Biomedical subjects

D C Mahan

Publications and source records attributed to D C Mahan.

At least 73 records · Page 4Linked to original sources

PubMed1992

Efficacy of dietary D-alpha-tocopherol and DL-alpha-tocopheryl acetate for weanling pigs.

A 2 x 3 factorial experiment in a randomized complete block design was conducted using a total of 180 weanling pigs in five replicates. The study evaluated the efficacy of two dietary vitamin E sources (D-alpha-tocopherol, DL-alpha-tocopheryl acetate) added at three dietary levels (16, 48, 96 IU/kg) during a 35-d postweaning trial. Pigs within each treatment were fed two similarly fortified vitamin E diets in sequence; the first contained 40% milk products and was fed to 14 d, and the second contained 20% milk product and 5% fat and was provided from 15 to 35 d postweaning. Five pigs per pen per replicate were bled weekly for serum analysis of alpha-tocopherol, Se, cholesterol, triglyceride, and glutathione peroxidase (GSH-Px) activity. At the end of the trial, one pig per pen was randomly selected and killed with liver, loin, lung, and heart excised and frozen for tocopherol analysis. Postweaning gains, feed intakes, and efficiencies were similar between the two vitamin E sources and at the various dietary levels. Serum tocopherol concentrations were consistently higher when D-alpha-tocopherol was provided. Vitamin E sources and levels had no effect nor did they influence weekly serum Se, cholesterol, or triglyceride concentrations or GSH-Px activity. A serum and tissue interaction (P less than .05) response occurred between dietary vitamin E source x level with alpha-tocopherol concentrations increasing linearly (P less than .01) as dietary vitamin E level increased, but at a higher rate when D-alpha-tocopherol than when DL-alpha-tocopheryl acetate as fed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Efficacy of dietary sodium selenite and calcium selenite provided in the diet at approved, marginally toxic, and toxic levels to growing swine.

A 2 x 3 factorial experiment conducted in three replicates of a randomized complete block design compared the effects of calcium selenite and sodium selenite at three different levels of Se (.3, 5, or 15 ppm) in the diets of growing swine on performance and tissue Se concentrations. Ninety pigs averaging 12.5 kg of BW were given ad libitum access to corn-soybean meal diets fortified with one of the treatment Se sources and dietary levels for a 35-d experimental period. Growth and feed intake were similar in pigs fed .3 and 5 ppm of Se but were lower (P less than .01) in those fed 15 ppm from either Se source. Serum Se increased (P less than .01) as dietary Se level increased with no difference between Se sources at each dietary Se level. Liver, kidney, and longissimus muscle Se concentrations increased (P less than .01) as the dietary level of Se increased and were similar when either Se sources was provided. These results indicate that calcium selenite was as effective as sodium selenite using the measurement criteria of growth, serum, and tissue Se concentrations and glutathione peroxidase activities of growing swine when fed at approved, marginally toxic, and toxic dietary Se levels.

Animal Feed↗

PubMed1991

Effect of pig weaning weight and associated nursery feeding programs on subsequent performance to 105 kilograms body weight.

An experiment using a total of 210 crossbred pigs from two farrowing groups evaluated the effects of three weaning weights and their associative starter feeding program on subsequent postweaning performance to 105 kg BW. One group of pigs nursed their dams in outside heated hutches (Trial 1), and a second group was raised in a centrally heated farrowing house (Trial II). The three pig weaning weight groups ranged in weight from 1) 4.1 to 5.0 kg, 2) 5.5 to 6.8 kg, and 3) 7.3 to 8.6 kg. Pigs in Group 1 were fed a high nutrient dense diet (HNDD) for a 2-wk period followed by a corn-soybean meal-dried whey (C-SBM-DW) and then a corn-soybean meal (C-SBM) diet, each for a 2-wk period. Group 2 was fed the same diet sequence except that HNDD was provided for 1 wk, whereas Group 3 was provided only the C-SBM-DW and the C-SBM diets each for 2 wk, consecutively. At the end of the nursery period, pigs were fed C-SBM diet formulations to 105 kg BW. Pigs of Trial I averaged 5.2 d older at weaning than those raised in the central farrowing house, but only a 1.5-d difference existed between light- and heavy-weight groups in both trials. Gains and feed intakes for the three weaning groups were higher as weaning weight increased during both the nursery and the growing-finishing period. There did not seem to be a compensatory growth response for lighter-weight weanling pigs even though they had been fed starter diets containing milk products. Consequently, fewer days (approximately 15) were required for the heavier-weight weanling pig group to reach a final weight of 105 kg than for the light-weight group. The medium-weight group required an intermediate number of days to reach 105 kg.

Animal Feed↗

PubMed1991

Efficacy of initial postweaning diet and supplemental coconut oil or soybean oil for weanling swine.

Two experiments involving a total of 581 crossbred pigs weaned at 23 +/- 2 d of age evaluated 1) the efficacy of two diets that contained milk products during the initial 14 d postweaning and 2) the effect of coconut oil or soybean oil additions to swine starter diets. In Exp. 1, postweaning performance responses of pigs fed a control corn-soybean meal-dried whey (C-SBM-DW) diet without added fat were compared with those of pigs consuming diets that contained 3, 6, or 9% levels of coconut oil or degummed soybean oil. The results demonstrated no beneficial weight gain, feed intake, or gain-to-feed ratio response during the initial 14 d postweaning to either dietary oil source. From 15 to 35 d, gains increased to the 6% added fat level, but there was no effect on feed intake when the gain-to-feed ratio was improved to the 9% fat level. In Exp. 2, two diets containing milk products were fed during the initial 14-d postweaning period. The first diet contained corn, soybean meal, dried whey, dried skim milk, and fishmeal (high nutrient dense diet, HNDD), and the second was a C-SBM diet with 25% dried whey. During the period from 15 to 35 d, diets contained no added fat or a 6% level of coconut oil, soybean oil, or the 1:1 combination of each at 3%. The results demonstrated that for the postweaning period from 0 to 14 d pigs fed the HNDD had higher gains (P less than .01), feed intakes (P less than .01), and gain-to-feed ratios (P less than .01) than pigs fed the C-SBM-DW diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1991

Growth performance of weanling pigs fed corn-soybean meal diets with or without dried whey at various L-lysine.HCl levels.

A total of 490 crossbred weanling pigs were used to evaluate the responses to and the subsequent interaction between dietary dried whey and crystalline L-lysine.HCl on postweanling growth and feed efficiency at two periods postweaning. The experiment was conducted as a 2 x 5 factorial arrangement of treatments in a randomized complete block design to evaluate two levels of edible-grade dried whey (0 or 25%) and five dietary lysine levels ranging from 1.10 to 1.50% in .10% increments using a corn-soybean meal mixture as the basal feedstuff. Pigs were allotted by weight, litter, and sex to seven replicates at weaning (23 +/- 2 d) and fed their treatment diets for a 35-d period. Daily gain and feed intake were greater (P less than .01) for both the 0- to 21- and the 22- to 35-d periods when dried whey was fed; the relative magnitude of the response to dried whey was greatest during the initial 21-d period. Growth responses during the 0- to 21-d period were, however, independent of dietary lysine level, suggesting that dietary lysine at a level of 1.10% is not the limiting nutrient in a corn-soybean meal diet or a corn-soybean meal diet with dried whey. From 22 to 35 d postweaning a linear growth response to lysine level occurred when the dried whey diet was fed, but no response was detected when lysine was added to the corn-soybean diet, resulting in a diet x lysine level interaction (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1991

Assessment of the influence of dietary vitamin E on sows and offspring in three parities: reproductive performance, tissue tocopherol, and effects on progeny.

Sixty crossbred (Yorkshire-Hampshire X Duroc) gilts were fed one of four corn-soybean meal diets fortified with .3 ppm Se and 0, 16, 33, or 66 IU of DL-alpha-tocopheryl acetate/kg. The study was conducted over a three-parity period to evaluate sow reproductive performance and the vitamin E tissue status of both sows and progeny at various time periods postcoitum and(or) postpartum. The basal diet averaged 8.4 mg of alpha-tocopherol/kg and .38 ppm of Se. Although litter size at birth was lowest (P less than .15) when sows were fed the basal diet, a higher incidence of agalactia when sows were fed the lower dietary vitamin E levels resulted in an increased (P less than .05) litter size at 7 d postpartum as dietary vitamin E increased. Sow serum alpha-tocopherol increased (P less than .01) at each measurement period as dietary vitamin E level increased. Colostrum and milk alpha-tocopherol concentrations increased (P less than .01) as dietary vitamin E level increased, and colostrum values were three to five times higher than at later milks. Colostrum alpha-tocopherol declined by parity from sows fed less than or equal to 16 IU/kg but was similar at each parity for sows fed greater than or equal to 33 IU/kg, resulting in a dietary vitamin E x parity interaction (P less than .01). The Se content of sow milk declined with parity but was not affected by dietary vitamin E level. Sow liver tocopherol at weaning (28 d postpartum) increased (P less than .01) as dietary vitamin E increased and increased with parity (P less than .05). Pig serum and liver alpha-tocopherol concentrations were elevated at birth and 7 and 28 d of age as sow dietary level of vitamin E increased. Upon weaning, pigs were fed a torula yeast-dextrose diet that contained 3.0 mg of alpha-tocopherol/kg and .32 ppm Se for a 28-d postweaning period. Liver and serum alpha-tocopherol concentrations declined during the postweaning period. Evidence of the vitamin E deficiency occurred at 28 d postweaning in the progeny from sows fed the basal diet or 16 IU of vitamin E; the incidence was more prevalent in the pigs from Parities II and III. These results suggest that a supplemental level of 16 IU of vitamin E/kg of diet was inadequate for the reproducing sow; higher levels are justified, particularly when females are retained in the herd for several parities.

Animal Feed↗

PubMed1990

Isolation, characterization, and developmental expression of pig intestinal fatty acid-binding proteins.

The goal of this study was to characterize and quantify intestinal fatty acid-binding proteins of the pig. Small intestinal mucosa from 13-19 kg pigs was homogenized and centrifuged to obtain cytosol. Isolation of fatty acid-binding proteins from delipidated cytosol was achieved using molecular sieve, oleic acid affinity, and ion exchange chromatography. Fatty acid-binding protein isolation was monitored using a fatty-acid binding assay in conjunction with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. Antisera to rat liver-fatty acid-binding protein cross reacted with an isolated intestinal fatty acid-binding protein of Mr = 13,000, whereas antisera to rat intestine-fatty acid-binding protein was not cross reactive with isolated pig intestinal proteins. These experiments identify a pig intestinal fatty acid-binding protein that exhibits strong immunochemical similarity to rat liver-fatty acid-binding protein. Cytosol prepared from intestinal mucosa of pigs at -4, 2, 4, 7, 15, 22, 28, and 35 d of age was assayed for fatty acid-binding protein activity. Preweaning fatty acid-binding protein activity in cytosol was maximal at 7 days of age when expressed as total jejunal fatty acid binding per kilogram bodyweight, intestinal or mucosal weight or milligram total protein. After weaning (21 d), fatty acid-binding protein activities declined to 28 days, but increased again by 35 days. Total soluble fatty acid-binding protein activity in pig intestine is regulated during postnatal development and this may account in part for the altered intestinal absorption of lipids observed in young pigs at weaning.

Journal Article↗

PubMed1990

Stimulation by colostrum or mature milk of gastrointestinal tissue development in newborn pigs.

Porcine colostrum and milk were orally administered to newborn pigs to evaluate their gastrointestinal growth-promoting activity. Five piglets per treatment group were gavage-fed 5% lactose (L), defatted colostrum (C) or defatted mature milk (d 16 of lactation) (M) at 3-h intervals over a 24-h period. Colostrum and milk were administered on equivalent dry matter basis and all piglets received 1 mCi of [3H]thymidine per kg BW at the onset of feeding. Small intestines of C- and M-fed pigs were 1.6-and 1.3-fold, respectively, the weight of small intestines of those fed L (P less than .01). Total DNA content of intact small intestines were not different among groups; however, cpm [3H]thymidine/mg intestinal DNA of C and M piglets exceeded (P less than .05) that for L piglets. DNA content and cpm [3H]thymidine of intestinal mucosa did not differ among groups. Total protein in the intestines and intestinal mucosa of C pigs exceeded (P less than .01) that for L and M pigs. Total RNA in the small intestine and intestinal mucosa were similar for C and M groups but less (P less than .01) for L piglets. Stomach and pancreas weights among all pigs were similar, although C and M pigs exceeded L pigs in stomach (P less than .01) and pancreas (P less than .01) RNA content. In contrast, no differences in stomach DNA, protein and cpm [3H]thymidine or in pancreatic DNA, protein and cpm [3H]thymidine were detected. SDS-polyacrylamide gel electrophoresis was used to identify qualitative and quantitative differences in the protein compositions of porcine colostrum and mature milk.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Effect of weaning, week postweaning and diet composition on pancreatic and small intestinal luminal lipase response in young swine.

The effects of weaning, week postweaning and diet composition on concentration of lipase in the pancreas and small intestinal lumen were investigated in weanling swine. In Exp. 1, lipase levels were evaluated in suckling pigs from 2 to 35 d of age and in pigs weaned at 21 or 35 d of age. Pigs weaned at 21 d of age were fed a corn-soybean meal diet with lipase levels measured from 3 to 28 d postweaning. Pancreas weights increased during the suckling period; they were lowered at 3 d postweaning and were lower at 7 d postweaning than in suckling pigs but increased linearly from 3 to 28 d postweaning. Lipase level per unit wet tissue and total pancreatic levels increased from 2 to 35 d of age in suckling pigs (P less than .01). Weaning at 21 d of age resulted in a decline (P less than .05) in lipase levels in the pancreas at 3 and 7 d postweaning, but the levels subsequently tended to increase between 7 and 28 d postweaning. Whereas relative lipase levels in the intestinal lumen increased from 2 to 35 d of age in suckling pigs, total luminal enzyme did not decline upon weaning when pigs were weaned at either 21 or 35 d of age. Total luminal lipase per unit empty body increased linearly (P less than .01) each week postweaning. In Exp. 2, a 2 X 2 factorial arrangement of corn oil (0 or 6%) and dried whey (0 or 25%) was used to evaluate digestive lipase levels in pigs weaned at 21 d of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1990

Mineral nutrition of the sow: a review.

The sow varies greatly in her mineral requirements, which largely reflects the nutritional demands during different phases of her reproductive cycle. Minerals are required for conceptus product formation, mammary secretions, and growth and maintenance. Although the sow's mineral requirements are highest during late gestation and lactation, those that are supplied from the diet and tissue reserves both contribute in meeting these nutritional needs. The sow is fairly resilient to borderline mineral insults, but longevity in the herd may be compromised under these conditions. Specific mineral deficiencies vary, but the reproducing sow will deplete the pool of tissue minerals before litter size, congenital abnormalities of developing fetuses or milk mineral composition are affected. Inadequate mineral supplies may prolong the duration of parturition, increase the number of stillbirths and result in a higher occurrence of skeletal problems. Tissue mineral reserves can be increased in various tissues with higher dietary fortification, but subsequent mineral availability from various pools differ. Because feed intake during lactation is low, daily mineral intake during lactation often is below NRC (1988) requirements.

Animal Nutritional Physiological Phenomena↗

PubMed1990

Evaluation of various extracted vegetable oils, roasted soybeans, medium-chain triglyceride and an animal-vegetable fat blend for postweaning swine.

A total of 280 crossbred pigs weaned at 21 d of age and weighing approximately 6 kg were utilized in five replicates to evaluate pig growth responses when fed a basal diet or one of several dietary lipid sources during a 4-wk postweaning period. A basal corn-soybean meal-corn starch-dried whey diet was compared with diets supplemented at a 7.75% level with one of the following lipid sources: corn oil, coconut oil, soybean oil, medium-chain triglyceride (MCT) or an animal-vegetable blend. A sixth treatment evaluated a roasted soybean diet formulated to an energy:lysine level equivalent to that of the fat-supplemented diets. In Exp. II, 36 crossbred weanling barrows were used to determine apparent fat and N digestibilities when soybean oil, roasted soybean, coconut oil or the MCT-supplemented diets were fed. Although pigs fed coconut oil grew somewhat faster, fat inclusion generally did not increase pig growth rate or result in lowered feed intake during the initial weeks postweaning; during the latter portion of the starter phase the addition of dietary fat resulted in a higher growth rate but feed intake was unaffected, resulting in an overall improvement in feed-to-gain ratio (P less than .05) for all but the roasted soybean diet. Pigs fed coconut oil had higher serum triglyceride and lower serum urea concentrations than did pigs fed diets containing most other lipid sources. Pigs fed MCT and coconut oil diets had a higher (P less than .01) apparent fat digestibility during the initial 2 wk postweaning than pigs fed soybean oil or roasted soybean diets. Pigs fed MCT and roasted soybeans had poorest growth rates; apparent fat and N digestibilities were lowest (P less than .05) for the roasted soybean diet.

Animal Feed↗

PubMed1989

Effect of group size and feeding regimen on nutrient digestibility studies with weanling pigs.

An experiment was conducted to determine the effects of feeding regimen and group size on nutrient (N, Lipid, Ca, P) balance measurements with weanling swine. Treatments imposed were 1) one pig pair-fed to 90% of treatment 3, 2) three pigs pair-fed to 90% of treatment 3 and 3) three pigs with ad libitum access to their diet. A total of 28 barrows weaned at 21 d of age (initial BW 5.9 kg) were allotted by weight and litter in a randomized complete block design with repeated measurements over time to the three treatments in four replicates. The pigs were placed in .6-m x 1.13-m stainless steel metabolism crates and fed the same experimental diet for an initial 4-d adjustment period. This was followed by a 5-d collection of urine and feces with a 2-d interval between collection periods each week of a 4-wk postweaning period. When feed was restricted, N intake, urine N, fecal N and retained N were similar whether pigs were fed as singles or in groups of three. Individually fed pigs had a higher urinary Ca but lower urinary P compared with those fed in groups of three. Lipid and P retention values were similar for individual and group-penned, restricted-fed animals. Pigs provided ad libitum access to feed had greater weight gains and nutrient intakes, excretions (urine, fecal) and retentions (P less than .01) than pigs that were limit-fed. Similar responses among treatments occurred each week of the 4-wk trial. These results suggest that effective weekly balance data can be collected each week sequentially with 21-d weanling pigs penned in groups and allowed to consume feed ad libitum, a situation more similar to natural nursery conditions.

Animals↗

PubMed1988

Effect of age, weaning and postweaning diet on small intestinal growth and jejunal morphology in young swine.

The effect of age, weaning and postweaning diet on small intestinal growth and morphology were investigated in young swine. Small intestine weight and villus height, measured at the midpoint of the small intestine (i.e., jejunum), were determined in suckling and weaned pigs. Scanning electron microscopy was performed on jejunal specimens from suckling pigs killed at 2, 10, 21, 28 and 35 d of age and in 21-d and 35-d weaned pigs at various ages postweaning. A 2 X 2 factorial arrangement of postweaning diets also was used to investigate jejunal morphological measurements in a 21-d-old weanling pig group. These dietary treatments evaluated the effects of 0 or 25% added dried whey and 0 or 6% added corn oil. The morphology results demonstrated that jejunal villus height declined during the suckling period, with a marked reduction at 3 and 7 d postweaning for both 21-d-old and 35-d-old weaned pigs. Transmission electron microscopy also demonstrated long, uniform microvilli on the jejunal villi in suckling pigs at 2 and 21 d, with markedly reduced lengths upon weaning. Jejunal villi were shorter in weaned compared with suckling pigs at the same approximate chronological age. Scanning electron microscopy in suckling pigs at 2 and 10 d of age demonstrated long, thin, fingerlike villi with subsequently reduced heights and larger diameters by 35 d of age. At weaning, villi were in close apposition, resulting in an overall smoother villus luminal surface. Villus height subsequently increased by 14 d postweaning, coinciding with the appearance of morphologically tongue-shaped villi. Starter diet composition initially did not influence the villus height reduction response postweaning. Dietary corn oil addition was subsequently associated with shortened villus length (P less than .05) during the starter phase.

Aging↗

PubMed1988

Weekly digestibilities of diets supplemented with corn oil, lard or tallow by weanling swine.

Two experiments were conducted to evaluate supplementation of diets with 8% corn oil, lard or tallow. In Exp. 1, 36 barrows weaned at 21 d of age were used to evaluate the effects of these three diets on digestibilities of fat and dry matter and subsequent N retentions from wk 1 to 4 postweaning. In Exp. 2, 147 weanling pigs in six replicates were used to evaluate weekly growth and feed performance measurements when fed these same diets for a 4-wk postweaning period. A large quantity of fat was absorbed (P less than .01) during wk 1 postweaning by pigs fed the corn oil diet, with the quantity absorbed similar for the three sources of fat from wk 2 to 4. Diets with corn oil had a higher apparent fat digestibility than diets supplemented with lard or tallow during each week postweaning (P less than .05). Apparent digestibility of fat increased (P less than .01) for each fat source each week postweaning but appeared to reach a plateau by wk 3 postweaning. Differences in apparent digestibility of fat between fat sources narrowed from wk 1 to wk 4, with digestibility of corn oil increasing from 79 to 89% and of animal fat sources increasing from 67 to 84%. Apparent digestibility of dry matter tended (P less than .10) to be highest when corn oil was provided during the initial 2-wk postweaning period. Although N retention was highest during wk 1 postweaning when the corn oil was fed, this response was attributed to the higher feed intakes of pigs fed this diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1988

Effects of dietary dried whey and corn oil on weanling pig performance, fat digestibility and nitrogen utilization.

Two experiments were conducted to evaluate the effects and interactions of dietary levels of corn oil (0 vs 6%) and dried whey (0 vs 25%) on performance of young pigs during a 4-wk postweaning period. The first experiment, conducted in five replicates as a 2 x 2 factorial in a randomized block design, evaluated gain and feed intakes of 172 pigs weaned at 21 d of age. Pigs were bled at weekly intervals, and samples were assayed for serum triglyceride and urea concentrations. In a second experiment, 36 barrows in three replicates were used to evaluate the same treatments on apparent digestibility and absorption of fat and N retention during each week of a 4-wk postweaning period. The dietary inclusion of dried whey resulted in greater gains and feed intakes and reduced feed-to-gain ratios during each week of the postweaning period, with the largest relative improvement occurring during wk 1. Supplemental corn oil did not enhance pig gains the first 3 wk postweaning, but response improved by wk 4. Feed intakes were slightly (P less than .10) lower when corn oil was provided. The inclusion of corn oil resulted in an improved feed-to-gain ratio (P less than .01), particularly evident during wk 3 and 4 postweaning. Neither gain nor feed utilization were improved by added corn oil during the initial 2-wk postweaning period regardless of dried whey addition. Apparent digestibilities of fat were unaffected at each weekly interval by dietary dried whey inclusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Effect of dietary calcium and phosphorus level sequences on performance, structural soundness and bone characteristics of growing-finishing swine.

The effects of feeding various dietary Ca:P level sequences on gain and feed efficiency, leg structural soundness and bone indices of growing-finishing swine were evaluated as an incomplete 3 X 3 factorial arrangement of treatments in a split-plot design. A total of 664 pigs were fed one of three total dietary Ca:P levels (.52:.40, .65:.50, .80:.60%) from 19-kg to 56-kg body weights followed by one of three Ca:P levels (.45:.32, .52:.40, .65:.50%) to market weight. The .80:.60% and .65:.50% Ca:P mineral sequence was not evaluated. Diets were formulated to 14.5% crude protein using a corn-soybean meal mixture with proportions of dicalcium phosphate and limestone altered to attain the desired dietary Ca:P levels. Maximum gains occurred at the .65:.50% and .52:.40% Ca:P level during the grower (P less than .01) and finisher (P less than .01) periods, respectively. No grower X finisher phase pig gain or feed intake interaction resulted, providing evidence of no carry-over response on these measurements from the grower to the finisher period. Serum P concentration increased and plateaued at the same dietary Ca:P level, as did rate of gain at both 56-kg and 95-kg body weights. Leg soundness subjectively evaluated at 56-kg and 95-kg body weights revealed no effect of dietary Ca:P level on soundness scores at 56 kg, but at 95-kg body weight, the interaction between grower and finisher diets was significant. Percentage bone ash of the humerus, shaft thickness and bending moment of the femur increased as dietary Ca:P level increased at both 56-kg and 95-kg body weights.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

In vitro growth-promoting activity of porcine mammary secretions: initial characterization and relationship to known peptide growth factors.

We have examined the in vitro growth-promoting properties and growth factor content of porcine mammary secretions. Defatted, porcine colostrum stimulated the proliferation of fibroblast and epithelial-like cell lines of diverse species origins in serum-free medium and cellular DNA synthesis (4- to 119-fold) as monitored by uptake of 3H-thymidine into DNA of quiescent cells in culture. Porcine milk, although mitogenic, had reduced activity when compared with colostrum on an equivalent-volume basis. Furthermore, the relative mitogenic activity of milk, although still detectable at 3 wk, continued to decline with length of the lactation period. Fractionation of pig colostrum on gel-filtration columns revealed multiple peaks of (AKR-2B) fibroblast mitogenic activity (208, 66 and 4.6 kdaltons) and a heterogenous profile of epithelial cell mitogenicity. Polyclonal antibodies (IgG) specific for murine epidermal growth factor (EGF; the major mitogen in human and murine milk) or human platelet-derived growth factor (PDGF) did not inhibit the mitogenic activity of pig colostrum or milk, demonstrating lack of antigenic relatedness between the contributing porcine factors and mEGF or hPDGF. Also, we were unable to demonstrate similarity of the small Mr colostral factor with EGF by use of EGF radioreceptor assay. These results identify porcine colostrum and milk as sources of potentially important in vitro growth-promoting factors. The enhanced expression of these factors in early mammary secretions suggests their possible in vivo involvement in mammary and neonatal tissue growth processes.

Animals↗

PubMed1986

Biological characteristics for assessing low phosphorus intake in finishing swine.

Three replicates of a randomized complete-block design in a 3 x 3 factorial arrangement of treatments involving 141 pigs were conducted to evaluate the effect of low P intake on various response criteria in swine from 65 to 95 kg body weight. Total dietary P levels of .09, .21 and .31% were each fed in a Ca:P ratio of 1.1, 1.5:1 or 2:1 for a 35-d experimental period. The basal diet was formulated using corn starch, dextrin and a soy protein concentrate with monosodium phosphate and limestone supplying desired treatment levels of Ca and P. Blood and bones were collected for mineral analysis. Gain and feed performance responses were not affected by Ca:P ration or dietary P level for the 35-d period. Serum inorganic P concentrations declined as Ca:P ratio increased, but increased as dietary P increased. Serum alkaline phosphatase activity increased with higher Ca:P ratios, and decreased as dietary P level increased. Percent bone ash was not influenced by Ca:P ratio, but increased as dietary P level increased. Bone-bending moment was influenced by Ca:P ratio, and increased linearly as dietary P increased. Dietary P level resulted in a linear increase in total bone and its ash component weight, and in the accretion of the ash and organic matrix component. These data suggest that between 65 to 95 kg body weight, percent bone ash was affected by dietary P level, while bone-bending moment, bone component weights, their accretion, both dietary p level and Ca:P ratio.

Animals↗