The growth and carcass quality of Afshari, Turkey and Mehraban lambs on different diets.

Abstract

Animal Production in Australia Vol. 15 THE GROWTH AND CARCASS QUALITY OF AFSHARI, TURKEY AND MEHRABAN LAMBS DIFFERENT DIETS Ali Nik-Khah* SUMMARY Fat-tailed lambs of the Afshari, Turkey and Mehraban breeds were given ad libitum diets containing 69 or 74% total digestible nutrients. Differences in performance between diets were small. The Afshari gained 249 g/day with a food conversion ratio of 8.3, and dressing percentage was 53.1. Corresponding results for the Turkey lambs were 194, 7.6 and 53.1, and for the Mehraban lambs 252, 6.2 and 54.7. It is concluded that locally available feeds can promote good liveweight gains in native sheep breeds. INTRODUCTION Most of the fattening lamb feeders in Iran use diets for fattening lambs containing high-cost ingredients, such as barley, alfalfa meal and cotton seed meal. Lack of information on nutritional value of low-cost local feeds makes diet formulation difficult and the genetic potential of local sheep breeds in a feedlot system is unknown. Recently the fattening performance and carcass quality of some fat-tailed lamb breeds have been investigated (Nik-Khah 1977, 1981, 1983), but reliable information on the Afshari, Turkey and Mehraban breeds is not available. In the present work, lambs of these three fat-tailed breeds were fed two diets containing different levels of total digestible nutrients. MATERIALS AND METHODS Two diets with different ingredients were formulated to have 74.2 and 69.2 percentage total digestible nutrients (TDN), which are designated diet I and II respectively (Table I). TABLE 1 Ingredients and chemical composition of the diets (percent of dry matter) *Dept. of Animal Science, University of Teheran, Karadj, Iran. 498 Animal Production in Australia Vol. 15 Rock salt. and mineral supplement (mineral block No. 1 for sheep, Cooper McDougall and Robertson Ltd.) were available ad libitum; 10 kg bone meal and 1.5 kg of a standard vitamin pre-mix were added to each tonne of the diets. Twenty Afshari, twenty-four Turkey and twenty Mehraban ram lambs, 7-8 months of age, were used in this experiment. A 2 x 3 (two diets by three breeds) factorial design was used. Lambs were fed ad libitum for 87 days, and residual feeds were weighed at 2 week intervals and at the end of the trial. All lambs were killed; hot carcass weights and their cut weights were recorded. Average daily liveweight gain (ADG) feed conversions (FCR) and dressing percentages were calculated. RESULTS The Turkey lambs (Table 2) had the lowest initial liveweight, and their ADG was less than in the other two breeds (PXO.05). However, ADG was not significantly correlated with initial weight (r= -0.07). FCR was poorest in \ the Afshari breed and best in the Mehraban. Dressing percentages did not differ between breeds, nor were there any important differences in proportionate contributions of various cuts to the whole carcass. The ADG on diet I was 240 g/day and not significantly different from the 219 g/day on diet II. Other differences between diets were small and mostly non-significant. TABLE 2 Means and standard deviations of lamb performance + Forequarter = = ++ Tallow = a, bl c Flank + brisket + flat Tallow around kidneys + Values in the same row different superscripts ribs + neck + forelegs tallow around digestive tract for breed as well as for ration with are significantly different (PXO.05) 499 Animal Production in Australia Vol. I5 DISCUSSION It is clear that cheap and locally available feeds and crop by-products such as corn silage, molasses and dried beet pulp can be used in low cost diets The that will promote high levels of productivity in native sheep breeds. sheep breeds studied performed well in feed lots, though the Turkey breed had There was no difference between the three breeds studied in the lowest ADG. carcass quality as judged by the percentage contributions of various cuts. The FCR and the dressing percentages of 53 to 55% were similar to those reported from previous studies in Iran. REFERENCES NIK-KHAH, A. (1983). Rer. J. Pajoohandeh (in press). Higher Education, Iran (English Summary). IMinistry of Culture and NIK-KHAH, A. (1981). J. Vet. Fat. Univ. Tehran, Iran. 37(4): 42 (English Summary). NIK-KHAH, A. and ASSADI-MOGHADDAM. R. (1977). Anim. Prod. 25: 393. 500