Effects Of Betaine Instead Of Different Levels Of Methionine On Growth And Nutrients Utilization In Broilers

A total of 1800 broilers were chosen and assigned randomly to six treatments. Six groups were control group in which the content of methionine was added accordding to the feeding standard of broilers, 15%,25% total methionine replacement groups, 15%, 25% total methionine decreasement groups, and all supplemented methionine replacement group without adding methionine. The methionine was replaced by betaine at the ratio of 1:2. The experiment lasted 42 days.The results demonstrated that growth performance was similar in groups at 21 d of broilers (P>0.05), average daily gain and body weight were no significant different between first three groups and significantly higher than those of all supplemented methionine group (P<0.05). At 42 d of broilers, the average daily feed intake in 25% total methionine replacement group was significantly lower than that of 25% total methionine replacement group (P<0.05) and has no significant difference in other groups (P>0.05). Feed:gain ratio of 25% total methionine replacement group was significantly lower than that of 25% total methionine decreasement group and only added betaine group and has no significant difference compared with other groups (P>0.05). Moreover, Concentrations of GH and IGF-1 in the serum of broilers fed the diet 25% total methionine replacement group were higher (p < 0.05) than that of broilers of other treatments.Content of serum toal protein and globulin of 25% total methionine replacement group were higher (P< 0.05) compared to the boroilers of all supplemented methionine group, whereas this difference was not significant compared to control group and group 15% total methionine replacement group (P>0.05). Twenty-five pecentage of total methionine replacement group had the lower content of uric acid than other groups (P< 0.05). At 21 d of age, the concentration of serum LDL-C of 25% total methionine replacement group was significantly lower than that of other groups (P< 0.05), however, other fat metabolic indexes between all groups were not significantly different. At 42 d of age, all groups had no significant difirence in content of serum TG and activity of GOT, GPT (P>0.05). Content of serum TG of 25% total methionine replacement group was significantly lower than that of other groups (P< 0.05). Twenty-five pecentage of total methionine replacement group had higher content of HDL-C compared to control group and all supplemented methionine group (P< 0.05). Twenty-five pecentage of total methionine replacement group had highest activity of ALP and lowest activity of CK.Carcass yield, breast meat yield and abdominal fat yield had no significant difference between all groups (P>0.05), whereas semi-eviscerated yield of first three groups were significantly higher than that of last three groups (P< 0.05) at 21 d of age. At 42 d of age, breast meat yield and abdominal fat yield of 25% total methionine replacement group had no significant difference compared to 15% total methionine replacement group but were significantly different compared to other groups. Betaine instead of 15%, 25% total methionine had the trend to increase crude protein of breast meat and liver, and to decrease ether extract of liver.Nutrient utilization rate of DM in groups had no significant difference (P>0.05). Apparent utilization rate of energy, protein and ether extract in 25% total methionine replacement group had no significant difference with control group, 15% total methionine replacement group, and was improved 0.44%, 4.03%, 1.45% compared control group (P>0.05), moreover, true utilization rate of energy and protein in was improved 0.60% and 3.54% (P>0.05). However, apparent utilization rate of three nutrients in 25% total methionine replacement group was significantly higher than that of group of only supplemented betaine (P<0.05).These results indicated that: betaine instead of 25% total methionine of basal diet in broilers at 1:2 ratio could improve growth performance of broilers and carcass quality, promote protein and fat metabolism and had the tend to improve the utilization rate of nutrients.