Effect of Dietary Crude Protein and Lysine on Feather Growth in Chicks to Twenty-One Days of Age

A study was conducted to evaluate feather development in male broiler chickens fed variable levels of dietary CP and lysine. Diets contained 170, 210, 250, or 290 g of CP/kg with 0.86, 1.22, 1.34, or 1.46% lysine, each being fed to 2 replicate groups of 4 chicks. Dietary CP per se had a significant effect on feather weight and feather nitrogen gain. Increasing dietary CP from 170 to 250 g of CP/kg of diet increased feather weight and feather nitrogen gain. No differences were found at higher dietary CP levels. Dietary lysine levels from 0.86 to 1.46% did not affect feather weight, feather nitrogen gain, or feather:body weight in male chicks to 21 d. However, feather weight and feather nitrogen gain decreased as lysine increased in diets with 170 and 210 g of CP but not with 250 or 290 g of CP/kg. Percentage of total feather nitrogen was also influenced by the level of dietary lysine in diets containing 210 and 250 g of CP/kg. Feather development was more influenced by dietary CP per se than by levels of lysine.

Changes in light intensity during the rearing period can influence egg production in domestic fowl

1. A total of 240 Shaver White and 240 ISA Brown pullets that had been reared in multi-bird cages on a 10-h photoperiod, and maintained at a light intensity of 3 or 25 lux, or changed from 3 to 25 lux or from 25 to 3 lux at 9 or 16 weeks of age, were moved into individual-bird cages at 20 weeks and transferred to 15-h photoperiods at 25 lux. 2. In both breeds, birds transferred from 3 to 25 lux at 16 or 20 weeks laid significantly more eggs than birds maintained on the brighter intensity from one day or increased to it at 9 weeks. 3. Mean egg weight, shell deformation, albumen height, feed intake and body weight gain in lay were not significantly affected by the light intensity treatments during the rearing period. There was, however, a small, but significant, negative correlation of egg numbers with mean egg weight, although this only partially explained the difference in egg numbers. The differences in egg production were unrelated to rate of sexual maturation.

Changes in light intensity can influence age at sexual maturity in domestic pullets

1. Shaver White and ISA Brown pullets were reared to 140 d in groups of 8 in cages on a 10-h photoperiod of incandescent light and maintained at an illuminance of 3 or 25 lux, or transferred from 3 to 25 lux or from 25 to 3 lux at 63 or 112 d of age. 2. There was no significant difference in sexual maturity, measured as eggs per 100 bird.d at 139 and 140 d, for ISA Brown maintained on 3 or 25 lux, but Shaver White pullets exposed to constant 3 lux matured significantly later than those maintained on 25 lux. 3. In Shaver Whites, sexual maturity was significantly delayed by an increase from 3 to 25 lux at 63 and 112 d, and advanced by a decrease from 25 to 3 lux at 112 d. Sexual maturity of ISA Browns was not significantly affected by a change in illuminance at 63 or 112 d, though responses were in the same direction as for Shaver Whites. 4. In both breeds, total feed consumed to 112 d was higher for birds on 3 lux than 25 lux, but lower between 112 d and 140 d when birds on 25 lux underwent rapid sexual development. In both breeds, body weight at 63 d was higher for birds exposed to 3 lux than 25 lux, but body weight gain thereafter was similar for the two light intensities. 5. In both breeds, plasma luteinising hormone (LH) concentration at 63 and 112 d was lower in birds maintained on 3 lux than 25 lux. At 63 and 112 d, transfers from 25 to 3 lux depressed, whereas transfers from 3 to 25 lux at 63 d, but not at 112 d, increased plasma LH. 6. Advances or delays in sexual maturity induced by changes in illuminance were not correlated with differences in feed intake, body weight gain, or with changes in plasma LH. 7. One possible explanation for the inverse relationship between the direction of change in illuminance at 63 and 112 d in pullets exposed to a 10-h photoperiod and the age at which they became sexually mature is that changes in light intensity and/or spectral composition affect the entrainment of the circadian rhythm of photoinducibility, to effect a phase shift in the photoinducible phase and/or the responsiveness of phototransduction pathways.

Effect of hens fed dietary flaxseed with and without a fatty liver supplement on hepatic, plasma and production characteristics relevant to fatty liver haemorrhagic syndrome in laying hens

1. Two long-term experiments were conducted with Single Comb White Leghorn (SCWL) hens (line UCD-003) predisposed to fatty liver haemorrhagic syndrome (FLHS). The first investigated the effect of adding a fatty liver supplement to the diet of laying hens prior to the onset of lay, and continuing either until peak production or throughout 39 weeks into lay. The second experiment, lasting 9 months into lay, investigated the effect of adding a fatty liver supplement, with or without 100 g/kg dietary ground flaxseed, to the diet. Body weight, feed intake, plasma triglycerides (in experiment 2) and egg production were measured throughout the experiment. Liver weight, liver fat content, liver malondialdehyde (MDA) content and liver haemorrhage score and fatty acid content of liver fat (in experiment 2) were measured at the end of each experiment. 2. In experiment 1, hens given diets containing the fatty liver supplement had higher egg production and eggshell strength, but there was no difference in liver parameters including MDA content or haemorrhage score compared with controls. 3. At the end of experiment 2, hens on 100 g/kg flaxseed diets had lower body weight, liver weight, liver dry matter and fat content, and plasma triglyceride concentrations than hens given the control diets. 4. Liver haemorrhage score was positively correlated with liver weight, but not with liver fat content, plasma triglyceride concentration or liver MDA content. This suggests that reducing the liver lipid content or feeding fatty liver supplements may not be as effective in controlling FLHS as controlling the size of the liver.

Long-term effects of feeding flaxseed on performance and egg fatty acid composition of brown and white hens

Two hundred fifty-six 18-wk-old Shaver White and ISA-Brown pullets were fed commercial diets containing either 0 or 10% flaxseed in order to study the long-term effects of feeding flaxseed on hen performance and egg production parameters. Performance was monitored over 10 consecutive 28-d periods. Flaxseed was introduced gradually at 28 wk of age and was maintained until hens were 53 wk of age, when flaxseed was gradually eliminated from the diet. Feed intake was less (P < 0.05) for hens fed flaxseed compared to those consuming the control diet. Flax-fed hens were also lighter (P < 0.05) compared to the control birds. Egg production, egg weight, shell weight, albumen height, and shell thickness were not significantly (P > 0.05) different for hens consuming 0 and 10% flaxseed; however, yolk weight was reduced (P < 0.05) in hens fed flaxseed. Both strains of birds fed flaxseed deposited significantly more n-3 fatty acids into their eggs. Sampling of livers at the end of the trial showed that hens fed flaxseed had a higher (P < 0.05) incidence of liver hemorrhages.

Quantitative and qualitative feed restriction on growth characteristics of male broiler chickens

Four experiments were conducted to evaluate the quantitative and qualitative feed restriction on the performance of male broiler chickens. In the first experiment, broilers fed identical pelleted diets were feed-restricted from 5 to 42 d by giving 95, 90, or 85% of the feed consumed ad libitum by control birds the previous day. In a second experiment, broilers were fed pellet or mash diets from 1 to 7 wk. In Experiments 3 and 4, broilers were feed-restricted to 90% of the ad libitum intake of a control group during different intervals. Results from Experiment 1 indicated that live body weight at 42 d was significantly different between unrestricted and restricted broilers (P < 0.01). A reduction in mortality was noted when feed intake was reduced (P < 0.05). In the second experiment, broilers fed mash had lower body weights and breast meat yields at 42 and 49 d (P < 0.05). Cumulative mortality at 42 and 49 d was reduced in broilers fed mash (P < 0.05). Results from Experiment 3 indicated that body weight and mortality were not significantly different (P > 0.05) at 42 d across treatments. There was a significant (P < 0.01) linear improvement on feed conversion at 42 d due to duration of feed restriction. Breast meat yield at 42 d was less in broilers subjected to mild feed restriction (P > 0.05) (Experiments 3 and 4). Broilers appeared able to recover from mild feed restriction, and there was always an associated reduction in mortality.

Alternatives for enrichment of eggs and chicken meat with omega-3 fatty acids

Interest on the enrichment of eggs and poultry meat with omega-3 fatty acids (n-3 FA) has increased given their important role in human metabolism. The inclusion of n-3 FA into eggs and poultry meat is achieved by feeding ingredients such as flaxseed, fish oil, fish meal, marine algae and canola to birds. However, problems in various production parameters and sensory quality of eggs and meat may arise. The former possibly caused by antinutritional and physiological effects and the latter influenced by the interaction of volatile substances. Possible increases in formulation costs also deserve attention.

Strategies to ameliorate these undesirable effects include limiting the inclusion levels of n-3 FA sources, time of feeding, mixing different n-3 FA sources in commercial rations, and including high levels of vitamin E along with high-quality ingredients. A mild heat treatment may eliminate some of the drawbacks of feeding flaxseed to birds. Key words: Omega-3, flaxseed, flax, menhaden oil, eggs, chicken meat

Developing a cancer genetics service in Wales: opinions of gynaecologists on the management of women at risk of familial ovarian cancer

In Wales, a cancer genetics service has been developing since 1998. Gynaecologists play an integral role in the management of women with a family history of ovarian cancer and we were interested in investigating referral practice and management for relatives of patients with ovarian cancer among gynaecologists in Wales. In 1999, a postal questionnaire was sent to all gynaecologists. The response rate was 51%. The questionnaire contained structured questions about current provision and a number of hypothetical scenarios to explore referral patterns to the cancer genetics service. The results of this study showed that referrals varied widely among specialists, as did the numbers who required onward referral to cancer genetics. The offer of screening to women at high risk of ovarian cancer was consistent, although there were variations in how often it was offered and the age at which it was offered. Most gynaecologists were easily able to establish when it was appropriate to refer onwards to cancer genetics, differentiating between women at high or low risk. There was some confusion about women at moderate risk of ovarian cancer. This study demonstrated the need for clear referral guidelines in Wales. Guidelines have since been distributed to all general practitioners and specialists; however, continued monitoring and further evaluation of referral practices will be necessary.

Lidocaine selectively blocks abnormal impulses arising from noninactivating Na channels

Abnormal, repetitive impulse firing arising from incomplete inactivation of Na+ channels may be involved in several diseases of muscle and nerve, including familial myotonias and neuropathic pain syndromes. Systemic local anesthetics have been shown to have clinical efficacy against myotonias and some forms of neuropathic pain, so we sought to develop an in vitro model to examine the cellular basis for these drugs' effects. In frog sciatic nerves, studied in vitro by the sucrose-gap method, peptide alpha-toxins from sea anemone (ATXII) or scorpion (LQIIa) venom, which inhibit Na+ channel inactivation, induced repetitively firing compound action potentials (CAPs) superimposed on a plateau depolarization lasting several seconds. The initial spike of the CAP was unaffected, but the plateau and repetitive firing were strongly suppressed by 5-30 microM lidocaine. Lidocaine caused a rapid, concentration-dependent decay of the plateau, quantitatively consistent with blockade of open Na(+) channels. Early and late repetitive firing were equally suppressed by lidocaine with IC50 = 10 microM. After washout of lidocaine and LQIIa, the plateau and repetitive firing remained for > 1 h, showing that lidocaine had not caused dissociation of channel-bound alpha-toxin. These findings indicate that therapeutic concentrations of lidocaine can reverse the "abnormal" features of action potentials caused by non-inactivating Na+ channels without affecting the normal spike component.

Performance of broilers fed limited quantities of feed or nutrients during seven to fourteen days of age

Three experiments were conducted with male broilers to study the effects of early life undernutrition. In all studies, treatments were represented by three or four replicate floor pens, each containing 30 to 40 birds. In Experiment 1, broilers were fed at 0.75 kcal ME/gBW0.67 for 4 d, 1.5 kcal ME/gBW0.67 for 5 d or 2.25 kcal ME/gBW0.67 for 6 d, all imposed beginning at 6 d of age. Birds were smaller following feed restriction (P < 0.01) although growth compensation occurred, and at 49 d all restricted birds were heavier (P < 0.01) than full-fed control birds. Improved growth was associated with improved feed conversion (P < 0.01), although carcass composition was unchanged. In a second study, birds were fed at 0.75 kcal ME/gBW0.67 for 3, 4, or 5 d, starting at either 4, 7, or 10 d of age. When feed restriction was applied early, or for shorter periods of time, growth compensation occurred (P > 0.05). With other more severe feed restriction, birds were smaller (P < 0.05) at 49 d compared to controls. Feed conversion was improved following prior feed restriction (P < 0.01, 0 to 49 d). In a third trial, broilers were fed a starter diet diluted with 50% oat hulls. Birds failed to consume enough of this diluted feed, and so were initially smaller. However 49-d weight was not affected (P > 0.05). When periods of 24-h feed withdrawal were imposed in conjunction with the diluted diets, birds were underweight at 49 d. It is concluded that physical feed restriction at 0.75 to 1.5 kcal ME/gBW0.67 imposed for 3 to 4 d in the second week of life currently presents the best option as a means of controlling broiler growth so as to improve feed efficiency.

Studies on the metabolizable energy content of ground full-fat flaxseed fed in mash, pellet, and crumbled diets assayed with birds of different ages

Four experiments were carried out to determine the AMEn of ground flaxseed in chickens of different ages and to study the effect of feeding flaxseed in pelleted or crumbled diets on flaxseed AMEn. A corn-soybean meal basal diet was prepared, in which the energy-yielding ingredients were substituted with ground flaxseed at 5, 10, 15, or 20%. Experiments 1, 2, and 3 consisted of these five dietary treatments replicated six times using 9-d-, 6-wk-, and 79-wk-old birds, respectively. A total collection procedure was used to measure diet AMEn, and linear regression analyses were used to calculate the AMEn value of flaxseed for birds at different ages. Experiment 4 involved birds fed either a basal or a 10% ground flaxseed diet prepared as mash, pellets, or crumbles. The flaxseed AMEn values obtained with 9-d- and 6-wk-old chickens were 2,118 and 2,055 kcal/kg, respectively. These values contrast with those of Experiments 3 and 4, in which mature roosters were fed mash diets with AMEn values of 3,560 and 3,654 kcal/kg, respectively. In Experiment 4, a significant improvement in flaxseed AMEn was observed when diets were pelleted or crumbled (4,578 and 4,277 kcal/kg, respectively). We concluded that the difference in AMEn of flaxseed observed in young birds vs. that found in mature birds was likely due to a greater tolerance of the latter to flaxseed, with less evidence of diarrhea. Feeding flaxseed in pellet or crumbled diets can significantly increase AMEn value.

Effect of feeding hens regular or deodorized menhaden oil on production parameters, yolk fatty acid profile, and sensory quality of eggs

An experiment was conducted to investigate whether feeding menhaden oil (MO) to hens affects egg weight, and whether using deodorized MO (DMO) could ameliorate decreased sensory quality of eggs (characteristic for hens fed high fish oil diets). Two-hundred twenty-four Single Comb White Leghorn hens were allocated to seven dietary treatments comprising either no fish oil, DMO, or regular MO (RMO) at 2, 4, and 6% in commercial-type diets from 19 to 55 wk of age. The data collected were analyzed in four experimental periods (i.e., 0, 2, 6, and 9 mo after feeding MO diets). The sensory evaluation of 2-wk stored eggs from hens fed the 2% RMO, 2% DMO, and control diets was undertaken. Egg weight decreased linearly with increasing MO in all periods tested (P < 0.05). The panelist's scores of aroma, taste, flavor, and acceptability of eggs from hens fed diets containing 2% of either RMO or DMO were lower (P < 0.05) than for control eggs. Greater aftertaste and off-flavors in these eggs were also detected. No differences in sensory quality (P > 0.05) for eggs from hens fed RMO vs. DMO were found. These results suggest that the deodorization of MO does not ameliorate the impaired sensory quality of eggs characteristic of hens fed MO.

Effects of menhaden oil and flaxseed in broiler diets on sensory quality and lipid composition of poultry meat

1. Three hundred and thirty 1-d-old male broiler chicks from a commercial strain were allocated to 11 dietary treatments comprising combinations of flaxseed at 100 g/kg and menhaden oil (MO) at 7.5 or 15 g/kg. Birds were given the experimental diets 7 or 14 d prior to slaughter. Carcase omega-3 fatty acid profiles and sensory evaluations of different cooked meat portions were carried out. 2. Linolenic acid was preferentially deposited in dark meat and long chain omega-3 fatty acids in white meat. Breast meat sensory quality was not affected in birds given 100 g/kg flaxseed for 14 d (treatment 3), 7.5 g/kg MO for 14 d (treatment 5) or 100 g/kg flaxseed +0.75 g/kg MO for 7 d (treatment 6). In contrast, thigh meat sensory quality decreased in treatments 5 and 6. 3. Feeding flaxseed and MO to birds for just 7 d prior to slaughter resulted in significant omega-3 meat enrichment depending on their dietary concentrations. The linolenic acid and long chain omega-3 fatty acids showed preferential deposition in dark and white meat, respectively, which may affect the sensory quality of various portions differently.

Effect of dietary flaxseed, flax oil and n-3 fatty acid supplement on hepatic and plasma characteristics relevant to fatty liver haemorrhagic syndrome in laying hens

1. Two experiments were carried out to investigate the effect of dietary flaxseed, flax oil and n-3 fatty acid supplementation (Dry n-3) on hepatic fat content, plasma triglycerides, hepatic haemorrhage score, egg production, food intake and body weight in an inbred line of Single Comb White Leghorns (UCD-003) predisposed to fatty liver haemorrhagic syndrome (FLHS) and normal SCWL hens. 2. Feeding diets containing 100 g/kg ground flaxseed, 40 g/kg flax oil, or 100 g/kg Dry n-3 reduced body weight and significantly reduced hepatic fat content compared to feeding the control diet with animal and vegetable oil as a fat source. 3. Hepatic malondialdehyde, an indicator of lipid peroxidation within the liver, was not significantly affected by dietary treatment. 4. Normal SCWL hens tended to have higher egg production, greater body weight, greater food intake and higher blood triglyceride concentrations than UCD-003 hens, although the strain effects were not significant. Liver weight as a percent of body weight was significantly lower in normal SCWL hens. Treatments by strain interactions were not found. 5. The result suggested that dietary flaxseed, flax oil and Dry n-3 decrease hepatic fat content and reduce body weight, 2 of the predisposing factors believed to contribute to FLHS onset. However, haemorrhages were still apparent in both strains regardless of treatment, indicating that other unknown underlying mechanisms may also be responsible for FLHS.

Efficacy of new bacterial phytase in poultry diets

Phytase produced by Escherichia coli was fed to broiler chicks fed graded levels of available phosphorus (0.25–45%). A positive control involved Natuphos® a fungal phytase commonly used in poultry nutrition. Feeding diets with only 0.25% available phosphorus from 1 to 13 d of age resulted in reduced feed intake and weight gain, with associated loss in tibia weight, tibia ash and tibia phosphorus content (P < 0.01). Adding 600 IU phytase kg−1 diet corrected these problems, and both sources were equally efficacious for most parameters studied. Key words: Phosphorus, phytase, chicken