1Department of Animal Science, Faculty of Agriculture and Natural Resources, Arak University, Arak, Iran
2Department of Veterinary and Food Hygiene, University of Scientific-Applied, Arak, Iran
3Department of Animal Science, Faculty of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
Receive Date: 28 August 2014,
Revise Date: 06 December 2014,
Accept Date: 15 January 2015
Forty growing ram lambs (Lori-Bakhtiari breed) averaging 28 kg (±1.5) were allocated in this study to evaluate the optimal dietary energy density in a lamb fattening enterprise in Iran. The feed intake (FI), body weight (BW), gain to feed ratio (G:F) and carcass characteristics were studied. Four treatments differed in metabolizable energy content (ME) as follow; 2, 2.3, 2.6 and 2.9 Mcal/kg for treatments 1 to 4, respectively. The study lasted 120 days and all the experimental lambs were slaughtered and carcass composition was compared among treatments. Average daily gains were 230, 252, 267 and 259 g/d for treatments 1 to 4, respectively (P<0.01). Moreover, lower energy density resulted in up to 19% greater FI (P<0.01) and higher F:G ratio (P<0.01) and therefore lower carcass growth efficiency (P<0.05). Higher energy density improved G:F ratio; but caused fatter carcasses compared to lower dietary energy levels. In addition to fatter carcasses for higher energy diets, the greatest tail-fat weight was observed for treatment 4 (2.9 Mcal/kg) and may explain the lower feed efficiency in this treatment. The values for lean mass weights were 12.7, 14.1, 14.7 and 12.7 kg for treatments 1 to 4, respectively. Overall, the best carcass efficiency was found with treatment 3. Based on these results, energy density of 2.6 Mcal/kg may be recommended for growing Lori-Bakhtiari male lambs in a fattening enterprise under the conditions of this trial.
AOAC. (2000). Official Methods of Analysis. 15th Ed. Association of Official Analytical Chemists, Arlington, VA, USA.
Beauchemin K.A., McCelland L.A., Jones S.D.M. and Kozub G.C. (1995). Effects of crude protein content, degradability and energy concentration of the diet on growth and carcass characteristics of market lambs fed high concentrate diets. Canadian J. Anim. Sci. 75, 387-395.
Boggs D.L., Bergen W.G. and Hawkins D.R. (1987). Effects of tallow supplementation and protein withdrawal on ruminal fermentation, microbial synthesis and site of digestion. J. Anim. Sci. 64, 907-914.
Dinius D.A. and Baumgardt B.R. (1970). Regulation of food intake in ruminants. 6. Influence of caloric density of pelleted rations. J. Dairy Sci. 53, 311-316.
El-karim A.I.A. and Owen J.B. (1987). Post-weaning growth performance, carcass characteristics and preliminary heritability estimates for some carcass triads of two types of Sudan desert sheep on intensive feeding. J. Agric. Sci. 109, 531-538.
Farid A. (1991). Carcass physical and chemical composition of three fat tailed breeds of sheep. Meat Sci. 29, 109-120.
Farid A., Makarechian M. and Sefidbakht N. (1977). Cross breeding of Iranian fat tailed sheep: lamb performance of Karakul, Mehraban and Naeini breeds. J. Anim. Sci. 44, 542-548.
Gatenby R.M. (1986). Sheep Production in the Tropics and the Sub-Tropics. Longman, New York, USA.
Givens D.I. and Moss A.R. (1994). Effect of breed, age and bodyweight of sheep on the measurement of apparent digestibility of dried grass. Anim. Feed Sci. Technol. 46, 155-162.
Haddad S.G. and Husein M.Q. (2004). Effect of dietary energy density on growing performance and slaughtering characteristics of fattening Awassi lambs. Livest. Prod. Sci. 87, 171-177.
Koc H. (1996). The effect of sex and initial body weight of the fattening and carcass characteristics of Karaman lambs and economic analysis of fattening. MS Thesis. Graduate School of Natural and Applied Science, Gaziosmanpasa Univ., Turkey.
Landim A.V., Castanheira M., Fioravanti M.C.S., Pacheco A., Cardoso M.T.M., Louvandini H. and Mc Manus C. (2011). Physical, chemical and sensorial parameters for lambs of different groups, slaughtered at different weights. Trop. Anim. Health Prod. 43, 1089-1096.
Lourenco A.L.G., Dias-da-Silva A.A., Fonseca A.J.M. and Azevedo J.T. (2000). Effects of live weight, maturity and genotype of sheep fed a hay-based diet, on intake, digestion and live weight gain. Livest. Prod. Sci. 63, 291-296.
Mahgoub O., Lu C.D. and Early R.J. (2000). Effects of 1 dietary energy density on feed intake, body weight gain and carcass chemical composition of Omani growing lambs. Small Rumin. Res. 37, 35-42.
NRC. (1985). Nutrient Requirements of Sheep. 7th Ed. National Academy Press, Washington, DC, USA.
Perez P., Maino M., Mardones G. and Pokniak J. (2002). Carcass charachtersrics and meat quality of Suffolk Down suckling lambs. Small Rumin. Res. 44, 233-240.
Ranilla M.J., Carro M., Valdes C., Giraldez F. and Lopez S. (1997). A comparative study of ruminal activity in Churra and Merino sheep offered alfalfa hay. Anim. Sci. 65, 121-128.
SAS Institute. (1996). SAS®/STAT Software, Release 6.11. SAS Institute, Inc., Cary, NC. USA.
Sayili M., Cimen M. and Karaalp M. (2009). The effects of different initial weight and sex on the fattening performance and economic analysis of fat-tailed lambs in pasture feeding in Turkey. Bulgharian J. Agri. Sci. 15, 435-440.
Shadnoush G.H., Ghorbani G.R. and Edris M.A. (2004). Effect of different energy levels in feed and slughter weights on carcass and chemical composition of Lori- Lori-Bakhtiari ram lambs. Small Rumin. Res. 51(3), 243-249.
Snowder D.G., Glimp H.A. and Field R.A. (1994). Carcass characteristics and optimal laughter weight in four breeds of sheep. J. Anim. Sci. 72, 932-937.
Yakan A. and Unal N. (2010). Meat production traits of a new sheep breed called Bafra in Turky 1. Fattening, slughter and carcass characteristics of lambs. Trop. Anim. Health Prod. 42, 751-759.