β-Carotene and lutein in forage and bovine adipose tissue in two tropical regions of Mexico

Fresh pasture is rich in carotenoid pigments. Grazing cattle are likely to ingest substantial quantities of these pigments in their diet resulting in a yellow pigmentation of their adipose tissue. This is an undesirable characteristic in some countries such as Japan, Australia, New Zealand, and Mexico, and represents important economic losses for the producers. The objective of this study was to determine the carotenoid content of two forages (Digitaria decumbens and Cynodon dactylon) and its relation to the pigmentation of the adipose tissue of adult grass-fed cattle (crossbreds of Zebu, Brown Swiss, Charolais and Brahman) in two tropical regions of Mexico. In the dry tropics (DT), the forages contained on average 5.2mg/100g of β-carotene and 6.4mg/100g of lutein, whereas in the humid tropics (HT) they contained 14.9mg/100g of β-carotene and 18.5mg/100g of lutein. No significant differences in carotenoid content were found between the two forages in either region. The concentration of β-carotene in the adipose tissue of cattle grazed in HT (34.7μg/100g) was higher than that for cattle in DT (12.3μg/100g). The content of β-carotene in female animals (42μg/100g) was greater than that in males (26μg/100g). No regional or sex differences were found for lutein concentration. We conclude that climatic conditions can affect the amounts of carotenoids in forages. Furthermore, the carotenoids in pasture are deposited in cattle adipose tissue at different extents depending on the tropical region.