Hen-day Egg Production Research Articles

Effect of Graded Replacement of Soybean Meal by Faba Beans (Vicia faba L.) or Field Peas (Pisum sativum L.) in Rations for Laying Hens on Egg Production and Quality

Two separate randomised block design experiments were each carried out for 13 months to investigate the effects of replacing, in-part, soybean meal (SBM) and wheat by graded levels of faba beans (FB) and field pea (FP) in a basal diet of wheat-SBM, balanced for amino acids, similar in crude protein (CP) and metabolisable energy (ME) on Lohmann hens. Traits studied included ; egg production, feed consumption, body weight gain, feed, energy and protein utilisations, and egg quality. Increasing dietary FB up 400g/kg (no SBM) decreased hen-day egg production, from 85 to 75%. Average egg mass significantly reduced from 50.8-43.5g/(hen*d). Feed consumption was similar (110 to 113g/(hen*d)). Increasing FB increased ME and CP required for egg production. FB had no significant effect on the shell strength, shell fraction and yolk index of eggs ; meanwhile it decreased the yolk fraction, and increased yolk colour, albumen fraction and albumen index. Most traits studied, were statistically similar up to 160g FB/kg feed. Increasing levels of FP up to 500g/kg did not significantly affect hen-day egg production and egg mass per day, although feed consumption increased. Body weight gain linearly dropped with increasing FP. FP had no significant effect on any of the egg quality traits studied. 16% FB and 50% FP could be included in layers diet without any significant effects on egg production or quality.

The effect of long-term feeding of conjugated linoleic acid on fertility in Japanese quail

The objective of this study was to determine the effects of the long-term feeding of conjugated linoleic acid (CLA) on laying hen performance, egg fertility and hatchability of fertile eggs of Japanese quail (Coturnix coturnix japonica). One hundred and sixty 7-day old Japanese quail chicks were randomly assigned to four groups (40 birds per group) and fed for five weeks on a commercial diet supplemented with either 0.5% hazelnut (Group A), 0.5% sunflower oil (Group B), 0.25% CLA (Group C) or 0.5% CLA (Group D). The birds received water and feed ad libitum during the study. At the end of the five weeks the birds were sexed, and 21 females and seven males from each group were selected. For a further six weeks these selected birds were fed a layer diet supplemented with their respective sources of oil. Eggs were collected daily and incubated weekly. The fertility rate was determined by visual inspection at the end of the incubation period. Dietary CLA at the inclusion level of 0.5%, but not at 0.25%, caused a significant decrease in percentage hatchability of the fertile eggs compared to Groups A and B. Hatchability of fertile eggs from Groups A, B, C and D was 74, 80, 72 and 70, respectively. Fertility rates between Groups A, B, C and D did not differ significantly, and were 64.4, 56.4, 66.0 and 62.8%, respectively. Hen-day egg production of Groups A, C and D were similar, but in weeks 3, 4, 5 and 6, hens in Group B had a significantly lower hen-day egg production (%) compared to Group A. Also, in weeks 3, 4, 5 and 6, egg size in Group B was significantly lower than that in the other groups. From this study it is concluded that dietary CLA at inclusion levels of 0.25% or 0.5% did not influence egg fertility, egg weight and egg production in Japanese quail. South African Journal of Animal Science Vol. 36(2) 2006: 99-104

Laying Performance of Pearl Gray Guinea Fowl Hens as Affected by Caging Density

The caging density required for optimal egg production by various avian species and varieties is highly variable. Even so, little is known of the required cage density for optimum performance of the laying guinea fowl (Numida meleagris). The objective of this study was to assess the effect of varying cage densities on production performance of pearl gray guinea fowl laying hens. In 3 replicates, 270 pearl gray guinea hens [28 wk of age (WOA)] were weighed individually and randomly assigned to laying cages at densities of 1, 2, and 3 birds/cage, equivalent to 1,394, 697, and 465 cm2/bird, respectively. During the experiment, all birds received a 16-h lighting regimen and were fed the same diet, comprising 2,800 kcal of ME/kg of diet and 16% CP (28 to 59 WOA) and 2,800 kcal of ME/kg of diet and 14% CP (60 to 76 WOA). Feed and water were provided for ad libitum consumption. Experimental birds were observed for feed consumption (FC), hen-day egg production (HDEP), egg weight, egg mass (EM), feed conversion ratio, internal egg quality, and shell thickness at the end of each 28-d lay period for 11 consecutive periods. Mean FC and HDEP decreased significantly with increases in cage density, such that 1,394 > 697 > 465 cm2/bird. Mean EM was also higher (P < 0.05) for birds reared in cages at 1,394 cm2/bird than those reared in cages at 697 and 465 cm2/bird (24.8, 17.4, and 14 g/hen per d, respectively). Feed conversion, HDEP, and EM were negatively correlated with cage density (P < 0.05). Mean feed conversion ratio and percentage of mortality were also lower in birds reared in cages at 1,394 cm2/bird than in other treatment groups. Therefore, laying guinea fowl hens exhibited superior performance when raised at a density of 1 bird/cage (1,394 cm2/bird) than those reared at densities of 2 and 3 birds/cage (697 and 465 cm2/bird, respectively).

Building Environment and Interaction of Population Density and Position and Their Relationship to Layer Performance

In this study it was aimed to determine the effects of hen age, cage position and cage density on egg production and quality characteristics in laying hens. One thousand and thirty six 25 wk old Isa Brown layers, at the beginning of laying period, were used in experiment. Two cage bateries which were parallel to the long axis were selected as the study material. Cage densities were four, and five birds per cage, respectively. Different egg production and egg quality parameters were measured for different hen age, cage position and densities for 11 weeks. Egg samples were collected from the cages to define the egg quality characteristics once a week. Indoor environmental conditions such as temperature and humidity were fairly affected by cage density (P<0.01). However, they did not differ among cage positions. Hen age had a significant effect on hen-day egg production (HDEP), feed consumption (FCS), feed conversion (FCV), and egg quality characteristics (P<0.01). The weekly observations showed that cage position and cage density did not have major influence on HDEP, FCS and FCV. On the other hand, HDEP and FCS were higher for four birds per cage on the window side. No egg quality characteristics were impacted by cage position and cage density. Differences between hen age for mortality were significant (P<0.01). Even though the cage position effect on mortality was not significant, the highest mortality was observed on corridor side. The mortalities were differed (P<0.05) among cage densities. Mortality in lower cage density was less than higher cage density. The study concluded that the interactions among hen age, cage position and cage density were significant for some variables.

Physiological and Antioxidative Effects of Dietary Acetyl Salicylic Acid in Laying Japanese Quail (Coturnix japonica) under High Ambient Temperature

The objective of the present study was to determine if acetylsalicylic acid (ASA) would have further antioxidative effects beyond lowering rectal temperature of stressed laying Japanese quail and hence improve its physiological status. During summer season when daily high temperatures averaged between 33 and 36°C and relative humidity averaged between 60 to 70%, four treatment groups of adult Japanese quail each containing three replicates of fifteen females were fed either a control diet containing 0% ASA or the control diet supplemented with 0.025, 0.05 or 0.1% ASA from 8 to 16 wk of age. Rectal body temperature was significantly decreased by feeding 0.05 and 0.1% ASA. Hen-day egg production was significantly increased for quails fed the diet containing 0.05% and 0.1% ASA. Shell thickness seemed to be thicker at the higher levels of ASA. Serum T3 concentration was decreased significantly (P≤0.05) in quails fed 0.1% ASA (0.38ng/ml) in comparison with controls (0.62ng/ml), but serum T4 concentration was not significantly affected. Dietary ASA had a positive effect on humoral immunity and quails fed 0.05 and 0.1% ASA had a significantly higher total antibody titer compared to other treatments. ASA treatments caused a significant decrease in serum cholesterol, glucose and hepatic TBARS as an indicator for lipid peroxidation, as well as enhancement in the activity of antioxidative enzymes GSH-Px and SOD in a dose dependent manner. These antioxidative effects were accompanied with a significant reduction in corticosterone levels due to ASA treatments. Therefore, it could be concluded that feeding diets containing 0.05 or 0.1% ASA during the summer season could have potential benefits for poultry welfare and productivity because of reducing body temperature and oxidative stress, which consequently allowing more physiological resources to be used for responding to environmental stressors.

Selection for reproductive traits in white egg stock using independent culling levels

The objective of this study was to report the response to selection for fertility and hatchability in white egg layers strains, based on sire and dam performance, and the effects of inbreeding on these traits. Two selected white egg strains (CC and DD) from Embrapa´s poultry program under multiple trait selection were compared to a control strain (CCc). The control strain was established by randomly mating one male from each sire family to a non-related female from each dam family and was used to monitor genetic change in the selected lines. CC and DD were selected using family and individual information on hen-day egg production up to 40 weeks of age, egg weight, sexual maturity and 16-week-old body weight over five generations. Independent culling levels (ICL) were also used during population expansion to eliminate sires and dams with low fertility (FERT) and hatchability (HATC). Initially, FERT and HATC were over 90.0% in both selected and control strains. FERT and HATC of the selected and the control strains were compared during the last generation. FERT averages were 93.8, 93.8 and 94.4%, and HATCH averages were 93.2, 91.6 and 93.1% for CC, DD and CCc respectively. FERT and HATCH means were not different among strains. Estimated inbreeding increased at a rate of 0.4% per generation in all strains. Selection using ICL was able to effectively maintain the high initial FERT and HATC levels, and provide potential for high selection intensity in other traits. Inbreeding depression was not observed for any trait, indicating that selection compensated for any negative effects of inbreeding.

Twenty-five hydroxycholecalciferol as a cholecalciferol substitute in broiler breeder hen diets and its effect on the performance and general health of the progeny

An experiment was conducted with broiler breeder hens to determine the relative biological value of 25-hydroxycholecalciferol (25-OHD3) compared with cholecalciferol (vitamin D3) for hen-day egg production, hatchability, embryo mortality (early, 1 to 10 d of incubation, late, 11 to 21 d), and body ash of the progeny. The study was conducted with 73-to-90-wk-old molted Ross broiler breeder hens in an environment excluding ultraviolet light. A basal vitamin D3 deficient diet supplemented with 4 levels of vitamin D3 (0, 3,125, 12,500, and 50,000 ng/kg of diet) and 2 levels of 25-OHD3 (3,125 and 12,500 ng/kg of diet) was fed. The relative biological values of 25-OHD3 in comparison to vitamin D3, using slope ratio techniques, were 138, 133, 128, and 111% for hen-day egg production, hatchability, late embryo mortality, and body ash of the progeny, respectively (average = 128%). When comparing 25-OHD3 against D3 at the 3,125 ng/kg level, the relative biological values were 209, 167, 400, and 108% for the same criteria, respectively (average = 221%). However, at the 12,500 ng/kg level no statistical differences between 25-OHD3 and D3 were observed (average = 108%). Four trials were conducted to determine the effect of the maternal diet on the performance and leg abnormalities of the hens’ progeny. In experiment 1, no vitamin D was added to the corn-soybean meal basal diet fed to the chicks, and in experiments 2, 3, and 4 the basal diet was supplemented with 27.5 microg of D3/kg of diet. In the progeny study, the average relative biological value of 25-OHD3 at the 3,125 and 12,500 ng/kg levels were 115 and 101%, respectively. The potency of 25-OHD3 in relation to vitamin D3 depended on the level tested. When comparing vitamin D sources, 25-OHD3 had greater potency than D3 only at very low levels of supplementation.

Comparison of the Egg Characteristics of Different Sudanese Indigenous Chicken Types

Three local types of Sudanese indigenous fowls, large Baladi (LB), Bare-neck (BN) and Betwil (BT) were studied for detection of maturity live weight and egg characteristics. The (BN) average live weight (1547.2±274.5 gm) was heavier than either (LB) (1494.4±349.8 gm) or (BT) (1198.3±257.5 gm), The Betwil average live weight is significantly (P<0.05) lighter than those of other two local types. The weekly hen-day egg production means were 3.7, 3.2 and 3.9 for (BN), (BT) and (LB) respectively, while the corresponding hen-housed egg production means were 3.3, 2.7 and 3.4. The rate of egg production during the laying period (36 weeks) was 47.14, 38.57 and 48.57 for (BN), (BT) and (LB) respectively. There were significant differences (P<0.05) in average egg-shell thickness among local types. The means of egg-shell thickness for (BT) and (BN), 36.2±4.2 and 36.2±4.0µ respectively were similar and both significantly thicker than that of (LB), 34.3±3.6µ

Effects of Adding Methionine in Low-Protein Diet on Production Performance, Reproductive Organs and Chemical Liver Composition of Laying Hens under Tropical Conditions

This study was conducted to determine the effects of adding DL-methionine (Met) in low-protein diet (Low-CP; 14% CP) on egg production, reproductive organs, abdominal fat and chemical liver composition of laying hens under tropical conditions. Four hundred and eighty commercial laying hens (Isa-brown) during 24-44 weeks of age were fed with the Low-CP diet containing 0.26, 0.30, 0.38 or 0.44% Met. Dietary protein 16% CP with 0.38% Met was offered as the positive control group. The results showed that hen-day egg production, egg mass and feed conversion ratio of hens received Low-CP diet with 0.26% Met was the worst among experimental groups (P<0.01). Increasing Met to 0.44% could improve hen-day egg production and egg weight as same as the control group, although FCR and egg mass of all Low-CP diet with various levels of Met were still significantly poorer (P<0.05). Interestingly, adding synthetic Met to Low-CP diet resulted in significant reduction of mortality rate compared to the Low-CP diet without adding Met and the control group (P<0.05). Hens received Low-CP diet with 0.44% Met had lower yolk egg percentage than 0.26% Met group. Moreover, higher eggshell thickness, ovary weight, oviduct weight and abdominal fat weight in supplementing Met groups were observed (P<0.05). However, adding Met could not achieve development of reproductive organs compared to the control. Liver fat and abdominal fat contents were linearly increased with the Met supplementation, while the liver protein was inversely reduced (P<0.05). In conclusion, the adding Met in Low-CP diet may give advantage to the hen raised under hot climate, particularly in case of mortality rate and eggshell thickness.

Evaluation of Cellulolytic Enzyme Supplementation on Production Indices and Nutrient Utilization of Laying Hens Fed Soybean Hull Based Diets

A 120-day feeding trial was conducted to evaluate cellulolytic enzyme supplementation on production indices and nutrient utilization of laying hens fed soybean hull based diets. Seven experimental layers diets were formulated incorporating soybean hull meal at 0%, 10%, 20%, 30% (without enzyme supplementation) and 10, 20 and 30% (with 2.0% enzyme supplementation) dietary levels respectively. One hundred and forty seven (147), Shikka brown layers already 12 months in lay were divided into 7 groups of 21 birds each and randomly assigned to the 7 treatment diets in a completely randomized design (CRD). There were significant differences (P 0.05) among the groups in body weight, egg yolk colour, shell thickness, albumen and yolk indices, horizontal and oblong circumferences and digestibility of dry matter and ash respectively. The group on 30% dietary level of soybean hull meal (without enzyme supplementation) performed significantly (P<0.05) better than the other groups in hen-day egg production, feed cost/dozen eggs and egg weight. The results of this experiment suggest that 2.0% safzyme cellulolytic enzyme supplementation at 30% dietary level of soybean hull meal in layer diet could not significantly affect the performance of laying hens.

Use of Distillers Dried Grains Plus Solubles in Laying Hen Diets

A major emphasis on ethanol production in the US has led to the construction of new ethanol plants and an increased production of distillers dried grains plus solubles (DDGS). In the past DDGS came largely from the beverage industry and consisted of several grains used during fermentation. Recently, a majority of the DDGS produced is from corn fermentation for ethanol production. Little research has been conducted to test the use of this new generation DDGS from modern ethanol plants in laying hen diets. Hy-line W-36 laying hens were used to test an elevated inclusion level of DDGS from modern ethanol plants that can be incorporated into layer diets. Hens were fed a commercial or low-density diet formulated to contain 0 or 15% DDGS for 25 to 43 wk of age. No differences were observed in the majority of parameters evaluated between hens fed 0% or 15% DDGS. However, there was a significant (P < 0.05) reduction in hen-day egg production through 35 wk of age when hens were fed the low-density diet with 15% DDGS. Hens fed the commercial diet with 15% DDGS had numerically lower egg production to 32 wk of age, but this was not statistically significant. Distillers dried grains plus solubles proved to be an acceptable feed ingredient for laying hen diets. A suggested maximal inclusion level of 10 to 12% DDGS, based on these data and previous research, may be used in commercial diets, but it is speculated that DDGS should be incorporated at lower levels in low-density diets.

Effect of dietary phosphorus and phytase levels on the reproductive performance of large white turkey breeder hens

An experiment was conducted to determine the effect of dietary P levels and dietary phytase enzyme (E) inclusion on Large White turkey breeder hen reproductive performance from 31 to 62 wk of age. Hens were placed in a curtain-sided house with 48 pens (10 birds per pen; 8 pens per treatment) at 31 wk and were fed a breeder ration with treatments as follows: HP, dietary available P = 0.55%; HPE, HP + E; MP, dietary available P = 0.35%; MPE, MP + E; LP, dietary available P = 0.17%; and LPE, LP + E. Feed and water were available ad libitum for 28 wk of lay. Diets were fed in mash form, and all other nutrients were formulated to meet or exceed NRC requirements. All hens were photostimulated in January (31 wk) with 15.5 h of light daily. Production data were recorded on a pen basis. Individual bird BW and feed consumption, by pen, were determined at monthly intervals from 31 to 62 wk. Hens were observed for weekly reproductive performance for hen housed egg production, hen-day egg production, settable eggs, cumulative settable eggs, hens out of lay, and hen mortality and for biweekly performance for egg fertility, hatchability of all eggs, hatchability of fertile eggs, egg weight loss, conductance, conductance constant (k), and embryonic mortality. Egg weight, eggshell thickness, egg components, and albumen and yolk P were measured monthly. At 62 wk of age, hen tibia P, plasma P, total fecal P, and water-soluble fecal P were determined. Decreasing dietary P resulted in no decreases in reproductive performance for turkey breeder hens to 62 wk. Additionally, decreased dietary P resulted in decreased total fecal P and water-soluble fecal P. Feeding turkey breeder hens dietary phytase enzyme resulted in significantly fewer hens going out of lay; however, this was not reflected in hen housed egg production. It was concluded that phosphorus could be lowered in turkey breeder hen diets, compared with current surveyed industry levels, without impairing reproductive performance.

Effect of Chronic V.S. Intermittent Exposure to T-2 Toxin on Reproductive Performance in Bobwhite Quail

Studies were conducted to determine the effect of chronic v.s. intermittent exposure to T-2 toxin on reproductive performance in adult bobwhite quail. In Experiment 1, 180 hens were orally dosed with 0% (LD ), 20% (LD ), 40% (LD ) or 60% (LD ) of the acute 100% lethal dose of T-2 toxin as determined in a 0 20 40 60 previous experiment. One quarter of the dosage was administered each week for 3 weeks. Date of puberty was delayed 5 days as a result of the highest dose of T-2 toxin. There were no differences (P>0.05) in henday egg production or fertile hatchability of eggs as a result of intermittent exposure to T-2 toxin. Fertility and total hatchability of eggs collected from LD hens during week 2 following puberty were less (P#0.05) than 60 from control hens. In Experiment 2, 139 hens were fed 0, 12, 16 and 20 mg T-2 toxin/kg feed for a 4 week period. Puberty was delayed 11 days among hens fed 20 mg/kg feed as compared to hens not fed T-2 toxin. Similarly, feed consumption was less (P 0.05) in total hen-day egg production was found. However, percent fertility and total hatchability of eggs were lower (P<0.005) among hens receiving 20 mg T-2 toxin/kg feed as compared to control hens during the first 7 days following puberty. Results from these studies indicate that reproductive failure in wild bobwhite quail may be a consequence of mycotoxin exposure.

Organic farming production. Effect of age on the productive yield and egg quality of hens of two commercial hybrid lines and two local breeds

Hens of 2 hybrid lines (Hy Line Brown - HLB, Hy Line White - HLW) and 2 local breeds (Robusta maculata – RM and Ermellinata of Rovigo – ER) were reared following the organic production procedure and their egg yield and quality were studied at two different ages (30 and 42 weeks). The experimental period was between 26 and 42 weeks of age, starting in summer and lasting until autumn. Age significantly (P<0.01) affected the hen-day egg production and the daily egg mass of the HLB (84 vs. 94% and 44.5 vs. 59.4 g), of the HLW (81 vs. 89% and 42.4 vs. 54.7 g) and of the RM hens (27 vs. 63% and 12.9 vs. 36.7 g), which was the least precocious. Age did not affect the daily egg production of the ER hens (which was maintained around 58%), although it was observed a slight (P<0.05) increase of the daily egg mass (28.6 vs. 32.1 g). Age increased (P<0.01) the egg weight, yolk colour, yolk percentage and yolk:albumen ratio and decreased the albumen percentage in all groups.

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.

The Effect of Incorporating Different Levels of Locally Produced Canola Seeds (Brassica napus, L.) In the Diet of Laying Hen

Research in King Faisal University proved that canola seeds can be successfully planted in Al- Hassa area of Saudi Arabia. The objectives of this study were to determine the chemical analysis and metabolizable energy of a locally produced full fat canola seeds (LPFFCS). Also to determine the possibility of using locally produced canola seeds in the layer diet. The chemical analysis of the seeds showed that it contained 95.4% DM, 25.6% CP, 38.2% EE, 4% ash and 6.8% CF. ME, calculated from the determined TME showed a 4128 Kcal/kg value. Essential and non-essential amino acids were also determined as well as Na, Cl, Ca, P, Cu. Zn and Fe. It was concluded that with the exception of protein level canola seeds are very much similar to SBM in many aspects. Five levels of whole canola seeds; 0, 5, 10, 20 and 30% were used in the diets of 100 white leghorn pullets at age of 20 weeks. The results of this experiment showed that including up to 10% whole canola in the layer diet made no harm to the performance of these birds in terms of hen-day egg production, egg mass, feed conversion and egg weight. Feed intake increased with increasing level of canola seeds in the diet. However most of these differences were season dependent. Hen-day production, egg mass and egg weight were very much lower when birds fed 30% canola. The highest production rate was found in the fall season when birds fed 5 and 10% canola seeds (90 and 88%, respectively). No specific trend was observed on the effect of canola on egg specific gravity and yolk index. However, haugh unit was higher, yolk color was darker, weight gain was lower in birds fed 30% canola seeds. It was concluded that incorporating up to 5% LPFFCS in the layer diet might benefit the producer if economically priced.

The effect of dietary inclusion of meat and bone meal on the performance of laying hens at old age

The effect of the inclusion of meat and bone meal (MBM) in the diet of old laying hens on their egg production and the quality of their eggs was investigated. Meat and bone meal containing a high concentration of ash and a low concentration of crude protein was included at levels of 2.0, 4.0 and 6.0% in the diets and fed for 20 weeks. Forced moulted 84-week old laying hens (Brown-Nick) were divided randomly into four treatment groups of 120 hens each. The inclusion of 2.0% MBM to the layer diet increased hen-day egg production significantly, whereas inclusion in excess of 2.0% MBM had no additional beneficial effect on egg production. However, the inclusion of dietary MBM at all three levels depressed egg weight. There were no significant effects of dietary treatments on egg weight, feed intake and feed conversion ratio of the hens. The specific gravity of the eggs from hens fed the control diet was significantly lower than from those receiving the diets containing 2.0 and 4.0% MBM. The Haugh Unit value of eggs in the 6.0% MBM treatment was significantly higher than the other treatments. There were no significant effects of MBM inclusion on yolk colour score, yolk height, eggshell thickness, eggshell weight and eggshell strength. However, MBM inclusion in a diet had a significant beneficial effect on eggshell quality. The eggshell ratios of the 2.0, 4.0 and 6.0% MBM treatments were significantly higher than in the control diet, while the cracked/broken egg ratio was significantly lower. In conclusion, inclusion of MBM containing a high ash and low crude protein content to conventional maize-soya bean diet improved egg production performance of laying hens. The dicalcium phosphate level in the diet could also be reduced without any adverse effects on egg production and egg quality.

Effect of phytase supplementation of diets with different levels of phosphorus on performance and egg quality of laying hens in hot climatic conditions

Four hundred and eighty 54-week old Nick-Brown hens were assigned to four dietary treatments. Each treatment consisted of four replications of 10 cages (three hens per cage). The experimental diets were: 4.5 g available phosphorus (aP)/kg without phytase (control); 4.5 g aP/kg with phytase; 3.0 g aP/kg without phytase; 3.0 g aP/kg with phytase. Commercial microbial phytase, Natuphos(R), was added at 300 phytase unit (FTU) /kg diet. Diets were isonitrogenous (16.5% crude protein) and isoenergetic (11.5 MJ, ME/kg). Criteria evaluated included egg production, feed consumption, feed conversion, proportion of cracked/broken eggs, egg weight, eggshell weight, eggshell strength, eggshell thickness and body weight. Phytase supplementation to the control diet (4.5 g aP/kg) and the low 3.0 g aP/kg diet significantly increased hen-day egg production from 75.49 to 77.96% and from 64.59 to 76.54%, respectively. Average daily feed consumption was significantly different between treatments: Phytase supplementation to the control and the 3.0 g aP/kg diets increased daily feed consumption significantly from 101.31 to 103.43 g/day and from 95.24 to 101.69 g/day, respectively. There were no significant differences between the treatments in eggshell weight, eggshell thickness, eggshell strength and cracked/broken eggs. Phytase supplementation to the control (4.5 g aP/kg) and the 3.0 g aP/kg diets increased egg weight significantly from 62.66 to 64.32 g. and from 62.49 to 63.98 g, respectively. The beneficial effects of phytase supplementation to laying hen diets were clearly evident under the high ambient temperatures pertaining to this study. Hens consuming the 3.0 g aP/kg diet with phytase performed as well as hens fed the diet containing 4.5 g aP/kg without phytase. Key Words: Phytase, Laying hen, Available phosphorus, Performance, Ambient temperature SA Jnl Animal Sci Vol.34(1) 2004: 13-17

Evaluation of Microdesmis puberula Leaf Meal as Feed Ingredient in Laying Hen Diets

A fifty-day feeding trial was conducted to evaluate the leaf meal of Microdesmis puberula as feed ingredient in laying hen diets. Microdesmis puberula is a preferred tropical browse plant. Seven experimental layers diets were formulated incorporating the leaf meal of Microdesmis puberula at 0.0, 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0% dietary levels. One hundred and five (105), Shikka brown layers already 10 months in lay were divided into 7 groups of 15 birds each and randomly assigned to the 7 treatment diets in a completely randomized design (CRD). There were no significant differences (p<0.05) in body weight, Haugh unit, Shell thickness, Yolk index and Albumin index among the groups. However, there were significant (p<0.05) differences among the groups in hen-day egg production, egg weight, feed intake, egg size and dressed carcass weight. The intensity of the egg yolk colouration increased with increasing levels of the leaf meal in the diets. The results of this study suggest that 15% dietary inclusion of Microdesmis puberula leaf meal could be used in layers diets without any deleterious effects on performance.

Interrelationship between environmental temperature and dietary nonphytate phosphorus in laying hens

Four experiments were conducted to evaluate the effects of phosphorus nutrition on laying hens exposed to heat stress (HS). Hens were fed their respective diet for at least 3 wk prior to initiation of each experiment to allow the hens fed low-P diets to become P deficient. In most experiments, hens housed in non-HS conditions were pair-fed to the HS hens to maintain equal feed intake. In experiments 1 and 2, two levels of nonphytate P (NPP; deficient at 0.10 or 0.16% vs. control at 0.45%) and two temperatures (constant thermoneutral at 21 degrees C or cyclic HS up to 35 degrees C) were evaluated. Low NPP significantly reduced feed intake and hen-day egg production, but the cyclic heat treatment had no effect on hen performance. Experiment 3 was similar to experiments 1 and 2 except that constant HS was implemented. Both constant HS and low dietary NPP reduced feed intake and egg production, and there was no significant interaction between HS and dietary NPP level. In experiment 4, hens were fed 0.10 or 0.45% NPP diets and exposed to a more severe HS (38 degrees C) for 8 h. Hens fed the deficient NPP level showed a 16% incidence of severe heat distress (unable to stand, unresponsive). Our results generally indicated that there was no interaction between dietary NPP level and HS in laying hens. However, subjecting hens that had been fed a P-deficient diet to an acute HS of 38 degrees C did increase the incidence of severe heat distress.