Expression of candidate genes for residual feed intake in tropically adapted Bos taurus and Bos indicus bulls under thermoneutral and heat stress environmental conditions

The objectives of this study were to measure the relative expression of the ATP1A1, NR3C1, POMC, NPY, and LEP genes in Caracu (Bos taurus) and Nelore (Bos indicus) bulls submitted to feed efficiency tests at high environmental temperatures, and to evaluate differences in adaptability to tropical conditions between breeds. Thirtyfive Caracu and 30 Nelore bulls were submitted to a feed efficiency test using automated feeding stations. At the end of the test, the animals were subjected to thermoneutral (TN) and heat stress (HS) conditions. Blood samples were collected after the exposure to the TN and HS conditions and the relative expression of genes was measured by qPCR. The bulls exhibited lower expression of ATP1A1 in the HS condition than in the TN condition (1.98 +/- 0.27 and 2.86 +/- 0.26, P = 0.02), while the relative expression of NR3C1, POMC, and LEP did not differ (P 0.05) between climatic conditions. The breed and feed intake influenced NPY and LEP expression levels (P < 0.05). Different climate conditions associated with residual feed intake can modify the gene expression patterns of ATP1A1 and NPY. The association observed among all genes studied shows that they are involved in appetite control. Bos taurus and Bos indicus bulls exhibited similar adaptability to tropical climate conditions.

Automated summary

This study investigated the gene expression in Caracu and Nelore bulls under high environmental temperatures, finding lower expression of ATP1A1 in heat stress conditions. Breed and feed intake influenced the expression levels of NPY and LEP, while different climate conditions and residual feed intake could modify gene expression patterns. The association observed among all genes studied suggests their involvement in appetite control, and both Bos taurus and Bos indicus bulls showed similar adaptability to tropical climate conditions.