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The biologist Thierry Lodé proposed (2001, 2012) five modes of reproduction based on the relationship between the zygote (fertilised egg) and the parents: [1] [2]. Ovuliparity: fertilisation is external, the oocytes being released into the environment and fertilised outside the body by the male. [1]
Female cattle, also referred to as "heifers" in agriculture, will gradually enter standing estrus, or "standing heat," starting at puberty between 9 and 15 months of age. The cow estrous cycle typically lasts 21 days. [5] Standing estrus is a visual cue which signifies sexual receptivity for mounting by male cattle.
[8] [9] Cattle breeds vary widely in size; the tallest and heaviest is the Chianina, where a mature bull may be up to 1.8 m (5 ft 11 in) at the shoulder, and may reach 1,280 kg (2,820 lb) in weight. [10] The natural life of domestic cattle is some 25–30 years. Beef cattle go to slaughter at around 18 months, and dairy cows at about five years.
According to one preliminary study, the bulbourethral gland fluid might not contain any sperm, [10] whereas another study showed some men did leak sperm in potentially significant quantities (in a range from low counts up to 50 million sperm per ml) into the pre-ejaculatory fluid, [9] potentially leading to conception from the introduction of ...
The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones , and pheromones are also important accessories to the reproductive system. [ 1 ]
Udder of a cow. An udder is an organ formed of two or four mammary glands on the females of dairy animals and ruminants such as cattle, goats, and sheep. [1] An udder is equivalent to the breast in primates, elephantine pachyderms and other mammals.
The etymology of the term "freemartin" is uncertain: speculations include that "free" may indicate "willing" (referring to the freemartin's willingness to work) or "exempt from reproduction" (referring to its sterility, or to a farmer's decision to not bother trying to breed a freemartin, or both), or that it may be derived from a Flemish word for a cow which gives no milk and/or has ceased to ...
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