Hy-Line W36 Hens Research Articles

Intestinal Calcium Uptake, Shell Quality and Reproductive Hormones Levels of Three Laying Hen Varieties after Prolonged Egg Production

Hy-Line W98, W36, and Brown hens are among the most popular strains for commercial egg production. It is of interest to evaluate the differences in performance of old hens of each variety. As part of a larger study, hens of the three varieties were maintained under production longer than 100 weeks of age and hens of each strain were randomly selected for in vitro calcium uptake (CaT) by duodenal cells. Blood samples were collected 4-6 hours prior to oviposition via brachial vein cannulation for plasma estrogen (E ), 2 Luteinizing hormone (LH), and progesterone (P ) determination. Hens were then euthanatized by cervical 4 dislocation and CaT determined. The data were analyzed as a completely randomized design, using the General Linear Model procedure (SAS, Proc GLM, 2001), with strain as a fixed treatment and hen as the experimental unit nested with strain. For W36 hens, CaT was significantly greater than that found in Brown hens (P=0.05) while for W98 did not differ from W36 and Brown strains. P , E and LH concentrations were 4 2 not significantly different in the three varieties of laying hens. Based on the higher CaT by duodenal cells, these results suggest a higher efficiency of the W36 hens in calcium regulation during the terminal phase of egg production (more than 100 weeks of age) compared to the Brown and W98 hens. However, when specific gravity and thickness of shells were compared, the W36 appeared to have no advantage over W98 (P=0.460 and 0.684) or Brown (P=0.197 and 0.941) hens, respectively.

Effect of Reducing Cage Density on Performance and Economics of Second-Cycle (Force Rested) Commercial Leghorns

In 2002 the United Egg Producers announced a new certification program that requires a significant increase in space per hen to produce eggs meeting animal welfare guidelines. Because there is little information concerning the influence of space per hen on hen performance of modern strains and increased cost associated with reduced hen numbers, this study was conducted to determine the effect of increasing space per hen on hen performance and economic returns. HyLine W36 hens (n = 1,120) were force rested at 68 wk of age and were kept in an environmentally controlled house at 3 or 4 per cage (64 or 48 in. 2/hen). After force resting, hens were fed a commercial layer corn-soy diet containing 0.92% lysine and 1,283 kcal ME/lb (2,823 kcal ME/kg) feed for 14 wk. Average house temperature was maintained at 78°F (25.6°C), and hens were provided a 16L:8D photoperiod. Increasing space per hen increased 14-wk average feed intake (85.7 to 89.6 g; P < 0.001), egg production (73 to 75%; P < 0.05), and egg weight (61.7 to 62.4g; P < 0.05) but had no effect on egg specific gravity or mortality. Increasing space per hen improved overall feed efficiency from 3.17 to 3.11 lb (1.44 to 1.41 kg) of feed per dozen eggs (P < 0.05) and improved egg mass from 45.0 to 47.0 g/h per day (P < 0.01). Economic analysis of increasing space per hen indicated an increase in return (egg price minus feed cost) with the increase dependent upon the price spread between large, extra-large, and jumbo eggs. The significant improvement in feed efficiency would help offset some of the cost involved in increasing space per hen (hen numbers) during summer months. Results could be different for larger strains and under different environmental conditions.

The effect of corn oil reduction in the diet on laying hen performance

Hy-Line W36 hens were fed diets containing zero or 6% corn oil (CO) from 26 to 38 wk of age. At 38 wk, the hens receiving the diet with 6% CO were divided into three groups. One group continued to receive the diet with 6% CO. The level of CO in the diet was reduced to zero or 3% in the other two groups. The hens previously fed the diet without CO continued to receive the control diet. Egg weight was significantly heavier when the diet contained 6% CO and was not significantly reduced when the level of CO was reduced to 3%. Egg weight from control hens was significantly lower than the EW from hens that had received CO in the diet until 38 wk but none thereafter. Hens fed the diet with CO consumed more energy than hens fed the control diet. However, when CO level was reduced to zero at 38 wk, the hens consumed less energy than hens fed the control diet. These findings indicate that the hen cannot adjust feed intake with diets based on changing energy concentration in the range from 2,783 to 3,089 kcal/kg.

Exogenous Estrogen Boosts Circulating Estradiol Concentrations and Calcium Uptake by Duodenal Tissue in Heat-Stressed Hens

In the hen, heat stress (HS) disrupts shell calcification and reproductive processes, including hormone synthesis and egg production. Two studies were conducted to investigate palliative effects of exogenous estrogen or dietary vitamin D3 on Ca homeostasis and reproductive physiology during HS. Study 1: Hy-Line W36 hens were randomly assigned to thermoneutral (TN) or HS treatments and to 1 of 7 estrogen treatments: zero (control) or one Compudose 200 implant given 1, 2, 3, 8, 9, or 10 d before onset of HS. With no implant, HS reduced plasma estradiol (E2) and total Ca absorbed (CaT) by duodenal cells (P < 0.05). In TN hens with implants, plasma E2 tripled within 24 h (P < 0.05) and remained elevated (P < 0.05) through d 9. In HS hens with implants, plasma E2 rose 6-fold (P < 0.05) to equal TN+E2 concentrations and remained elevated through d 10. In TN and HS hens with implants, the rate of Ca absorption (CaTR) and CaT increased dramatically; the responses were quadratic and essentially identical. Study 2: Hy-Line W36 hens were provided diets formulated either according to NRC requirements (NRC, 1994), or with the addition of 22,000 IU/kg vitamin D3 (+VD hens). A 24-h HS episode was imposed 2 wk after initiation of the dietary regimen. Duodenal samples were collected for Ca absorption assays after the 24-h HS episode. Both CaTR and CaT in +VD hens were approximately 3-fold higher than in hens in the NVD group (P = 0.102). The results lead to the conclusion that exogenous estrogen, high levels of dietary vitamin D, or both, before a HS episode, are efficacious in alleviating at least some of the effects of HS and should be further investigated.

Influence of Adding Synthetic Lysine in Corn-Soy Diets for Commercial Leghorns

An experiment was conducted as a 2 x 5 factorial to determine if increasing dietary lysine in corn- soy diets formulated based on lysine improves egg weight (EW) and egg production (EP) in commercia l Leghorns. A set of five corn-soy diets with similar levels of energy were formulated based on lysine to contain 0.97, 0.92, 0.87, 0.83 and 0.79% lysine. These diets contained no synthetic lysine. A second set of five diets were formulated by supplementing 0.097% synthetic lysine to each diet in the first set. Hy-Line W36 hens (n=1,280; 21 wk of age) were randomly assigned in replicates of 16 hens to the ten dietary treatments for 16 weeks. Feed consumption (FC), EP, EW and egg specific gravity (ESG) were measured. Adding synthetic lysine to diets formulated based on lysine had no significant effect on EP, EW, ESG or FC of hens. Also, amino acid density had no effect (P > 0.05) on EP, FC, or ESG. However, EW linearly increased (P < 0.01) as amino acid density increased. These results indicate that adding 0.097% additional synthetic lysine to corn-soy diets formulated based on lysine containing 0.79 to 0.97% lysine had no significant influence on performance of commercial Leghorns.

Influence of Calsporin on Commercial Leghorns

A study was conducted to determine if Calsporin (Bacillus subtilis C-3102), a direct-fed microbial (probiotic), improved performance of commercial Leghorns and eggshell quality. Hyline W36 hens (n = 1,440; age = 65 wk) in 90 groups (16 hens/group) were randomly allocated to three dietary protein levels (17.3, 16.1, and 15.0%), and three Calsporin levels (0.0, 0.003 and 0.006%) in a 3 × 3 factorial for 10 wk. A Calsporin × protein interaction was observed on egg specific gravity (SG; P < 0.01). Egg SG increased more in hens fed the higher Calsporin level than in hens fed the lower level when dietary protein was 15%. This Calsporin level effect was reversed as dietary protein was increased to 16.1%. Trends similar to that of SG were also observed on eggshell thickness. Increasing dietary protein had a beneficial effect (P < 0.001) on egg production, feed consumption, and egg weight. Addition of Calsporin to hen diets had no significant influence on feed consumption, egg production, egg weight, or body weight of hens. More research is required to optimize any potential benefit of Calsporin with respect to dietary protein on eggshell quality.

Re-evaluation of the isoleucine requirement of the commercial layer

An experiment was conducted with Hy-Line W36 hens to re-evaluate their Ile requirements from a corn-soybean meal diet. Eight experimental diets were fed with Ile levels of 0.60, 0.57, 0.54, 0.51, 0.48, 0.45, 0.42, and 0.39%. Supplemental amino acids (AA) were added to ensure that ILe was the first-limiting AA. Increasing levels of Ile above 0.51% significantly increased egg production (EP), egg weight (EW), and egg mass (EM). Egg production, EW, and EM decreased each time the Ile content of the diet was decreased. Feed consumption (FC) and energy intake were not significantly decreased until the diet contained 0.45% Ile, and, at this time, BW was significantly reduced. Broken-line regression indicated a daily Ile requirement of 449.8, 497.0, and 469.0 mg/d for EP, EW, and EM, respectively, which indicated a requirement of 9.30 mg Ile/g EM.

The enrichment of eggs with folic acid through supplementation of the laying hen diet

In light of evidence supporting a need for humans to increase their dietary folate intakes, experiments were conducted to evaluate the extent to which egg folate levels could be increased. In Study 1, Hyline W36 hens (n = 6/diet) received a barley-based diet, containing 0 or 10 mg/kg of crystalline folic acid, to establish the potential for folate incorporation into table eggs. In Study 2, 70 hens were divided into seven treatment groups (n = 10 hens/diet) and received diets supplemented with 0, 1, 2, 4, 8, 16, or 32 mg folic acid/kg diet. In Study 3, 64 hens received the barley-based diet with or without 4 mg folic acid/kg diet. Eggs were collected and stored for 0, 7, 14, 21, or 28 d, prior to folate determinations. The folate content of eggs was determined by HPLC for 5-methyltetrahydrofolate (the sole form of folate in egg yolk). Results from Study 1 showed that a 10 mg/kg inclusion of folic acid increased folate incorporation into egg yolk (41.0 +/− 0.7 microg /egg) over that of an unsupplemented diet (17.5 +/− 0.7 microg /egg; P = 0.0001). In Study 2, the response of egg folate to dietary folic acid supplementation was saturable, with 90% of maximal egg folate levels established at approximately 4 mg folic acid/ kg diet. Results from Study 3 showed that folate levels are stable, in control and fortified eggs, during 28 d of storage at 4 C. In terms of its nutritional value, one large egg collected from a folic acid-supplemented hen provided approximately 12.5% of the recommended dietary allowance (RDA) for adult humans (RDA = 400 mg/d).

Threonine requirement of commercial laying hens fed a corn-soybean meal diet

Two experiments were conducted with Hy-Line W36 hens to evaluate their Thr requirement in a corn-soybean meal diet. Eight experimental diets were used in Experiment 1 with graded levels of Thr: 0.53,0.50, 0.48, 0.45, 0.42, 0.40, 0.37, and 0.35%. Seven experimental diets were used in Experiment 2 with graded levels of Thr: 0.58, 0.53, 0.50, 0.48, 0.45, 0.42, and 0.40%. Supplemental amino acids (AA) were added to all diets to ensure that Thr was the first-limiting AA. Egg production (EP), egg mass (EM), and daily Thr intake were significantly increased with increasing dietary Thr levels. Broken-line regression indicated a daily Thr requirement of 439.0 and 462.1 mg per hen per d in Experiment 1 and of 393.9 and 447.1 mg per hen per d in Experiment 2 for EP and EM, respectively. The Thr requirements to produce 1 g of EM were 8.76 and 9.44 mg in Experiments 1 and 2, respectively.

Influence of Dietary Phosphorus on Performance of Hy-Line W36 Hens

Two experiments were conducted to determine the effect of nonphytate phosphorus (NPP) on hen performance in an environmentally controlled house. In Experiment 1, 21-wk-old Hy-Line W36 hens (n = 1,248) were randomly assigned to 13 dietary treatments (0.1 to 0.7% NPP, at graded increments of 0.05%) for 17 wk. In Experiment 2, 45-wk-old Hy-Line W36 hens (n = 960) were randomly allocated to eight diets in a 2 × 4 factorial arrangement of treatments. Two levels of Ca (3 and 4%) and four levels of NPP (0.1, 0.2, 0.3, and 0.4%) were fed for 8 wk. Feed consumption (FC), egg production (EP), egg weight (EW), egg specific gravity (ESG), bone density (BD), bone mineral content (BMC), bone breaking strength (BBS), BW and mortality were evaluated to determine performance. Results of Experiment 1 indicated that FC, EP, and BW increased as NPP was increased from 0.1 to 0.7% (77 to 588 mg/hen/d). During Week 12, a sharp decrease in FC and EP was observed in hens fed the most deficient level of 0.1% NPP. Egg weight and ESG decreased linearly (P < 0.05) as dietary NPP was increased from 0.1 to 0.7%. However, after 14 wk, ESG decreased (P < 0.05) in hens fed 0.1% NPP. Bone breaking strength was higher (P < 0.05) in hens fed 0.3 to 0.4% NPP, indicating maximum bone quality. Mortality was higher (P < 0.05) in hens fed 0.01% NPP, followed by hens fed 0.15% NPP. In Experiment 2, a pronounced adverse effect of P deficiency was observed on FC and EP within 2 wk compared with 12 wk in Experiment 1. Reduction of NPP to 0.1% reduced BD, BMC, BBS and increased hen mortality (P < 0.05). Reducing dietary Ca from 4 to 3% decreased ESG (P < 0.05). A wide variation in response time to P deficiency indicated that P requirement varied for different performance criteria with age.

Performance of Four Strains of Commercial Layers With Major Changes in Dietary Energy

An experiment was conducted to determine how four strains of commercial laying hens would respond to an increase or decrease in dietary energy. Forty of each of Hy-Line Brown, Hy-Line W98, Hy-Line W36, and DeKalb White hens were fed each of three diets from 36 to 44 weeks of age. The energy contents of these diets were 2,519 (low), 2,798 (control) and 3,078 (high) kcal ME/kg. The energy of low and high diets was 10% less and 10% more than the control diets, respectively. Hens fed the low energy diet consumed 8.5% more feed than did hens fed the control diet, and hens fed the high energy diet consumed 1.5% less feed than did hens fed the control diet, which indicated that the hens were more sensitive to lowering the energy than increasing energy in the diet. The Hy-Line W98 and the Hy-Line Brown were more sensitive to the change in energy than the Hy-Line W36 and DeKalb White. Egg production (EP) was not affected by dietary energy level. The high energy diet (containing 5.963% corn oil) significantly increased egg weight (EW). This diet may be beneficial for improving early EW.

Energy Utilization of Four Strains of Commercial Layers and Influence on Suggested Dietary Methionine Level

Harms, R.H., Russell, G.B. and Sloan, D.R. 2000. Energy utilization of four strains of commercial layers and influence on suggested dietary methionine level. J. Appl. Anim. Res., 18: 25–31. An experiment was conducted to compare the energy required to produce a g of egg content (EC) for four strains of commercial layers. Calculations were made to demonstrate the effect on the level of Met needed in the diet. The energy required to produce a g of EC was 6.60, 5.78, 6.09 and 6.35 kcal, respectively for the Hy-Line Brown, Hy-Line W36, Hy-Line W98 and DeKalb White hens. Therefore, the calculated requirement for percent of Met needed in the feed in this experiment (2799 kcal/kg) would be 0.254, 0.312, 0.276, and 0.260%, respectively for Hy-Line Brown, Hy-Line W36, Hy-Line 98 and DeKalb White.

Evaluation of the Isoleucine Requirement of the Commercial Layer in a Corn-Soybean Meal Diet

An experiment was conducted with Hy-Line W36 hens to evaluate their Ile requirement in a corn-soybean meal diet. Five experimental diets were fed with Ile levels of 0.61, 0.58, 0.55, 0.52, and 0.49%. Supplemental amino acids (AA) were added to ensure that Ile was the first-limiting AA. Two diets with 0.55 and 0.52% Ile were also fed with higher levels of supplemental AA. A positive control (0.67% Ile) with only Met supplementation was fed, which had previously been shown to support maximum performance. All levels of Ile addition significantly increased egg production (EP), egg weight (EW), and egg contents (EC).Broken-line regression indicated a daily Ile requirement of 589.2, 601.2, and 601.4 mg per day for EP, EW, and EC, respectively, which indicated a requirement of 12.6 mg Ile per gram of EC.

Evaluation of tryptophan requirement of the commercial layer by using a corn-soybean meal basal diet

An experiment was conduced with Hy-Line W36 hens to evaluate the requirement for Trp in a corn-soybean meal diet. Seven experimental diets were fed with Trp levels of 0.12, 0.13, 0.14, 0.15, 0.16, 0.17 and 0.18%. Supplemental amino acids (AA) were added to all diets to ensure that Trp was the first-limiting AA. A positive control diet (0.20% Trp) with Met supplementation was fed that had previously been shown to support maximum performance. Egg production (EP), egg weight (EW), and egg content (EC) were significantly increased by the addition of Trp to the basal diet. Broken-line regression indicated the Trp requirement for EP and EC was 139.8 and 149.0 mg per hen/d, respectively, for EP and EC when hens had a daily EC of 45.4 g per hen/d.

Laying hen behavior. 1. Effects of cage type and startle stimuli

The well-being of commercial laying hens plays an important role in egg production. Behaviors such as pacing, displaced preening, increased aggression, and redirected activities have been associated with stress in poultry. This study was conducted to determine whether two strains of commercial layers, reported to differ in level of excitability, behave differently in two types of commercial cages. DeKalb Delta and Hy-Line W36 hens, 40 to 45 wk of age, were housed six to eight per cage in open or solid-sided cages, at an equal density between cages. For each strain, there were six cages per cage type for a total of 24 cages. In the first five experiments, behavioral data were obtained at a distance of 1 m by instantaneous or scan sampling. These experiments included hen behavior in both types of cages with and without the presence of frustrating or startle conditions. Some significant differences in behavior existed within experiments but not consistently among all experiments. Sampling method did not affect reliability of data collection. Two trials were then conducted to determine whether the length of time to return to normal activity after a startle stimulus is influenced by the cage type or strain. In the first startle experiment, DeKalb hens returned to normal activity more quickly than did Hy-Line hens (P = 0.07); this strain difference was not found when the experiment was repeated. Cage type did not appear to affect the behavior of birds adversely, although neither cage type appeared to confer an advantage. No clear differences were found in behavior by strain or by strain within cage.

Laying hen behavior 2. Cage type preference and heterophil to lymphocyte ratios

Studies were conducted to determine hen preference for and stress response to cage type. By using a plywood (1.25 cm) test apparatus with open- and solid-sided compartments and a plexiglass divider at the entrance for controlling passage, birds (n = 20) were evaluated as to their choice of compartment after training and acclimation. For each test, after training, an individual bird was placed in the start box and given 1 min to acclimate before making a choice. The experiment was repeated after rotating the apparatus 180 degrees. In Experiment 1, the open-sided compartment was chosen by 45% of the hens, and the solid-sided compartment by 25% (P = 0.02); 30% chose neither. In Experiment 2, the compartment with open sides was chosen by 70% of the hens, and that with solid sides was chosen by 15% (P = 0.004); 15% chose neither. The length of time required to choose one compartment over the other did not differ in either experiment (P = 0.29; P = 0.76). In Experiment 3, tests were videotaped from 0830 h to 1330 h, and tapes were scored for time spent in each compartment. Birds were observed to spend more time in open- compared with solid-sided compartments (P = 0.02). To assess stress level of birds exposed to each type of enclosure, blood was collected from 24 commercial Hy-Line W36 hens housed long-term in either open (n = 12) or solid (n = 12) cages, and heterophil:lymphocyte (H:L) ratios were determined. Birds in solid cages had higher H:L ratios than did birds in open cages (P = 0.02), indicating a greater stress response. These data would suggest that hens may prefer greater visual access to their surroundings afforded by open cages.

Changes in Bone Fragility in Laying Hens

An experiment was conducted with Hy-Line W36 hens to determine the influence of age on tibia ash and breaking strength of hens kept in cages and floor pens. Breaking strength progressively decreased from 20 to 32 weeks of age for hens kept in cages and floor pens. However, the decrease was greater with hens kept in cages. Tibia ash progressively increased from 20 to 32 weeks of age; there was no difference after 23 weeks of age between cage and floor groups.Twenty hens were moved from cages to floor and 20 were moved from the floor to cages at 26 weeks of age. Tibia breaking strength did not significantly change for those moved from cages to floor and decreased for those moved from floor to cages. The difference between the two groups was not statistically significant at 32 weeks of age.