Effects of protein concentration on responses to dietary lysine by chicks

Chicks were fed on diets varying in crude protein (CP) content (140 to 280 g/kg diet) in either 8 steps, experiment 1, or 6 steps, experiment 2. Protein composition was held constant in each experiment. At each protein concentration, 5 (experiment 1) or 6 (experiment 2) concentrations of lysine were tested, ranging from 40 to 60 g/kg CP. Growth rate and efficiency of food utilisation to 21 d of age responded to increasing dietary protein contents up to about 230 g CP/kg. An estimate of lysine requirement at each protein concentration was obtained by fitting a quadratic curve to the response data and calculating the dose of lysine (g/kg CP) needed to maximise either growth rate or gain/food ratio. Although no growth response to dietary protein was obtained between 240 and 280 g CP/kg, the amount of lysine needed to maximise growth and gain/food ratio over this range increased systematically when expressed as g/kg diet, but remained constant if expressed as g/kg CP. The regression of lysine required (g/kg diet) for maximum performance (growth or food efficiency) on CP (g/kg diet) was strictly linear for both responses in both experiments throughout the entire range studied (140 g CP/kg to 280 g CP/kg). The estimated lysine requirement was 0.053 of the CP in experiment 1 and 0.055 of the CP in experiment 2. It is concluded that a fixed ratio of lysine to protein should be specified in practical diet formulation, rather than a minimum dietary concentration of lysine. This would ensure that, if the dietary protein content rises above a prescribed minimum value in least-cost formulation, an appropriate adjustment will automatically be made to the lysine content of the solution.     

Note on the effects of protein concentration on responses to dietary lysine by chicks

1. This paper gives further analyses of data from previously reported trials in which chicks were fed diets with protein concentrations ranging from 140 to 280 g/kg diet, with the lysine content varied at each protein concentration. 2. Alternative methods of estimating the lysine requirement, at each concentration of protein, are investigated. 3. Although these methods produce rather different estimates of requirement, they do not change the conclusion that the lysine needed for maximum growth or maximum efficiency of food utilisation is a linear function of dietary protein concentration throughout the range from 140 to 280 g crude protein/kg. 4. It is concluded that lysine requirements for growing chicks should be specified as a proportion of the protein and not as a proportion of the diet.     

泌乳母猪赖氨酸营养需要的研究进展

泌乳母猪饲养是养猪生产的重要环节之一。由于现代母猪饲养管理方式和品种选育造成的基因型改变等导致其营养需要量也发生变化。赖氨酸作为泌乳母猪最重要的氨基酸一直得到营养学家的关注。本文综述了近20年来泌乳母猪赖氨酸的研究进展和实际条件下运用模型确定的赖氨酸需要量,以期为实际生产服务。     

Effects of arginine and protein on chicks' responses to dietary lysine

1. A chick experiment was designed to test whether the proven effect of excess protein on the requirement for lysine was associated with the arginine content of the protein. 2. Protein contents of 180, 220, 260 and 300 g/kg diet were fed in combination with lysine concentrations of 38, 43, 48, 53 and 58 g/kg crude protein and arginine concentrations of 49.4 or 68.4 g/kg crude protein. 3. Growth rate and efficiency of food utilisation were not significantly affected by the arginine content of the protein. Significant responses to lysine were obtained at all protein contents. 4. Lysine required for maximum growth or maximum food efficiency increased in direct proportion to the protein content of the diet and was not affected by arginine content of the diet within the range of concentrations tested.     

日粮蛋白、能量水平对哺乳母猪繁殖性能的影响

试验选用14头分娩日期相近的杜长大经产母猪,按体重、胎次随机分成2个处理,每个处理7个重复,1头1个重复。在28d的试验期母猪自由采食和饮水。研究饲喂按NRC(1998)配制的高蛋白、高能量水平日粮(蛋白为18.50%和代谢能为14.23MJ/kg)与按NRC(1988)配制的日粮(蛋白为17.10%和代谢能为13.19MJ/kg)对母猪生产性能的影响。分娩当天、28d测定母猪背膘厚度、体重、采食量;分娩当天、21d、28d测定仔猪窝重;21d采取母猪乳样,分析乳固形物、乳蛋白、乳脂成分。结果表明:高水平日粮对母猪采食量和失重有显著影响(P<0.05),对仔猪平均日增重和母猪乳成分没有显著影响(P>0.05)。     

Protein (lysine) restriction in primiparous lactating sows: effects on metabolic state,somatotropic axis,and reproductive performance after weaning

Low protein intake during lactation has been demonstrated to increase the loss of body protein and to reduce the reproductive performance of female pigs. The objectives of the current experiment were 1) to determine whether protein (lysine) restriction alters levels of somatotropic hormones, insulin, follicle-stimulating hormone, and leptin around weaning, and 2) to evaluate the relationships between these eventual alterations and postweaning reproductive performance. One day after farrowing, crossbred primiparous sows were randomly allocated to one of two diets containing 20% crude protein and 1.08% lysine (C, n = 12) or 10% crude protein and 0.50% lysine (L, n = 14) during a 28-d lactation. Diets provided similar amounts of metabolizable energy (3.1 Mcal/kg). Feed allowance was restricted to 4.2 kg/d throughout lactation, and litter size was standardized to 10 per sow within 5 d after farrowing. Catheters were fitted in the jugular vein of 21 sows around d 22 of lactation. Serial blood samples were collected 1 d before (day W - 1) and 1 d after (day W + 1) weaning, and single blood samples were collected daily from weaning until d 6 postweaning (day W + 6). Sows were monitored for estrus and inseminated. They were slaughtered at d 30 of gestation. During lactation, litter weight gain was similar among treatment groups. Reduced protein intake increased (P < 0.001) sow weight loss (-30 vs -19 kg) and estimated protein mobilization throughout lactation (-4.1 vs -2.0 kg). On day W - 1, L sows had higher (P < 0.02) plasma glutamine and alanine concentrations, but lower (P < 0.05) plasma tryptophan and urea than C sows. Mean and basal plasma GH were higher (P < 0.001), whereas plasma IGF-I and mean insulin were lower in L than in C sows on day W - 1. Preprandial leptin did not differ between treatments on day W - 1, but was higher (P < 0.01) in L sows than in C sows on day W + 1. Mean FSH concentrations were similar in both treatments on day W - 1 (1.3 ng/mL), but L sows had greater (P < 0.001) mean FSH on day W + 1 than C sows (1.6 vs 1.2 ng/mL). The weaning-to-estrus interval (5 +/- 1 d) was similar in both groups. Ovulation rate was lower in L than in C sows (20.0 +/- 1 vs 23.4 +/- 1, P < 0.05). No obvious relationships between reproductive traits and metabolic hormone data were observed. In conclusion, these results provide evidence that protein (lysine) restriction throughout lactation alters circulating concentrations of somatotropic hormones and insulin at the end of lactation and has a negative impact on postweaning ovulation rate.     

Different dietary methionine to lysine ratios in the lactation diet:effects on the performance of sows and their offspring and methionine metabolism in lactating sows

Background: Over the last decade, the nutritional requirements of lactating modern genotype sows have increased. The current nutritional recommendations might be unable to meet the needs of increased litter size and milk production, and thus the nutritional requirements need to be re-evaluated. The current study was conducted to investigate the effects of dietary methionine to lysine(Met:Lys) ratios on the performance of and methionine metabolism in lactating sows.Results: During the 1~(st) week of lactation, piglets reared on sows in the 0.37 to 0.57 Met:Lys ratio groups grew faster than those reared on sows in the control group(0.27)(P 0.01). The 0.37-ratio group showed increased levels of GSHPx in plasma during lactation(P 0.01) and decreased concentrations of urea nitrogen in the plasma of sows(P 0.05).Compared with the 0.27-ratio group, the levels of T-AOC and GSH-Px in the plasma and homocysteine in the milk of lactating sows were significantly increased in sows in the 0.47-ratio group(P 0.01). In sows fed a 0.57-ratio diet, the levels of glutathione and taurine in the plasma and milk were improved significantly during lactation. However, the content of TBARS in the blood(P 0.05 at day 7 and P = 0.06 at weaning day) was increased(P 0.01). Moreover, there were linear increases in the levels of homocysteine in the blood and milk of sows during the lactation period(P 0.01)with increased dietary Met:Lys ratios in the lactation diet.Conclusions: The current study indicated that increasing the dietary Met:Lys ratio(0.37～0.57) in the lactation diet had no significant effect on the overall performance of sows or the colostrum and milk composition, but it increased piglet mean BW and piglet ADG during the first week of lactation. Increasing dietary methionine levels had no significant effect on antioxidant function in lactation sows, even though it increased levels of GSH and GSH-Px in the plasma of sows during lactation. However, the content of homocysteine in the plasma and milk increased during lactation due to a high level of dietary methionine.     

Effects of exposure to high ambient temperature and dietary protein level on performance of multiparous lactating sows

Fifty-nine multiparous Large White x Landrace sows were used to determine the effects of high ambient temperature and level of dietary heat increment on lactation and reproductive performance. During a 28-d lactation and the 14-d postweaning period, ambient temperature was maintained constant at 20 or 29 degrees C. Experimental diets fed during lactation were a control diet (NP; 17.6% crude protein) and two low-protein diets obtained by reduction of CP level (LP; 14.2% CP) and both reduction of CP and addition of 4% fat (LPF; 15.2% CP); the NE:ME ratio was 74.3, 75.6, and 75.8% for NP, LP, and LPF diets, respectively. All diets provided 0.82 g of digestible lysine/MJ of NE, and ratios between essential amino acids and lysine were above recommendations. During the ad libitum period (i.e., between d 7 and 27 of lactation), ADFI and NE intake decreased, respectively, from 7.63 to 4.22 kg and 82.0 to 43.3 MJ of NE when the temperature increased from 20 to 29 degrees C. Exposure to 29 degrees C reduced litter BW gain (2,152 vs 2,914 g/d) and increased lactation BW loss (34 vs 16 kg) but increased postweaning BW gain (2 vs - 4 kg). Expressed per kilogram of feed intake, water intake increased from 4.0 to 7.5 L between 20 and 29 degrees C. Compared with the NP diet, low-CP diets (LP or LPF) maintained performance and reduced total N excretion (-22.5%) in lactating sows at thermoneutrality and attenuated the negative effects of high temperature on NE intake and BW loss (40.9 vs 47.9 MJ of NE/d and 41 vs 30 kg for NP and LP + LPF diets, respectively). Temperature and diet composition did not affect the reproductive performances, and the mean weaning-to-estrus interval was 4.9 d. The respiratory rate and skin, udder, and rectal temperatures increased markedly at 29 degrees C (105 vs 33 breaths per min and 37.8 vs 36.1 degrees C, 38.9 vs 38.2 degrees C, and 39.5 vs 38.8 degrees C, respectively) without any effect of diet. In conclusion, low heat increment diets (i.e., with reduced CP/NE ratio) did not affect lactation performance of sows at thermoneutrality and attenuated the effects of high ambient temperature on energy intake and BW loss. At any ambient temperature, N excretion can be markedly reduced.     

Performance of lactating sows in response to the dietary valine supply

In order to determine the requirement of lactating sows for valine (Val) the effects of graded Val supplementations on feed intake, milk yield and changes of body weight of sows and piglets were examined using 54 multiparous sows over a total of 72 lactations (35 days). The sows were randomly assigned to six treatments (1-6). Each group received the same basic diet, covering the requirements of energy and nutrients except Val (4.5 g native Val, i.e. 3.5 g apparent ileal digestible Val). Adding crystalline l-Val dietary Val concentrations of 5.5, 6.5, 8.5, 10.5 and 14.5 g/kg, respectively, were realized. Feed intake of the sows was determined daily, body weight was determined on day 110 of gestation and day 1, 22 and 35 of lactation. The piglets were weighed on day 1, 21 and 35. The intake of piglet feed, which was offered from day 21, was determined at day 35 for each litter. Milk yield was determined using the weigh-suckle-weigh-method at day 13, 14, 20 and 21, fat and protein contents were analysed in hand-milked samples with infrared spectroscopy. Feed intake (kg/day) of the sows during lactation averaged 2.9, 4.3, 4.6, 4.6, 4.9 and 5.1 for treatments 1-6, respectively. For treatments 1 and 2 body weight losses of the sows during lactation were higher (1207 and 805 g/day, respectively) and milk production was lower (7076 and 8686 g/day, respectively), compared with the average of treatments 3-6 (625 g/day body weight loss; 9263 g milk/day). Daily weight gain of the piglets was also lower (146 and 171 g/day vs. 200 g/day) leading to lower weaning weights of 6.6 and 7.5 vs. 8.5 kg. As a consistent growth depression of the piglets in Val deficiency must be assumed, at least 6.5 g Val corresponding to 5.5 g apparent ileal digestible Val per kg lactation feed must be recommended.     

日粮赖氨酸与粗蛋白质比例对妊娠母猪繁殖性能的影响

妊娠母猪的蛋白质和氨基酸需要量包括母体维持需要和妊娠期间沉积需要两个部分。现代母猪由于基因型的改进 ,体内沉积和仔猪初生重有增加的潜力 ,Manhan ( 1 998)研究证明 ,增加妊娠期间赖氨酸和蛋白质摄入量提高了仔猪初生重和仔猪断奶窝重。因此 ,充足的赖氨酸和蛋白质供应使     

Effects of protein concentration on responses to dietary tryptophan by chicks

1. Chicks were fed from 4 to 18 d on 40 diets containing all combinations of 8 crude protein (CP) concentrations (from 160 to 300 g/kg) and 5 tryptophan concentrations (from 7.5 to 13.5 g tryptophan/kg CP). 2. At each protein concentration there were responses in growth rate and in efficiency of food utilisation to supplementation with tryptophan. Curves were fitted to estimate the maximum response at each protein concentration. 3. The amounts of tryptophan required (g/kg) for maximum growth and maximum food efficiency were each linear functions of dietary protein concentration. The chick's requirement for tryptophan can be expressed as 12 g/kg CP. 4. It is concluded that a fixed ratio of tryptophan to protein should be specified in practical diet formulation, rather than a minimum dietary concentration of tryptophan.     

日粮蛋白质与赖氨酸水平对断奶仔猪益生素添加效果的影响

为探讨不同日粮养分浓度对益生素添加效果的影响 ,将 4 8头 2 8日龄断奶仔猪随机均分 4组 ,以常规日粮为对照组 ,经 2 8d试验 ,结果发现 :益生素 (0 .1% )在常规日粮中添加 ,能提高断奶仔猪 9.0 3%的增重速度 (P<0 .0 5 )和 6 .3%的饲料转化率 ;而在低蛋白质日粮 (低赖氨酸水平和理想赖氨酸水平 )中的添加 ,能比对照组分别提高 16 .4 3%和 17.97%的增重速度(P<0 .0 1) ,以及 11.2 %和 11.7%的饲料转化率 ,腹泻率也比对照组有明显降低。     

Effects of dietary lysine intake during lactation on blood metabolites, hormones, and reproductive performance in primiparous sows

Effects of three dietary lysine (protein) concentrations during lactation on metabolic state, protein metabolism, reproductive hormones, and performance were investigated in 36 primiparous sows. Sows were assigned randomly to one of three diets containing .4% (low lysine, LL), 1.0% (medium lysine, ML), or 1.6% (high lysine, HL) total lysine from intact protein sources. All diets contained 2.1 Mcal NE/kg and exceeded the recommended requirements for all other nutrients. Actual lysine intakes over an 18-d lactation were 16, 36, and 56 g/d for sows fed LL, ML, and HL, respectively. Fractional breakdown rate of muscle was determined on d 4 and 15 of lactation by using a three-compartment kinetic model of 3-methylhistidine metabolism. Increasing lysine intake during lactation did not affect fractional breakdown rate of muscle on d 4 of lactation but decreased it on d 15 (P < .05). Sows fed LL had a reduced number of LH pulses on d 12 and 18 (P < .05) and reduced serum estradiol (E2) concentration on d 18 of lactation compared with sows fed ML and HL treatments. However, LH pulses and E2 concentrations were similar between ML and HL treatments (P > .35). Increasing lysine intake increased serum urea nitrogen (SUN) and postprandial insulin concentrations (P < .05) during lactation but had no effect on plasma glucose concentrations (P > .20). Sows fed HL had greater serum IGF-I on d 6 and 18 than sows fed ML (P < .05). Number of LH peaks was correlated with serum insulin concentration 25 min after feeding on d 6 and 18 (r = .31 to .41; P < .1) and pre- (r = .33 to .46) and postprandial (r = .30 to .58) SUN concentrations (P < .05) during different stages of lactation. Results indicate that, compared with medium lysine intake, low lysine intake increased muscle protein degradation and decreased concentrations of insulin, SUN, and estradiol and LH pulsatility. In contrast, high lysine (protein) intake increased SUN, insulin, and IGF-I, but did not increase secretion of estradiol and LH compared with medium lysine intake. Furthermore, nutritional impacts on reproduction may be mediated in part through associated effects on circulating insulin concentration.     

日粮蛋氨酸、赖氨酸水平对皖西白鹅种鹅繁殖力的影响

将蛋氨酸水平 ( 0 2 1%、0 3 6%、0 5 1% )与赖氨酸水平 ( 0 49%、0 64 %、0 79% )组成 9个组合 ,探讨其对皖西白鹅种鹅繁殖力的影响。结果发现 :①蛋氨酸影响着除受精率以外的所有繁殖力指标 (P <0 0 1) ;②赖氨酸只影响产蛋量 (P <0 0 5 ) ;③ 0 3 6%的蛋氨酸与 0 64 %的赖氨酸组合 ,能最佳发挥皖西白鹅种鹅的繁殖性能。     

ORIGINAL ARTICLE: Effects of dietary glucose inclusion on reproductive performance,milk compositions and blood profiles in lactating sows

Twenty‐four multiparous sows were used to investigate the effects of dietary glucose inclusion on reproductive performance, milk compositions, blood metabolites and hormones during lactation. The sows were randomly assigned to four treatments and each treatment had six replicates (sows). The diets were added with 0%, 1%, 3% or 5% glucose at the expense of corn and fed to sows for 24 days. The loss of backfat thickness during lactation was quadratically decreased (p = 0.008) and the wean‐to‐oestrus interval was shortened (linear, p = 0.013; quadratic, p = 0.009) with increasing levels of dietary glucose supplementation. The reproductive performance was not affected (p > 0.05) by different dietary glucose contents. Increased concentrations of total solid and fat in milk were noted (p < 0.05), whereas there was no difference on colostrum compositions. With increasing levels of dietary glucose inclusion, the concentrations of blood urea nitrogen (p = 0.004) and glucose (p = 0.029) were linearly increased at weaning. The concentrations of insulin were increased at post‐farrowing (linear, p = 0.027; quadratic p = 0.013) and weaning (linear, p = 0.029; quadratic, p = 0.017), respectively. Furthermore, the pulses of insulin and FSH at weaning were linearly (p = 0.049) and quadratically (p = 0.015) increased with the increasing levels of dietary glucose inclusion. In conclusion, this study indicated that inclusion of 3% glucose in lactating diet could reduce backfat loss, increase milk fat and have no negative effect on reproductive performance in multiparous sows.     

Study of broiler chicken responses to dietary protein and lysine using neural network and response surface models

1. In this study, neural network (NN) and response surface (RS) models were developed to investigate the response [average daily gain (ADG) and feed efficiency (FE)] of young broiler chickens to dietary protein and lysine. For this purpose, data on their responses to dietary protein and lysine were extracted from the literature and separate NN and RS models were constructed.

2. Comparison between the NN and RS models revealed higher accuracy of prediction with the NN models compared to the RS models. In terms of R ² values, the NN models developed for both ADG (R ² = 0.923) and FE (R ² = 0.904) were far superior to the RS models (R ² for ADG = 0.511; R ² for FE = 0.67). This suggests that the NN models can serve as an alternative option to conventional regression approaches including use of RS models.

3. Optimisation of the NN models developed for response to protein and lysine showed that diets containing 220.7 (g/kg of diet) protein and 12.85 (g/kg of diet) lysine maximise ADG, whereas maximum FE is achieved with diets containing 241.3 and 13.12 (g/kg) protein and lysine, respectively. Based on the optimisation results, optimal dietary protein and lysine concentrations for maximum FE in broiler chickens during the starting period are higher than for ADG.     

日粮纤维对母猪繁殖性能的影响

通常 ,为保证最佳的经济性状和健康水平 ,对繁殖母猪要限制饲养以保持其体况在整个繁殖周期中相对恒定 (Dourmad等 ,1 994、1 996)。而限饲所提供的饲料水平仅占随意采食量的 0 40～ 0 60(Pettigrew和Blackshaw ,1 989;Brouns等 ,1 995 ) ,显然不能满足其采食需要 ,从而导致群饲时的攻击性和争食现象 (Appleby和Lawrence ,1 987;Terlouw等 ,1 991 ;Edwards,1 992 ;Terlouw和Lawrence ,1 993;Spooler,1 995 )。妊娠期限饲会降低仔猪初生重和成活率 ,母猪分娩和断奶时体脂沉积过少还会延迟断奶后的发情 ,并降低受孕率 ,导致母猪繁殖性…     

Response of pregnant and lactating sows to reduced protein content in complete compound feed

The experimental material consisted of 42 sows divided into 3 feeding groups, each containing 14 sows fed complete compound feed varying in protein content. Protein and amino acid content of the feed fed to the control group was in compliance with Polish standards. Protein content in the experimental groups was reduced by 10% and 20%, respectively. At the same time, lysine, methionine, threonine and tryptophane content was supplemented to the level of the control group. All pregnant and lactating sows were fed individually. The condition of the sows was determined by measuring the thickness of backfat at the P2 position on days 30 and 105 of pregnancy and on day 25 of lactation. The data analyzed in the study included: the total number of piglets born, their body weight gain, milk composition, weaning-to-estrus interval and the farrowing rate. Protein content of the compound feed did not have a significant impact on the increment in backfat during pregnancy and losses during lactation. The sows fed compound feed with reduced protein content gave birth to 0.7 and 0.6 less piglets per litter than the control animals. However, due to lower losses, they bred 0.3 and 0.4 more piglets than the control sows. Average body weight of a piglet on day 21 was 0.5 kg lower in the experimental than in the control group. Dry matter, protein, fat and lactose content of the sow's milk did not depend on protein content of the feed. The weaning-to-estrus interval in the experimental groups was one day longer than in the control group. The reproductive rate accounted for 86% and was comparable in all the groups.