Abstract: 8 of Small Tail Han sheep × Poll Dorset lambs, 30-day-old, with the body weight of (6.9±1.0) kg were divided into 2 groups randomly (n=4 each group), to study on the effect of oral administration of formalin(OAF) on the intake, digestion, metabolism, dressing performance and formaldehyde residual of lamb. The results showed that at three stages of 55 to 80, 95 to 120 and 125 to 150 days’ old, the dry matter intake were (567.3±27.5), (752.4±9.01) and (1044.1±30.8) g/(lamb·day) respectively in control group, and increased by 22.02% (P<0.01),28.75% (P<0.01) and 41.79% (P<0.01) respectively in the group of OAF; the nitrogen retention were (12.3±0.8),(13.6±0.2) and (18.0±0.6) g/(lamb·day) respectively in control group, and increased by 25.20% (P<0.01)，41.91%(P<0.01) and 46.11%(P<0.01)respectively in OAF group；the daily body weight gain were (157.1±11.7),(246.4±24.4) and (250.0±8.3) g/(lamb·day) respectively in control group，and increased by 18.20% (P<0.05）,23.21% (P<0.05) and 27.16% (P<0.01) respectively in OAF group. However, the digestibility of diet had no significant difference between two groups. At 240 days’old, in control group and OAF group the carcass weight were （20.3±1.78） kg and (24.55±1.14) kg (P<0.01) respectively, the dressing percentage were 48.59%±1.08% and 50.46%±1.02% (P<0.05) respectively, the lean meat percentage were 65.22%±1.57% and 64.8%±1.11% (P>0.05) respectively. The formaldehyde contents in blood, muscle, kidney, liver, rumen tissue and small intestine tissue were (1.84±0.44) mg/L,(0.35±0.26) mg/kg,(1.10±0.67) mg/kg,(0.74±0.34) mg/kg,(0.91±0.72) mg/L and (0.79±0.41) mg/L respectively in control group and were (1.47±0.61) mg/L,(0.54±0.34) mg/kg,(1.65±0.71) mg/kg,(0.91±0.38) mg/kg,(2.03±0.71) mg/L and (0.85±0.42) mg/L respectively in OAF group. It is concluded that OAF of lamb could increase the intake without affecting the digestibility of diet, the digested amount of diet and the body weight gain; and the effect of OAF was age-dependent; the carcass weight and dressing percentage lamb were increased by OAF without the decreasing of lean meat percentage of carcass; the content of formaldehyde in the tissue of lamb orally administrated with formalin for 210 days were bellow 2.0 mg/kg.

Key words: lamb; formalin; intake; digestion; growth