Low birth weight is associated with enlarged muscle fiber area and impaired meat tenderness of the longissimus muscle in pigs

The objective of this study was to determine the relationships between birth-weight-associated modifications in histological or chemical muscle characteristics and meat quality traits in pigs. At 68 d of age, Pietrain x (Large White x Landrace) female littermates were allocated into 2 groups on the basis of low birth weight (LW = 1.05 +/- 0.04 kg; n = 15) or high birth weight (HW = 1.89 +/- 0.02 kg; n = 15). Pigs were reared in individual pens with free access to a standard diet up to slaughter at approximately 112 kg of BW. During the growing-finishing period, LW and HW pigs had a similar daily feed consumption, whereas G:F was lower (P = 0.009) for LW pigs than for HW littermates. At final BW, LW pigs were 12 d older (P < 0.001) than HW littermates. Estimated lean meat content, relative proportions of loin and ham in the carcass, and weights of LM and semitendinosus muscle (SM) were decreased (P < 0.05) in LW pigs compared with HW pigs. Conversely, the LW pigs exhibited a fatter carcass, greater activity levels of fatty acid synthase and malic enzyme in backfat (n = 15 per group), and enlarged subcutaneous adipocytes (n = 8 per group) compared with the HW pigs. Similarly, lipid content was increased by 25% (P = 0.009), and mean adipocyte diameter was 12% greater (P = 0.008) in the SM from LW pigs compared with that from HW pigs, whereas lipid content did not vary in the LM of either group. Mean myofiber cross-sectional areas were 14% greater in the LM (P = 0.045) and the SM (P = 0.062) of LW pigs than of HW pigs. Conversely, the total number of myofibers was less (P = 0.003) in the SM of LW vs. HW pigs. There were no differences between groups for glycolytic potential at slaughter and rate and extent of postmortem pH decline in both muscles, as well as for LM drip losses. A trained sensory test panel judged the roast loin meat to be less tender (P = 0.002) in LW pigs relative to HW pigs. Scores for juiciness, flavor, flouriness, and fibrousness of meat did not differ between groups. Overall, negative but somewhat low correlation coefficients were found between LM tenderness score and ultimate pH (r = -0.36; P = 0.06) and between LM tenderness and mean cross-sectional area of myofibers (r = -0.34; P = 0.07). This study demonstrates a lower tenderness of meat from pigs that had a LW, partly as a result of their enlarged myofibers at market weight.     

Increased maternal nutrition of sows has no beneficial effects on muscle fiber number or postnatal growth and has no impact on the meat quality of the offspring

The objective of this study was to examine how increased feed intake of the sow during early to mid-gestation affects sow performance and the muscle fiber number, performance, and technological meat quality of the offspring. Thirty-nine pregnant sows (Landrace x Large White sows mated to Landrace or Large White boars) in their fourth parity were assigned to one of three treatments: 1) the sows were either fed restrictively (control = 15 MJ of NE/d from d 1 to 90, then 24 MJ of NE/d from d 91 to 112, and again 15 MJ of NE/d from d 113 to 115 of gestation); 2) fed ad libitum from d 25 to 50 (A25-50); or 3) ad libitum from d 25 to 70 (A25-70) and as control in the remaining periods. The offspring were weaned at 4 wk of age and had free access to feed from 2 wk of age until slaughter. They were slaughtered litterwise at an average body weight of 104 +/- 14 kg. Estimates for total, primary (P-), and secondary (S-) muscle fiber number; muscle fiber area; and DNA and RNA content were analyzed in semitendinosus muscle (ST) samples from the heaviest, middle, and lightest weight (LW) pigs of each sex within litter selected at slaughter. Technological meat quality traits (pH at 24 h postmortem, drip loss, Minolta color, and pigment) were analyzed in longissimus dorsi muscle. Fiber number, fiber area, and concentrations and content of DNA and RNA of the offspring were not significantly affected by increased maternal nutrition. The ST muscle weight was lower in offspring from A25-50 than control sows (P = 0.019). Average daily gain, carcass weight, and the muscle deposition rate also were numerically lower for A25-50 than control and A25-70 pigs. An interaction between treatment and pig weight was found for muscle deposition rate (P = 0.006), in that LW pigs from treatment A25-50 had a lower deposition rate than LW pigs from control. We found no effect of treatment on the meat quality traits in the offspring. Also, barrows had a higher (P < 0.05) number of P-fibers, higher daily gain, and carcass weight than female pigs. No differences were found on any meat quality traits between sexes. Thus, ad libitum feeding of pregnant sows from d 25 to 50 or d 25 to 70 of gestation did not have any beneficial effect on muscle fiber number and area in the offspring. It seems that maternal ad libitum feeding from d 25 to 50 in gestation had a negative effect on postnatal muscle growth, with especially the LW pigs being affected.     

Increased sow nutrition during midgestation affects muscle fiber development and meat quality, with no consequences on growth performance

Pregnant sow nutrition has potential effects on the muscle fiber development of progeny in utero. A total of 199 Landrace x Large White sows from parities 0 to 6 and their offspring were used to evaluate the effects of increasing the feeding amount during midpregnancy on the muscle tissue, growth performance, and meat quality of the progeny. The experiment was divided into 2 study replicates, and in each replicate, sows were assigned to 1 of the 2 treatments: 1) sows in the control group (C sows) were fed 2.5 to 3.0 kg/d (feed: 12.1 MJ of ME/kg and 0.62% lysine) throughout gestation; and 2) sows in the high group (H sows) received an extra feed allowance of 1.5 kg/d for gilts and 2.0 kg/d for multiparous sows above the C amount from d 45 to 85 of gestation (period of secondary muscle fiber formation). Sow backfat was recorded on d 40 and 85 of gestation. Sow performance (litter size and piglet BW) at farrowing and on d 18 of lactation was measured. At weaning, pigs were divided into 5 BW groups/treatment, and progeny growth performance was measured during the nursery (n = 958) and the growing-finishing (n = 636) periods. At slaughter, carcass and meat quality traits (lean content, main cut weight, pH, Minolta color, and drip loss) were recorded from the second lightest group at weaning (BW group 4; n = 90), and samples from the longissimus thoracis muscle were taken to study muscle fiber characteristics (n = 70). The extra nutrition from d 45 to 85 of gestation did not lead to differences in litter size or piglet BW at farrowing and on d 18 of lactation. Pigs born to H mothers had fewer muscle fibers and fewer estimated primary and secondary fibers than did pigs born to C mothers (P < 0.05). However, postnatal growth performance was not consistently affected by the maternal treatment. The smaller number of muscle fibers found in the H group of pigs was associated with fewer type IIB fibers (P < 0.05) with greater cross-sectional areas (P < 0.10), which might be related to the significantly greater meat pH at 24 h postmortem and the smaller L* (lightness) values recorded in the H group of pigs. Results from the present study confirm the existence of effects of maternal nutrition on fetal development, at least in terms of muscle tissue development and meat quality, although with no beneficial effects were found for the postnatal growth performance of the progeny.     

Influence of rearing conditions on performance, behavioral, and physiological responses of pigs to preslaughter handling, carcass traits, and meat quality

A total of 120 crossbred [synthetic line x (Large White x Landrace)] pigs (castrated males and females) were used to evaluate the influence of rearing conditions for growing-finishing pigs on growth performance, carcass, stress reactions at slaughter, and meat eating quality. At approximately 35 kg of live weight (LW), littermates were allocated to either a conventional (fully slatted floor, 0.65 m2/pig, considered as control, CON) or an alternative (sawdust bedding with free access to an outdoor area, 2.4 m2/pig, OUT) system, until slaughter at approximately 110 kg of LW. Pigs had free access to standard growing and finishing diets. The trials were conducted in spring, summer, and winter, with each season involving 2 pens of 10 pigs in each system. Compared with the CON, the OUT pigs exhibited a greater growth rate (+10%, P < 0.001) due to their greater feed intake (+0.23 kg/d, P < 0.01), resulting in a greater body weight at slaughter (+7 kg, P < 0.001). The OUT pigs had thicker backfat (+2.4 mm, P < 0.01) and lower lean meat content (- 2.0% points, P < 0.001) than the CON pigs. The OUT system did not (P > 0.10) influence the behavioral activities of pigs during lairage at the slaughterhouse, or the urinary levels of catecholamines and cortisol, and plasma levels of ACTH, cortisol, lactate, creatine kinase, and FFA immediately after slaughter. The OUT pigs had similar (P > 0.10) pH values 30 min postmortem (pH1) in the LM, biceps femoris (BF), and semimembranosus (SM) muscles, similar ultimate pH (pHu) in LM, but lower pHu in SM (- 0.07 unit, P < 0.001) and in BF (- 0.03 unit, P = 0.029). Despite nonsignificant effects of production system on stress reactions at slaughter, assessed by urine and plasma indicators and muscle metabolism at 30 min postmortem, meat from OUT pigs had more LM drip loss after 2 (+1.0%, P = 0.003) and 4 (+1.1%, P = 0.010) d than did meat from the CON pigs. The OUT system slightly increased meat yellowness (b* value) in the LM (+0.7 unit, P = 0.001), BF (+0.5 unit, P = 0.014), and SM (+0.5, unit P = 0.041), whereas redness (a*) and lightness (L*) of the 3 muscles were unaffected (P > 0.07). Intramuscular fat content was greater in the LM (+17%, P = 0.001), BF (+14%, P = 0.004), and SM (+17%, P = 0.003) of the OUT pigs. Outdoor rearing during summer and winter improved meat juiciness, whereas odor, flavor, and tenderness were unaffected (P > 0.10). Influence of rearing conditions on all the other traits studied did not depend on the season.     

自然放牧方式下欧拉羊羊肉中矿物元素、脂肪酸及氨基酸含量分析

为研究典型草原放牧欧拉羊体肌肉中矿物元素、脂肪酸和氨基酸的含量,本试验随机选取同一群体18月龄欧拉羊羯羊20只,测定欧拉羊体重、屠宰性能及背最长肌中矿物元素、脂肪酸、胆固醇、维生素E及氨基酸含量。结果表明:群体中体重在40 kg以下(LW组)占25%,40~50 kg(MW组)占45%,50 kg以上(HW组)占30%;HW组屠宰率、净肉率和眼肌面积均显著高于MW组和LW组;肌肉中铁含量为7.76~8.07 mg/100g,锌含量为10.06~10.74 mg/100g,HW组背最长肌锰含量显著低于LW组;胆固醇含量为36.57~43.43 mg/100g,n-6/n-3为2.12~2.21,HW组胆固醇含量及单不饱和脂肪酸与饱和脂肪酸的比值(M/S)显著高于MW组和LW组;维生素E含量丰富,为0.31~0.40 mg/100g,各组间差异不显著;3组的氨基酸相对含量差异不显著。综上可知,青海地区天然放牧的欧拉羊肌肉中铁、锌等矿物元素及维生素E含量较高,体重在50 kg以上维生素E含量更高且屠宰性能更好。天然放牧的欧拉羊肌肉中n-6/n-3比值较低,更符合人类健康的需求。     

Live weights at slaughter significantly affect the meat quality and flavor components of pork meat

One‐hundred‐twenty crossbred pigs finished at 175–185 days of age were used to investigate the effects of live weights at slaughter on the meat quality, volatile flavor compounds, and sensory attributes of pork meat. Based on the live weights at slaughter, three weight groups (n = 36 per group) were classified as follows: light weight (LW: 100 kg), medium weight (MW: 110 kg), and heavy weight (HW: 120 kg). After slaughter, longissimus dorsi muscle samples were taken and used for the analyses of aforementioned parameters. The HW group had higher fat content and water holding capacity compared to the LW or MW group (p < 0.05). The HW group also showed higher levels for majority of unsaturated fatty acids and total polyunsaturated fatty acids than the LW group (p < 0.05). The slaughter weight significantly affected the amounts of 11 among the 47 flavor compounds identified. Significantly higher amounts of fatty acids oxidation‐derived flavor compounds (aldehydes) were found in the HW group than in the other groups. Noticeably, increasing slaughter weight was associated with higher sensorial scores for flavor, juiciness, and acceptance scores (p < 0.05). Based on the obtained results, 120 kg body weight is recommended as the market weight for this commercial breed without compromising the meat quality.     

Effect of early gestation feeding, birth weight, and gender of progeny on muscle fiber characteristics of pigs at slaughter

Maternal nutrition and progeny birth weight affect muscle fiber development in the pig, thereby influencing early postnatal growth rate. The objective of the study was to determine the extent to which growth, morphometric characteristics, and area and distribution of slow-oxidative (SO), fast oxidative-glycolytic (FOG), and fast glycolytic (FG) fibers of three muscles (LM = longissimus muscle; RF = rectus femoris; ST = semitendinosus) of slaughter pigs were affected by DE intake level during the first 50 d of gestation. Multiparous Swiss Large White sows were assigned randomly to one of three energy intake treatments: 1) fed 2.8 kg/d of a standard diet (STD; n = 6) containing 10.7 MJ DE/kg; 2) fed 2.8 kg/d of a low-energy diet (LE; n = 5) containing 6.6 MJ DE/kg; or 3) fed 4.0 kg/d of a standard diet (HE; n = 5) containing 10.7 MJ DE/kg (as-fed basis). Sows were subjected to energy intake treatments for the first 50 d of gestation; however, from d 51 to parturition, sows received 2.8 kg/d of the standard diet, and the amount of feed offered each sow during lactation was adjusted according to the litter size. Sows farrowed normally and pig birth weights were recorded. Based on birth weight, the two lightest (1.27 kg; Lt) and two heaviest (1.76 kg; Hvy) barrows and gilts from the 16 litters (n = 64) were selected at weaning and were offered a fixed amount of feed (170 g x BW(0.569)/d) from 25 to 105 kg BW. Regardless of the birth weight, progeny from HE sows grew slower (P < 0.05) during lactation and the growing-finishing period, had a lower (P < 0.05) gain-to-feed ratios, and had higher (P < 0.05) percentages of adipose tissue than pigs born from LE sows. The ST was shorter (P = 0.03) in Lt than in Hvy pigs, and the ST of gilts was heavier (P = 0.01) and had a larger (P = 0.01) girth than the ST of barrows. Overall mean fiber area tended to be larger (P < or = 0.11) in the LM and light portion of the ST of Lt than in Hvy pigs, and was larger (P = 0.03) in the ST of gilts than barrows. The ST of progeny from LE sows had fewer (P < 0.10) FG fibers, which was compensated by either more (P < 0.05) FOG in the light portion of the ST, or more (P < 0.10) SO fibers in the dark portion, and these differences were more pronounced in Lt pigs than in Hvy pigs. Overall, maternal feeding regimen affected muscle fiber type distribution, whereas birth weight and gender affected muscle fiber area.     

育肥猪粪便菌群结构及其与生长速度的相关性分析

【目的】 研究育肥猪的生长速度与粪便微生物之间的作用关系，寻找与猪生长速度相关的微生物菌群。【方法】 选取50头出生重相近的仔猪，在相同饲养环境中进行饲养管理，生病猪及时转出试验组，125日龄时按体重由高到低排序，把体重最高和最低的4头猪分别分为体重高（51.30 kg±2.57 kg，HW）、低（36.90 kg±2.50 kg，LW）组，通过16S rRNA测序，对125日龄生长育肥猪的粪便微生物区系多样性、群落组成及与生长速度的关联性进行分析。【结果】 Alpha多样性分析显示，两组间均无显著差异（P>0.05）。主成分分析结果显示，HW和LW组中能够明显区分菌群结构。粪便微生物结构组成分析表明，HW和LW组的优势菌门均为厚壁菌门、拟杆菌门和螺旋体门，优势菌属为密螺旋体属、乳杆菌属、链球菌属和未被培养菌属Muribaculaceae菌。LW组中拟杆菌门丰度极显著高于HW组（P<0.01），纤维杆菌门丰度显著高于HW组（P<0.05），而髌骨细菌门丰度显著低于HW组（P<0.05）。对粪便微生物结构组成进行差异分析发现，HW组检测到16个特有菌门，LW组检测到1个特有菌门和24个特有菌属。将肠道菌群与生长速度进行相关性分析，共发现10个菌门，18个属与体重（BW）和平均日增重（ADG）呈正相关，7个菌门和12个属与BW和ADG呈负相关。【结论】 相同日龄不同生长速度的猪粪便微生物的区系结构存在显著差异，差异菌群可能对猪的生长速度起到了一定的调控作用，本研究结果为研发益生菌和提高猪生长速度提供了参考依据。     

Environmental effects on pig performance, meat quality, and muscle characteristics

The objective of this experiment was to determine the effect of diverse production systems on pig performance, muscle characteristics, and their relation to pork quality measures. Birth and rearing conditions were evaluated using 48 barrows during the fall/winter months. Pigs were farrowed in either indoor crates or outdoor huts. At weaning, indoor- and outdoor-born pigs were allotted randomly to treatments arranged in a 2 x 2 factorial design with two birth (indoor vs. outdoor) and rearing (indoor vs. outdoor) environments. Pigs housed indoors were on concrete-slatted flooring (1.2 m2/pig), and pigs housed outdoors were on an alfalfa pasture (212 m2/pig). Body weight data were collected. Muscle samples were removed within 1 h postmortem from the longissimus (LM) and semimembranosus (SM) muscles. Muscle samples were stained histochemically to identify type I, IIA, and IIB/X muscle fibers. Boneless loins were collected from the left side of each carcass and aged for 14 d. Objective and subjective color measurements were taken on the longissimus muscle at the 10th rib on d 14 postmortem. Loin chops were evaluated for sensory attributes, shear force, and retail display features. Pigs born outdoors were heavier and had a greater ADG at most growth intervals postweaning (d 28, 56, and 112; P < 0.05) than pigs born indoors. Pigs reared outdoors were heavier (P = 0.02) at d 140 (120.1 vs. 112.9 +/- 4.9 kg), and had higher (P = 0.01) ADG (2.2 vs. 1.9 kg/d) and gain:feed ratios (0.41 vs. 0.37) than did pigs reared indoors. Birth x rearing environment interactions were not significant (P > 0.10) for most measures. Carcass and meat quality measures did not differ (P > 0.05) among treatment groups, but loin chops from outdoor born or reared pigs had higher (P < 0.05) a* values than chops from pigs born or reared indoors. The LM muscle of pigs born outdoors had a higher (P < 0.01) percentage of type I, and a lower (P < 0.05) percentage of type IIA fibers than did pigs born indoors. Pigs reared outdoors had a higher (P < 0.01) percentage of IIA fibers and a lower (P < 0.05) percentage of IIB/X fibers than did pigs reared indoors for the LM and SM muscles. Outdoor production systems may influence growth, pork color, and muscle fiber types.     

Growth,carcass, fiber type,and meat quality characteristics in Large White pigs with different live weights

The aim of this study was to compare the growth, carcass, histochemical, and meat quality characteristics in Large White pig groups that were categorized by live weight (Heavy and Light) and type I fiber percentage (High and Low), a procedure which resulted in four groups (Heavy-High, Heavy-Low, Light-High, and Light-Low). As expected, the Heavy group showed heavier live weight (114 vs. 94.7 kg, P<0.001) and larger loin eye area (53.3 vs. 47.8 cm², P<0.001), as well as, higher total number (1,223,000 vs. 1,140,000, P<0.05) and greater mean value cross-sectional area (CSA; 4031 vs. 3798 μm²P<0.05) of muscle fibers than the Light group. However, there were no significant differences in start and finish days among the groups (P>0.05). Heavier pigs harboring a higher percentage of type I fibers (HH) exhibited a similar mean CSA (3894 vs. 4101 μm²) and total number (1,249,000 vs. 1,198,000) of muscle fibers, even though these pigs had a greater CSA of type I fibers (3181 vs. 2719 μm², P<0.05) and a smaller CSA of type IIB fibers (4048 vs. 4457 μm², P<0.05) compared to heavier pigs harboring a lower percentage of fiber type I (HL). Both the HL and Light-Low groups exhibited a rapid decline of muscle pH at the early postmortem period (5.90 and 5.85 vs. 6.08, P<0.05), paler surfaces (43.07 and 43.55 vs. 40.73_,P<0.05), and higher degrees of fluid loss by exudation (6.26 and 6.39 vs. 4.22%, P<0.05) compared to the HH group due to their muscle fiber type composition. Thus, the HH pigs showed better meat quality characteristics without significant differences in growth and carcass performance compared to the HL pigs. Therefore, selection for increased live weight at the same age and muscle fiber characteristics, especially the increased type I fiber CSA and proportion, is one of the relevant indicators to improve and control meat quality without reducing the growth and carcass performance.     

Production,performance, slaughter characteristics,and meat quality of Ziwuling wild crossbred pigs

Wild boars, because of their large size and ability to survive adverse conditions, are usually used to cross with domestic breeds to improve the quality of domesticated pigs. This study aimed to investigate the growth performance, slaughter performance, and meat quality of Ziwuling crossbred pigs. Crossbred pigs in four groups (n = 8 per group, 4 boars and 4 sows, all aged 100 days), F₁ [wild × B (Bamei)], F₁ × B, F₁ × Y (Yorkshire), and F₁ × F₁, were selected at a commercial pig farm. Growth performance, slaughter performance, and meat quality of these crossbred pigs were determined. Characteristics of fatty acids, amino acids, and longissimus muscle fiber in relation to growth, carcass, and meat quality traits were also investigated. Pigs in F₁ and F₁ × F₁ groups had lower average daily weight gain, water and storage loss rates, larger meat color score, higher muscle amino acid levels, larger muscle fiber diameter, and higher ratio of flavor amino acids to unsaturated fatty acids compared to other groups. Crossbred pigs with higher rate of wild boar’s consanguinity could improve production performance, slaughter performance, and meat quality. Thus, crossbreeding wild pig with domestic breeds might be an effective method to improve meat quality and flavor.     

Carcass, muscle and meat characteristics of lean and obese pigs

Six pigs obtained from a lean selected strain and six pigs obtained from an obese selected strain were slaughtered at about 110 kg live-animal weight. Carcasses were evaluated; hams were dissected into bone, skin, fat and lean, and loin samples were obtained for fiber type characteristics, percentage of fat and moisture, collagen analysis, sensory characteristics, textural properties and objective color analysis. Carcasses from lean pigs were longer, had less backfat and larger longissimus muscle cross-sectional areas than carcasses obtained from obese pigs. Hams from lean pigs had less fat, more bone and more lean than hams from carcasses of obese pigs. The percentages and cross-sectional areas of red and white muscle fibers of the longissimus muscle from lean and obese pigs were not different. However, lean pigs had intermediate fibers that were only 79% as large (P less than .10) as intermediate muscle fibers from obese pigs. Intermediate fibers represented only 7 and 10% of total fiber area, whereas white fibers represented 84 and 79% of total fiber area in longissimus muscle of lean and obese pigs, respectively. Overall, lean pigs tended to possess fewer fibers (-16%) per unit of area than obese pigs, indicating that total muscle fiber hypertrophy was partially responsible for the increased longissimus muscle area of the lean strain. Sensory properties of longissimus meat samples from lean and obese strains were not different. However, the shear force requirement of the longissimus samples from the lean strain were slightly, but significantly (P less than .10), higher than those from the obese strain. No differences were observed in meat color.     

饲粮纤维源对育肥猪生长性能、胴体组成和肉品质的影响

本文旨在探讨不同纤维源对育肥猪生长性能、胴体组成和肉品质的影响.试验选用125头初始体重为(48.88±0.81) kg健康“杜×长×大”三元杂交生长肥育猪,随机分为5组,每组5个重复,每个重复5头猪,分别饲喂基础饲粮(对照组)以及添加玉米纤维、大豆纤维、小麦麸纤维和豌豆纤维的4种试验饲粮,饲粮纤维的添加量为30％.试验猪体重约为100kg时结束试验.结果表明:1)与对照组相比,大豆纤维组猪的末重和平均日增重显著降低(P＜0.05),大豆纤维组、小麦麸纤维组和豌豆纤维组猪的平均日采食量极显著降低(P＜0.01),小麦麸纤维组和豌豆纤维组猪的料重比显著降低(P＜0.05).2)饲粮中添加4种纤维有降低猪屠宰率的趋势(P=0.06),但对猪的胴体斜长和眼肌面积无显著影响(P＞0.05);而大豆纤维组、小麦麸纤维组和豌豆纤维组猪的平均背膘厚显著低于对照组(P＜0.05).3)饲粮中添加4种纤维有增加猪背最长肌中粗蛋白质含量的趋势(P=0.07),但对背最长肌PH45min亮度值、大理石纹评分和剪切力均无显著影响(P＞0.05);与对照组相比,豌豆纤维组猪的背最长肌pH24h显著提高(P＜0.05),背最长肌滴水损失显著降低(P＜0.05);而大豆纤维组和小麦麸纤维组猪背最长肌肌内脂肪含量显著降低(P＜0.05).本研究提示,饲粮中不同的纤维来源会对育肥猪的生长性能、胴体组成和肉品质产生不同程度的影响,其中,豌豆纤维对保障育肥猪的生长性能、改善肉品质的效果较好.     

The effects of selection of pigs on growth rate vs leanness on histochemical characteristics of different muscles

The microstructure of two type of muscles was studied in a selection experiment conducted with Dutch Large White pigs (boars and gilts) selected for either low backfat thickness (L-line) or fast growth (F-line). Second- and fourth-generation pigs were used to determine effects of selection on fiber type composition, fiber area, and capillary density in the longissimus lumborum (LL) and biceps femoris (BF) muscles. Immediately after slaughter samples were taken from the LL and BF muscles. The latter was divided into an inside (BFi) and outside (BFo) portion, which refer to the red and white portions of the biceps femoris. Serial sections were stained for ATPase (pH 4.60), succinate dehydrogenase (SDH), and alpha-amylase-periodic acid shiff (PAS) to determine fiber type and capillary density. The LL and BFo muscles had predominantly type IIBw fibers, whereas the BFi muscle had a 2 to 4 times higher amount of type I fibers. In most muscles there were more type I and fewer type IIBw fibers in F- than in L-line pigs (P < .05), except in the LL muscle of second-generation pigs and in the red part of the BF muscle of fourth-generation pigs. In both selection lines lower type I and higher type IIBw percentages were found in muscles from gilts than in those from boars (P < .05). Capillary density and fiber area of L- and F-lines showed minor differences, which could be explained by differences in weight and age of the pigs of both lines. The results suggest that selection for low backfat thickness in pig breeding compared with increased growth rate resulted in fewer oxidative and more glycolytic muscle fibers. The magnitude of the effect depended on muscle type and duration of the selection period.     

Effects of exogenous porcine somatotropin administration between 30 and 60 kilograms on longissimus muscle fiber morphology and meat tenderness of pigs grown to 90 kilograms

Twenty-four barrows were used to investigate the effects of exogenous porcine somatotropin (pST) administration (0 and 100 micrograms.kg-1.d-1) between 30 and 60 kg on longissimus muscle morphology and meat tenderness of pigs grown to 90 kg. Administration of pST was by daily i.m. injection. Pigs were fed a fortified diet in restricted amounts between 30 and 60 kg and had ad libitum access to this diet from 60 to 90 kg. Excipient pigs had fewer alpha R fibers and more alpha W fibers than pST-treated pigs (P less than .05). Administration of pST increased (P less than .05) muscle fiber area for all three fiber types at both the 60 kg (34%) and 90 kg (29%) slaughter weights. Furthermore, pST administration increased shear-force (30% at 60 kg; 19% at 90 kg) of the longissimus muscle, indicating that pST administration reduced meat tenderness. All the pST-treated pigs exhibited the "giant fiber syndrome" and a high proportion (62%) of pST-treated pigs exhibited pale, soft, exudative muscle. Whether the giant fiber anomaly resulted from increased muscle protein accretion rate or fiber degeneration is unknown. Results indicated that the stimulatory effects of pST on muscle growth are sustained following cessation of hormone treatment. However, the incidence of pale, soft, exudative muscle in 62% of the pST-treated pigs indicates that pST potentially has undesirable side effects.     

淮猪及杂交后代肌纤维直径变化及其与肉质关系的研究

对不同品种和杂交组合肥育猪(淮猪、长淮、大长淮)采用单因子试验设计,在相同条件下,研究不同血缘比例对淮猪肌纤维直径的影响。结果表明:淮杂猪的背最长肌和股二头肌肌纤维直径显著高于淮猪(P<0.05)。淮猪的肌纤维直径介于中国地方猪与国外瘦肉型猪之间。肌纤维直径与胴体性状(瘦肉率、眼肌面积、背最长肌全重、背最长肌率、脂肪)呈较强的相关性。淮杂猪肉质理化性状中(肉色评分、大理石纹评分、贮藏损失)3项指标明显变差(P<0.05),但pH值变化不显著。作者认为淮猪杂交后代的肌纤维直径较纯种淮猪粗,淮杂猪肉质也较纯种淮猪差。     

Developmental changes in morphometry of the small intestine and jejunal sucrase activity during the first nine weeks of postnatal growth in pigs

The objective of this study was to investigate the development of small intestinal size and digestive capacity of the jejunum in growing pigs. The weight, length, surface area, and mucosa weight of the small intestine were measured when pigs were 1, 3, 5, and 9 wk of age. Sucrase and alkaline phosphatase (ALP) activities of the jejunal brush-border membrane, prepared by differential centrifugation and Mg2+ precipitation, were determined at the respective postnatal stages. Body weights increased 7-fold from 2.7 kg at 1 wk to 23.32 kg at 9 wk postnatal. Body weight gains were greater (P < 0.05) from wk 3 to 5 than from wk 1 to 3. Weights of the small intestine and of the intestinal mucosa increased faster (P < 0.05) from 3 to 5 wk than from 1 to 3 wk; the slowest increase occurred from 5 to 9 wk. Weights of the duodenum, jejunum, and ileum, and mucosa from the respective sections increased (P < 0.05) as pigs grew from 3 to 9 wk. Mucosa weight relative to the weight of the section was greater (P < 0.05) for the duodenum and jejunum than for the ileum at 9 wk of age. Between the ages of 3 and 9 wk, the increase in mucosa weight was highest for the jejunum followed by the duodenum and the ileum. The increase was greatest for the duodenum followed by the jejunum and the ileum when mucosal weight was expressed per unit of appropriate intestinal section weight. There was a 55-fold increase in jejunal sucrase activity from 1 to 9 wk; the greatest rate of increase occurred between 5 and 9 wk. Total jejunal ALP activities in pigs at 9 wk was greater (P < 0.05) than at 5 wk, which in turn was greater than at 1 wk of age. In summary, increases in BW during the first 9 wk of postnatal growth in pigs are accompanied by significant developmental changes in digestive capacity including intestinal weights, length, and area as well as jejunal brush-border sucrase and ALP activities.