Successful pasture-based milk production systems pivot on balancing dairy cows’ feed requirements with seasonal and annual fluctuations in pasture production. In order to maximise cow production from grazing dairy systems, it is necessary to reach an efficient utilization of grazed grass for feeding cows and the de-velopment of appropriate grazing management systems designed to maximize daily pasture dry matter in-take (PDMI) per cow and per hectare, while maintaining high sward quality over the grazing season by keeping high pasture levels of crude protein, water soluble carbohydrates and digestibility of organic matter and low levels of acid and neutral detergent fibers in the swards. To maximize PDMI, cows need to con-sume plants that have characteristics that allow rapid consumption and lead to fast rates of passage through the rumen. This review considers the role of sward factors which affect the short-term feed budget of cows at pasture and, therefore, condition cow feed requirements at grazing and influence on PDMI. Furthermore, it highlights the relevance that have for the development of pasture-based milk production systems the study of the species of grasses and / or legumes that integrate the pastures, the changes on sward structure, the seasonality in grass production, the pasture chemical constituents, the sward botanical composition, the grass feeding value, the digestibility of pastures, the intensity of sward defoliation, and the importance of sward height and herbage mass in relation to maximizing PDMI. The amount of herbage consumed is the major determinant of cow production but it is yet one of the most difficult aspects of forage quality to pre-dict. In this review, three methods for PDMI calculation are presented as faecal output/diet digestibility method, sward difference method and the grazing-behaviour method. Also, three equations for PDMI esti-mation are described considering different sward and animal variables.

In this study, chemical compositions of black seed meals samples were determined. 18 male weaning Zandi lambs with an average body weight of 23.5 ±1.5 kg were used in a completely randomized design in three groups of six in individual pens. Experimental treatments were: 1) control (basal diet with 12% soybean meal and without black seed meal), 2) diet containing 6% soybean meal and 9% black seed meal and 3) diet containing 18% black seed meal and without soybean meal. The concentration of dry matter, crude protein, crude fat, NDF, ADF, ADIN, and crude ash of black seed meal samples were 97.53±0.58, 31.26±0.99, 15.16 ± 0.61, 25.95 ± 1.34, 14.2±0.80, 0.69±0.04 and 5.07 ± 0.24, respectively. Replacement of soybean meal with black seed meal in the diet of experimental lambs had no effect on final body weight, daily weight gain, feed conversion ratio, dry matter intake, dressing percentage, tail and total body fat deposition. Albumin and total protein were higher for lambs fed by diet containing 18 % black seed meal compared to other treatments (P <0.05). However, the concentration of blood triglyceride, cholesterol and urea nitrogen were not differed between experimental groups. The digestibility of dry matter, organic matter, crude fat and protein were not affect by feeding of experimental diets. It seems that black seed meal can be used in the diet of fattening lambs up to 18% without adverse effect on performance and nutrients digestibility of growing lambs.

Effects of the Monensin (Monensin sodium 10%, 350 mg/cow daily) on dry matter intake, milk production and healthy during the transition period and early lactation were determined in 360 Holstein cows. Cows were divided into groups of 2 depending on calving date. A total of 100 Holstein cows and heifers were assigned to a control group (n = 50) and administered 350 mg/cow daily of Monensin (n= 50). Cows had unlimited access to fresh water. However, no differences in dry matter intake between treatment groups were noted. Monensin significantly affected daily milk yield (p< 0. 05). Significant eff ects of Monensin supplementation were observed on disease incidence. The open days of Monensin group had a significant difference with the control group (p= 0. 0211). The Monensin group, on average, was 16 days in open days less than the control group. The conception rate in the control and Monensin groups was 43. 2% and 81. 5% respectively (p= 0. 0113). The pregnancy rate of Monensin group (34. 6%) was significantly higher than the control group (28. 4%) (p= 0. 0100). Also on the calving to first insemination distance was higher in the control group compared with Monensin (p= 0. 0317). Monensin supplementation decreased postpartum BHBA concentration. Results suggest that prepartum and postpartum administration of Monensin increase milk production and healthy and can have beneficial effects on reproductive performance during early lactation.

The objectives of this study were to determine and compare the chemical composition and ruminal degrad-ability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of ten pasture forage species dominant in the west provinces of Iran. Duplicate nylon bags of pasture samples were suspended in the rumen of four wethers for up to 96 h. The chemical composition of forages varied from 54 to 212 g/kg DM for CP, 239 to 638 g/kg DM for NDF, 190 to 378 g/kg DM for ADF and 60 to 108 g/kg DM for ash. The effective DM degradability at rumen outflow rate of 0.05/h was different (P<0.05) between forages and varied from 307 g/kg for Festuca ovina to 679 g/kg for Prangus ferulacea. The lowest CP degradability was for Festuca ovina (402 g/kg) and the highest for Bromus tomentellus (760 g/kg). The lowest NDF and the highest ADF degradability were for Hordeum bulbosum and Prangus ferulacea, respectively. The results of this study showed that the rate and extent of ruminal CP and cell wall degradation were different among forages, therefore must be considered as a main parameter in ration formulation of grazing ruminants.

In order to study the yield and water relations and osmotic adjustment in sensitive and tolerant genotypes of cutleaf medic (Medicago laciniata(L.) Mill) under drought stress, a greenhouse experiment was conducted in 2004, using a factorial arrangement in RCBD with three replications. Two genotypes of cutleaf medic, were treated in four levels of water stress include -0.1, -0.2, -1 MPa as low, medium and high stress levels respectively and Field Capacity (FC = -0.03 MPa). Results indicated that tolerant genotype had a significant superiority to sensitive genotype in most studied characteristics such as yield, Shoot and Root dry matter, Relative Water Content (RWC), Water Potential (yw),Osmotic Potential (ys), Turgor Potential (y1) and Osmotic Adjustment during medium and high water stress levels. This experiment showed that tolerant genotype had important traits; that might be possible to use these characteristics for selection of tolerant medics and recognition of mechanisms of drought resistance.

Ten male Merghoz goats with initial live weights of 29.2±1.2 kg (Mean±SE) were used to investigate the effect of natural changes in photoperiod on dry matter intake (DMI) and reproductive activity during a 365 day study. The bucks were housed in individual pens, under natural daylength condition at west of Iran, Kermanshah (34o18’ N and 47o 3’ E and 1420 m above sea level). A diet was offered with an estimated concentration of metabolizable energy and crude protein of 7.9 MJ and 98.8 g per kg dry matter (DM) respectively. Live weight, DMI, and additive daily gain (ADG) of individual animals were recorded weekly. The serum testosterone concentrations were determined in blood samples collected at monthly intervals. During the observation period, semen was collected monthly with the aid of an electro-ejaculator and examined microscopically immediately after collection. The physical parameters of semen and the semen index were recorded. The sexual behavior and testicular size of goats were assessed monthly throughout the study period. The highest DMI was observed during summer (64.3±0.9 g/kg BW0.75) and spring (62.2±2.9 g/kg BW0.75) however, the lowest was recorded in the winter season (54.0±0.9 g/kg BW0.75). The seasonal values of ADG (g/d) ranked spring > summer > winter > autumn. Bucks demonstrated the highest sexual behavior in late summer and, thereafter during autumn, using the lower (P<0.05) number of mounts per ejaculation and a higher frequency (P<0.05) to sniff, approach, and vocalize a doe with estrous status. This was coin-cided with a higher (P<0.05) level of plasma testosterone (8-10.1 ng/mL) and the best semen quality (semen index: 744-989×106/mL) and quantity (semen volume: 1.1-1.2 mL per ejaculate), higher testis length (13.3-14.7 cm) and width (6.0-6.1 cm) and scrotal circumference (32.2-35.5 cm). It is concluded that, in Merghoz bucks, the seasonal pattern of DMI and reproductive activity may be attributed to each other as well as pho-toperiod.

Background and objectives: Increasing glucose supply in the small intestine may be effective in improving the physiological status of dairy cows, and it is hypothesized that glucose supply in the small intestine increases whole body glucose supply and then improves the liver function of dairy cows during the early lactation. The aim of the present experiment is to produce a Rumen-Protected Glucose product and evaluation its effects on milk production and dry matter intake of fresh Holstein dairy cows. Materials and methods: In this study, the matrix and true encapsulation method was used to produce Rumen-Protected Glucose. Hydrogenated fat was used as the matrix for matrix encapsulation. For the true encapsulation coating method, the dextrose powder was first converted into 1-3 mm granules and then completely coated. In order to evaluate the rumen degradability of encapsulated glucose, three cows with ruminal cannula were used. In order to investigate the effects of produced Rumen-Protected Glucose, 16 fresh cows were used in a completely randomized design with two treatments and 8 cows in each treatment. The diets of both treatments were exactly the same, except that the cows in the Rumen-Protected Glucose treatment received 600 g of Rumen-Protected Glucose daily as top dressed, and the cows in the control treatment received the same amount of coating material and dextrose. Rumen-Protected Glucose was fed from day 4 to 30 after calving. The cows were kept in individual boxes and milk production and dry matter intake were recorded daily. Results: Matrix encapsulation failed to adequately protect glucose from rumen degradation. Using the true encapsulation method, a RumenProtected Glucose source with suitable degradation resistance (approximately 50% passing) and high intestinal digestibility (95% intestinal digestion) with a ratio of 70% active ingredient and 30% coating material was produced. Feeding 600 g of Rumen-Protected Glucose had no significant effect on dry matter intake (17. 76 kg/day in Rumen-Protected Glucose treatment and 17. 43 kg/day in control treatment,P>0. 48) and milk production (33. 58 kg/day in Rumen-Protected Glucose treatment and 33. 95 kg/day in control treatment,P>0. 78). The effect of time on milk production was significant in both treatments (P< 0. 005). However, the effect of time on dry matter consumption was not significant (P>0. 31). Milk fat was increased in cows that received Rumen-Protected Glucose (4. 94% in Rumen-Protected Glucose treatment and 4. 29% in the control treatment, P< 0. 033). Conclusion: A source of Rumen-Protected Glucose with suitable degradation resistance (about 50% passing) and high intestinal digestibility (95% intestinal digestion) was produced. Feeding of Rumen-Protected Glucose to fresh dairy cows improved their glycogenic status and reduced nutrient transfer for milk production.

Extended Abstract Background: Cows after calving, due to the production of milk with high fat content, which increases the energy output from the body; on the other hand, due to the less dry matter intake than what meets animal requirements, which is mainly due to metabolic and hormonal responses, cannot provide that amount of output energy from their body. All of these factors may can cause the activation of lipolysis messages for energy supply and as a result can cause metabolic disorders in this period. One of the solutions to deal with these disorders is the use of nutritional supplements, which can help prevent the occurrence of disorders during this period by reducing lipolysis messages or reducing the energy output from the body. Therefore, this study aimed to evaluate the effect of sodium acetate supplement as a lipogenic source and conjugated linoleic acid supplement as a lipolytic source on the performance of lactating cows in early lactation. Purpose of using sodium acetate supplement as a lipogenic source was to increase the animal's energy access to supply energy for intestinal tissue cells, peripheral cells, and increase de novo milk fatty acids production, which reduces the secretion of energy request messages by these tissues. On the other hand, conjugated linoleic acid supplement has a negative effect on the function of enzymes that produce milk de novo fatty acids, it causes a reduction of milk fatty acids and prevents releasing of energy through milk, which can help reduce the negative energy balance during early lactation. This study allows a comparative analysis of two distinct energy adjustment systems, each employing different mechanisms to enhance the management of negative energy balance. Methods: Twenty-four multiparous cows with an average live body weight of 618 kg and a body condition score (BCS) of 3.73, which were examined in terms of health and without any fever, retention of fetal membranes, metritis, and milk fever, five days after calving were grouped into three treatments with eight replications. The duration of the experiment was 21 days (from the 5th to the 25th day after calving). Treatments include: (1) control, (2) 100 grams per day of conjugated linoleic acid (BASF Co) supplement with 20 percent purity content of 50 percent cis-9 trans-11, 50 percent trans-10 cis-12, and (3) 300 grams per day sodium acetate supplement. Dry matter intake was measured every day before feed delivery in the morning meal. Milk production was recorded in each meal and milk compositions were measured on 5, 8, 11, 14, 17, 20, and 25 days after calving. Blood parameters including glucose, total protein, and blood urea nitrogen were evaluated on 5, 7, 14, 20, and 25 days after calving. Statistical analysis of the parameters that were measured several times during the experiment was performed using the mixed procedure, and for other parameters that were measured once during the experiment, the GLM procedure was performed using the SAS statistical software (version 9/4). Results: Dry matter intake was not affected among treatments (P = 0.31). However, dry matter intake on day 25 compared to day 5 in the control, conjugated linoleic acid and sodium acetate treatments increased by 1.64, 2.16, and 2.76 kg, respectively. Feeding sodium acetate supplement increased 19 percent daily milk production and 17 percent daily milk fat production (fat corrected milk based on 4 percent fat) compared to the control treatment (P = 0.03). Fat corrected milk based on 4 percent fat was not significantly different between conjugated linoleic acid treatment compared to other treatments (control and sodium acetate treatments; P = 0.23). Conjugated linoleic acid supplement tended to decrease milk fat percentage compared to the other two treatments (P = 0.09). There was a tended to be significant difference in the percentage of milk fat in sodium acetate treatment than in the control treatment. No significant difference was observed in the percentage and amount of daily production of other milk compounds including lactose and protein between treatments (P ˃ 0.10). In the blood parameters, only glucose index in conjugated linoleic acid treatment and sodium acetate treatment was significantly higher (P = 0.01) than control treatment. However, there was no significant difference in other blood parameters including total protein and blood urea nitrogen either in the whole period or at any measurement time. Conclusion: According to the results of this study, it seems that the conjugated linoleic acid supplement improved energy storage in the body and balanced blood glucose by reducing the energy output by reducing the percentage of milk fat. On the other hand, sodium acetate supplement by supplying energy to the tissues and its role as a precursor of milk fat, which causes a decrease in fatty acid extraction from blood by the mammary glands, and a decrease in lipolysis messages caused an increase in milk fat and an increase in blood glucose.