methionine

Choline and methionine are crucial nutrients for livestock as they provide methyl groups. The relationship between these two nutrients is intricate, with varying opinions on their interdependence. Methionine is often a limiting amino acid in dairy diets and its metabolism is linked to that of choline and betaine. Choline as an alternative to methionine, can act as a precursor to phosphatidylcholine, which is important for dairy cows around calving time. Furthermore, choline and betaine impact methionine requirements and methionine can affect choline metabolism. Given that limited study and experimentation have been conducted so far to investigate the effects of unprotected methionine and choline on calves, this research aimed to examine the impact of unprotected methionine and choline on feed intake, growth, digestibility, fecal score, blood metabolites, and feed behavior of pre-weaned calves. The expected hypothesis of the study was the significant effect of utilizing unprotected methionine and choline on feed intake, growth, digestibility, fecal score, blood metabolites, and feeding behavior of pre-weaned calves due to their mono-gastric nature and lack of rumen development.

A total number of 32 Simmental male suckling calves, aged approximately one month old with an initial weight of 44±2.1 kg, were used in this study. The experimental treatments included: 1) a basal diet without choline and methionine (control), 2) the basal diet with three grams of methionine, 3) the basal diet with three grams of choline, and 4) the basal diet with 1.5 grams of methionine and 1.5 grams of choline per head per day. The calves were randomly assigned to the experimental treatments in a completely randomized design with eight replications. The study lasted for 45 days, including a 7-day adaptation period. Blood glucose, cholesterol, triglycerides, and urea nitrogen levels were measured on the last day of the study, four hours after morning feeding, to evaluate the metabolic profile of the animals. Additionally, feed consumption behavior was visually observed for 24 hours on the last day of the study to calculate the animal's rumination, eating, chewing, and resting time. To determine the digestibility of dry matter, samples were collected from feed and feces during the last three days of the experiment using the acid-insoluble ash internal indicator method. Stool consistency was scored for all of the calves as an indicator of animal health.

The inclusion of three grams of methionine in the experimental treatments resulted in a decrease in dry matter intake, and when methionine and choline were added, it increased the daily weight gain of the animals (P<0.05). However, the treatments did not have a significant effect on the feed conversion ratio (P>0.05). The results of other studies showed that the addition of choline did not have a significant effect on the amount of dry matter consumed, daily weight gain, and feed conversion ratio of Holstein bull calves. Consistent with the results of the present study, no improvement was observed in the feed efficiency of steers with the addition of a protected choline supplement, and no effect was observed on dry matter intake. The treatments did not have a significant impact on dry matter digestibility, stool consistency, blood glucose, cholesterol, triglyceride, and urea nitrogen (P>0.05). In agreement with the results of the present study, the digestibility of dry matter and organic matter in steers was not affected by choline. Researchers reported that the use of protected biocholine and methionine did not have a significant effect on the digestibility of dry matter in calves. Also, it was observed that the use of choline did not have a significant effect on the digestibility of dry matter in sheep and pre-weaned calves. Researchers have reported that the use of protected methionine and choline did not have a significant effect on the levels of glucose and triglycerides in the blood of dairy cows before calving. In another study, the urea nitrogen in the blood of dairy cows was not affected by methionine and choline. Additionally, the experimental treatments did not affect feed consumption behavior (P>0.05).

Feeding unprotected choline and methionine did not have a significant effect on glucose, cholesterol, triglycerides, blood urea nitrogen, digestibility of dry matter, fecal consistency score, and feeding behavior. However, the use of methionine improved dry matter intake and daily weight gain. Feeding Simmental calves with three grams of methionine per day is recommended to improve dry matter intake and daily weight gain, although it does not significantly affect the feed conversion ratio.

This experiment was conducted to investigate the different levels of methionine in Standard and Low-protein Diets on Performance, Carcass Traits, blood metabolite and histology Parameters of growing Female Japanese Quails in a completely randomized design with 2 × 3 factorial arrangement. This experiment was consisted of two levels of protein (recommended level (NRC1994) and 10% higher than recommended level) with three levels of methionine (NRC recommended, 10% lower and 10% higher than recommended). This study, conducted with total of 480, 14-d quails that consisted of 6 treatments and 4 replicates and each replicate consisted of 20 chicks. The raising period for performance evaluation ranged from 14 to 35 days. All experimental diets were differed at crude protein and methionine, but other nutrients was in amount that recommended by NRC 1994. The results showed that interaction of crude protein and methionine had significant effect on body weight at 28, 35 days of age (P<0.05). Protein level had significant effect on total FCR (P<0.05), so lower FCR was resulted from chicks with 100 recommended level and also methionine level was significantly affect total fcr, so the %110 methionine level had better FCR than other levels . Experimental treatments had no significant effect on carcass constitutes and Blood metabolite, in female quails. Villus area, villus height to crypt depth ratio, and villus height was affected significantly by interaction of CP and Met (P<0.05). In conclusion, NRC 1994 recommended CP diet with 110 % Met level can improve quail production traits ,

The objective of this study was to investigate the effect of decreasing dietary protein content with supplementing protected methionine (pMet) andlysine (pLys) on intake, milk yield, metabolic status, and apparent digestibility of nutrients in Holstein fresh cows. Immediately after calving, 16 cowswith the similar BCS and parity were randomly assigned to two treatments. Experimental diets provided equal amounts of lysine (132 to 133 g/d) andmethionine (40 to 43 g/d). The treatments were: a diet containing 18.35 % CP without supplementing pMet and pLys (HP); and a diet containing16.45 % CP with supplementing rumen-protected amino acids (LPML). Individual dry matter intake and milk yield were recorded daily during freshperiod. Blood samples were collected at 0, 3, 7, 14 and 21 d after calving to determine the serum concentrations of mineral and metabolites. Feedintake was not affected by experimental diets but milk yield was higher for HP cows than cows in LPML (P < 0.01). The yield of milk protein,lactose, fat and concentration of milk urea nitrogen (MUN) were higher in HP cows compared to LPML (P < 0.05). Compared to HP cows, cows inLPML had lower blood urea nitrogen (BUN) and higher serum concentrations of total protein and globulin (P < 0.01). Based on the results of thepresent study, reducing dietary protein content while maintaining the supply of limiting amino acids decreased lactational performance and feedefficiency of Holstein fresh cows.

This research aimed to investigate the effect of different dietary methionine levels on performance, carcass characteristics, energy and protein efficiencies, breast muscle nutrients, and some blood indices in Japanese quails during 11-24 days of age. This experiment was conducted in a completely randomized design during 14 days with 490 quail chicks in seven treatments and five replicates each (14 chicks in each replicate). The experimental diets were the NRC requirement of methionine for quail (0.5 percent), three methionine levels of 7.5, 15, and 22.5 percent lower than that of NRC requirement level (0.4625, 0.425, and 0.3875%, respectively), and three levels higher than that of NRC requirement level (0.5375, 0.575 and 0.6125%, respectively). The results showed that consumption of 0.575% methionine level caused the highest weight gain and lowest feed conversion ratio (linear and quadratic responses). The breast protein content was linearly increased by increasing the methionine level to 0.5%. Consumption of 0.6125% methionine (the highest methionine level) caused the highest relative thigh weight (linear and quadratic responses). The best energy and protein efficiencies were indicated by consumption of 0.575% methionine (linear and quadratic responses). The methionine requirement for optimal weight gain, feed conversion ratio, and energy and protein efficiencies were 0.569, 0.578, 0.54, and 0.35% according to the quadratic broken line. In total, the level of 0.569% was determined for methionine requirement based on the cumulative response of weight gain, feed conversion ratio, and energy and protein efficiencies.

Lamb fatteners receive less benefit due to unawareness regarding the suitable methods of fattenering. As it is conventional in broiler breeding, the diet of pre-starter contains high levels of protein and energy, which is specified to freshly hatched chicks and it decreases the number of days between hatching and slaughter day every year. Therefore, the same method can be tested in newborn lambs, meaning that the lamb receives the whole mother's milk and the initial diet, which is referred to creep feeds. The creep feed contains at least 15 percent crude protein and breeding lambs immediately after birth, with receiving a diet either rich in metabolizable protein or low metabolizable protein with a lysine amino acid and a rumen-protected methionine. This may be substituted with the conventional method of feeding lamb via whole mother's milk, alfalfa and Rangeland forage and then, fed in an intensive system under Iranian conditions. The present research was designed and conducted to economically compare the conventional method with creep feeding method in Afshari lambs, and to investigate the possibility of shortening the time from birth to slaughter. Production of meat with high quality and quantity without increasing the number of livestock and gaining an appropriate profit in the short term is one of the main goals of the fattening industry. The cost of livestock feeds supply is about 65-70% of the costs of raising and maintaining. If these costs are reduced in a period of fattening, in addition to producing meat with a good quantity and quality, more income will be also earned by the livestock owner (Farzad 1996; Talebi and Edriss 1999; Mousavi et al. 2005, 2011). Improving human living standards, reducing physical activity and changing food habits have led to a reduction in tail fat consumption and a rise in demand for meat. Also, if low-fat and low-fat sheep are produced, improving the nutritional efficiency will increase the economic efficiency of fattening units (Talebi 1998), so that the livestock fed in the lower ages will have better food efficiency (Hasanpour 1965; Mousavi et al. 2005, 2011). Choosing the appropriate fattening method will reduce the starting age, longevity and cost of rearing lamb and leaving livestock out of the pasture, which will lead to a rapid return of payments and improvement of investment in the sheep industry, reduced overgrazing and preventing soil erosion and flood damage. Due to the advancement of ruminant nutrition science in recent years, it is possible to start fattenning at a young age. Then, the use of creeping rations is associated with a change in the composition of the diet, especially metabolizable protein; as a result, growth, daily weight gain, and feed efficiency are increased and carcass compositions may have more meat. The goal of this study was to select an appropriate Fattening system that would provide greater economic returns through a higher percentage of meat, less feed, and reduced lamb's longevity. Choosing the appropriate procedure of feedlot and deliver the lambs to slaughter weight in the possible shortest time reduces the cost of livestock and There was an additional livestock departure from the pasture. 51 male lambs of Afshari were used in an unbalanced completely randomized design with 4 treatments included: treatment 1: Milk + alfalfa + pasture (conventional control without fattening as semi-intensive farming or CONT-UF ), treatment 2: Milk + alfalfa + pasture then get a fattening diet ( conventional control with fattening as semi-intensive farming or CONT-F ), treatment 3: milk + creep feeding ( included high protein metabolism as intensive farming or HMP), and treatment 4: milk + creep feeding (including low protein metabolism with lysine and methionine rumen protected as intensive farming or LMP +LMRP). The effect of creep feeding on average daily gain of lambs was significant (p=0.0001), (Table 2) Which was consistent with the results of others (Karim et al. 2001; Moriel and Arthington 2013; Yiakoulaki et al. 2007; Lardy and Maddock 2007). The reason for the increase in daily weight gain at an early age is due to the higher growth rate of the animal early in life, which is justified by growth curves that are consistent with the goal of experimenting with early onset of slaughter and slaughter at an early age. The low daily gain was due to the non-fattening control treatment, but it was fattened in the control treatment because fattening started at 5 months of age and the daily gain was lower at high ages. Reduced protein intake and amino acids intake and no effect on body weight changes were observed in creep diets, whereas in Abdelrahman and Hunaiti (2007), Purchas et al (1998) and Yousefian et al (2013) studies, weight gain was observed but in the experiment, Heydari et al (2014) reduced yield. Dry matter intake among the treatments was statistically significant and the highest rate was found in the fattening control (p=0.0001), (Table 2) Which is consistent with the results of other researchers (Eilami 1995; Eilami 2005; Kianzad 1993). The amount of dry matter consumed depends on the body weight of the animal as the age of the animal increases and consequently body weight increases feed intake in this experiment as slaughter age varies so the amount of consumption depends on the life of the animal and in creep treatments due to nutrient availability. As well as increased feed efficiency at an early age, the amount of dry matter consumed was low, whereas this was not the case for the control treatments because the dry matter consumed before the beginning of the feed was used to maintain low weight gain. FCR in the fattening and non-fattening controls increased significantly and recorded the highest amount in the fattened control (p=0.0001), (Table 2) This is in agreement with the results of other researchers (Eilami 1995; Eilami 2005; Kianzad 1993). The conversion factor is a function of the amount of feed consumed to increase body weight, which is an increase in the feed conversion ratio with increasing age of the animal due to the type of animal body stored so that as the age of the animal increases, the amount of fat stored in the protein increases and the cost of increasing each gram of fat tissue increases. Compared to the cost of increasing every gram of muscle tissue, this increases the conversion factor. Carcass effiency was reduced significantly in the non-fattening control (p=0.0001), (Table 3) While in the creep treatments, even at a young age, carcass yield had a higher number, indicating greater growth of organs, but no significant difference was observed between creep and fattening treatments. The greatest benefit was observed in LMP + LMRP treatment and loss was observed in CONT-F treatment (P = 0.0001), (Table 4) Since the fattened control treatment had a life span of 260 days and the other treatments reached the kill weight in the shortest time. Baesd on the economic calculations, LMP+LMRP treatment was determined as a better method for finishing lambs.

Heat stress is considered as one of the most important stressors accompanied by economic losses to the poultry industry. It causes reductions in weight gain and a series of metabolic disorders in broiler farms. Methionine is one of the most limiting amino acids, playing a crucial role in body protein synthesis, and therefore it would be beneficial to spare its function as a methyl donor. Broilers can utilize the isomers and analogs of methionine for protein synthesis, because of the unique enzymatic pathways to convert methionine isomers to L-methionine in the liver and kidney. Betaine is a common term for trimethylglycine, a substrate for betaine-homocysteine methyl transferase in the liver and kidney that acts as a methyl donor during methionine synthesis from homocysteine. The present study aimed to evaluate the effects of supplemental methionine sources and betaine replacement on growth performance and carcass characteristics of normal and heat-stressed broiler chickens.  This experiment was carried out in two adjoining poultry houses (n=1200, Ross 308). The experiment was designed in a 2 (Met sources)×2 (temperature)×3(Met levels)×2 (betaine levels) split-plot form, with two poultry houses (60 pens each) as the main plot and 12 different diets as the subplot, with 5 replicates of 10 birds each. Mash corn-soybean meal basal diets were prepared for starter (1–10 d), grower (11–24 d) and finisher (25–42 d) periods to meet 2014 Ross 308 nutrient recommendations, except for Met. Methionine levels in basal diets were adjusted at 30% lower than recommendation. They were increased to recommendation and/or 30% more than recommendation by supplementing DL-Met and/or L-Met. Betaine was substituted with 30% of supplemental DL-Met and/or L-Met. The betaine levels were calculated according to a molecular weight basis. Betaine contains about 3.75 times the methyl groups compared with Met. The temperature of both houses was set to thermal comfort temperature until 10 d of age. Then, the temperature of one house was gradually decreased by approximately 3°C/week until reached to the basal temperature (23°C) at d 28 and remained constant thereafter. In the other house, the temperature was gradually increased to 32°C between 0800 and 0930 and this high temperature was maintained for 6 h (until 1530). After that, the temperature was gradually decreased to the basal level by 1700. Body weight gain (WG) and feed consumption (FI) were recorded periodically, and feed conversion ratio (FCR) was calculated for each period by dividing feed intake by weight gain taking into account the mortality weights. Feed intake in broilers fed diet with 30% higher methionine was significantly lower than the other two groups. Body weight gain was higher in birds fed diets with recommended or 30% higher than recommended methionine compare to those fed diets with 30% less than recommended. It is tendentiously due to the inciting effect of Met on growth by means of growth factors and its influence on protein synthesis and breakdown. FCR in diet of 30% less than recommended methionine and containing L-methionine was significantly improved in comparison to diet containing DL-methionine in the same level. Chicks required 138 or 141 units of DL-methionine to achieve the same daily weight gain and G: F of birds receiving 100 units of L-methionine. Also, a number of studies have shown that the effectiveness of DL-methionine is similar to that of L-methionine in chicks. In this study, replacing of betaine with 30% of supplemental methionine, showed no significant differences on performance parameters, which implies the sparing effect of betaine for methionine. It appears that methionine and betaine supplementation to slightly methionine deficient broiler diets could result in an equivalent growth response and that methionine could be slightly spared by betaine. The production efficiency factor improved by elevated levels of DL-methionine, but no difference was found between highest level of methionine and its standard level. Carcass yield, breast yield and tights yield had significant increase in birds fed diets with recommended or 30% less than recommended methionine. This may be due to increased muscle protein deposition induced by methionine. Birds fed diets with recommended or 30% less than recommended methionine had the lowest and highest percentage of abdominal fat, respectively. The improvement in carcass lean percentage may be attributed to a higher availability of recommended and cystine for protein deposition. This is because an enhanced utilization of dietary amino acids for protein synthesis may result in fewer amino acids available for deamination and eventual synthesis of adipose tissue. In the present study, replacing betaine with 30% methionine showed similar responses to methionine. Changes in hormone levels and growth factors involved in the regulation of fat synthesis and degradation, as well as lower activities of lipogenic enzymes, have been observed following dietary betaine supplementation. Heat stress reduced performance and carcass yield and increased mortality and abdominal fat content. HS disturbs the intestinal flora balance and thereby diminishes nutrient digestibility and absorption. These results indicated that replacing 30% of methionine with betaine resulted same result in broiler performance. The use of methionine below the recommended level, reduces performance in broiler chickens. L-methionine appears to be more effective methionine source in improving the FCR than DL-methionine.

This experiment was conducted to evaluate the effects of dietary levels of crude protein, methionine and betaine on performance and carcass characteristics of broiler chickens. A total of 640 one-day-old broiler chicks from Ross 308 strain were used. Each pen (1.5 ×1.5m) was assumed as experimental unit and was included 20 male and female chicks. The experiment was conducted based on completely randomized design as a 2×2×2 factorial arrangement. The chicks were reared on the basis of regular brooding procedures until 7 days of age and then were fed with diets containing 2 levels of crude protein (high and medium), 2 levels of methionine (high and medium) and 2 levels of betaine (0 and 0.08%) from 7 to 42 days of age. All experimental diets were prepared isocaloric. Average daily feed intake, average daily weight gain and feed conversion ratio was measured weekly. At day 42 of age, one male bird from each pen was selected and slaughtered for carcass analysis. Results of this experiment showed that none of treatments had a significant effect on feed intake in 7 to 42 days of age (P> 0.05). Betaine fed groups showed more daily feed consumption in compare to other groups but this effect was only significant during 14-21 days of age (P

The effects of two sources of organic zinc on performance and immune responses of broiler chickens were evaluated by using seven-hundred and fifty day-old Arian broiler chickens which randomly allocated in 30 experimental units in a completely randomized design as a 2×3 factorial with two sources of organic zinc (zinc- methionine and zinc- glycine) and three levels of dietary zinc (40, 80 and 120 mg/kg). During the experiment, live body weight (LBW), feed intake (FI) and feed conversion ratio (FCR) were measured weekly. At the end of the experiment (age 42d) two birds from each replicate were bleed and total antibody titer against Sheep Red Blood Cell (SRBC), antibody titer against Newcastle Disease virus (ND) and differential count of white blood cells (WBC) were measured. Dietary inclusion of zinc-methionine improved LBW (day 42), FI (days 0-28) and FCR (days 0-14) in comparison with zinc- glycine (P

The effects of replacing 0, 15 and 20 of corn by percent oak acorn (OA), in diets contacting recommended and twice recommended level of methionine by NRC (1994) on performance of broilers were investigated. 528 one-day-old Cobb 500 broiler chicks in a 2×3 factorial arrangement based on completely randomized design with four replicates of 22 chicks were used. Chicks fed with diets containing 15 and 20 percent OA had lower body weight gain and higher feed conversion ratio compared to those fed with diet without OA, in all experimental periods (P

This study was conducted to clarify the effects of in-Ovo injection of pyridoxine, methionine, and their combination on broiler breeder eggs hatchability, chick weight, and production attributes. On day 18 of incubation, 400 Ross 308 breeder fertile eggs were weighted and allocated to 5 treatments with 4 replicates of 20 eggs each, in a CRD design. The treatments included: negative control (no injection), positive control (injection of 0.1 ml of Sodium chloride), injection 0.5 ml of pyridoxine (B6), injection of 0.5 ml methionine (Met), injection of 0.5 ml pyridoxine and methionine (B6+Met). The solutions were injected into the amniotic fluid of eggs. Upon hatch, hatchling chicks counted, weighted and then transferred to farm and reared to 42 d of age. Feed intake, weight gain and feed efficiency ratio were recorded.The results of this study indicated that, hatchability, day-old chick weight and hatched chick body weight / Initial egg weightshowed no significant differences (P>0.05). No significant differences was obtained for feed intake, except at 0-3 weeks, while compared to PC, B6+ Met, showed significant differences (P<0.05). Conclusion was that, under the condition of present study, injection of vitamin pyridoxine, methionine and their combination had no significant effects on hatchability and day old chick, despite feed reduction in B6 and Met compared to PC, no significant differences were observed in weight gain and feed conversion ratio, probably due to better efficiency of feed in chicken hatched from treated eggs.

Central composite design (CCD; 5 levels and 3 factors) and response surface regression (RSREG) were used to evaluate the response of broiler chicks [average daily gain (ADG), feed conversion ratio (FCR) and feed intake (FI)] to dietary requirements of lysine (Lys), methionine (Met) and threonine (Thr). A total of 60 battery brooder units of 6 birds each were assigned to 15 diets in 3 replication from 2 to 16 d of age. Analysis of variance showed that the overall effects of of Lys, Met and Thr had significant effects on ADG, FCR, however only the effect of Thr on FI was significant (p < 0.05). Also, it has shown that the linear and non-linear effects of those amino acids ADG and FCR was significant (p < 0.05). The interaction among those variables on ADG was significant (p < 0.05) but on FCR was not significant. For both ADG and FCR, the goodness of fit in terms of R2 corresponding to RSM models showed a substantially moderate (ADG model: R2 = 0.51; FCR model: R2 = 0.57) to none (FI model: R2 = 0.29) accuracy. The results of this study revealed that the platform of RSM model (for conducting group amino acid requirements) may be used to describe the inter-relationships (or interactions) between multiple amino acid contents and broiler performance to achieve the optimal target (high performance and low cost). In other words, RSM was also employed to optimize multiple variables to predict the best performance conditions with a minimum number of experiments

This experiment was conducted to examine the effect of different levels of protein (13 and 15%) and methionine (0.25, 0.30 and 0.35%) on performance and some egg indices in the late laying period of layer hens. Ninety six leghorn 80 weeks W-36 layers were used as a 2×3 factorial arrangement based on the completely randomized design. The results have shown that as methionine level was increased, the production percentage and egg weight were increased (P<0.05). Different levels of protein had no significant (P>0.05) effect on the production percentage and egg weight. Treatment effect on the production percentage and egg weight was significant (P<0.05), as birds fed diet containing 15% protein and 0.35% methionine had the highest production percentage and egg weight. Experimental treatments had no significant (P>0.05) effect on other parametes (cracked and soft eggs sell, yolk and albumen indices, egg area, egg weight to area ratio, yolk color, haugh unit, egg content and egg shap index). It can be concluded that the best levels of protein and methionine for egg production in the late laying period of laying hens are 15 and 0.35%, respectively.

The current study intends to analyze the effects of methionine on the ovulation of guinea pigs. 60 guinea pigs were given 4 different treatments in a completely randomize design. The treatments contained 0، 2، 4 and 6 percent of methionine per kg as fed. After two weeks as adaptation period، the four different treatments were given to the animals for two estrus cycle. After synchronization which was achieved through the inter muscular injection of PGF2a analog (cloroprostonal). 6ml/kg of cloroprostonal was injected twice in an eleven-day interval. At the end of experiment guinea pigs were slaughtered and the numbers of mature follicles were calculated by loop microscopy. The result shown that، the number of mature follicle increased as the amount of methionine in the diet rased. The Duncan`s test showed a significant relationship between the number of follicle in the right and left ovary with the higher amount of methionine (P<0. 05) and didn’t reflect a significant relationship between weight of two ovary and the amount of methionine. It seems that if the amount of methionine increases in the diet، the ovulation will also increase regardless of the ovary and body weight.

This experiment was conducted to evaluate the effects of chromium supplementation on performance, blood parameters, lipid oxidation of longissimusdorsi muscle (LDM) and tissue chromium in Mahabadi goat kids. Thirty-two male kids (average initial BW of 22 ± 2 kg, 4-5mo) were used in a completely randomized design with four treatments: 1) control (without Cr suppl.), 2) 0.5 mg Cr suppl., 3) 1 mg Cr suppl. and 4) 1.5 mg Cr suppl. as Cr-Met/animal/d. Diets were the same and experimental period was 94 days. Animals were kept in individual pens with self-mangers. Kids were weighed at 21 day intervals and slaughtered at the end of the trial. Dry matter intake and average daily gain were not affected by the chromium supplementation but, feed conversion ratio (FCR) improved in the 1.5 mg Cr/d. Maximum blood glucose concentration during an epinephrine challenge test decreased in the 1.5 mg Cr/d group. However, blood insulin and cortisol remained unaffected. TBARs values of the LDM significantly increased as their storage time increased from 1 to 2 months (P<0.05). It was also found that increasing dietary chromium supplementation, especially 1.5 mg Cr/animal/d, significantly decreased lipid oxidation and TBARs value of LDM after 2 months storage (P<0.05). On the first month of storage, dietary Cr supplement not significantly tended to decrease lipid oxidation of LDM (P<0.1). Chromium contents in plasma, liver, kidney and LDM increased significantly with the addition of Cr-Met in diet (P<0.05). The results of this experiment showed that supplemental Cr improved performance, decreased TBARs value of LDM and increased chromium contents in blood and tissues of Mahabadi goat kids.

In a completely randomized design، the effects of different levels of supplemental DL-methionine in starter diet of broilers on performance، humeral immunity، carcass efficiency and heamatological indices were investigated. Two hundred and eighty eight day-old Ross 308 hybrid chicks were divided into 16 groups (4 treatments، 4 replicates and 18 chicks per replicate). Dietary treatments were four levels of sulfur amino acids (SAA)، (0. 7، 0. 8(control diet based on NRC)، 0. 9 and 1. 0%). At day of 21 old، feed intake and weight gain of 0. 7% SAA group، were significantly lower than other three groups (36. 72 vs. 40. 07، 41. 52 and 39. 92 g/chick/ day، for feed intake; 21. 62 vs. 24. 41، 25. 59 and 25. 96 g/chick/ day، for weight gain، respectively) (p≥0. 05). Chicks consuming diet with highest level of SAA had lower feed conversion rate than first group (1. 54 vs. 1. 70 g/g، respectively) (p≥0. 05). Antibody titer (HI) against Newcastle Disease Virus (NDV) in chicks of third and fourth groups were higher (p≥0. 05) than second group and second group was higher (p≥0. 05) than first group (4. 5، 4. 0، 2. 5 and 1. 0، respectively). Chicks consuming diet with 0. 9% of SAA، in starter، had lower abdominal fat than first group at day of 42 old (1. 58% vs. 2. 5%، respectively) (p≥0. 05). The results of this investigation indicated that for developing of humeral immunity of broilers and lowering of abdominal fat، quantity of SAA in starter diet must increase than NRC (1994) recommendation.

To investigate the effects of different levels of roasted fullfat soybean and methionine on performance of broilers،an experiment was conducted in a completely randomized design on 312day-old male broilers Ross strain with 6 treatments (three levels roasted soybean 0،8،12 and two levels of DL-methionine 100 and 110% Ross(2007) recommendation)and 4 replications (13broilers per replicate). The experimental period was 42 days (starter 0-10، grower11-24، finisher25-42) and diets were provided isocaloric and isonitrogenous. All birds were fed ad libitum. The same management system was adopted for all birds، reared in 24 floor pens in a poultry house. Feed intake، weight gain and FCR were measured at the end of every period. At the end of production period، broilers were weighed; blood samples (5cc) were obtained and slaughtered. The results showed that addition of roasted fullfat soybean to diet had significantly affected weight gain، FCR and feed intake in the finisher period (p)

In the study presented here, the scope of a reparameterized monomolecular model was extended in growing young male chicks to provide an estimate of their lysine and methionine requirements for maintenance and growth. The equation was used with the NLMixed procedure of SAS to estimate parameters and combine them to determine other biological indicators. A number of criteria were used to evaluate general goodness of fit of the model, including model behavior, biologically meaningful parameter estimates and statistical performance. The estimated maintenance requirements and the determined values of lysine and methionine requirements for protein accretion were in good agreement with values reported previously by other researchers. Average efficiency of recovering lysine and methionine were greatest at low intakes and decreased as intakes increased. In conclusion, results presented here showed the applicability of the monomolecular equation to predict the magnitude and direction of responses of growing young broilers to dietary lysine and methionine intake without making any initial assumptions.

This study was conducted to investigate, effects of diets supplemented with methionine and/or garlic powder on performance and carcass composition of broiler chickens. 540 day-old broiler chicks in a completely randomized design with 3 3 factorial arrangement (9 treatments and 4 replication) were fed with different levels of methionine including basal diet (without methionine addition), diet containing methionine recommended by NRC as well as 135% NRC, and different levels of antibiotic. Chicken in 52 days of age were slaughtered and their carcass were analyzed. Addition of methionine at 135% NRC level in diets increased breasts muscle weight(P<0.01). Diets supplemented with garlic powder resulted in significantly high breast muscle weight as compared with negative control(P<0.05). Diets supplemented with Garlic powder leads to significant decrease in abdominal fat pad.Methionine antibiotic interaction in BD+Met+GAR showed highest and BD+GAR appeared with lowest abdominal fat pad (P<0.05).Methionine antibiotic interaction resulted as lowest tight muscle weight (P<0.05). In conclusion results from present study demonstrated that beneficial effects of methionine and/or garlic powder for improvement of broiler carcass quality.