تاثیر افزایش سطح مصرف جایگزین شیر بر کارآیی رشد و فراسنجه‌های خونی بره‌های شیرخوار نژاد قزل

Introduction: A large part of the income of sheep breeding is obtained through lamb production, so the proper breeding of production lambs is the most important measure to increase economic efficiency (Emsen et al. 2004). Milk production in Iranian sheep breeds is less than the need of lambs, on the other hand, milking of most Iranian ewes to produce cheese is common and the lamb is fed milk residue (Ezzatpour 1998). Milk replacer with sufficient amounts of high quality protein and suitable levels of fat, has the necessary nutrients. The result of feeding a milk substitute provides a healthy future for the whole herd. In a study of Kachi lambs, lambs raised for 56 days with ewe milk were found to grow better than lambs raised during the same period with milk replacer. But from an economic point of view, the lambs raised with alternative milk had a significant net profit compared to the group raised with ewe milk (Salahuddin 2018). In the first fourteen days of lactation, the growth of lambs largely depends on the amount of milk they consume (Simenov 2014). In the first weeks of life, as lambs have a small rumen that has not yet developed, they are unable to digest solid food, so the growth performance of the lambs depends primarily on milk consumption. A 20 percent increase in milk consumption will increase growth performance by 33 percent during lamb rearing. On the other hand, increasing growth in the first days is effective in growth after weaning, and consequently the time to reach the desired slaughter weight will be reduced (Galvani et al. 2014).
Material and Methods: To perform this experiment, 24 Ghezel suckling lambs were used in a complete randomized design with three groups of 8 heads for 60 days. The lambs were kept with the mother for three days after birth, then were randomly divided into 3 groups of 8 heads. To perform this experiment, 24 Ghezel suckling lambs were used in a complete randomized design with three groups of 8 heads for 60 days. The lambs were kept with the mother for three days after birth, then were randomly divided into 3 groups of 8 heads.Experimental treatments including group 1- daily consumed only breast milk 2 and 3- daily in addition to breast milk, respectively, consumed 5 and 10% of body weight instead of milk. From the third day, the starter and water were freely available to all lambs. Weight gain was measured weekly, feed intake and milk intake daily. Blood samples were taken at 30 and 60 days of age, The blood samples were immediately transferred to the laboratory, centrifuged (3000 rpm for 20 minutes), and then the serum was isolated and stored at -20°C. Triglyceride, cholesterol, urea nitrogen, total protein, albomin, creatin, enzymes of Lactate dehydrogenase (LDH), Alanine transaminase (ALT), Aspartate transaminase (AST) and glucose levels of the serum were measured Using the BT300 plus biochemical autoanalyzer and using Pars Azmon kit. and stool samples were taken at the end of the period (60 days of age). Data analysis was performed with SAS software. The mean compare was compared with Duncan at 5% level.
Results and discussion: The results of this study showed that daily weight gain was significantly higher in the lambs who consumed 5% of body weight intake of milk replacer in addition to breast milk. There was no significant difference between the lambs consuming 5% milk replacer and 10% milk replacer. Live weight of lambs consuming 5% milk replacer on the last day was significantly higher than control lambs, But there was no significant difference between lambs who 5 and 10% of milk replacer consumption. There was no significant difference between treatments in terms of other growth parameters. In terms of blood metabolites, the amount of total protein (Prot. Tot) was lower in the group of lambs who consumed milk replacer at 10% of body weight than the other two groups of lambs. There was no significant difference between the control group and the group consuming 5% milk replacer. Also, the amount of Aspartate Aminotransferase (AST) in the lambs who 5% milk replacer group was significantly lower than the other two groups. There was no significant difference between control lambs and lambs who consuming 10% milk replacer. There was no significant difference between the groups in other terms of blood biochemical metabolites. The results of this study showed that daily weight gain was significantly higher in the lambs who consumed 5% of body weight intake of milk replacer in addition to breast milk. There was no significant difference between the lambs consuming 5% milk replacer and 10% milk replacer. Live weight of lambs consuming 5% milk replacer on the last day was significantly higher than control lambs, But there was no significant difference between lambs who 5 and 10% of milk replacer consumption. There was no significant difference between treatments in terms of other growth parameters. In terms of blood metabolites, the amount of total protein (Prot. Tot) was lower in the group of lambs who consumed milk replacer at 10% of body weight than the other two groups of lambs. There was no significant difference between the control group and the group consuming 5% milk replacer. Also, the amount of Aspartate Aminotransferase (AST) in the lambs who 5% milk replacer group was significantly lower than the other two groups. There was no significant difference between control lambs and lambs who consuming 10% milk replacer. There was no significant difference between the groups in other terms of blood biochemical metabolites.In terms of stool parameters, Salmonella and Lactobacillus were not observed in fecal samples. The rate of Escherichia coli was higher in group lambs that consumed 5% of body weight instead of milk replacer than other groups.
Conclusions: The results of this experiment showed that the use of milk replacer in addition to breast milk at the rate of 5% of the weight of lambs could have positive effects on the growth performance of infant lambs of Ghezel breed.