Austerity Diet & Feeding for Breeding
Austerity DietFor passerines that are indigenous to tropical and arid regions, the periodic availability of food and water is even more important to the reproductive cycle than seasonal changes in daylight hours.7 Most successful breeders of these species use a method called the austerity diet to mimic these natural dietary conditions and thereby stimulate breeding. During the hot season (summer) after breeding has ceased for the year, reduce the protein, fat, and caloric content of the feed.2,7 Because birds consume less food in hot weather, they will probably need higher concentrations of certain nutrients, particularly vitamin A, in their feed.2 Allowing vegetable matter to provide the bulk of the food intake will meet these requirements,2 and the finches' physical condition can be maximized by allowing them to have free flight in spacious aviaries.7 To signal the beginning of the breeding season in the fall, provide a "flush" diet to encourage the finches to come into breeding condition.2,7 The flush diet increases the plane of nutrition7 by providing a higher volume and quality of feed,2 including increased caloric, fat, and protein content. Providing plenty of green, fresh foods may help stimulate breeding in desert-dwelling species such as the Australian grass finches.7 This seasonal change in diet can be arranged so that the flush diet correlates with the molt, allowing birds to have the nutrients they need in order to molt successfully.2
Feeding For BreedingMany people wonder how to take care of their birds when they are expecting eggs or young in the nest. In fact, one of the most common questions I am asked is, "What should I feed a baby finch?" In most cases, you will not need to feed any babies directly, but rather provide the parents with a nutrient rich diet that is adequate for rearing their young. However, in order to breed birds successfully, good nutrition must be provided weeks before the first egg is ever laid.
A hen requires an adequate diet to allow her to meet the stresses that reproduction places on her body. The degree of this reproductive stress is directly related to how many eggs she lays.6 In many species, a small number of eggs is laid and the nutrients required to produce them are taken from body stores.6 However, reproduction and hatchability will suffer if supplementation is not provided and body stores of vitamins become depleted.6 Each egg produced consists mostly of fat, protein, and calcium--the three nutrients that represent the largest increase in dietary demand during production.5 Therefore, in order for a hen to lay healthy eggs, higher levels of protein (particularly the sulfur amino acids and lysine) as well as higher levels of calcium are required in the diet.5 Providing calcium is important for minimizing the decalcification of bones as well as for preventing soft shelled eggs from forming5 (normal shell thickness and conductance will both deteriorate if a hen has a calcium deficiency).6 The hen will eat enough food to meet her energy (fat) demands, so you probably will not need to increase the fat content of the diet.5
In addition to amino acids, energy, and calcium, other nutrients (namely vitamins and minerals) are also required for healthy egg production. Together, these nutrients meet all of the embryo's needs for normal cell division, growth, and maturation.5 However, if a diet which allows for production is still deficient in any of these nutrients, embryo development may be abnormally affected5 or even ceased. Un-supplemented seed diets fed to hens which are experiencing vitamin deficiency often result in eggs that develop to a point but never hatch due to early embryonic death.5,6 Different deficiencies are responsible for embryonic death at different stages of development. If a blood ring forms after approximately 3 days of development, but further growth ceases, the embryo's death was most likely due to vitamin A deficiency.5 If a chick was too weak to complete the hatching process, resulting in death immediately prior to hatch, a deficiency in one or more of the following nutrients is likely: biotin, folic acid, riboflavin, and vitamin B12.5 Finally, if an embryo dies due to malformation, suspect a zinc and/or manganese deficiency.5
If a nutrient-adequate diet was fed to a healthy, producing hen, fertilized eggs that do not experience any other problems (such as contamination, improper incubation, or breakage) will hatch. Shortly prior to hatch, the remaining portion of the yolk sac is absorbed into the abdominal cavity of the embryo.5 For the hatchling, this yolk sac acts as a temporary energy reservoir which may adequately supply nutrients for the first 1-3 days of life (depending on the species).5 Once the yolk is depleted, the chick must be fed an adequate diet by the parents in order to survive and grow. Because growth places such a heavy demand on the chick, nutrient requirements are now at the highest point they will ever be during the bird's normal life.5 The period of rapid growth demands linoleic acid, amino acids, energy, vitamins, and minerals in levels which exceed adult maintenance requirements.6 The diet fed to chicks, therefore, must be formulated to meet the chicks' growth requirements and not the requirements of the parents.5,6 Nutrition during chick rearing is important for the health of the chicks, not their parents.6
In fact, the main reason for dramatically increasing the plane of nutrition given to the parents during breeding is to provide them with an adequate diet to feed their young.5 In addition to meeting the requirements for chick growth, other benefits should result from providing such a rich diet during breeding. For instance, proper daily feeding for optimal chick growth will decrease the duration of the chicks in the nest.5 Additionally, a moderately high plane of nutrition should optimize the parents' body stores by allowing for the ready repletion of depleted stores.5 This, in turn, promotes the rapid recycling of the hen through preparing her physiologically for laying a second clutch.5
As altricial birds, parent finches consume food and water which is stored in their crops until it is regurgitated for their chicks. This food must contain the correct proportions of each required nutrient if the chicks are to grow efficiently and to their maximum potential.6 While stored in the crop, the food settles into stratified layers with the highest water content present in the top layers.6 The behavioral adaptation (witnessed in budgies,6 but likely also applicable to finches) of feeding the chicks in order from youngest to oldest allows for the youngest chicks to receive the highest proportions of water as they are fed from the top most layers in the crop. This presumably ensures that the chicks who need the most water in their diet receive it, as younger chicks have a higher water requirement than older chicks.6
Through their begging behaviors, chicks stimulate their parents to retrieve and deliver food back to the nest.6 According to observations made during experiments with breeding cockatiels, begging behavior may be one indicator of the adequacy of the diet for chicks.6 Chicks who did not receive enough protein in their diet (only 10-15%) begged more vigorously and more often than chicks that received adequate amounts of dietary protein (20%).6 Those chicks who were over-fed protein (35%), on the other hand, rejected feedings and even regurgitated some of their food.6 This shows that chicks who receive adequate amounts of a nutritionally balanced diet will remain peaceful most of the time, and only beg infrequently, whereas malnourished chicks will beg more or reject feeding if they are under or over nourished, respectively. Of course other factors may contribute to feeding rejection, including disease, environmental change, temperature of the diet, the natural shrinkage of the crop that occurs when the chick reaches peak body weight, or simply because of the weaning process.6
In conclusion, here are some feeding tips for when you are expecting eggs or young in the nest:
- Preferably starting before any eggs are laid, feed the parents-to-be a high quality egg mix or appropriate, nutrient-rich soft food. Also, provide a variety of fresh fruits and vegetables daily while breeding. Continue providing these supplements daily after the chicks hatch to act as a nestling food.
- Have a calcium source (such as cuttle bone, cooked and mashed eggshell, or ground-up oyster shell) available at all times.
- For insect eating birds (some of which require insects as a substantial [30-60%] portion of their diet), a high quality puppy food soaked in water and then mixed with a good vitamin and mineral supplement is recommended as a base diet.7 Some species may not breed successfully unless provided with live insects or an insect mix in large quantities which are refilled multiple times per day.