Genetic improvement of adaptation and reproduction to enhance sustainability of cow-calf production in the Southern United States
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abstract
Because of the white(unpigmented) skin on the face of Hereford and Hereford crossbred cattle, they are more prone to cancer of the eyelid and/or eyeball ("cancer eye") than cattle of other breeds. Production losses due to cancer eye are a major concern in the beef cattle industry. However, there is considerable variation of the amount of pigmentation of the eyelids in Herefords, ranging from totally unpigmented eyelidsto various degrees of pigmentation, to total pigmentation of the eyelids, in some cases with pigmented hair accompanying the pigmented skin of the eyelid.This effect of eye pigmentation on susceptibility to cancer eye has been studied in the past, but, with current technology, updated characterization of eye pigmentation in Hereford straightbreds and crossbreds, would facilitate the possible identification of genes (or genomic regions) associated with eye pigmentation and/or cancer eye.Brahman cattle are well adapted to tropical and subtropical conditions and are widely used for crossbreeding in the southern United States. In addition to improvedheat and parasite tolerance, Brahman crossbred exhibit high levels of hybrid vigor when crossed with the British and Continental European breeds. However, associated with their heat tolerance, they lack the cold tolerance of theBritish and Continental European breeds. The lack of cold tolerance is mostly a problem in new-born calves. When the temperature is below about 40 degrees Fahrenheit, there is a serious problem with purebred Brahman calves failing to nurse their dams without assistance, especially if there is any precipitation associated with the cool (or cold) weather.There is also considerable variation in the conformation of the udder and teats in Brahman cattle. Poor udder quality, defined by large teats and/orpendulous udder suspension can cause difficulties with calves ability to nurse, even in warm weather.Poor udder quality isa major problem under cold conditions.Udder quality declines with age and, therefore, as cows get older, progressively more of their cales have difficulty nursing without assistance.As with eye pigmentation, updated characterization of udder characteristics would facilitate the possible identification of genes (or genomic regions) associated with udder problems.
