Abstract: Two groups of calves (n=5) weaning to 7-month old fed with corn stover(CT) and hay (H) respectively were selected and given mixed concentrate (2kg/d ).Effects of different quality on the digestibility and growth performance of calves during the age of weaning to 7-month were investigated. The results showed that daily feed intake of CT and H groups were 2.25 and 3.81 kg (P<0.01), respectively; dry matter intake (DMI), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP) and fat intakes in H group had higher than CFS, its digestibility were 63.6%, 51.2%, 43.5%, 64.3%, 55.6% and 57.5%, 43.3%, 40.4%, 44.4%, 59.4%; besides digestibility of CP in two groups were significantly different (P<0.01). Daily gain in H and CFS groups were significant (0.788 and 0.522 kg/d, P<0.01), body slanting length (18.3 and 9.5 cm) and chest girth were significant (P>0.05), change of heights was no difference. It was concluded that comparing with corn-straw，supplementing grass hay would increase the dry matter intake and nutrient digestibility of calves fed during the age of weaning to 7-month and improve the growth performance, especially development of body slanting length and chest girth.

Key words: weanling calves; forage; digestibility of nutrient; development