Growth performance of Rahmani and Ossimi lamb breeds from birth to 12 month of age [electronic resource].

Includes references.

The aim of this study was to describe the growth performance of Rahmani and Ossimi lamb breeds through their 1st year of age. Ten newborn male lambs of each breed were allowed to suckle their dams for four months before being fed their regular ration. Lambs were fed on concentrate feed mixture in addition to Egyptian clover or its hay according to their live body weight (B W). Mineral blocks and clean water were made available throughout the daytime. Lambs were kept loose in semi shaded open yards and weighed monthly throughout the experimental period (360 day). Simultaneously to body weighing, blood samples were collected to determine 1GF 1 concentration in the peripheral blood plasma. Growth curve, relative growth rate (RGR) and average daily gain (ADG) were calculated as growth performance measurements. At days 270 and 360 of age four lambs from each breed were slaughtered to measure carcass characteristics. Breed had no effect (P>0.05) on the monthly BW and ADG within the experimental period, thus the growth curve was similar in Rahmani and Ossimi sheep. The growth curve had a concave shape up to day 240 of age, before changing to a liner shape through the rest of the experiment. Except the 1'1 phase of growth curve (birth - day 120) no significant (P< 0.01) difference in ADG was observed between the two breeds in the 2nd (day 120 - 240) and 3rd (day 240-360) phases of growth curve. GR showed an opposite trend to the growth curve, with no significant difference between the two studied breeds. Age had a significant effect on slaughter and carcass weights. Slaughter weight increased (P< 0.0003) from 31.1±I: 2.1 kg at day 270 of age to 49.3 ±I: 2.5 kg at day 360 of age, while carcass weight increased (P > 0.05) by 63.8 % during the same period averaging 15.2 ±I: 1.4 and 24.9±1: 1.7 kg for 270 and 360 day of age, respectively. Differences due to age and breed in dressing percentage and separable fat were insignificant. IGF 1 concentration was < 500 ng / ml from birth up to day 210 of age in both breeds, afterward IGF1 concentration increased to >500 ng / ml with relative higher concentration in Rahmani than Ossimi.

Summary in Arabic.

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