"Critical Nutritional Periods In Breeding Hens And Chicks"

Unlike mammals, which continuously pass nutrients through the placenta to the developing foetus, the Budgerigar must create an egg, which contains everything that the single celled ovum needs to develop through its embryonic stage. In addition to its mineral content of 3% Calcium, 6% Phosphorus, 0.15% Sodium, 0.16% Potassium, 33 mg/kg of Manganese, 0.3 mg/kg Iodine, 0.35 mg/kg Zinc and a few less important minerals in minute quantities, the production of this egg also requires a tremendous amount of protein. Unless this supply of high quality protein is supplemented in the diet, the hen is forced to draw upon all of her available protein reserves; even that which is necessary for her own maintenance. Those who wish to breed Budgerigars cannot overlook the significance of this.

 

Research has demonstrated that control parent pairs fed only basic seed diets without supplementing, produced poorer quality, smaller, brittle feathered hatchlings in the third nest and thereafter smashed their fertile eggs prior to hatching. Control pairs from similar genetic breeding stock were able to produce and feed well grown, well feathered, vigorous fledglings for as many as 5 to 7 consecutive nests on protein supplemented diets.

 

It is also not surprising that the hens increased requirement for high quality protein supplementing and production of high quality protein crop milk corresponds with a hatchlings critical weight gain period, During the period of egg incubation, protein rich cells begin to break away from the lining of the proventriculus of the breeding hen to form crop milk. This milk on analysis, shows very high levels of protein, fatty acids, lecithin, Vitamins A and B, riboflavin, niacin, phosphorous, calcium, sodium and manganese. Unless otherwise supplemented, these nutrients are again drawn exclusively from the hens body and tissue reserves to support the growing hatchlings needs.

 

The First 28 Days

 

During the first 28 days of life, a chick's weight increases from 25 to 35 times its hatching weight of 1.2 to 1.5 grams. At this time, the forces of a developing blood system, nervous system, organ system, skin and feather system are competing within the chick for whatever protein resources are available from the crop milk and other foods offered. The overall affect of protein and amino acid deficiency during this time is sub-normal growth and development. As feather protein contains a higher amount of cystine than other body proteins, it is also during this time of maximum feather growth in a nestling that the relative requirement for cystine may also increase.

 

There are additionally some conditions that are directly related to specific amino acid deficiencies throughout these critical times. In studies of fowl, leaving out just one of the essential amino acids in the diet of a laying hen led to a decrease in her food consumption as well as an immediate decrease in egg laying. The production of keratin, which forms the nails and beaks of developing embryos, is dependent upon sufficient methionine, cysline and cysteine. Deformity of the tongue is linked to insufficient lencine, isolensine and phenylaline. A lack of tyrosine leads to thyroid hormone deficiency, which is evidenced by poor feathers, no feathers, and dark pigment melanin missing in feathers. Convulsions can be caused by inadequate amounts of pyridoxine. Incompletely formed feathers can be caused by deficiencies in arginine and glycine while food lacking arginine, methionine and glycine, from which the body synthesises creatine for normal muscle, produces poor muscle tone.

 

Of all the essential amino acids, however, lysine is maybe the single most important when it comes to growth, feather production and mortality. This is true not only during the initial growth period, but during the next critical nutritional period as the chick emerges from the nest box and begins the process of weaning. It is during this time, as a result of increased activity, continued feather growth and diminished intake of food that growth curves show a decided drop off.

 

Nearenberg et al., showed that food efficiency and body weight gain improved in 4 day old Cockatiel chicks fed 25% to 28% of their body weights per day. As the chicks grew, food intake decreased to about 15% of their body weight while food efficiency declined slightly. From 12 days to 3½ weeks when adequately fed, Cockatiel chicks reach peak body weight, there is a slight decline in food intake from 15% of body weight. As the crop capacity relative to body size decreases and passage of food into the gut is reduced there is a dramatic reduction in food intake to a level that is maintained until weaning. From the point that peak body weight occurs at 3 to 3½ weeks through weaning, when begging behaviour diminishes and less food is accepted, a number of chicks lose weight. Countering this period of diminished food intake and decreased food efficiency with an increase in the nutrient value of that food which is taken in, is extremely important.

 

In a Grau and Roudybush study designed to determine the quantitative lysine requirements of young Cockatiel chicks based primarily on growth, newly hatched chicks were fed diets in which the pure amino acids were mixed in place of protein. The lysine content of this mix was then varied from 0.1% to 2.0%.

 

Chick Growth

 

The first part of the study followed the growth of chicks from hatching to 14 days in which 0.1%, 0.4%, 1.0% and 2.O% lysine levels were given to different groups. At the end of 14 days, the mean body weight by gram and survivability were as follows :-

 

 

Of this group, the lowest level of lysine (0.1%) showed poor growth and high mortality. Not shown, but also significant, was the fact that feather growth of the survivors was poor. As the level of lysine was raised in the other groups, survivability was good and weight gain was progressively better up to 1.0%. Then there was a decline in weight of the 2.0% group. This was an initial indicator that 2.0% lysine was above the optimal level for growth.

 

The second part of this study followed groups of chick's growth rates on 0.2%, 0.4%, 0.6%, 0.8% and 1.2% lysine diets. The following table depicts mean body weight and survivability of each of these groups at day 28.

 

 

Again, at the lowest level (0.2%), weight gain was slow and survivability poor. This group also showed poor feather growth. At moderate levels of lysine (0.4% to 0.6%) survivability jumped dramatically, as did weight gain. Feather growth did occur. At 0.8% the maximum growth and maximum survivability was attained. The drop off at 1.2% lysine, indicates, again, that this level is beyond the optimum. Based on this and the results of the first part of the study, it appears that the optimal level of lysine in a Cockatiel chicks diet falls somewhere between 0.8% and 1.1%.

 

One other aspect of this study should be pointed out. Lysine deficiency effects the melanin formation in feathers of turkeys, chickens and quail, yet regardless of the level given to Cockatiels, melanin formation was not affected. While it is true that comparative studies of whole carcass amino acid composition of the chicken to the Budgerigar shows a similarity which may allow the use of some broiler requirements for growth, this is an excellent example of why it is difficult to rely on poultry nutrient requirements with any degree of confidence.

 

Other Critical Periods Requiring Protein Supplementing

 

There are other periods or times during the adult life cycle that supplementary protein feeding is important. The first is during and immediately following illness, when body weight has substantially dropped and energy demands, disease process and medications have depleted the bird's nutrient base. The second is during a moult. Feathers are composed of protein and just like the chicks; forces within the adult are competing for protein reserves available during new feather growth. The third is an environmentally related factor concerning seasonal changes. During periods of hot weather, when there is a corresponding decrease in food consumption as energy requirements are diminished, what food is eaten needs to be packed with nutrients.

 

 

 

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Edited April 3, 200916 yr by Daz

wow. very in depth stuff there.. Great read again daz. Thanks very much for posting all these articles they are great, Although I don't know if I would breed my birds for

 

as many as 5 to 7 consecutive nests

Some of the uk breeders breed their birds for 5+ nests in a row. How they do it I dont know.