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R D Boyd

Publications and source records attributed to R D Boyd.

At least 19 recordsLinked to original sources
PubMed2005

Preservation of bone collagen from the late Cretaceous period studied by immunological techniques and atomic force microscopy.

Late Cretaceous avian bone tissues from Argentina demonstrate exceptional preservation. Skeletal elements are preserved in partial articulation and suspended in three dimensions in a medium-grained sandstone matrix, indicating unusual perimortem taphonomic conditions. Preservation extends to the microstructural and molecular levels. Bone tissues respond to collagenase digestion and histochemical stains. In situ immunohistochemistry localizes binding sites for avian collagen antibodies in fossil tissues. Immunohistochemical studies do not, however, guarantee the preservation of molecular integrity. A protein may retain sufficient antigenicity for antibody binding even though degradation may render it incapable of original function. Therefore, we have applied atomic force microscopy to address the integrity and functionality of retained organic structures. Collagen pull-off measurements not only support immunochemical evidence for collagen preservation for antibody recognition but also imply preservation of the whole molecular integrity. No appreciable differences in collagen pull-off properties were measured between fossil and extant bone samples under physiological conditions.

Animals↗
PubMed2004

Phosphorus requirements of growing-finishing pigs reared in a commercial environment.

The objective of this study was to identify available phosphorus (aP) requirements of pigs reared in commercial facilities. In a preliminary study, 600 gilts (PIC) were allotted randomly to low (0.30%) or high (0.37%) dietary aP from 43 to 48 kg BW, and later to 0.19 or 0.27% aP from 111 to 121 kg BW. No differences were observed (P = 0.42 to 0.88) in ADG, but G:F from 43 to 48 kg tended to improve (P = 0.07) for pigs fed low aP. Results suggested that the aP requirement was at or below 0.30 and 0.19%. These concentrations were used to titrate aP requirements in Exp. 1 and 2. In Exp. 1, 1,260 gilts (initially 33.8 kg) were allotted randomly to one of five dietary treatments containing 0.18, 0.22, 0.25, 0.29, or 0.32% aP, corresponding to 0.5, 0.6, 0.7, 0.8, or 0.9 g of aP/Mcal of ME. There were 28 pigs per pen and nine pens per treatment. From d 0 to 14, increasing aP increased ADG (linear, P = 0.03) and G:F (quadratic, P = 0.07), with the greatest response observed as aP increased from 0.18 to 0.22% (G:F breakpoint = 0.22%). However, from d 0 to 26, no differences (P = 0.12 to 0.81) were observed for any growth traits. Pooled bending moment of the femur, sixth rib, and third and fourth metatarsals increased (linear, P = 0.007) with increasing aP. In Exp. 2, 1,239 gilts (initially 88.5 kg BW) were randomly allotted to one of five dietary treatments containing 0.05, 0.10, 0.14, 0.19, or 0.23% aP, equivalent to 0.14, 0.28, 0.39, 0.53, or 0.64 g of aP/Mcal of ME. The diet with 0.05% aP contained no added inorganic P. From d 0 to 14, increasing aP increased (linear, P = 0.008 to 0.02) ADG and G:F; however, from d 0 to 28, increasing aP had no effect (P = 0.17 to 0.74) on growth performance. Increasing aP increased (linear, P < 0.001 to 0.04) metacarpal bone ash percent and bending moment. Results suggest that 33- to 55-kg pigs require approximately 0.22% aP, which corresponds to 0.60 g of aP/Mcal of ME or 3.30 g of aP/d to maximize ADG and G:F compared with NRC (1998) estimates of 0.23%, 0.70 g of aP/Mcal of ME, and 4.27 g of aP/d for 20- to 50-kg pigs. Finishing pigs (88 to 109 kg) require at least 0.19% aP, corresponding to 0.53 g of aP/Mcal of ME or 4.07 g aP/d compared with NRC (1998) estimates of 0.15%, 0.46 g of aP/Mcal of ME and 4.61 g of aP/d for 80- to 120-kg pigs. However, the percentage of bone ash and bending moment continued to increase with increasing aP. These data also suggest that complete removal of supplemental P in diets for finishing pigs (>88 kg) will decrease ADG and G:F.

Animal Feed↗
PubMed2003

Early weaning to reduce tissue mobilization in lactating sows and milk supplementation to enhance pig weaning weight during extreme heat stress.

This study was conducted to determine the effect of reduced lactation length and supplemental milk replacer (MR) during high ambient temperatures. Thirty nine primiparous and 100 multiparous sows (PIC, Franklin, KY, C-22) were used in a 2 x 2 x 2 factorial arrangement of treatments. Treatments consisted of two lactation room temperatures (21 degrees C [TN] and 32 degrees C [HOT]), two lactation lengths (14 or 19 d), and two parity groups (primiparous, multiparous). Pigs were either: 1) sow-reared to 19 d or 2) sow-reared to 14 d, and then reared to 19 d with MR after sow removal. All sows were fed the same diet (1.07% lysine, 3,366 kcal of ME/kg). Sows were weighed and ultrasound for backfat thickness (BF) and longissimus muscle area (LMA) within 6 h after farrowing and at the time of sow removal (d 14 or 19). Pigs were individually weighed at weaning (d 19) and after a 47-d nursery period (d 66). Heat stress increased sow weight loss (-13.35 kg, P < 0.01) and decreased sow feed intake (4.63 kg/d, P < 0.01) during lactation compared with sows in TN (+4.5 kg and 7.5 kg/d, respectively). Early weaning (d 14) during heat stress decreased maternal weight loss (-10.1 vs. -16.6 kg, P < 0.01). Primiparous sows lost more BF in both environments (-2.60 vs. -1.56 mm, P < 0.05), and both parity groups lost more BF (-3.35 vs. -2.3 mm, P < 0.10) and LMA (-1.82 vs. -0.77 cm2, P < 0.05) when lactating for 19 d in the HOT environment than those lactating for 14 d. Pigs nursing primiparous and multiparous sows in the HOT environment and provided MR had heavier individual 19-d weights (7.37 and 8.12 kg/ pig, respectively) than those nursing to 19 d (5.57 and 6.04 kg/pig, P < 0.01). Milk replacer decreased the difference normally observed in 19-d weights between primiparous and multiparous sow-reared pigs in TN. Pigs fed MR in both environments and nursing multiparous sows had improved weight gains in the nursery compared with pigs nursing sows to 19 d (428 vs. 406 g/d, respectively; P < 0.01), or reared by primiparous sows (444 vs. 390 g/d , respectively; P < 0.01). Sow weaning on d 14 in the HOT environment decreased the wean-to-estrus interval in primiparous sows (22.8 vs. 9.2 d, P < 0.10). This study shows the benefit of early weaning in combination with milk replacer to preserve the sow and to restore pig weaning weights and nursery end weights under heat stress.

Adipose Tissue↗
PubMed2001

Outcome survey of early intensive behavioral intervention for young children with autism in a community setting.

This article presents findings from an outcome survey of the effects of early intensive behavioral intervention (EIBI) for young children with autism in a community setting. Results from both individual case reviews and parent questionnaires are presented, with the data failing to support any instances of'recovery' while still yielding a high degree of parental satisfaction with the treatment. Moreover, a follow-up inquiry into the type of services each child was receiving in his or her post-EIBI setting documents continued dependence on extensive educational and related developmental services, suggesting that the promise of future treatment sparing did not materialize. Limitations of the survey in evaluating community-based EIBI services are discussed along with the need for further research designed to document the effectiveness of services provided to young children with ASD in the community.

Autistic Disorder↗
PubMed2001

Cleanability of soiled stainless steel as studied by atomic force microscopy and time of flight secondary ion mass spectrometry.

The hygienic status of food contact surfaces can deteriorate with wear. Effective cleaning regimes must remove any adsorbed organic material as well as microorganisms. Previous work has determined the extent of surface wear occurring on a stainless steel surface within the food industry, and we have reproduced representative samples in vitro. Two surface analytical techniques, atomic force microscopy and time of flight secondary ion mass spectrometry were combined with fluorescence microscopy to give detailed analysis of stainless steel surfaces fouled with starch and milk powder, then cleaned with water either by a spray or brushing method. It was found that the surface cleanability is affected by the cleaning regime and the surface roughness, not only the average vertical roughness but also by the shape of the surface defects, with sharp scratches more difficult to clean than wider surface defects. Spray cleaning with distilled water was found to be a selective method by preferentially removing proteinaceous material more easily than fatty acid ester material. The analytical techniques employed provided information on selective cleanability and surface topography at a hitherto unexplored level, and the information gained may be of value in the design and investigation of novel cleaning regimes and hygienic surfaces.

Detergents↗
PubMed2001

The effect of nanometer dimension topographical features on the hygienic status of stainless steel.

Wear of food contact surfaces through abrasion may increase the surface roughness and introduce different topographical features. Both of these properties may enhance retention of soil and microorganisms and affect the surface cleanability. To test this hypothesis, stainless steel surfaces with topographical features and surface roughness (Ra) values simulating those of worn in-use surfaces were prepared. Surfaces were imaged and Ra values determined using atomic force microscopy (AFM). These ranged from 23 to 900 nm. Surfaces were sprayed with standardized cell suspensions of Pseudomonas aeruginosa or Staphylococcus aureus and allowed to air dry and were then cleaned using a nonionic detergent delivered via a manual linear cleaning device. There was a 2-log reduction in numbers attached after cleaning, but there was no significant difference (P > 0.05) between the cleanability of the surfaces in terms of the numbers of cells per unit area remaining after cleaning, although cells appeared to be retained within topographical features. Thus, the simulated effect of wear of a hygienic food contact surface did not affect its cleanability after a one-off microbiological soiling event. AFM provided hitherto unavailable information on the topography of worn stainless steel surfaces. In future work, the surfaces will be repeatedly challenged with an organic soil-microorganism mixture after cleaning events, to provide a more rigorous, realistic test.

Disinfection↗
PubMed2001

Microbiological and chemical analyses of stainless steel and ceramics subjected to repeated soiling and cleaning treatments.

Stainless steel and ceramic surfaces were subjected to repeated soiling and cleaning procedures, using a milk powder soil inoculated with Pseudomonas aeruginosa and Staphylococcus aureus, followed by spraying with water with or without 0.1% (vol/vol) nonionic detergent. Test surfaces were removed after 1, 5, 10, and 20 soiling-cleaning cycles and were analyzed for attached microorganisms (total viable count of bacteria removed by swabbing and percentage of coverage of cells plus soil stained with acridine orange). Surfaces were additionally examined using a range of analytical techniques: X-ray photoelectron spectroscopy (XPS), dynamic and imaging secondary ion mass spectroscopy (SIMS), and time-of-flight SIMS. Both microbiological and chemical analyses revealed an accumulation of material over the cycles to a maximum level. Surfaces were conditioned rapidly to saturation with organic material within one cycle (XPS), whereas fouling by microorganisms was less rapid (five cycles). Cleaning with detergent tended to retard the cumulative fouling process when compared with spray cleaning using water alone. The methods described provide a more realistic scenario for testing the cleanability of surfaces routinely found in food processing locations and for screening novel cleaning regimens and/or surface materials. The analytical techniques provide additional information on the kinetics of soiling, which complement the more familiar microbiological methods.

Bacterial Adhesion↗
PubMed2000

Altered calbindin mRNA expression and calcium regulating hormones in rat diabetic pregnancy.

Offspring of rats with diabetes mellitus are at risk of reduced calcium and bone mineral content. Altered expression of the maternal calcium binding proteins, calbindin-D(9K) and calbindin-D(28K), which are involved in renal and placental calcium transport, may underlie these problems.We have investigated the effect of diabetes on circulating concentrations of regulatory hormones with respect to calbindin-D mRNA concentrations. Three rat groups were studied; control (CP), streptozotocin-induced diabetic (DP), and insulin-treated diabetic (DPI) pregnant rats. Calbindin-D(9K) and calbindin-D(28K) mRNA abundance in placenta and maternal kidney were measured at days 7, 15, 18 and 21 of gestation, together with serum or plasma concentrations of 1,25 dihydroxyvitamin D(3) (1, 25(OH)(2)D(3)), parathyroid hormone (PTH), PTH-related protein (PTHrP), calcitonin, oestradiol and IGF-I. An increase in placental calbindin-D(9K) mRNA abundance between days 18 and 21 in CP and DPI rats was severely blunted in the DP rats. In contrast, renal calbindin-D(28K) mRNA abundance was greater at days 7, 15 and 18 in DP compared with CP rats, as was calbindin-D(9K) at day 18. Calcitonin concentrations showed no differences between the groups, and both PTH and IGF-I were reduced over the first half of gestation, unlike the calbindins. In contrast, the concentrations of PTHrP and 1,25(OH)(2)D(3) were reduced at term in the DP group compared with the other two groups. Plasma oestradiol concentrations were lower in DP than in CP rats at days 7, 15 and 18, and most striking was the absence in DP rats of the peak of oestradiol seen at day 18 in CP rats. Despite the similarity between changes in placental calbindin mRNA and 1,25(OH)(2)D(3), previous work has shown placental calbindin-D(9K) regulation to be vitamin-D-independent. These studies produce suggestive evidence, therefore, that PTHrP and oestradiol may be involved in the altered calbindin-D expression by kidney and placenta in rat diabetic pregnancy.

Animals↗
PubMed1999

Effect of hyposmotic challenge on microvillous membrane potential in isolated human placental villi.

This study examined the effect of hyposmotic solutions on the syncytiotrophoblast microvillous membrane potential (Em) in mature intermediate villi isolated from term human placentas. When villi were exposed to a control solution (280 mosmol/kgH2O; 116 mM NaCl) and then to either a 138-hyposmotic (138 mosmol/kgH2O; 37 mM NaCl) or 170-hyposmotic (170 mosmol/kgH2O; 55 mM NaCl) solution, there was a significant hyperpolarization of Em (-5.1 +/- 1.5 mV, P < 0.01 and -5.0 +/- 0.5 mV, P < 0.001, respectively; n = 10), which was reversible on removal of the hyposmotic stimulus. Low-NaCl (37 and 55 mM) solutions made isosmotic with control (i.e., 280 mosmol/kgH2O) by addition of raffinose did not significantly alter Em, suggesting that reducing NaCl concentration per se had no effect on Em. Exposure to 170-hyposmotic solution in the presence of 5 mM BaCl2 depolarized Em by +4.1 +/- 0.7 mV (P < 0.001, n = 6); BaCl2 similarly depolarized Em when added in control solution (+5.6 +/- 1. 1 mV, n = 5). Exposure to 170-hyposmotic solution containing 1 mM DIDS hyperpolarized Em by -9.0 +/- 1.7 mV (P < 0.001, n = 5). This degree of hyperpolarization was significantly greater than that observed in hyposmotic solution alone (P < 0.01) but was not different from the hyperpolarization when DIDS was added to control solution (-7.4 +/- 0.2 mV, n = 6). We conclude 1) that Ba2+-sensitive K+ conductances and DIDS-sensitive anion conductances contribute to the resting potential of the syncytiotrophoblast microvillous membrane and 2) that the syncytiotrophoblast microvillous membrane responds to a hyposmotic stimulus by activating both Ba2+-sensitive K+ and DIDS-sensitive anion conductances.

Chlorides↗
PubMed1999

Ontogenic maturation of the somatotropin/insulin-like growth factor axis.

The ontogeny of the somatotropin/insulin-like growth factor system was examined in well-fed pigs under basal conditions and during a short-term challenge of porcine ST (pST). The study was conducted with two replicates of eight castrate male pigs from 3.8 kg BW (10 d of age) to 92 kg BW (129 d of age). Pigs were reared individually with ad libitum access to milk replacer through 23 d of age. Thereafter, pigs were fed a corn, soybean meal, and dry skim milk diet formulated to exceed nutrient requirements by approximately 30%. Pigs were randomly assigned to receive daily i.m. injections of either 0 (buffer) or 120 microg/kg BW of pST for a duration of 4 d starting at 10, 19, 33, 43, 63, 83, and 125 d of age. Blood was collected via jugular venipuncture on d 0 and 4 of the challenge. Circulating levels of IGF-I were not dramatically affected by age, but levels of IGF-II were low from 10 to 19 d of age and then increased through later stages of growth. Circulating concentrations of IGF binding protein (BP)-3 increased with age (P < .05), but levels of IGFBP-2, a 30-kDa IGFBP, and IGFBP-4 were unchanged (P > .10). The pST challenge reduced plasma urea nitrogen at all ages, but the magnitude of the response was less in younger pigs compared with the maximum response in pigs greater than 30 kg BW (63 d of age). The IGF-I response to the pST challenge also increased from approximately 30% in young pigs to a threefold increase in older pigs. Regardless of age, concentrations of IGF-II were minimally affected by the pST challenge. Circulating levels of IGFBP-3 increased and IGFBP-2 levels decreased in response to the pST challenge, and the magnitude increased with age. The high nutritional status of pigs in the early phases of growth diminished the postnatal changes in IGF-I and IGFBP-2, but not IGF-II or IGFBP-3. Overall, data demonstrate a developmental regulation of the ST/IGF system, with pST challenges altering circulating concentrations of IGF-I, IGFBP-3, and IGFBP-2 coincident with changes in amino acid metabolism.

Amino Acids↗
PubMed1998

Decreased glucose response to insulin is maximal within 24 hours of somatotropin injection in growing pigs.

Porcine somatotropin (pST) administration reduces the sensitivity of pigs to insulin, and after several days of treatment, it alters baseline circulating concentrations of pST, insulin, glucose, and other metabolites. The length of time required to develop this reduction in whole-body insulin sensitivity has not been established. To investigate this, eight castrate pigs received daily injections of either recombinant pST (120 micrograms/kg BW) or exicipient. Intravenous insulin tolerance tests (1.0 microgram/kg BW) were done before the first pST injection (Day 0) and on Day 1, 3, 5, and 8 of pST treatment. Control animals had insulin tolerance tests on Day 0 and again on Day 8 of treatment. By Day 8, the glucose response to the insulin tolerance tests in pST-treated pigs was 45% of the response of the control group (P < 0.01). Glucose response areas between Day 1, 3, 5, and 8 of pST treatment were not different (P > 0.10). The maximum effect of pST on glucose response to insulin was achieved by Day 1. Therefore, factors responsible for the development of reduced whole-body insulin sensitivity in pST-treated pigs are fully expressed within 21 hr of the initial pST treatment.

Animals↗
PubMed1998

Sex as a possible source of group inequivalence in Lovaas (1987)

The possibility of differential sex proportions as a confounding factor in the Lovaas (1987) study is raised in this paper. It is argued that the chi-square analysis reported in the original study was inadequate and that the appropriate comparison should be made not between the experimental group and primary control group (Control Group 1) utilizing expected cell frequencies estimated from sample data, but between these two groups using population data to estimate expected cell frequencies. Implications of this interpretation are discussed.

Autistic Disorder↗
PubMed1998

Bone mineral density and composition in rat pregnancy: effects of streptozotocin-induced diabetes mellitus and insulin replacement.

A disturbed calcium homeostasis characterizes diabetic pregnancy. This study documents changes in bone mineral composition in diabetic pregnant rats and examines the effect of insulin replacement. Control pregnant (CP), diabetic pregnant (DP) and insulin-treated DP (DPi) rats were assessed for femoral calcium and magnesium content, bone mineral density (BMD) and the ratio of hypertrophic to maturing and proliferative cells in the femoral growth plate. DP rats showed a significantly (P < 0.01) lower body weight, femoral weight and length than CP rats. Femoral calcium and magnesium content was also significantly (P < 0.05) lower in DP rats, as was ash weight. When calcium and magnesium were normalized for ash weight no significant differences were apparent. A significantly (P < 0.05) lower total BMD at the distal femur was seen in DP rats. This comprised a significantly (P < 0.01) lower trabecular BMD with no significant change in cortical BMD. A significantly (P < 0.05) higher ratio of hypertrophic to maturing and proliferative cells of the femoral growth plate was evident in DP animals. DPi rats showed normal blood glucose concentrations and femoral growth plate histology. DPi rats also showed normal femoral weight and length but only partially restored femoral ash weight and mineral content. Insulin failed to normalize total or trabecular BMD. Diabetes mellitus clearly has a marked effect on bone growth and mineral content in pregnancy which may be relevant to overall calcium homeostasis. The lower bone growth, bone calcium content and trabecular BMD may be unfortunate consequences of the marked hypercalciuria reported elsewhere in diabetes and may serve to maintain normocalcaemia in the disease.

Animals↗
PubMed1998

Site of catecholamine modulation of feto-maternal electric potential difference in the pig.

Feto-maternal vascular (PD(F-M)) and amniotic maternal (PD(A-M)) potential differences were measured simultaneously on seven occasions in six conscious pigs of 100-106 days gestation. Resting values of PD(F-M) and PD(A-M) were not significantly different although the range was wide. Fetal intravascular injection of 20 microg adrenaline, but not of saline, was associated with a prompt reversible change, of equal magnitude, in both PD(F-M) and PD(A-M). In some experiments polarity was reversed. Feto-amniotic potential difference did not change. There was no change in fetal plasma K+ and Na+ concentrations. Because of the simultaneous and equal alterations in PD(F-M) and PD(A-M) following adrenaline and the anatomical configuration of the pig conceptus, we conclude that the catecholamine modifiable component of PD(F-M) is generated by electrogenesis in the pig placenta, probably by its chorionic (trophoblastic) cell layer.

Animals↗
PubMed1998

The lysine requirement of lactating primiparous sows.

We conducted an experiment with 289 primiparous sows to evaluate the effect of lysine intake on lactation and subsequent reproductive performance. Sows were randomly allotted to one of five experimental corn-soybean meal lactation diets. The first four diets contained incremental levels of apparently digestible lysine (.67, .86, 1.06, and 1.25%) and provided digestible lysine intakes of 27, 34, 41, and 48 g/d. All lysine was derived from intact protein sources. Synthetic valine, threonine, and methionine were used to maintain ratios to lysine that were equal to those of the .67% lysine diet. The fifth diet contained 1.06% digestible lysine and provided 43 g/d digestible lysine, but no additional synthetic amino acids were added. The average lactation length in this study was 16.9 +/- .2 d. Lysine intake during lactation did not affect number of pigs weaned, litter growth rate, sow backfat loss, or weaning to mating interval. Sow weight loss and loin eye area loss decreased quadratically (P < .05) with increasing lysine intake. These were minimized at 45 and 48 g/d digestible lysine, respectively. Removing synthetic amino acids from the 1.06% digestible lysine diet resulted in an increased litter growth rate (1.98 vs 2.15 kg/d, P < .05). Increasing dietary lysine intake while maintaining amino acid ratios to lysine for valine, threonine, and total sulfur amino acids during the first lactation resulted in a linear (P < .05) decrease in second litter total born. However, removal of synthetic amino acids from the 1.06% digestible lysine diet resulted in an increased second litter total born (12.9 vs 11.2, P < .05), which tended to be higher compared with the .67% digestible lysine treatment (12.9 vs 11.7, P = .13). The results suggest that primiparous sows are able to mobilize sufficient body reserves to maintain a high level of milk production at low levels of lysine intake during a 17-d lactation. Higher levels (45 to 48 g/d) of digestible lysine are required to minimize body protein loss. The source or composition of amino acids in the lactation diet may have an effect on second litter size.

Amino Acids↗
PubMed1998

The use of synthetic lysine in the diet of lactating sows.

We conducted an experiment to determine the proportion of the lysine requirement of lactating sows that can be met using L-lysine x HCl. A total of 247 Pig Improvement Company (PIC) sows (parity one to four) were randomly allotted to one of five experimental diets containing .79% apparently digestible lysine. The first four diets contained 0, .075, .150, and .225% L-lysine x HCl replacing the intact lysine, primarily derived from soybean meal. Dietary crude protein was reduced from 17.9 to 16.9, 15.8, and 14.8% respectively. The fifth diet contained .174% L-lysine x HCl (15.5% CP) with added synthetic methionine, threonine, and tryptophan to restore the ratios of these amino acids to lysine to those in the control diet with no synthetic amino acids. The average lactation length was 15.7 +/- .3 d. Diet did not affect ADFI, sow backfat loss, sow loin eye area loss, or weaning-to-mating interval. Sows consumed an average of 4.6 kg/d and were provided 36 g/d of digestible lysine. Replacing soybean meal with increasing levels of L-lysine x HCl did not affect sow weight change. The number of pigs weaned decreased and preweaning mortality increased linearly (P = .08) with increasing levels of L-lysine x HCl. Litters from sows fed the .174% L-lysine x HCl with added methionine, threonine, and tryptophan grew slower and had a higher mortality rate than litters from sows fed no synthetic amino acids (P < .05). The addition of synthetic methionine, threonine, and tryptophan to the .174% L-lysine x HCl diet did not improve litter growth rate, but it did increase preweaning mortality (P = .05) and decrease the number of pigs weaned (P = .06) compared to the .15% L-lysine x HCl with no additional synthetic amino acids. These additions also resulted in an increased sow weight loss (P = .10). These results suggest that when more than .075% L-lysine x HCl is used to meet the lysine requirement preweaning mortality is increased and the number of pigs weaned is decreased. Supplementation with methionine, threonine, and tryptophan failed to ameliorate the negative response associated with L-lysine x HCl, which suggests that other amino acids may be limiting.

Animal Feed↗