a. fadayifar

 In ruminants, vitamin B12 is a cofactor for two enzyme systems that are involved in many metabolic processes, such as the metabolism of carbohydrates, lipids, some amino acids, and DNA. Vitamin B12 in ruminants is synthesized by rumen bacteria or provided by dietary sources. Vitamin B12 deficiency may result in poor growth, anemia, and reduced milk production in lactating animals. In young ruminants such as newborn lambs and calves, the rumen is not fully developed for vitamin B12 synthesis until six to eight weeks of age. This means that during this period, a dietary source of vitamin B12 is necessary. Colostrum, milk, or milk replacers may be used as a source of vitamin B12 in these young ruminants. However, different factors, including nutritional deficiencies, may affect the vitamin B12 content in milk. This study aimed to investigate the effects of vitamin B12 intramuscular injection on the lactation performance of ewes and on certain blood parameters in their lambs.

 The current research was conducted at the animal husbandry station of Lorestan University.  Twenty early lactating ewes (60±0.50 kg) were selected and allocated to one of the two groups (10 ewes per group). Treatments included 1. Ewes without vitamin B12 injection (control group) and 2. Ewes with a weekly injection of vitamin B12. The first injection of vitamin B12 was given immediately after the ewes were lambed and three further injections were given per week (four injections in total). The amount of vitamin B12 injection was 1 mg intramuscularly in each injection. Milk production was recorded during the 10th, 20th, and 30th days of lactation, and the lambs were separated from their mothers for 12 hours, at which time they were weighed using a digital scale for 10 minutes. The lambs were allowed to use their mother's milk. Immediately after separation from their mother, lambs were weighed again and the difference in weight before and after milk consumption was recorded. The milk composition (including milk protein, milk fat, fat-free solids, palmitic acid, stearic acid, oleic acid, polyunsaturated fatty acids, monounsaturated fatty acids, and total unsaturated and unsaturated fatty acids) was measured with DA 7250 NIR Auto-analysis. To check the blood parameters of lambs, blood samples were taken from the jugular vein of newborn lambs at 10, 20 and 30 days of age, and from two separate tubes, one for the count of cells and one for the measurement of serum concentrations of vitamin B12 and other metabolites in the blood. Vitamin B12 concentrations were measured using the Pars Azmoun kit and the ELISA device. The data analysis was carried out with SAS statistical software (version 9.4). The comparison of the means was done using a t-test with a significance level of 0.05.

 Results showed that milk yield in the vitamin B12 group were significantly higher than that in the control group during the four weeks of the experimental period (P<0.05). This increase in milk production can be considered a response to the increased availability of plasma glucose for milk lactose production by increasing plasma vitamin B12 concentration and its vital role, such as participating in many metabolic pathways in the body and acting as an intermediary in the catabolism of some amino acids. However, the percentage of milk compounds, including milk fat, protein, solids not fat, palmitic acid, stearic acid, oleic acid, mono- and polyunsaturated fats, and saturated fats, was unaffected by the administration of vitamin B12 (P˃0.05). Blood vitamin B12 concentration was significantly higher in vitamin B12 injected ewes compared with the control group (P<0.05). There was no significant difference in growth performance, average wean weight, average birth weight, or daily weight gain of lambs born to vitamin B12-treated ewes compared to control lambs (P>0.05). Injection of vitamin B12 into pregnant ewes had no significant effect on the blood glucose, white blood cells, hemoglobin concentration, red blood cells, or hematocrit percentage of the newborn lambs (P>0.05). Vitamin B12 status in suckling lambs can be related to the rate of transfer of this vitamin through milk during lactation and through the placenta during pregnancy.

 Consequent intramuscular administration of vitamin B12 to ewes at the beginning of lactation may increase milk production and thereby increase the lambs' performance and vitamin B12 concentration in the blood.

The lack of animal feed resources and the increase in animal feed costs relative to the total production costs have created challenges in supplying society with animal protein. Therefore, correctly estimating the nutritional value of feed, especially protein sources, can be an important step in meeting the needs of livestock and reducing production costs. Protein is the most important and expensive nutrient used in ruminant diets. Using non-protein nitrogen (NPN) sources such as urea or its products can be considered a cheap alternative source in animal feeding. Iran is one of the most important urea-producing countries in the world; therefore, using urea or its slow-release products as a feed additive in animal nutrition can be beneficial. In the past years, various sources of slow-release urea have been produced and used in animal feeding. Biuret (heated urea) is one of the slow-release urea compounds, and its production cost is lower than other slow-release urea sources. Compared to urea, it has less solubility in water and is converted to ammonia in the rumen at a much slower rate. It is also less toxic than urea and has a lower negative effect on feed palatability, so it can be used to a greater extent than urea in the diet of ruminants. Biuret is very safe and it can be included in the diet of animals in an amount of 20 times higher than the toxic dose of urea. Biuret usually contains 248.5% crude protein (39.8% nitrogen content), which is a little less than urea. On the other hand, increasing the daily feeding frequency is one of the management methods that may improve the productive performance of livestock, as well as the quantity and quality of the carcass. Increasing the feed frequency may improve nitrogen retention and reduce body fat. It is believed that increasing the frequency of daily feeding will keep the feed fresh, reduce the amount of feed waste, and improve livestock performance. Therefore, this study aimed to investigate the effect of NPN source, in high-protein diets, and feeding frequency on growth performance, rumen parameters, and the activity of rumen microbial enzymes of fattening lambs.
Twenty-eight male Lori-Bakhtiari fattening lambs (age: four to five months; live weight: 36.1±3 kg) were assessed for 60 days using a 2×2 factorial experiment in a completely randomized design with four treatments and seven replications. The experimental high-protein diets (16% of DM) contained urea or biuret, which were given to the lambs in the form of a total mixed ration two or three times a day. The lambs were kept in 1×1.5 m2 individual stalls. Nutrient intake, growth performance, and ruminal parameters [on day 45 of the experiment at fasting (before morning feeding), three, and six h after feeding] including pH, ammonia and volatile fatty acid concentrations, and microbial enzyme activity were measured.
Results showed that intakes of dry matter, organic matter, crude protein, neutral detergent fiber and ether extract, final weight, and total weight gain were not affected by NPN type or feeding frequency (P<0.05). Compared to urea, lambs consuming biuret had higher average daily gain and better feed conversion ratio (P<0.05). The ruminal pH was not affected by the NPN source, feeding frequency, and their interaction (P<0.05). Rumen ammonia nitrogen concentration at three and six hours after morning feeding was significantly higher in lambs fed the diet containing urea than in biuret (P<0.05). The effect of NPN source, feeding frequency, and their interaction was not significant at 0 and six h after feeding on the ruminal concentration of total volatile fatty acids (VFA), acetate, propionate, butyrate, valerate, iso-valerate, and acetate to propionate ratio (P<0.05). However, feeding a diet containing biuret and given three times a day increased total VFA and acetate concentration at three hours post-feeding (P<0.05). The ruminal activity of carboxymethyl cellulase at 0, three, and six hours after feeding increased in animals fed biuret-containing diet compared to urea (P<0.05). However, rumen protease activity significantly increased in lambs fed a urea-containing diet than biuret-containing diet (P<0.05). Feeding three times a day increased the activity of carboxymethyl cellulase at three hours post-feeding (P<0.05). Filter paper degrading activity at three and six hours after feeding in lambs fed biuret was significantly higher than those fed urea (P<0.05). The activity of microcrystalline cellulase and α-amylase was not affected by the NPN source, feeding frequency, and their interaction (P<0.05).
Using biuret compared to the urea, in high-protein diets, and feeding diets three times a day, compared to two times a day, improved rumen fermentation parameters and performance of fattening lambs.

To investigate the milk yield and composition and some blood parameters of pregnant ewes receiving a slow-release bolus of copper, 120 Lori-Bakhtiari pregnant ewes (in their third and fourth parities with a body condition score of 3 to 3.5) were divided into three groups of 40 heads each in a completely randomized design. Treatments included: 1) control ewes (5.79 mg copper per kg of dry matter); 2) ewes receiving two milligrams of copper per day (one bolus), and 3) ewes receiving four milligrams of copper per day (tow boluses). On the first day, days 10 and 60 postpartum, blood samples were taken from the ewes. Serum copper concentration, serum ceruloplasmin concentration, and white blood cell count were significantly higher in ewes receiving one or two copper bolus than in the control group (P<0.05). Milk production, protein content, and percentage of non-fat milk solids were significantly higher in ewes receiving two copper bolus than in other treatments (P<0.05). Also, ewes receiving one copper bolus had significantly higher milk production, protein content, and percentage of non-fat milk solids than the control treatment (P<0.05). The percentage of milk fat in the control group was higher than ewes receiving two slow-release copper bolus (P<0.05). Milk copper concentration in ewes receiving one or two copper boluses was higher than in the control treatment (P<0.05). In general, both levels of copper improved milk production and some blood parameters, but the use of two boluses is recommended for higher milk production.

In this study, the effect of forage:concentrate ratio on growth performance, nutrient digestibility, and rumen parameters in male Lori Bakhtiari Lambs was investigated. A total of 27 male lambs (70 ±15 days of age, mean live weight of 26.3 ± 3.3 kg) were fattened for three months with three different levels of concentrate (55, 70, and 85%) and three different fattening period duration (first, second and third months). The apparent digestibilities of rations were measured monthly using acid-insoluble ash as an internal marker. Ruminal fluid samples were taken to determine the ruminal fermentation parameters at the end of each month. The results showed that increasing the level of concentrate improved daily weight gain and decreased feed conversion ratio (P<0.05). Increasing the diet concentrate level resulted in a decreased ratio of acetate to propionate and isobutyric acid concentrations (P<0.05). The ratio of acetate to propionate and daily weight gain decreased with increasing fattening period duration (P<0.05). In contrast, feed conversion ratio, ammonia concentration, and protozoa count increased. Interactions between diet concentrate level and fattening period duration had significant effects on final body weight, feed intake, nutrient digestibility coefficients, propionic acid concentration, and acetate:propionate ratio (P<0.05). In conclusion, the positive effects of concentrate level on performance, nutrient digestibility, and volatile fatty acid production were affected by the duration of the fattening period. Therefore, it is better to shorten the duration of the fattening period when using a high concentrate diet, and the maximum dietary concentrate level should be equal to 70% if the duration of the fattening period is increased.