Computer simulation model of swine production systems: II. Modeling body composition and weight of female pigs, fetal development, milk production, and growth of suckling pigs

Theoretical concepts and relationships used to develop a deterministic computer simulation model of female pigs during their reproductive life are described. The model predicts, in a continuous form, body composition and weight of female pigs, fetal development, sow milk yield, and growth of suckling pigs according to genotype, diet, and management conditions. The model simulates growth of adult female pigs. Dietary nutrients are used first for maintenance and second for fetal growth or milk production. Any surplus is retained in the body. Energy and protein body reserves are mobilized when a nutrient deficit occurs during gestation or lactation. However, the rates of body protein and fat accretion as well as the fat/protein ratio are limited by boundaries, the values of which depend on the nutritional and physiological status of the pig. The model's ability to simulate sow body weight changes and composition, fetal growth, milk production, and suckling pig's growth is illustrated.     

Computer simulation model of swine production systems: I. Modeling the growth of young pigs

Theoretical concepts and relationships were used to develop a deterministic pig growth model. The model predicts, in a continuous form, growth and body composition of boars, barrows, and gilts according to genotype, diet, and management conditions. The model is aggregated at the whole-animal level with three main elements of body composition; total body DNA, total body protein mass (PT), and total body mass of lipids, with PT determining the secondary elements of ash and moisture. The primary factors regulating growth were associated with cellular hyperplasia and hypertrophy in agreement with the basic concepts described by Baldwin and Black (1979). Differential equations representing DNA accretion and protein synthesis and degradation were adapted from Oltjen et al. (1985). Normal pig protein growth was characterized from published data. Body PT was used to reflect several metabolic activities related to animal size and age, as in some prior models. Dietary energy and protein were used in sequence until requirements are satisfied, first for maintenance, then for protein growth, and finally for fat deposition. A comparison between experimental and simulated results illustrates that the model may simulate growth and body composition of young pigs adequately.     

Influence of dietary protein and recombinant porcine somatotropin administration in young pigs: II. Accretion rates of protein, collagen, and fat.

The present study was conducted to determine the effects of different dietary protein levels and recombinant porcine somatotropin (rpST) administration on deposition rates of protein, fat, water, ash, and collagen in pigs. Ten groups of six barrows (30 kg BW) were restrictively fed (80% of ad libitum) one of five diets containing 11, 15, 19, 23, or 27% CP. Diets were isoenergetic and all contained equivalent amounts of lysine. Thirty barrows were treated daily with rpST (100 micrograms/kg) by i.m. injection; remaining pigs were treated with diluent for 42 d. At all levels of dietary protein intake, carcass and empty body accretion rates of protein, water, and ash were greater in rpST-treated pigs than in respective controls. The magnitude of change elicited by rpST was lowest in pigs consuming 11% CP. Administration of rpST resulted in a 34% decrease in the accretion rate of fat; increasing protein intake resulted in a linear decrease in fat accretion in control and rpST-treated pigs. Accretion rates of protein, water, ash, and fat were increased in viscera of rpST-treated pigs compared with respective controls; rates of visceral protein and water accretion were increased as dietary protein was increased, whereas deposition of fat was decreased in control and rpST-treated pigs. Administration of rpST resulted in an overall 66% increase in the utilization efficiency of dietary protein for empty body protein deposition. Protein intake had minimal effect on the concentration of collagen in the carcass; however, rpST treatment increased concentrations of total and soluble collagen by 30 and 33%, respectively. Recombinant pST had little influence on collagen crosslinking or maturation. Deposition rate of carcass collagen was increased 63% in rpST-treated pigs compared with respective controls.     

Interactive effects of thermal environment and dietary lysine and fat levels on rate, efficiency, and composition of growth of weanling pigs.

Two trials involving 96 weanling pigs were conducted in which pigs were maintained in constant thermal environments of 20 degrees (cool) or 32 degrees C (hot) and self-fed fortified corn-soybean meal-whey diets that contained three amino acid regimens (.7, 1.0, or 1.3% lysine; approximately 13.6, 17.8, and 22.0% CP) without and with 5% added fat (choice white grease) for 42 d. The pigs were weaned between 28 and 32 d of age (8.07 +/- .58 kg) and penned in groups of two. Pigs in the cool environment consumed more (P < .01) feed and ME, gained more (P < .01) weight, and retained more (P < .01) body protein, fat, and water than those housed in the hot environment. As dietary lysine level increased, daily BW gain and body protein and water accretion increased linearly (P < .01) from d 0 to 21 and quadratically (P < .01) from d 21 to 42 in both environments. However, the magnitude of these responses was less (P < .05) in the cool than in the hot environment. Dietary fat addition decreased (P < .05) gain:ME ratios and body protein and water accretion from d 0 to 21 in both environments, but the magnitude of the reduction was greatest in pigs fed the low lysine diets in the hot environment. Based on these data, the growth response of weanling pigs to dietary lysine and fat levels is dependent on the thermal environment in which the animals are housed.     

Models to quantify excretion of dry matter,nitrogen, phosphorus and carbon in growing pigs fed regional diets

Modern pig production contributes to many environmental problems that relate to manure, especially in areas with highly intensive production systems and in regions like Asia where the regulative control is not effective. Therefore, the objective of this study was to use three different pig diets varying in dietary protein, fibre and fat as representative for Danish （DK）, Thai （TH） and Vietnamese （VN） pig production to develop and evaluate different approaches to predict/calculate excretion from growing pigs in comparison with the experimentally determined values. Nine female growing pigs were used in a digestibility and balance experiment. Excretion of dry matter （DM）, nitrogen （N）, phosphorus （P） and carbon （C） of the experimental diets were determined. Due to the highest dietary fibre content, VN had the lowest digestibility of N, P and C （73, 49, and 73%, respectively） compared with the DK and TH pig diets. From the known diet composition using standard table values on chemical and nutrient digestibly, high accuracy （bias） and low variation was found and the results could be used for prediction on chemical composition and excretion in faeces and urine in growing pigs. Calculation based on standard values regarding nutrient retention in the pig body as used in the Danish manure normative system （DMNS） showed likewise to be quite useful for quantifying the total excretion of N and P. Overall, the results demonstrate that simple models that require cheap and normally available information on dietary nutrients can give useful information on nutrient excretion in growing pigs.     

Models to quantify excretion of dry matter,nitrogen, phosphorus and carbon in growing pigs fed regional diets

Modern pig production contributes to many environmental problems that relate to manure, especially in areas with highly intensive production systems and in regions like Asia where the regulative control is not effective. Therefore, the objective of this study was to use three different pig diets varying in dietary protein, fibre and fat as representative for Danish (DK), Thai (TH) and Vietnamese (VN) pig production to develop and evaluate different approaches to predict/calculate excretion from growing pigs in comparison with the experimentally determined values.Nine female growing pigs were used in a digestibility and balance experiment. Excretion of dry matter (DM), nitrogen (N), phosphorus (P) and carbon (C) of the experimental diets were determined.Due to the highest dietary fibre content, VN had the lowest digestibility of N, P and C (73, 49, and 73%, respectively) compared with the DK and TH pig diets. From the known diet composition using standard table values on chemical and nutrient digestibly, high accuracy (bias) and low variation was found and the results could be used for prediction on chemical composition and excretion in faeces and urine in growing pigs. Calculation based on standard values regarding nutrient retention in the pig body as used in the Danish manure normative system (DMNS) showed likewise to be quite useful for quantifying the total excretion of N and P.Overall, the results demonstrate that simple models that require cheap and normally available information on dietary nutrients can give useful information on nutrient excretion in growing pigs.     

Effect of swine weaning age on body fat and lipogenic activity in liver and adipose tissue

Two experiments were conducted to evaluate the effects of weaning swine at 2 or 5 wk of age on postweaning performance and fat metabolism. In the first experiment, 52 pigs were weaned at 2 or 5 wk of age with body weights determined from birth to 8 wk. The early weaned group was fed a 20% protein corn-soybean meal-oat diet containing 25% dried whey from 2 to 5 wk while both groups were fed a 20% protein cereal grain-based diet from 5 to 8 wk of age. In a second experiment, a total of 90 pigs weaned at similar ages and fed the same diet sequences were killed at weekly intervals from 2 to 8 wk of age to evaluate body fat content and lipogenesis in liver and adipose tissue. Lipogenic capacity was measured by incorporation of acetate-1 14C into the total lipid fraction in liver slices and adipose tissue minces or by monitoring liver ATP citrate lyase activity. The results demonstrate that pigs weaned at 2 wk experience a slower postweaning growth rate with lower empty body weights than those either concurrently nursing the dam or weaned at 5 wk of age. Both groups had similar body weights from 6 to 8 wk of age. The body fat content of nursing pigs increased from 2 to 5 wk of age. Pigs weaned at 2 wk lost approximately 25% of their body fat the first week postweaning while later-weaned pigs did not lose body fat postweaning. Body fat composition of both groups was similar by 8 wk of age. Lipogenic activity was higher in liver than in adipose tissue from 2 to 5 wk of age and remained relatively constant throughout the trial. Adipose tissue lipogenic activity was lower in the nursing pig but increased dramatically at 5 wk in the early-weaned group and 7 wk of age in the late weaned group. These results suggest that weaning age can affect postweaning body fat composition and that adipose contributes a greater lipogenic capacity than liver tissue as the pig matures.     

Protein and fat utilization in lactating sows: II. Challenging behavior of a model of metabolism

The objective was to challenge the behavior of an existing mechanistic model of sow metabolism using data from a study that determined effects of fat and amino acid intakes on milk production, body and mammary composition in sows nursing 10 to 12 pigs. Sows were second through fourth parity; litter size was standardized at 12 pigs within 3 d of farrowing, and lactation was for 20 d. Diets were formulated and fed to provide three different amounts of protein intake and two different amounts of fat intake. Data were used to challenge the behavior of an existing mechanistic, deterministic, dynamic model for describing variation in milk production and changes in body composition. Nutrient intake and initial body weights and compositions were used as direct inputs into the model. The model could describe milk production within 1 SD of the mean on all rations. The model described body fat within 1 SD of observed values, but overestimated final body protein by approximately 30% (or between 1 and 2 SD). The model described the change in body fat and protein in response to 5% additional fat in the ration within 1 SD of observed (simulated - observed = -1.1 kg for protein and -0.7 for fat). The simulated response to dietary protein was within 1 SD (2.6 kg): simulated response from medium to high protein was 1.0 kg, observed 1.2; simulated response from medium to low was -0.7 kg, observed 0.3 kg. Thus, the model was not as accurate in describing the body protein response to a low-protein diet and overall, overestimated the retention of body protein. This model has utility for setting specific research hypotheses and may be amenable to use by nutritionists in a variety of applications. Further improvement in the ability of the model to describe metabolism and production of lactating sows is limited by a severe lack of data on metabolic interactions. Data on rates of muscle protein synthesis and proteolysis and interactions between amino acids, fatty acids, and glucose are needed to improve this and other models of sow production.     

Effects of gender and genotype on the response of growing pigs to exogenous administration of porcine growth hormone

Sixty crossbred pigs (Large White x Landrace) were used in a 2 x 2 x 2 factorial experiment to investigate the effects of gender (intact males vs females) and strain (A vs B) on the response to exogenous porcine growth hormone (pGH) administration (0 [excipient-treated] vs .1 mg pGH.kg live weight-1.d-1). All pigs had ad libitum access to their diet; pGH was administered daily from 60 to 90 kg live weight. All aspects of growth performance and body composition were affected to different degrees by gender and pGH. Strain A pigs had a higher capacity for protein accretion, superior growth performance and contained less fat in the eviscerated carcass and empty body compared with Strain B pigs. Within each strain, intact males ate more feed, had a higher rate of protein deposition and exhibited faster and leaner growth than females. Exogenous pGH administration increased average protein deposition and growth rate by 84 and 34%, respectively, and reduced average feed intake, fat deposition rate, feed:gain and carcass fat content by 14, 59, 37 and 33%, respectively. The magnitude of the changes in growth performance, tissue accretion rates and body composition elicited by pGH were independent of strain. However, within each strain the improvement in feed:gain and reduction in carcass fat measurements elicited by pGH were proportionately larger for females than for intact males.     

Effect of dietary L-carnitine on growth performance and body composition in nursery and growing-finishing pigs.

Two experiments were conducted to determine the effect of dietary L-carnitine on growth performance and carcass composition of nursery and growing-finishing pigs. In Exp. 1,216 weanling pigs (initially 4.9 kg and 19 to 23 d of age) were used in a 35-d growth trial. Pigs were blocked by weight in a randomized complete block design (six pigs per pen and six pens per treatment). Four barrows and four gilts were used to determine initial carcass composition. L-Carnitine replaced ground corn in the control diets to provide 250, 500, 750, 1,000, or 1,250 ppm. On d 35, three barrows and three gilts per treatment (one pig/block) were killed to provide carcass compositions. L-Carnitine had no effect (P > 0.10) on growth, percentages of carcass CP and lipid, or daily protein accretion. However, daily lipid accretion tended to decrease and then return to values similar to those for control pigs (quadratic P < 0.10) with increasing dietary L-carnitine. In Exp. 2, 96 crossbred pigs (initially 34.0 kg BW) were used to investigate the effect of increasing dietary L-carnitine in growing-finishing pigs. Pigs (48 barrows and 48 gilts) were blocked by weight and sex in a randomized complete block design (two pigs/pen and eight pens/treatment). Dietary L-carnitine replaced cornstarch in the control diet to provide 25, 50, 75, 100, and 125 ppm in grower (34 to 56.7 kg; 1.0% lysine) and finisher (56.7 to 103 kg; 0.80% lysine) diets. At 103 kg, one pig/pen was slaughtered, and standard carcass measurements were obtained. Dietary L-carnitine did not influence growth performance (P > 0.10). However, increasing dietary carnitine decreased average and tenth-rib back-fat (quadratic, P < 0.10 and 0.05), and increased percentage lean and daily CP accretion rate (quadratic, P < 0.05). Break point analysis projected the optimal dosage to be between 49 and 64 ppm of L-carnitine for these carcass traits. It is concluded that dietary carnitine fed during the nursery or growing-finishing phase had no effect on growth performance; however, feeding 49 to 64 ppm of L-carnitine during the growing-finishing phase increased CP accretion and decreased tenth-rib backfat.     

The effect of daily energy intake on growth rate and composition of weight gain in pigs

An experiment with 29 crossbred female growing pigs (Dutch Landrace × Dutch Yorkshire) was carried out to measure the effect of daily energy intake on growth rate, N retention (according to the balance method) and composition of the weight gain. The weight gain composition was analysed by slaughtering pigs at regular intervals between 25 and 110 kg live weight. Two levels of daily energy intake, at an adequate protein intake, were used, and pigs on both treatments were slaughtered at the same age.Differences in daily energy intake affected growth rate and composition of the weight gain. Restriction of the daily energy intake by 20% caused a 15% lower live weight gain and a 12% lower N retention. Carcass muscle growth was 8% lower and fatty tissue growth was lower by 28%. Growth of bone was unaffected. Chemical analysis of different parts of the body revealed that reducing the daily energy intake by 20% caused an 8% lower protein deposition and a 28% lower fat deposition in the total body. However, there were differences between different anatomical parts of the body.Efficiency of pig meat production is discussed in relation to the effects of energy supply on weight gain composition.     

Influences of dietary protein level,amino acid supplementation and environmental temperature on performance,body composition,organ weights and total heat production of growing pigs

The study was conducted to determine the effects of feeding a 16% CP diet, a 12% CP diet, or a 12% CP diet supplemented with crystalline Lys, Trp, and Thr (12% CP + AA diet) in a thermal-neutral (23 degrees C) or heat-stressed (33 degrees C) environment on various body and physiological measurements in growing pigs. Heat-stressed pigs were given a 15% lower daily feed allowance than thermal-neutral pigs to remove the confounding effect of feed intake caused by high temperature. No diet x temperature interaction was observed for any variables (P > 0.09) except for pig activity and pancreas weight. At 33 degrees C, pig activity and pancreas weight did not differ among dietary treatments (P > 0.05). In contrast, at 23 degrees C, pigs fed the 12% CP diet had greater activity than those fed the 16% CP diet or the 12% CP + AA diet (P < 0.05). Pancreas weight was greater for pigs fed the 12% CP + AA diet than those fed the 12% CP diet (P < 0.05) when maintained at 23 degrees C. Compared with 23 degrees C, the 33 degrees C temperature decreased pig activity, heat production, daily gain, feed efficiency, and affected the concentration and accretion of empty body protein and ash, as well as weights of heart, pancreas, stomach, and large intestine (P < 0.05). Pigs fed the 12% CP + AA diet attained similar levels of performance and rates of empty body water, protein, lipid, and ash deposition as pigs fed the 16% CP diet (P > 0.10). Pigs fed the 12% CP + AA diet had lower serum urea plus ammonia nitrogen concentrations (P < 0.01) and total heat production (P < 0.05) compared with those fed the 16% CP diet or the 12% CP diet. These results confirm that, with crystalline AA supplementation, growing pigs fed a 12% CP diet will perform similar to pigs fed a 16% CP diet. The data further indicate that lowering dietary CP and supplementing crystalline AA will decrease total heat production in growing pigs whether they are housed in a thermal-neutral or heat-stressed environment.     

Development of a model to describe the compositional growth and dietary lysine requirements of pigs fed ractopamine

The objective of this research was to use recent ractopamine research data to develop an updated mathematical model to describe the daily compositional growth of pigs fed ractopamine. Mean increases of 18.2, 23.1, and 25.0% for daily protein accretion were assumed for 5, 10, and 20 ppm of ractopamine for an overall gain of 40 kg of BW gain during the feeding period. The relative effect of ractopamine described the rapid increase and subsequent decrease in the effect of ractopamine as a function of BW gain or days on test and ractopamine concentration (RC, ppm). The reduction in ME intake produced by ractopamine was described as 0.036 x (RC/20)(0.7) multiplied by the ME intake for the first 20 kg of BW gain, and then increasing to 0.078 x (RC/20)(0.7) at 40 kg of BW gain feeding period. The ratio of fat-free muscle gain to protein accretion increased by 14 to 16% with the feeding of ractopamine, depending on the dietary lysine/essential AA levels. The ratio of carcass fat gain to empty body lipid gain was increased when lysine and essential AA requirements were met. Daily protein accretion and fat-free lean growth were described as functions of dietary lysine/essential AA intakes. The percentage of lysine in protein accretion increased with the feeding of ractopamine from 6.80 to 7.15%, depending on ractopamine concentration. Equations predicting carcass measurements, such as fat and longissimus muscle depths from carcass weight and composition, were modified to incorporate prediction biases produced by ractopamine. For the four concentrations of ractopamine (0, 5, 10, and 20 ppm, respectively) during a 78 to 110 kg of BW feeding period, the model predicted performance levels for ADG (1.03, 1.15, 1.16, and 1.16 kg/d), gain:feed (kg of ADG/kg of ADFI; 0.360, 0.401, 0.412, and 0.425), dressing percentage (75.1, 76.0, 76.3, and 76.4), percentage fat-free lean (48.7, 51.0, 51.5, and 52.2), longissimus muscle area (38.8,41.8,42.5, and 43.5 cm2), 10th-rib fat depth (22.1, 19.8, 19.3, and 18.7 mm), and fat-free lean gain (321, 446, 467, and 495 g/d), comparable to recent research data. The model allows the effect of ractopamine to be added to farm specific pig growth curves. It can be used to evaluate ways to optimize the use of ractopamine, including duration of ractopamine feeding, concentration of ractopamine, and dietary lysine concentration.     

Interaction of dietary protein content and exogenous porcine growth hormone administration on protein and lipid accretion rates in growing pigs

Sixty-six intact male pigs were used to investigate the relationships between exogenous porcine growth (pGH) administration (0, excipient-treated, and .09 mg recombinant pGH.kg-1.d-1) and dietary protein content (8.3, 11.4, 14.5, 17.6, 20.7 and 23.8%) on protein and lipid accretion rates over the live weight range of 30 to 60 kg. Feed intakes were restricted (1.84 kg.pig-1.d-1) and pGH was administered daily by i.m. injection. Rate of protein deposition increased with increasing dietary protein up to 17.6 and 20.7%, respectively, for control and pGH-treated pigs; both growth and protein deposition were enhanced by pGH on the four higher protein diets but remained unaffected by pGH administration to pigs given the two lowest protein diets. Plasma IGF-I concentration was elevated by pGH administration in pigs given the four higher protein diets but unaffected by pGH with the two lowest protein diets. Rate of fat deposition was depressed on all dietary protein treatments by pGH administration; carcass fat content of control and pGH-treated pigs declined with each increase in dietary protein up to 17.6 and 23.8%, respectively. The results demonstrate that pGH acts independently on protein and lipid metabolism.     

日粮蛋白质水平对乌金猪肝脏组织脂类代谢相关基因表达的影响

为探讨日粮蛋白质水平对乌金猪肝脏组织脂类代谢相关基因表达的影响,试验选取体重约15 kg的乌金猪54头,随机分为3组,每组18头,为低、中和高蛋白质组,其在15～30、30～60及60～100 kg生长阶段的蛋白质水平分别为14%、12%、10%,16%、14%、12%和18%、16%、14%。猪在体重为30、60和100 kg时屠宰,取其肝脏组织,Real-time PCR定量检测脂类代谢相关基因的表达水平。结果显示,在30、60和100 kg时,乌金猪肝脏组织中ACC、FAS、SREBP-1C基因的表达水平均随着蛋白质水平的升高而降低;CPT-Ⅰ和PPARα基因的表达水平则随着蛋白质水平的升高而升高。由此表明,日粮高蛋白质水平显著降低肝脏脂肪酸合成代谢基因(ACC、FAS和SREBP-1C)的表达(P<0.05),提高脂肪酸分解代谢基因(CPT-Ⅰ和PPARα)的表达水平(P<0.05);脂肪酸合成减少,且被氧化的量增加,两者共同作用导致用于合成甘油三酯(TG)的脂肪酸含量降低,从而减少了从肝脏组织被运输到各个组织的TG含量,使机体沉积TG的能力降低。     

太湖流域地方猪种遗传结构评估和体重体尺性状差异相关选择位点鉴定

旨在解析太湖流域地方猪品种内部遗传结构,鉴定梅山猪亚群间、二花脸群体间和米猪群体间体重体尺性状差异的候选基因。试验采集440头猪样本(代表太湖流域地方猪最全面血统)进行基因芯片分型,并使用该基因分型数据集进行多种群体遗传学分析,明确太湖流域地方猪品种内部的遗传结构,并鉴定梅山猪亚群间、以及二花脸和米猪群体间体重体尺性状差异的候选SNP位点和候选基因。结果显示:在太湖流域地方猪种内部,二花脸猪与米猪间的亲缘关系最接近,其遗传距离小于梅山猪两个亚群间的遗传距离,并且拥有最为一致的进化路线。太湖流域地方猪各品种及梅山猪品种内两个亚群间都达到高度分化水平,Fst值均大于0.25,ADMIXTURE分析表明,包括梅山猪两个亚群在内的8个群体的群体结构不完全一致,在K=8时,各自展现出完全不同的祖先血统组成。通过梅山猪亚群间Fst分析、以及米猪和二花脸猪间Fst分析,在猪1、3和6号等染色体上,共鉴定到24个位点在两个分析中都表现出受选择状态,并在这些位点上下游50 kb范围注释到20个基因,其中有8个基因被报道与体重体尺性状相关。此外,受选择位点形成的选择区域与多个猪体重体尺相关QTLs重叠。试...     

Effects of energy intake and body weight on physical and chemical body composition in growing entire male pigs

Two experiments were conducted to determine independent effects of BW and DE intake on body composition and the partitioning of retained body energy between lipid and protein in pigs with high lean tissue growth potentials and when energy intake limited whole-body protein deposition. In a preliminary N-balance experiment involving 20 entire male pigs at either 30 or 100 kg BW, it was established that whole-body protein deposition increased linearly (P < 0.05) with DE intake at both BW. These results indicate that DE intake controlled whole-body protein deposition and that these pigs did not achieve their maximum whole-body protein deposition when fed semi-ad libitum. In the main serial slaughter experiment, 56 pigs, with a BW of 15 kg, were assigned to one of four DE intake schemes and slaughtered at 40, 65, 90, or 115 kg BW. Within DE intake schemes, DE intake was increased linearly (P < 0.05) with BW, allowing for an assessment of effects of DE intake and slaughter BW on chemical and physical body composition (carcass, viscera, blood). Between 15 and 90 kg BW, average DE intake of 16.1, 20.9, 25.2, and 28.8 MJ/d supported average BW gains of 502, 731, 899, and 951 g/d, respectively. The proportion of whole-body protein present in the carcass increased with BW and decreased with DE intake (P < 0.05), whereas the distribution of whole-body lipid between carcass and viscera was not influenced by BW and DE intake. A mathematical relationship was developed to determine the relationship between DE intake at slaughter (MJ/d) and chemical body composition in these pigs: whole-body lipid-to-protein ratio = 1.236 - 0.056 x (DE intake) + 0.0013 x (DE intake)2, r2 = 0.71. The data suggests that absolute DE intake alone was an adequate predictor of chemical body composition in this population of entire male pigs over the BW and DE intake ranges that were evaluated, simplifying the characterization of this aspect of nutrition partitioning for growth in different pig populations.     

Study on Differences of UCP3 Gene Expression of Reciprocal Crosses F1 with Luchuan Pig and Duroc Pig

In order to breed high quality pig strain and improve the pork quality,the intramuscular fat content and the differences of UCP3 gene expression were studied in Luchuan pigs with Duroc reciprocal cross F1 and its parents Luchaun pigs.8 head of Luchuan pigs,Luchuan pigs with Duroc reciprocal cross F1 generation were respectively selected to analyze the correlation of UCP3 gene expression with intramuscular fat and eye muscle area.Expression of UCP3 mRNA in muscles of different pig breeds were measured by Real-time RT-PCR,and the eye muscle area and intramuscular fat content were measured too.The results indicated that the eye muscle area,intramuscular fat and the UCP3 gene expression were significantly different in the three groups of pigs (P<0.05).The crossbreds inherited the big body size of Duroc,and the high intramuscular fat content of Luchuan pig.The extremely significantly negative correlations were observed between UCP3 gene expression and the pig eye muscle area,the extremely significantly positive correlations were observed between UCP3 gene expression and intramuscular fat content.UCP3 gene should be the main candidate gene for fat trait research in pigs.     

陆川猪与杜洛克猪正反交F1代UCP3基因表达差异研究

为培育优质猪品系,提高猪肉品质,本试验探索了陆川猪与杜洛克猪正反交F1代及其亲本陆川猪肌内脂肪含量和UCP3基因表达差异。试验分别选取陆川猪、陆川猪与杜洛克猪正反交F1代各8头,采用实时荧光定量RT-PCR方法测定肌肉中UCP3基因mRNA在不同品种猪中的表达量,并测定眼肌面积和肌内脂肪含量,以分析UCP3基因的表达量与脂肪和眼肌面积的相关性。结果显示,3组猪在眼肌面积、肌内脂肪含量和UCP3基因mRNA表达量上均差异显著(P<0.05),且正反交F1代均遗传了杜洛克猪体型大、陆川猪肌内脂肪含量高的优势,UCP3基因的表达量与猪眼肌面积呈极显著负相关,与肌内脂肪含量呈极显著正相关。初步推断UCP3基因可作为影响猪脂肪性状的主效基因。