Response of Growing Rabbits to Feed Restriction and Some Additives on Performance, Carcass and Hepatic Gene Expression under Egyptian Summer Conditions

This work aimed to study the response of growing female NZW rabbits to quantitative feed restriction (FR) at 60% of ad-libitum applied and the effect of adding either copper sulfate (CuSO4) and/or sodium bicarbonate (NaHCo3) to drinking water on performance and hepatic expression of apolipoprotein (apoA1), lipoprotein (cholesteryl ester transfer protein CETP, hepatic lipase HL) and insulin-like growth factor-I (IGF-1) during the summer period. Over the fattening period, rabbits fed AL during RES period (28-49 day of age) were significantly higher in most growth performance (GP) than RES-group, but all hepatic expression of genes tested decreased in feed restrictions group when compared to control on the other hand, adding either CuSO4 or NaHCo3 to drinking water slightly insignificant increase the expression of all the tested gens. When RES. rabbits fed freely after restriction (49-84 days of age). Logically, feed intake (FI) was significantly increased for AL group during FR period while, it was nearly similar, but FCE was more favorable for RES group throughout the whole period. Also, performance index (PI) was significantly higher for RES-groups. All values of carcass traits were significantly affected by FR. However, adding either CuSO4 or NaHCo3 to drinking water decreased GP during FR period. It can be concluded that FR had no significant effect on GP and slight decrease in gene expression for IGF-1 and lipoprotein gens, so it can applied FR to produce at slaughter age, rabbits with the same LBW of rabbits fed AL. Also, CuSO4 or NaHCo3 in drinking water is more practical to alleviate of heat load under the summer condition of Egypt.