Effects of Prelay Supplementations of Graded Levels of Alphamune R G on the Performance of Laying Hens

This study was carried out to determine the effects of age at prelay (15 and 19 weeks) and dietary supplementation of graded levels of Alphamune G (0.00, 0.04, 0.05, 0.06%) on laying performance of pullet chickens. The experiment period was 17 weeks and completely randomized design was employed. Feed intake, nutrient retention, weight gain and feed to gain ratio values were similar (p > 0.05) among birds fed the different dietary inclusion levels of Alphamune G. Hen day production, Haugh unit and Albumen height were significantly high (p < 0.05) for laying hens of fed the control diet. There was also interaction effect of Alphamune G and Age. The interaction of Alphamune G and Age gave the highest value in laying hens of group B fed the 0.05% diet when compared to the control. However, birds fed the 0.06% Alphamune G inclusion level gave the best result in terms of Production characteristics, Cost to benefit ratio expressed as Cost of feed to produce a Dozen Egg and Egg Quality. Also birds of group B gave better results than that of group A except in the Haugh unit value.


INTRODUCTION
Antibiotics has many possible benefits such as; improvement of feed utilization, reduction of mortality, improvement of weight gain, body weight evenness and feed conversion rate (Bolu et al, 2011). Currently, the use of antibiotics has come under critical reviews since antibiotic resistant bacteria strains can be transferred from the animals to humans consuming the products (Bent and Jesen 2001). Development of alternatives to Antibiotic Growth Promoters (AGPs) is a current research adventure. Organic acids have been reported as promising alternatives to AGPs (Hyden, 2000). It has been reported that gut health is a major determinant of performance and consequently, economics of poultry production (Samik et al., 2007). In the same vein, Dhawale, (2005) opined that the profile of intestinal microflora plays an important role in gut health. One of the promising alternative to Antibiotic Growth Promoter (AGP) that have proven benefits on the overall health of the gut in poultry and other species, is ALPHAMUNE R G. It is produced after autolysis of food grade yeast (Saccharomyces cerevisiae), and it contains a unique combination of (1-3, 1-6) β-glucans and mannan oligosaccharides (mannans) (Alpharma, 2004). The β-glucans, have been reported to enhance the immunocompetence in biological system by binding and activating macrophages (Huff et al., 2007, Solis de los Santos et al., 2007. Mannans have been reported to exert prebiotic effects; they act as a substrate and energy sources for. And in this way enhance the beneficial gut microbiota. The sub-therapeutic dose of Alphamune G is at 500g/tonnes of feed (Alpharma Animal Health, 2004).  reported that 0.04% and 0.06% dietary inclusion of Alphamune G gave better performance in broiler chicks and cockerel chicks respectively. The present study evaluated the effects of age at prelay and dietary supplementation of Alpharmune G on the performance of caged laying hens.

MATERIALS AND METHODS
One hundred and forty-four (144) commercial black Harco pullets were used for this study. The age groups were nineteen (19) and fifteen (15) weeks old tagged group A and B respectively. The pullets were weighed and randomly allotted to the four dietary groups. Each group was replicated in six battery cage compartments of three birds each. The dietary groups were the supplemental graded levels of Alphamune G (0.00, 0.04, 0.05 and 0.06%) incorporated into a basal diet (Table 1) which was formulated to meet the nutrient requirement of laying hens (NRC, 1994). Routine management programme for vaccination and other production activities in the laying hen pens followed. The birds were fed with the pre-lay diet 0-3 week and layer diet was fed 3-17 weeks of the experiment. Water and feed were given ad-libitum. Birds of group B fed with 0.00% level of Alphamune G were administered 0.05% dietary treatment level of Alphamune G at 28 weeks old till the end of the experiment. This was done to observe the effect of Alphamune G on birds not offered Alphamune G during pre-lay but later offered Alphamune G during laying. Data were collected when birds were thirty-six and thirty-two weeks old to when birds were forty-four and forty weeks old for each of groups A and B, respectively to ensure that the laying pullets are in Phase II of egg production. Feed intake and body weight gain values were measured weekly and the values obtained were employed to compute the feed to gain ratio. Feed per Dozen Egg and Feed Cost per Dozen Egg were calculated to compute the efficiency of production. Albumen height, Albumen width and Haugh unit score were recorded and used to compute the Albumen quality, Haugh unit was also calculated. A tripod spherometer was used to measure the height of the Albumen at the mid-point, Albumen width was measured with venier calliper. Nutrient retention was determined at thirty-two weeks old for a period of three days, using the total collection method. Proximate compositions of the diet and faecal samples were determined according to the methods of AOAC (1990).

Statistical Analysis
Response criteria were subjected to Analysis of Variance (ANOVA) (Steel and Torrie, 1980) for Completely Randomized experimental Design with a factorial treatment design of 2x4 (2 levels of group A and B ages of birds by 4 levels of dietary feed) using Genstat 5, Release 3.2 (2 nd Edition) Statistical software. Differences between treatment means were separated by subjecting them to Duncan Multiple Range Test (Duncan 1955).

RESULTS AND DISCUSSION
Feed intake was not significantly affected (p>0.05) dietary Alphamune R G. Laying hens fed 0.06% dietary inclusion of Alphamune R G gave the highest values for weight gain (-2.53g/bird/week) ( Table 2). This observation corroborates the reports of  when Alphamune R G was fed to broiler chicks. Cumulative weight gain is a function of nutrition; Alphamune R G and other yeast cell complex have been reported to improve feed conversion efficiency and increase final body weight in chickens Zhang et al., 2005. Body weight controls feed intake and egg size. Body weight has a dramatic effect on egg size; large birds at maturity can be expected to produce large eggs throughout their laying cycle (Leeson and Summers, 2005    There was no significant difference (p > 0.05) of interaction effect between Alphamune and Age in the egg quality traits except for Albumen height and Haugh unit. Laying hens of group A had a higher mean value of Albumen height and Haugh unit than those of group B (Table 4). Age of the hens significantly influenced (p < 0.05) the Haugh unit this observation agrees with earlier reports that many factors such as storage time, temperature, age of birds, strain, nutrition and disease may affect the Haugh unit (Atteh and Leeson, 2005;Toussant et al., 1999). Petersen (1965) reported that feed formulations or genetic manipulations may not reduce the economic loss attributed to moisture loss and a decline in interior egg quality during extended storage. In the same vein, Albumen height has been reported to decrease significantly post-storage and lower albumen weights of eggs modified by high storage temperature (Walsh et al., 1995). There was no significant difference in the egg shell thickness thus supporting the reports of Mahdavi et al. (2005) that addition of lactic acid producing bacteria to the laying hen diet had no significant effect on egg shell thickness. Bare and Striem (1998) stated that a probable explanation for thin egg shell in older hens may be lessening of calcium deposition with the passage of time. Protein and fat retention results obtained disagreed with the report of  that similar treatments did not influence nutrient retention.

CONCLUSION
Prelay supplementation of Alphamune G at 0.05-0.06% enhanced production parameters. To further ensure higher benefits from this practice, prelay dietary supplementation should be done at the age of nineteen.