m/s) were measured in a series of experiments using a total of 144 Shaver White hens. Significant correlations (P < 0.01) were observed among sequential QUS measurements taken on the same bird at 54, 60, and 66 wk of age. At the completion of the studies (66 wk of age), the left and right humeri were excised, cleaned, and rescanned. Postmortem QUS data from left and right humeri were related (R2 = 0.72, P < 0.0001), although future studies may need to consider both sides of the skeleton to account for asymmetry conditions. Ultrasound data collected from live hens at 66 wk of age correlated well with postmortem QUS data (R2 = 0.80, P < 0.0001). Quantitative ultrasonography did not correlate with humeral bone-breaking force measured postmortem. Bones from live hens, surrounded by tissue thicker than 4 mm, could not be read by the QUS probe.

Concentrations of putrescine, spermidine, and spermine in duodenum and pancreas as affected by the ratio of arginine to lysine and source of methionine in broilers under heat stress

An experiment was designed to investigate the effect of Arg, Lys, Met, and environmental temperature on broiler performance and associated changes in duodenal and pancreatic polyamines. Two groups of 26-d-old Ross male broilers raised under thermoneutral (TN) conditions were reallocated to 4 rooms kept at heat stress (HS) or TN. Birds were fed equimolar amounts of 2-hydroxy-4-(methylthio) butanoic acid (HMB) or DL-Met (DLM) at requirement levels with Arg:Lys at 0.95 or 1.40. Twelve replicates of 4 birds were offered each diet ad libitum. Body weight gain, efficiency of dietary CP accretion (CPE), feed intake, and feed conversion ratio were ascertained from 26 to 33 d and from 34 to 47 d of age. One bird per cage was killed at 33 and 47 d, and samples of duodenum and pancreas were assayed for putrescine, spermidine, and spermine (Spm), together with estimates of duodenal villus height. From 26 to 33 d, birds fed HMB performed better than those fed DLM, but only at TN conditions. From 34 to 47 d, feeding HMB tended to optimize CPE when added to diets high in Arg. However, lower CPE was obtained when HMB was added to low-Arg diets, whereas birds fed DLM were unaffected by these treatments (P < 0.10). Methionine source, Arg:Lys, or both affected the concentrations of duodenal and pancreatic polyamines, with some changes correlating with performance variables during HS (P > 0.05). It was found that HS caused lower tissue spermidine (P < 0.001) and higher pancreatic Spm (P = 0.08) from 34 to 47 d. Putrescine concentrations were affected by diet and HS, depending on tissue and experimental period. Pancreatic Spm correlated negatively with changes in CPE influenced by Arg:Lys by Met source interaction in chronically heat-stressed birds. The possible association between polyamine metabolism and some of the effects of the Arg:Lys by Met source interaction observed in chronically stressed birds deserves further investigation.

Role of serine in maintaining blood glucose levels o f broilers fed all-vegetable diets (R3)

Supplementing an all-vegetable diet with milk-powder, casein or serine resulted in increased blood glucose. Birds fed serine were also heavier than those fed a conventional diet or an unsupplemented all-vegetable diet. Birds fed all-vegetable diets may be more prone to hypoglycemia. Key words: Broiler, blood glucose, spiking mortality syndrome

Effects of Feeding Grains Naturally Contaminated with Fusarium Mycotoxins on Performance and Metabolism of Broiler Breeders

A study was conducted to investigate the effects of feeding grains naturally contaminated with Fusarium mycotoxins on performance and metabolism of broiler breeders. Forty-two 26-wk-old broiler breeder hens and nine 26-wk-old roosters were fed the following diets: (1) control, (2) contaminated grains, and (3) contaminated grains + 0.2% polymeric glucomannan mycotoxin adsorbent (GMA) for 12 wk. The major contaminant was deoxynivalenol (12.6 mg/kg of feed), with lesser amounts of zearalenone and 15-acetyl-deoxynivalenol. Feed consumption and BW were not affected by diet. The feeding of contaminated grains did not significantly affect egg production. Decreased eggshell thickness was seen, however, at the end of wk 4, and dietary supplementation with GMA prevented this effect. There was no effect of diet on other egg parameters measured. There was a significant increase in early (1 to 7 d) embryonic mortality in eggs from birds fed contaminated grains at wk 4, but mid- (8 to 14 d) and late- (15 to 21 d) embryonic mortalities were not affected by diet. There were no differences in newly hatched chick weights or viability. The ratio of chick weight to egg weight was not affected by the feeding of contaminated grains. Weight gains of chicks fed a standard broiler starter diet at 7, 14, and 21 d of age were not significantly affected by previous dietary treatments for the dam. It was found that rooster semen volume and sperm concentration, viability, and motility were not affected by the feeding of contaminated diets. There was no effect of diet on the relative weights of liver, spleen, kidney, and testes. The feeding of contaminated grains decreased antibody titers against infectious bronchitis virus at the end of wk 12, and this was prevented by dietary supplementation with GMA. There was no effect of the diet on serum antibody titers against Newcastle disease virus. It was concluded that the feeding of blends of grains contaminated with Fusarium mycotoxins could affect performance and immunity in broiler breeder hens.

Effect of arginine:lysine and methionine source on amino acid digestibility and response to dietary electrolytes in chronically or acutely heat-stressed broilers

In two experiments, the effects of arginine:lysine, NaHCO3 and methionine source on performance and amino acid digestion of heat-stressed broilers were studied. In exp. 1, corn/soy diets with argine:lysine (Arg:Lys) of 1.10, 1.25 and 1.40 were fed from 21 to 42 d. Diets were supplemented with 2-hydroxy-4-(methylthio)-butanoic acid (HMB) or DL-Methionine (DLM) with NaHCO3 at 0 or 1.04%. Ten replicates per treatment of four birds per cage were maintained at 31.7 ± 0.9°C. From 21 to 28 d weight gain (BWG), feed consumption and feed-to-gain (FCR) were unaffected by diet treatment. Methionine source did not influence bird performance (P > 0.05). However, from 35 to 42 d, when diets were supplemented with NaHCO3, BWG and FCR of birds fed DLM were compromised when offered diets with Arg:Lys at 1.40. In diets devoid of NaHCO3, increasing Arg:Lys to 1.25 impaired BWG and FCR for broilers fed DLM, although effects disappeared when more Arg was used. Performance of birds on HMB was mostly unaffected by Arg:Lys or NaHCO3 except when fed diets void of NaHCO3 with Arg:Lys of 1.40, when FCR was impaired. In exp. 2, broilers were maintained at thermoneutrality (TN) reaching 20°C at 33 d. Other birds were at 31°C throughout, representing chronic heat stress (CHS), while a third group changed suddenly from 20 to 31°C at 25 d representing acute heat stress (AHS). Birds within each environment were housed in one of two rooms with eight replicates of four birds per treatment. At 25 d, birds were fed Arg:Lys of 0.95 or 1.40 with DLM supplemented at requirement. Birds fed Arg:Lys of 1.40 were also offered diets with synthetic L-methionine (L-Met). Adding L-Met to high Arg diets during CHS significantly depressed ileal digestibility of all amino acids (P < 0.05). It is concluded that chronic heat stress can affect the digestibility of amino acids, and that this effect may impact performance. Key words: Broilers, methionine, arginine, heat stress, digestibility, sodium bicarbonate

Use of axial X-ray microcomputed tomography to assess three-dimensional trabecular microarchitecture and bone mineral density in single comb white leghorn hens

Axial x-ray microcomputed tomography is a cost-effective technique with the potential to assess bone mineral density (mg/cc) in both cortical and cancellous bone in Single Comb White Leghorn hens. The technique requires little sample preparation and involves relatively simple data processing. The system described in this research is based on compact fan-beam type tomography, using a tungsten-anode x-ray tube with a relatively small focal spot (approximately 5 microm), coupled with a high-resolution x-ray detector system (approximately 10 microm). To produce a real 3-D data set using microcomputed tomography, x-ray projection views were acquired at 720 equally spaced angular positions (0.5 degrees) around the object of interest. These groups of views were then used to reconstruct a computed tomography image. A test grid with orthogonal test lines was used to calculate bone volume and bone surface. From these calculations, parallel plate equations were used to derive trabecular architectural parameters such as average trabecular plate thickness and average trabecular plate separation. Three-dimensional microarchitecture was evaluated using specialized stereological analysis software. Significant relationships between apparent bone mineral density (mg/cc) and 3-D structure were observed in femoral specimens from 66-wk-old Single Comb White Leghorn hens.

Effects of acute versus chronic heat stress on broiler response to dietary protein

Two experiments were conducted to determine broiler response to dietary protein during short (1 wk) or prolonged (>3 wk) heat stress (HS). In experiment 1, 21-d-old birds were kept at 20.3 degrees C (thermoneutral; TN), 27.3 degrees C (medium temperature; MT), or 31.4 degrees C (high temperature; HT) and fed diets with 18, 20, 23, or 26% CP for 21 d. Each treatment consisted of 2 blocks of 3 replicates of 15 birds. In experiment 2, broilers were fed diets with 18 or 26% CP or fed ad libitum 2 diets with 10 or 30% CP. Birds were kept at TN (23.5 degrees C) or slowly introduced to HS from 7 to 14 d of age and kept at HT thereafter (chronic; CHS; 29.4 degrees C), and a third group was moved to HT at 21 d (acute HS; AHS; 29.4 degrees C). There were 16 replicates of 4 chickens per treatment distributed in 2 blocks. Performance, body composition, and protein deposition were ascertained from 21 to 28 d and from 28 to 42 d (short and prolonged exposures, respectively). Feeding high protein diets in experiment 1 resulted in linear improvements in body weight gain and feed:gain (P < 0.001) for MT and HT birds, whereas TN birds exhibited a linear (P < 0.001) response to protein. Feed intake declined as CP increased for HT birds during the third week of the study (P < 0.05). In trial 2, better performance was always observed in TN birds. HS depressed performance, although feeding high CP partially ameliorated this effect under AHS and CHS. Regardless of temperature, choice-fed birds selected high protein diets (mean 25.6% CP) and performed similarly to those fed 26% CP. CHS birds showed similar performance to those under AHS. Efficiency of protein deposition was unaffected (P > 0.05). Level of HS and duration of hyperthermia may determine the response of birds to dietary protein. Discrepancies between the 2 studies in response of birds to protein found after prolonged exposure to HS are discussed in view of the differences in levels of certain amino acids used within each experiment.

Effect of butyric acid on the performance and carcass yield of broiler chickens

Short-chain fatty acids such as butyrate are considered potential alternatives to antibiotic growth promoters. The efficacy of butyric acid on performance and carcass characteristics of broiler chickens was tested in two studies. The effect of dietary butyrate on the ability to withstand coccidial oocyte challenge also was investigated. In experiment 1, male broiler chickens were fed diets supplemented with 0 or 11 ppm virginiamycin or 0.2 or 0.4% butyric acid (as mono-, di-, and triglyceride). In experiment 2, broilers were fed bacitracin methylene disalicylate or 0.1 or 0.2% butyric acid. In another trial, birds vaccinated against coccidiosis were challenged with oocytes at 21 d and examined 6 d later. In experiment 1, diet treatments had no effect on body weight gain. Feed intake of the birds fed 0.4% butyric acid was decreased (P < 0.01) compared with birds fed the nonmedicated diet during the starter period, whereas birds fed 0.2% butyric acid had similar feed intake to the control birds. In experiment 2, diet treatments did not affect the performance of broiler chicks while carcass weight and breast meat yield increased (P < 0.01) in birds fed 0.2% butyric acid. With oocyte challenge, birds that had received butyric acid before challenge showed higher growth rate following the challenge compared with birds that received nonmedicated feed. Bacitracin decreased (P < 0.05%) duodenal villi crypt depth, whereas villus length was similar in birds fed butyric acid or the nonmedicated control diet. These results show that 0.2% butyric acid can help to maintain the performance and carcass quality of broilers, especially in vaccinated birds challenged with coccidiosis.

Utilization of metabolizable energy by young broilers and birds of intermediate growth rate

An experiment was conducted to study the utilization of ME by 3 strains of birds with different growth rates: commercial broilers, Plymouth Barred Rocks, and Leghorns. Birds were fed a diet providing 3,100 kcal of ME/kg and 20% CP from 0 to 42 d. ME and nitrogen balance were determined from 10 to 15, 23 to 28, and 37 to 42 d. Energy retained (ER) as fat (ERF) and protein (ERP) were derived from body analyses for each period and group of birds. ERF and ERP were obtained as the difference in values at the end of each period and their respective predicted values based on BW at the beginning of the period. ER, ERF, and ERP per unit metabolic BW were significantly different for broilers vs. the other 2 strains in all periods (P < 0.001). Heat production and ER increased significantly (P < 0.01) for all groups. There was a significant decrease in HP (P < 0.001) over time with no change in ER, ERF, or ERP over time. Age appeared to have no significant effect on ERF/ME regardless of strain. Estimation of maintenance requirements as a function of BW0.75 vs. BW0.60 showed that requirements for broilers per kilogram of BW0.75 are 8% lower compared with estimates based on BW0.60. It seems that energy requirements for maintenance has been underestimated for younger or smaller birds and implies greater apparent efficiency for growth. Because ME intake for maintenance requirements represents a large portion of the ME intake, the results from this experiment could be considered in calculation of energy requirements for growing broilers.

Lysine requirements of young broiler chickens are affected by level of dietary crude protein

Growth and body nitrogen and fat deposition in response to dietary lysine were assessed in chicks to 21 d of age when fed dietary crude protein (CP) at 170, 210, 250 or 290 g kg-1 diet. Response variables were evaluated using linear and quadratic regression, and linear-plateau models. In all cases, a better fit was observed with quadratic regression and linear-plateau models. Weight gain, F:G, and body nitrogen and fat deposition plateaued as dietary lysine was increased regardless of CP. Lysine requirements for weight gain to 21 d were significantly different when comparing 170 vs. 210 and 210 vs. 250 g CP kg-1 diets, although no differences were found when 250 and 290 g CP kg-1 were fed. Feed efficiency and body nitrogen responded in a similar manner to diet CP and lysine levels. Dietary lysine requirement increased as CP increased (170 vs. 210, and 210 to 250 g kg-1), although lysine requirement was unaffected when 250 or 290 g CP kg-1 diets are used. The requirements for lysine at low CP levels are better expressed as a percentage of CP. However, when dietary CP intake no longer limits growth, lysine needs should be specified as a diet percentage. Key words: Lysine, broiler chickens, nitrogen

Rearing and laying performance following various step-down lighting regimens in the rearing period

It is frequently recommended that commercial laying pullets are reared on step-down lighting regimens, rather than on constant short photoperiods, to help achieve BW targets during rear and optimal performance in lay. To evaluate the effectiveness of this strategy, Shaver White pullets were maintained on 8-h day lengths or given a step-down lighting regimen from 23 to 8 h over periods of between 1 and 15 wk. Other pullets, which were initially maintained on 8 h of light, were given an abrupt increase in day length prior to transfer to step-down lighting at various ages between 1 and 13 wk. All birds were given abrupt increments to 14 h at 18 wk and to 16 h at 20 wk to stimulate appetite and optimize uniformity of sexual development. Body weights at 6 and 12 wk were generally heavier and cumulative feed intakes to 6 wk were greater for birds given step-down lighting from 1 wk of age than for constant 8-h controls or birds given an initial period on 8-h day lengths prior to step-down lighting. Sexual maturity for birds on step-down lighting from 1 wk and for those on < or =5 wk of 8-h day lengths before transfer to step-down lighting was delayed by about a week compared with the constant 8-h controls or birds on 9 wk or more of 8-h day lengths before step-down lighting. These delays in sexual maturity resulted in a lower BW at 18 wk. Body weight uniformity at 18 wk was improved by step-down lighting, whether it was given from 1 wk or after a period of 8-h day lengths. Despite step-down lighting resulting in larger initial feed intakes and improved early growth, there was no significant improvement in egg numbers, egg weight, egg mass, feed intake, shell deformation, or albumen height compared with constant 8-h controls. Differences in egg output were generally the consequence of photoperiodically induced changes in sexual maturity.

Comparing efficiency of metabolizable energy utilization by rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar) using factorial and multivariate approaches

A study was conducted to compare utilization of ME for growth vs. maintenance in rainbow trout and Atlantic salmon. Fish were hand-fed to satiation one of four isoenergetic diets (DE = 20 MJ/kg, as-fed basis) with different digestible protein (DP) to DE ratios (24, 22, 20, and 18 g/MJ). Intake of ME (kJ/d), energy deposited as protein (PD, kJ/d), and energy deposited as lipid (LD, kJ/d) were determined by a comparative slaughter technique. Data were analyzed by a factorial approach or by multivariate analysis of PD and LD on ME. Maintenance energy requirements (ME(m)) and efficiency of ME utilization for PD (k(p)) and LD (k(f)) were estimated with both approaches. For the multivariate analysis, an additional parameter, the fraction of ME intake above maintenance used for PD (X) was defined as linear function of BW, with slope (d) and intercept (c) estimated simultaneously with the above parameters. Estimates were highly dependent on the approach and assumptions used. The ME(m) and k(p) values were higher and less accurate with the factorial approach than with multivariate analysis. The factorial approach estimated unrealistic k(f) values (k(f) > 1). With the multivariate analysis, ME(m) did not differ between species (20 kJ x d(-1) x kg(-0.8)). On the other hand, k(p) was significantly higher (e.g., 0.52 +/- 0.06 vs. 0.43 +/- 0.06; P < 0.05) for salmon than for trout and independent of diet, but k(f) was 0.81 (+/-0.13) regardless of species or diet. The ME intake above ME(m) used for PD (c) was higher in salmon than trout (57 vs. 55%; P < 0.05). The change in partitioning of ME for PD due to the change in BW was negative for trout (d = -0.18), but positive for salmon (d = 0.16). The d values agreed well with the increase of LD:PD ratio with BW for trout and the decrease of LD:PD with BW for salmon, which may have been related to the maturation status of this fish and the associated loss of body lipid observed by maturing salmon. In conclusion, ME(m) and cost of LD were similar for rainbow trout and Atlantic salmon, but the cost of PD was lower for salmon than for trout.

Muscle (pectoralis major) protein turnover in young broiler chickens fed graded levels of lysine and crude protein

An evaluation of muscle (pectoralis major) protein turnover using the phenylalanine flood dose technique was assessed in broiler chicks fed graded dietary lysine levels with CP at 170, 210, 250, and 290 g/kg diet. Chicks at 21 d old were injected with 1 mL/100 g BW of a phenylalanine solution (120 micromol L-[ring-2H5)]-phenylalanine). Muscle protein gain was assessed in chicks at 19 and 23 d of age. No differences were found in weight gain at lysine levels higher than 1.22% of the diet. Dietary lysine levels affected fractional synthesis rate (FSR, %/ d) of muscle with 170 and 210 g of CP/kg diet but not with 250 and 290 g of CP/kg. However, there was increasing FSR with increasing diet lysine levels at 290 g of CP/ kg. Breast muscle protein deposition (absolute growth rate, AGR, mg/d) reached a plateau with 1.22% dietary lysine at CP levels of 170,210, and 290 g/kg diet, confirming the observation on gross muscle weight. In terms of absolute synthesis rate/AGR with minimal absolute breakdown rate (ABR), the diet containing 210 g of CP/kg with 1.22% lysine was the most appropriate for chicks to 21 d. Levels of lysine influenced protein synthesis more so than protein degradation. These data suggest that both protein synthesis and breakdown increase at levels of dietary lysine and CP above those required for maximizing growth.

Enrichment of Eggs with Lutein

Lutein is being considered as a nutrient for prevention of macular degeneration in the aging population. Two experiments were designed to study the transfer efficiency of lutein from the layers' diet into the egg. In experiment 1, laying hens were fed corn-soy diets supplemented with 0, 125, 250, 375, 500, 625, 750, or 1000 ppm of lutein. After 30 d, eggs were collected and assayed for lutein. In a second study, layers were fed corn-soy diets or diets containing corn gluten meal and alfalfa, with or without added flaxseed. Diets in experiment 2 were supplemented with 0, 125, 250, or 500 ppm of lutein. Adding lutein to the layers' diet resulted in a significant (P < 0.01) increase in Roche color score of yolk within 7 d of supplementation. In experiment 1, lutein was transferred into the yolk (P < 0.01) increasing from a basal level of 0.3 mg to 1.5 mg/60 g of egg. However, there was no significant (P > 0.05) increase in yolk lutein with diet supplements >375 ppm. In the second experiment, using corn gluten meal and alfalfa further increased lutein content that leveled off at 2.2 mg/60 g of egg with a diet supplement of 500 ppm of lutein. Adding flax to these diets seemed to depress yolk lutein content. Yolk lutein content can be increased, although further studies are needed to investigate the major decline in transfer efficiency seen with higher levels of dietary supplementation.

The inadequate smear: does it matter?

The objective of this study was to quantify the incidence of underlying cervical intraepithelial neoplasia (CIN) among women referred for colposcopy with three consecutive inadequate smears. The design was a retrospective cohort study analysing data from a regional colposcopy database at Cervical Screening Wales. Women who were referred to all the colposcopy clinics in Wales with three consecutive inadequate smears, the third inadequate smear being taken between 1 April 2001 and 31 March 2002 constituted the study population. The results of the fourth smear taken at the colposcopy clinic after three consecutive inadequate smears, the worst biopsy results from any of the subsequent colposcopies and the relationship between the result of the fourth smear taken at colposcopy clinic and any histology result were the main outcome measures. The accuracy of the colposcopic opinion was also examined. Of the 433 women identified as having been referred because of three consecutive inadequate smears, 302 were linked to either a subsequent smear and/or a biopsy result. An adequate smear result was available for 85% of these women when the smear was taken in the colposcopy clinic; 77% were reported as negative and 8% were abnormal. Of the 347 women seen in the colposcopy clinic, high-grade CIN was seen in 3% and low-grade lesion in 8%. The sensitivity and specificity of the fourth inadequate smear test in predicting underlying CIN were 15% and 84% respectively, with a positive predictive value of 8%. The sensitivity and specificity of colposcopy in predicting histological CIN among patients with three inadequate smears was 70% and 49%, respectively, and the positive predictive value was 44%. This study raises the question as to whether three consecutive inadequate smears should be considered as an indication for colposcopy, or merely for a further smear to be taken in circumstances where there is a greater likelihood getting an adequate result.