Ostriches, the largest and heaviest living birds, are known for their impressive size and speed. Reaching up to 9 feet tall and weighing upwards of 300 pounds, these flightless birds can sprint at speeds of up to 43 mph. To sustain these remarkable physical attributes, ostriches require a carefully balanced diet. This article delves into the intricate details of the ostrich diet, covering their natural feeding habits, nutritional requirements, and the impact of diet on their health and productivity.
Ostrich Overview
Common ostriches (Struthio camelus) are native to the savannas and shrublands of southern and eastern Africa. These distinctive birds are characterized by their long necks, muscular legs, and claw-like feet, making them well-adapted for life in open environments. Adult males are easily recognizable by their black feathers and white tails, while females are mostly covered in brown feathers.
Wild ostriches can live up to 30-40 years and communicate using various vocalizations, including chirps, hisses, growls, and honks. Male ostriches can also produce a booming sound by inflating a special sac in their throat, a sound that can travel across great distances.
Natural Diet of Wild Ostriches
Ostriches are omnivores, with a diet that mainly consists of plant-based foods. In the wild, they primarily consume leafy greens, flowering plants, roots, grasses, and succulents. They also supplement their diet with fallen fruit and occasionally feed on small animals such as mice, lizards, frogs, grasshoppers, and locusts.
According to research, wild ostrich diets typically comprise:
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- 60% leafy plant material
- 15% fruits or legumes
- 5% insects or small-sized animals
- 20% grains, salts, and stones
Ostriches do not have teeth, so they swallow sand and pebbles to help grind down food in their stomachs. These stones act as gastroliths, aiding in the mechanical breakdown of tough plant fibers.
Feeding Habits and Behaviors
Ostriches are sociable birds that often live in nomadic groups of 5 to 50. They are diurnal, meaning they are most active during the day, but may also be active on moonlit nights. Their acute eyesight and hearing help them to detect predators from far away.
Ostriches spend up to 8 hours each day foraging for food, consuming between 1 kg and 1.8 kg daily. They adapt their foraging to include whatever is seasonally available, and unlike mammals, ostriches will eat entire plants, including roots and bulbs, rather than just eating leaves or stems.
Digestion in ostriches takes around 36 hours. The grit and stones in their gizzard serve as a grinding mechanism to break larger indigestible foods into smaller pieces.
Seasonal Variations in Diet
The ostrich diet varies with the seasons, reflecting the availability of different food sources.
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Spring and Summer
Spring and summer bring a wider variety of vegetation due to increased rainfall. During these seasons, ostriches consume more green grasses, shoots, seeds, and fruits.
Fall and Winter
As temperatures cool in the fall, plants begin to die back, leading to a shift in the ostrich diet. Seeds and roots become the predominant food sources, and ostriches increase their intake of grit to cope with the tougher foods. In winter, insects become a more important part of their diet, as less fresh plant matter is available.
The Digestive System of Ostriches
Ostriches have a unique digestive system that allows them to process tough plant matter efficiently. Key features of their digestive system include:
- Proventriculus: A large glandular stomach located between the esophagus and the gizzard, functioning as a storage area similar to a crop.
- Gizzard: A muscular stomach that uses ingested sand and small rocks to grind down food.
- Long Intestines: Ostriches have long intestines, reaching about 46 feet in length, allowing for extended digestion and microbial fermentation of fibrous plants.
- Volatile Fatty Acids (VFA): The fermentation process in the intestines results in the production of VFAs, which can be absorbed and used as energy.
Water Intake and Hydration
Ostriches obtain water from the vegetation they eat, allowing them to go several days without drinking open water. However, they cannot survive long-term without access to open water sources. Fruits are a key source of moisture for ostriches, with favorites including abal, acacia, baobab, beech, wild melon, monkey orange, and guarri.
Diet in Captivity
Farm-raised ostriches typically receive a special pellet diet supplemented with fresh fruits and vegetables. These pellets are formulated to provide a balanced mix of nutrients. Ratite pellets contain a balanced mix of alfalfa (which is high in moisture, fiber and protein), iron oxide, vitamins and calcium. Maize is a common ingredient, offering concentrated carbohydrates as a good energy source, and peanuts may be added as a source of fats and protein. Grit, pebbles, stones and sand are vital to an ostrich’s digestive processes, both in captivity and in the wild. The rough edges of the stones swallowed and held in the ostrich’s gizzard helps to grind food into smaller pieces to facilitate the digestion process. Supplementary food given to farm-raised ostriches includes plenty of green fodder crops, such as cabbages and kale, as well as oranges, watermelons and carrots which offer an important source of hydration, calcium and protein.
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Nutritional Requirements
The nutritional needs of ostriches vary across different life stages, impacting growth and reproductive performance. Essential nutrients include 20-24% crude protein (CP) and 12-19% crude fiber for optimal development, especially in early growth. As ostriches reach sexual maturity, a diet rich in amino acids, vitamins, and carbohydrates becomes vital for optimizing fertility and reproductive performance.
Ostrich Chicks
Younger ostriches require a diet that is rich in protein in their early weeks and months of life. This is a vital time in their development, with rapid growth to gain their full adult height by the time they reach 18 months. An intensely nutritious diet is needed to support this accelerated and constant growth: baby ostriches weigh about 1 kg (2.2 lb) when they hatch and within 18 months reach about 140 kg (in excess of 300 lb). Adult ostriches need foods that are rich in fiber maintaining body functions and preventing obesity.
Ingredients in Ostrich Feed
Common ingredients in ostrich feed include:
- Alfalfa: Makes up over 40% of the total feed, providing moisture, fiber, and protein.
- Corn: Provides essential nutrients such as iron, zinc, potassium, and is high in energy.
- Soybean meal, peanut meal and fishmeal: Major protein sources in ostrich feeding.
Non-GMO Feed
While sourcing exclusively non-GMO feed components is expensive, the modified DNA in GMO feed does not transfer to the meat of the animals that consume it.
Health Benefits of Ostrich Meat
Ostrich meat has gained attention as a healthy alternative to traditional red meats due to its low fat content (0.34% or up to 3g/100 g) and high protein level (16.5% - 22.26% or 22-24g/100 g), outperforming beef in both categories. Ostrich muscles also contain high concentrations of myoglobin (1.14%) as compared to goat (1.07%), contributing to iron storage, with levels ranging from 20-30 micrograms of Fe/g on wet weight basis. The meat is rich in favorable omega-3 fatty acids with lower n6:n3 (3.02) as compared to poultry (7.67) and beef (8.86) which align with dietary recommendations by WHO for prevention of chronic diseases to reduce saturated fat intake in favor of polyunsaturated fatty acids (PUFAs) to lower the risk of coronary heart disease. Ostrich meat is considered an ideal choice for health-conscious individuals who prefer red meat.
Ostrich meat meets this criterion, with a P/S ratio of 0.53. Ostrich meat is characterized by a higher polyunsaturated fatty acid (PUFA) content compared to beef, chicken, and turkey, as well as a lower sodium content in ostrich meat (43.5-57.85mg/100 g) as compared to turkey (123mg/100 g), poultry (64-83mg/100 g), and beef (65-89mg/100 g), making it a healthier option for individuals with hypertension. The PUFA ratio in ostrich meat fat has been reported as 27.54 ± 1.01, alongside a notable mineral content, further enhancing its nutritional value. Its high natural water-binding capacity and relatively high mean pH of 7.2, which increases post-24 hours of slaughtering, further enhance its suitability for processing, reducing the need for artificial moisture retainers like phosphates.
Husbandry Challenges and Health Issues
Husbandry challenges, such as the failure of chicks to absorb the yolk sac in their early days may hinder growth and development. Suboptimal nutrition, combined with overcrowding, pecking behaviour, inadequate ventilation, excessive heat, and poor husbandry practices, can result in high chick mortality, nutritional stress, and increased susceptibility to diseases. Gastric impaction, often linked to poor management, is a significant contributing factor. Bacterial pathogens such as Escherichia coli, Campylobacter jejuni, Pseudomonas aeruginosa, Salmonella spp., and Clostridium spp. are commonly implicated in ostrich enteritis. The ostrich population is prone to multidrug-resistant pathogens, especially E. coli and Salmonella species.
Viral diseases such as Newcastle Disease are particularly critical, with mortality rates reaching 80-85% in ostriches aged 3-6 months in various regions. Leg deformities, often resulting from poor nutrition, are another common issue leading to early chick mortality.
Foods to Avoid
Certain foods can be toxic to ostriches and should be avoided:
- Onion and avocado: These are toxic to ostriches and should never be offered.
- Acorns: Contain large amounts of tannic acid, which can lead to sickness.
- Foods containing chocolate, caffeine, or alcohol: These are harmful to all birds, including ostriches.
The Role of Ostriches in Ecosystems
Free-roaming ostriches play a vital but unintentional role in seed dispersal throughout their habitats. They graze on wild grasses and other vegetation and as they wander, they will naturally poop.
Human-Ostrich Interactions
In tourist hotspots, ostriches may cross paths with humans and show curiosity towards them. It is wise to keep a distance to avoid being bitten or kicked. Some farms offer guided feeding experiences where visitors can safely feed ostriches approved fruits and vegetables like chopped apples, pears, grapes, squash, carrots, and bok choy.