Abstract: Background and Objective: This study was conducted to evaluate the effects of supplementation of Lysophosphatidylcholine (LPC) in diets on production performance, egg quality and intestinal morphology of laying hens. Materials and Methods: A total of 288 commercial laying hens (Lohmann brown-classic) from 33-46 weeks of age were used in this study. The hens were divided into 3 groups of 8 replications with 12 hens each. According to the experimental groups, hens were fed as 1) control diet, 2) control diet with 0.05% LPC and 3) control diet with 0.10% LPC. Results: At the end of the trial, supplementations of LPC (0.05 and 0.10%) significantly improved feed conversion ratio (FCR), increased egg size, decreased feed intake and reduced feed cost per egg weight (FCE) (p<0.01), although significant effect on percentage of egg production, egg weigh and egg mass were not observed. Neither of internal and external egg qualities were influenced by LPC supplementation. In term of morphology, adding LPC significantly decreased villi height in the segment of duodenum and conversely increased in the jejunum (p<0.05). Conclusion: It is concluded that supplementation of LPC may improve nutrients utilization (digestion or/and absorption) via the modification of gut morphology.
INTRODUCTION
The egg yolk is a single massive cell weighing about 17-20 g in an average egg and is comprised of 51-52% water, 16-17% protein and 31-33% fat1. Fat is the largest nutritive component of egg yolk (65% triglyceride, 28% phospholipids and 7% cholesterol) and there are many biological functions of fat such as precursor of hormone, energy reserve, composition of cell membrane as well as fat soluble vitamins2. Therefore, the utilizations of fat (digestion, absorption and metabolism) in laying hen is important for egg production.
Lysophosphatidylcholine (LPC) is mono-acyl derivatives of phospholipids resulting from the action of phospholipase A2, which hydrolyse the ester bond at sn-2 position3. It is an important metabolite produced by many cells and are widely distributed in a variety of tissue and are capable of increasing ion permeation in membranes, alter mucosal barrier function4 and modify the activity of various membrane associated enzymes5. In term of animal productions, supplementing LPC increased egg weight due to the increment of egg yolk weight of laying hens2,6 improved body weight gain during starter period7 and FCR of broiler chicks8 improve broiler performance through increasing nutrient utilization9,10, increased weight gain and nutrient digestibility of weaning pig11,12. Although, could not found any improvement in lipid digestibility during finishing period of pigs fed LPC13.
During peak egg production period, the hens require high nutrients to support their productivity. The improvement of gut morphology by supplementing LPC may promote egg production performance of laying hens. Therefore, this study was conducted to evaluate the effect of supplementing LPC in diet on egg production, egg quality and intestinal morphology of laying hens.
MATERIALS AND METHODS
Animal and management: A total of 288 laying hens were used for 12 weeks (from 33-46 weeks of age) and kept under an evaporative cooling system to control air ventilation and temperature. The hens were divided into 3 experimental groups. Each group was consisted of 8 replications and 12 hens each. The hens were kept in wire cages with 4 hens per cage and the lighting program was set 16 h. Feed and water were offered ad libitum.
Experimental diets: The experimental diets were based on corn-soybean, all nutrient requirements were provided according to the Lohmann14 Brown Management Guide. Feed ingredients and nutrients composition are presented in Table 1. The diets were assigned as (1) control diet (corn-soybean meal diet) (2) control diet with 0.05% LPC (3) control diet with 0.10% LPC. The Lysophosphatidylcholine (LPC) is offered from Devenish Nutrition (Belfast, North Ireland) and marketed under the trade name Lipidol® (50% lysophosphatidylcholine along with an inert calcium silicate carrier).
Egg production and egg quality: Egg production performance from 33 to 46 weeks of age were recorded. Percentage of egg production and egg weight were collected daily. The eggs are graded according to egg weight (Size 0 ≥70 g, Size 1 ≥65 g, Size 2 ≥60 g, Size 3 ≥55 g, Size 4 ≥50 g) at four days interval. Feed consumption and egg mass (g hen–1 day–1) were used to calculate FCR (kg feed kg–1 egg mass). Feed cost per egg weight (FCE; Baht kg–1 egg) and mortality (%) were also determined.
| Table 1: | Feed ingredients of experimental diets and chemical composition of experimental diets |
*Premix: Consist of vitamin A: 5.0 MIU, D3 MIU: E 4,000 IU. K3: 0.6 g, B1: 0.8 g, B6: 1.2 g, B12: 0.0025 g, Nicotinic acid: 5.00 g, pantothenic acid: 3.76 g, Folic acid: 0.2 g, Biotin: 0.036 g, Mn: 24.00 g, Zn: 20.00 g, Fe: 16.00 g, Cu: 4.00 g, Iodine: 0.8 g, Co: 0.08 g, Se: 0.04 g and Carrier added to 1.00 kg premix |
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Four eggs from each replication that have weight close to the replication's mean were chosen twice a week to analyze egg qualities such as specific gravity, shell thickness (mm), albumen height (mm), albumen weight (g), yolk weight (g), eggshell weight (g), albumen (%), yolk (%), eggshell (%), albumen:yolk ratio, Haugh units and yolk color.
Intestinal morphology: Tissue samples of 32 hens were collected at the end of the experiment. One hen per replication was randomly selected from each pen and stunned with CO2 and slaughtered and entire gastrointestinal tract was removed the stomach and selected three different locations of the small intestine. Tissue sample for morphological measurements were taken from the duodenum (5 cm from the pylorus), jejunum (5 cm posterior to the yolk stalk) and ileum (2 cm anterior to the ileocecal valve) rinsed in physiological saline, every sample about 2 cm in length fixed in phosphate-buffered formalin (10% formalin, pH = 7.6). Histological slides were prepared from 2 cross-sections (5 um thick) of each intestinal sample, processed in low-melt paraffin and stained with hematoxylin-eosin to evaluate morphological parameters15.
Statistical analyses: Data were analyzed using ANOVA (two-way) in a completely randomized design. Differences among treatment means were tested for significance by using the Duncan’s multiple range tests at 5% significance level16.
RESULTS AND DISCUSSION
Productive egg performance: The effects of LPC on egg production performance are shown in Table 2 and 3. Percentage of egg production, body weight, egg weight and egg mass were not significantly affected by LPC supplementation. However, supplementing LPC (0.05 and 0.10%) in diet result in lower feed intake, FCR and feed cost per egg (FCE) (p<0.01). Moreover, the number of large size egg (Grade 0: ≥70 g) was significantly high (p = 0.05), while the medium size (Grade 2: 60-64 g) was low by LPC supplementations (Table 3).
Percentage of egg production, egg weight and body weight were not significantly influenced by LPC supplementations. These are in agreement with Han et al.2 and Melegy et al.17 who reported that LPC did not affect these productive traits. However, it is clear that LPC decrease feed intake and improve FCR. It can be implied that supplementing LPC may enhance digestibility and/or absorption of the nutrients. Accordingly, Han et al.6 reported that supplementing LPC in diet improved FCR due to the increase of nutrients digestibility, decreased feed intake and increase egg weight. Also, Zaefarian et al.18 found a significant decrease in feed intake in broilers fed diets containing 3.5 kg t–1 of LPC. In agreement with Han et al.2 this study also found high number of large (≥72.9 g) size eggs with a concomitant reduction in the number of medium (53-62.9 g) size eggs when fed diet supplemented with LPC. It is possible that LPC may improve fat utilization and energy due to its emulsifying properties and/or increase of nutrient absorption via increasing micelle formations6,11,19,20.
Egg quality: There were no significant effect of LPC on egg quality such as specific gravity, albumen height, shell weight, yolk weight, albumen weight, shell weight, Haugh units, albumen:yolk ratio, shell thickness, yolk color and eggshell strength (Table 4).
| Table 2: | Effect of LPC supplementation in diet on egg production performance of laying hens |
| A,B,CMeans within the same row without the same superscript letter are significant different (p<0.05), FCE: Feed cost per egg weight 1 kg | |
| Table 3: | Effect of LPC supplementation in diet on egg size of laying hens |
| Size 0: ≥70 g, Size 1: ≥65 g, Size 2: ≥60 g, Size 3: ≥55 g, Size 4: ≥50 g A,B,CMeans within the same row without the same superscript letter are significant different (p<0.05) | |
| Table 4: | Effect of LPC supplementation in diet on egg quality of laying hens |
| Table 5: | Effect of LPC supplementation in diet on Intestinal morphology of laying hens |
| A,B,CMeans within the same row without the same superscript letter are significant different (p<0.05) | |
In accordance with Han et al.6 who reported no significant effects of LPC supplementation on egg shell weight, yolk color and Haugh units. This study also did not find any effect of LPC on internal and external characteristic of egg. In exceptional, the tendency of increase of albumen weight (p = 0.06) was found when LPC was supplemented. Previous reports indicated that supplementing LPC increased egg weight by increase of albumen weight or yolk weight2. However, the change of albumen weight due to LPC supplementation could be explained.
Intestinal morphology: Morphology of the small intestine of hens is shown in Table 5. Supplementation of LPC significantly decrease villous height in the segment of duodenum, while the villous height in the jejunum were increased (p<0.05). The villus height:crypt depth ratio in the segment of jejunum tend to be increased when LPC was supplemented at 0.05% (p = 0.07). There were no significant effects of LPC on the other intestinal morphology observations.
The physiological functions of the gastrointestinal tract are dependent on the nutrition and quantity of feed21 and morphology of small intestine is one of indicative biomarkers to determine gut health22 LPC supplementation decreased duodenal villus height and increased jejunal villus height. In feed restriction studies, body weight of rabbit was declined, whereas duodenal villus height was increased23,21. This indicates that duodenal villus height is not always positively correlated with the growth performance of animal. Although, major absorption of nutrients occurs in the duodenum and proximal jejunum22. In fact duodenum is the digestive site of small intestine and the main absorptive site is jejunum. Feeding of LPC increase coefficient of total tract apparent digestibility of fatty acid in broiler diets24,7. Boontiam et al.19 reported that LPC can function as a membrane transducer by diffusing rapidly through the lipid portion of cellular membranes to increase fluidity and permeability. Therefore, FCR of the hens fed LPC should be improved via the increase of nutrients absorption and/or transportation (jejunal morphology).
CONCLUSION
In this study, supplementation of LPC in the diet of laying hens may improve egg performance (FCR, FCE and egg size) via the enhancing of nutrient absorption (increase of villous height of Jejunum).
SIGNIFICANCE STATEMENT
This study discover the improvement of gut morphology at the segment of jejunum by the supplementation of LPC that can be beneficial for nutrient utilization (FCR) and egg production (egg size). This study will help the researcher to uncover the critical areas of gut health and phospholipids supplementation that many researchers were not able to explore. Thus a new theory on phospholipids modification, small intestinal morphology and egg production may be arrived at.
ACKNOWLEDGMENT
The author gratefully acknowledges that the funding has come from Easy bio (South Korea) Technology Company. The author also appreciated the Center of Advanced Study for Agriculture and Food and Feed Analysis Laboratory of Department of Animal Science, Bangkhen Campus, Kasetsart University, Thailand for the suggestion, guidance and support throughout this trial.