Comparative effects of organic and inorganic selenium on selenium transfer from sows to nursing pigs

To investigate the effects of supplemental Se on the transfer of Se to nursing pigs when sows are fed diets containing a Se level above the NRC recommendation (0.15 ppm), sows were fed diets containing no supplemental Se or supplemental (0.3 ppm) Se from sodium selenite or Se yeast. A nonSe-fortified corn-soybean meal basal diet with a high endogenous Se content served as the negative control (0.20 to 0.23 ppm Se). Fifty-two sows were fed diets from 60 d prepartum until 14 d of lactation. Six sows per treatment were bled at 60 and 30 d prepartum, at farrowing, and at 14 d postpartum to measure serum Se concentrations. Colostrum was collected within 12 h postpartum, and milk was collected at 14 d of lactation. Blood was obtained from 3 pigs each from 12 litters per treatment at birth and at weaning (d 14), and pooled serum was analyzed for Se and immunoglobulin G concentrations and glutathione peroxidase activity. Regardless of treatment, serum Se in sows declined throughout gestation and gradually increased during lactation. Sows fed Se yeast tended (P < 0.06) to have greater serum Se at farrowing than sows fed unsupplemented diets. Colostrum and milk (d 14) Se concentrations increased (P < 0.01) when sows were fed Se from yeast but not from sodium selenite. At birth, serum Se was increased (P < 0.01) for pigs whose dams were fed Se yeast compared with pigs from sows fed the basal diet. At 14 d of age, there was no difference in serum Se concentration of pigs from dams fed any of the treatments. Pig serum immunoglobulin G concentrations and glutathione peroxidase-1 activity were unaffected by dietary Se source. Supplementation of gestating and lactating sow diets with Se (0.3 ppm) from an organic or inorganic source reduced the number of stillbirths per litter. However, only pigs born to sows fed organic Se (Se yeast) had greater serum Se at birth. Organic Se increased Se concentration of colostrum and 14-d milk to a greater degree than inorganic Se.     

Efficacy of dietary selenium sources on growth and carcass characteristics of growing-finishing pigs fed diets containing high endogenous selenium

A study was conducted to determine the efficacy of organic (Se-yeast, SelenoSource AF, Diamond V Mills Inc., Cedar Rapids, IA) and inorganic sources of Se on growth performance, tissue Se accretion, and carcass characteristics of growing-finishing pigs fed diets with high endogenous Se content. A total of 180 pigs at 34.4 +/- 0.06 kg of BW were allotted to 1 of 5 dietary treatments: a negative control without added Se (NC); 3 treatment diets with 0.1, 0.2, or 0.3 mg/kg of added Se from an organic source; and a diet with 0.3 mg/kg of added Se as sodium selenite. Each treatment had 6 pens, with 6 pigs per pen-replicate. Experimental diets were changed twice at 66.1 +/- 0.5 kg and 99.0 +/- 0.9 kg of BW, and were fed until the pigs reached market weight. Growth performance was measured at the end of each phase. Upon reaching 129.9 +/- 1.4 kg of BW, the pigs were transported to a local abattoir (Seaboard Foods, Guymon, OK), where carcass, loin, and liver samples were obtained. Hair and blood samples were obtained at the beginning and end of the study for Se analysis. Growth performance did not differ (P > 0.05) among treatments. Percent drip loss of the NC pigs was greater (2.41 vs. 1.75, P = 0.011) compared with pigs supplemented with Se. Pigs fed diets with added Se had greater Se concentrations in the liver (0.397 vs. 0.323 ppm, P = 0.015), loin (0.236 vs. 0.132 ppm, P < 0.001), serum (0.087 vs. 0.062 ppm, P = 0.047), and hair (0.377 vs. 0.247 ppm, P = 0.003) compared with the NC pigs. Percentage drip loss was linearly reduced [percent drip loss = 2.305 - (2.398 x Se), r2 = 0.29, P = 0.007] as dietary organic Se concentration increased. The Se concentration (ppm) in the liver [liver Se = 0.323 + (0.291 x Se), r2 = 0.33, P = 0.003], loin [loin Se = 0.122 + (0.511 x Se), r2 = 0.57, P < 0.001], serum [serum Se = 0.060 + (0.113 x Se), r2 = 0.33, P = 0.004] and hair [hair Se = 0.237 + (0.638 x Se), r2 = 0.56, P < 0.001] increased linearly as dietary organic Se concentration increased. Slope ratio analysis indicated that the relative bioavailability of organic Se for percent drip loss and loin and hair Se response was 306, 192, and 197% of that for inorganic Se, respectively. The results of the study show a potential advantage of organic Se supplementation in reducing drip loss even when the basal diet contains an endogenously high Se concentration of 0.181 ppm.     

Long-term effects of dietary organic and inorganic selenium sources and levels on reproducing sows and their progeny

An experiment evaluated the effects of feeding either a basal non-Se-fortified diet, two Se sources (organic or inorganic) each providing 0.15 and 0.30 ppm Se, or their combination (each providing 0.15 ppm Se) on gilt growth and sow reproductive performance. The experiment was a 2 x 2 + 2 factorial conducted in a randomized complete block design in three replicates. One hundred twenty-six crossbred gilts were started on one of the six treatment diets at 27.6 kg BW. During the grower phase, animals were bled at 30-d intervals with three gilts killed per treatment at 115 kg BW for tissue Se analysis. Fifteen gilts per treatment were bred at 8 mo of age and were continued on their treatment diets for four parities. Sow serum collected within parity was analyzed for Se and glutathione peroxidase (GSH-Px) activity. Tissue Se was determined from five 0-d-old pigs per treatment from fourth-parity sows. Three sows per treatment were killed after the fourth parity for tissue Se analysis. Similar treatment performance responses occurred from 27 to 115 kg BW. Serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased for both Se sources to 0.30 ppm Se during the grower and reproductive periods. Serum Se and GSH-Px activity decreased from 70 to 110 d postcoitum in all treatment groups, but increased at weaning (P < 0.01) in the Se-fortified groups. The number of pigs born (total, live) increased (P < 0.05) with the 0.15 ppm Se level for both Se sources. Tissue and total body Se content of 0-d-old pigs increased with Se level (P < 0.01) and also when the organic Se source (P < 0.01) was fed to the sow. When sows were fed either Se source, pig serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased at weaning. Colostrum and milk Se concentrations increased (P < 0.01) with Se level for both Se sources, but were substantially greater (P < 0.01) when sows were fed organic Se. The combination of Se sources had sow milk and tissue Se values that were similar to those of sows milk and fed 0.15 ppm organic Se. The fourth-parity sows had greater tissue Se concentrations when organic Se level was increased (P < 0.01), more so than when sows were fed inorganic Se. These results suggest that both Se sources resulted in similar sow reproductive performances at 0.15 ppm Se, but sows fed the organic Se source had a greater transfer of Se to the neonate, colostrum, milk, weaned pig, and sow tissues than sows fed inorganic Se.     

Selenium status in adult cats and dogs fed high levels of dietary inorganic and organic selenium

Cats (Felis catus) maintain greater blood Se concentrations compared with dogs (Canis familiaris) and, unlike dogs, show no signs of chronic Se toxicity (selenosis) when fed dietary organic Se (selenomethionine) concentrations of 10 μg/g DM. This study investigated the response of cats and dogs to high dietary concentrations of sodium selenite and organic Se to determine differences in metabolism between both species. In 2 consecutive studies, 18 adult cats and 18 adult dogs of with equal numbers of each sex were fed a control diet (0.6 μg Se/g DM) or the control diet supplemented to 8 to 10 μg Se/g DM from Na(2)SeO(3) or organic Se for 3 wk. All animals were fed the control diet 1 mo before the start of the study and blood samples were taken on d 0 and 21. The Se balance was assessed during the final week and a liver biopsy was obtained on the final day of the study. Measurements included plasma Se concentrations, plasma glutathione peroxidise (GPx) activities, plasma Se clearance, Se intake, and urinary Se excretion. No clinical signs of selenosis were observed in the cats or dogs, and apart from Se clearance, form of Se had no effect on any of the measurements. Apparent fecal Se absorption was greater in the dogs fed both forms of Se, while greater plasma Se concentrations were observed in the cats on both the control and supplemented diet (P = 0.034). Cats fed the supplemented diets had lower hepatic Se concentrations (P < 0.001) and excreted more Se in urine (P < 0.001) compared with dogs. Furthermore, cats fed the Na(2)SeO(3) supplement had greater Se clearance rates than dogs (P < 0.001). There was no effect of species on plasma GPx activity. We conclude that cats can tolerate greater dietary Se concentrations as they are more efficient at excreting excess Se in the urine and storing less Se in the liver.     

The feeding of ad libitum dietary protein to organic growing-finishing pigs

The effects of three dietary protein levels on growth, meat, and carcass traits were studied in organic pigs fed a three-phase diet. Assuming lysine was the first limiting amino acid, feeds were formulated to ileal digestible (ID) lysine content, with the ID lysine:crude protein ratio set at a constant of 4%. Feeds were also formulated to an isocaloric rate (net energy: 9.4 MJ/kg during the first feeding phase, 9.25 MJ/kg during the second feeding phase and 9.1 MJ/kg during the finisher phase), with a high (HP), a medium (MP) or a low (LP) protein content ranging from 20% to 14% crude protein (CP). ID lysine content of the LP and MP feed was, respectively, 80% and 90% of the ID lysine content of the HP feed. The nutrient formulation of the HP feed was similar to nutrient levels commonly used in conventional Belgian pig farming. From 20 to 40 kg liveweight, the pigs showed better feed conversion ratios, with an increasing dietary protein concentration (r(2)=0.84). This effect was not observed in the second and third phases, although a significant effect of protein concentration on voluntary feed intake in the second phase did occur (P=0.018), probably as a compensation for the lower protein concentration in the LP diet. Analysis of the carcasses showed a lower meat percentage with lower protein concentration (P<0.05), whereas influences on meat quality were limited. It was concluded that whereas during the first phase of growth, higher protein concentration leads to better performance, from the second phase onwards (45 kg), at least with isocaloric diets, a decrease in protein content (corresponding to a 10% reduction in dietary ID lysine levels compared to conventional pig fattening) may be used in organic growing-finishing pig nutrition.     

Prolonged feeding of high dietary levels of organic and inorganic selenium to gilts from 25 kg body weight through one parity

An experiment evaluated the selenosis effects from feeding high dietary Se levels of organic or inorganic Se sources to growing gilts with the dietary treatments continued through a reproductive cycle. A total of 88 gilts were allotted at 25 kg BW to two replicates in a 2 x 4 factorial arrangement in a randomized complete block design. Inorganic Se (sodium selenite) or organic (Se-enriched yeast) Se were added to diets at 0.3, 3, 7, or 10 ppm Se. At 105 kg BW, four gilts per treatment were killed and livers collected for Se analysis. At 8 mo of age, three gilts from each treatment group were bred and fed their treatment diet, with subsequent reproductive performance and selenosis effects evaluated. Serum collected at various intervals in gilts, sows, and progeny measured glutathione peroxidase activity and Se concentrations. Sow colostrum and milk was analyzed for their Se concentrations. Three pigs per treatment were killed before colostrum consumption and at weaning (14 d) and tissue collected for Se analysis. Gilt gains (P < 0.01) and feed intakes (P < 0.05) declined during the grower period as dietary Se level increased for both Se sources. Serum and liver Se concentrations increased as dietary Se level increased and was higher when organic Se was fed (P < 0.01). Sows fed dietary Se levels at > 7 ppm had lower gestation weights (P < 0.05) and lower lactation feed intakes (P < 0.05). As Se level increased, sows fed organic Se had a lower number of live pigs born (P < 0.05) and weaned fewer pigs (P < 0.05) with lower litter gains (P < 0.05) than did sows fed inorganic Se. Colostrum and milk Se concentrations increased as dietary Se levels increased particularly when organic Se was fed (P < 0.01). Neonatal and weanling pig tissue Se and serum Se concentrations increased as dietary Se level increased and when organic Se was fed, resulting in interaction responses (P < 0.01). Pigs nursing sows fed > 7 ppm inorganic Se had hoof separation and alopecia, with the severity being greater when sows were fed the inorganic Se source. These results suggest that both the organic and inorganic Se sources were toxic when fed at 7 to 10 ppm for a prolonged period, but organic Se seemed to express the selenotic effects more on reproductive performance, whereas inorganic Se was more detrimental during lactation.     

有机硒的添加效果优于无机硒

硒作为一种化学元素,是在1819年由瑞典化学家柏塞吕斯(Bercelius)发现的。几乎在140年之后,人们才清楚地认识到,它是动物营养中一种必需的元素。大量证据表明,硒在饲料原料中含量差异很大,具体取决于土壤中硒的可利用状况。这里涉及的因素有土壤的pH值和通气性等,它们对植物吸收硒的数量影响很大,而酸性的或通气性不良的土壤所能提供给植物的可利用硒则很少。 通常硒在饲料中的含量     

Effect of organic and inorganic selenium sources and levels on sow colostrum and milk selenium content

A study was conducted to evaluate the short-term effects of feeding two dietary Se sources at various Se levels on the transfer of Se to the dam's milk and nursing pig. Six dietary treatments were arranged in a 2 x 2 factorial arrangement with two additional treatments in a randomized complete block designed experiment. Inorganic (sodium selenite) or organic (Se-enriched yeast) Se sources were added to the diet at .15 or .30 ppm Se. A non-Se-fortified corn-soybean meal basal diet served as a negative control, and a sixth group was fed .15 ppm Se from both inorganic and organic Se sources. A total of 43 sows were fed their treatment diets at 2.2 kg/d from 6 d prepartum to parturition and at full feed through a 14-d lactation period. Ten sows were initially bled at 6 d prepartum, and three sows and three pigs from their litters were bled at 7 and 14 d postpartum. Serum was analyzed for its Se concentration and glutathione peroxidase (GSH-Px) activity. Colostrum was collected within 12 h postpartum and milk at 7 and 14 d of lactation. When the basal diet was fed, sow serum GSH-Px activity declined from 6 d prepartum and remained low throughout lactation. When dietary Se levels increased, sow serum Se concentration and serum GSH-Px activity increased (P < .05) at both 7 and 14 d postpartum. The short-term feeding of either Se source at .15 or .30 ppm Se did not affect colostrum Se content when inorganic Se was fed, but it was increased when organic Se was provided. This resulted in a significant Se source x Se level interaction (P < .01). Milk Se at 7 and 14 d postpartum was 2.5 to 3 times higher when the organic Se source was provided and resulted in a significant Se source x Se level interaction (P < .05). When the combination of inorganic and organic Se was fed at .15 ppm Se, colostrum and milk Se contents were similar to those of sows fed .15 ppm Se from the organic Se source. Pig serum GSH-Px activity was not affected at 7 and 14 d of age by dietary Se level or Se source fed to the sow, but serum Se increased (P < .05) as dietary Se level increased, particularly when sows had been fed organic Se. The results demonstrated that organic Se increased milk Se content more than did inorganic Se and increased the nursing pig's serum Se. These results indicate that inorganic Se was more biologically available for sow serum GSH-Px activity, but organic Se was more effectively incorporated into milk.     

不同能量水平下三种有机铬对生长肥育猪生长性能及胴体品质的影响

将吡啶羧酸铬、烟酸铬、酵母铬分别以0.2mg/kg的浓度添加到两种不同能量水平的饲料中,探讨在两种能量水平下,3种有机铬对生长育肥猪的生长性能和肉品质的影响。结果显示,这6种饲料对生长肥育猪的日增重、料重比的差异显著(P<0.05);对45minpH值、滴水损失、背膘厚的影响差异不显著(P>0.05),对24hpH值、嫩度、眼肌面积、肉色的影响差异显著(P<0.05)。     

高温对不同体重生长猪采食量影响模式的研究

研究了不同环境温度T(23℃、26℃、29℃、32℃和35℃)对不同体重BW(20～40kg、40～60kg、60～80kg和80～100kg4个体重阶段)生长猪日均采食量(VFI)的影响,供试猪单个饲养于金属代谢笼中,每一体重阶段猪在不同温度下饲喂同一饲粮,自由采食和饮水。结果表明,高温对VFI有极显著的影响,影响的程度与猪的体重和高温的程度有关。20～40kg生长猪以26℃的VFI最高,但在23℃、26℃和29℃之间差异不显著(P>0.05),从32℃开始,VFI显著下降(P<0.05);40～60kg、60～80kg和80～100kg阶段从26℃开始,VFI就显著或极显著地低于23℃(P<0.05,P<0.01)。温度对全期(20～100kg)VFI的影响在23℃～32℃之间,呈线性下降,当温度由32℃升至35℃时,VFI的下降幅度加大,32℃比23℃、35℃比23℃和35℃比32℃温度每升高1℃时,VFI分别下降50g/d、65g/d和108g/d;VFI随温度的升高呈二次函数关系下降,其回归方程为:VFI(g/d)=1262.2420 89.5679T-2.6572T2(R2=0.98,RSD=29.15);VFI同时受温度和体重的双重影响,随体重和温度变化的回归方程为:VFI(g/d)=-1858.4446 86.6914BW 114.9760T-2.0148T2-0.3346BW2-1.1077T×BW(R2=0.96,RSD=91.72)。     

Dietary sodium and chloride levels for growing-finishing pigs

The performance and the physiological and metabolic consequences of three dietary levels of Na (.03, .09 and .18%) and of Cl (.08, .17 and .32%) arranged factorially were determined in growing-finishing pigs (36 to 89 kg). Average daily gain and feed efficiency of pigs fed .03% Na were lower than pigs fed .09 or .18% Na. Gain:feed ratio of pigs fed .32 or .17% Cl was greater than that of pigs fed .08% Cl during the finishing phase (58 to 89 kg) but not during the growing phase. Increasing dietary Cl levels increased average daily feed intake and gain:feed ratio of pigs fed .03% Na, but had no effect at the higher levels of Na. Plasma Na and Cl were lower (P less than .05) while plasma K (P less than .01), total protein, (P less than .04), albumin (P less than .07) and urea N (P less than .03) were higher in pigs fed .03% Na compared with those fed .09 or .18% Na. Increasing the dietary levels of Cl decreased urea N (P less than .05). Plasma lysine:arginine ratio increased as dietary Cl increased in pigs fed .18% Na diets, but not in pigs fed .03 or .09% Na. The urea cycle intermediate ornithine was highest in the plasma of pigs fed .18% Na. Dietary Na and Cl seem to interact to affect both plasma electrolytes and basic amino acid metabolism.     

A meta-analysis of the effects of high ambient temperature on growth performance of growing-finishing pigs

High ambient temperature (T) is one of the most important climatic factors influencing pig performance. Increased T occurs sporadically during summer heat waves in temperate climates and year round in tropical climates. Results of published experiments assessing the effects of high T on pig performance are surprisingly variable. Thus, a meta-analysis was performed to aggregate our knowledge and attempt to explain differences in the results across studies on the effect of increased T on ADFI and ADG in growing-finishing pigs. Data for ADFI and ADG were extracted from 86 and 80 trials, respectively, from articles published in scientific journals indexed in PubMed, Science Direct, and from proceedings of scientific meetings through November 2009. Data on ADFI and ADG were analyzed using a linear mixed model that included the linear and the quadratic effects of T and BW, and their interactions as continuous, fixed effects variables, and the trial as a random effect factor (i.e., block). In addition, the effects of housing type (2 levels: individual and group housing) and the year of publication (3 levels: 1970 to 1989, 1990 to 1999, and 2000 to 2009) on the intercept and the linear regression term for T (i.e., the slope) were also tested. Results showed that high T had a curvilinear effect on ADFI and ADG and that this effect was more pronounced in heavier pigs. Across T, ADFI was less when pigs were group-housed. The intercept and the regression coefficient (slope) for T were significantly affected by the year of publication. The effect of increased T was greater in more contemporary works, suggesting that modern genotypes could be more sensitive to heat stress than older genotypes of lesser growth potential. In conclusion, pig performance decreases at an accelerating rate as T is increased. The large between-study variability on the effects of high T on pig performance is partially explained by differences in pig BW and to a lesser extent by the year the study was published.     

Influence of organic versus inorganic dietary selenium supplementation on the concentration of selenium in colostrum,milk and blood of beef cows

Background

Selenium (Se) is important for the postnatal development of the calf. In the first weeks of life, milk is the only source of Se for the calf and insufficient level of Se in the milk may lead to Se deficiency. Maternal Se supplementation is used to prevent this.We investigated the effect of dietary Se-enriched yeast (SY) or sodium selenite (SS) supplements on selected blood parameters and on Se concentrations in the blood, colostrum, and milk of Se-deficient Charolais cows.

Methods

Cows in late pregnancy received a mineral premix with Se (SS or SY, 50 mg Se per kg premix) or without Se (control – C). Supplementation was initiated 6 weeks before expected calving. Blood and colostrum samples were taken from the cows that had just calved (Colostral period). Additional samples were taken around 2 weeks (milk) and 5 weeks (milk and blood) after calving corresponding to Se supplementation for 6 and 12 weeks, respectively (Lactation period) for Se, biochemical and haematological analyses.

Results

Colostral period. Se concentrations in whole blood and colostrum on day 1 post partum and in colostrum on day 3 post partum were 93.0, 72.9, and 47.5 μg/L in the SY group; 68.0, 56.0 and 18.8 μg/L in the SS group; and 35.1, 27.3 and 10.5 μg/L in the C group, respectively. Differences among all the groups were significant (P < 0.01) at each sampling, just as the colostrum Se content decreases were from day 1 to day 3 in each group. The relatively smallest decrease in colostrum Se concentration was found in the SY group (P < 0.01).Lactation period. The mean Se concentrations in milk in weeks 6 and 12 of supplementation were 20.4 and 19.6 μg/L in the SY group, 8.3 and 11.9 μg/L in the SS group, and 6.9 and 6.6 μg/L in the C group, respectively. The values only differed significantly in the SS group (P < 0.05). The Se concentrations in the blood were similar to those of cows examined on the day of calving. The levels of glutathione peroxidase (GSH-Px) activity were 364.70, 283.82 and 187.46 μkat/L in the SY, SS, and C groups, respectively. This was the only significantly variable biochemical and haematological parameter.

Conclusion

Se-enriched yeast was much more effective than sodium selenite in increasing the concentration of Se in the blood, colostrum and milk, as well as the GSH-Px activity.     

Effects of dietary levels of selenium-enriched yeast and sodium selenite as selenium sources fed to growing-finishing pigs on performance, tissue selenium, serum glutathione peroxidase activity, carcass characteristics, and loin quality.

This research evaluated the efficacy of inorganic and organic Se sources for growing-finishing pigs, as measured by performance and various tissue, serum, carcass, and loin quality traits. A total of 351 crossbred pigs were allotted at an average BW of 20.4 kg to six replicates of a 2x4 factorial experiment in a randomized complete block design. Pigs were fed diets containing Se-enriched yeast (organic) or sodium selenite (inorganic), each at .05, .10, .20, or .30 mg Se/kg diet. A non-Se-fortified basal diet was a ninth treatment group. Five pigs per pen were bled initially and at 30-d intervals with serum analyzed for Se and glutathione peroxidase (GSH-Px) activity. At 55 kg BW, one pig per pen from each of three replicates was killed, and tissues were collected for Se analysis. At 105 kg BW, the remaining pigs in the three replicates were killed, carcass measurements were collected, tissues were analyzed for Se, and loin quality was evaluated for pH, drip loss, and lightness. No performance or carcass measurement benefit resulted from either Se source or dietary Se levels. Pigs had a lower serum Se concentration and GSH-Px activity when the basal diet was fed, but both increased as dietary Se level increased (P<.01). Serum GSH-Px activities were increased by pig age and reached a plateau when the diet contained approximately .10 mg Se/kg (P<.01) at d 30, and 60 of the trial, and at .05 mg Se/kg diet at d 90 of the trial. The organic Se group fed .05 and .10 mg Se/kg had serum GSH-Px activities that tended to be lower than those of pigs fed the inorganic Se source, but GSH-Px activities in both groups were similar at higher Se levels. Tissue Se contents increased linearly as the dietary Se level increased, but the increase was markedly higher when organic Se was fed, resulting in an interaction (P<.01) response. Loin drip loss, pH, and lightness were unaffected (P>.15) by organic Se source or level, but there was a trend for a higher drip loss (P = .11) and a linear (P<.01) increase in loin paleness when the inorganic Se level increased. These results indicate that neither Se source nor Se level had an effect on pig performance or carcass measurements, but organic Se source increased tissue Se concentrations. Inorganic Se may, however, have a detrimental effect on loin quality, as reflected by higher drip loss and a paler color. Using serum GSH-Px activity as the measurement criterion, the supplemental dietary Se requirement did not seem to exceed .10 and .05 mg Se/kg diet for the growing and finishing phases, respectively, when added to a basal diet containing .06 mg Se/kg.     

Effect of dietary fluorine on growth, blood and bone characteristics of growing-finishing pigs

Three hundred eighty-four growing-finishing pigs were used in two experiments to determine the effect of dietary fluorine (F) on growth, blood and bone physical characteristics. Fourteen dietary treatments were formulated by supplementing F (as NaF) to a milo-soybean meal basal diet (7 ppm F) to provide levels of 7, 132, 257, 382, 507 and 632 ppm F for Exp. 1, and 7, 25, 43, 61, 79, 97, 115 and 133 ppm F for Exp. 2. Average daily gain (ADG) and average daily feed intake (ADFI) were not affected (P greater than .09) when F was fed at levels between 7 and approximately 132 ppm. Average daily gain and ADFI were reduced (P less than .0001) for pigs consuming diets with F concentrations greater than 132 ppm (Exp. 1). Feed conversion was not affected (P greater than .17) by any level of F fed. Serum F and alkaline phosphatase concentrations increased (P less than .01) with increasing dietary F levels. Serum and bone Ca and P concentrations were not affected (P greater than .13) by dietary F levels (Exp. 1). In Exp. 1 and 2, bone F increased (P less than .0001) and metatarsal stress and modulus of elasticity decreased (P less than .0001) as level of F increased in the diet. Bone thickness decreased quadratically (P less than .02) in Exp. 1 and linearly (P less than .0007) in Exp. 2 with increased dietary F levels. Scanning electron microscopy showed an increase in porosity of bones from pigs fed the higher levels of F. Growing-finishing pigs were able to tolerate approximately 132 ppm F for growth, but all of the F levels (greater than or equal to 7 ppm) fed in these two experiments affected bone integrity.     

Infleuce of dietary levels of vitamin E and selenium on tissue and blood parameters in pigs.

Eighteen barrows approximately three weeks of age were used in a 3 X 3 factorial arrangement to investigate the effect of level of supplemental vitamin E and selenium on tissue and blood parameters. Tissue selenium concentrations increased in a quadratic manner with increased selenium intake with kidney tissue containing considerably greater concentrations than liver, heart or muscle. Supplementation of the diet caused a three-fold increase in serum selenium within the first week with a slight tendency to further increases in subsequent weeks. Serum vitamin E of unsupplemented pigs declined by fifty percent during the experiment, whereas supplemental vitamin E resulted in increased serum vitamin E. There was a considerable viration in percent peroxide hemolysis. Correlation of -0.63 between percent peroxide hemolysis and vitamin E intake and -0.85 between percent peroxide hemolysis and serum vitamin E were observed.     

Effect of high temperature and low-protein diets on the performance of growing-finishing pigs

The effects of reducing CP level in combination with an increase in ambient temperature (29 vs 22 degrees C) on performance and carcass composition were studied in a factorial arrangement of treatments involving 66 Piétrain x (Landrace x Large White) barrows from 27 to 100 kg BW. Animals were fed at each temperature one of three experimental diets that provided 0.85 or 0.70 g of digestible lysine per megajoule of NE, in the growing (27 to 65 kg) and the finishing (65 to 100 kg) phases, respectively. Diet 1 was a corn, wheat, and soybean meal diet formulated without crystalline AA; CP levels were 20.3 and 17.6% for the growing and the finishing phases, respectively. In Diets 2 and 3, CP level was reduced by substituting part of the soybean meal with corn and wheat (Diet 2), or with corn, wheat, and 4% fat (Diet 3). Diets 2 and 3 were supplemented with AA and balanced according to the ideal protein concept. The CP levels of Diets 2 and 3 were, respectively, 15.8 and 16.3% in the growing phase, and 13.4 and 13.8% in the finishing phase. Pigs were housed individually and had free access to feed and water. The ADFI was measured daily, and animals were weighed weekly. Carcass composition was measured at slaughter (100 kg BW). Increasing ambient temperature from 22 to 29 degrees C resulted in a 15% reduction in ADFI and 13% lower ADG. Leaner carcasses (P < 0.01) were obtained at 29 degrees C (22.8 vs 24.8% carcass fat). At 22 degrees C, ADFI was lower (P < 0.05) for the low-CP diets, but daily NE intake, ADG, and carcass composition were not affected (P > 0.05). At 29 degrees C, ADFI was not different (P > 0.05) between diets and daily NE intake was higher (P < 0.05) with Diet 3 than with Diet 1, and the difference was more important during the finishing period than during the growing period. Using the model ADFI = a BWb, estimates of b were 0.65, 0.53, and 0.53 at 22 degrees C and 0.50, 0.44, and 0.50 at 29 degrees C, for Diets 1, 2, and 3, respectively. The higher NE intake for Diet 3 at 29 degrees C did not improve ADG (P > 0.05) but increased mainly fat deposition. These results indicate that a 4 percentage unit reduction of dietary CP level reduces N excretion (minus 37%) but does not affect growth and carcass composition as long as the ratio between essential AA and NE are kept optimal. In addition, diets with reduced CP limit the effect of high ambient temperature on ADFI. Finally, our results demonstrate the significance of using NE, rather than DE or ME, for formulating diets.     

利用产朊假丝酵母转化无机硒为有机硒的研究

对富硒酵母进行筛选并对发酵条件进行优化,得到富硒酵母的最适发酵条件:麦芽汁12°Be、培养基加Se量15mg/l、250ml三角瓶装量40ml、初始pH值为6.0、发酵时间40h、温度26℃、转速250r/min,经此培养所得的富硒酵母中的Se含量达到了1451.31μg/g。