The effects of branched-chain amino acids on sow and litter performance.
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Sows (n = 306; PIC, Line C-19; average parity 2.1) were used to evaluate the interrelationship between valine, isoleucine, and leucine on sow and litter performance. Our objective was to determine whether the increase in litter weaning weight associated with added dietary valine is specific for valine or a result of the total branched-chain amino acid (i.e., isoleucine and[or] leucine) concentration of the diet. Eight dietary treatments (36 to 41 sows/treatment) were arranged as a 2 x 2 x 2 factorial with two levels of valine (.80 and 1.20%), isoleucine (.68 and 1.08%), and leucine (1.57 and 1.97%). This provided total branched-chain amino acid levels of 3.05, 3.45, 3.85, and 4.25%. The lowest level of each branched-chain amino acid was similar to that in a .90% lysine corn-soybean meal diet containing .15% L-lysine HCl. Amino acids other than valine, isoleucine, and leucine met or exceeded their suggested estimates relative to lysine using ratios derived from the National and Agricultural Research Councils. Average number of pigs on d 2 of lactation was 11.2, and average lactation length was 20.9 d. Number of pigs weaned (x = 10.6), sow ADFI (x = 5.85 kg), and sow weight loss (x = 4.25 kg) were not affected by dietary treatment (P > .10). Sow backfat loss (P < .02), litter weaning weight (P < .04), and litter weight gain from d 2 to weaning (P > .05) increased as dietary valine increased. Litter weight at weaning and litter weight gain were not affected by dietary isoleucine (P > .80) or leucine (P > .60). Sixteen or 17 sows per treatment (129 total) were milked manually on d 14 to 16 of lactation. Increasing dietary valine tended to increase milk urea N (P < .07) but did not affect milk DM, CP, fat, lactose, or ash. Increasing dietary isoleucine or leucine had no effects on milk composition. These results confirm the importance of dietary valine for increased litter weaning weight, independent of either additional dietary leucine or isoleucine. (+info)
A new phytase expressed in yeast effectively improves the bioavailability of phytate phosphorus to weanling pigs.
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We have recently expressed a new phytase enzyme in a yeast system. Three experiments with a total of 140 weanling crossbred pigs were conducted to examine the efficacy of this enzyme in improving the bioavailability of phytate-P in corn-soybean meal diets to young pigs. Experiment 1 compared the efficacy of this new phytase with a commercially available phytase (Natuphos, BASF) for 4 wk at an inclusion level of 1,200 U/kg of diet. Experiment 2 compared the responses of pigs to four doses of the new phytase supplementation (300, 600, 900, and 1,200 U/kg of diet) for 4 wk. Experiment 3 compared the efficacy of this new phytase and Natuphos at a marginally optimal dose (700 U/kg of diet) for 5 wk. A group of pigs were fed the P-deficient basal diet as a negative control in Exp. 1, and a group of pigs were fed the basal diet plus .17 or .22% inorganic P as a positive control in all experiments. In Exp. 1, pigs fed the two sources of phytase had similar ADG (564 vs 567 g), gain/feed (.597 vs .589), plasma inorganic P concentrations (8.9 vs 8.4 mg/dL), and mobility scores (4.25 vs 4.46) that were higher (P < .05) than those of the negative control. In Exp. 2, plasma inorganic P concentration was a fairly linear response to the phytase dose (r > .83) at wk 1 and 2. Overall ADG of pigs also tended to increase with the phytase dose (P = .15). In Exp. 3, pigs fed the two sources of phytase had ADG (483 vs 506 g) similar to that of the positive control (508 g). These two groups also had similar plasma inorganic P concentrations (7.7 vs 7.4 mg/dL) that were lower (P < .05) than those of the positive control group (9.7 mg/dL). There was no significant effect of dietary treatments on ADFI in all three experiments. In conclusion, our new phytase was as effective as Natuphos, at the inclusion level of 700 or 1,200 U/kg of a P-deficient, corn-soybean meal diet, in improving phytate-P utilization by young pigs. (+info)
Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats exposed to frequency-modulated microwave fields.
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In a 2-year bioassay, we exposed Fischer 344 rats to a frequency-modulated (FM) signal (836.55 MHz +/- 12.5 KHz deviation) simulating radiofrequency exposures in the head of users of hand-held mobile phones. We tested for effects on spontaneous tumorigenicity of central nervous system (CNS) tumors in the offspring of pregnant rats and also for modified incidence of primary CNS tumors in rats treated with a single dose of the neurocarcinogen ethylnitrosourea (ENU) in utero. ENU dosage (4 mg/kg) was selected to give an expected brain tumor incidence of 10-15% over the mean life span of 26 months. Pregnant dams (n = 102) were randomly assigned to six groups. Their offspring were treated as cohorts in each of the six groups (n = 90 per group; total, n = 540): Sham ENU/Sham Field, Sham ENU/Field Exposed, ENU/Sham Field, ENU/Field Exposed, ENU/Cage Control, and Sham ENU/Cage Control. Intermittent field exposures began on gestation day 19 and continued until weaning at 21 days, resuming thereafter at 31 days and continuing until experiment termination at 731-734 days. Energy absorption rates (SARs) in the rats' brains were similar to localized peak brain exposures of a phone user (female, 236 g, 1.0 W/kg; male, 450 g, 1.2 W/kg). Of the original 540 rats, 168 died before the termination of the experiment. In these rats, ENU significantly reduced survival from a mean of 708 days in three groups without ENU treatment to 645 days in three groups treated with ENU (P < 0.0005). There were no effects on survival attributable to FM field exposure in either ENU-treated or in sham-treated groups. Spontaneous CNS tumor incidence in control groups was 1.1-4.4% but sharply higher in rats receiving ENU (14.4-22.2%; P < 0.0001). No FM field-mediated changes were observed in number, incidence, or histological type of either spontaneous or ENU-induced brain tumors, nor were gender differences detected in tumor numbers. These negative findings with FM fields contrast with our study using standard digital phone fields pulsed on and off at 50/se, where a trend was noted toward reduced incidence of both spontaneous and ENU-induced CNS tumors (W. R. Adey et al., Radiat. Res., 152: 293-302, 1999). Although consistent but not attaining significance in the experiment overall (spontaneous CNS tumors, P < 0.08 one-tailed; P < 0.16 two-tailed; ENU-induced CNS tumors, P < 0.08 one-tailed, P < 0.16 two-tailed), the trend was significant (P < 0.015 one-tailed, P < 0.03, two-tailed) in rats that received ENU and died prior to experiment termination, with a primary brain tumor as the cause of death. We discuss differences in the signaling structure of digital and FM fields. Certain bioeffects induced by either amplitude-modulated or pulsed radiofrequency fields at athermal levels have not been seen with fields of similar average power but unvarying in intensity (continuous wave or frequency-modulated fields). (+info)
Genetic parameters among weight, prolificacy, and wool traits of Columbia, Polypay, Rambouillet, and Targhee sheep.
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Genetic parameters for Columbia, Polypay, Rambouillet, and Targhee sheep were estimated using REML with animal models for prolificacy, weight, and wool traits. All bivariate analyses included a covariance between additive genetic effects for the two traits plus appropriate additional covariances. Number of observations by breed ranged from 5,140 to 7,095 for prolificacy traits, from 7,750 to 9,530 for weight traits, and from 4,603 to 34,746 for wool traits. Heritability estimates ranged from .03 to .11 for prolificacy traits (litter size at birth and litter size at weaning), from .09 to .26 for weight traits (birth weight and average daily gain), and from .25 to .53 for wool traits (fleece weight, fleece grade and staple length). Estimates of direct genetic correlations among prolificacy and among weight traits were positive and ranged from .58 to 1.00 and .18 to 1.00, respectively. Estimates of direct genetic correlation between fleece weight and staple length were positive (.50 to .70) but were negative between fleece weight and fleece grade (-.60 to -.34) and between staple length and fleece grade (-.72 and -.40). Prolificacy and wool traits were essentially uncorrelated. Weight and prolificacy traits were slightly positively correlated. Weight traits had a moderate positive direct genetic correlation with fleece weight and staple length, but were uncorrelated with fleece grade. These estimates of genetic parameters between prolificacy, weight, and wool traits can be used to construct multiple-trait selection indexes for dual-purpose sheep. (+info)
Hand-feeding and gentling influence early-weaned lambs' attachment responses to their stockperson.
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Artificially reared herbivores are highly dependent on the stockperson at an early age in order to learn to drink from an artificial milk provider. This period of training may be a determinant for the animals' subsequent responses toward humans. However, long-term responses may also depend on the human contact (e.g., visual, physical interactions, gentling, and handling) provided to the young lambs after this training period. We examined whether different levels of subsequent contact (no visual and physical contact, stroking, and feeding reward) affect long-term attachment responses of lambs to the caretaker that provided the subsequent contact, after a common initial training period for artificial feeding provided by another person. Ewe lambs (n = 45) were artificially reared from multinippled buckets in groups of three. All the lambs were trained by a stockperson (S1) to suck from the bucket (4.4 +/- .3 sessions of 3 min per animal for the first 2 d of life). Subsequently, 15 lambs received no further human contact (T0). Fifteen other lambs received only stroking from a second stockperson (S2) for 6 min three times a day during the first 4 wk (T1). The remaining 15 lambs (T2) were stroked and bottle-fed by S2 during the same posttraining period as for T1. Tests were performed at 4, 6 (just before weaning), 9, and 13 wk of age in an unfamiliar arena marked in a grid pattern. The test procedure included three successive parts: 1) isolation for 1 min; 2) S2 presence for 2 min; and 3) isolation for 1 min. The T0 lambs spent a similar amount of time in the grid square close to S2 regardless of whether he was present. The T1 and T2 lambs spent more time close to S2 than T0 (P < .01), and T2 spent more time close than T1 (P < .05). In the presence of S2, T2 vocalized less (P < .01) than T0, and T1 did not differ from either T2 or T0. The T2 lambs also crossed fewer squares than T0. When S2 left the arena, T2 vocalized more (P < .01) than T0 and more (P < .05) than T1, and T1 had a tendency to vocalize more (P = .08) than T0. Differences persisted with increasing age. Human contact, especially stroking and feeding, during the 4 wk following initial training strongly and durably influenced the lambs' response not only to the appearance but also to the disappearance of a familiar stockperson. This last result supports the idea that lambs could form a social bond with their stockperson. (+info)
Developmental changes in cholesterol 7alpha- and 27-hydroxylases in the piglet.
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Hepatic cholesterol 7alpha-hydroxylase (CYP7A) and sterol 27 hydroxylase activities were measured in fetal, newborn, suckling, and weaned piglets from 76 d into gestation to 49 d of age. Hepatic CYP7A activity was not detected in fetal microsomes, but it increased to 6.8 +/- 2.6 pmol/min x mg(-1) protein in suckling piglets at 21 d of age and to 18.2 +/- 2.5 in weaned piglets at 49 d of age. Hepatic CYP7A activity was not different between 49-d-old piglets weaned at 21 d and piglets suckled for 49 d (18.9 +/- 2.6 and 18.2 +/- 2.5 pmol/min x mg protein, respectively). Fasting for 14 h decreased CYP7A activity by 86% in both suckled and weaned piglets. Cholesterol 7alpha-hydroxylase activity remained decreased for at least 5 h after refeeding. Sterol 27-hydroxylase activity was also undetectable near birth, but was detectable by 21 d of age. Postnatally, sterol 27-hydroxylase activity was not influenced by age or suckling and weaning, as was CYP7A. Sterol 27-hydroxylase was decreased by 80% in piglets deprived of feed compared with piglets given free access. In contrast to CYP7A activity, 27-hydroxylase activity returned within 5 h after refeeding to levels observed in piglets given ad libitum access to feed. Similar to CYP7A enzyme activity, hepatic CYP7A mRNA was not detected in newborn piglets, but increased from 2.7 +/- 1.7 pg mRNA/microg RNA in suckling piglets at 21 d to 13.7 +/- 1.2 in 49-d-old piglets weaned at 21 d. As with enzyme activity, feed deprivation decreased CYP7A mRNA to barely detectable levels (< .5 pg/microg RNA), and which remained decreased for at least 5 h following refeeding (.6 +/- .3 and 2.67 +/- .4 pg mRNA/microg RNA for suckled and weaned piglets, respectively). In piglets allowed free access to feed, CYP7A mRNA concentrations were associated positively (P = .001) with enzyme activity. These results suggest that developmental regulation of CYP7A activity is the result of a pretranslational mechanism. (+info)
Impact of dietary lysine intake during lactation on follicular development and oocyte maturation after weaning in primiparous sows.
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Primiparous sows (n = 36) were used to evaluate the effects of dietary lysine intake in lactation on follicular development and oocyte maturation after weaning. Sows were assigned randomly to one of three diets containing .4% (low lysine, LL), 1.0% (medium lysine, ML), or 1.6% (high lysine, HL) total lysine. All diets contained 2.1 Mcal NE/kg and exceeded NRC (1988) requirements for all other nutrients. Actual lysine intakes over an 18-d lactation were 16, 36, and 56 g/d for sows consuming LL, ML, and HL, respectively. Ovarian data were analyzed for sows determined to have been slaughtered during the first proestrus period after weaning, using previously established criteria. Compared with sows fed ML and HL, sows fed LL tended to have lower uterine weight, follicular fluid volume, and follicular fluid (FF) estradiol (E2) content (P < .15), but similar ovarian weight and follicular fluid IGF-I concentration. Within the largest 15 preovulatory follicles, sows fed LL had a lower percentage of large (> or = 7.0 mm) follicles (33 vs 50 and 58%; P < .01) and a higher percentage of medium (5.5 to 7.0 mm) follicles (62 vs 44 and 39%; P < .01) but a similar percentage of small (< or = 5.5 mm) follicles (4.4 vs 5.9 and 3.7%; P > .15), respectively, compared with sows fed ML or HL. Standardized pools of oocytes aspirated from follicles of prepubertal gilts were incubated for 44 h with pooled FF recovered from the largest 15 follicles of each experimental sow. Fewer oocyte nuclei matured to metaphase II of meiosis when cultured with FF recovered from sows fed LL, than from sows fed ML or HL (47.1 vs 59.8 and 63.8%, respectively; P < .01). Our results suggest that low lysine (protein) intake in primiparous lactating sows impaired follicular development and reduced the ability of follicles to support oocyte maturation. However, high compared with medium lysine (protein) intake had no further positive effects on ovarian function. (+info)
Growth promotion effects and plasma changes from feeding high dietary concentrations of zinc and copper to weanling pigs (regional study).
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An experiment was conducted to determine the effect of high dietary intakes of Zn and Cu and their combination on growth performance of weanling pigs with diverse health status and management strategies. Twelve experiment stations cooperated and used a total of 1,356 pigs that averaged 6.55 kg BW and 22.2 d age at weaning. The four dietary treatments, all of which met or exceeded NRC requirements, were 1) control, 2) 3,000 ppm Zn (from Zn oxide), 3) 250 Cu ppm (from Cu sulfate), or 4) 3,000 ppm Zn and 250 ppm Cu. The diets were fed as a complex Phase I diet (1.4% lysine) for 7 d followed by a Phase II diet (1.2% lysine) for 21 d. Chlortetracycline (220 ppm) was added to all diets. Fecal color (1 = yellow to 5 = black) and consistency (1 = very firm to 5 = very watery) were scored daily for 3 wk. At the end of the 28-d study, 412 pigs were bled at five stations, and plasma Cu, Zn, and Fe concentrations were determined at one station with atomic absorption spectrophotometry. Average daily gain (375, 422, 409, 415 g/d), feed intake (637, 690, 671, 681 g/d), and gain/feed (586, 611, 611, 612 g/kg) were improved (P < .01) by the addition of Zn and(or) Cu. Significant Cu x Zn interactions imply that the responses to Zn and Cu were independent and not additive. There were significant (P < .01) Zn and Cu effects and a Zn x Cu interaction on fecal color (3.17, 3.24, 4.32, 3.57) and consistency (2.39, 2.14, 2.14, 2.13). Dietary additions of Cu and Zn resulted in elevated plasma concentrations of Cu and Zn, respectively. These data indicate that pharmacological additions of 3,000 ppm Zn (oxide) or 250 ppm Cu (sulfate) stimulate growth beyond that derived from intakes of Zn and Cu that meet nutrient requirements. However, the combination of Zn and Cu did not result in an additive growth response. (+info)