Varying levels of dietary crude proteins and balanced amino acids were fed to layers for a period of eight weeks starting from the twenty-sixth week of age of birds and six weeks into egg production. Effects on performance and haematological characteristics were investigated at this second phase of production. Sixty Black Nera hens were randomly allotted into four (4) dietary treatments, containing the following levels of crude protein 14%, 15%, 16%, 17% and the metabolizable energy was iso-caloric for each treatment. The results showed that there were no significant differences (P > 0.05) observed for lymphocyte, Haemoglobin (Hb), Packed Cell Volume (PCV), Red Blood Cell (RBC) and White Blood Cell (WBC), these haematological parameters were within the range for healthy birds. Thus crude protein level of 14% can be used in diets of layers at the second phase of production provided that adequate amino acids are given, without adverse effect on egg laying, feed intake and measured blood parameters.
Poultry production is aimed at the massive production of meat and eggs for the teeming world population. The livestock industry in Nigeria had been appraised for its substantial contribution to the national wealth and for supplying the populace with important animal protein required for health and body maintenance [
Egg production in a poultry flock follows a pattern, this pattern is similar for most breeds of chickens, the specific numbers can vary significantly, especially with regards to age at first egg, peak production rate and egg weight. Egg production typically begins when the pullets reach 18 to 22 weeks of age, depending on the breed and season. Egg production, as a percent of hens housed, rises sharply till it reaches its peak about 6 - 8 weeks later. Peak production levels of 90% or higher are common with some of the egg-laying breeds (such as Leghorns), after which production gradually declines until it descends to a level where the hens are consuming more money in feed than is produced in eggs. At this point the flock is either terminated or put through a molt to start a second laying cycle [
With feed costs often representing about 70 percent of the production cost of a dozen eggs, feed costs per dozen eggs must always be the least-cost against expected egg revenue in order to maximize profits. Any savings in feed consumption will usually translate into increased profit margins. Several management factors can be implemented which will result in feed savings and added profits [
A total of sixty Black Nera layers in their second phase of production were used in this experiment. They were randomly allotted to four treatments with five replicates in a completely randomized design. All the birds were individually weighed at the onset of the study and consequently every 4 weeks till the conclusion of the experiment. Growth and productive performance criteria were evaluated as final weight (FW), weight gain (WG), feed intake (FI), feed conversion ratio (FCR) and Henday production were determined.
The experimental diets presented in
Blood was collected from three birds per replicate at the end of the study period. 5 mls of blood was collected from the birds with the aid of sterile syringes via the jugular vein. The blood samples were in two (2) sets per replicate that is test tube devoid of anti-coagulant (EDTA) and sera were subsequently extracted from this through centrifugation for serum analysis. The second sets which contained 1 ml of blood were collected into test tubes which already contained ethylene diamine tetra-acetic acid (EDTA). The blood sample was kept in fresh state
(refrigerator) by this anti-coagulant to make possible hematological studies. The samples were analysed for Packed Cell Volume (PCV), Haemoglobin (Hb), White Blood Cell (WBC), and Red Blood Cell (RBC) counts.
The ethical standard for handling of live animals was followed as set by Nigerian Institute of Animal Science (NIAS).
The data obtained were subjected to the statistical analysis using one way analysis of variance. The data were subjected to Duncan’s multiple range test as described by [
There were no significant differences (P > 0.05) observed for final weight, weight gain, feed intake and egg production. It was however observed that Diets 2 (−0.024 kg) and 4 (−0.073 kg) had negative weight change as presented in
*Premix supplied per kg of diet: Vit A, 10,000 IU; Vit D, 2800 IU; Vit E, 35,000 IU; Vit K, 1900 mg; Vit B12 19 mg; Riboflavin, 7000 mg; Pyridoxine, 3800 mg; Thiamine, 2200 mg; DPantothenic acid, 11,000 mg; Nicotinic acid, 45,000 mg; Folic acid, 1400 mg; Biotin, 113 mg; Cu, 8000 mg; Mn, 64,000 mg; Zn, 40,000 mg Fe, 32,000 mg; Se, 160 mg; Iodine, 800 mg; Cobalt, 400 mg; Choline, 475,000 mg; Methionine, 50,000 mg; BHT, 5000 mg; Spiramycin, 5000 mg.
Results presented in
The research carried out by the department of Animal and Poultry Sciences at Virginia Tech, USA published in Zootecnica [
Mean in the same row with different superscripts are significantly different (P < 0.05).
Means in the same row with different superscripts are significantly different (P < 0.05).
PCV—Packed Cell Volume HETERO—Heterophils RBC—Red Blood Cell EOSI—Eosinophils WBC—White Blood Cell Hb—Haemoglobin LYMPH—Lymphocyte MONO—Monophils amino acid mainly methionine and lysine, usually support adequate weight gain. [
This study revealed that increasing crude protein in layer diets resulted in increased feed intake and egg production. The reduced production observed on lowered crude protein values which occurred despite amino acid supplementation, suggests that limiting amino acids may not have been added back in sufficient quantities and that maintaining the minimum level of crude protein was beneficial. However, diets which had CP just below the minimum recommendation (a reduction of approximately one percentage point) were able to maintain hen day performance.