subject: microRNA

MicroRNAs May Play a Key Role in Heat Stress Responses in Mammary Glands of Lactating Cows

MicroRNAs May Play a Key Role in Heat Stress Responses in Mammary Glands of Lactating Cows

A concern facing dairy farmers as the long, hot days of summer approach is the threat of heat stress in their cows. Experienced at temperatures above 80°F, heat stress affects growth and development as well as milk composition and volume. Heat stress is a major cause of low fertility in dairy cattle. It also increases susceptibility to metabolic disorders, mammary gland pathogens and mastitis. Compared with other livestock, cattle are unable to dissipate their heat load efficiently. Additional heat generated by the fermentation of food in the rumen compounds this problem. Cows’ sweating response is not highly effective, and the animals rely on respiration to cool themselves. Because of their inefficient response, cattle accumulate a heat load during the day that must be dissipated in cooler nighttime temperatures. In extreme weather conditions with overnight temperatures above 70°F, however, this doesn’t happen. Cattle experiencing increasing heat stress will stop feeding and become restless. They will then begin drooling and breathing more rapidly and with increased effort. They will also begin to group together, further exacerbating the problem. If not controlled, severe cases of heat stress will result in death. Economically, decreased milk yield and reproductive losses through hot summer months seriously affect the dairy industry. Increased occurrences of extreme weather conditions caused by ongoing global warming will only worsen these losses. Read More...

Ancient Aurochs Genome Contains the DNA Blueprint for Modern Cattle

Ancient Aurochs Genome Contains the DNA Blueprint for Modern Cattle

A preserved specimen of aurochs bone was discovered deep beneath the Derbyshire Dales in the UK in the 1990s. Aurochs are an ancient cattle breed domesticated around 10,000 years ago somewhere around modern day Iran. In Europe, the last of these animals were still found on a Polish royal reserve as recently as the 17th century. Park et al., have now extracted enough DNA from the ancient bone specimen to sequence the aurochs genome. When they compared the aurochs sequence to the DNA of cattle breeds we know and use in domestic agriculture today, they found a surprisingly high level in common with British and Irish cattle. Read More...

Designer cows may help improve human health

Designer cows may help improve human health

Designer jeans are fashioned to suit the individual needs of each human body shape. A good pair of well-cut jeans makes all the difference--they can be tailored to make a person comfortable at an informal BBQ, or a theatre premiere. The versatility of the primary design of jeans allows a good fit for one and all, and this is the key to their perpetual success. Like jeans, the same basic design for milk is used by each mammalian species; milk is formulated differently to suit the specific needs of the young of each species. Read More...

Milk vesicles uncovered

Milk vesicles uncovered

As dairy animals go, Holstein cows are record breakers. They produce more milk than any other breed or species, enough to fill a large tank truck over the course of their lifetimes. But the details of what's in their milk isn't entirely clear. Among the mystery ingredients are those that reside within exosomes, tiny membrane-bound packages that tote around proteins from their host cell. Read More...

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