LPM 222: Diversified poultry production and current concepts in poultry management and marketing [Livestock Production Management (Regional Interest)] (1+1)

OSTRICH BREEDER MANAGEMENT

Breeding behaviour in wild

• Breeding groups in the wild commonly include one territorial adult male per 3 to 4 females, at least one of which is a “major” female mated to the territorial male in a monogomous bond.
• Most breeding occurs in the dry season, allowing the chicks to hatch before heavy rains begin. The nest site is selected and begun by the territorial male some time before mating. The major female accepts the site, may enlarge the nest, lays her eggs, and incubates her eggs and those laid by “minor” females in the same nest. Wild major females lay (on alternate days) a clutch averaging 8 eggs (range 5 to 11).
• Minor females lay an average of 3.7 eggs per clutch (range 2 to 6). Usually 2 to 5 minor females lay in the nest of the major female by visiting the nest only briefly.
• The number of eggs that a major female can incubate is about 19-25. Thus, the major female’s own clutch constitutes less than half of the total.
• Eggs exceeding the number that can be incubated are ejected and form a ring surrounding the nest. Since major females recognize their own eggs, the ejected eggs are mostly those of minor females.

Fig. 7.23. Ostrich nest (note the ejected eggs on the periphery)

Egg production under farm conditions

• Breeding season length largely depends on food availability, bird condition, and weather. Approximately two months prior to the beginning of the breeding season, birds should be separated into breeding pairs. Groups of one male and two female birds can also be penned together.
• Bird condition is important as unhealthy and improperly conditioned birds will often be less productive egg layers. Courtship of ostriches involves elaborate displays by both sexes.
• Shortly after mating, the female will lay between 15 to 20 eggs. Generally, females will lay an egg every alternate day. If the eggs are taken from the nest daily, the hen may lay 40 to 50 eggs. However, some highly productive females can lay up to 90 eggs in a season. Ostrich eggs are the largest of all eggs and weigh about 1.5 kilograms. The content of one ostrich egg is equivalent to two dozen chicken eggs.

Egg Collection

• For commercial ostrich farming, it is important that all eggs are removed from the nest at least twice daily. On the other hand if allowed to incubate, the female will stop laying until the chicks have reached four to five weeks of age, resulting in financial loss.

Sex Ratio

• The breeding ratio of cocks to hens of 1:1 or 1:2 results in an overall good fertility. When all the breeders are in optimal breeding condition, the use of male - female ratios of 1:3 (quads) significantly reduce production cost at no adverse effect on fertility. Naturally, the male ostrich is polygamous, usually having one major hen and two or more minor ones.
• Male ostrich copulates up to three times a day. Ostrich hens have sperm storage glands in their reproductive tract and not need to mate frequently to maintain fertility. These sperm-storage tubules are located at the utero-vaginal junction of the oviduct and have a fertile period upto 28 days post-coitus .

Factors Affecting Fertility

• Infertility can be broadly classified into hen infertility, mainly involving failure to lay eggs (barrenness) and cock infertility, involving the inability to supply viable spermatozoa and subsequently the production of candle-clear eggs.

i) Cock Infertility

• Cock fertility is influenced by age, stage of breeding season, frequency of ejaculation, sperm supply, disease and nutrition.
• Male ostriches mature sexually at about 36 months of age. Attempts to breed the male ostrich before it attains sexual maturity can lead to the production of infertile eggs since semen of juvenile male ostriches are devoid of viable spermatozoa.
• Seasonal infertility may occur, when hens produce eggs early in the season before cocks are able to produce functional spermatozoa, or when hens continue laying eggs at the end of the breeding season.
• The ostrich testicle goes through four cycles, namely the active (September-January), regressive (February-March), quiescent (April-June) and recrudescent (July and August) in the Southern hemisphere. The respective periods in Northern Hemisphere is April –August (active), September and October (regressive), November – January (quiescent) and February and March (recrudescent).

ii) Hen Infertility

• Hen fertility is influenced by reproductive age, feed energy levels, diseases and efficiency in sperm storage.
• Egg production per hen per year is an important parameter to estimate reproductive performance in breeding farmed ostriches. The female ostrich matures sexually at about 24 months of age, after which it starts laying eggs, undergoing varying stages of ovarian activity. It remains fertile for about 40 years, during which period annual egg production varies between 20 and 70 eggs.
• The ostrich hen is an opportunistic, indeterminate breeder, laying an egg every other day in late afternoon during the breeding season and will continue to lay eggs for long as the eggs are removed from the nest. However, to preserve their vigour, the breeding season is usually restricted to only 6-8 months in a year.
• The development of the ovarian follicles and reproductive health status in the female ostrich can be detected and monitored by ultrasonography.
• Ultrasonography could also play a big role in breeder selection, in discriminating between ovulating and non-ovulating hens and in quantifying the egg production potential of individual hens at the start of the season, considering that characteristics like egg production are satisfactorily repeatable and predictable.
• Hen infertility can also be a result of females that retain too few sperms after mating, or that retain sperms for a shorter time in their sperm storage tubules.
• Many diseases may result in reproductive failure, either through failure to produce eggs or through production of abnormal or contaminated eggs.
• Chronic diseases such as aspergillosis or avian tuberculosis may cause reduced fertility before clinical signs become noticeable. Internal parasites may result in debility directly or via a decrease in the availability of essential nutrients to the bird. External parasites may cause irritation, general disturbance and sometimes blood loss.
• Average egg production, fertility and hatchability are also compromised when stocking rate is high in ostriches.

iii) Nutritional Causes of Infertility

• Feeds containing energy levels lower that 2000 Kcal ME/ kg can affect body condition of breeders and can decrease egg production. Overfeeding of breeders can lead to obesity, which condition is associated with a decrease in libido.
• The recommended feeding rate of ostriches during the breeding season is 2 kg /bird/day of breeder ration, translating to 4600 Kcal ME of energy and 320 g protein daily.
• Ostriches should be pre­conditioned 4 weeks prior to the commencement of the breeding season in order to get them back into active breeding following the off season, when they are fed a maintenance ration that is lower in almost all nutrient levels.
• Vitamin A and E deficiencies have often been associated with infertility. Vitamin A is important in the maintenance of epithelia, including testicular epithelium. Among minerals, selenium is important for fertility.

Factors Affecting Hatchability

• Hatchability denotes the percentage of fertile eggs that hatch successfully following an appropriate incubation period, which is about 42 days in the ostrich at 36.3°C and 25 to 40% relative humidity. Hatchability therefore, basically involves losses owing to embryonic death at various stages of development.

i) Incubation Temperature

• The optimum incubation temperature for ostrich eggs is 36.3°C. Higher incidences of dead-in-shell embryos and total number of dead embryos are noted when eggs are incubated at 37.5°C.
• Towards the end of incubation, the temperature inside the egg rises by 2.0°C above the surrounding air temperature, as a result of metabolic heat production by the embryo. This may result in the death of the embryos due to hyperthermia, when the same incubation temperatures are maintained throughout incubation. Therefore, incubation temperatures should be slightly reduced during last 3 days of incubation.

ii) Relative Humidity

• The relative humidity for incubation of ostrich eggs is considered to be 25 to 40%. This humidity enables incubating eggs to lose between 13 and 15% of their original weight in the form of moisture and is an important determinant of hatchability in ostriches.

iii) Egg Shell Properties

• It plays an important role in determining hatchability. During development, oxygen, carbon dioxide and water vapour are transported in to and out of the egg through pores in the egg shell.
• The ability of the ostrich egg to lose moisture therefore, depends on parameters like shell porosity and shell thickness. Ostrich eggs that possess low porosity and increased thickness hatch poorly.

iv) Egg Weight

• It has also been shown to influence hatchability, with large eggs having problems losing the required amount of water resulting in oedematous chicks.
• Excessive moisture loss of above 18 % at 35^th day of incubation results in hatching out dehydrated weak chicks, which may at higher risk of dying before they attain the age of 28 days.

v) Egg Contamination

• Egg contamination can be lethal to the embryo even at low doses. Microbial contamination of eggs can result from the dipping or washing of eggs in liquid disinfectants before setting them into incubators that possibly leads to the disruption of the protective cuticle of the egg shell. As a result, fumigation should be routinely carried out before setting eggs in to the incubator in order to avoid egg washing.
• Various bacteria (Escherichia coli, Aeromonas sp., Enterobacter sp., Acinetobacter sp., Citrobacter sp., Streptococcus faecalis, Klebsiella sp., Staphylococci sp., Bacillus licheniformis and Achromobacter sp.) and fungi (Penicillium sp. and Fusarium sp.) are associated with ostrich egg contamination.

vi) Pre-incubation Storage

• Prolonged pre-incubation storage of over 10 days affects hatchability. The eggs should never be stored more than 14 weeks.

vii) Stocking Density

• High stocking density has negative effect on hatchability.

viii) Breeder Age as measured from the first season of breeding, as well as breeding season also affects hatchability.

ix) Nutrition

• Hatchability can be affected by poor nutrition, especially that involving a deficiency or imbalance of minerals and vitamins. Birds, like other animals need energy to carry out the actual process of mating and also deposits some nutrients in the eggs.
• In ostriches, egg size is an indicator of maternal nutritional status. Therefore egg size is also a good predictor of hatchability as well as chick survival at one month of age.
• Starving ostriches can breed poorly, while deficiencies of macro and micro nutrients can adversely affect hatchability and chick survival. Ostrich eggs have been found to contain high levels of selenium in shell and shell membranes, which is used by the developing embryo.
• Egg-laying hens require higher concentration of total calcium (3%) in feed for the formation of the shell. Ostrich hens laying a normal annual clutch of eggs and goes for natural incubation and brooding do not require increased the dietary calcium requirement. However, higher calcium is necessary when the eggs laid are continuously removed from the nest to encourage longer egg production. This can be provided through feed or by providing granulated calcium carbonate or oyster shells separately.
• Vitamin E and selenium as essential nutrients in breeder diets are necessary for egg production. The ration should also contain higher levels of minerals, vitamins, and trace elements.
• Good nutrition ensures better egg shell quality and porosity, higher egg yolk nutrient reserves, healthy embryos, improved hatchability, and better survivability. The influence of nutrients and deficiencies on egg hatchability is given in the following table.

Copper	Shell quality	Deaths at early blood stage; no malformations
Iodine	Hatchability	Prolongation of hatching time; incomplete abdominal closure
Iron	Hatchability	Low blood haemoglobin; poor embryonic circulation in candled eggs
Selenium	Egg production, hatchability	High incidence of embryo death early in incubation