عنوان مقاله [English]
Introduction: Early-weaning of lambs could led to improve the efficiency and profitability of Baluchi ewesand lambs in Iranian sheep husbandry. Early weaning of lambs can stimulate growth of gastrointestinal tract,minimize weaning stress and guarantee post-weaning health. However, results on weaning age of lambs varywidely because of the effects of available feeds, feeding management and genotype.Iranian rural and nomadic herders are usually weaning their lambs when the pastures are in good condition.Reducing the duration of suckling lamb can be associated with optimal results, including sales of surplus milk ofewes and helping the herder household’s economy and entering the early weaned lambs into the feedlot systemsand breed the ewes in a well-controlled condition. The aim of this study was to determine the appropriateweaning age of Baluchi lambs to achieve the better production and economic performances as well as the higherewe's reproductive efficiency.Materials and Methods: Thirty monoparous Baluchi ewes in their second lambing with an average bodyweight of 47± 0.5 (Kg) and their lambs (15 males and 15 females with an average birth weight of 4.5 ± 0.05 Kg)were allocated to the experimental groups randomly. The lambs were left with their mothers for 3 days, in orderto consume adequate colostrum and then were divided into 3 groups according to their gender (5 males and 5females in each group) and kept in individual boxes. The experimental ewes were also kept separately inindividual boxes. These lambs were allowed to be with their mothers twice a day for 2 hours. Lambs had freeaccess to water and TMR ration including 10% Alfalfa leaves and 90% concentrate. Ewes also had free access towater and a TMR ration containing 65% alfalfa hay and 35% concentrate. The respective lambs were weaned atages of 4, 8 and 12 weeks, abruptly and fed with the above noted TMR ration. The birth weight of each lamb andthe weight of ewes were recorded at birth and until the end of the test weekly, each of the ewes and lambs wereweighed individually before morning feeding. During the experiment, every two weeks, samples were takenfrom forage, consumed concentrate and existing residues, and their dry matter and nutrient content weredetermined. The average daily weight gain, weight fluctuations, dry matter intake, milk consumption and bloodparameters at age of 12 weeks in lambs, weight fluctuations, dry matter intake at weaning time in ewes andbenefit to cost ratio were measured. Data were analyzed with Proc GLM of SAS (9.1) software in completelyrandomized design.Results and Discussion: Based on the results, early weaning of lambs at age of 4 weeks led to a significant(P<0.05) improvement in average daily weight gain, body weight, dry matter intake, reduction in milkconsumption at the end of week 12 by lambs, and improvement in body weight and dry matter intake at theweaning time by ewes. Also, the daily milk consumption of lambs showed that the production of milk decreasedgradually from the ninth week after lambing. ALP enzyme levels and IGF-1 hormone in serum of lambs weanedat age of 4 weeks were higher in comparison with the other 2 groups. In this experiment, the average cost offeed for lambs weaned at age of 4 weeks was significantly higher than the other two groups, and in the ewes, thisratio was in contrast. On the other hand, the average cost of milk consumed by lambs in the three groups wascompletely reverse the feeds and the differences between groups were significant. The cost of labor was alsosignificant in the groups due to the variability of the number of days. Average weight loss of ewes from lambingto weaning their lambs at age of 4 weeks was significantly lower than the other two groups. The average benefitfrom lamb weight gain in the group weaned at age of 4 weeks was significantly higher than the other two groups.1- PhD Student of Ruminant Nutrition, Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad,Mashhad, Iran.2 and 3- Professor of Ruminant Nutrition, Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad,Mashhad, Iran.(*- Corresponding author email: firstname.lastname@example.org)نشریه پژوهشهای علوم دامی ایران435- جلد 10 ، شماره 4، زمستان 1397 ، ص. 447Iranian Journal of Animal Science ResearchVol. 10, No. 4, Winter 2019, p. 435-447اثر سن از شیرگیری بره بر عملکرد تولیدی و اقتصادی میش و بره بلوچی 447Also, the benefit from ewe weight gain from the weaning to mating (2 weeks after weaning) was significantlyhigher in the ewes weaned their lambs at age of 4 weeks than in the other two groups. The benefit to costindicator showed weaning of lambs at age of 4 weeks could be a suitable and economical management practicein rural and nomadic situation in sheep industry.Conclusion: The obtained results revealed that early weaning of lambs (at age of 4 weeks) may be regardedas a method of lambs and ewes' management in Iranian sheep husbandry. Preparing ewes for the next pregnancyand reducing the lambing interval are the noticeable results. The offered feeds can be used efficiently, and ewe'sreadiness for the next pregnancy increased by lowering metabolic stress. Furthermore, according to the benefit tocost ratio indicator, better economical outcome could be resulted.