آرزو ایمان پور

The aim of this study was to investigate the effects of dietry cation-anion difference (DCAD) levels and crossbreeding on carcass characteristics of lambs. In this study, 30 Lori Bakhtiari and  first generation Lori Bakhtiari × Romanov × Pakistani lambs (50% Lori Bakhtiari, 25% Romanov, 25% Pakistani)  with an average age of 90±10 days and an average weight of 33±1.5 kg were divided into two groups of 15 lambs, each group was fed with a different level of DCAD. Carcass weight, carcass yield, viscera weight, cross-sectional area of Longissimus muscle and carcass length did not show any significant difference between purebred and crossbreds and also between diets. Crossbreeding also significantly increased the weight of valuable and salable carcass parts (P<0.05). However, according to our findings, no difference was observed in terms of weight of salable carcass parts between anionic and cationic treatmentsgenotype and DCAD did not have any significant effect on the composition of carcass fatty acids. The meat shear force of Lori Bakhtiari × Romanov × Pakistani lambs compare to Lori Bakhtiari  lambs and anionic diet compare to cationinc diet was lower (P<0.05). Lori Bakhtiari lambs had a higher mean in brightness index and Longissimus muscle redness than Lori Bakhtiari × Romanov × Pakistani lambs (P<0.05). Therefore, anionic diets and Crossbreeding can be considered as effective ways to increase the quality and crispiness of sheep meat.

Crossbreeding is a common method for exploiting genetic differences between different breeds of a species, during which offspring are usually obtained from two pure breeds through mating, which are expected to have parental traits. to improve, which includes productive traits and traits related to the health and survival of the animal that each of the parents may have superiority in one of these traits, therefore, hybridization with the aim of combining the superiority of parental traits and improving them in the results It takes place. In sheep, cross-breeding is a well-known method to improve production, including meat, milk, wool, and reproduction. Depending on the parent breeds and their purity percentage, different results may be observed in the offspring. On the other hand, food ration is a determining factor in the manifestation of the genetic power of livestock, and in the meantime, the anion-cation balance of the diet (DCAB) plays an important role by affecting the acid-base balance and homeostasis of the body. Since maintaining the acid and base balance of the body is related to the maintenance of the animal and is preferable to reproduction, lactation and growth, therefore the performance of the animal is significantly affected by the change in the acid and base balance. Therefore, the purpose of this research is to investigate the difference of diet anion-cation on performance, blood and digestion parameters and rumen parameters.

In this study, 30 Lori Bakhtiari and Lori Bakhtiari × Romanov × Pakistani lambs with an average age of 90 ± 10 days and an average weight of 32.9 ± 1.5 and 32.25 ± 1.5 kg respectively used. The lambs were placed in two racial groups in the form of a 2x2 factorial design and with two levels of anion-cation difference (DCAD) of -100 and 100 milliequivalents per kilogram of dry matter for 90 days. The whole fattening period was 84 days and anionic diet was used in the last 14 days of the period.

Based on the results of this study, dry matter consumption, weight gain and feed conversion ratio were not affected by breed. However, dry matter consumption decreased in lambs that consumed anionic diet (P<0.003). Also, blood parameters, apparent nutrient digestibility, ammonia nitrogen concentration and rumen fluid pH were not affected by diet and breed.

The results of this study indicate that the mixing of Lori Bakhtiari breed with foreign breeds has no effect on its fattening characteristics, and the use of anionic ration, along with its potential benefits, can lead to a reduction in dry matter consumption, so according to the results This research suggests that anionic or cationic rations can be used for fattening animals with various purposes without significant effect on growth performance and digestibility of nutrients as well as parameters related to rumen fluid