Thirty Holstein calves were used to evaluate the effect of starting age for alfalfa feeding on feed intake, weight gain, feed efficiency, blood and rumen metabolites concentration, and weaning age. Average birth weight of the calves was 40.6±0.77 Kg. The experimental diets were 1- diet containing starter concentrate, 2- diet containing starter concentrate+dry alfalfa (from the first day of the experiment) and 3- diet containing starter concentrate+dry alfalfa (from the day 21 of the experiment). All experimental diets were formulated to have the same levels of energy and crude protein. During the experiment, calves were fed with raw milk based on 10 % of their body weight and they were taken out three weeks after weaning. Experiment data were analyzed based upon a completely randomized design with three treatments and ten replicates per each treatment. The results showed that average daily feed intake was significantly (P<0.05) greater for calves fed diets 2 and 3 than that of diet 1 for pre- and post weaning periods as well as the whole period of the experiment. Calves fed diet 2 had significantly (P<0.05) greater average daily gain than diet 1 for pre-weaning and whole period of the experiment but no significant difference was found between diets for post-weaning period. Average weaning age for calves fed diet 2 was found to be significantly (P<0.05) lower than the calves fed diet 1. The results of this study showed that the feeding alfalfa hay to calves from the first week after birth improved feed intake and daily gain and reduced weaning age.

In this study effect of different weaning ages on feedlot performance of Farahani male lambs was studied. A number of 16 male 45, 60, 75 and 90 days-old lambs were randomly selected, weaned and fattened for 90 days. The study was carried out on a completely randomized design with four weaning weights in four replicates. Results showed that increasing weaning weight significantly increased daily feed intake, warm and cool carcass weights, but had no significant effect on total live weight, shrunk body weight and carcass shrunk percent. Thus, no difference was observed in average daily gain between 45 and 60 days ages. Mean of feed conversion ratio for 45, 60 and 75 days-old lambs was not significantly different; however, it was significantly lower than 90 days weaning weight lambs. According to no significant changes in total weight changes, shrunk body weight and carcass shrunk percent in different weaning weights and as feed conversion ratio for 45, 60 and 70 days-olds was statistically the same and better than 90 days weaning weight in addition to economical conditions which can be formed by selling the unused milk and decrease in animal aggregation in pastures, 60 days age may be suggested for weaning weight of Farahani male lambs for fattening.

The aim of this study was to investigate the effects of lamb weaning age on subsequent productive and reproductive performance of Lori-Bakhtiari ewes. 103 heads of lactating ewes with an average age of 3. 5 years were allocated to one of three treatments as: 1. weaned early 2. weaned as in traditional sheep rearing or 3-weaned late. Rams were introduced at 60 days postpartum and were remained with ewes for 3 months. Ewes that became pregnant were remained in trial. Again, rams introduced to ewes at breeding season and were remained with ewes for 6 months. The proportion of ewes that exhibit estrus, interval from lambing to first estrus and to conception, lambing interval, conception rate and number of lambs' birth per ewes exposed to the rams were recorded. Gain rate of ewes was higher for treatments 1 and 2 in first month after weaning than other months (p<0. 05). Percentage of estrus and conception rate after first parturition were significantly higher (p<0. 05) for ewes in treatment 1 than treatments 2 and 3. After first parturition, ewes in group 1, returned to estrus and conception earlier compared to 2 and 3 groups (p<0. 01). Average of 3 lambing interval was lower (p<0. 01) for group 1 ewes than groups 2 and 3. In second parturition, the number of lambs born per ewe exposed to the ram was higher (p<0. 05) for group 1 ewes than 2 and 3 groups. It was concluded that ewe's performance were improved by weaning their lambs at 60 days of age.

Introduction: Early-weaning of lambs could led to improve the efficiency and profitability of Baluchi ewes and 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 vary widely 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 of ewes and helping the herder household’ s economy and entering the early weaned lambs into the feedlot systems and breed the ewes in a well-controlled condition. The aim of this study was to determine the appropriate weaning age of Baluchi lambs to achieve the better production and economic performances as well as the higher ewe's reproductive efficiency. Materials and Methods: Thirty monoparous Baluchi ewes in their second lambing with an average body weight 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 order to consume adequate colostrum and then were divided into 3 groups according to their gender (5 males and 5 females in each group) and kept in individual boxes. The experimental ewes were also kept separately in individual boxes. These lambs were allowed to be with their mothers twice a day for 2 hours. Lambs had free access to water and TMR ration including 10% Alfalfa leaves and 90% concentrate. Ewes also had free access to water and a TMR ration containing 65% alfalfa hay and 35% concentrate. The respective lambs were weaned at ages of 4, 8 and 12 weeks, abruptly and fed with the above noted TMR ration. The birth weight of each lamb and the weight of ewes were recorded at birth and until the end of the test weekly, each of the ewes and lambs were weighed individually before morning feeding. During the experiment, every two weeks, samples were taken from forage, consumed concentrate and existing residues, and their dry matter and nutrient content were determined. The average daily weight gain, weight fluctuations, dry matter intake, milk consumption and blood parameters at age of 12 weeks in lambs, weight fluctuations, dry matter intake at weaning time in ewes and benefit to cost ratio were measured. Data were analyzed with Proc GLM of SAS (9. 1) software in completely randomized 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 milk consumption at the end of week 12 by lambs, and improvement in body weight and dry matter intake at the weaning time by ewes. Also, the daily milk consumption of lambs showed that the production of milk decreased gradually from the ninth week after lambing. ALP enzyme levels and IGF-1 hormone in serum of lambs weaned at age of 4 weeks were higher in comparison with the other 2 groups. In this experiment, the average cost of feed for lambs weaned at age of 4 weeks was significantly higher than the other two groups, and in the ewes, this ratio was in contrast. On the other hand, the average cost of milk consumed by lambs in the three groups was completely reverse the feeds and the differences between groups were significant. The cost of labor was also significant in the groups due to the variability of the number of days. Average weight loss of ewes from lambing to weaning their lambs at age of 4 weeks was significantly lower than the other two groups. The average benefit from lamb weight gain in the group weaned at age of 4 weeks was significantly higher than the other two groups. Also, the benefit from ewe weight gain from the weaning to mating (2 weeks after weaning) was significantly higher in the ewes weaned their lambs at age of 4 weeks than in the other two groups. The benefit to cost indicator showed weaning of lambs at age of 4 weeks could be a suitable and economical management practice in rural and nomadic situation in sheep industry. Conclusion: The obtained results revealed that early weaning of lambs (at age of 4 weeks) may be regarded as a method of lambs and ewes' management in Iranian sheep husbandry. Preparing ewes for the next pregnancy and reducing the lambing interval are the noticeable results. The offered feeds can be used efficiently, and ewe's readiness for the next pregnancy increased by lowering metabolic stress. Furthermore, according to the benefit to cost ratio indicator, better economical outcome could be resulted.

The present study was conducted to determine the appropriate fattening age for Afshari lambs. For this purpose, 24 male Afshari lambs were divided into four age groups (60, 90, 120, and 150 days) with average initial weights of 22. 83 kg, 27. 73 kg, 36. 30 kg, and 42. 55 kg, respectively, in a completely randomized design. The objective of this experiment, based on a previous study, was to achieve a slaughter weight of 50 kg in the shortest possible time. The results showed that the average slaughter age of the experimental groups differed significantly, with lambs fattened at 60 and 90 days of age having a lower slaughter age compared to the other groups (P < 0. 05). The effect of fattening start age on weight gain was significant, with the 90-day group showing the highest daily weight gain (333 grams) (P < 0. 05). There was a significant difference in dry matter intake among the experimental groups, with the lowest intake observed in the 60-day group (1. 31 kg), which increased with age (P < 0. 0001). As the fattening start age increased, the feed conversion ratio significantly increased, with the highest value in the 150-day group (7. 72) and the lowest in the 90-day group (4. 48) (P = 0. 0003). Neck weight differed significantly among the groups, with values of 0. 848 kg, 0. 693 kg, 0. 975 kg, and 0. 770 kg for the first, second, third, and fourth groups, respectively (P < 0. 0001). The weights of the shoulder, breast, thigh, and loin were similar among the groups and did not differ significantly. However, the weight of the tail fat was significantly higher in the 60-and 90-day groups compared to the 120-and 150-day groups (3. 063 kg and 3. 200 kg vs. 2. 085 kg and 2. 427 kg, respectively) (P = 0. 0029). Hot carcass weight and cold half-carcass weight did not differ statistically, but the highest cold carcass weight was observed in the first group (60-day start, 26. 683 kg), and the lowest was in the third group (120-day start, 23. 933 kg). The weight of meat and bone in the cold half-carcass did not differ significantly among the experimental groups. Subcutaneous fat weight was significantly lowest at 120 days and highest at 90 days (P = 0. 0152), while intermuscular fat weight in the cold half-carcass was similar among the groups (P > 0. 05). However, total fat weight, including visceral fat, in the cold half-carcass differed significantly (P = 0. 0500), being higher in the 60-and 90-day groups (5. 218 kg and 5. 300 kg, respectively) compared to the 120-day group (4. 347 kg), with the 150-day group (4. 626 kg) showing no difference from the other groups. The lowest slaughter age was observed in lambs fattened starting at 90 days, which was significant (P < 0. 05). Overall, it can be concluded that the optimal fattening start age for male Afshari lambs, considering carcass composition and cost-effectiveness, is 90 days, with a starting weight of approximately 27 kg.

The present study aimed to determine the proper weaning age of Zel lambs. For this purpose, ninety male and female lambs (average live body weight =2.57±0.41 kg) selected and were divided into three groups (each group = 30). The experimental treatments were; 1. weaning at an average age of 60 days, 2. 75 days, or 3. 90 days. The lambs were introduced to fattening program and were fed with iso-energetics and iso-nitrogenous diets until 6 months of age. The dam’s ewe of all groups enters to mating program two months after parturition and ewe lambing data contain dam’s weight, lamb’s mortality, litter size, lamb’s birth weight, and sex were recorded. Results showed that dry matter intake (DMI) and feed conversion ratio (FCR) did not affect by weaning age of lambs. The lambs that weaned at 60 days old, had higher average daily gain (ADG) at fattening period, then lambs were weaned at 75 and 90 days old, significantly. The parturition rate, prolificacy rate, lambing rate, and litter size of groups weaned at 60, 75, and 90 days of age were 88, 81, and 85; 119, 118, and 117; 104, 96, and 100; and 19, 18, and 17% respectively, and did not observed significant between the treatments. It concluded that Zel lambs weaned at 60 days old, could increase growth performance compared to elder lambs, and improves the reproductive performance of ewe.

The objective of this study was to evaluate the effects of weaning age on dry matter intake (DMI), average daily gain (ADG), feed efficiency (FE), feed cost (FC) and benefit index (BI) of Holstein calves reared un-der organic farming system. Thirty two Holstein calves were divided into two treatments: early weaning (EW) vs. late weaning (LW). Calves in the both groups were provided with whole milk at the rate of 10% body weight (BW). Calves had free access to leafy alfalfa hay from birth until the end of the experiment. Also, the EW group was provided with starter diet after weaning till 90 days of age. The daily DMI and BW at 15-day intervals were measured and FE and FC were calculated for periods. The DMI of LW and EW calves was significantly different from third period to end of experiment. Moreover, ADG of EW was higher than LW in all of periods. Except for first and second, FE was significantly different between the groups in other periods. Also, due to an increase FC for calves reared on LW compared to EW-calves group, the BI was higher in EW-calves.