The effect of methionine, lysine and/or vitamin C (ascorbic acid) supplementation on egg production and egg quality characteristics of layers in the humid tropics

K U Amaefule,  G S Ojewola and E C Uchegbu

College of Animal Science and Animal Health, Michael Okpara University of Agriculture,
Umudike, PMB 7267 Umuahia, Abia State, Nigeria.
amakelvin@yahoo.com

Abstract

 

One hundred and sixty-eight Bovan Nera layers (average 1.98 kg) that had been in lay for 10 months were used to evaluate the effect of methionine, lysine and/ or vitamin C (Ascorbic acid) supplementation on egg production, external and internal egg quality characteristics of layers in the Humid Tropics. The experiment, which was in a completely randomized design (CRD), had seven treatments each replicated three times. There were 8 layers per replicate. The experimental diet was a 16% CP and 11.68 MJ kg^-1 layer mash supplemented with either 0.03% vitamin C (VitC), 0.1% methionine (Me), 0.1% lysine (Li), 0.1% methionine + 0.03% vitamin C (ViC-Me), 0.1% lysine + 0.03% vitamin C (VitC-Li) or 0.1% methionine + 0.1% lysine (Mi-Li).  The control diet (Ctl) had no methionine, lysine and/ or vitamin C supplementation.

The study lasted 5 months (November - March). Results showed that the supplementation of the layer diets with methionine, lysine and/ or vitamin C did not significantly  influence egg production, external and internal egg quality characteristics of the layers.

Therefore, it may not be advantageous to supplement the diet of old layers with methionine, lysine and/ or vitamin C.

Keywords: Ascorbic acid, layers, lysine, methionine, supplementation.

 

Introduction

 

The levels and balance of amino acids in the diets are all important nutritional variables that affect the economic efficiency of an egg laying enterprise (Al-Saffar and Rose 2002a). Lysine, methionine, methionine plus cystine and tryptophan are the major amino acids that can be limiting in practical feeds for laying hens (Olomu 1995). It has been reported that supplemental methionine and/ or increase in dietary protein did not affect early egg size of birds (Summers et al 1988) and that higher levels of dietary protein resulted in small increases in egg production and egg weight (Proudfoot et al 1988). Scott and Balnave (1988) indicated that laying hens subjected to heat stress couldn't meet their nutrient requirements especially for essential amino acids regardless of increased nutrient concentration of the diets. They demonstrated that hens fed protein and energy on a free-choice basis had higher levels of protein intake than conventionally fed ones and were able to significantly increase egg size in a hot environment. Summers et al (1991) have shown that the supplementation of a low protein (10% CP) diet with 0.32% DL-methionine resulted in a 10% increase in egg mass. Lysine supplementation of a methionine-supplemented 10% CP diet further increased egg mass output by 26%.

 

Poultry are renal synthesizers of ascorbic acid (Roy and Guha 1958), which is not therefore normally included in poultry diets. Despite this, vitamin C synthesis is thought to be inadequate during times of heat stress, disease and intensive production (Coates 1984; Horning et al 1984). Vitamin C has equally been reported to be important in the management of heat stress by chicken in the Tropics (Pardue and Thaxton 1986; Brake 1989; Njoku and Nwazota 1989; Tuleun and Njoku 2000). Research efforts mostly in the Temperate countries have focused mainly on the maximization of egg numbers, egg size and quality; however, there is the need to establish ways of maintaining egg production, egg size and quality throughout the laying period and during periods of heat stress in the Humid Tropics. This study was therefore designed to evaluate the effect of methionine, lysine and/ or vitamin (Ascorbic acid) supplementation on egg production and egg quality characteristics of layers in the Humid Tropics during the hot period of the year.

 

Materials and methods

 

Diets

 

Seven isoenergetic and isonitrogenous diets were formulated and each contained 16.1% CP, 11.7 MJ kg^-1 ME, 3.32% Ca and 0.60% P.  The arrangement of the supplementation was: 0.03% vitamin C (VitC), 0.1% methionine (Me), 0.1% lysine (Li), 0.1% methionine + 0.03% vitamin C (ViC-Me), 0.1% lysine + 0.03% vitamin C (VitC-Li) or 0.1% methionine + 0.1% lysine (Mi-Li).  The control diet (Ctl) had no methionine, lysine and/ or vitamin C supplementation.
 

Birds and their Management

 

One hundred and sixty-eight black Bovan Nera layers that had been in egg lay for 10 months were used for the study which was conducted during the hot months (November - March) of the year. They had an average liveweight of 1.98 kg at the beginning of the experiment. The layers were housed in a 2-tier battery cage located in an open-sided poultry house covered with wire gauze but roofed with corrugated iron sheets. The battery cages were equipped with open (manual) feeder troughs and nipple drinkers. Water supply to the nipple drinkers was from an over-head 500 litre water tank. Each cage cell (60 cm x 42 cm x 40 cm) contained two layers. The ambient temperature of the experimental poultry house measured with a thermometer hung above the cages ranged between 23 and 25^oC (average 24^oC) throughout the period of the experiment. The layers were vaccinated against Newcastle (I/O, Lasota, Kamorov), Gumboro and fowl pox diseases during the rearing period. The feeder troughs were demarcated with flat aluminum sheets to prevent feed from one replicate or treatment mixing with another and this also prevented birds from one replicate feeding from another.

 

Experimental Design and Data Collection

 

The experimental design was completely randomized (CRD). Each treatment had three replicates and each replicate was allotted 8 birds. The feed allowance for each layer was 125 g d^-1 as recommended by Obioha (1992). Water was provided ad libitum. The birds were fed two times a day; in the morning (8.00 - 8.30 am) and in the afternoon (2.00 - 2.30 pm). Egg collection was two times daily, in the morning (9.30 - 10.00 am) and evening (4.30 - 5.00 pm). The birds were weighed at the beginning of the experiment and subsequently at two weekly intervals. The number of eggs laid by birds in each replicate were recorded daily and summed up at the end of the month to obtain monthly egg production. Percent hen-day production was calculated as number of eggs laid divided by the number of hens multiplied by the number of days according to the procedure of Oluyemi and Roberts (1979). Feed conversion ratio (FCR) was calculated as feed consumed divided by egg weight.

 

Egg Quality Determination

 

Eggs from each replicate were sampled for quality characteristics three times a month. All eggs laid by birds in each replicate were weighed individually on the day of sampling using an Aculab electronic (sensitivity 0.01g) top-loading scale. Egg length and diameter were measured with a Venier Caliper and egg shape index calculated as egg diameter divided by the length. Eggshell thickness was measured with an Ames micrometer screw gauge (Ames 25 M5). After cutting the eggs open to obtain yolk and albumen, the eggshells were carefully washed with water to remove adhering albumen, dried at room temperature and weighed to obtain eggshell weight. Yolk diameter was determined with a Venier caliper, while yolk and albumen heights were measured using Ames Tripod Thickness measure (Ames S-6428, 0.1mm). Yolk index was calculated as yolk diameter/ yolk height while Haugh unit was determined using USDA Interior Egg Quality measure (USDA Chart for scoring broken-out eggs, Catalog 4-4200 American Instrument Co. Inc. Silver Spring, MD). Yolk was separated from albumen with a separating spoon and each weighed with an Aculab electronic scale.

 

Data Analysis

 

Hen-day egg production, egg weight, final live weight and data on external and internal egg quality characteristics were subjected to analysis of variance (ANOVA) as outlined by Steel and Torrie (1980).

 

Results and discussion

 

The supplementation of the diets with methionine, lysine and / or vitamin C, or combinations of these nutrients, did not affect any of the production parameters considered (Table 1) nor the external egg quality characteristics (Table 2).
 

Vitamin C supplementation did not influence egg production and egg weight probably due to the fact that the ambient temperature of the poultry house during the period of the experiment was below 28^oC which is the temperature at which panting and the acute effects of heat stress are expected to occur (Al-Saffar and Rose 2002b). The results obtained agree with those of Creel et al (2001) that there is no beneficial reproductive response to the inclusion of ascorbic acid in commercial broiler breeder diets.

 

Although the egg shape index and shell weight values were within the range reported by Olorede and Longe (2000), they were numerically lower than that reported by Adeyemi and Adeyemi (2000). This may be due to the fact that egg shell thickness and shell weight reduces with increase in egg size (Roland 1980; Jackson et al 1987) and age of hens in lay (Jackson et al 1987; Harms et al 1990). The ambient temperatures during the period of the study, which were higher than 21^oC, may also have contributed to the low egg shell thickness and weight. Internal egg quality characteristics showed the same trend with the external egg quality measurements (Table 3).
 

 

Conclusion

 

Supplemental methionine, lysine and/ or vitamin C (Ascorbic acid) had no significant effect on egg production and egg quality characteristics of old layers in the study region in the humid tropical region of Nigeria.

 

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