References

Avenda�o, R.L., V.F.D. Alvarez, R.L. Molina, Q.J.S. Saucedo and C.A. Correa, 2004. Fattening pelibuey sheep and his crosses with dorper and katahdin under conditions of heat stress: Preliminary results. Memories of the XXVIII Buitria Congress. M�xico.

Bonilla, T.G., E.S. Aguilar, J.E. Ortega, H.G. Torres, R.P. Diaz and S.D. Romero, 2003. A note on pre weaning growth of pelibuey and F1 katahdin pelibuey lambs in tropical conditions. XII Natonal Congress of Sheep Production. AMTEO. M�xico.

Bores, Q.R., A.M. Vel�zquez and A.M. Heredia, 2001. Evaluation of energy levels and weight slaughter of terminals suffolk lambs with pelibuey. II Latin American Congress of Specialists in Small Ruminants and South American Camelids. Mexico.

Bores, Q.R., M.A. Velazquez and A.M. Heredia, 2002. Evaluacion de razas terminales en esquemas de cruza comercial con ovejas de pelo F1. Tec. Pec. Mex., 40: 71-79.

Bradley, J.S., 2005. Performance evaluation, carcass characterization and palatibilty assessment of hair sheep. M.Sc. Thesis, Technology University, Texas, USA.

Burke, J.M. and J.K. Apple, 2005. Growth performance and carcass traits of forage-fed hair sheep wethers. Small Rumin. Res., 67: 264-270.
CrossRef  |  

Caton, J.S. and D.V. Dhuyvetter, 1997. Influence of energy supplementation on grazing ruminants: Requirements and responses. J. Anim. Sci., 75: 533-542.

Faverdin, P., 1999. The effect of nutrients on feed intake in ruminants. Proc. Nutr. Soc., 58: 523-531.
PubMed  |  

Ferrell, C.L., 1993. Metabolism of Energy. In: The Rumiante, Digestive Physiology and Nutrition, Church, C.D. (Ed.). Acribia, Spain, pp: 283-303.

Ferrell, C.L., K.K. Kreikemeier and H.C. Freetly, 1999. The effect of supplemental energy, nitrogen and protein on feed intake, digestibility and nitrogen flux across the gut and liver in sheep fed low-quality forage. J. Anim. Sci., 77: 3353-3364.
PubMed  |  

Fisher, D.S., 2002. A review of a few key factors regulating voluntary feed intake in ruminants. Crop Sci., 42: 1651-1655.
CrossRef  |  Direct Link  |  

Forbes, J.M., 1986. The Voluntary Food Intake of Farm Animals. Butterworth-Heinemann, United Kingdom, ISBN: 978-0-408-11154-6, Pages: 206.

Freking, B.A. and K.A. Leymaster, 2004. Evaluation of dorset, finnsheep, romanov, texel and montadale breeds of sheep: IV. Survival, growth and carcass traits of F1 lambs. J. Anim. Sci., 82: 3144-3153.
PubMed  |  

Garcia, M.C., 2003. Prospects for livestock tropical of mexico before globalization. XXVII National Congress Buiatria. M�xico, pp: 172-182.

Jung, H.G. and M.S. Allen, 1995. Characteristics of plant cell walls affecting intake and digestibility of forages by ruminants. J. Anim. Sci., 73: 2774-2790.
CrossRef  |  PubMed  |  Direct Link  |  

MacLeod, K.R. and R.L. Baldwin, 2000. Effect of diet forage: Concentrate ratio and metabolizable energy intake on visceral organ grown and in vitro oxidative of gut tissues in sheep. J. Anim. Sci., 78: 760-770.
PubMed  |  

Macedo, R. and L.A. Aguilar, 2005. Productive performance of confined pelibuey lambs fed mixed diet based on agro-industrial by-products and crop residues. Livest. Res. Rural Dev., 17: 1-5.

Mader, T.L., S.M. Holt, G.L. Hahn, M.S. Davis and D.E. Spiers, 2002. Feeding strategies for managing heat load in cattle. J. Anim. Sci., 80: 2373-2382.
PubMed  |  

Maxwell, S.E. and H.D. Delaney, 2004. Designing Experiments and Analyzing Data: A Model Comparison Perspective. 2nd Edn., Lwarence Erlbaum Associates, London, pp: 868.

Milne, C., 2000. The history of dorper sheep. Small Rumin. Res., 36: 99-102.
PubMed  |  

NRC, 1985. Nutrient Requirements of Sheep. 6th Edn., National Academy of Sci., Washington, USA., pp: 122.

Nogueira, B.N., V.R. Vasconcelos, W.E. Alcido and M.R.A. Ara�jo, 2005. Bioeconomic efficiency of F1 dorper lambs-santa Ines for meat production. Pesq. Agropec. Bras., 4: 825-831.

Partida, P.J. and R.L. Martinez, 1992. Behavior of pelibuey sheep fed with 2 levels of energy in 4 periods of growth. Technol. Pec. Mex., 30: 1-11.

Ross, T.T., L. Goode and A.C. Linnerud, 1985. Effects of high ambient temperature on respiration rate, rectal temperature, fetal development and thyroid gland activity in tropical and temperate breeds of sheep. Theriogenology, 24: 259-269.
PubMed  |  

Snowder, G.D. and S.K. Duckett, 2003. Evaluations of south african dorper as a terminal sire breed for growth, carcass and palatability characteristics. J. Anim. Sci., 81: 368-375.
PubMed  |  

Solis, R.C., R.A. Castellanos and M.A. Velasquez, 1991. Determination of nutritional requeriments of growing hair sheep. Small Rumin. Res., 4: 115-125.
CrossRef  |  

Turner, K.E., S. Wildeus and J.R. Collins, 2003. Intake, growth and blood characteristics in pen-fed lambs of three hair sheep breeds. Am. Grasland Council Proc., 12: 359-363.

Velazquez, M.A., F.J. Quintal and A.M. Heredia, 1993. Evaluation of pelibuey and blackbelly breed sheep fertility and productivity of ewes (summary). Memories of the Annual Meeting of Livestock Research in Mexico. Guadalajara, Mexico, pp: 78.

Wildeus, S., K.E. Turner and J.R. Collins, 2007. Growth, intake, diet digestibility and nitrogen use in 3 hair sheep breeds fed alfalfa hay. Small Rumin. Res., 69: 221-227.