CONCEPT OF ECONOMIC FEED FORMULATION FOR COMMERCIAL LAYERS- PART-1

Feed formulation is the process of quantifying the amounts of feed ingredients that need to be combined to form a single uniform mixture (diet) for poultry that supplies all of their nutrient requirements. Since feed accounts for 65-75% of total live production costs for most types of poultry throughout the world, a simple mistake in diet formulation can be extremely expensive for a poultry producer.

Feed formulation requires thorough understanding of the:

• Nutrient requirements of the class of poultry (e.g., egg layers, meat chickens or breeders).
• Feed ingredients in terms of nutrient composition and constraints in terms of nutrition and processing.
• The cost and availability of the ingredients.

Most large-scale poultry farmers have their own nutritionists and feed mills, whereas small operations usually depend on consultant nutritionists and commercial feed mills for their feeds. It is therefore essential that formulations are accurate because once feeds are formulated and manufactured, it is often too late to remedy any mistakes or inaccuracies without incurring significant expenses.

PRINCIPLES OF FEEDING:  Nutrition and feeding in the early part of life do not have an influence on subsequent laying performance. Fast growth is also not the criteria in rearing replacement pullet. The major objective is to raise them at good health to attain sexual maturity at a given weight depending upon genetic make up of the birds with minimum nutritional input. Modern layers, however, rich to the sexual maturity i.e. the point of lay at little earlier age than ever before, as a result the birds have been able to produce 310-325 eggs per year.

Besides nutrition, the other factors that influence the age of sexual maturity include the season of the hatch, duration of light days, light stimulation, overall management and stress, and diseases. Light plays an important role in age at sexual maturity. Decreasing duration of day light delays sexual maturity. A low protein and/or low energy diet, or quantitative restriction of a balanced feed also delays sexual maturity. Larger egg size is obtained from delayed sexually matured birds. Reaching to sexual maturity at an earlier age is always associated with the smaller size of eggs.

GROWTH PHASES OF EGG TYPE PULLETS:   The laying may be typed as laying hens for production of table eggs (for consumption of human being) and laying hens for production of settable eggs (for hatching). The former type is called layers and the second type is called as breeders. The body weight and nutrient requirements are almost similar for both the groups except certain micronutrients, which are given in excess in breeders diet. The replacement pullets are generally reared in three phases starter (0-8 weeks of age), grower (8-20weeks of age) and layer (20 weeks or above). In certain countries a five phases feeding system has been recommended i. e. Starter (0-6weeks of age), Grower-I (6-12weeks of age), Grower-II (12-18weeks of age), Grower-III (18-to 1st egg) and layer (20weeks or above).

PRODUCTION PHASES OF LAYER: The layers are fed in phases, generally three (phase I 18-35 wk of age, phase II (35wk – 50wk) and phase III (50wk and above) but laying period can be divided into more phases depending upon the age for economic feeding of layer. 

• Phase I is characterized by an increase in body weight to achieve mature body weight, increase in egg size and increase in egg number.
• Phase II is characterized by an increase in egg size and maintaining peak egg production and body weight achieved in phase 1. 
• Phase III egg size is increased but egg production and body weight are decreased. Thus, the requirements of protein and energy alter.

ECONOMIC FEED FORMULATION: Economic feed formulation requires attention in precise nutrient supply (nutrient supply matching the requirements), the inclusion of locally available low-cost feedstuffs in feed formulation and use of effective supplements and feed additives for improved utilization of feed.

NUTRIENT REQUIREMENTS: The requirements of energy and protein are much lower than the broilers. The raising system also one of the determinants of dietary energy concentration. The layers reared in cages require less energy than those on litter, as the movement is restricted in cages, thus saving energy. Similarly, the growth is more in the starting phase and then decreased in the growing phase, and thus requirements of energy and proteins are decreased with age up to a growing phase. Thereafter, again increased slightly in laying phase. The energy concentration ranges from 2650 to 2850 kcal/kg during starting, 2600-2900kcal/kg during growing and 2500 to 2800 kcal/kg diet during laying phases. Similarly the requirements of protein for the corresponding phases are 18-20%,15 to 16% and 15 to 18%. The requirements of nutrients specified by NRC, BIS and Degussa are given in Table 1 to 5. NRC (1994) recommendations provide much energy (2800-2900kcal ME/kg). It becomes difficult to provide such amount of energy under Indian condition, thus the dietary energy level is kept in between 2500to 2700 kcal ME/kg during the growth period. 

Moreover, being a tropical country the maintenance requirement is slightly lower. The lower energy level in the diet is associated with more feed consumption per unit gain or egg production (higher feed conversion ratio). In laying hens the dietary energy concentration ranges from 2550 to 2700 kcal ME/kg. On an average one laying hen producing 90% egg requires 16-18gram of protein and 285 to 290 kcal ME per day. The protein and amino acid profile in the diet is important for optimum growth, feed conversion, egg size, and egg production. Meeting calcium requirement is important during overall growth (0.9 to 0.7%) and laying phases, but most crucial during the laying phase. The requirement of calcium for commercial layers is increased much (4.0 to 4.5g/bird/ day) in the diet. Just prior to the initiation of egg production, a huge amount of calcium is stored in bones, which is sufficient for 6 to 30 eggs. Therefore, calcium concentration is increased to about 2% of diet a week before onset of egg production. Once egg laying is started the birds adjust calcium requirements from dietary intake and also drawing from body reserve. The specific gravity of eggshell is increased with increased calcium concentration in diets.

The White Leghorn hens producing 90% egg require about 4.5 g of calcium daily. The half of the calcium in the diet should be supplied through coarsely ground powder and remaining half as grit so that the needy hens may select and consume calcium as per need and palatability of feed is maintained. Therefore, in addition of dietary calcium (3 to 3.5%), there should be continuous excess to shell grit to the birds. Shell grits improve digestion and utilization of other nutrients also by helping in grinding of feed materials in the gizzard. Addition of grit of appropriate sizes in mash at an interval of every two to four weeks may be beneficial. The retention of calcium during the first 40 weeks is about 55% and decreased thereafter with age. Thus, the requirement of calcium is increased with age. Heavy birds consume more feed, thus a dietary concentration of calcium should be lesser. Any factor that affects feed intake like ME content of the diet, environmental temperature, etc. will affect calcium concentration in diets. The available Protein requirements are 0.4% in starting, 0.35% during growing and 0.28 to 0.35% during laying phase (300 to 350mg/ day/layer).

The Egg-laying hen needs nutrients for :
1. Body maintenance
2. Early in the lay cycle growth
3. Egg production

An overabundance of nutrients will lead to increased bird growth along with increased egg size.

• The level of nutrients in the feed (% protein, % specific amino acids, Metabolizable Energy (kcal/ kg), % calcium, % oil/fat, etc.)
• The amount of feed intake in a 100 g/bird/day feed consumption of a ration with 19% protein, 0.45% methionine, 2850 ME kcal/kg and 4 % calcium means the birds are getting daily the 19 g protein, 0.45g methionine, 285 kcal and 4 g calcium needed for production of a large size egg.

to be continued… On Part