Effects of exogenous energy on synthesis of steroid hormones and expression characteristics of the CREB/StAR signaling pathway in theca cells of laying hen

Energy and the cAMP-response element binding protein (CREB)/steroidogenic acute regulatory protein (StAR) signaling pathway play important roles in steroid hormone production and follicular development in hens. This present study aimed to investigate the effects of exogenous energy on the synthesis of steroid hormones and the expression characteristics of the CREB/StAR signaling pathway in theca cells of laying hen. The primary theca cells of small yellow follicles were randomly divided into 6 treatments and cultured in medium with glucose concentrations of 1, 1.5, 3, 4.5, 6, and 7.5 mg/mL for 48 h. It was found that growth was robust and cell outlines were clear when cells were cultured with 1, 1.5, 3, and 4.5 mg/mL glucose, but cell viability was diminished and cell density decreased after exposure to glucose at 6 and 7.5 mg/mL for 48 h. Cell viability showed an increasing and then decreasing quadratic response to increasing glucose concentration in culture (r2 = 0.688, P < 0.001). The cell viability of theca cells cultured with 4.5 mg/mL glucose was greater than those cultured with 1, 1.5, 6, and 7.5 mg/mL glucose (P < 0.05). The concentration of estradiol in the medium containing 3 mg/mL glucose was higher than in medium containing 1, 1.5, and 6 mg/mL glucose (P < 0.05). There was an increasing and then decreasing quadratic correlation between progesterone concentrations and glucose concentrations (r2 = 0.522, P = 0.002). The concentration of progesterone in medium with 4.5 mg/mL glucose was higher than in medium with 1 and 7.5 mg/mL glucose (P < 0.05). There was an increasing and then decreasing quadratic correlation between the relative expression of CREB1 (r2 = 0.752, P < 0.001), StAR (r2 = 0.456, P = 0.002), CYP1B1 (r2 = 0.568, P < 0.001), and 3β-HSD (r2 = 0.319, P = 0.018) in theca cells of laying hens and glucose concentrations after treatment with different glucose concentrations for 48 h. After treatment with 4.5 mg/mL glucose, the expression of StAR, CYP1B1, and 3β-HSD genes were increased compared to treatment with 1, 1.5, 3, 6, and 7.5 mg/mL glucose (P < 0.001). There was an increasing and then decreasing quadratic correlation between glucose concentrations and protein expression of CREB1 (r2 = 0.819, P < 0.001), StAR (r2 = 0.844, P < 0.001), 3β-HSD (r2 = 0.801, P < 0.001), and CYP11A1 (r2 = 0.800, P < 0.001) in theca cells of laying hens. The protein expression of CREB1, StAR, and 3β-HSD in theca cells cultured with 4.5 mg/mL glucose was higher than in other groups (P < 0.001). The results indicate that the appropriate glucose concentration (4.5 mg/mL) can improve the synthesis of steroid hormones in theca cells of laying hens through the upregulation of key genes and proteins in the CREB/StAR signaling pathway.

Effects of lysolecithins on performance, egg quality, blood profiles and liver histopathology in late-phase laying hens

1. This study investigated the effects of lysolecithins (LL) on performance, egg quality, blood profiles, relative organ weight and liver histopathology in laying hens.2. A total of 480 healthy 65-week-old Lohmann laying hens were randomly allocated into four treatments in a 2 × 2 factorial arrangement design with two levels of energy (AMEn, 11.08 MJ/kg and 12.94 MJ/kg) and two levels of LL (0 and 0.05%).3. Birds fed high energy diets had lower (P < 0.05) average daily intake and feed conversion rate during weeks 0-4, 5-8 and 0-8, but higher (P < 0.05) average egg weight (AEW) during trial weeks 0-4. There was an interaction in (P < 0.05) AEW during trial weeks 0-14 and 0-8 for energy and LL. The high energy diets increased yolk colour at the end of weeks 2 and 4, while addition of LL increased albumen height at the end of week 2. There was an interaction (P < 0.05) in yolk colour between energy and LL at the end of week 2. There was an interaction (P < 0.05) in serum superoxide dismutase and LDL-C throughout the experiment.4. The high energy diets increased (P < 0.05) the relative weight of abdominal fat compared with low energy diets. The high energy diets increased (P < 0.05) liver ether extract content and liver pathological injury score compared with low energy diets at the end of week 8, while the addition of LL decreased (P < 0.05) liver pathological injury score.5. The supplementation of LL in high energy diets could alleviate some negative effects on liver injury in late laying hens.

Effects of energy restriction during growing phase on the productive performance of Hyline Brown laying hens aged 6 to 72 wk

The aim of this study was to assess the effects of energy-restricted feeding during growing phase on the productive performance of Hyline Brown laying hens aged 6 to 72 wk. A total of 720 six-week-old layer chicks were allocated equally to 3 groups with 6 replicates of 40 pullets each, and were fed 1 of 3 diets that were nutritionally similar except for the apparent metabolizable energy corrected for nitrogen (AMEn) content. At the age of 6 to 17 wk, the pullets in the control group were given diet with 2,850 kcal/kg AMEn, and were fed ad libitum. The levels of AMEn in diet of pullets in the experimental groups were 90% (2,565 [2,850 × 90%] kcal/kg) and 80% (2,280 [2,850 × 80%] kcal/kg) of that in control group, and the daily amount of feed was restricted to the absolute quantity of the diet consumed by pullets in control group. At the age of 18 to 72 wk, all the hens were fed with the same diets ad libitum. As energy restriction increased in the growing phase, body weight (BW) dropped at the ages of 12 and 15 to 23 wk (at 23 wk: P = 0.001; at other ages: P < 0.001), but it showed no significant difference at 24 wk (P = 0.071). At 20 wk, restricting energy induced a delay in the development of sexual organs, including the ovary stroma, oviduct, and small yellow follicle (P < 0.05), as well as a delay in sexual maturity (P < 0.05). Consequently, the laying rate in the first and second periods dropped linearly (P = 0.046, 0.030, and 0.038, P < 0.001, respectively). The coefficient of variation (CV) in the BW at 19, 20, and 21 wk (P = 0.040, 0.023, and 0.042, respectively), the CV of age at first egg (P < 0.001), and CV of individual egg number at age 18 to 72 wk (P < 0.001) decreased linearly. There was a linear increase in the laying rate of hens in the later periods (at age 32-72 wk, P < 0.05), as well as in the average total egg number per hen and average laying rate at the age of 18 to 72 wk (P = 0.006). The average egg mass also showed a linear increase with increasing levels of energy restriction (P < 0.001). In summary, although appropriate energy restriction during growing phase delayed sexual maturity and sexual organ development in early-laying Hyline Brown pullets, it improved uniformity of BW, age at first egg laying, and individual egg number, and increased egg number per hen, laying rate, average egg mass, and number of settable eggs from 18 to 72 wk of age.

Long-term effects of dietary calcium and phosphorus level, and feed form during rearing on egg production, eggshell quality and bone traits in brown laying hens from 30 to 89 weeks of age

The effects of feeding strategies during rearing (0-16 wk) of brown laying hens on mid and end laying performance (30-89 wk) were studied. The rearing feeding strategies followed a 3 × 2 factorial arrangement with feed form; mash with inclusion of 3% finely ground wheat straw (MWS), crumbles with inclusion of 3% finely ground wheat straw (CWS), and crumbles with inclusion of 3% unground oat hulls as fiber sources (COH) at 2 dietary Ca and P levels (high or low Ca-P). Feed conversion ratio improved with COH and MWS compared with CWS from 30 to 59 wk. Rate of lay and egg mass production showed a feed form × Ca-P interaction from 60 to 89 wk. Low Ca-P led to a higher egg production, but only when COH and MWS were fed. BW at 89 wk was higher with CWS compared to COH and MWS. BW uniformity was better with COH compared to MWS at 51 wk and both CWS and MWS at 67 wk. Tibia characteristics were not clearly affected by treatment, although there was a feed form × Ca-P interaction on compression at 89 wk, where compression was lower with MWS and low vs. high Ca-P. Low Ca-P during rearing led to higher eggshell thickness, compared to high Ca-P at 45 wk of age, but breaking strength was lower with low vs. high Ca-P at 75 wk. Although eggshell quality was affected by Ca-P and there were some interactions with feed form at some ages, the effect was not consistent. There was no clear relationship between eggshell quality and tibia characteristics. It was concluded that feeding low Ca-P in combination with COH and MWS during the rearing period positively affects egg production during late lay. Also, dietary Ca-P levels, compared to commercial practice, can be lowered during rearing, as this will not affect eggshell quality and bone mineralization at later ages.

Influence of the calcium and nutrient content of the prelay diet on egg production, egg quality, and tibiae mineralization of brown egg-laying hens from 16 to 63 wk of age

The influence of the Ca and nutrient content of the diet fed from 16 to 19 wk of age, on egg production, egg quality, and tibiae mineralization, was studied in brown egg-laying hens from 16 to 63 wk of age. The experimental design was completely randomized with 4 prelay diets organized as a 2 × 2 factorial with 2 levels of Ca (2.5 vs. 3.8%) and 2 standardized ileal digestible Lys (g/kg) to AMEn (Mcal/kg) ratios (DLys:ME; 2.84 vs. 3.13) as main effects. From 20 to 63 wk of age, all hens received a common diet with 2.75 Mcal AMEn/kg, 0.75% DLys, and 3.8% Ca. Each treatment was replicated 18 times and the experimental unit was a cage with 10 hens. Hen production and egg quality traits were measured by period (4 wk), feeding phase (prelay and lay), and cumulatively (16-63 wk of age) and tibiae mineralization was measured at 63 wk of age. During the prelay phase, an increase in Ca delayed egg production (P = 0.065), reduced feed intake (P < 0.05), and increased BW gain (P < 0.01) and percentage of shell of the egg (P < 0.05). An increase in the DLys:ME ratio increased feed intake (P < 0.01) and reduced egg size (P < 0.01). Nutrient content of the prelay diets did not affect hen production during the lay phase, except egg weight that increased (P < 0.05) in hens previously fed the low DLys:ME ratio. Eggshell quality (weight, percentage, strength, and thickness) in this phase was better (P < 0.05) in hens previously fed 3.8% Ca. Cumulatively (16-63 wk of age), hens fed the high Ca prelay diets had better shell quality but tibiae mineralization was not affected. In conclusion, an increase in Ca content of the prelay diet from 2.5 to 3.8% improved shell quality for the entire egg cycle without showing any negative effect on hen production.

Influence of the energy concentration and the standardized ileal digestible lysine content of the diet on performance and egg quality of brown-egg laying hens from 18 to 41 weeks of age

The influence of the energy and the standardized ileal digestible lysine (DLys) content of the diet on egg production and egg quality, was studied in brown-egg laying hens from 18 to 41 wk of age. The experimental design was completely randomized with 10 treatments organized as a 2 × 5 factorial with 2 energy concentrations (2,750 and 2,800 kcal AMEn/kg) and 5 levels of DLys (values varied from 0.66 to 0.78% and 0.67 to 0.79%, for the low and high energy diets, respectively). Each treatment was replicated 10 times (10 hens per replicate). The data were analyzed using the MIXED procedure of SAS with energy concentration and DLys content of the diets as main effects. In addition, the effects of the DLys on the variables studied were partitioned into its lineal and quadratic components. From 18 to 21 wk of age (pre-peak phase), diet composition had limited effects on egg production. From 22 to 41 wk of age (peak phase), however, an increase of 50 kcal AMEn/kg diet increased egg weight (P < 0.05) and tended to improve energy intake (P = 0.083) and feed conversion ratio (P = 0.074). An increase in DLys improved linearly (P < 0.001) egg production, egg weight, egg mass, feed conversion, and energy conversion ratio, and tended to increase BW gain (P = 0.074). Diet composition did not any affect egg quality trait except shell strength that increased linearly (P < 0.05) with increases in the DLys. Cumulatively (18–41 wk of age), egg weight increased (P < 0.05) as the energy and the DLys content of the diet increased. In summary, an increase in energy and DLys content of the diet had limited effects on egg production during the prepeak phase but improved egg production, feed conversion ratio, and BW gain during the peak phase. The data indicate that hens require at least 839 mg DLys/d to maximize egg production in the peak production phase.

Effect of beak trimming at hatch and the inclusion of oat hulls in the diet on growth performance, feed preference, exploratory pecking behavior, and gastrointestinal tract traits of brown-egg pullets from hatch to 15 weeks of age

The influence of infrared beak trimming at hatch (IRBT) and the inclusion of oat hulls (OH) in the diet on growth performance, feed preference, exploratory pecking behavior, and gastrointestinal tract (GIT) development, was studied in brown-egg pullets from 0 to 15 wk of age. The experimental design was completely randomized with 4 treatments arranged as a 2 × 2 factorial with IRBT (sham vs. treated) and OH inclusion (0 vs. 3%) as main effects. Each treatment was replicated 20 times and the experimental unit was a cage with 10 pullets. Feed intake (FI), BW gain, feed conversion ratio (FCR), energy intake (EI, kcal AMEn/d), and energy conversion ratio (ECR, kcal AMEn/g of BW gain) were determined by feeding period (0 to 6, 7 to 10, and 11 to 15 wk of age) and cumulatively. Particle size preference was measured at 7 wk and exploratory pecking behavior of the pullets and at 8 to 14 wk of age. From 0 to 6 wk of age, beak trimming decreased FI (P < 0.01) and increased pullet mortality (P < 0.001) but did not affect BW gain. From 0 to 15 wk of age, OH inclusion improved BW uniformity (P = 0.090) but impaired FCR (P < 0.05) without showing any effect on BW gain or ECR. Preference for coarse particles was greater for the sham than for the treated pullets. Beak trimming and OH feeding reduced (P < 0.05) the exploratory pecking behavior of the pullets from 8 to 12 wk of age but not thereafter. Oat hulls increased the relative weights of the full gizzard and intestines at all ages (P < 0.05). In summary, beak trimming did not affect pullet performance at 15 wk of age or GIT development at any age. Oat hulls improved GIT development at all ages but did not affect BW or ECR. Both beak treatment and OH inclusion affected particle size preference and reduced the exploratory pecking behavior of the birds.

Effects of Dietary Ramie Powder at Various Levels on the Production Performance, Serum Biochemical Indices, Antioxidative Capacity, and Intestinal Development of Laying Hens

The purpose of this study was to investigate the effects of ramie (0, 3, 6, and 9%) included in diets on production performance, antioxidative capacity, serum biochemical indices, and intestinal development of laying hens. A total of 432 Lohmann commercial laying hens were randomly allotted to one of four dietary treatments and fed for 6 weeks. The results showed that the inclusion of ramie had no negative effects on laying performance, and increased (quadratic, P < 0.05) the laying rate with the highest value in the 6% ramie group. However, ramie content in the diet up to 9% reduced the apparent metabolic energy, dry matter, and organic matter apparent digestibility of laying hens compared with those in the 3% ramie group. The content of high-density lipoprotein (HDL-C) in serum was increased (P < 0.05), but the activity of aspartate aminotransferase (AST) was decreased (P < 0.05) by dietary ramie supplementation. As the dietary ramie level increased, the activity of serum glutathione peroxidase (GSH-Px) was increased quadratically (P < 0.05). Compared with control, 3% ramie group significantly increased (P < 0.01) liver total superoxide dismutase (SOD) activity. Meanwhile, the addition of 3∼6% ramie powder increased (P < 0.05) villus height of jejunum and villus height/crypt depth (V/C) of ileum, which reflected the intestinal promotional effect of ramie powder. In conclusion, ramie in a diet of less than 9% might protect the liver and improve the antioxidative capacity with no detrimental impacts on the laying hens. Moreover, it could promote the intestinal mucosal structure and have a positive impact on the intestine health of the laying hens.

Effects of Energy-Restricted Feeding during Rearing on the Performance, Uniformity, and Development of Rugao Layer Breeders at the Initiation of the Laying Period

Simple Summary

Three major factors affecting productive performance of laying hens are BW, flock uniformity, and GIT development at the initiation of the laying period. Various feeding management practices to restrict feed intake of broiler breeders during the rearing phase to optimize BW for reproductive performance can improve BW uniformity. Hence, the feed restriction methods used for broiler breeders might be used to improve flock uniformity and the GIT development of laying hens. The objective of the study was to investigate the effects of energy-restricted feeding and switching to ad libitum feeding on the performance, uniformity, and development of Rugao layer breeders at the initiation of the laying period. Moderate energy restriction from 8 to 18 weeks of age and switching to ad libitum feeding can stimulate the development of the GIT and improve BW uniformity of layer breeders. Improved ECR was observed overall in the experiment. In addition, the BW of layer breeders recovered after the pullets were switched to ad libitum feeding for 3 weeks. These results provide a theoretical basis for the application of energy-restricted feeding in young layer breeders, which may have important practical importance for layer breeders because a better rearing cycle can be advantageous to production performance.

Abstract

The aim of this study was to assess the effects of energy-restricted feeding during rearing on the performance, uniformity, and development of layer breeders at the initiation of the laying period. A total of 2400 8-week-old Rugao layer breeders were randomly assigned to one of five groups (480 pullets per group) with eight replicates and were fed one of five diets that were nutritionally equal with the exception of apparent metabolizable energy corrected for nitrogen (AME_n) content (2850, 2750, 2650, 2550, and 2450 kcal AME_n/kg) from 8 to 18 weeks of age. The daily amount of feed was restricted to the absolute quantity of the diet consumed by laying hens fed 2850 kcal AME_n per kg diet ad libitum (control). From 18 to 21 weeks of age, all hens were fed a basal diet ad libitum. The body weight (BW) of the laying pullets decreased linearly with increasing energy restriction (p < 0.001) but recovered within 3 weeks of ad libitum feeding (p = 0.290). A gradual increase in the degree of energy restriction resulted in a gradual decrease in average daily weight gain (ADG) and a gradual increase in the feed conversion ratio (FCR) and energy conversion ratio (ECR) from 8 to 18 weeks of age (p < 0.001, p < 0.001, p = 0.008). In contrast, the ADG and ADFI (p < 0.001, p < 0.001) gradually increased, while the FCR and ECR (p < 0.001, p < 0.001) gradually improved from 18 to 21 weeks of age. From 8 to 21 weeks of age, ECR improved (p = 0.005) with an increasing degree of energy restriction. The energy-restricted feeding for 6 weeks to the end of the trial improved BW uniformity (p < 0.05). The relative length and circumference of tarsus (p < 0.001, p < 0.001), and the relative weights and lengths of the small intestine, duodenum, jejunum, ileum, and caeca increased linearly (p < 0.001, p = 0.012, p < 0.007, p = 0.012, p = 0.040; p < 0.001, p = 0.003, p = 0.032, p = 0.029, p = 0.040) with increasing energy restriction at 18 weeks of age. After switching to ad libitum feeding for 3 weeks, the relative weights and lengths of the small intestine, duodenum, and jejunum of laying pullets increased linearly with increasing energy restriction (p < 0.001, p = 0.016, p = 0.011; p = 0.009, p = 0.028, p = 0.032). In conclusion, moderate energy restriction (85.97%, 2450 vs. 2850 kcal AME_n/kg) from 8 to 18 weeks of age and switching to ad libitum feeding from 18 to 21 weeks of age can be used to improve BW uniformity and stimulate the development of the duodenum and jejunum of native layer breeders at the initiation of the laying period without compromising BW.

Influence of the energy and digestible lysine contents of the diet on performance and egg quality traits of brown-egg laying hens from 19 to 59 weeks of age

The influence of nutrient density and standardized ileal digestible lys (DLys) content of the diet on egg production and egg quality traits, was studied in brown-egg laying hens from 19 to 59 wk of age. The experimental design was completely randomized with eight treatments arranged as a 2×4 factorial with two AMEn concentrations (2,680 and 2,780 kcal/kg) and four levels of DLys (0.68, 0.72, 0.76, and 0.80%). Each treatment was replicated nine times and the experimental unit was a cage with nine hens. Hen production, egg components (proportion of albumen, yolk, and shell), egg quality traits (Haugh units, egg shell strength, and incidence of broken, dirty, and shell-less eggs) were measured by period (28 d) and cumulatively. Data were analyzed as a completely randomized design with energy concentration, level of DLys, and their interactions as main effects. In addition, the effects of the level of DLys on the variables studied, were partitioned into its linear and quadratic components. No interactions between AMEn and DLys content of the diet were detected for any of the traits studied and therefore, only main effects are presented. An increase in the AMEn concentration of the diet from 2,680 to 2,780 kcal/kg increased energy intake (P < 0.05) and egg weight (P < 0.001) and improved feed conversion ratio (P < 0.05). An Increase in DLys from 0.68 to 0.80% did not affect the number of eggs produced but increased linearly egg weight (P < 0.01) and egg mass production (P < 0.05). Diet did not affect egg quality. In conclusion, an increase in the AMEn content of the diet from 2,680 to 2,780 kcal/kg increased egg weight and improved feed efficiency. Laying hens require no more than 744 mg DLys/d (corresponding to 0.68% DLys) to optimize egg production. However, when the objective is to maximize egg weight, hens should consume at least 843 mg DLys/d (corresponding to 0.76% D Lys).

Effects of energy-restricted feeding during rearing on sexual maturation and reproductive performance of Rugao layer breeders

The aim of this study was to assess the effects of energy-restricted feeding during rearing on the sexual maturation and reproductive performance of Rugao layer breeders. A total of 2,400 8-wk-old Rugao layer breeders were randomly assigned to one of 5 groups (480 pullets per group) with eight replicates and were fed one of 5 diets that were nutritionally similar with the exception of apparent metabolizable energy corrected for nitrogen (AME_n) content (2,850, 2,750, 2,650, 2,550, and 2,450 kcal AME_n/kg) from 8 to 18 wks of age. The daily amount of feed was restricted to the absolute quantity of the diet consumed by laying hens fed 2,850 kcal AME_n per kg diet ad libitum (control). From 18 to 52 wks of age, all hens were fed basal diets ad libitum. The body weight of layer breeders at 18 wks of age decreased linearly with increasing energy restriction (P < 0.001), but caught up within 3 wks of ad libitum feeding (P = 0.290). The coefficient of variation of the body weight of the hens at 18, 21, and 24 wks of age decreased linearly (P = 0.010, 0.025, and 0.041, respectively) with increasing energy restriction during rearing. Energy-restricted feeding delayed sexual organ development at 18, 20, and 22 wks of age, including the number of large yellow follicles, oviduct length, oviduct length index, oviduct index, and ovary stroma index (P < 0.05), and delayed sexual maturity, including the age at laying the first egg and the age at 5% and 50% egg production (P = 0.042, 0.004, and 0.029, respectively). Consequently, egg number from 5% to 50% egg production decreased linearly as the degree of energy restriction increased (P = 0.001) and egg production of hens in the energy-restricted feeding groups was lower than that of hens in the ad libitum feeding group (6.36, 6.43, 6.4, and 4.61% vs. 14.29%; P < 0.05) from 18 to 20 wks of age. Furthermore, egg weight increased linearly as energy restriction increased (P < 0.001) and laying hens in the most severe energy-restricted feeding group had more setting eggs (normal eggs weighing >40 g) than hens in the ad libitum feeding and lighter energy-restricted feeding groups (149.57 vs. 144.34, 142.66, 143.63, and 141.78; P < 0.05). No significant differences were observed in fertility, hatchability of fertile eggs, and hatchability of setting eggs (P = 0.381, 0.790, and 0.605, respectively). In conclusion, moderate energy restriction (85.97%, 2,450 vs. 2,850 kcal AME_n/kg) from 8 to 18 wks of age increased egg weight as well as the production of setting eggs in native layer breeders throughout the laying period, without adverse effects on productive performance from 18 to 52 wks of age, or fertility and hatchability at 52 wks of age.

The effects of dietary calcium and phosphorus level, and feed form during rearing on growth performance, bone traits and egg production in brown egg-type pullets from 0 to 32 weeks of age

In a 3 × 2 factorial arrangement, effects of feed form (crumbles (CWS), mash (MWS), both with inclusion of 3% finely ground wheat straw, or crumbles with inclusion of 3% oat hulls (COH)), and dietary Ca and P (high and low Ca-P) from 0 to 16 wk of age were studied on growth performance, bone characteristics, and gizzard development of egg-type pullets. The cross-over effect of feeding strategy during rearing on laying performance and egg shell quality was studied from 19 to 32 wk of age. From 0 to 16 wk, ADG, ADFI, and feed conversion ratio (FCR) were improved with CWS and COH compared to MWS, but ADG and FCR were improved with MWS compared to CWS and COH from 11 to 16 wk. Uniformity of BW till 11 wk, and tibia breaking strength at 6 and 16 wk were higher with CWS and COH compared to MWS. Tibia ash content at 11 wk and relative empty proventriculus + gizzard weight (EPG) were lower with CWS and COH compared to MWS, also relative EPG at 11 and 16 wk was higher with COH compared to CWS. At 25 wk BW was lower with MWS compared to CWS and COH, but BW was equal for all treatments at 32 wk. The FCR for egg production was improved with COH compared to MWS. Egg shell parameters were not affected by feed form during rearing. Low Ca-P decreased BW uniformity at 6 wk, relative keel bone weight and ash content at 11 wk, tibia ash content at 11 and 16 wk, increased relative EPG at 6 wk, and improved egg shell quality at 32 wk of age. It was concluded that feeding CWS and COH compared to MWS increased growth performance, but had no clear cross-over effect on egg production. Low dietary Ca-P led to a lower bone mineralization during rearing, nevertheless improved egg shell quality at 32 wk.

The effects of the fiber source and xylanase supplementation on production, egg quality, digestibility, and intestinal morphology in the aged laying hen

This study was conducted to evaluate the effects of the fiber source (wheat bran [WB] or sugar beet pulp [SBP]) and xylanase supplementation on production, egg quality, ileal digestibility, intestinal morphology, and gastrointestinal pH in aged laying hens. A total of 540 laying hens (Lohman LSL Lite; 70 wk of lay) were randomized into 10 treatments (6 replicate cages of 9 birds) consisting of a corn soy control supplemented with 0, 3, or 6% WB or SBP with or without xylanase (100 mg of xylanase preparation per kg) for a period of 9 wk in a 5 × 2 factorial arrangement. Hens fed with the diets containing either of the levels of SBP or 6% WB had lower hen-day production, and addition of the enzyme improved hen-day production (P < 0.05), but it could not compensate for the lost production due to the higher levels of either of the fiber sources. Supplementation of 6% SBP to the control diet decreased egg mass (P < 0.05). All fiber-supplemented diets significantly decreased ADFI, which was restored on enzyme addition, with the exception of 3% WB diet. Treatments had no effects on egg weight, feed conversion ratio, egg quality, and serum and carcass traits, except for ileum weight, which was greater in hens fed with the 6% SBP diet (P < 0.05). Adding 3% SBP increased ileal DM digestibility (P < 0.05). Addition of 3% WB improved jejunal villus height, villus height-to-crypt depth ratio, and villus surface area (P < 0.05). Villus surface area, DM, organic matter, and protein digestibility increased as a result of enzyme supplementation (P < 0.05). Cecal pH was reduced on feeding diets containing 3% WB, containing 3% SBP, and with enzyme supplementation (P < 0.05). In conclusion, addition of 3% WB in a corn soy control diet has the potential to improve small intestine morphology in older hens without adverse effects on performance, especially if accompanied by the use of an enzyme, which simultaneously improved morphological traits and nutrient digestibility.

Effects of sunflower meal supplementation in the diet on productive performance, egg quality and gastrointestinal tract traits of laying hens

1. A trial was conducted to study the effects of additional dietary fibre (DF), resulting from partial replacement of soybean meal (SBM) with high-fibre sunflower meal (SFM), on egg production and gastrointestinal tract (GIT) traits in laying hens. 2. A total of 480 Nick Chick white laying hens (21 weeks of age) were randomly assigned to three dietary treatments and fed for 24 weeks. The hens were fed either the control diet based on corn and SBM, which contained 30 g/kg crude fibre (CF) without SFM, or test diets containing 40 g more CF/kg from adding 47 g/kg SFM or 50 g more CF/kg from adding 97 g SFM/kg. Each dietary treatment was replicated eight times (20 hens per replicate). 3. Body weight (P < 0.05), egg production rate (P < 0.05), egg weight (P < 0.01) and egg mass (P < 0.01) linearly increased but feed conversion ratio linearly decreased (P < 0.01) with increasing SFM supplementation. Feed intake, cracked/broken egg ratios and shell less egg ratios were comparable amongst the groups. 4. The egg quality indices were not influenced by dietary treatments, except for the Haugh units, which decreased (linear, P < 0.01; quadratic P < 0.05) when SFM was added. 5. Digestive organ size was not affected by the dietary treatments, but caecum length increased in hens fed SFM (P < 0.05). Digesta pH in the ileum and caecum was reduced linearly (P < 0.01) with SFM supplementation. 6. Small intestine morphology traits improved with 47 g SFM/kg supplementation, whereas negative effects were observed with 97 g SFM/kg. 7. Productive performance of laying hens improved with 40 or 50 g/kg more CF in feed, mostly from SFM supplementation. It was concluded that this performance increase was attributed mostly to the increase in fat content, rather than DF level, when high-fibre SFM was included in layer diets.

Production performance, egg quality, blood biochemical constituents, egg yolk lipid profile and lipid peroxidation of laying hens fed sugar beet pulp

The effect of including sugar beet pulp (SBP) in laying hen diets on performance, egg quality, blood chemistry and egg lipid peroxidation was studied. A total of 200 laying hens were randomly assigned into 4 groups and were offered diets containing SBP at the level of 0%, 3%, 5%, and 7%. The dietary inclusion of SBP linearly (P < 0.01) increased feed intake, egg production, egg weight and mass, and improved feed conversion ratio, yolk color core and Haugh unit. Eggs laid by hens receiving SBP had linearly (P < 0.01) greater protein and lower ether extract. Dietary inclusion of SBP linearly (P < 0.01) decreased egg yolk malondialdehyde, cholesterol, and triglyceride, while increased glutathione peroxidase. Laying hens fed SBP had lower (P < 0.01) serum total lipids, cholesterol, alanine aminotransferase, aspartate aminotransferase, and creatinine. Dietary inclusion of SBP could improve hen performance, health, egg quality, and egg shelf life.