Estimation of body composition of neonatal pigs via deuterium oxide dilution: validation of technique

Five studies were conducted to determine 1) the time period required for the equilibration of deuterium oxide (D2O) in body water in neonatal pigs following the intravenous (iv), intramuscular (im) or intraperitoneal (ip) injection of D2O and 2) the accuracy and precision of estimating body water, protein, fat and ash in neonatal pigs from the body D2O pool space. Deuterium oxide administered by iv and im injection equilibrated with body water by 40 and 20 min postinjection, respectively. Body D2O space determined from individual samples of blood fluids drawn at 40, 80 or 120 min postinjection accurately reflected body water determined by desiccation. The difference between D2O pool space determined at 120 min postinjection and body water in 4-kg pigs injected iv averaged - .050 kg, and the magnitude of the difference was relatively constant (standard deviation [SD] = .121 kg). The D2O pool space determined from im injection overestimated body water slightly (.163 kg), but the precision of the estimate was good (SD = .019 kg). Deuterium oxide injected ip did not consistently equilibrate by 200 min postinjection, and the estimated D2O pool space was not indicative of body water. The 90% confidence limits for estimating body water, protein, fat and ash in 4-kg pigs as determined by im and iv injection of D2O were .020 and .092 kg, .014 and .021 kg, .030 and .043 kg and .007 and .047 kg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of physical training on skeletal muscle enzyme composition in pigs.

Running exercise in pigs results in an elevation of lactic acid in blood. This elevation in blood lactate does not occur in physically conditioned pigs. Activities of succinic dehydrogenase, fructose-l,6-diphosphate aldolase, lactate dehydrogenase and creatine Phosphokinase as well as the myoglobin content were determined in m. gastrocnemius from 6 ergometer-trained and 4 untrained pigs. The succinic dehydrogenase and myoglobin contents were significantly higher (P<0.01) in trained animals, whereas no changes were noted in the aldolase and creatine Phosphokinase contents. The lactate dehydrogenase showed somewhat reduced levels in the trained pigs. This was accompanied by an increased H/M subunit ratio. The results provide evidence for an increase in the maximal aerobic metabolism in trained pigs and that trained pigs to a higher extent can rely on an aerobic energy metabolism during running exercise.     

The effects of body composition on the pharmacokinetics of subcutaneously injected ivermectin and moxidectin in pigs

Macrocyclic lactones are characterized by their long persistence in animals because of their extensive distribution into fat. This study examined the influence of body condition on the disposition of ivermectin (IVM) and moxidectin (MXD) in blood and fat following subcutaneous (s.c.) drug administration. 'Fat' and 'thin' lines of pigs were established using two different diets. All animals were then injected with either MXD or IVM at 300 microg/kg and blood samples were taken at regular intervals until slaughter. Two IVM-treated animals from each diet group were slaughtered at either 3 days or 3 weeks posttreatment. Two MXD-treated animals from each diet group were slaughtered at 3 days, 3, 6 or 9 weeks after treatment. Samples of backfat were taken from all animals at slaughter. Fluorescence HPLC was used to determine the concentrations of MXD or IVM in the plasma and fat samples. The plasma IVM concentration peaked more rapidly in the thin IVM treated pigs compared with the fat pigs. The concentration of IVM in backfat was significantly lower in the thin animals slaughtered 3 weeks after treatment. The MXD plasma concentration peaked within the first hour in both the thin and fat groups, but from 12 h posttreatment there was a higher MXD concentration in the plasma of the fat pigs resulting in MXD being detectable in these pigs for 28 days compared with only 17 days in the thin pigs. Despite this difference in plasma persistence no differences were seen in the MXD concentration of backfat between fat and thin animals. Body condition influenced the kinetic disposition of IVM and MXD following s.c. drug administration with both drugs being less persistent in thin compared with fat animals.     

The effects of undernutrition of suckled pigs on subsequent growth and body composition after nutritional rehabilitation

The effect of nutritional restriction and rehabilitation imposed between 5 and 35 d and 35 and 166 d of age, respectively, on body and tissue growth were investigated in 96 Yorkshire pigs from 12 litters. One-half of the pigs were allowed to suckle continuously until weaning (fully fed, FF); the remainder were removed from the sow for 16 h of each 24 h period (1600 to 0800 h), during which time they received only water (restricted feeding, RF). All pigs were fed ad libitum from 35 d of age. Although significantly lower body and tissue (liver, kidney and gastrocnemius muscle) weights were observed in the RF pigs at 35 and 70 d of age, by 166 d, because of compensatory growth between 35 and 166 d, the difference in body and muscle weights between the two groups of pigs (RF and FF) was reduced to 5%, but the difference in kidney and liver weight remained as high as 15 and 9%, respectively. Total DNA, RNA and protein in the tissues examined were also lower in the RF pigs at 35 and 70 d of age, but increased after ad libitum feeding to more than 90% of the corresponding value in the FF pigs by the time they reached 166 d of age. The results of these measurements and the comparison of the protein: DNA ratios of the tissues indicated that growth retardation in the RF pigs was associated with reduced cell proliferation in liver and kidney and nuclear proliferation in muscle rather than any decrease in cell (or fiber) volume. Percentage of fat was lower while percentage of protein was higher (on a dry matter basis) in the RF pigs than in the FF pigs at 35 d of age. No significant difference in fat and protein content in the carcasses between the RF and FF pigs at 70 or 166 d of age or 90 kg body weight was noted. The carcass of intact males had more protein and less fat than that of females.     

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.     

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.     

Physiologic and body composition changes in feeder pigs under simulated marketing conditions

Two experiments were conducted to determine changes in body composition and various physiologic variables in feeder pigs under simulated marketing conditions. In the first experiment, pigs were assigned to 1 of 4 treatment groups for 48 hours: (1) no water and feed; (2) water ad libitum, no feed; (3) no water, feed ad libitum; or (4) water and feed ad libitum. During a 48-hour recovery period, all pigs were allowed feed and water ad libitum. Plasma triiodothyronine decreased (P less than 0.01) within the first 24 hours in groups-1 and -2 pigs, but increased (P less than 0.01) within the first 6 hours of the recovery period. The circadian rhythm of plasma cortisol was disrupted in groups-1 and -3 pigs and during recovery in group-1 pigs. Packed cell volume increased (P less than 0.05) in groups-1 and -3 pigs and returned to initial values within the first 24 hours of the recovery period. In the second experiment, body composition was estimated by the 40K technique for fat-free body mass, percentage of nitrogen, and percentage of fat. Body composition was determined before and after pigs were allotted to 1 of 2 groups for 48 hours: group-1 pigs were given feed and water ad libitum and group-2 pigs were not given feed and water. Group-1 pigs gained 2.2 kg of body weight (P less than 0.01), 0.6% fat (P less than 0.01), 0.7 kg of fat-free body mass, and 0.02% nitrogen (P greater than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Chemical composition of growing pigs and its relationship with body tissue composition assessed by X-ray-computed tomography

Ninety hybrid (mainly Large White × Landrace) pigs from 2 experimental replicates were used to study the potential use of computed tomography (CT) as a nondestructive technology for estimating the chemical body composition of growing pigs. Body tissue components (lean, fat, and bone) of 6 live pigs from each sex (boars, gilts, and barrows) were assessed by CT imaging before slaughter at approximately 30, 60, 90, 120, and 150 kg of BW. After slaughter, the empty body components were ground and frozen until analyzed for protein, lipid, ash, and moisture content. Several growth functions were evaluated and the allometric function (Y = aBW(b)), which was evaluated as log(10)chemical component weight = b(0) + b(1)log(10)BW, provided the best fit to the data. For each sex, the allometric coefficient (b(1)) for protein (0.92 to 0.99) was close to but less than 1; for ash (1.03 to 1.12), it was close to but greater than 1; for moisture (0.82 to 0.86), it was less than 1, and for lipid (1.61 to 1.71), it was greater than 1. Deposition rates (change in component weight per unit change in BW) for each chemical component were predicted using derivatives of the function. The mean deposition rates for protein and lipid were 0.141 and 0.286 kg/kg of BW gain, respectively. The deposition rate for protein was generally stable across different BW, whereas that for lipid increased as BW increased. In addition, linear, quadratic, exponential, and logistic functions were fitted to the data to study the relationship between the CT data and chemical components. The linear function was assessed to be the best equation, based on the Bayesian information criterion. The prediction equation for protein (kg) = -1.64 + 0.28 × CT lean (kg), and for lipid (kg) = -0.69 + 1.09 × CT fat (kg), had R(2) values of 0.924 and 0.987, respectively. Sex had no effect (P > 0.05) on the prediction of protein and lipid. The effect of BW was not significant (P > 0.05) for the prediction of lipid, but it was significant (P > 0 0.05) for the prediction of protein. However, the addition of BW to the base prediction equation for protein resulted in an increase of only 0.013 in the R(2) value. It was concluded from this study that CT scanning has great potential as a nondestructive technology for estimating the physical and chemical body composition of pigs. Additional research is required to validate the utility and accuracy of the prediction equations.     

Suppression of somatotroph function induced by growth hormone treatment in neonatal pigs

The effect of recombinant porcine growth hormone (pGH) treatment on pituitary function was evaluated in young pigs. Piglets received intraperitoneal recombinant pGH implants (0.5 mg/d sustained release) or vehicle implants beginning at 3 d of age. Ten piglets were sacrificed at 4 and 6 wk of age (five piglets/treatment group) for the collection of pituitary glands, blood, and liver tissue. Blood samples also were drawn at 3 and 12 d of age. Serum concentrations of GH, prolactin (PRL), thyroid-stimulating hormone (TSH), insulin-like growth factor-1 (IGF-1) and IGF-2 were evaluated. Levels of IGF-1 and IGF-2 mRNA were determined in liver samples. Treatment with GH increased circulating levels of GH and IGF-1 (P < 0.01), but not PRL, TSH, or IGF-2. Hepatic IGF-1, but not IGF-2, mRNA levels were increased by pGH (P < 0.001). Cultured pituitary cells from each animal were challenged with 0.1, 1, and 10 nM GH-releasing hormone (GHRH); 2 mM 8-Br-cAMP; or 100 nM phorbol myristate acetate. The release of GH from cultured pituitary cells was stimulated by all secretagogues (P < 0.001). The secretion of GH, but not PRL or TSH, in culture was inhibited by previous in vivo GH treatment (P < 0.001). Similarly, cellular GH, but not PRL or TSH, content was lower in the GH-implant group (P = 0.005). Cell cultures from 6-wk-old piglets secreted more GH, but not PRL or TSH, than cultures from 4-wk-old piglets (P < 0.05). Likewise, cellular GH, but not PRL or TSH, content was greatest in cultures from 6-wk-old animals (P = 0.002). Piglet growth was not affected by exogenous GH treatment (P = 0.67). These results demonstrate that exogenous pGH treatment selectively down-regulates somatotroph function in young pigs.     

The effect of diet on performance, digestibility, blood composition and intestinal microflora of weaned pigs

Good evaluation variables are needed to study postweaning lag in early weaned pigs. In this study, performance, digestibility, concentration of blood components and aerobic fecal microflora under different dietary regimens from weaning at 3 wk of age to 35 d of age are reported. Treatment 1 (T1) consisted of a corn-soybean meal starter diet. Pigs in treatment 2 (T2) received a steamed, rolled oat groats-casein starter diet. Pigs in treatment 1 and 2 were weaned at 3 wk of age while those in treatment 3 remained with the sow. Treatment 1 pigs had lower average daily gains for the 2-wk trial as compared with T2 pigs (P less than .05). Three of the four animals consuming the corn-soybean meal diet were observed to have diarrhea during the experiment as compared with an occasional loose stool from the pigs fed oats-casein. There were no significant differences in digestibility of dry matter, crude protein or ether extract among pigs in T1 and T2. Digestibilities of ash and crude fiber were higher (P less than .05) in T1 pigs, while there was an increase (P less than .05) in digestibility of N-free extract by pigs in T2. Serum protein, Na, CO2 and blood hematocrit were not significantly different among treatments. Blood chloride was higher, whereas glucose was lower for pigs in T1 and T2 than T3 (P less than .05). Blood urea N was higher for pigs in T1 as compared with pigs in T2 or T3. Potassium was higher (P less than .05) for pigs in T1 as compared with those in T2 or T3.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of maternal streptozotocin-diabetes on fetal growth, energy reserves and body composition of newborn pigs

Two doses of Streptozotocin (50 and 100 mg/kg body weight) were administered to two groups of pregnant gilts at d 80 of gestation to determine the influence of two levels of maternal diabetes on the gilts, their developing progenies and the body composition of the pigs. All the experimental animals received 1.82 kg of gestation diet/day throughout gestation. Serum glucose concentration increased to hyperglycemic levels in low-dose and high-dose groups; insulin concentrations decreased (P less than .01) in the high-dose, but not in the low-dose group (P greater than .05). Maternal free fatty acids (FFA) increased (P less than .05) in both treatment groups when compared with the control. However, birth weight of the litter and litter size were not affected. The liver weight increased (P less than .01) in the progeny of high-dose but not the low-dose group. Total liver DNA and RNA were not altered by the treatments, however; total liver protein and protein:DNA ratio increased (P less than .01) in the progeny of high-dose gilts. Pigs from high-dose and low-dose groups showed increases (P less than .01) in liver glycogen concentrations and percentage liver lipid. Body chemical composition data showed increases in percentage dry matter and percentage lipid (P less than .05 and P less than .01, respectively) in the progeny of high-dose but not in the low-dose group. It was concluded that streptozotocin administered to gestating gilts increased the maternal nutrient supply to the developing pigs, which resulted in higher energy status of the pigs at birth.     

The effect of short-term fasting on sleep in pigs

Trials were conducted with twelve piglets of the German Large White breed, intended for fattening. Their age was 56 +/- 2 days and their average weight was 21 +/- 3.7 kg. The piglets were studied for the effect of short fasting on the time and nature of sleep. After 18 hours of fasting (skipping the morning feeding), the piglets were fixed to obtain a combined record, including the electroencephalogram (EOG). This record was used for analyzing the time of waking and sleep, both the NREM stage and REM episodes. The same observations were performed in the piglets after feeding. The differences in the obtained data between the groups of animals were subjected to statistical evaluation. The fasting animals slept for about 15% of all the time under study and their sleep included short NREM periods interrupted by waking. No REM sleep was observed in the fasting piglets. After feeding the piglets slept significantly longer (p less than 0.01), more than half the period of study. Episodes of REM sleep occurred repeatedly in four animals. It is indicated by the results that fasting reduces the length of sleep and the nature of sleep.     

Effect of protein and lysine levels in the diet on body gain composition and energy utilization in growing pigs

Eight replicates of four Large White littermate female pigs were used to evaluate the effect of protein and lysine levels in the diet on the efficiency of protein and energy utilization. In each replicate, one pig was slaughtered at about 20 kg live weight and the others received three diets that contained (per Mcal digestible energy) 37.5 and 2.00 g (diet pl), 37.5 and 2.35 g (diet pL) or 45.0 and 2.35 g (diet PL) of digestible protein and lysine, respectively. Pigs were slaughtered after a 7-wk period. Tissue and chemical composition of the gain and energy and nitrogen gain were determined by using the comparative slaughter technique. Metabolizable energy (ME) intakes were similar in the treatments. Pigs fed the pl diet had a smaller body weight and muscle gain and retained less nitrogen and more lipids than pigs fed pL and PL diets. The decrease in the level of nonessential nitrogen in the diet (pL vs PL) did not affect body weight and muscle gain and the amount of nitrogen retained in muscle tissues. However, pigs given the PL diet had a higher total nitrogen retention and a lower fat deposition and exhibited a higher heat production. For each gram of additional protein catabolized for energy purposes (PL vs pL), heat production was increased by 1.8 kcal. The amount of lysine per unit of muscle gain (38 g/kg) or protein deposited (120 g/kg) was independent of protein and lysine levels in the diet. Estimates of energy (indirect calorimetry) and nitrogen (balance technique) retention were also obtained on the same animals; results were comparable with data obtained by direct measurements.