Invetigation of the effects alfalfa removal in the diet on growth performance and carcass characteristics in fattening Afshar male lambs

Fattening operations play an important role in the supply of animal protein, which in addition to producing more meat, the quality of meat also improves, because proper nutrition and the use of proper fattening methods accelerate the growth and improve the quality of meat. In order to achieve optimal and economical production in sheep breeding, a nutritional program must take into account the nutritional needs of livestock, the quality of food and their consumption time. However, due to the reduction of forage and pastures in Iran, the farmer is forced to use more concentrate in the diet. The aim of this study was to investigate the effects of fiber reduction and alfalfa removal on feed intake, body weight, feed conversion ratio and carcass characteristics of Afshari male lambs.

The present study was performed using 36 Afshar male lambs with a mean live weight of 32.53 ± 1.9 kg and a mean age of 93 ± 6.63 days for 90 days based on a factorial experiment based on a completely randomized 2×2 design. Experimental treatments include treatment of frist: fattening diet containing 80% concentrate and 20% forage (10% wheat straw and 10% alfalfa), second treatment: fattening diet containing 80% concentrate and 20% forage (20% wheat straw and 0% alfalfa), third treatment: fattening diet contained 90% concentrate and 10% forage (5% wheat straw and 5% alfalfa) and fourth treatment: fattening diet contained 90% concentrate and 10% forage (10% wheat straw and 0% alfalfa). The lambs were fed three times a day at 8.00, 14.00 and 20.00 for ad libitum. At the end of the feeding period, all lambs were weighed after 16 h feed deprivation and four lamb from each treatment was slaughtered. The data were analyzed using Spss21 and Excel.

There was a significant difference between different treatments in terms of weight gain. Treatment four with 90% concentrate and 0% alfalfa had the highest (300 g) and treatment one with 80% concentrate and 10% alfalfa produced the lowest daily weight gain (200 g) in lambs. With increasing concentrate and removal of alfalfa, feed consumption increased so that the highest amount was related to treatment four (1.830 g) and the lowest was related to treatment one (1.476 g). Treatment four had a numerically lower conversion ratio (6.1) compared to the other three treatments. The mean final weight of lambs, hot and cold carcass weights showed significant differences between experimental treatments.

According to the results, the removal of alfalfa did not cause any production problems in these areas. Increasing the concentrate and eliminating alfalfa in the diet increases feed intake and daily weight gain and overall higher final weight in fattening periods and also improves feed conversion ratio, growth performance and carcass percentage.