| The experiment was conducted to study the effect of dietary lysine supplementation on digestibility and growth performance.In experiment 1, Sixteen male Polled DorsetxSmall-tail Han lambs, with the average body weight of 6.13±0.65Kg, at the age of 30 days were divided into 4 groups, and fed with diets 1,2 and 3 during 30～75、76～120 and 121～240 days old respectively, to study the effect of dietary lysine supplementation on intake, body weight gain, digestibility and slaughter characteristics of lambs. In experiment 2, Eight female Polled DorsetxSmall-tail Han lambs, with the average body weight of 8.9±0.38Kg, were fitted with the abomasum canula at the age of 40 days, at the age of 60 days were divided into 2 groups, and fed with diets 1,2 and 3 during 60～80、81～120 and 121～240 days old respectively,and were supplemented with lysine at the dose of 1.2%、0.8% and 0.4% in diets 1, 2 and 3 respectively,the chyme of abomasum were collected,to study the effect of dietary lysine supplementation on the nutrients arriving at the abomasum. The results showed that, In experiment 1, during 30～75、76～120 and 121～240 days old,compared with that of the control group, the voluntary intake of dry matter in the group with best supplementation of lysine during 30～75、76～120 and 121～240 days old was increased by 14.10%(p< 0.01),37.70%(p<0.01) and 30.29%(p<0.01) respectively, the daily body weight gain was increased by 52.70%(p<0.01),11.35%(p<0.05) and 34.94%(p<0.01) respectively; the apparent digestibility of crude protein was increased by 18.23%(p<0.05)、11.06%(p<0.05) and 29.63%(p<0.01) respectively; the nitrogen retention rate was increased by 17.13% (p<0.01)、8.81%(p<0.05) and 22.37%(p<0.01) respectively; and the nitrogen retention amounts was increased by 28.37%(p<0.05)、40.37%(p<0.05) and 39.72%(p<0.05) respectively. The average daily body weight gain during 30～240 days old was increased by 23.25%(p<0.01). Also, the carcass weight, net meat weight, lean weight and fat weight at the age of 240 days were increased by 34-.72%(p<0.01)、37.41%(p<0.01)、42.98%(p<0.01) and 21.96%(p>0.05) respectively. It is concluded that the growth of lambs at the age below 240 days could be promoted by supplementation of untreated lysine; and the optimum content of lysine in diets for the lamb at 30～75、76～120 and 121～240 days old were 2.2%、1.5% and 0.7% respectively. In experiment 2, during 60～80、81～120 and 121～240 days old, compared with that of the control group,the voluntary intake of dry matter during 60～80、81～120 and 121-240 days old was increased by 12.57%(p>0.05)、19.38%(p<0.01) and 16.29%(p<0.01) respectively, the daily body weight gain was increased by 17.34%(p<0.05)^ 21.30% (p<0.01) and 17.76%(p<0.05) respectively; the digested amounts of DM in forestomach was increased by20.81%(p>0.05)、35.64%(p<0.05) and 19.97%(p<0.05) respectively, the digested amounts of OM in forestomach was increased byl7.18%(p>0.05)、31.05% (p<0.05) and 17.72%(p<0.05), the digested amounts of cellulose in forestomach was increased by26.98%(p<0.05)、50.06%(p<0.01) and 29.20%(p<0.05) respectively, the digested amounts of semi-cellulose in forestomach was increased by21.38%(p>0.05)、53.05%(p<0.01)and 19.53%(p<0.05)respectively; increased the amounts of the DM arriving at abomasum by7.01%(p>0.05)、11.59%(p<0.01) and 10.65%(p<0.01) respectively, increased the amounts of the OM arriving at abomasum by8.48%(p>0.05)、13.01% (p<0.01) and 12.14%(p<0.05), increased the amounts of the CP arriving at abomasum by11.13%(p>0.05)、21.73%(p<0.01) and 12.44%(p<0.01) respectively, increased the amounts of the microprotein arriving at abomasum by13.46%(p<0.05)、26.85%(p<0.01) and 15.08%(p<0.05) respectively, increased the amounts of the TAA arriving at abomasum by39.22%(p<0.01)、35.52%(p<0.01) and 28.27%(p<0.05) respectively, increased the amounts of lysine arriving at abomasum by 43.77%(p<0.01)、37.25%(p<0.01) and 34.38% (p<0.05) respectively, increased the amounts of TEAA arriving at abomasum by 9.21% (p<0.01)、34.40%(p<0.01) and 28.11%(p<0.05) respectively, increased the amounts of the free TAA arriving at abomasum by127.48%(p<0.01)、47.87%(p<0.05) and 11.68% (p>0.05) respectively, increased the amounts of free lysine arriving at abomasum by 81.50%(p<0.01)、46.99%(p<0.05)and 72.40%(p<0.01)respectively, increased the amounts of free TEAA arriving at abomasum by 139.87%(p<0.01)、57.76%(p<0.05) and 16.13% (p>0.05) respectively.From this research it is concluded that the growth of lambs at the age below 240 days could be promoted by supplementation of untreated lysine; and increased the intake, the digestibility of the diet in forestomach, and the absorbed nutrients, especially amino acids in abomasums. The optimum content of lysine in diets for the lamb at 30～80、81～120 and 121～240 days old were 2.2%、1.5% and 0.7% respectively. |
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