Abstract
This experiment was designed to investigate the effect of different level of energy on growth, carcass traits, body composition, digestibility and some blood parameters. Twenty one Awassi lambs (4 month old and 23 kg body weight) were used and after 10 days of adaptation, the lambs were divided equally and randomly and penned individually into three treatment groups, and fed ad lib on low (10.8 T1) medium (11.6 T2) and high (12.3 T3 MJ/kg DM). After 72 days of fattening, 5 lambs from each treatment were chosen and slaughtered. Results revealed that lambs of T3 had numerically higher daily gain (189.72 g), lower dry matter intake (849.46 g), higher feed efficiency (4.7), higher dressing percentage (48.43) and a significant increase (P≤0.05) was noticed in dry matter, organic matter, crude protein, nitrogen free extract and total digestible nutrient as compared with lambs received low or medium level of energy. It could be concluded that the high dietary energy produce the best performance, nutrient digestion and carcass trait of lambs.
Highlights
In Iraq, sheep are considered the most important farm animals, and an enormous share of income come from the sale of lambs
It have been indicated that increasing dietary energy level generally can improve the daily gain and feed efficiency of sheep [15,19], and most are in accordance that feed intake increased with increasing protein level and decreased with increasing energy level [3]
Such result may be related to feed intake which is regulated by dietary energy density in ruminants
Summary
In Iraq, sheep are considered the most important farm animals, and an enormous share of income come from the sale of lambs. Their importance is further enhanced because they are the most suitable farm animals to the extensive area of arid and semi- arid of the country, as well as, the major sources of livelihood for the rural inhabitants of the area [5]. It is well documented that proper growth and development of growing lambs depends heavily on the animals level of nutrition [30] in which energy is considered the major dietary element that is responsible for the efficient utilization of nutrient and thereby the productivity and gain of an animal [19]. Following an adaptation period for 10 days, the lambs were randomly and allocated and individually penned (1 ×2 m) into three treatment groups and fed concentrate ad-lib containing 10.9 (T1), 11.7
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