Published in Scientific Papers. Series D. Animal Science., Vol. LVI
Written by Mostafa Abdel Rahman IBRAHIM
Egyptian local sheep breeds are subtropical fat-tailed ,sheep characterized by satisfactory fertility and ability to breed all year around, but have low prolificacy and growth rate. The breeding objectives were to increase the prolificacy of Ossimi and Rahmani breeds usually in the small holders and in small farm conditions. There was no formal study to set the breeding objectives. The three main breeds of sheep in Egypt are Rahmani, Ossimi and Barki. It was recommended for farmers to exchange rams and increase crossing among the three local breeds. Crossing with outside breeds such as Awassi, Cyprus and finn. The first cross was back-crossed to the local to produce1/2 Finn ¾ local from each breed group. The cross animals were mated for some generation, and involved in a selection programmed to establish a new breed type with better lamb production. The first cross ewes had a slightly better fertility conception rate than the local ewes. Crossed ram lambs performed better in pubertal age than purebred parents. Semen quality at first ejaculation had poor quality, while it was good at 80% semen motility score. Different research experiments were conducted and many additives were used to improve preserved semen quality such as dyes, Caffeine, Sugars, aromatic compounds chelating agents, antioxidants, selenium, seminal plasma, Soybean and injecting different types of Hormone. Licorice contains many photochemical which have ameliorating effects on semen quality and considered as a versatile additive. Fish oil was also used as supplementation and could improve semen quality and the conception rate and enhanced ram fertility. Effect of different dietary energy levels were also investigated on some blood and seminal constituents and semen quality of Rahmani rams. High and low dietary energy were 2615, 3138 and 2092 Kcal. ME/Kg on DM basis. Most semen physical characteristics were high LE fed rams but did not differ significantly. Effect of (50 ug IM of) GnRH injection/week on semen ejaculate characteristics in rams collected in breeding and non-breeding seasons. GnRH treatment improved libido, semen volume, sperm numbers, but not viability. More over the administration of 80 mg (Recombination Bovine somatotropin rbST), at 14 day interval starting at 2 month of age, improved growth performance puberty characteristics and semen physical characteristics of male rams. In another trail, in the hot season of the year, animals were treated with selenium (0.1 mg/DM as sodium salient) orally ,injection with melatonin 25 ug/Kg body weight daily at sunrise, and prostaglandin F2 (PG F2,3 mg/head one hour before collection of semen. Ram injected with prostaglandin F2 surpassed (p< 0.05) the control in sperm motility, Rams treated with selenium had lower significantly (P< 0.05) semen PH. Blood components in ram, were insignificant affected by selenium ,melatonin or PGF2 treatments. Research plans, programs and factors influencing the Egyptian local sheep breeds fertility of stored semen and methods used for improvements are discussed.
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