| This experiment was conducted to study the effect of growth restriction and realimentation on the growth associated indicators of pituitary, liver, duodenum and levels of plasma hormones in growing lambs. Eighty lambs (three month) with an average body weight of (14.72±1.10kg)were selected and divided into4groups: control group (CON), protein-restricted group (PR), energy-restricted group (ER), and protein-energy both restricted group (BR). The diet nutritional levels of the4groups were as follow:CP150.8,92.4,150.1and62.7g/kg, ME10.61,10.49,8.36and8.10MJ/kg during60days of nutrition restriction period. Four groups were fed the same diet (ME9.77MJ/kg, CP124.8g/kg) during90days of realimentation period. The experimental results were showed as follow:(1) Different dietary energy and nitrogen restriction resulted in reduced pituitary, liver, duodenum weight. All the three groups total cell number of pituitary, liver, duodenumand were lower than that of the control group. After90days of feed repletion, the cell number of three tissues in restricted groups were rised, and organ weight were compensated.(2) The change of growth axis hormones and receptor gene expression and the concentration in blood were influenced by nutrition restriction and compensation. With the decrease of the nutrition level,hormones and receptor gene expression in limit groups vary in certain degree. At the end of realimentation, the indicators measured in restricted groups can be restored to the level of the control group.(3)Under this experimental condition,the negative influence of limiting energy in ration were greater than limiting protein. Lamb fed low protein and energy diet (BR) showed the least compensatory growth. The ralationship between growth of Mongolian lamb and grain composition were significant, therefore, pastoral areas should pay attention to the nutrition composition of the diet in production practice. |
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