Effects of dietary lysine levels and lighting conditions on intramuscular fat accumulation in growing pigs

This study was conducted to test our hypothesis that intramuscular fat (IMF) accumulation increases in pigs fed on a low lysine diet during the dark period than those fed on the same diet during the light period. Using barrows aged 6 weeks, we monitored whether serum glucose and insulin levels were affected by light conditions. Two diets with different levels of lysine, 0.78% (LL diet) and 1.37% (control diet) were prepared. Eight pigs were fed on the diet during the light period, while the remaining pigs were fed during the dark period. The pigs were fed either the LL diet or the control diet. Although IMF contents of Longissimus dorsi (LD) muscle were higher in the pigs fed on a LL diet (p < .05), the light conditions had no effect. Low dietary lysine caused reduction in serum glucose levels (p < .05) and serum insulin levels (p = .0613). However, they were also unaffected by the lighting conditions. To gain further insights, we determined the messenger RNA levels of insulin receptor, insulin receptor substrate 1, acetyl CoA carboxylase, and fatty acid synthase in LD and Rhomboideus muscles and in the liver.     

Promotion of intramuscular fat accumulation in porcine muscle by nutritional regulation

Recently, pork with marbling has received attention as good quality pork and scientists are required to develop methods to produce pork with reasonable amounts of intramuscular fat (IMF). The aim of this review is to describe studies relevant to promotion of IMF accumulation in porcine muscle by nutritional regulation. The main focus is on effect of dietary lysine levels. First, we found dietary low lysine up‐regulated glucose transporter protein 4 messenger (m)RNA expression in Longissimus dorsi (L. dorsi) and Rhomboideus muscles. In addition, the proportion of oxidative fiber of both muscles was also enhanced by dietary low lysine. Because it has been observed that higher oxidative capacity is associated with higher IMF content, we hypothesized that dietary low lysine would promote IMF accumulation. Further, higher mRNA abundance of peroxisome proliferator‐activated receptor γ, a master regulator of adipogenesis, in both muscles induced by dietary low lysine, supported this hypothesis. Indeed, IMF content of L. dorsi muscle of finishing pigs given a low lysine diet for 2 months until reaching the market weight was twice that of pigs given a control diet. Possible underlying mechanisms of IMF accumulation in porcine muscle and future perspectives are also discussed in this review.     

Nitrogen balance during compensatory growth when changing the levels of dietary lysine from deficiency to sufficiency in growing pigs

Two experiments were conducted to elucidate the nitrogen (N) balance of pigs exhibiting compensatory growth when changing the dietary lysine levels from deficiency to sufficiency. Experiment 1 elucidated whether pigs exhibited compensatory growth with dietary lysine sufficiency. Twenty 6‐week‐old males were assigned to one of two treatments: control and LC (lysine and control). Control pigs were fed a control diet throughout the 24‐day experimental period, whereas LC pigs were fed a low lysine diet until day 21 of the experiment, followed by the control diet until the end of experiment. The dietary lysine sufficiency treatment induced an 80% increase in the growth rate of LC pigs (P < 0.05). Experiment 2 focused on the N balance of pigs that exhibited compensatory growth with dietary lysine sufficiency. Eighteen 6‐week‐old males were assigned to one of three treatments: control, LC, and LL (low lysine). LL pigs were fed a low lysine diet throughout the 24‐day experimental period. Pigs that exhibited compensatory growth with dietary lysine sufficiency tended to retain a higher amount of N than control pigs (P = 0.10). These finding suggest that the compensatory growth induced in pigs by dietary lysine sufficiency was partly attributable to a higher level of N retention.     

Reduced dietary lysine enhances proportion of oxidative fibers in porcine skeletal muscle

The present study was conducted to elucidate the effects of dietary lysine levels on the proportion of oxidative muscle fibers in porcine muscle. Two 6-week-old barrows from each of five litters were used. Each littermate was assigned to one of two diets, control (lysine content: 1.16%) or low lysine (LL) diet (lysine content: 0.73%). The diets were iso-energetic and iso-protein, and contained all essential amino acids (apart from lysine) in the recommended amounts. The pigs were fed these diets for 3 weeks. Citrate synthase (EC 4.1.3.4) activity in longissimus dorsi and rhomboideus muscles was higher in the LL group ( P  < 0.05). In both muscles, pigs fed the LL diet had a higher proportion of muscle fiber with activities of reduced nicotinic amide adenine dinucleotide dehydrogenase (EC 1.6.5.3, P  < 0.01). The abundance of mRNA of peroxisome proliferator-activated receptor γ coactivator 1α in rhomboideus muscle was higher in the LL group ( P  < 0.05), and those of peroxisome proliferator-activated receptor γ2 were higher in both longissimus dorsi and rhomboideus muscles in the LL group ( P  < 0.05). We conclude that reduced intake of dietary lysine enhances proportion of oxidative muscle fiber, and hence oxidative capacity of porcine muscle.     

Effect of lairage time,behaviour and gender on stress and meat quality parameters in pigs

The objective of this study was to determine the effects of lairage time (short vs. long), behavior (aggressive vs. non‐aggressive) and gender (gilts, barrows and boars) on stress and meat quality parameters in pigs (n = 100). In the group with short lairage, aggressive behavior of gilts and boars was observed. At exsanguination, blood samples were collected and levels of blood lactate and plasma cortisol were determined. Post mortem pH value, temperature, drip loss, sensory and instrumental color and meat quality class were determined on the muscle Longissimus dorsi. Higher blood lactate concentration (P < 0.05) and skin blemish score (P <0.001), lower temperature (P < 0.05) and drip loss (P < 0.01), as well as darker, less red and yellow meat color (P < 0.001) were found after long lairage compared to short lairage. Gilts had higher plasma cortisol concentrations than barrows (P < 0.05), while barrows had lower skin blemish scores (P < 0.05) than gilts and boars after long lairage. The highest incidence of PSE (pale, soft and exudative) meat was observed in barrows (100.00%) and boars (91.67%) after short lairage, while the lowest incidence of PSE meat was found in barrows (28.89%) after long lairage. Aggressiveness affected meat temperature, as aggressive pigs had higher meat temperature (P < 0.05) than non‐aggressive pigs.     

Effects of dietary lysine levels on apparent nutrient digestibility and cationic amino acid transporter mRNA abundance in the small intestine of finishing pigs,Sus scrofa

One hundred and twenty pigs were used to evaluate the effects of different dietary lysine levels on the growth performance, apparent nutrient digestibility, and abundance of cationic amino acid transporter messenger RNA (mRNA) in the small intestine of finishing pigs. Pigs received a low lysine diet (LL, 0.60% lysine), moderate lysine diet (ML, 0.80% lysine) or a high lysine diet (HL, 1.00% lysine) for 28 days. A digestion test was carried out during the third week. Although the apparent nutrient digestibility in pigs fed experimental diets were different (P < 0.05) and the highest when pigs were fed ML diet, diets did not change the growth performance. In the duodenum, mRNA abundance of PepT-1, as detected by real-time RT-PCR, was reduced in the LL diet (P < 0.05). A greater abundance of b^0,+AT and PepT-1 mRNA was associated with the ML diet (P < 0.05) in the jejunum and ileum, respectively. In the ileum, the HL diet had a lower abundance of CAT-1 mRNA compared with other diets. These results showed that the finishing pigs would gain better nutrient digestibility when the dietary lysine content was 0.80%, and dietary lysine levels influenced the expression of cationic amino acid transporter mRNA in the small intestine of finishing pigs.     

Candidate gene expression and intramuscular fat content in pigs

Seventy-two pigs of three genetic groups (Brazilian indigenous breed Piau, Commercial line and Crossbred) of both sexes were slaughtered at four live weights (30, 60, 90 and 120 kg). Intramuscular fat (IMF) content in Longissimus dorsi muscle of each animal was extracted and correlated with candidate gene mRNA expression (ATN1, EEF1A2, FABP3, LDLR, MGP, OBSCN, PDHB, TRDN and RYR1). Within slaughter weight of 120 kg, Piau and Crossbred pigs showed higher IMF content (p < 0.05) than commercial animals, with 2.48, 2.08 and 1.00% respectively. Barrows presented higher values of IMF (p < 0.05) than gilts (1.54 and 1.30% respectively). Gene expression of EEF1A2, FABP3, LDLR, OBSCN, PDHB, TRDN and RYR1 were correlated with IMF (p < 0.05) using the whole dataset. For Piau data only, expression of FABP3, LDLR, MGP, OBSCN, PDHB, TRDN and RYR1 showed correlation with IMF (p < 0.05). Genes that have important roles in lipid transportation inside the cell (FABP3) and tissues (LDLR) showed correlation with IMF of, respectively, 0.68 and 0.63 using the whole data set, and 0.90 and 0.91 using data from Piau animals. The highly positive correlation of the LDLR and FAPB3 expression with IMF content may confirm that these genes are important for fat deposition in the porcine L. dorsi muscle.     

The effect of amino acid restriction during the grower phase on compensatory growth, carcass composition and nitrogen utilisation in grower–finisher pigs

Three hundred and ninety six pigs weighing 42 kg (s.d. +/− 2.5 kg), (progeny of Landrace × Large White sows × Meatline boars) (216 boars and 180 females) were assigned to four dietary treatments to determine the effects of restricting dietary lysine during the grower period (approximately 42 to 63 kg) on nitrogen (N) intake, retention and excretion during the finisher period (approximately 63 kg to slaughter at 94 kg). Two experiments, a performance experiment (nine replicates/treatment) and a N balance experiment (four replicates/treatment) were carried out. The experimental treatments were (1) 1.25% lysine from d 0 to d 28 and 1.05% lysine from d 29 to slaughter (HM), (2) 1.05% lysine from d 0 to slaughter (MM), (3) 0.85% lysine from d 0 to d 28 and 1.05% lysine from d 29 to slaughter (LM) and (4) 0.85% lysine from d 0 to slaughter (LL). All diets were pelleted and formulated to contain 13.8 MJ DE/kg. The pigs were group fed in mixed sex pens using single space feeders (11 pigs/feeder, 6 boars and 5 females). In the N balance experiment, sixteen entire male pigs, after 16 days on the diets were placed individually in metabolism crates and urine and faeces were collected. The pigs offered the 0.85% lysine diets during the grower period had a lower average daily gain (ADG) and a poorer feed conversion ratio (FCR) than the pigs offered 1.25% and 1.05% lysine diets (P < 0.05). During the early finisher period (days 29–42) and overall finisher period (days 29–56) pigs on treatment LM had a higher ADG (P < 0.01) and a better FCR (P < 0.05) than pigs on treatment LL. Pigs on treatment LM also had a better FCR than pigs on treatment HM and MM (P < 0.05) during the early finisher period. Pigs on treatment LM had a significantly (P < 0.05) higher lean meat proportion than pigs on treatment LL. During the grower N balance, pigs on the 0.85% lysine diets (treatments LM and LL) had lower N intakes (P < 0.001), N excretions (P < 0.001) and a higher (P < 0.001) nitrogen utilisation than pigs on treatments MM and HM. During the finisher N balance, pigs on treatment LL had a lower N intake (P < 0.001), N excretion (P < 0.01) and N retention (P < 0.05) than pigs on all other treatments. In conclusion, restricting dietary lysine during the grower period reduced growth rate but resulted in a more efficient growth during the early finisher period once dietary lysine was restored.     

Effects of amino acids supplementation in low crude protein diets on growth performance,carcass traits and serum parameters in finishing gilts

This study investigated the effects of amino acids (AA) supplementation in low crude protein (CP) diets on growth performance and carcass characteristics in finishing gilts. One hundred and eighty gilts (59.1 ± 5.1 kg) were randomly allotted to one of five diets which consisted of a high CP (15.6%) diet or four low CP (11.6%) diets for 50 days. The low CP diets were supplemented with lysine + threonine + methionine (LCM), LCM + tryptophan (LCT), LCT + valine (LCV) or LCV + isoleucine (LCI), respectively. Gilts were housed at six pigs per pen with six pens per treatment. At the end of the 50‐day experiment, 30 gilts (one pig per pen) with average body weight (BW) of 98 kg were killed to evaluate carcass traits. The pigs fed the diet supplemented with LCV obtained the highest average daily gain (ADG), which was higher than those of pigs fed the diet supplemented with LCM (P < 0.05). Dietary supplementation with tryptophan, valine and isoleucine in low CP diets increased ADG (linear and quadratic effect, P < 0.05), serum levels of valine (quadratic effect, P < 0.05) and isoleucine (linear and quadratic effect, P < 0.05) and immunoglobulin G (IgG) and IgA (linear and quadratic effect, P < 0.05) in finishing gilts. © 2016 Japanese Society of Animal Science     

Effects of dietary lysine levels on the concentrations of selected nutrient metabolites in blood plasma of late‐stage finishing pigs

Lysine is the first‐limiting amino acid (AA) in typical swine diets and plays very important roles in promoting growth performance of pigs. This research was conducted to study the effects of dietary lysine on blood plasma concentrations of protein, carbohydrate, and lipid metabolites of pigs. Eighteen crossbred finishing pigs (nine barrows and nine gilts; initial BW 92.3 ± 6.9 kg) were individually penned in an environment controlled barn. Pigs were assigned to three dietary treatments according to a randomized complete block design with gender as block and pig as experimental unit (6 pigs/treatment). Three corn and soybean meal‐based diets were formulated to contain total lysine at 0.43%, 0.71%, and 0.98% (as‐fed basis) for Diets I (lysine deficient), II (lysine adequate), and III (lysine excess) respectively. After 4 weeks on trial, jugular vein blood was collected and plasma was separated. The plasma concentrations of total protein, albumin, urea nitrogen (UN), triglyceride, total cholesterol, and glucose were determined using an ACE Clinical Chemistry System (Alfa Wassermann, Inc., West Caldwell, NJ, USA). Data were analysed using the GLM Procedure with PDIFF (adjust = T) option of SAS. No differences (p > 0.10) were found between barrows and gilts for any of the metabolites measured. While there were no differences (p > 0.10) between pigs fed Diets II and III in plasma concentrations of UN, albumin, and total cholesterol, the concentration of albumin in these pigs was higher (p < .05) than that of pigs fed Diet I, and the concentrations of UN and total cholesterol in these pigs were lower (p < .05) than that of pigs fed Diet I. There were no differences (p > 0.10) among the three dietary treatments in plasma concentrations of total protein, triglycerides, and glucose. These findings indicated that the plasma metabolite profile can be affected by changing dietary lysine content only. Thorough understanding how the plasma metabolite profile is alternated by dietary lysine will facilitate nutrient management for more sustainable swine production.     

Tenderization potential of Hanwoo beef muscles from carcasses with differed genders and loin intramuscular fat content levels during post mortem ageing

Carcasses from Hanwoo steers (n = 15) and cows (n = 15) were classified into three groups: group 1 (G1), the carcasses had 10% to < 11.5% intramuscular fat (IMF) in loin muscles; group 2 (G2), the carcasses had 13% to < 14.5% IMF in loin muscles; and group 3(G3), the carcasses had 17% to < 18.5% IMF in loin muscles. These were used to evaluate the effects of gender and carcass group on quality traits and Warner–Bratzler shear force (WBSF) of Psoas major (PM), Longissimus thoracis (LT), Longissimus lumborum (LL), Longus colli (LC), Supraspinatus (SS), Latissimus dorsi (LAD), Semimembranosus (SM), Quadriceps femoris (QF), Biceps femoris (BF) and Semitendinosus (ST) muscles. Our results showed that pH values of LT, LL, LC, BF and QF muscles were lower in steers than in cows (P < 0.05). Water holding capacity (WHC) was found higher in LC, SS, LAD and QF muscles of steers (P < 0.05). At day 2 of ageing, gender affected the WBSF values of only PM, LD and QF muscles in G1, and QF muscle in G3; however, with additional ageing, the gender effect was observed for most of the muscles. Most muscles showed ageing responses; however, the rates of ageing response significantly varied depending on gender and carcass groups. The muscles of G1 and G2 had generally higher tenderization potentials than those of G3. Furthermore, most muscles in G3 had generally lower WBSF values than in G1 and G2. These results clearly indicate that ageing has a significant effect on quality and WBSF of beef muscles, and the classification by loin IMF level may be useful for prediction of the tenderness of other muscles.     

An insertion/deletion variant of a thymine base in exon 2 of the porcine beta 3‐adrenergic receptor gene associated with loin eye muscle area

An insertion/deletion variant of a thymine base (T5 and T6) in exon 2 of porcine beta 3‐adrenergic receptor (ADRB3) gene has been described. In the current study, we made an association study between the ADRB3 polymorphisms and production traits in 735 Duroc pigs. The allele frequencies for the T5 and T6 alleles in our study population were 0.433 and 0.567, respectively. Any associations between ADRB3 genotype and average daily weight gain during test period, or backfat thickness and intramuscular fat content were not detected in either sex. However the size of the loin eye muscle area (EMA) was significantly associated with ADRB3 genotypes in gilts. T6‐homozygous gilts had a higher mean of EMA (40.6 ± 0.6 cm²) than T5‐homozygous (38.1 ± 0.4 cm², P = 0.002) and heterozygous (38.8 ± 0.3 cm², P = 0.034) gilts. This association was not detected in males. In addition, a multiple traits animal model best linear unbiased predictor (BLUP) analysis revealed that the T6‐homozygous genotype had positive effects on breeding value of EMA. Accordingly, we suggest that ADRB3 polymorphism has the potential to be an important genetic marker for prediction of EMA in Duroc pigs.     

饲粮营养水平对猪背最长肌IMF含量及部分相关因子的影响

试验选用84头体重接近10 kg的杜洛克×长白×大约克三元杂交(DLY)阉公猪,随机分成2组,每组6个重复,每个重复7头猪。研究在NRC(1998)标(准对照组)和荣昌猪饲养标(准试验组)2种饲粮条件下,营养水平对DLY生长肥育期血液胰岛素、背最长肌IMFc、AMPI、R含量及ACC mRNA表达量的影响。结果表明:①荣昌猪饲养标准下,各阶段试验组背最长肌肌内脂肪含量均高于对照组,50kg时达到了显著水平(P<0.05)。②试验组背最长肌cAMP水平50kg时低于对照组(P<0.01);IR含量80kg时显著低于对照组(P<0.05)。     

Effects of deficiency and surplus dietary threonine on reproductive performance of primiparous pregnant gilts

Dietary threonine imbalance is known to impair reproductive performances of gestating sows, but the underlying mechanisms are largely unknown. In this study, effects of deficiency and surplus dietary threonine during gestation on reproductive performance, serum metabolites and hormones concentration, and colostral nutrient and immunoglobulin contents of primiparous sows were investigated. Ninety primiparous pregnant gilts were assigned to one of the three dietary treatments with different standardized ileal digestible threonine/lysine ratios at 0.59, 0.72 and 0.85, which represented deficient (DT), adequate (AT) and surplus (ST) dietary threonine concentration respectively. Maternal body weight gain from day 80–110 of gestation was highest (p < .05) for gilts fed AT than for gilts fed DT or ST. On days 30 and 110, serum threonine concentration increases in a dose‐dependent manner with the increasing of dietary threonine concentration in (p < .01), serum urea nitrogen concentration was lower (p < .01) in gilts fed AT than DT or ST, and serum insulin‐like growth factor‐I (IGF‐I) was lowest (p < .05) for gilts fed DT. On day 110, gilts fed AT had lower serum progesterone concentration but higher concentrations of serum prolactin (p < .05) compared to DT and ST. Concentration of colostral immunoglobulin A and G from gilts fed DT was lower (p < .05) compared with gilts fed AT or ST. In conclusion, gilts with the adequate threonine intake were more able to conserve dietary amino acids to support foetal and maternal tissue gain. Deficient or ST threonine intake may induce a delay in changes in progesterone and prolactin concentrations during the prepartum period impeding the transition from pregnancy to lactation.     

藏猪和大约克猪ACADM基因表达量与脂肪沉积性状的相关性分析

为探究中链酰基辅酶A脱氢酶(ACADM)基因在不同品种猪组织中的表达水平,并分析其与猪脂肪沉积性状的相关性,采用Sange测序法对藏猪(58头)和大约克猪(60头)ACADM基因起始密码子上游1 kb区域进行了单核苷酸多态性(SNPs)筛选与基因分型,选取180日龄藏猪和大约克猪各10头屠宰后分别采集肝脏、背脂、心脏和...     

Estimation of the optimal standardized ileal digestible lysine requirement for primiparous lactating sows fed diets supplemented with crystalline amino acids

This experiment was conducted to determine the optimal standardized ileal digestible lysine (SID Lys) level in diets fed to primiparous sows during lactation. A total of 150 (Landrace × Large White) crossbred gilts (weighing 211.1 ± 3.5 kg with a litter size of 11.1 ± 0.2) were fed lactation diets (3325 kcal metabolizable energy (ME)/kg) containing SID Lys levels of 0.76, 0.84, 0.94, 1.04 or 1.14%, through 28 days lactation. Gilts were allocated to treatments based on their body weight and backfat thickness 48 h after farrowing. Gilt body weight loss was significantly (P < 0.05) decreased by increasing dietary SID Lys levels. Fitted broken‐line (P < 0.05) and quadratic plot (P < 0.05) analysis of body weight loss indicated that the optimal SID Lys for primiparous sows was 0.85 and 1.01%, respectively. Average daily feed intake (ADFI), weaning‐to‐estrus interval and subsequent conception rate were not affected by dietary SID Lys levels. Increasing dietary lysine had no effect on litter performances. Protein content in milk was increased by dietary SID Lys (P < 0.05). Dietary SID Lys tended to increase concentrations of serum insulin‐like growth factor I (P = 0.066). These results of this experiment indicate that the optimal dietary SID Lys for lactating gilts was at least 0.85%, which approaches the recommendation of 0.84% that is estimated by the National Research Council (2012).     

Lysine restriction during grower phase on growth performance,blood metabolites,carcass traits and pork quality in grower finisher pigs

Abstract

The effects of lysine restriction during grower phase and realimentation during finisher phase on growth performance, nutrient digestibility, blood metabolites, carcass traits and pork quality were studied. Sixty-four pigs (two castrated males and two females per pen) weighing 34.34±5.22 kg were assigned to four dietary treatments. During grower (35–55 kg), pigs were fed isoenergetic lysine-restricted diets. The different lysine content of diets were 0.950 (NRC recommendation), 0.760, 0.665 and 0.570%, corresponding to lysine restriction of 20, 30 and 40%. Then all pigs were fed with common finisher 1 (55–85 kg) and 2 (85–115 kg) diets. Lysine restriction during the grower phase resulted in poor performance and lower concentration of blood metabolites but improved the nutrient digestibility and efficiency of lysine utilization. Compensatory growth response in terms of improved weight gain and feed efficiency was observed in pigs previously fed lysine-restricted diets during finisher 1, but the concentration of blood urea nitrogen and total protein were lower. No differences in growth performance, digestibility of nutrients and blood metabolites were noted during finisher 2. Lysine restriction of grower diets decreased the dressing percentage (quadratic, P=0.024), and protein content of longissimus muscle (linear P=0.034, and quadratic P=0.009). Thus, it could be concluded that pigs subjected to lysine restriction during grower phase exhibited compensatory growth responses in weight gain and improved efficiency of feed and lysine utilization for weight gain and lean accretion during finisher phase.     

Comparisons of carcass traits,meat quality,and serum metabolome between Shaziling and Yorkshire pigs

This study aims to compare the meat quality of Shaziling and Yorkshire pigs and to find the potential indicator in serum for superior meat quality. Six Shaziling and Yorkshire pigs at 30, 60, 90, 150, 210, and300 d of age were selected to examine carcass traits, meat quality, and serum metabolome. The results showed that the body weight, carcass length, and loin eye area of Shaziling pigs at 150, 210, and 300 d of age were significantly lower than those of Yorkshire pigs (P <0.05). Shaziling ...     

饲粮异亮氨酸水平对肥育猪生长性能、胴体性状和肉品质的影响

本试验旨在研究饲粮异亮氨酸水平对肥育猪生长性能、胴体性状和肉品质的影响。选取体重为(77.0±0.1)kg的杜×长×大三元杂交去势公猪72头,随机分为3组,每组6个重复,每个重复4头猪。3组试验猪分别饲喂含0.25%(低异亮氨酸水平,表现为异亮氨酸缺乏,L-Ile组)、0.39%(NRC推荐异亮氨酸水平,N-Ile组,作为对照组)和0.53%(高异亮氨酸水平,表现为异亮氨酸超量添加,H-Ile组)标准回肠可消化异亮氨酸的饲粮。试验期为28 d。结果表明:饲粮异亮氨酸水平对肥育猪的平均日增重和平均日采食量没有显著影响(P0.05),但L-Ile组料重比较对照组显著增加(P0.05);随着饲粮异亮氨酸水平的增加,肥育猪背最长肌肌内脂肪含量线性提高(P0.05),而剪切力线性下降(P0.05);与对照组相比,采食异亮氨酸缺乏饲粮的肥育猪的背膘厚、眼肌面积和肉色评分显著降低(P0.05),采食异亮氨酸缺乏或超量添加饲粮的肥育猪的热胴体重、屠宰率以及背最长肌滴水损失和黄度值均显著降低(P0.05);随着饲粮异亮氨酸水平的增加,血清甘油三酯含量线性提高(P0.05),血清尿素氮含量线性下降(P0.05);与对照组相比,采食异亮氨酸超量添加饲粮的肥育猪的血清葡萄糖含量显著增加(P0.05),采食异亮氨酸缺乏饲粮的肥育猪的血清中游离的必需氨基酸、非必需氨基酸和总氨基酸的浓度显著降低(P0.05),而采食异亮氨酸缺乏或超量添加饲粮的肥育猪血清总胆固醇、低密度脂蛋白和高密度脂蛋白含量均显著降低(P0.05)。由此得出,饲粮中异亮氨酸缺乏对肥育猪生长性能、胴体性状和肌内脂肪含量有负面影响,而超量添加异亮氨酸会显著改善肌肉的剪切力和滴水损失,增加肌内脂肪含量,但会以降低热胴体重、屠宰率为代价。     

Experimental Inoculation of Pregnant Swine with Type 1 Bovine Viral Diarrhoea Virus

The ability of bovine viral diarrhoea virus type 1 (BVDV‐1) to induce transplacental infection in pigs was evaluated. Control pigs (n = 4) were sham‐inoculated while infected pigs (n = 4) were intranasally inoculated with BVDV‐1 on day 65 of gestation. Blood samples were tested throughout the study for BVDV and antibody to BVDV. On day 110 of gestation, a Caesarean section was performed. Serum was obtained for virus isolation and antibody determination from all piglets, and all experimental animals were killed. Tissues were collected for virus isolation and histopathology. Bovine viral diarrhoea virus was isolated on days 5 and 7 after infection and seroconversion was demonstrated in all infected gilts; however, BVDV was only isolated from one fetus from an infected pig. Viraemia and seroconversion were demonstrated in the pregnant gilts; however, transplacental infection at day 65 of gestation in the pig was not consistently demonstrated.