Optimal in‐feed amino acid ratio for laying hens based on deletion method

A total of 56 Hy‐line W‐36 hens from 28 to 30 weeks were used on nitrogen balance (NB) trial to estimate daily N maintenance requirements (NMR) and the genetic potential for daily N retention (NR_maxT). The treatments consisted of six graded levels of nitrogen in the diets (N1 = 8; N2 = 16; N3 = 24; N4 = 32; N5 = 40; and N6 = 48 g N/kg of feed), formulated using the dilution technique. The regression analyses between nitrogen intake and excretion were performed to fit the exponential function and to determine the NMR = 292 mg/BW_kg^0.67, which was applied for further calculation of NR_maxT = 1,883 mg/BW_kg^0.67. A second NB trial was conducted, and a total of 96 Hy‐line W‐36 hens were used in the same period to estimate the ideal amino acid ratio (IAAR). Twelve treatments with eight replicates and one bird per cage were used. A balanced diet (BD) was formulated to meet the IAAR and the requirement of other nutrients for pullets. The limiting diets were formulated diluting BD with cornstarch and refilled with synthetic AAs and other feed ingredients, except for the AA under study. In each trial, the data of nitrogen intake, excretion, deposition and retention were obtained in a NB trial. The IAAR determined by Goettingen approach was Lys 100, Met+Cys 88, Trp 21, Thr 69, Arg 109, Val 90, Ile 75, Leu 127, Phe+Tir 110, Gly+Ser 73 and His 29%. The IAAR determined by Louvain approach was Lys 100, Met+Cys 88, Trp 21, Thr 69, Arg 104, Val 91, Ile 78, Leu 121, Phe+Tir 119, Gly+Ser 77 and His 29%.     

Effect of feeding guanidinoacetic acid and L‐arginine on the fertility rate and sperm penetration in the perivitelline layer of aged broiler breeder hens

Two experiments were conducted to evaluate the effects of feeding guanidinoacetic acid (GAA) and L‐arginine (ARG) on fertility and sperm penetration (SP) rate of broiler breeder hens. In the first experiment, a total of 200 broiler breeder hens (Ross 308) aged 53 week were randomly allotted to four dietary treatments (0, 0.6, 1.2 and 1.8 g GAA/kg diet) with five replicates of 10 birds each. In the second experiment, 320 broiler breeder hens (Ross 308) were used from 53 to 62 weeks of age in a 2 × 4 factorial arrangement (0 or 1.2 g GAA/kg diet along with 0, 3, 6 or 9 g ARG/kg diet). The hens received a diet containing 2800 kcal ME/kg and 14% CP. Sixteen sexually mature Ross 308 breeder roosters (34 weeks old) were used to artificially inseminate the hens. Fertility of the hens was determined in 61 and 62 weeks of age. The sperm penetration holes in the inner perivitelline layer (IPL) overlying the germinal disc were enumerated on days 3 and 7 following each insemination. Adding GAA to the breeder diet increased the number of SPs in the IPL and fertility in both experiments (p < 0.01). The interactive effect of ARG and GAA on the SP and fertility was significant. Supplementary ARG increased the SP rate in the IPL (p < 0.01). In conclusion, dietary supplementation of GAA and ARG might be potentially used to improve the fertility of broiler breeder hens at the later phase of the egg production period.     

Effect of dosage and application mode of l‐carnitine on plasma lipid and egg‐yolk cholesterol of turkeys,hatchability of eggs and post‐hatch growth of their offsprings

The effect of dosage and application mode of l ‐carnitine on plasma lipid and egg‐yolk cholesterol of breeder turkeys, hatchability of eggs and post‐hatch growth response was investigated using 180 breeder hens. The hens were assigned to six dietary treatments in a 2 × 3 factorial arrangements of two application modes of l ‐carnitine (diet and drinking water) supplemented at 0, 50 and 100 ppm (mg/kg or mg/l) levels, respectively. Each treatment was replicated five times with six hens per replicate. Dietary inclusion of 50 ppm l ‐carnitine showed the lowest (p < 0.01) plasma total cholesterol (TC) and low‐density lipoprotein concentration (LDL). Breeder hens offered 50 ppm l ‐carnitine with no regard to application mode recorded the highest (p < 0.01) plasma high‐density lipoprotein (HDL). Hens offered 50 and 100 ppm l ‐carnitine irrespective of application mode also showed reduced (p < 0.01) egg‐yolk TC concentration at 32 weeks of age. Dietary supplementation of 50 ppm l ‐carnitine for breeder turkeys recorded the lowest (p < 0.01) egg‐yolk triglyceride (TG) at 40 weeks of age. Hens offered 50 ppm l ‐carnitine irrespective of application mode recorded the highest (p < 0.05) hen‐day egg production. Incidence of dead‐in‐shell also reduced (p < 0.05) with increasing dosage of l ‐carnitine. Dietary supplementation of 50 ppm and oral application in drinking water of 100 ppm l ‐carnitine for breeder turkeys resulted in highest (p < 0.05) egg fertility. Offsprings from breeder hens fed diets supplemented with l ‐carnitine recorded no post‐hatch mortality. Highest (p < 0.05) post‐hatch final live weight and weight gain was obtained with poults obtained from hens fed diet supplemented with 50 ppm l ‐carnitine. In conclusion, dietary supplementation of 50 ppm l ‐carnitine for turkey hens showed improved serum lipid profile, egg fertility, reduced dead‐in‐shell, egg‐yolk cholesterol and resulted in improved post‐hatch growth performance.     

Effects of ad libitum feeding on performance of different strains of broiler breeders

(1) Tolerance to ad libitum feeding was compared in three genotypes of broiler breeder hens: a standard broiler breeder fed ad libitum (SA) or restricted (SR), a slow growing 'label' broiler breeder (L) and an experimental dwarf heavy broiler breeder (E). Two similar experiments were conducted in two distinct research centres. (2) Feed intake and body weight were measured every 3 weeks from hatch to 40 to 49 weeks of age. Egg production and egg abnormalities were recorded. The number of yellow follicles in ovaries was counted at the age of 32 weeks. (3) Body weight was stabilised at 2.2, 3.7 and 5.4 kg after 24 weeks of age in L, E and SA hens, respectively. Growth of the SR hens was similar to that of L up to 20 weeks and stabilised at a similar level to that of E hens after 30 weeks of age. (4) Sexual maturity was delayed by 6 weeks in restricted breeders compared to ad libitum fed hens that started to lay at 20 weeks. SA hens had low egg production and a high proportion of defective eggs, which was largely compensated for by feed restriction. However, productivity of SR hens remained lower than that of L breeders. (5) Compared to the low viability and reproductive fitness observed with SA hens, the E dwarf broiler breeder tolerated ad libitum feeding and had better egg production, fewer egg abnormalities and yellow follicles per ovary and a higher egg production. However, laying rate was still lower than that of the SR and L groups. Energy conversion (kJ/g egg) from 32 to 40 weeks of age was much higher in the SA group than in the other three groups. 6. The feasibility of feeding a dwarf broiler breeder ad libitum calls for further research on implications of specific IGF and GH-receptor expression at the level of the ovary in dw chickens.     

Eggshell conductance,embryonic growth,hatchability and embryonic mortality of broiler breeder eggs dipped into ascorbic acid solution

1. Eggs from a broiler breeder flock between 25 and 29 weeks of age were dipped into solutions of various concentrations of ascorbic acid (AA) for up to 2 min, in order to evaluate its effects on eggshell conductance (EC), amniotic fluid pH, albumen height and pH, embryonic weight and hatchability. 2. Three experiments were conducted and the following treatments were used: control, non-dipped (CND); control, water-dipped (CWD); 10 g AA/l (AA1); 20 g AA/l (AA2) and 30 g AA/l (AA3). Measurements of EC before and after dipping were made in experiments 1 and 2 in eggs from hens at 25 and 27 weeks of age, respectively. Albumen height and pH were measured after dipping the eggs in experiment 2. In experiment 3, egg weight loss, embryonic weight and amniotic fluid pH at 14 d of age, hatchability percentage (HP), and embryonic mortality were measured in eggs from hens at 29 weeks of age. 3. AA treatment of eggs and dipping period of time (1, 1.5 and 2 min) increased EC of eggs from hens at 25 and 27 weeks of age. 4. AA3 treatment for 2 min reduced albumen height and increased albumen pH of eggs when compared with the CND treatment in eggs from hens at 27 weeks of age. 5. HP of AA1-treated eggs from hens at 29 weeks of age was higher than that of the CND treatment. AA2 and AA3 treatments of eggs reduced HP and increased the percentage of non-pips when compared with any of the other treatments. 6. AA2 and AA3 treatments of eggs increased egg weight loss when compared with the control treatments (CND and CWD). Dipping treatment did not influence amniotic fluid pH or embryo weight expressed as a percentage of initial egg weight. 7. It is concluded that dipping hatching eggs into AA solution increased EC of eggs. Dipping eggs into 10 g AA/l for a period of 2 min increased HP in eggs from hens at 29 weeks of age, although this was not associated with a significant increase in egg weight loss.     

Dietary folate and vitamin B<Subscript>12</Subscript> supplementation and consequent vitamin deposition in chicken eggs

We determined the effects of dietary supplementation with folate and vitamin B₁₂ on lipid metabolism and the deposition of these vitamins in eggs of laying hens (age 64–72 weeks). Four levels of folate (0, 0.5, 4 and 10 mg/kg) and three levels of vitamin B₁₂ (0, 0.01 and 0.08 mg/kg) were added to the basal diet for 8 weeks in a 4 × 3 factorial completely randomized design study. No significant physiological interaction between folate and vitamin B₁₂ was evident under our experimental conditions. There was no effect of vitamins supplementation on egg production or feed intake. Supplementation with folate significantly elevated serum (p < 0.01) and yolk (p < 0.05) folate levels. Supplementation with vitamin B₁₂ did not significantly affect serum or egg yolk vitamin B₁₂ levels. Supplementation with folate or vitamin B₁₂ did not significantly affect triglyceride or total phospholipid levels in serum or egg yolk although a positive relationship was observed between dietary folate supplementation and total serum phospholipid (r ²  = 0.68, p < 0.05). The study showed that it is possible to produce folate-enriched eggs. An increase in serum total phospholipids due to dietary supplementation with folate may provide physiological benefits to hens, although we did not observe any strong effects of these vitamins on lipid composition.     

Comparative Study of Nitrogen Metabolism and the Nitrogen Maintenance Requirement in Lohmann Brown Roosters and Layers

The objective of this study was to investigate the effect of dietary protein level on nitrogen retention and compare nitrogen metabolism in Lohmann Brown adult roosters and layers. The nitrogen maintenance requirement (N_m) was determined based on the nitrogen balance. Thirty Lohmann Brown adult roosters and 30 laying hens at 27 weeks of age were randomly divided into five groups of six birds per group. The birds were fed with one of five diets containing 10.46%, 11.77%, 13.79%, 16.77% or 18.29% of crude protein. Nitrogen intake, nitrogen retention and nitrogen retention efficiency were higher in roosters than in laying hens, and the average nitrogen retention rate for groups fed with CP level of 11.77%, 13.79%, 16.77% and 18.29% was improved by 9.14%. The nitrogen maintenance requirement for Lohmann Brown roosters and laying hens at 27 weeks of age were 0.4245 g/d and 0.5059 g/d, respectively, and Nm based on average body weight (BW) and metabolic body weight (BW^0.75) was 0.2364 g/kg BW and 0.2739 g/kg BW^0.75 for laying hens and 0.2754 g/kg BW and 0.3208 g/kg BW^0.75 for roosters, respectively. The regression equations for daily N gain (N_B, protein accretion) vs. daily N intake (N_I) for Lohmann Brown layers and roosters were N_B = 0.3743N_I–0.1589 (R² = 0.79) and N_B = 0.6228N_I–0.3151 (R² = 0.85), respectively. The results of this study indicate that nitrogen intake and nitrogen retention at the same dietary CP level were higher in roosters than in laying hens.     

Effects of nanocalcium carbonate on egg production performance and plasma calcium of laying hens

This experiment was conducted to evaluate the effects of nanocalcium carbonate (NCC) instead of calcium carbonate (CC) on egg production, egg weight, egg mass, FCR, blood calcium and egg quality characteristics in laying hens. A total of 120 laying hens were used in a 10‐weeks trial, from week 23 to 33 of age. Laying hens were randomly assigned to six treatments with four replications, five hens each. The experimental treatments involved replacing 50% of the CC in the diet by decreasing amounts of NCC and were T1 Basal diet (BD) with 8.06% CC; T2 (6.045% of CC as a negative control); T3 (4.03% of CC replaced by 2.015% NCC); T4 (4.03% of CC replaced by 1.01% NCC); T5 (4.03% of CC replaced by 0.252% NCC) and T6 (4.03 of CC replaced with 0.126%NCC).Egg weight was unaffected by dietary treatments (p > .05). However, the egg production percentage and egg mass in T6 were less than that of other treatments (p < .05). The laying hens in the control group had the best average feed conversion ratio (p < .05). Also, the lowest concentration of calcium in hens’ blood was recorded for birds fed T6 (p < .05). The best egg shell quality (relative egg shell weight and egg shell weight/surface) was observed in T1 (p < .05).Collectively, our results demonstrated that NCC could replace CC at a lower inclusion level but extreme reduction of calcium concentration in diets (to 1.43% Ca in the T6 group) reduced production performance, egg quality characteristics, Tibia thickness and blood calcium of laying hens.     

标准回肠可消化氨基酸模式下降低饲粮粗蛋白质水平对蛋鸡生产性能、蛋品质及氮平衡的影响

本试验旨在研究标准回肠可消化(SID)氨基酸(AA)模式下,降低饲粮粗蛋白质(CP)水平对海兰灰蛋鸡生产性能、蛋品质及氮平衡的影响。选取540只20周龄体重相近且健康的海兰灰蛋鸡,随机分为5个处理,每个处理6个重复,每个重复18只鸡,预试期1周,正试期12周,采食等代谢能(11.82 MJ/kg)、等赖氨酸(Lys,SID Lys为0.831%)、相同AA模式、不同CP水平(18.0%、17.5%、17.0%、16.5%和16.0%)的试验饲粮。结果表明:SID AA模式下,降低饲粮CP水平可极显著降低平均蛋重和CP摄入量(P<0.01),显著降低鸡蛋浓蛋白高度(P<0.05),显著降低蛋鸡摄入氮和排出氮(P<0.05),有提高氮表观利用率的趋势(P=0.05);数据偏相关分析表明,饲粮中SID AA模式外的精氨酸、苯丙氨酸和亮氨酸水平下降与平均蛋重下降显著相关(P<0.05),与浓蛋白高度下降无显著相关(P>0.05)。结果提示,SID AA模式下,降低饲粮CP水平,除影响平均蛋重和浓蛋白高度外,对其他生产性能、蛋品质及血液生化指标影响较小,平均蛋重的下降与低CP饲粮中精氨酸、苯丙氨酸和亮氨酸不足有关;AA平衡的低CP饲粮,可在维持较高生产性能的同时减轻蛋鸡粪氮排出。     

Rare earth element‐enriched yeast improved egg production and egg quality in laying hens in the late period of peak egg production

The objective of this study was to determine the effects of rare earth element‐enriched yeast (RY) on egg production, coefficient of total tract apparent digestibility (CTTAD), egg quality, excreta gas emission and excreta microbiota of laying hens. A total of 216 ISA brown laying hens of 52 weeks of age were used in a 5‐week feeding trial and data were collected every week. Birds were randomly allotted to three dietary treatments each with six replicates and 12 hens per replicate. Each cage (38 cm width × 50 cm length × 40 cm height) contained one hen. Treatments consisted of corn–soya bean meal‐based diet supplemented with 0, 500 or 1000 mg/kg of RY. From weeks 55 to 56, inclusion of RY linearly increased (p < 0.05) egg production. The CTTAD of nitrogen was increased (linear, p < 0.05) with increasing dietary level of RY. In week 55, yolk height and Haugh units were increased linearly (p < 0.05) with increasing dietary RY content. However, no significant effects were observed in terms of excreta emissions and excreta microbiota in laying hens. In conclusion, dietary supplementation with RY improved egg production and CTTAD of nitrogen and slightly improved egg quality in laying hens of the late period of peak egg production.     

Feeding motivation on the incidence of floor eggs and extraneously calcified eggs laid by broiler breeder hens

1. Commercial broiler breeder hens lay many eggs on the floor rather than in nest boxes provided. A study was conducted to determine whether feeding feed-restricted broiler breeder hens during the sitting phase of nesting results in a higher incidence of floor eggs and/or retained eggs. 2. Sixty broiler breeder females (Ross 308) were randomly assigned to 6 deep litter pens containing 10 nest-boxes. At 35 weeks of age and for 9 weeks, feed was distributed to all pens at lights-on every second day (fed normally, FN). On alternate days (feeding delay, FD), feed was distributed when 2-3 hens/pen were sitting in a nest box. Behaviour was sampled at 41 weeks of age, for 26 d. Eggs and egg location data were collected daily, and eggs were scored for extra-cuticular calcium. 3. Of 81 instances in which the hen was sitting firmly in a nest box at the time of feeding, on 80 instances the hen left the nest-box to feed, and on one instance the hen laid her egg then exited to the feeder. Of these 80 instances, on 58 occasions the hen returned to a nest-box to lay her egg; on 12 the hen returned to the nest-box but laid no egg; on 7 the hen did not return to the nest box and laid no egg; and on three the hen laid her egg on the floor. 4. Mean floor egg percentage was 13·3 ± 3·2% on FN and 13·3 ± 4·7% on FD days; these did not differ significantly. 5. The mean extra-cuticular calcium score over all pens was 0·9 ± 0·06 on FN days and 1·2 ± 0·06 on FD days; these differed significantly. 6. In conclusion, feeding broiler breeder hens during nesting results in a conflict between feeding and nesting motivation and higher numbers of extraneously calcified eggs, but does not result in a significant increase in floor eggs even though nesting hens will leave the nest box for food.     

Effects of breeder hen age and dietary L-carnitine on progeny embryogenesis

1. Ross 308 broiler breeder hens were given diets containing 0 or 25 mg L-carnitine/kg (8 replications per treatment) from 21 weeks of age. 2. Hens were inseminated with semen from Ross broiler breeder males. In a common facility, subsequent progeny hatchability and embryonic mortality at 25, 30, 32, and 38 weeks of breeder age were evaluated. 3. Subsequent egg component weights, incubational egg water loss, progeny embryo growth, and embryo, yolk sac and liver composition through 18 d of incubation at 27, 32, and 38 weeks of breeder age were evaluated. 4. Calculated additions of L-carnitine were in agreement with analysed contents of 3.5 and 31.1 mg free L-carnitine/kg of diet, respectively, and total L-carnitine concentrations increased by 48.6, 21.7, and 10.0% in 0-d yolk, 18-d yolk sac, and 18-d liver samples, respectively, due to the addition of dietary L-carnitine. 5. Supplemental L-carnitine resulted in increased (0.6%) relative 0-d egg yolk weight across weeks 27, 32, and 38, and reduced (0.38%) 18-d yolk sac palmitoleic acid concentration at week 27 without altering embryogenesis. 6. In conclusion, dietary L-carnitine (25 mg/kg of the diet) was deposited in the yolks of broiler breeder hens and was subsequently transferred to the embryonic liver via yolk sac absorption through 18 d of incubation. Furthermore, dietary L-carnitine supplementation increased ovarian follicle yolk deposition in 27-, 32-, and 38-week-old breeder hens, and influenced yolk sac fatty acid beta-oxidation in embryos from 27-week-old breeder hens causing yolk sac palmitoleic acid concentrations to be reduced by 18 d of incubation.     

Effect of dietary manipulation and vaccination of turkey breeder hens on immunoglobulin levels of yolk,yolk sac and neonate poults

Two hundred turkey breeder hens and 24 viable toms of 30–35 weeks age of small white variety were distributed into two treatment groups having four replicates of 25 hens and three toms in each treatment. First four replicates were offered a turkey breeder diet (Diet A) (Nutrient requirements of poultry, 1994, National Academic Press, Washington, DC) and the rest four replicates were maintained on a higher plane of nutrition (Diet B) for 8‐week duration. After 6 weeks of experimental feeding, two replicates from each treatment groups were vaccinated with ND (R₂B) vaccine. Yolk sac of embryo from birds fed Diet B had a significantly higher (p < .05) IgG, IgM level and HI titre (log 2) than those fed Diet A. HI titre values of embryonic yolk sac from the vaccinated birds fed Diet B were significantly higher (p < .05) than that of the control groups. In addition, HI titre values were significantly higher (p < .05) in the day‐old poults of the birds fed Diet B than that of those fed Diet A. There was significantly (p < .01) positive correlation between serum IgG and IgM of the breeder birds and day‐old chicks. Similarly, there was significantly (p < .05) positive correlation between yolk IgG and IgM after 1‐month experimental feeding and yolk sac IgG and IgM. Positive correlation (p < .05) also existed between yolk sac IgM and day‐old chick serum IgM. Furthermore, the HI titres of breeder birds' serum at 14 days post‐vaccination were positively correlated with their egg yolk after 10 and 15 days post‐vaccination, yolk sac and day‐old chicks. Thus, the study envisaged that a higher immunity in neonate poults from turkey breeders maintained on a higher plane of nutrition may be elicited as there was maternal transfer of antibodies from the serum of breeder birds to their offsprings through their yolk sac.     

Changes in ovarian function and egg production in commercial broiler breeders through 40 weeks of lay

1. Egg production, body weight, feed intake and mortality were recorded in over 78?000 broiler breeder hens in 4 commercial flocks housed in 16 houses from early lay though 40 weeks of lay. A total of 420 hens were sampled at regular intervals throughout the laying period to determine the changes in body weight and the numbers of yellow follicles, paired follicles and hierarchical positions with time in the ovary throughout lay to relate ovarian function to productivity. Average egg weight was recorded weekly from one flock.

2. A quadratic equation fitted the changes in time for the number of yellow follicles, body weight, feed intake and mortality; a linear equation described the decline in the number positions in the hierarchy and there was a linear decline in the logistic scale of the proportions of yellow follicles developing as pairs of similar weight. Egg production was described by a cubic equation and egg weight by a line plus exponential model.

3. The average number of yellow follicles declined from 7·2 to 5·4 and the number of hierarchical positions from 6 to 5 from 4 to 40 weeks after photostimulation. The proportion of follicles developing as pairs of similar weight was over 25% at the onset of lay and declined to less than 10% from 20 weeks after photostimulation, representing a substantial loss of potential productivity.

4. Body weight and egg production were similar to the breeder's targets whereas average egg weight and mortality were higher than expected.

5. The relationship defining ovarian function will facilitate the development of an improved model of egg production in broiler breeder hens.     

Effect of sweet green pepper on yolk color and performance of laying hens

An experiment was conducted to evaluate the effects of sweet green pepper (SGP) on the performance and egg quality of commercial laying hens. A total of 144 Hy Line W36 egg layers were randomly assigned to 4 treatments with 9 replicate groups of 4 hens each. Treatments consisted of the following diets: 1) basal diet (BD), 2) BD + 75 ppm SGP, 3) BD + 125 ppm SGP, 4) BD + 225 ppm SGP. The diets contained 2,730 kcal/kg metabolizable energy and 15.5% crude protein. Egg production and egg quality were monitored for 16 weeks. Feed intake, hen-day egg production, egg mass, and feed conversion per dozen were not significantly affected by the addition of SGP to the diets. The addition of 225 ppm of SGP decreased egg weight. Specific gravity, albumen height, Haugh unit, yolk weight, albumen weight, albumen percentage, and yolk yellowness (b*) were not significantly affected by the addition of SGP. The addition of SGP to the diets increased yolk percentage, yolk color using a Roche fan, and yolk redness (a*). Based on these data, SGP was shown to be a useful feed ingredient for laying hens; it can be included in diets without negative effects on performance and egg quality. However, owing to the depression of egg weight with the inclusion of SGP, it may be of interest to producers and industry to control egg size in old layers and possibly improve shell quality. The addition of SGP to the diets impacted yolk color and may be useful in specialty markets.     

Modelling energy utilisation in broiler breeder hens

1. The objective of this study was to determine a metabolisable energy (ME) requirement model for broiler breeder hens. The influence of temperature on ME requirements for maintenance was determined in experiments conducted in three environmental rooms with temperatures kept constant at 13, 21 and 30 degrees C using a comparative slaughter technique. The energy requirements for weight gain were determined based upon body energy content and efficiency of energy utilisation for weight gain. The energy requirements for egg production were determined on the basis of egg energy content and efficiency of energy deposition in the eggs. 2. The following model was developed using these results: ME = kgW0.75(806.53-26.45T + 0.50T2) + 31.90G + 10.04EM, where kgW0.75 is body weight (kg) raised to the power 0.75, T is temperature ( degrees C), G is weight gain (g) and EM is egg mass (g). 3. A feeding trial was conducted using 400 Hubbard Hi-Yield broiler breeder hens and 40 Peterson males from 31 to 46 weeks of age in order to compare use of the model with a recommended feeding programme for this strain of bird. The application of the model in breeder hens provided good productive and reproductive performance and better results in feed and energy conversion than in hens fed according to strain recommendation. In conclusion, the model evaluated predicted an ME intake which matched breeder hens' requirements.     

The Impact of Yeast Culture Residue on the Suppression of Dietary Aflatoxin on the Performance of Broiler Breeder Hens

A study was conducted to examine the effect of yeast culture residue (YCR) on the suppression of aflatoxicosis in broiler breeder hens. One hundred twenty, 35-wk-old, Cobb broiler breeder hens of the same cross were fed diets supplemented with aflatoxin (AF) (0 or 3 mg/kg) and YCR (0 or 2 lb/ton) singly and combined in a 2 × 2 factorial designed experiment. The birds were randomly assigned to pens with 3 replicates of 10 females and 1 male per treatment. Eggs laid by the hens were collected daily, stored at room temperature, and incubated every 7 d for 3 wk. Response variables analyzed were mean percentage of fertility, hatchability, hen-day egg production, egg weight, chick weight at hatch, and embryonic mortality over the 3-wk treatment period. At the end of 3-wk treatment, blood was collected from the hens and analyzed for total protein, globulin, and albumin. Aflatoxin did not negatively affect fertility. However, hen-day egg production (57.6%), percentage of hatchability (67.6%), embryonic mortality (24%), serum total protein, globulin, and albumin were significantly (P < 0.05) affected by AF. Hatch of fertile eggs from the AF-fed hens was significantly lower than the control (67.6 vs. 78.5%). The inclusion of YCR in the AF-treated diet raised the level of hatchability (74.9 vs. 67.6%), egg production (65.83 vs. 57.26%), and lowered embryonic mortality (16.8 vs. 24%). Serum globulin and albumin were lowered in the AF-fed hens but was partially restored with the addition of YCR. The data demonstrated that YCR may enhance the performance of broiler breeder hens that are provided feed contaminated with AF.     

Selection with restriction in a poultry breeding scheme with different selection procedures in both sexes: Correlated responses

1. Mass selection in two replicate lines of Leghorn chickens was practiced for low 20‐week body weight in males and by an index designed to reduce age at first egg, body weight at 20 weeks and maintain a constant early egg size in females.

2. Selection responses in body weights of hens at 40 and 60 weeks of age, as well as in average egg weight of all eggs, egg number, egg mass and feed conversion at the above ages are given for 5 generations of selection.

3. Estimation of genetic responses were made separately for selection on males (M _i ) and females (F _i ) using control groups of hens from matings between females with an index near the population average and either males with body weight near the population average (Cl) or the selected males within lines (C2).

4. Total genetic response to selection of both parents (CR _i ) showed an expected decline in body weights of hens, small changes in egg weights and egg numbers, and an improved feed efficiency.     

Attempts to achieve low‐weight broiler breeder hens by severe growth depression during various periods up to 6 weeks of age and food allocation below the recommendations thereafter

1. Three experiments were carried out with White Rock (Anak) female chicks to evaluate the possibility of obtaining low‐weight breeder hens and to assess their reproduction potential. Such hens were obtained by early growth depression induced by either severe food restriction (SFR) from 1 or 2 to 3 or 4 weeks of age, or a low‐protein diet (LPD) fed from 0 to 6 weeks of age, or the use of diets containing 0·7 or 0·8% zinc as ZnO from 1 to 3 weeks of age, followed by food allocation below recommendation up to 22 or 67 weeks of age.

2. Body weights (BW) of the birds whose growth had been depressed were consistently and at time significantly lower than those of the control birds throughout the experiments. Age at first egg was delayed in hens previously fed the LPD and the diet containing the higher concentration of ZnO, and in those exposed to SFR from 2 to 4 weeks of age. BW at that time tended to be lower in birds whose growth had been depressed, although a significant effect was observed in only one experiment.

3. Egg production and egg size were not significantly affected by the various treatments, except for the lower production in hens fed the LPD at an early age.

4. Negative regressions (on an individual basis) were consistently observed between BW at 22 weeks of age and age at first egg, and between age at first egg and number of eggs laid. Positive regressions were observed between age at first egg and BW at that time. The regressions between BW at 22 weeks of age and number of eggs laid were positive but not always significant.

5. Severe growth depression at an early age (produced by food restriction or ZnO supplemented diet, but not LPD) followed by decreased allocation of food afterwards, could provide a means for reducing BW of broiler breeder hens without adversely affecting egg production. This procedure may save 2·5 to 6·6% of the food consumed during the life span of the birds.     

饲粮中添加植物精油对黄羽肉种鸡产蛋性能、蛋品质、孵化性能、生殖器官发育以及血浆和肝脏生化指标的影响

本试验旨在研究饲粮中添加植物精油对黄羽肉种鸡产蛋性能、蛋品质、孵化性能、生殖器官发育以及血浆和肝脏生化指标的影响。选择288只产蛋率和体重接近的45周龄岭南黄羽肉种母鸡,随机分为4个组,每组6个重复,每个重复12只鸡。对照组饲喂基础饲粮,试验组分别在基础饲粮中添加10、20、30 mg/kg植物精油。试验期10周。结果显示：1)饲粮中添加植物精油对黄羽肉种鸡的平均日产蛋重、料蛋比、平均蛋重、产蛋率、合格蛋率均无显著影响(P>0.05)。2)对照组的蛋白高度显著低于其他各组(P<0.05),对照组的哈氏单位显著低于10和20 mg/kg植物精油组(P<0.05),对照组的蛋壳厚度显著低于20 mg/kg植物精油组(P<0.05)。3)对照组的受精蛋孵化率显著低于10 mg/kg植物精油组(P<0.05)。4)对照组的卵巢系数显著低于10和20 mg/kg植物精油组(P<0.05),对照组的输卵管重量和输卵管系数显著低于10 mg/kg植物精油组(P<0.05)。5)对照组的血浆低密度脂蛋白胆固醇含量显著高于20 mg/kg植物精油组(P<0...