蛋氨酸锌在奶牛生产中的应用

蛋氨酸螯合锌是一种新型有机矿物元素添加剂,被称为第3代微量元素添加剂;由于其稳定性好、生物效价高、易消化吸收、抗干扰性强等特点,迅速成为动物营养研究的热点,并在各种动物生产中得到广泛应用。作者就蛋氨酸锌在奶牛实际生产中的相关应用研究进行综述,并对其应用前景进行探讨。     

Effects of supplemental d-methionine in comparison to l-methionine on nitrogen retention,gut morphology,antioxidant status,and mRNA abundance of amino acid transporters in weanling pigs

An N-balance experiment was conducted to test the hypothesis that d-Methionine (d-Met) has the same bioavailability and efficacy as l-Methionine (l-Met) when fed to weanling pigs. A Met-deficient basal diet containing 0.24% standardized ileal digestible (SID) Met was formulated. Six additional diets were formulated by adding 0.036%, 0.072%, or 0.108% d-Met or l-Met to the basal diet, and these diets, therefore, contained 77%, 87%, or 97% of the requirement for SID Met. Fifty-six barrows (10.53 ± 1.17 kg) were housed in metabolism crates and allotted to the seven diets with eight replicate pigs per diet. Feces and urine were collected quantitatively with 7-d adaptation and 5-d collection periods. Blood and tissue samples from pigs fed the basal diet and pigs fed diets containing 0.108% supplemental Met were collected on the last day. Results indicated that N retention (%) linearly increased (P < 0.01) as supplemental d-Met or l-Met increased in diets. Based on N retention (%) as a response, the linear slope-ratio regression estimated the bioavailability of d-Met relative to l-Met to be 101% (95% confidence interval: 57%–146%). The villus height and crypt depth in the jejunum were not affected by the Met level or Met source. Total antioxidant capacity or thiobarbituric acid reactive substance concentrations in plasma or tissue samples from pigs fed the control diet or diets containing 0.108% supplemental d-Met or l-Met were not different. Abundance of mRNA for some AA transporters analyzed in intestinal mucosa of pigs also did not differ. Therefore, it is concluded that d-Met and l-Met are equally bioavailable for weanling pigs.     

Lipid peroxidation,protein oxidant and antioxidant status of muscle and serum for juvenile Jian carp (Cyprinus carpio var. Jian) fed grade levels of methionine hydroxy analogue

Lipid peroxidation, protein oxidation and antioxidant status of serum and muscle in juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of methionine hydroxy analogue (MHA: 0, 5.1, 7.6, 10.2, 12.7, 15.3 g kg^?1 diet) for 60 days were investigated. Both malondialdehyde and protein carbonyl content in serum and muscle decreased with increasing dietary MHA level up to 5.1–10.2 g kg^?1 diet (P < 0.05). Anti‐hydroxyl radical and activities of catalase, glutathione peroxidase and glutathione reductase in muscle and serum, as well as anti‐superoxide anion, superoxide dismutase activity and glutathione content in serum, increased with optimal MHA supplement (P < 0.05). Meanwhile, glutathione‐S‐transferase activity in serum showed a downward trend with dietary MHA up to 7.6 g kg^?1 diet (P < 0.05). These results indicated that MHA improved antioxidant status and depressed lipid and protein oxidation in serum and muscle.     

Effect of dietary protein reduction with lysine and methionnine supplementation on growth performance,body composition and total ammonia nitrogen excretion of juvenile grass carp,Ctenopharyngodon idella

A 63‐day growth trial was undertaken to estimate the effects of supplemented lysine and methionine with different dietary protein levels on growth performance and feed utilization in Grass Carp (Ctenopharyngodon idella). Six plant‐based practical diets were prepared, and 32CP, 30CP and 28CP diets were formulated to contain 320 g kg^?1, 300 g kg^?1 and 280 g kg^?1 crude protein without lysine and methionine supplementation. In the supplementary group, lysine and methionine were added to formulate 32AA, 30AA and 28AA diets with 320 g kg^?1, 300 g kg^?1 and 280 g kg^?1 dietary crude protein, respectively, according to the whole body amino acid composition of Grass Carp. In the groups without lysine and methionine supplementation, weight gain (WG, %) and specific growth rate (SGR, % day^?1) of the fish fed 32CP diet were significantly higher than that of fish fed 30CP and 28CP diets, but no significant differences were found between 30CP‐ and 28CP‐diet treatments. WG and SGR of the fish fed 32AA and 30AA diets were significantly higher than that of fish fed 28AA diets, and the performance of grass carp was also significantly improved when fed diets with lysine and methionine supplementation (P < 0.05), and the interaction between dietary protein level and amino acid supplementation was noted between WG and SGR (P < 0.05). Feed intake (FI) was significantly increased with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05), but feed conversion ratio (FCR) showed a significant decreasing trend (P < 0.05). Two days after total ammonia nitrogen (TAN) concentration test, the values of TAN discharged by the fish 8 h after feeding were 207.1, 187.5, 170.6, 157.3, 141.3 and 128.9 mg kg^?1 body weight for fish fed 32CP, 32AA, 30CP, 30AA, 28CP and 28AA diets, respectively. TAN excretion by grass carp was reduced in plant‐based practical diets with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05). The results indicated that lysine and methionine supplementation to the plant protein sources‐based practical diets can improve growth performance and feed utilization of grass carp, and the dietary crude protein can be reduced from 320 g kg^?1 to 300 g kg^?1 through balancing amino acids profile. The positive effect was not observed at 280 g kg^?1 crude protein level.     

日粮锌源和锌水平对断奶仔猪血清及组织铜、铁、锌沉积的影响

选用临床检查健康的(26±2)日龄"杜×长×大"三元杂交断奶仔猪100头,按体质量和性别随机分为5组,每组20头,分别饲喂基础日粮、基础日粮+2000mg/kg氧化锌、基础日粮+3000mg/kg氧化锌、基础日粮+250mg/kg蛋氨酸锌、基础日粮+500mg/kg蛋氨酸锌。试验期14d。于断奶后0,7,14d,经前腔静脉采血,用原子吸收光谱仪检测血清中铜、铁、锌水平。试验结束时,每组选5头仔猪放血致死,取心、肝、肾、脑、脾、胸腺组织,测定铜、铁、锌含量。结果显示,仔猪断奶后,血清中铜、锌水平显著或极显著下降(P0.05或P0.01);添加不同锌源和锌水平的高锌日粮能提高断奶仔猪肝、肾、脑、血清锌的含量,显著或极显著降低仔猪血清铜和心、胸腺铜以及脾铁水平(P0.05或P0.01),对血清铁及其他组织铁含量无明显影响。这表明高锌日粮能增加断奶应激仔猪体内锌水平,降低部分组织中铜、铁含量。     

补充母源性有机硒与蛋氨酸对后代仔鸡腿肉过热味的影响

通过测定后代仔鸡腿肉冷藏期间过热味发生的氧化产物含量变化,探讨母源性有机硒和蛋氨酸补充对后代仔鸡腿肉过热味产生的影响。选用450只52周龄狼山种母鸡随机分成9个处理组,每组5个重复,每个重复10只鸡,分别在玉米-豆粕型基础日粮中添加不同水平的有机硒和蛋氨酸。各处理组有机硒(0.1%)的水平为0.13,0.43和0.73mg/kg,DL-蛋氨酸(99%)的水平为0.32,0.40和0.54mg/kg。饲喂后收集种蛋孵化。每处理组挑选160只健康雏鸡,随机分成5个重复,饲喂相同日粮。13周龄时,从每个重复随机挑选2只仔母鸡,屠宰,取样,测定指示过热味发生的氧化产物含量的变化。研究发现:在过热味发展初期(6h)母源性有机硒和蛋氨酸对总醛、己醛、1-戊醇、2,3-辛二酮和2-戊基-呋喃的含量影响显著,存在互作效应(P0.05);对过热味发展后期(3d)挥发性氧化产物的含量影响不显著。高硒高蛋氨酸组与低硒低蛋氨酸组总醛、己醛和1-戊醇的含量最低,而2,3-辛二酮与2-戊基呋喃的含量最高;两组间各物质含量差异不显著。冷藏时间对各种挥发性氧化产物的含量均有极显著影响(P0.01)。因此,在种母鸡日粮中添加硒和蛋氨酸可防止13周龄仔鸡腿肉过热味的产生。     

Supplementation of diets for lactating sows with zinc amino acid complex and gastric nutriment‐intubation of suckling pigs with zinc methionine on mineral status,intestinal morphology and bacterial translocation in lipopolysaccharide‐challenged weaned pigs

Sixty‐four pigs from 16 sows were used to evaluate addition of zinc amino acid complex (ZnAA) to lactating sows and gastric nutriment‐intubation of zinc methionine (ZnMet) to suckling pigs on mineral status, intestinal morphology and bacterial translocation after weaning. Sows were fed a barley‐based diet supplying 120 ppm zinc (Zn; control) or the control diet supplemented with 240 ppm Zn from ZnAA. At birth, day‐10 and day‐21 (weaning) of age, pigs from each litter were nutriment‐intubated with 5 ml of an electrolyte solution without or with 40 mg Zn from ZnMet. At weaning, 24 h prior to the collection of small and large intestinal lymph nodes and sections of the duodenum, jejunum and ileum, the pigs received an intramuscular injection of saline without or with 150 μg/kg body weight of Escherichia coli O26:B6 lipopolysaccharide (LPS). With the exception of a tendency (p = 0.09) for lower serum concentration of copper in pigs at weaning from ZnAA‐supplemented sows, there were no differences (p > 0.1) than for pigs from control‐fed sows for mineral status or intestinal morphology. Nutriment‐intubation of ZnMet increased serum (p = 0.001) and liver (p = 0.003) Zn concentrations, number of goblet cells per 250 μm length of jejunal villous epithelium (p = 0.001) and tended (p = 0.06) to enhance jejunum mucosa thickness. Interactive effects (p < 0.05) for higher jejunal villi height and villi:crypt ratio and increased ileal goblet cell counts were apparent for pigs from ZnAA‐supplemented sows that also received nutriment‐intubation of ZnMet. Challenge with LPS increased (p = 0.05) ileal villous width. Nutriment‐intubation of ZnMet decreased (p = 0.05) anaerobic bacteria colony forming unit counts in the large intestinal mesenteric lymph nodes. In conclusion, nutriment‐intubation of ZnMet increased serum and liver tissue concentrations of Zn and resulted in limited improvement to intestinal morphology of weaned pigs.     

ORIGINAL ARTICLE: The effect of dietary methionine levels on endogenous nitrogen and endogenous amino acids flows in growing goats

The effect of dietary methionine (Met) levels on endogenous N and amino acids (AA) flows at different part of the digestive tract of growing goats was determined using a ¹⁵N isotope dilution technique. Three goats (25 ± 2.5 kg) were fitted with the ruminal, duodenal and ileal cannulae and allocated to three dietary treatments in a 3 × 3 Latin square design. The dietary treatments consisted of a total mixed ration containing three levels of Met (0.15%, 0.25% and 0.35%) respectively. It was found that at 0.15% Met level, the lowest flow in endogenous N and total AA at the duodenum and ileum occurred. The endogenous N secretion contributed to 26% and 23% of the duodenal and ileal total N flows, respectively, and the proportions were not affected by the dietary Met levels. The duodenal and ileal flows of endogenous total AA were 11.1, 11.8, 11.3 g/d and 2.9, 3.9, 4.1 g/d respectively. The average real digestibility of N was 65%, 87% and 95% in the forestomach, intestine and whole digestive tract respectively.     

Effect of rumen‐protected choline and methionine on physiological and metabolic disorders and reproductive indices of dairy cows

The objective of this study was to investigate the effect of feeding different levels of ruminally protected methionine and choline on the incidence of physiological and metabolic disorders, production, and some of the reproductive indices of Holstein dairy cows. Forty Holstein dairy cows in their first and second lactation were used from 4‐week pre‐partum through 20‐week post‐partum and randomly assigned to receive one of the following treatments: 18 g/day of rumen‐protected methionine (RPM), 60 g/day of rumen‐protected choline (RPC), 18 g/day of RPM + 60 g/day of RPC, and neither supplement (control). The treatments significantly affected services per conception and open days of lactating dairy cows (p < 0.05), but did not affect significantly on days to first oestrus and number of pregnant cows. RPM + RPC‐fed cows had the lowest open days, days to first oestrus and services per conception compared with other groups. The effect of treatments was significant on the incidence of metabolic and physiological problems except for foot/leg problems. Cows fed RPM+RPC had the lowest health problems compared with other groups (p < 0.05). Results indicate that the supplementation of RPM and RPC can improve reproductive performance and health status of dairy cows.     

Effect of dietary methionine on growth performance and insulin‐like growth factor‐I mRNA expression of growing meat rabbits

An experiment was conducted to determine the effects of different amounts of dietary methionine on growth performance, serum protein, growth hormone (GH), insulin‐like growth factor‐I (IGF‐I) concentrations and IGF‐I mRNA expression of growing meat rabbits. One hundred weaned growing meat rabbits were allocated to individual cages and randomly divided into five groups. The methionine addition concentrations of the five groups were 0, 2, 4, 6 and 8 g/kg diet (as‐fed basis) and sulphur amino acids (SAA) concentrations ranging from 3.8 to 11.6 g/kg diet, respectively. The results obtained were as follows: the average daily gain of 2, 4 and 6 g/kg diet groups was higher than that of 0 g/kg diet group (p < 0.01). The feed gain ratio of the 4 g/kg diet group was lower than those of 0 and 8 g/kg diet group (p < 0.01). Methionine concentrations did not affect serum urea nitrogen, total protein, insulin and IGF‐I concentration (p > 0.05). The quadratic effects of methionine on the serum concentration of albumin (Alb) and GH were obtained (p = 0.013, p = 0.018). The quadratic effect of methionine amount on IGF‐I mRNA expression was obtained (p = 0.045). The serum concentration of Alb of the 4 g/kg diet group was higher than those of 0 and 8 g/kg diet group (p < 0.01). The serum concentration of GH of 8 g/kg diet group was higher than that of the 0 g/kg diet group (p < 0.05). The liver IGF‐I mRNA expression of 4 g/kg diet group was higher than those of the 0 and 8 g/kg diet group (p < 0.05). Providing a diet mainly consisted of corn, wheat bran and peanut vine, the optimum dietary methionine addition concentration and SAA concentration for a weaner to 2‐month‐old growing meat rabbits were shown to be 2 and 5.7 g/kg diet respectively.