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1.
The lower critical temperature (Tcr) and thermoregulatory heat production below Tcr were studied in Norwegian Landrace (N), Finnish Landrace (F), Dutch Landrace (D), and Great Yorkshire (Y) barrows. Animals, weighing 26 kg at the start, were kept in groups for 18, 2-d periods in climate respiration chambers at environmental temperatures (Tenv) between 11 and 26 degrees C. Feeding level of animals in a group was 93 g.kg-.75.d-1 (2.5 times maintenance) and based on mean BW. Great Yorkshire pigs had a higher growth rate and a lower feed to gain ratio than Landrace pigs. Production characteristics of Landrace breeds were similar. The derived Tcr of the breeds was between 18.0 and 20.4 degrees C, the lower value associated with Y pigs and the higher value with F pigs. Thermoregulatory heat production was 6.4 to 11.9 kJ.kg-.75.d-1.degrees C-1 and did not differ between breeds. Radiant surface temperature (Trs) of pigs increased by .4C degrees (= bTrs) when Tenv was raised by 1.0 C degrees between 11 and 26 degrees C. In D pigs, bTrs was higher than in other pigs. Radiant surface temperature was related to backfat thickness; bTrs was increased with greater backfat thickness.  相似文献   

2.
Thirty-two mature dwarf goats weighing between 16 and 30 kg (22.7 +/- 3.7, SD) were used to study the effect of Trypanosoma vivax infection on rectal temperature (RT), feed intake (DMI), and metabolic rate. Sixteen of the goats were infected intravenously with 14 X 10(6) T. vivax each; the 16 others served as controls. Animals were fed at about 1.1 times maintenance. Heat production was measured from 1 wk preinfection to 6 wk postinfection. From data on successive 9-min periods, heat production was calculated per 24-h period and separately for 0700 to 2000 (day period) and for 2000 to 0700 (night period). Rectal temperature was measured twice weekly. Compared with controls, animals infected with T. vivax developed and maintained a 1 degree C higher RT and a higher metabolic rate. After the prepatent period of 5 to 7 d, during which RT remained normal, all infected goats had a period of about 7 d with constant high temperatures. After that initial episode, RT fluctuated. Heat production of infected animals was increased by 15.6 kcal.d-1.kg-.75, or about 16%. This increase in heat production was greater during the night (22 kcal.d-1.kg-.75) than during the day (14 kcal.d-1.kg-.75). After T. vivax infection, large differences in DMI among animals were apparent. In four animals, a clear relation between DMI and RT was noted, but in 12 animals no such relationship was apparent.  相似文献   

3.
Effects of exogenous administration of porcine recombinant somatotropin (rpST) on protein gain and metabolic rate were measured in three genotypes (castrated males) of pigs (Pietrain, Duroc and a crossbreed between Dutch Yorkshire and Dutch Landrace). Six pigs of each genotype were assigned at approximately 60 kg to receive pST doses of either 0 (C) or 14 mg (T) administered i.m. twice weekly over 10 wk. Pigs were housed in individual metabolism cages at a room temperature of 20 to 22 degrees C and received feed at 2.6 times maintenance. Protein gain (N x 6.25) was measured over the final 6 wk of the 10-wk test period. For 2 wk in the test period (wk 2 and wk 5), six pigs of each treatment x genotype group were placed in a large respiration chamber and energy balances (in protein and fat) and metabolic rate were measured. Rate of weight gain measured over the final 6 wk of the experimental period increased by 105 g/d (13%) with rpST administration (P less than .01). Daily protein gain over 6 wk was increased by 48 g/animal with application of rpST (P less than .001). There was a genotype x treatment interaction (P less than .01) for protein gain. Daily protein gain in Durocs with pST treatment was increased (39%) more than in crossbreds (31%). Daily fat gain was decreased by 42 g/animal (P less than .001) by T. Daily heat production with rpST was increased by 12 kcal/kg.75, which is comparable to a 12% increase in the maintenance energy requirement.  相似文献   

4.
Effects of recombinant porcine somatotropin (rpST) on growth, lean tissue growth, feed intake, feed conversion, lean tissue feed conversion, backfat thickness and lean percentage were examined in 96 growing pigs. The experiment used barrows and gilts from the genotypes Duroc, F1 (Dutch Yorkshire x Dutch Landrace) and Pietrain. Half the pigs received 14 mg rpST i.m. twice each week starting at 60 kg; others received a placebo. Pigs had ad libitum access to a diet containing 2,162 kcal net energy and 182 g crude protein per kilogram and were slaughtered at either 100 or 140 kg live weight. From 60 to 100 and from 100 to 140 kg, live weight responses to rpST averaged as follows: daily gain, +4.5 and +19.9%; feed intake, -4.4 and +3.5%; feed conversion, -8.4 and -13.9%; backfat thickness, -13.8 and -22.8%; lean percentage, +4.4 and +8.7%; lean tissue growth rate, +8.6 and +35.8%; and lean tissue feed conversion, -13.1 and -24.9%. No gender x rpST interaction was detected. However, a genotype x treatment interaction was significant for backfat thickness at both slaughter weights, showing a higher response to rpST in Duroc than in Pietrain and F1. Growth performance was improved more by rpST in F1 and Pietrain than in Duroc, especially at higher weights, but carcass traits were improved more by rpST in Duroc. The response to rpST in lean tissue growth rate from 60 to 100 kg was highest in fatter animals (Duroc, barrows), whereas from 100 to 140 kg, response in lean tissue growth rate to rpST was highest in leaner animals (Pietrain, F1, gilts).  相似文献   

5.
Four Hereford X Red Angus yearling steers were acclimated to each of the following environments; cold (3 C), thermoneutrality (TNZ; 20 C) and heat (35 C). Intake was equalized for all treatments at 4.9 X kg X head-1 X d-1 (2.9 Mcal metabolizable energy/kg). Heat production, respiration rate and rectal temperature were determined after 3- and (21-h later) 24-h exposures to thermoneutral and heat stress test-temperatures: 25, 30, 32.5, 35, 37.5 and 40 C. Thermoneutral heat production (kcal X kg-.75 X d-1), after 3- and 24-h exposures, was greater (P less than .05) for the cold-acclimated cattle (139.6 +/- 5.0 and 153.0 +/- 5.8) as compared with the TNZ-acclimated cattle (117.7 +/- 5.0 and 121.6 +/- 5.8). Heat production of the heat-acclimated cattle after 3- and 24-h exposures to thermoneutrality was 121.0 +/- 5.1 and 123.5 +/- 3.2 and was not different from the TNZ-acclimated cattle. Heat production of steers acclimated to different temperatures was variable during the 3- and 24-h exposures to test-temperatures ranging from 25 to 40 C. Heat production increased linearly in the TNZ-acclimated cattle (24-h exposure) and in the heat-acclimated cattle (3-h exposure) at the rate of 1.3 and 2.3 kcal X kg-75 X d-1 X C-1 increase in test-temperature, respectively. In the other four comparisons, analysis by regression indicated no significant change in heat production. Rectal temperature and respiration rate increased significantly in either a linear or quadratic manner in all treatment groups exposed to test-temperatures from 25 to 40 C.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

6.
Effects of recombinant porcine somatotropin (rpST) on growth, feed intake, feed conversion, back-fat thickness and lean percentage were examined in growing Meishan pigs. The experiment comprised 42 barrows of which 20 were administered 14 mg rpST twice a week i.m., starting at 40 kg, the others received a placebo. Pigs were fed ad libitum a diet containing 9.2 MJ net energy and 156 g crude protein kg−1 and were slaughtered at 90 kg liveweight. From 40 to 90 kg liveweight, rpST effects were: daily gain +17.9%; feed intake −5.1%; feed conversion −17.5%; backfat thickness −29.8%; lean percentage +16.0%. The effects of rpST in Meishan are much larger than in a similar experiment with leaner western pigs. Development of synthetic breeds with Meishan in combination with the use of rpST in cross-bred fattening pigs may be a way to economically exploit the high fertility of Meishan.  相似文献   

7.
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.  相似文献   

8.
The dose related effects of recombinant porcine somatotropin (rpST) on growth, carcass characteristics, muscle properties, and meat quality were investigated in lean Belgian Landrace finishing pigs. Ninety-six pigs (48 barrows and 48 gilts) were injected daily with either vehicle, 1.5, 3, or 6 mg of rpST from 60 to 97.5 kg live weight. Each treatment group consisted of six pens of four pigs each (two of each sex). Pigs were given ad libitum access to a high-protein (20.4% CP) cereal-based diet. Administration of rpST increased (P less than .05) growth rate (16.3 to 25.4%) and improved (P less than .05) feed efficiency (16.9 to 29.4%). Feed consumption was reduced (12%; P less than .05) only in the 6 mg of rpST group. Liver, kidney, and heart weights were increased (P less than .05) in the 3 and 6 mg of rpST groups. Although the Belgian Landrace pigs are bred for superior carcass quality, rpST further improved (P less than .05) carcass composition at all dose levels as evidenced by a reduction (10 to 50%) in a number of subcutaneous fat depth measurements, an increase (10 to 20%) in longissimus muscle area, and an improvement in the lean cut:fat cut ratio. Rate of pH decline in the gluteus and longissimus muscles was similar, but rapid, in all groups (pH after 30 min = 5.74 to 5.94); the ultimate (24 or 72 h) pH was .15 to .2 pH units higher (P less than .05) in the pigs that received the 3 and 6 mg of rpST doses.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
The influence of dietary protein and recombinant porcine somatotropin (rpST) administration on growth and body composition was investigated in barrows. Ten groups of six pigs starting at 30 kg were restrictively fed (approximately 80% of ad libitum) one of five diets containing 11, 15, 19, 23 or 27% protein. Diets contained skim milk (12%). Soybean meal diluted with cornstarch was used as the supplemental source of dietary protein. Diets were isocaloric (3.8 Mcal DE/kg) and all contained the same amount of lysine (18 to 20 g/kg). Thirty pigs were treated daily with rpST (100 micrograms/kg) by i.m. injection; the remaining pigs were treated with sterile diluent (control) for 42 d. Growth rate was greater in rpST-treated pigs at all levels of protein intake; however, the magnitude of the response to rpST treatment was lowest among pigs fed the diet containing 11% protein. Feed:gain ratio, backfat depth and carcass fat content were decreased in rpST-treated pigs compared to respective controls. Additionally, the concentration of carcass fat decreased concomitantly with an increase in dietary protein intake. Concentration of carcass protein increased linearly as dietary protein increased in control and rpST-treated pigs. In contrast, treatment with rpST was associated with an increased visceral mass; the concentration of protein and fat in the viscera was influenced by protein intake but not by rpST. These results, characterized by few treatment interactions, suggest that when energy intake is kept constant and appropriately fed pigs serve as controls, dietary protein and rpST influence growth and body composition by independent mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
A study was conducted with seven groups of five to six Holstein-Friesian male calves to evaluate the effect of feeding level during 6 to 14 d of age on energy metabolism of unadapted young calves. Calves were transported at 2 to 3 d of age to their new environment. At 6 d of age measurements of heat production (HP) and ME intake started and continued over a period of 8 d. Calves were fed below (four groups) or near (three groups) the maintenance requirement (19 or 30 g of milk replacer powder.kg-.75.d-1). In contrast to ME intake, HP decreased throughout the experimental period. This decrease was larger at the low than at the high feeding level (3.1 vs .9 kcal.kg-.75.d-2; P less than .001). The relationship between HP and ME intake was estimated as HP = 91 + .318 x ME intake (kilocalories.kilogram-.75.day-1). The decrease in HP, together with the constant ME intake with time, resulted in a time-dependent relationship between HP and ME intake. Estimated basal metabolic rate and efficiency of ME utilization below maintenance decreased with time, whereas the maintenance requirement remained virtually unchanged (134 kcal.kg-.75.d-1). The influence of feeding level on energy metabolism in young calves increased with time. For at least 12 d after transportation the energy metabolism of young calves had not reached steady-state levels.  相似文献   

11.
Twenty-eight barrows were used to investigate the effects of exogenous porcine growth hormone (pGH) administration (0 and 100 micrograms.kg-1.d-1) between 30 and 60 kg on the subsequent and overall performance and carcass composition of pigs grown to 90 kg. The pGH was administered by daily i.m. injection and all pigs were fed one diet. Control animals were pair-fed to the intake noted for pGH-treated pigs between 30 and 60 kg and all pigs were fed ad libitum from 60 to 90 kg. Pigs administered pGH had an improved rate (36%) and efficiency (28%) of gain and an improved protein accretion rate (46%) compared to excipient-treated pigs. Pigs previously treated with pGH continued to exhibit superior (P less than .01) rate and efficiency of gain, and the gain was associated with enhanced protein accretion during the quiescent (postinjection) period compared with excipient counterparts. Administration of pGH between 30 and 60 kg reduced carcass fat and increased carcass protein and water at 90 kg, although fat accretion rate was comparable to that of control pigs. Results indicate that, to varying degrees, the stimulatory effects of pGH on growth performance are sustained following cessation of hormone treatment.  相似文献   

12.
The objective of this study was to determine the effects of recombinant porcine somatotropin (rpST) treatment during the finishing phase on subsequent reproductive function in crossbred gilts. Forty gilts weighing 50 kg and housed in a swine finishing facility were randomly assigned to control or rpST treatment. Four control and four rpST-treated gilts were allotted per pen. Twenty rpST-treated gilts received 6 mg of rpST.gilt-1.d-1 in 1 ml of buffered carrier and 20 control gilts received 1 ml of buffered carrier.gilt-1.d-1. Injections were administered daily at 1400 in the extensor muscle of the neck. All gilts received an 18% CP diet containing 1.2% lysine. Treatment was terminated when the average weight in each pen reached 110 kg. Gilts treated with rpST gained more weight (P less than .05) than control gilts (59.8 +/- 1.0 vs 53.5 +/- 1.0 kg). Age at puberty was not different (rpST, 182.2 +/- 3.3; control 181.4 +/- 3.1 d). Prior treatment with rpST did not significantly affect length of estrus (rpST, 1.9 +/- .1; control, 1.8 +/- .1 d) or estrous cycle length (rpST, 20.6 +/- .4; control, 20.4 +/- .4 d). Ovulation rates at second estrus were similar for rpST gilts (15.1 +/- .5) and control gilts (14.4 +/- .5). More embryos (P = .10) were recovered on d 9 to 12 of gestation from rpST-treated gilts than from control gilts (13.1 +/- .9 vs 10.7 +/- .9).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
Thirty-six barrows were used in a 2 X 3 factorial treatment array to determine the effects of time of injection (0800 [AM] or 1800 [PM]) of recombinant porcine somatotropin (rpST) (0, 50, or 100 micrograms.kg BW.d-1 adjusted weekly) relative to time of feeding on growth performance, carcass composition, serum hormones and metabolites, and muscle RNA, DNA, and protein. Pigs were fed at 85% of ad libitum and allowed access to feed between 0800 and 1200. Treatments were initiated at 38 kg and continued until each pig consumed an average of 7.5 Mcal of DE/d. There was no significant effect of injection time for any measure of growth performance or composition of gain even though rpST treatment improved most criteria evaluated. Treatment with rpST increased ADG by 30%, improved feed:gain by 23%, reduced lipid accretion by 46%, increased protein accretion by 69%, and increased loin eye area (LEA) by 26%. Time of injection also had no effect on serum hormones or metabolites, except for nonesterified fatty acids (NEFA), which were 20% higher in the AM-injected animals. Treatment with rpST increased (P less than .05) RNA concentration (21%) and RNA/DNA (17%) in longissimus dorsi (LD) muscle. In semimembranosus (SM) muscle, however, rpST administration resulted in an increased (P less than .05) DNA concentration (10%) and a decreased DM content (4%). These results suggest that rpST influences growth differently in these two muscles. We conclude that time of rpST administration (AM vs PM) has no effect on its metabolic properties and, therefore, no effect on growth performance in the pig.  相似文献   

14.
Thirty-seven pigs with an initial live weight of 60 kg were used to investigate the effects of daily exogenous porcine somatotropin (pST) administration at two dose levels (0 and 100 micrograms.kg-1.d-1) for a 31-d period on muscle fiber characteristics and meat tenderness of boars, gilts and barrows. Excipient boars and gilts had more alpha W and fewer alpha R fibers than did those receiving pST. The percentage of muscle fiber type for barrows was not affected by pST treatment. The administration of pST resulted in an increase in muscle fiber size for all three fiber types in all three sexes, but these changes were of greater magnitude in barrows (31.8%) and gilts (27.8%) than in boars (9.3%). Somatotropin negated the intrinsic sex effect differences in fiber area of the pigs. There was no difference in tenderness among excipient boars, barrows and gilts; however, with the inclusion of pST, shear force decreased in boars and gilts and increased in barrows. A high proportion of the pST-treated pigs contained giant fibers in the longissimus muscle. Furthermore, a small proportion of the pST-treated pigs exhibited pale, soft, exudative muscle. Whether the giant fiber anomalies occurred through increased muscle activity or from fibers undergoing degenerative changes was not determined.  相似文献   

15.
Energy utilization and blood traits of ponies fed fat-supplemented diets   总被引：1，自引：0，他引：1  
The digestibility and heat production values for three fats of different origin were determined. Four pony geldings (225 kg) were used in a study consisting of four successive digestion trials utilizing a 4 X 4 Latin square design. The four dietary treatments were basal alone and supplemented with 15% corn oil, blended fat or inedible tallow. The blended fat was composed of a mixture of animal and vegetable fats. A 7-d preliminary period preceded a 7-d total fecal collection period for each trial. Heat production values were obtained by indirect calorimetry and calculated from oxygen consumption data. Fat supplementation increased (P less than .05) dietary metabolizable energy from a basal value of 3,224 kcal.kg intake-1.d-1 to a mean value of 3,984 kcal.kg intake-1.d-1 for the three fat diets. No difference in heat production was observed among the diets, averaging 2,883 kcal.kg intake-1.d-1. Fats increased (P less than .05) the energy balance (metabolizable energy-heat production) approximately 88% over the basal. Corn oil and blended fat produced the greatest energy balance of the fats. Utilization of energy in fats, calculated by difference, was not different, but tended to be highest in blended fat and lowest in the corn oil. Apparent fatty acid digestibility increased (P less than .05) with the addition of fat to the basal, partially due to the dilution of endogenous fecal fat, but digestion coefficients were not different (P greater than .40) among the high fat diets.  相似文献   

16.
Twelve crossbred sows were used in an energy balance study to estimate energetic efficiency of milk production from feed. Balances were made from 7 to 14 d and from 18 to 25 d of lactation. Two feeding levels were applied (high and low). The low level (L) was meant to supply energy slightly above maintenance, with energy needed for milk to be derived from body reserves. The high level (H) was meant to supply sufficient energy for maintenance and for milk production. The low-level animals received 2.5 to 2.6 kg of feed/d and the high level animals 4.8 to 6 kg/d. The loss of weight of sows during lactation depended more on feeding level than on stage of lactation. A high level of feeding to sows resulted in heavier piglets compared with the low feeding level (significant after 10 d). At 24 d of age piglets with the high-feeding-level sows weighed 7.5 kg and those with the low-level sows, 5.7 kg. At the high level, animals excreted 1,200 to 2,800 kcal more milk energy per day than the low-level animals. Energy for milk from feed was produced with an efficiency of 67 to 69% with a maintenance requirement of 112 to 125 kcal metabolizable energy (ME) X W-.75 X d-1. Efficiency of milk production from feed was calculated as 62% and the maintenance requirement was 68 kcal. In this calculation, milk was corrected toward zero energy balance. Another way of calculating this efficiency after correcting feed toward zero energy balance resulted in estimates of 68% for efficiency and of 88 kcal ME X W-.75 X d-1 for maintenance requirement. From these data it was derived that, for each piglet, the sow needed to receive .5 to .6 kg of extra feed (ME content 3,000 kcal/kg) per day to cover milk production. Level of metabolic rate for nursing piglets was estimated as 97 kcal ME X W-.75 X d-1 for maintenance and, in addition, .195 kcal/kcal extra of milk intake above maintenance.  相似文献   

17.
The effects of cimaterol, a beta agonist, on basal metabolic rate, heat increment, maintenance requirements and carcass characteristics were determined using six treated and six control Suffolk ewe lambs. The lambs were fed a pelleted diet (18.7% CP, 2.64 Mcal ME/kg) with or without .5 mg cimaterol/kg BW.75 daily for 70 d. Heat production was monitored for 2 d on each animal at three levels of intake by respiration calorimetry. A 7-d total collection digestion trial was conducted on each animal at both high and low levels of intake. Cimaterol-fed lambs gained more (P less than .05) weight (174 vs 107 g/d) and had a higher (P less than .01) gain/feed ratio (151 vs 90 g/kg) than controls. Cimaterol did not affect diet digestibility or methane production. It reduced (P less than .01) urinary N excretion by 12% and improved (P less than .001) N retention by 18%. Cimaterol also increased carcass weight (26.9 vs 22.1 kg), dressing percentage (57.2 vs 53.9), longissimus muscle area (22.5 vs 15.0 cm2) and leg score (14.3 vs 12.2). Heat production was, on the average, elevated 7 to 10% on d 1 to 4 of cimaterol feeding but reverted to control levels by d 10. Cimaterol did not have any long-term thermogenic effects, either expressed as partial efficiency of ME use for growth (.48 vs .49), as maintenance ME requirements (76 vs 75 kcal/kg BW.75) or as fasting heat production (84 vs 80 kcal/kg BW.75) for treated vs control lambs, respectively. Results indicate little long-term thermogenic effect of cimaterol, even though growth rate and protein deposition were increased.  相似文献   

18.
Thirty-two pigs weighing approximately 50 kg were maintained in respiration chambers to measure their heat production and the partition of energy retention between protein and fat deposition at two environmental temperatures (23 and 13 C) and with two energy levels in the diet: 3.39 (HE) and 2.92 (LE) Mcal ME/kg. From energy balance data, maintenance requirements (MEm) and the efficiency (k) of energy (ME) utilization for energy deposition were calculated for each treatment. For both diets, MEm averaged 122 kcal ME/kg.75 at 23 C, the rate of increase of MEm being 3.7 kcal ME/kg.75 for each 1 C decrease in the environmental temperature. At 23 C, k was higher with the HE diet (.81 vs .55) and similar for both diets (.78) at 13 C. At comparable ME intakes, heat production was higher with the LE diet at 23 C, and the rate of increase of heat production between 23 and 13 C was lower with the LE diet (1 kcal/kg.75) than with the HE diet (3 kcal/kg.75), resulting in similar heat production at 13 C for both diets. This resulted in an interaction (P less than .01) between temperature and diet on heat production. Protein retention was lower (P less than .01) at 13 C but unaffected by diet at both temperatures. This resulted in an interaction (P less than .01) between temperature and diet on fat retention. Consequently, energy of LE and HE diets was similarly utilized at 13 C, while at 23 C, the HE diet was better utilized. The comparison between these results and those obtained in growth experiments is discussed.  相似文献   

19.
Three litters of four pigs from each of four different groups were used to evaluate the effect of porcine somatotropin (pST) on growth performance, body gain composition, energy and N metabolism, and in vitro cytochrome oxydase (final enzyme of the respiratory chain) activity of tissues. The four groups included boars from a synthetic line (SG1) or the Large White breed (SG2) and barrows from the Large White breed (SG3) or crossbred between Large White and Meishan breeds (SG4). Inherent capacity for daily lean tissue growth (LTG) decreased from SG1 to SG4. Within a litter, one pig was slaughtered and dissected at the beginning of the experiment (55 kg BW) and the three others were fed the same daily supply of protein and amino acids (26 g of lysine/d) but relative daily energy levels were either 113 (without pST: E1/0), 100 (3 mg of pST/d: E2/pST) or 87 (3 mg of pST/d: E3/pST). The 100 energy level corresponded to the ad libitum intake of E2/pST pigs. Two energy and N balances were carried out in respiration chambers during the experimental period. Pigs were slaughtered and dissected at approximately 95 kg BW and composition of gain was estimated using the comparative slaughter technique. In E1/0 pigs, daily BW, lean, and N gain were affected (P less than .01) by group; 566, 471, 374, and 315 g/d of lean tissue gain in SG1, SG2, SG3, and SG4 pigs, respectively. At high ME intake (E2/pST vs E1/0), pST increased daily BW (+14%), lean (+27%), or N (+26%) gain and reduced adipose tissue (-50%) gain, but the pST effect was inversely related to LTG: for N, the improvement was 2.8, 7.1, 7.0, and 11.1 g/d in SG1, SG2, SG3, and SG4 groups, respectively. Energy restriction (E3/pST vs E2/pST) reduced (P less than .001) adipose tissue gain in all groups but did not affect lean tissue or N gains in SG1, SG2, and SG3 pigs. In the pST-treated pigs of the SG4 group, the lean tissue or N gains were reduced (P less than .01) by energy restriction. Energy restriction combined with pST treatment (E3/pST) led to negligible amounts of fat deposited (40 g/d for SG1 + SG2 + SG3 pigs) and a gain:feed ratio higher than 500 g/kg (580 in SG1 pigs). The increased heat production measured in pST-treated pigs was due to its maintenance component: 275 vs 257 kcal of ME.kg BW-.60.d-1 (P less than .01).(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   

20.
Forty-five pigs with an average initial live weight of 60 kg were used to investigate the effects of daily exogenous porcine pituitary growth hormone administration at two dose levels (pGH; 0, excipient buffer injected, and 100 micrograms.kg-1.d-1) for a 31-d period on the performance and body composition of boars, gilts and barrows allowed to consume feed ad libitum. Excipient boars consumed less feed, exhibited faster and more efficient growth (P less than .01) and produced less fat and more protein and water (P less than .01) in the empty body compared with excipient barrows, which in turn contained more fat and less water (P less than .05) in the empty body than did excipient gilts. These differences were largely eliminated by pGH administration, which induced differential effects in growth performance and body composition in boars, gilts and barrows. Growth hormone administration improved growth rate by 13, 22 and 16% and feed conversion efficiency by 19, 34 and 32% in boars, gilts and barrows, respectively. The reduction of body fat content (g/kg) elicited by pGH was 22, 36 and 33% for boars, gilts and barrows, respectively, with a corresponding increase (P less than .01) of body protein and water content. The magnitude of the pGH responses was greatest for gilts and barrows compared with boars, negating intrinsic sex-effect differences in growth performance and body composition of pigs. Pigs used in this study and treated with pGH exhibited a rate of protein deposition (approximately 225 g/d) far greater than previously reported, and as such redefine the genetic capacity for lean tissue growth by the pig.  相似文献   

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