Effects of ractopamine on genetically obese and lean pigs

Twenty-eight genetically obese and 24 lean barrows (65.0 and 68.7 kg average BW, respectively) were allotted within genotype to a 16% CP corn-soybean meal basal diet or this basal diet + 20 ppm ractopamine (a phenethanolamine beta-adrenergic agonist) and allowed ad libitum access to feed for 48 d. Compared to lean pigs, obese pigs had lower ADG, gain to feed ratio, longissimus muscle area, predicted amount of muscle, and weights of trimmed loin and ham, ham lean, heart, spleen, kidney and gastrointestinal tract (P less than .05). Obese pigs also had shorter carcass but higher dressing percentage, backfat thickness, fat depth, fat area, untrimmed loin weight and fasting plasma urea N concentration (P less than .05). Dietary supplementation with 20 ppm ractopamine reduced daily feed intake and improved gain to feed ratio in both lean and obese pigs (P less than .05). Pigs fed ractopamine had shorter carcasses, less fat depth and fat area, smaller weights of stomach and colon plus rectum, but higher dressing percentages, longissimus muscle areas, weights of trimmed Boston butts, picnics and loins, ham lean and predicted amounts of muscle than pigs not fed ractopamine (P less than .05). Supplemental ractopamine had no effect on fasting plasma concentrations of urea N, nonesterified fatty acids, triglyceride or glucose (P greater than .05). No genotype x ractopamine interactions for the criteria described above were detected (P greater than .05). These results suggest that ractopamine will improve the efficiency of feed utilization and carcass leanness in swine with different propensities for body fat deposition.     

Differential compensatory growth in swine following control of feed intake by a high-alfalfa diet fed ad libitum or by limited feed

Seventy-two castrated male four-way composite (Chester White x Landrace x Large White x Yorkshire) weanling pigs (17 kg initial BW) were used to determine the compensatory response of specific organs and whole body following a 3-wk period of restricted energy intake imposed by ad libitum-feeding an 80% alfalfa meal diet or pair-feeding an adequate corn-soybean meal diet to attain equal weight loss. Six pigs were killed at d 0 to provide baseline data. Six pigs from each diet group (control, C; alfalfa, A, restricted, R) were killed at d 21, after which all remaining pigs were fed C ad libitum to 35 d, 105 d or 126 d. Six pigs per group were killed at 35 and 105 d and four per group were killed at 126 d. Organ weight and carcass data were recorded for all pigs at all time intervals. Regression of organ and trimmed lean tissue weights on time was tested for linearity (d 1 to 126 for C and d 21 to 126 for A and R except d 35 to 126 for gastrointestinal tract traits for A and R); differences in organ weights between C, A and R at d 21 and d 35 were tested by a two-way analysis of variance. There was no evidence of a compensatory growth response to dietary energy restriction for 21 d except for rate of change in weights of liver and kidneys and backfat depth from 21 to 126 d and of gastrointestinal tract components from 21 to 35 d. Specific organs may exhibit compensatory growth over different time spans in young pigs in the absence of observable weight compensation at the whole-animal level.     

Effects of dietary fiber of young adult genetically lean, obese and contemporary pigs: rate of passage, digestibility and microbiological data

Twenty-one genetically lean, obese or contemporary slaughter weight castrated male pigs (6 mo old; seven of each genotype) were assigned to individual tether stalls and fed either a control diet (low fiber) or a diet containing 80% alfalfa meal (high fiber) at 1.50% of initial body weight for 71 d (1.75% for d 1 to 4). Apparent dry matter digestibility of the diets was estimated by determining acid insoluble ash in fecal samples. Fecal cellulolytic bacteria and total viable bacteria were enumerated at d 0, 14, 35, 49 and 70. Fecal inocula were used to determine 48-h in vitro digestibility of alfalfa meal fractions on the same days. Digesta rate of passage was determined by feeding a pulse dose of chromium-mordanted alfalfa fiber to the pigs fed the high-fiber diet. In vivo digestibility of both diets was less for the obese pigs than for the lean or contemporary genotypes. In vitro digestibility of alfalfa fiber fractions was not different between the genotypes fed either diet. When the high-fiber diet was fed, in vitro digestibility increased for all genotypes from d 0 to d 14, but not thereafter. The numbers of cellulolytic bacteria for all three genotypes were greater when pigs were fed the high-fiber diet (23.0 X 10(8), 51.6 X 10(8), 37.2 X 10(8) per gram fecal dry weight; obese, lean and contemporary, respectively) compared to the low-fiber diet (3.0 X 10(8), 3.2 X 10(8), 3.4 X 10(8), respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

日粮类型对猪肌肉组织HSL mRNA和Obese mRNA基因表达的影响

选用20 kg左右的"杜×长×大"外三元杂交仔猪20头,随机分为2组,分别饲喂豆粕型和杂粕(双低菜籽粕+豆粕)型2种不同类型的日粮,饲养猪至体重达到100 kg左右时屠宰测定瘦肉率,取背最长肌肌肉组织,采用RT-PCR技术检测分析HSL mRNA和Obese mRNA表达情况,以探索出日粮类型与基因表达的关系。结果显示,杂粕日粮较豆粕日粮可显著增加HSL mRNA表达量、减少Obese mRNA表达量(P<0.05),2种日粮类型虽对猪瘦肉率无显著性影响,但是从实际值来看,杂粕日粮表现出提高趋势,较豆粕日粮提高3.5%(P>0.05)。     

Use of carbohydrate and fat as energy source by obese and lean swine

Genetically obese and lean pigs were fed isonitrogenous-isoenergetic (digestible energy) amounts of a high or low fat diet from 25 kg body weight. Obese pigs gained less and required more feed per unit gain than lean pigs. Lean pigs were more muscular with less fat than obese pigs. Obese pigs utilized more dietary amino acids for energy (greater plasma urea N) than did lean pigs. Weight gain was similar at all intermediate periods in obese pigs fed the two diets. However, gain tended (P less than or equal to .10) to be greater and the ratio of dietary energy intake to gain tended (P less than or equal to .10) to be less in obese pigs fed high compared with low fat diets. Similar results were observed in lean pigs fed the two diets. The high fat diet produced more carcass adipose tissue deposition in both strains after 20 wk of feeding (detectable by ultrasound at 14, but not at 7 wk). Adipose tissue lipogenic rate (glucose incorporation) was similarly depressed by fat feeding in both obese and lean pigs. Obese and lean pigs both utilized dietary carbohydrate and fat differentially but there was no indication of genetic divergence regarding this utilization. In both strains of pigs, energy from the fat-enriched diet was preferentially partitioned into carcass adipose tissue.     

Plasma thyroid hormones, growth and carcass measurements of genetically obese and lean pigs as influenced by thyroprotein supplementation

A 2 X 2 factorial arrangement with two genotypes of pigs (genetically obese and lean) and two dietary treatments (basal, a 16% protein corn-soybean meal standard grower diet, and basal +220 ppm thyroprotein as iodinated casein) was used. The 28 gilts were housed individually and fed ad libitum from 121 d of age until slaughtered at 99 kg body weight. Compared with lean pigs, genetically obese pigs had significantly lower average daily gain and gain/feed, greater backfat thickness, smaller loin eye area, shorter carcass length and lower circulating plasma triiodothyronine (T3) concentration. However, both total plasma and free thyroxine (T4) concentrations were similar comparing obese and lean pigs. Supplementation with thyroprotein increased circulating plasma concentration of both total and free T4 and produced interactions with genotype in affecting daily gain and gain/feed of pigs. Thyroprotein reduced both daily gain and gain/feed in obese pigs, but increased daily gain and gain/feed in lean pigs. It is suggested, similar to the case with obese mice, that heat production of our genetically obese pigs may be more sensitive to thyroprotein administration compared with similar treatment of lean animals.     

Growth performance and carcass traits of pigs subjected to marginal dietary restrictions during the grower phase.

Sixty-four individually housed pigs were used to investigate the effect of amino acid content of finisher diets on growth performance of pigs subjected to marginal dietary amino acid restrictions (80% of the 1988 NRC lysine recommendation) during the grower phase. In each of the two trials, low- and high-amino-acid grower diets (.421 and .765 g lysine/MJ DE, respectively) and four finisher diets (.421, .516, .612, and .707 g lysine/MJ DE) were randomly assigned within sex to 16 gilts and 16 castrated males weighing 23.0 +/- 2.0 kg in a 2 x 4 factorial arrangement of treatments. The average weight of pigs after a completion of diet change was 50.4 +/- 2.1 kg. All pigs were slaughtered at an average weight of 105.2 +/- 4.1 kg. Ultrasound backfat thickness was measured at the time of diet change and before slaughter. Pigs were allowed ad libitum access to feed and water. During the grower phase, pigs fed the high-amino-acid diet grew faster (P < .001) and more efficiently (P < .001) and had less ultrasound backfat (P < .001) than those fed the low-amino-acid diet. The grower diet had no effect on weight gain during the finisher phase. Consequently, pigs fed the high-amino-acid grower diet had better overall weight gain (P < .01) than those fed the low-amino-acid diet. The rate of lean accretion was, however, similar between the two groups of pigs. Furthermore, pigs fed the low-amino-acid grower diet seemed to have better carcass quality, as indicated by less ultrasound backfat (P < .01) and larger carcass longissimus muscle area (P < .05). Average and 10th rib carcass backfat decreased linearly (P < or = .05) and lean accretion rate improved linearly (P < .05) as the amino acid content of finisher diets increased, but there was no grower x finisher diet interaction in these and other response criteria. Although no evidence of compensatory weight gain was observed, it is possible that compensatory lean tissue growth may have occurred in pigs subjected to early amino acid restrictions at the expense of fatty tissue growth.     

Soybean meal from roundup ready or conventional soybeans in diets for growing-finishing swine

Dehulled soybean meal prepared from genetically modified, herbicide (glyphosate)-tolerant Roundup Ready soybeans containing the CP4 EPSPS protein and near-isogenic conventional soybeans were assessed in an experiment with growing-finishing pigs. The soybeans were grown in the yr 2000 under similar agronomic conditions except that the Roundup Ready soybeans were sprayed with Roundup herbicide. Both were processed at the same plant. The composition of the two types of soybeans and the processed soybean meal were similar. Corn-soybean meal diets containing conventional or Roundup Ready soybean meal and fortified with minerals and vitamins were fed to 100 cross-bred pigs from 24 to 111 kg BW. Diets contained approximately 0.95% lysine initially and were reduced to 0.80 and 0.65% lysine when pigs reached 55 and 87 kg BW, respectively. There were 10 pens (five pens of barrows and five pens of gilts) per treatment with five pigs per pen. All pigs were scanned at 107 kg mean BW and all barrows were killed at the end of the test for carcass measurements and tissue collection. Rate and efficiency of weight gain, scanned backfat and longissimus area, and calculated carcass lean percentage were not different (P > 0.05) for pigs fed diets containing conventional or Roundup Ready soybean meal. Gilts gained slower, but they were more efficient and leaner (P < 0.05) than barrows. Responses to the type of soybean meal were similar for the two sexes with no evidence of a diet x sex interaction for any of the traits. In most instances, carcass traits of barrows were similar for the two types of soybean meal. Longissimus muscle samples from barrows fed conventional soybean meal tended (P = 0.06) to have less fat than those fed Roundup Ready soybean meal, but water, protein, and ash were similar. Sensory scores of cooked longissimus muscles were not influenced (P > 0.05) by diet. The results indicate that Roundup Ready soybean meal is essentially equivalent in composition and nutritional value to conventional soybean meal for growing-finishing pigs.     

Organ weight, intestinal morphology, and fasting whole-body oxygen consumption in growing pigs fed diets containing distillers dried grains with solubles alone or in combination with a multienzyme supplement

The effects of adding a multienzyme complex to a diet containing distillers dried grains with solubles (DDGS) produced from a 1:1 mixture of corn and wheat on visceral organ weight, intestinal morphology, and fasting whole-body oxygen consumption (FWBOC) were investigated in growing pigs in a 28-d trial. Twenty-four pigs (BW = 19.9 ± 0.5 kg) were individually housed in floor pens and randomly assigned to 3 experimental diets (8 pigs per diet). The diets contained corn and soybean meal with 0% (control) or 30% DDGS (DDGS diet); the third diet was supplemented with a multienzyme complex in addition to the 30% DDGS (DDGS + enzyme diet). All diets had similar nutrient concentrations and met the 1998 NRC nutrient requirements for growing pigs. Pigs were fed at 4% of their BW once daily. On d 15, 4 pigs from each dietary treatment were randomly selected for measurement of FWBOC during the 24- to 30-h postprandial period using an open-circuit indirect calorimeter. At the end of the study, pigs were killed to determine visceral organ weights, ileal and cecal digesta viscosity, and intestinal morphology. There was no effect (P > 0.05) of dietary treatment on final BW, WBFOC, or digesta viscosity. Empty BW of pigs fed the control diet was heavier (P = 0.02) than that of pigs fed the DDGS diet, but the empty BW of pigs fed the DDGS + enzyme diet was not different (P > 0.05) from that of pigs fed the control or DDGS diet. There were no differences (P > 0.05) in empty BW of liver, spleen, pancreas, heart, stomach, small intestine, and cecum among dietary treatments on a per kilogram basis. However, pigs fed the DDGS diet had heavier (P < 0.05) colon plus rectum and portal-drained viscera (PDV) than pigs fed the control diet, but weights of colon plus rectum and PDV in pigs fed the DDGS + enzyme diet were not different (P > 0.05) from those of pigs fed the control diet. Although morphological data showed no differences (P > 0.05) in the duodenum, jejunum, and colon segments among dietary treatments, the DDGS diet tended to decrease (P < 0.10) villous height and villous height to crypt depth in the ileum. The results of this experiment indicated that pigs fed a diet containing 30% DDGS have reduced dressing percentage and increased visceral organ mass compared with pigs fed a corn-soybean meal diet. However, the addition of a multienzyme complex to the DDGS diet resulted in pigs having a dressing percentage and visceral organ mass that are not different from those of pigs fed a corn-soybean meal diet.     

Responses to dietary additions of fiber (alfalfa meal) in growing pigs housed in a cold, warm or hot thermal environment

Five trials involving 112 individually-penned animals were conducted to determine the effects of dietary fiber additions (0 or 10% dehydrated alfalfa meal) on the rate and efficiency of growth and carcass characteristics of growing pigs housed in a cold (10 C), thermoneutral (22.5 C) or hot (35 C) thermal environment. Cold exposure (10 C) depressed efficiency of feed and energy utilization, carcass length, backfat, cold carcass dressing percentage and percentage lean cuts. Exposure to the hot environment resulted in depressed live weight gains but did not alter the efficiency of feed utilization. Dietary additions of alfalfa meal depressed daily gains by 1, 3 and 5% in pigs housed in the cold, warm and hot environments, respectively, and gain:feed ratios by 1, 7 and 10%. Ingestion of the fibrous alfalfa meal depressed cold carcass dressing percentage in the 10 and 22 C environments as compared with the basal diet. Based on these data, the nutritional value of fibrous feedstuffs (15% total dietary neutral detergent fiber or less) for growing pigs allowed to consume feed ad libitum is greater in animals housed in a moderately cold vs a warm or hot thermal environment.     

饲喂脆茎全株水稻对生长肥育猪生长性能、养分消化和胴体品质的影响

体重相近的杜洛克生长母猪54头，随机分成3组（每组3个重复），研究脆茎全株水稻（3个水平0、10％和20％）用于生长肥育猪日粮，对猪的生长性能、养分消化、胴体品质和肉质的影响。结果表明，生长猪阶段（29～52kg）对照组、10％组和20％组的采食量、平均日增重和料重比均无显著差异（P〉0．05）。肥育猪阶段（54～85kg）采食量和平均日增重，20％组显著低于对照组（P〈0．01），10％组与对照组之间无显著差异（P〉0．05）；各组料重比均无显著差异（P〉0．05）。生长猪阶段10％组和20％组各种养分的消化率都低于对照组；而肥育猪阶段，两组NDF消化率显著低于对照组（P〈0．01），其它养分消化率与对照组无显著差异。与对照组相比，10％组和20％组屠宰率有所下降，而瘦肉率提高，眼肌面积增大，背膘厚降低，但差异均不显著（P〉0．05）。10％组和20％组的背最长肌蛋白含量增加，脂肪含量降低，其中20％组与对照组差异显著（P〈0．05）；滴水损失和大理石纹及肉色评分各组之间均无显著差异（P〉0．05），20％组宰后24h的pH，显著高于对照组（P〈0．01）。     

Effect of carbohydrate source on growth performance, carcass traits, and meat quality of growing-finishing pigs

Two experiments were conducted to determine the effect of substituting a more available dietary carbohydrate (CHO) for portions of corn or fat in the diet on growth performance, carcass traits, meat quality, and serum or plasma metabolites in growing-finishing pigs. A three-phase feeding program was used with corn-soybean meal diets formulated to provide 105% of the Lys requirement for barrows or gilts gaining 325 g of lean daily in Exp. 1 or gilts gaining 350 g of lean daily in Exp. 2. Diets were isoenergetic within experiments. All other nutrients met or exceeded suggested requirements. In Exp. 1, pigs were allotted to three dietary treatments (0, 7.5, or 15.0% sucrose), with three replications of barrows and three replications of gilts, and with three or four pigs per replicate pen; average initial and final BW were 25.2 and 106.7 kg. In Exp. 2, gilts were allotted to two dietary treatments (waxy [high amylopectin] or nonwaxy [75% amylopectin and 25% amylose] corn as the grain source), with five replications of four gilts per replicate pen; average initial and final BW were 37.7 and 100.0 kg. In Exp. 1, ADG and gain:feed ratio increased linearly (P < 0.02) as dietary sucrose increased. Minolta color scores, a* and b*, and drip loss (P < 0.06) also increased linearly with added sucrose. In Exp. 2, ADG, carcass weight and length, and the Minolta a* value were greater for pigs fed waxy corn (P < 0.08) than for those fed nonwaxy corn. Feed intake, longissimus muscle area, 10th-rib and average backfat thickness, dressing percentage, fat-free lean, percentage of lean and muscling, lean gain per day, total fat, percentage fat, lean:fat ratio, serum or plasma metabolites (Exp. 1: serum urea N; Exp. 2: serum urea N, and plasma nonesterified fatty acids, triacylglycerols, total and high-density lipoprotein cholesterol, insulin, and total protein), pH of the longissimus muscle, and subjective muscle scores (color, firmness-wetness, and marbling) were not affected by diet in either experiment. In summary, increasing availability of dietary CHO in growing-finishing pig diets improved growth performance, but it did not affect carcass traits.     

Reduction of carcass fat in swine with dietary addition of dihydroxyacetone and pyruvate

Swine weighing 80 to 85 kg were fed a basal corn-soybean meal diet plus a mixture of dihydroxyacetone and pyruvate (3:1) (triose) or Polycose (control), a glucose polymer, as 3.85% of calories (4% of the diet). Twenty-four pigs were pair-fed the triose mixture or control diet for 28 d in litter-mate pairs of the same sex. Weight gain and feed consumption were recorded and carcasses were evaluated for fat and muscle accretion. The right rear leg and rear one-third of the right loin were skinned, deboned, ground and analyzed for protein, fat, moisture and ash content. Average backfat depth and backfat depth at the first, last and 10th rib were reduced by 12, 15, 14 and 12% (P less than .01), respectively, in triose-fed pigs. Loin eye area and untrimmed lean cuts were not altered by diet, but percentage trimmed lean cuts was higher (P less than .02) in triose-fed pigs (57.6 vs 55.3%). Leg and loin tissue samples from pigs fed the triose mixture had a lower (P less than .01) percentage of fat and a corresponding increased (P less than .01) percentage of protein. Organ weights and the blood biochemical profile were not altered by triose feeding. Liver function tests were not altered in animals consuming the trioses, except for an 18% decrease (P less than .05) in serum glutamic pyruvic transaminase. Ingestion of dihydroxyacetone and pyruvate will reduce body fat in limit-fed swine without reducing muscle protein deposition.     

Performance,carcass and technological meat quality of pigs in indoor and outdoor production systems

Abstract

This study aimed to compare different production systems, i.e., the combined effect of outdoor and indoor rearing of pigs and organic diets fed ad libitum or restrictively. Furthermore, the suitability of two breed crosses for outdoor rearing was studied. The effects on performance, carcass and technological quality traits were investigated. During two years, 240 pigs of Duroc x Large White (D*LW) and Swedish Landrace x Large White (L*LW) were allocated to three production systems: 1) Pigs kept outdoors, fed an organic diluted diet (20% alfalfa roughage) ad libitum; 2) Pigs kept outdoors, strategically fed a diluted organic diet up to a live weight of approximately 80 kg and thereafter an undiluted organic diet ad libitum; 3) Pigs kept indoors, fed an undiluted organic diet restrictively. For outdoor pigs, strategic feeding increased daily weight gain and backfat thickness, compared with feeding a diluted diet throughout (p≤0.01). L*LW pigs in both outdoor systems grew slower than in the indoor system (p≤0.001), whereas for D*LW pigs only outdoor pigs fed the diluted diet had a slower growth rate. Outdoor pigs had lower dressing percentage than indoor pigs. Glycogen content and L* values in M. longissimus dorsi were higher, whereas b* values were lower in meat from pigs in the indoor system. D*LW pigs had higher water-holding capacity (lower drip, thawing and cooking losses), lower shear force and higher intramuscular fat content compared with L*LW pigs.     

肥育猪饲粮中添加苜蓿草粉对其生产性能、消化率及血清指标的影响

本研究目的在于评价在玉米－豆粕型基础饲粮中添加苜蓿草粉对肥育猪的利用价值。选取体重约５０ｋｇ的杜×长×大三元杂交猪４０头,采用单因子完全随机设计,分为５个组,每组４个重复,分别在饲粮中添加不同比例的苜蓿草粉,依次为：０（对照组）,１０％（试验Ｉ组）,１５％（试验ＩＩ组）,２０％（试验ＩＩＩ组）,２０％＋０．１％纤维素酶（试验ＩＶ 组）,各组主要营养指标相同。测定肥育猪饲喂含不同水平苜蓿草粉饲粮后主要生产性能、消化率及血清中主要生化指标的变化。结果表明,１）试验ＩＩ、ＩＩＩ、ＩＶ 组平均日增重、采食量较对照组明显提高,而试验ＩＩ、ＩＶ 组的料肉比明显降低,因此,添加１５％的苜蓿草粉或２０％的苜蓿草粉＋０．１％ 纤维素酶有利于提高肥育猪的体重及饲料转化率。２）试验Ｉ、ＩＩ组和对照组相比,其干物质、粗蛋白质、粗灰分、中性洗涤纤维的表观消化率均不同程度提高;虽然试验ＩＩＩ、ＩＶ 组上述４项指标的表观消化率和对照组相近或稍高,但试验ＩＶ 组各主要指标优于试验ＩＩＩ组,说明添加１０％和１５％的苜蓿草粉有利于提高营养物质的表观消化率,苜蓿草粉添加至２０％时加纤维素酶对各项指标消化率有改进。３）肥育猪饲粮中添加苜蓿草粉,降低了其血液甘油三酯、胆固醇及低密度脂蛋白胆固醇含量,升高了高密度脂蛋白胆固醇含量。试验证明,在肥育猪饲粮中添加１５％紫花苜蓿草粉对肥育猪生产性能、营养物质消化率及血清生化指标的改善有利,苜蓿草粉降低血液胆固醇的功能可能是其中皂苷的作用。     

Effects of conjugated linoleic acid on the belly firmness and fatty acid composition of genetically lean pigs.

A study of the effects of conjugated linoleic acid (CLA) on the belly firmness and fatty acid composition of genetically lean pigs was conducted. From 75 to 120 kg live weight, 30 gilts were allowed ad libitum access to a corn-soybean meal diet supplemented with either 1% CLA oil (CLA-60) or 1% sunflower oil (SFO) or were fed the sunflower oil-supplemented diet restricted to the amount consumed by pigs fed the CLA-60 diet (RSFO). Conjugated linoleic acid oil consists of 60% positional and geometric isomers of CLA. Pigs fed SFO exhibited higher average daily gains (0.98 vs 0.80 kg/d, P < 0.01) than RSFO-fed pigs, but there were no effects of dietary treatment on feed intake or feed efficiency. Dietary treatment did not affect (P > 0.05) backfat thickness or longissimus muscle area. Bellies of gilts fed CLA-60 were subjectively evaluated to be firmer (2.91 vs 2.43 or 2.07 +/- 0.13, P < 0.01) than those of SFO- or RSFO-fed gilts, respectively. The longissimus muscle of gilts fed CLA-60 contained more saturated fatty acids (39.77 vs. 36.04 or 36.73 +/- 0.74%, P < 0.001) and less unsaturated fatty acids (60.23 vs 63.96 or 63.27 +/- 0.74%, P < 0.001) than that of gilts fed SFO or RSFO, respectively. The belly fat of gilts fed CLA-60 contained more saturated fatty acids (44.45 vs. 37.50 or 36.60 +/- 0.46%, P < 0.001) and less unsaturated fatty acids (54.78 vs. 61.75 or 62.47 +/- 0.46%, P < 0.001), resulting in lower iodine values (57.69 vs 66.37 or 65.62 +/- 0.91, P < 0.001) than that of gilts fed SFO or RSFO, respectively. Gilts fed CLA-60 accumulated more CLA in the longissimus muscle (0.55 vs 0.09 or 0.09 +/- 0.03%, P < 0.01) and belly fat (1.56 vs. 0.13 or 0.13 +/- 0.15%, P < 0.001) than did gilts fed SFO or RSFO, respectively. Dietary treatment did not affect (P > 0.05) 24-h pH, drip loss or subjective quality evaluations of the longissimus muscle. The effect of supplemental CLA to improve belly firmness is of practical significance and may provide a nutritional solution to carcass fat and belly firmness problems, thereby enhancing the overall value of extremely lean carcasses.     

妊娠母猪饲粮中不同苜蓿鲜草替代量对其生产性能的影响

在母猪妊娠期用不同比例的紫花苜蓿鲜草代替部分精料,研究其对生产性能及经济效益的影响。试验选用胎次、配种时间、上胎产仔数、体况等基本一致的大长二元母猪30头,采用单因子完全随机设计,共分为6个组,每组5头猪,每头猪1个重复。对照组饲喂基础日粮,试验Ⅰ、Ⅱ、Ⅲ、Ⅳ组分别用紫花苜蓿鲜草代替10%,20%,30%,40%的基础日粮(按干物质折算),试验Ⅴ组用紫花苜蓿草粉代替20%的基础日粮。结果表明:1)和对照组相比,在妊娠母猪饲粮中无论是用不同比例的紫花苜蓿鲜草还是用20%的苜蓿草粉代替精料,均提高了饲粮中粗蛋白质、粗灰分、中性洗涤纤维、酸性洗涤纤维、钙和总磷的表观消化率,其中试验Ⅲ组的提高幅度最大,极显著高于对照组(P＜0.01);随着紫花苜蓿鲜草替代量的增加,粗脂肪的表观消化率依次下降,但苜蓿草粉组和对照组几乎无差别。2)随着紫花苜蓿鲜草替代量的增加,繁殖期母猪体增重和背膘增加量均呈先升后降的趋势,而妊娠期母猪背膘增加量和泌乳期母猪背膘减少量依次下降。和对照组相比,在妊娠期母猪饲粮中以紫花苜蓿鲜草和草粉替代等干物质量的精料,均提高了母猪的采食量,其中试验Ⅲ组的采食量最大,极显著(P＜0.01)高于对照组。紫花苜蓿鲜草和草粉替代精料后,断奶至发情时间间隔有所缩短,但各组之间差异不显著(P＞0.05)。3)随着紫花苜蓿鲜草替代精料量的增加,提高了初生窝产仔猪总数、初生窝产活仔数、断奶仔猪数、断奶窝重和断奶窝平均日增重;鲜草试验组(试验Ⅲ组除外)的断奶仔猪个体重和对照组相似,试验Ⅴ组显著(P＜0.05)高于对照组和其余各试验组,试验Ⅴ组的断奶仔猪日增重也极显著(P＜0.01)高于对照组和其他试验组。综合分析认为,母猪妊娠期饲粮中用30%的紫花苜蓿鲜草代替精料其生产性能和经济效益最佳。     

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.     

Effects of modified tall oil versus a commercial source of conjugated linoleic acid and increasing levels of modified tall oil on growth performance and carcass characteristics of growing-finishing pigs

Two experiments were conducted to evaluate the effects of conjugated linoleic acid (CLA)-enriched feed additives for swine. These additives included a source of CLA that was commercially available (CLA-60) and modified tall oil (MTO). Experiment 1 used 36 barrows (initially 37.6+/-2.8 kg) to compare the effects of CLA-60 and MTO on growth performance and carcass characteristics of finishing pigs. The corn-soybean meal diets contained .50% soybean oil (control), .50% CLA-60, or .50% MTO. Pigs fed CLA-60 had less (P = .03) ADG from 37.6 to 72.6 kg than the control pigs; otherwise, pigs fed either CLA-60 or MTO had growth performance similar (P > .15) to that of the control pigs. Pigs fed MTO grew faster (P = .03) and consumed more feed (P = .10) over the duration of the experiment (37.6 to 106.4 kg) than pigs fed CLA-60. Dietary treatment did not affect (P > .15) plasma triglycerides or carcass characteristics, but pigs fed either MTO or CLA-60 had greater saturation of fatty acids in the adipose tissue at the 10th rib than pigs fed the control diet. Experiment 2 used 80 barrows (initially 33.4+/-2.2 kg) to examine the effects of increasing levels of MTO on growth performance and carcass characteristics of finishing pigs. The corn-soybean meal diet contained 1% cornstarch, which was replaced with MTO to give dietary levels of .25, .50, or 1.00% MTO. Dietary treatment did not affect (P > .15) growth performance. Feeding increasing levels of MTO quadratically decreased (P = .02) average backfat thickness and longissimus muscle drip loss (P = .04) and quadratically increased longissimus muscle area (P = .07) and percentage lean (P = .03). Feeding MTO tended to increase belly firmness (P < .10) compared with pigs fed the control diet. These traits appeared to be optimized with .50% MTO. In summary, pigs fed MTO had greater ADG, ADFI, and ending BW than pigs fed CLA-60. Feeding MTO does not appear to affect growth performance but improves carcass lean content and may additionally improve some aspects of meat quality in growing-finishing pigs.     

Survival and postweaning performance of pigs from sows fed fat during late gestation and lactation

Sows were fed a control corn-soybean meal gestation diet to d 80 of gestation. One group of sows (n = 25) continued receiving the control diet until the end of lactation, whereas two groups were placed on other treatments. One group (n = 27) was fed a diet containing 5% added solid fat pellets from gestation d 80 through lactation, whereas another group (n = 25) was fed a diet with 10% added solid fat pellet from gestation d 100 through d 14 of lactation. Feed supply was 2.27 kg/d during gestation and to appetite during lactation. Pigs from sows fed the control diet or 5% solid fat pellet diet were weaned with an age range of 22 to 28 d and immediately allotted in a 2 x 3 factorially designed 4-wk feeding trial. Pigs from these two sow groups were fed diets 1) without fat, 2) with 4.5% choice white grease or 3) with 5% solid fat pellet. Sow weight loss, backfat change and pig weights were not different at weaning among treatments. Survival rates of all pigs to 21 d averaged 90% with no significant differences between treatments. Pigs from fat-fed sows had more (P less than .05) glycogen per gram of liver, 41% more total liver glycogen and 16% more serum glucose at birth. Weanling pigs from fat-fed sows grew slower (P less than .05) than pigs from control sows. Supplemental fat during gestation increased liver glycogen of pigs, which should help survival, but the feeding of fat throughout lactation had a negative effect on ADG during a 4-wk postweaning period.