Effect Of Feed Restriction On Compensatory Growth On Sheep Production Strategy For Grazing System Of Sheep In The Agro-pastoral Ecotone

Livestock production in northeast mixed cropping and animal husbandry of China depends on natural pasture and crop residues and is largely influenced by availability that fluctuates throughout the year. However, the natural grassland shows great sensibility to grazing at certain phenological stage of pasture, such as early spring. The objective of this experiment was to determine the effect of different levels of feed restriction on growth rate and body dimensions of re-alimented lambs in spring.Hay-feeding strategy in early spring could help overcome this sensitive season. Lambs could saved a lot of herbage during the whole restriction period. After restriction, the refeed lambs showed higher ADG than CK due to the high quality pasture and high feed conversion efficiency. Even in October, when pasture quality declined much, restricted lambs remained comparative high ADG. Ujumuqin lambs, after 57 days of feed restriction below their daily maintenance nutrition requirement, may not achieve similar compensatory growth similar to their non-retarded counterparts with 113 days of compensatory feeding. Perhaps, it needs more time for entirety compensatory.The development of various components of an animal is affected by plane of nutrition. Various body dimensions of immature sheep react differentially under restricted nutritive quality and during realimentation when animals receive sufficient nutrients again. In general, bone dimensions such height and body length are less affected than width and body circumference. After realimentation, those parts which are most affected during restriction show higher gain. Bone measurements such as trunk length and height at withers have a more stable character than LW and other body dimensions.We found that the restricted groups had a significant longer intake time than the control group, meanwhile, the rate of intake of the former group was slightly larger than that of the latter one. However, in the aspect of intake per bite, both had no significant difference. To conclude, the difference of the total intake was mainly resulted from the difference in the intake time and the rate of ingestion.