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|標題:||Administration of triiodothyronine and dopamine to broiler chicks increases growth, feed conversion and visceral organ mass|
|期刊/報告no：:||Poultry Science, Volume 82, Issue 2, Page(s) 285-293.|
|摘要:||The influences of triiodothyronine (T-3) or dopamine (DA) administration on growth, feed conversion, and visceral weights in broiler chicks between the ages of 6 and 12 d posthatch were investigated. In Trial 1, six chicks at age 6 d were randomly administered one of the following treatments: 0.37, 0.74, 1.48, and 2.96 mumol T-3/kg BW or 0.07, 0.14, 0.28, and 0.56 mumol DA/kg BW. Both T-3 and DA were administered via intraperitoneal injections between the end of sternum and the ends of os pubis, with 0.9% saline as the excepient. In addition, two groups of six birds each were either not injected or injected with excepient only, as controls. Four replications were carried out with a total of 264 chicks. Heart weight as a percentage of feed-deprived body weight (FDBW) of the chicks injected, with 2.96 mumol T-3/kg BW was heavier than that of controls. Other variables measured were not significantly different between treatments. In trial 2, six chicks at age 6 d were randomly administered, one of the following treatments: 0.56, 1.12, 2.24, and 4.48 mumol T-3/kg diet or 0.40, 0.80, 1.60, and 3.20 mumol DA/kg diet as well as a nonsupplemented control. Four replications were carried out with 216 chicks. The results in Trial 2 showed that the effects of T-3 (X, mumol/kg diet) on body weight gain (Y-1, g) and feed consumption (Y-2, g) were linear (Y-1 = 310 - 21.5X, R-2 = 0.868, P < 0.001 and Y-2 = 398 - 22.3X, R-2 = 0.765, P < 0.001, respectively). The feed conversion ratio, the weight of liver, the weights of various intestinal segments, the lengths of the duodenum, jejunum and the ileum, as well as weight per centimeter jejunal length, gizzard weight as percentage of FDBW, and the duodenal length per kilogram FDBW all had linear responses (P < 0.05) to the level of dietary supplementation of T-3. The effect of dietary supplementation of T-3 on the heart weight was quadratic (Y-16 = 2.58 + 0.89X - 0.17 X-2, R-2 = 0.526, P < 0.01). Similarly, the weights of pancreas and gizzard, the heart weight as a percentage of FDBW and the pancreas: weight as a percentage of FDBW all had second-order curve responses. Dietary DA supplementation exerted no. effect on the variables measured except that the regression of the heart weight as a percentage of FDBW on dietary DA supplementation (X-1, mumol/kg diet) existed, namely, Z(1) = 0.64 + 0.24 X-1 - 0.23 X-1(2) + 0.05 X-1(3) (R-2 = 0.868, P < 0.05).|
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