Growth performance, diet apparent digestibility, and plasma metabolite concentrations of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding level

Two experiments, each with 36 barrows with high-lean-gain potential, were conducted to evaluate apparent nutrient digestibilities and performance and plasma metabolites of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets. The low-protein diets were supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis or by feeding 90 or 80% of ad libitum intake. Pigs were fed for 55 d. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis or by feeding 80% of the ad libitum intake. Pigs were fed for 27 d. Pigs fed the CONTROL diet had greater (P < 0.05) ADG and feed efficiency (G/F) than pigs fed the IDEAL (Exp. 1 and 2) and AACON diets (Exp. 2). As the level of feed intake decreased, ADG decreased (P < 0.05), but G/F tended to improve (P < 0.10) for pigs fed 90% of ad libitum in Exp. 1 and for pigs fed 80% of ad libitum in Exp. 2. In Exp. 1, the apparent total tract digestibilities of DM and energy were greater (P < 0.01) for pigs fed the IDEAL diet than for pigs fed the CONTROL diet. In Exp. 2, the apparent total tract digestibility of protein was greatest in pigs fed the CONTROL diet (P < 0.05) and was greater (P < 0.05) in pigs fed the AACON diet than in pigs fed the IDEAL diet. Plasma urea concentrations were lower in pigs fed the IDEAL diet than in pigs fed the CONTROL diet, regardless of feeding level. For pigs fed the CONTROL diet, plasma urea concentrations were lower when feed intake was 80% of ad libitum (diet level, P < 0.01). In summary, pigs fed the IDEAL and the AACON diets gained less and had lower plasma urea concentrations than pigs fed the CONTROL diet. Based on these data, it seems that the growth potential of pigs fed the IDEAL and AACON diets may have been limited by a deficiency of lysine, threonine, and(or) tryptophan and that the amino acid pattern(s) used was not ideal for these pigs.     

Effect of colostrum intake on plasma glucose, non-esterified fatty acid and glucoregulatory hormone patterns in the neonatal pig

The effect of colostrum on endocrine and metabolic factors affecting glucose homeostasis was evaluated in 60 neonatal pigs that were fasted, fed (nursed ad libitum) or limit-fed colostrum (25% ad libitum, 4-hr interval feeding). Plasma acquired at birth (t0), and after 10, 20 and 30 hr (t10, t20 and t30, respectively) was analyzed for glucose, non-esterified fatty acids (NEFA), and the glucoregulatory hormones--insulin, glucagon, cortisol, growth hormone and catecholamines. The concentration of glucose and NEFA was similar among treatment groups at birth and increased in proportion to the quantity of colostrum consumed. Pigs fed ad libitum achieved and maintained a higher (greater than or equal to 40%; P less than .01) glucose concentration when compared to fasted neonates. Limit-fed counterparts also achieved and maintained higher levels, with glucose concentration being approximately 20% higher throughout (P less than .05). Fed pigs maintained NEFA concentrations which were approximately 2.5-fold to 4-fold greater than that of fasted pigs (P less than .05). Likewise, limit-fed pigs tended (P = .19) to have elevated NEFA concentrations and a lower (P less than .05) insulin:glucagon molar ratio. An inverse relationship was observed between colostrum intake and plasma concentrations of cortisol and growth hormone. Concentrations of epinephrine and norepinephrine tended (P greater than .10) to be elevated in fed pigs, relative to those of fasted counterparts. Provision of even limited quantities of colostrum is therefore beneficial to the glucoregulatory response in newborn pigs.     

Body composition and tissue accretion rates of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding levels

Two experiments, each with 39 high-lean-gain potential barrows, were conducted to evaluate the organ weights, body chemical composition, and tissue accretion rates of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2, and pigs were fed for 55 and 27 d in Exp. 1 and 2, respectively. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis, or by feeding 90 or 80% of ad libitum intake. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis, or by feeding 80% of the ad libitum intake. Three pigs were killed at the start of the experiments and three from each treatment were killed at the end of each experiment to determine body chemical composition. In both trials, the whole-body protein concentration (g/kg) and the accretion rates of protein (g/d) were greater (P < 0.05) for pigs fed the CONTROL than for pigs fed the IDEAL and AACON diets. In Exp. 1, pigs fed the CONTROL diet had a trend (P < 0.10) for greater water and lower lipid concentration and had greater (P < 0.05) water and ash accretion rates. Whole-body protein concentration was greatest (P < 0.05) in pigs fed at 80% of ad libitum, but protein, water, and ash accretion rates were greatest (P < 0.05) in pigs allowed ad libitum access to feed. In summary, pigs fed the IDEAL and the AACON diets had less protein in the body and lower protein accretion rates than pigs fed the CONTROL diet. It seems that reductions in protein deposition in pigs fed the IDEAL and AACON diets may have been due to a deficiency of one or more essential amino acids or possibly to increases in the NE for metabolic processes leading to increases in adipose tissue deposition.     

Enhanced Plasma Availability of the Metabolites of Albendazole in Fasted Adult Sheep

Lifschitz, A., Virkel G., Mastromarino, M. and Lanusse C., 1997. Enhanced plasma availability of the metabolites of albendazole in fasted adult sheep. Veterinary Research Communications, 21 (3), 201-211The influence of fasting prior to treatment and of dosing rate on the plasma availability and disposition kinetics of albendazole (ABZ) and its sulphoxide (ABZSO) and sulphone (ABZSO2) metabolites was studied in adult sheep grazing on pasture. A micronized suspension of ABZ was administered orally at either 7.5 mg/kg (group A) or 11.3 mg/kg (group C) to sheep fed ad libitum, and at 7.5 mg/kg to sheep subjected to a 24 h fasting period prior to treatment (group B). Blood samples were taken serially over 96 h after treatment, and the plasma was analysed for ABZ and its metabolites by high-performance liquid chromatography. ABZSO and ABZSO2 were recovered from the plasma. Fasting induced marked modifications in the pharmacokinetic behaviour of the ABZ metabolites in sheep. An extended absorption process, with a delayed peak concentration in the plasma, was observed for both metabolites in the fasted sheep. Significantly higher area under the curve (AUC) and peak plasma concentration (Cmax) values were obtained for both metabolites in the fasted animals compared to those fed ad libitum. Delayed elimination with prolonged detection in plasma was also observed in the fasted sheep. Treatment with ABZ at 7.5 mg/kg in the starved animals resulted in bioequivalence to the administration of the compound at a 50% higher dose rate (11.3 mg/kg) in the fed animals. It is suggested that fasting enhances ABZ dissolution and absorption by delaying its passage down the digestive tract.     

Conceptus and maternal responses to increased feed intake during early gestation in pigs

Maternal diet influences fetal growth and postnatal development. We hypothesized that conceptuses gestated in sows provided ad libitum vs. restricted feed intake would differ in the milieu of hormones, growth factors, nutrients, and metabolites associated with growth and metabolism. This hypothesis was tested in two experiments by providing fourth-parity sows (Pig Improvement Co. C15 bred to Line 326 boars) with either 1.81 kg/d (as-fed basis; control) or ad libitum access to gestation diet. In Exp. 1, control (n = 6) or ad libitum (6.4 +/- 0.11 kg/d; n = 9) treatments were provided from d 29 to 45 (onset of estrus is d 0), and sows were slaughtered on d 46. Ad libitum sows gained more weight from d 29 to 45 than controls (34.0 vs. 4.32 kg, respectively; P < 0.01). No differences were observed on d 46 for the number of fetuses, conceptus attachment length, allantoic + amniotic fluid volume, placental weight, fetal weight, and fetal crown-to-rump length. Variation in fetal crown-to-rump length was less (P < 0.03) in sows fed ad libitum. Sows fed ad libitum had greater (P < 0.01) IGF-I and insulin concentrations in plasma than controls on d 43. In Exp. 2, sows were fed 1.81 kg/d (n = 6) or ad libitum (7.0 +/- 0.11 kg/d; n = 4) from d 30 to 56 of gestation, when sows were anesthetized and samples were collected surgically from their gravid uteri. Sows fed ad libitum gained more weight (P < 0.01) than did controls and had more (P < 0.06) IGF-I in their plasma and the plasma collected from umbilical veins of their fetuses. No differences were found for concentrations of insulin or glucose in plasma of sows or fetuses, but urea N concentrations were greater (P < 0.05) in maternal plasma and in the plasma, and allantoic and amniotic fluids of conceptuses from sows fed ad libitum. Combined data from Exp. 1 and 2 revealed a treatment x fetal number interaction (P < 0.05) for average fetal weight. The expected negative relationship between within-litter average fetal weight and the number of fetuses per uterus was observed for control sows (y = 115.4 -1.75 x fetal number; P < 0.05), but litters of ad libitum sows did not show this effect. The hypothesis that providing feed in excess of established requirements in early gestation affects the in utero milieu is supported by these results. Data further reveal that, at least at mid-gestation, the restraint to fetal growth that is exhibited when fetal number increases in control sows is not exhibited when sows are fed ad libitum.     

Influence of level of dietary protein or energy on effects of ractopamine in finishing swine.

The effect of ractopamine, a beta-adrenergic agonist, on growth, nutrient utilization, and carcass composition was studied in pigs fed either 18% CP, 12% CP, or 18% CP restricted (RES = 67% of ad libitum) diets. The 18 and 12% CP diets provided 3.52 and 3.68 Mcal of DE/kg, respectively. All pigs were fed a low-protein (12% CP) diet during pretreatment growth from 15 to 60 kg. Ractopamine at 20 or 30 ppm (30 ppm for RES pigs) in the diet was fed from 60 kg live BW until slaughter at 105 kg (9 pigs/treatment). No ractopamine treatment effect (P greater than .05) was observed for either daily gain or gain/feed, although gain/feed was improved by 8% in both of the ad libitum groups. Ractopamine treatment resulted (P less than .01) in an overall reduction of carcass lipid by 8%, an increase of carcass protein by 5%, and a 21% improvement in the efficiency of protein utilization; the greatest changes occurred in the pigs fed the 12% CP diet (-17%, +11%, and +32%, respectively). The ad libitum daily feed intake was 15% less for pigs fed the 12% CP diet than for those fed the 18% CP diet (P less than .01), and there was a 10% reduction in intake of both diets with the addition of ractopamine (P less than .05). Both carcass lipid and protein deposition seemed to be closely related to energy intake (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of meal intervals and weaning on feed intake of early weaned pigs

Feed intake was investigated in early weaned pigs housed in two environments. In the first experiment, pigs in an unfamiliar environment (removed from the sow and placed in nursery pens) were offered a dry diet either ad libitum or at different meal intervals (2, 4 and 6 h). Regardless of meal interval (ad libitum or hourly intervals), early weaned (21 d) pigs failed to consume sufficient feed for maintenance during the first 3 d postweaning. Pigs provided feed ad libitum consumed more (P less than .001) feed (142 vs 84 g/d) and gained more (P less than .05) weight (57 vs 3 g/d) than meal-fed pigs over the 7-d period. Pigs fed at 2-h intervals consumed more (P less than .001) feed than pigs fed at 4-h or 6-h intervals. Compared with preweaning levels (307 mu eq/liter), plasma free fatty acid (FFA) levels increased approximately fourfold by d 1 postweaning (1,372 mu eq/liter), then decreased through d 7 to levels below preweaning (142 mu eq/liter). The FFA levels were not affected (P greater than .1) by meal interval. In a second experiment, feed intake was investigated in weaned pigs that were allowed to consume food by a familiar method and in a familiar environment (suckling the sow). When allowed to nurse following a 24-h weaning period, weaned pigs consumed (24.3 +/- 2.8 g/suckling) the same amount (P greater than .1) as non-weaned littermates (28.7 +/- 1.8 g/suckling).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of colostrum intake on hepatic gluconeogenesis and fatty acid oxidation in the neonatal pig

A total of 24 newborn pigs were used to determine 1) the relationship between the quantity of colostrum consumed and the capacity for gluconeogenesis and fatty acid oxidation and 2) whether fatty acid oxidation limits gluconeogenesis in isolated hepatocytes. Neonatal pigs were obtained prior to nursing and allotted to one of three treatment groups; fed (ad libitum), limit-fed (25% of fed group), or fasted. Hepatocytes were isolated when pigs were 24 h old. Colostrum intake altered the metabolic status of neonates such that the capacity for glucose synthesis and oxidation of octanoate increased with intake. Glucose synthesis with lactate as the substrate was greater (P less than .01) for fed pigs (10.79 mumol glucose.h-1.mg DNA-1) than for either limit-fed (6.56) or fasted counterparts (4.78), which were similar (P greater than .10). Colostrum intake failed to stimulate synthesis from alanine. The oxidation rate for octanoate was similar for fed and limit-fed pigs (.62 and .61 nmol CO2.h-1.mg DNA-1, respectively) but greater (P less than .05) than that observed for fasted counterparts (.36). Oxidation of octanoate (2 mM) was approximately 30-fold greater than for oleate (1 mM); oxidation of the latter was not affected by either colostrum intake or the addition of carnitine (1 mM). The increase in octanoate oxidation, however, did not elicit an increase in glucose synthesis by fasting pigs with either lactate or alanine as precursors. Thus, we conclude that gluconeogenesis is a function of colostrum intake and that reducing equivalents and(or) ATP may not be primary factors limiting glucose synthesis in pigs fasted from birth.     

Evaluation of cimaterol for finishing swine including a drug withdrawal period

One hundred fifty crossbred pigs (55 kg) were allotted by weight, sex and litter to a randomized complete-block design with five dietary treatments, six blocks per treatment and five pigs per pen with sex equalized across treatments. Corn-soybean meal-based diets (.65% lysine) with 0, .25 and .5 mg/kg cimaterol were fed, on an ad libitum basis, to pigs slaughtered at an average pen weight of 104 kg/pig. Drug withdrawal prior to slaughter was 1, 3 and 5 d for pigs fed cimaterol at .25 mg/kg and 1 d for those fed cimaterol at .5 mg/kg of diet. Dietary cimaterol level influenced (quadratic, P less than .01) average daily gain during the first 42 d on test; however, daily feed intake and feed conversion ratio were not affected (P greater than .1). Pigs fed .25 mg/kg cimaterol with a 1-d drug withdrawal had 6.8, 7.7 and 13.5% less 10th rib fat depth and 11.1, 6.1 and 13.3% less P2 fat depth than those subjected to either a 3- or 5-d drug withdrawal or those fed the 0 mg/kg cimaterol diet (control), respectively. Overall, pigs fed cimaterol had 7.9% larger longissimus muscle area and 2.6% more kilograms of muscle than pigs fed the control diet. Cimaterol fed at .5 mg/kg resulted in higher (P less than .05) Warner-Bratzler shear force values and altered the proportion of saturation in some long-chain fatty acids, although the total saturated:unsaturated fat ratio was not affected. Pigs fed no cimaterol had less thaw loss (P less than .05) than did those fed other treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

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)     

Chlortetracycline supplementation of yearling dairy heifers

Chlortetracycline is an antibiotic that is used to increase weight gain, efficiency of gain, carcass grade, and conception rates. The objective of this experiment was to evaluate the effects of supplementation of 350 mg/d of chlortetracycline on ADG, G:F, BCS, thyroxine, and systemic glucose concentrations in yearling dairy heifers. Forty 12-mo-old Holstein heifers (initial BW = 363 +/- 21 kg) were housed in a free-stall barn with ad libitum access to feed and water for 104 d. A transition period was begun 14 d before the age of 12 mo to acclimate the heifers to the diet. The chlortetracycline-fed group (n = 20) consumed 328 +/- 8.2 mg of chlortetracycline/heifer daily. Measurements for BW, withers and hip heights, BCS, and health score were recorded weekly. Dry matter intake was measured daily. Blood was sampled every 4 d to determine plasma thyroxine and glucose concentrations and every 2 d to determine progesterone concentrations. Heifers were artificially inseminated on the first observed standing heat after 13 mo of age. There were no effects of chlortetracycline on ADG, G:F, withers and hip heights, BCS, blood glucose concentrations, peak progesterone concentrations, health, or conception rate. There was an interaction between treatment and time for chlortetracycline on serum thyroxine concentration. In the beginning of the experiment, serum thyroxine concentration was lower in heifers supplemented with chlortetracycline. There was no difference between treatments in thyroxine concentration at the end of the experiment. Chlortetracycline supplementation was not beneficial for yearling dairy heifers.     

Bioavailability of oxytetracycline, tetracycline and chlortetracycline after oral administration to fed and fasted pigs

The disposition of oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) was measured after intravenous and oral administration to pigs. Eighteen healthy pigs (six for each compound) weighing 22-43 kg received a dose of 10 mg/kg intravenously, and 45 mg/kg (OTC and TC) or 40 mg/kg (CTC) orally in both a fasted and a fed condition in a three-way crossover design. The three tetracyclines were present in plasma up to 30 hours after intravenous and after oral administration to fasted as well as fed pigs. The volume of distribution was 1.4, 1.2 and 0.7 L/kg body weight for OTC, TC and CTC respectively. The bioavailability was in general low for all the three tetracyclines. The presence of food did not affect the bioavailability of OTC, which was only 3% in both fasted and fed pigs. For TC there was a significantly higher bioavailability in fasted (18%) than in fed (5%) pigs, whereas for CTC the difference was not significant, being 11% in fasted vs. 6% in fed pigs. Even though the presence of food affected the bioavailability only for TC, it prolonged the absorption phase for all three tetracyclines. Based on the bioavailability and the resulting plasma concentrations, it is concluded that it is not possible to obtain a therapeutically active concentration in plasma or tissues after oral administration of any of the three tetracyclines to fed or fasted pigs.     

Performance of finishing pigs in hoop structures and confinement during winter and summer

Performance of finishing pigs in hoop structures or confinement during winter and summer was evaluated in Iowa. Hoops are large, tent-like shelters with cornstalks or straw for bedding. During summer and winter seasons for 3 yr (1998 to 2001), six trials were conducted using three hoop barns (designed for 150 pigs per pen, one pen per hoop) or a mechanically ventilated confinement barn with slatted floors (designed for 22 pigs per pen, six pens in the barn). A total of 3,518 pigs started the trials. Summer trials were June through October, and winter trials were December through April. Target stocking density was 1.11 m2/pig in hoops and 0.74 m2/pig in confinement. Identical corn-based diets were fed ad libitum from 16 to 118 kg for 127 d. Pigs were scanned before harvest for backfat and loin muscle area. When seasons were merged (season x housing interaction, P > or = 0.05), hoop-fed pigs had more backfat (21.8 +/- 0.3 vs 20.8 +/- 0.2 mm; P < 0.001), smaller loin muscle area (41.3 +/- 0.3 vs 43.0 +/- 0.2 cm2; P < 0.001), less lean percentage (51.1 +/- 0.2 vs 52.1 +/- 0.1%; P < 0.001), and less yield (74.9 vs 75.8 +/- 0.1%; P < 0.001) than confinement-fed pigs. When season x housing type interactions were observed (P < 0.004), summer hoop-fed pigs had greater ADG (834 +/- 5 vs 802 +/- 3 g/d; P < 0.001), required fewer days to 113 kg (174.9 +/- 0.9 vs 178.5 +/- 0.6 d; P < 0.01), had similar ADFI (2.40 +/- 0.03 vs 2.35 +/- 0.02 kg/d, as-fed basis) and gain:feed (G:F; 348 +/- 4 vs 342 +/- 3 g/kg) compared with confinement-fed pigs. Lean gain/day and efficiency of lean gain did not differ between housing systems. During winter, hoop-fed pigs had similar ADG (794 +/- 5 vs 801 +/- 3 g/ d), required more days to 113 kg (176.7 +/- 0.9 vs 172.9 +/- 0.6 d; P < 0.01), had greater ADFI (2.54 +/- 0.03 vs 2.35 +/- 0.02; P < 0.001), less G:F (313 +/- 4 vs 341 +/- 3; P < 0.001), less lean gain/day (312 +/- 2 vs 322 +/- 1 g/d; P < 0.01), and less efficiency of lean gain (130 +/- 2 vs 144 +/- 1 g lean gain/kg feed; P < 0.01) than confinement-fed pigs. Percentage of mortalities and culls did not differ between housing systems. During summer, there was a trend for fewer light pigs at marketing (< 100 kg) from hoops (0.8 vs 1.7%; P = 0.10). During winter, there were more light pigs at marketing from hoops (3.9 vs 1.3%; P = 0.01) than from confinement. Bedding use in hoops was 92 and 122 kg/pig for summer and winter, respectively. Performance of finishing pigs in bedded hoop structures depends in part on thermal environment.     

EFFECT OF FEEDING REGIMEN ON GASTRIC ULCERATION OF THE PARS OESOPHAGEA OF INTENSIVELY RAISED PIGS

Three groups of pigs (total 23 pigs) were fed ad libitum from weaning until market weight and these were compared with three groups of pigs (total 26 pigs) fed ad libitum until 12 weeks of age, and then fed on a restricted regimen (twice per day) until marketed.
There was a significant difference in degree of ulceration between the two feeding regimens; those pigs fed ad libitum had the most severe gastric ulcers.
The pigs fed ad libitum , had significantly less agonistic interactions per minute than did the restricted fed pigs. Growth rates of the pigs from weaning to market weight did not differ significantly in the two regimens, although the average pig on ad libitum feeding consumed 182.9 kg, and the restricted fed pigs ate 148.2 kg per pig.     

Effects of level of feed intake on nitrogen, amino acid and energy digestibilities measured at the end of the small intestine and over the total digestive tract of growing pigs

A replicated trial of 3 X 3 Latin square design was conducted with growing pigs (about 29 kg initially) to determine the effects of different levels of feed intake on nutrient digestibilities determined near the end of the small intestine and over the total digestive tract. Pigs were fiftted with simple T-cannula. Feeding levels were ad libitum (AL) and limit-fed (4.5 or 3% of body weight/d). A 16% sorghum-soybean diet was used. Limit-fed pigs were fed at 12-h intervals and water was limited to 2 liters/kg of diet; AL pigs received water ad libitum. Consumption by pigs fed ad libitum averaged 6% of body weight/d. Neither feeding method nor level greatly affected nutrient digestibility measured at the end of the small intestine, but values tended to decrease as feeding level decreased. Comparisons of nutrient digestibility between AL and limit-fed pigs ranged from 2.9 to .7 percentage units, with only N (P less than .10) and methionine (P less than .05) reaching significance. Differences between 4.5 and 3% were slightly larger, ranging from 4.3 to -.2 percentage units, with differences for dry matter, N, gross energy and several amino acids reaching significance (P less than .10 or P less than .05). Measured over the total tract, observed differences among feeding levels were again small, but the trend was reversed, with digestibilities increasing as feeding level decreased. The estimated percentage of ingested nutrients that disappeared in the large intestine increased as feeding level decreased.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of two different feed levels on the development of the reproductive organs in boars.

The aim of the present investigation was to study the development of the reproductive organs in boars fed restrictively and fed ad libitum. A total of 120 boars were purchased by the experimental station at 20 kg live weight. Three groups of 4 litter mates were selected after each of 10 A.I. boars (7 Swedish Landrace and 3 Swedish Yorkshire). The dams were unselected sows from pigletproducing herds. Two boar pigs from each litter were allocated at random among 2 treatment groups. One group ( = N) was fed restrictively and the other group (=A) ad libitum. The boars were slaughtered at 90 kg or at 120 kg live weight. The reproductive organs were removed at slaughter and examined.The ad libitum fed boars were about 2 weeks younger at slaughter than those fed restrictively (16.5 and 13.7 days respectively for the 2 weight classes). The weights of the testes were somewhat higher for ad libitum fed than for restrictively fed boars. Out of 94 examined pairs of testes, epididymides, seminal vesicles and bulbo-urethral glands, the left was heavier than the right in 68%, 62%, 48%, and 36%, respectively. Fewer (4/23) ad libitum fed than restrictively fed boars (9/26) had reached puberty at 90 kg live weight. Age at puberty thus seems to be less variable than body size in boars.     

饲喂模式对猪生长性能、养分消化率和肠道微生物组成的影响

本试验旨在探究不同饲喂模式对猪生长性能、养分消化率和肠道微生物组成的影响。选择120头平均初始体重(26.0±0.4)kg的生长猪(公、母各半),按体重和性别随机分为自由采食组(FA)和限制饲喂频率组(每天饲喂3次,M3),每个处理10个重复,每个重复6头猪,试验期共28 d。结果表明:M3组平均日采食量和耗料增重比均显著低于FA组(P<0.05);饲喂模式的改变对养分表观全肠道消化率无显著影响(P>0.05);M3组血浆尿素氮和游离脂肪酸水平显著低于FA组(P<0.05),而胰岛素水平显著高于FA组(P<0.05);饲喂模式对猪粪便微生物组成有一定影响,在门水平上,M3组拟杆菌门丰度显著低于FA组(P<0.05),柔膜菌门和疣微菌门丰度显著高于FA组(P<0.05);在属水平上,M3组Prevotellaceae_UCG-003、Ruminococcaceae_UCG-010、Ruminococcaceae_NK4A214_group、Rikenellaceae_RC9_gut_group和Coprostanoligenes_group的丰度显著高于FA组(P <0.05),而Selenomonas、Roseburia、Prevotella_2、Prevotella_7、Prevotella_9、Anaerovibrio和Alloprevotella的丰度显著低于FA组(P<0.05)。综上,饲喂模式对生长猪养分消化率无显著影响,限制饲喂频率可改变肠道微生物组成并改善生长猪饲料报酬。     

Compensatory growth and nitrogen balance in grower-finisher pigs

Sixteen castrated male pigs (averaging 21.2 +/- 4.9 kg) were used in two trials to investigate the effect of dietary amino acid content during the grower phase on growth performance and N balance. In each trial, pigs were assigned randomly to corn-soybean meal grower diets formulated to contain 5.0 or 11.0 g lysine/kg (as-fed basis). Common Finisher 1 and 2 diets were offered when pigs reached 51.2 +/- 3.3 and 79.5 +/- 3.4 kg, respectively. Pigs were placed in metabolism crates for a 9-d period during each of the grower, Finisher 1, and Finisher 2 phases when they weighed 43.3 +/- 3.9, 70.4 +/- 4.9, and 90.5 +/- 3.8 kg, respectively, to determine N balance. Blood samples were taken from each pig periodically after an overnight fast. Pigs were allowed ad libitum access to feed and water, except during the three adaptation/collection periods. There were no diet x trial interactions; thus, the data were combined. Pigs fed the low-amino acid grower diet grew more slowly and less efficiently (P < 0.001) during the grower phase and had more ultrasound backfat (P = 0.010) at the end of the grower phase than those fed the high-amino acid grower diet. During the Finisher 1 phase, however, pigs fed the low-amino acid diet grew more efficiently (P = 0.012) than those fed the high-amino acid diet, and the grower diet had no effect on overall weight gain, carcass traits, lean accretion, or meat quality scores. Although pigs fed the low-amino acid diet had less serum urea N (P < 0.001) and more glucose (P = 0.009) at 43.3 kg, there seemed to be no clear, long-term effect of the grower diet on serum metabolites. During the grower phase, pigs fed the high-amino acid diet consumed more N (P < 0.001), had higher apparent N digestibility (P = 0.041), N utilization (P = 0.027), and N retention (P < 0.001), and excreted more fecal (P = 0.034) and urinary (P < 0.001) N than those fed the low-amino acid diet. Pigs fed the low-amino acid grower diet, however, had a higher N utilization (P = 0.024) during the Finisher 1 phase, and excreted less urinary N during both the Finisher 1 (P = 0.029) and 2 (P = 0.027) phases than those fed the high-amino acid grower diet. These results indicate that pigs subjected to early dietary amino acid restrictions compensated completely and decreased N excretion during both the restriction and realimentation phases. Compensatory growth can, therefore, have a positive effect not only on the overall efficiency of pig production but also on environment.     

Effect of sex and reproductive status on sucrose preference, food intake, and body weight of dogs

In a study of preferences for diets containing 1% to 20% sucrose over a bland diet, both female and male dogs preferred the diets containing sucrose over a bland diet, but female dogs had a significantly (P less than 0.05) greater preference for 1% sucrose than did males. Differences between sexes were not observed at the higher concentrations. Mean daily caloric intake was calculated for 12 bitches fed ad libitum during metestrus, estrus, and anestrus, as determined from metachrome-stained vaginal smears. Mean daily caloric intake was lowest during estrus (149 +/- 17 kcal/kg of body weight), was higher during metestrus (159 +/- 8 kcal/kg of body weight), and was highest (175 +/- 9 kcal/kg of body weight) during anestrus. Ovariohysterectomized bitches gained significantly (P less than 0.01) more weight (1.3 +/- 0.3 kg) in the first 10 days after surgery than did sham operated controls (0.3 +/- 0.1 kg). Food intake also was significantly greater ( less than 0.01) in the ovariohysterectomized bitches (1,708 kcal/day) than in the sham operated controls (1,423 kcal/day). Depth of subcutaneous fat in shoulder, rib, and rump areas of ovariohysterectomized bitches was not significantly different from that of intact bitches.     

The effect of feed intake on ileal rate of passage and apparent amino acid digestibility determined with or without correction factors in pigs

The apparent ileal digestibilities of amino acids and rate of passage were evaluated in pigs (BW = 78.3 +/- 7.4 kg) fed a semipurified diet. The pigs were fed 1.82, 2.73, or 3.65 kg DMI/d. The highest level of feed intake was considered to be ad libitum feeding. The pigs were fed according to a 3 x 3 Latin square design and were allowed to adapt to each experimental diet for 5 d. This was followed by 1 d of continuous collection of ileal digesta and a 2nd d of continuous collection separated into six 2-h postprandial time blocks. Ytterbium chloride hexahydrate was used to determine rate of passage. The ileal digestibilities of amino acids and rate of passage were unaffected (P > 0.05) by level of feed intake. The use of correction factors to more accurately express amino acid concentrations in the diet and digesta affected (P < 0.05) the apparent ileal digestibility coefficients of some amino acids.