Effect of dietary calcium on selenium retention in postweaning swine.

Two experiments were conducted to evaluate the effect of dietary Se and Ca on Se utilization in postweaning swine. Two levels of dietary Se (.3 or 5.0 ppm) supplemented as sodium selenite and four levels of total dietary Ca (.50, .80, 1.10 or 1.40%) in a 20% protein, corn-soybean meal diet were evaluated. Inorganic Ca was supplied from dicalcium phosphate and limestone. In Exp. I, 135 pigs weaned at 4 wk of age were allotted by sex, litter and weight and fed a basal diet for 7 d and then their treatment diets for a 28-d period. Plasma and tissue were collected at the end of the trial for Se concentration and glutathione peroxidase (GSH-Px) activity. Dietary Ca had no effect on gain or feed measurements but 5.0 ppm Se depressed daily gain slightly. When 5.0 ppm dietary Se was fed, there resulted higher liver, kidney, heart and longissimus muscle Se concentrations than when .3 ppm was provided, but dietary Ca had no effect on tissue Se values within each dietary Se level. Plasma GSH-Px increased when higher dietary Se was provided, whereas neither heart nor liver GSH-Px activity was affected by dietary Se or Ca level. In Exp. II, a 5-d balance trial was conducted with 32 barrows after adjustment to their treatment diet for a 28-d period. Selenium retention increased quadratically as dietary Ca increased, whereas Ca retention was not affected by dietary Se. These results suggest that low dietary Ca levels may reduce total Se retention but not Se metabolism within body tissue.

Effect of dietary phosphorus on selenium retention in postweaning swine.

Two experiments were conducted to evaluate the effect of dietary Se and P levels on Se retention in postweaning swine. A 20% protein corn-soybean meal diet at two dietary Se levels (.3 and 5.0 ppm) and four total P levels (.50, .70, .90, 1.10%) were fed. Supplemental Se was provided from sodium selenite with inorganic P from dicalcium phosphate. In Exp. I, 151 pigs weaned at 4 wk of age were allotted by sex, litter and weight and fed their treatment diets for 28 d after a 7-d adjustment to a basal diet. Dietary Se level had no effect on performance measurements. As dietary P level increased, there was an increase in daily gain, feed intake and a decrease in feed to gain ratio. Dietary P resulted in similar plasma, longissimus muscle and kidney tissue Se values within each dietary Se level, while liver Se declined as dietary P level increased. Dietary P level had no effect on plasma, heart or liver glutathione peroxidase (GSH-Px) activity. In Exp. II, 32 barrows, after being fed their diets for a 28-d period, were placed in individual metabolism crates where a balance trial was conducted. Dietary P level reduced absolute and percentage Se retention, particularly at dietary P levels of .90 and 1.10%. Phosphorus retention was not affected by dietary Se. Neither dietary P nor Se level had any effect on N retention. These results suggest an effect of dietary P level on Se retention and liver Se, particularly at dietary P levels above the pig's P requirement, while the effect is minimal at or below the pig's P requirement.

Effects of combining protein sources on lysine utilization by starter pigs.

The effect of combining protein sources on lysine utilization was evaluated using 450 crossbred starter pigs, average initial weight 6.8 kg and final weight 17.4 kg, in four replicates of 12 dietary treatments. Pigs were fed ad libitum a corn-soybean meal basal diet containing .65% total lysine, supplemented with one of four lysine sources: L-lysine X HCl, soybean meal, meat and bone meal and a combination of meat and bone meal and soybean meal with each providing equal lysine. The levels of supplemental lysine added to the basal diet by addition of the lysine sources were: 0, .15 and .30% L-lysine X HCl and .10, .20 and .30% for soybean meal, meat and bone meal and combination. All diets were calculated to meet or exceed the National Research Council recommendations for amino acids other than lysine. Gain and feed intake were measured over the treatment period. There was an effect (P less than .05) due to treatment on both average daily gain and gain/feed, but no effect calculated due to the independent variable of lysine intake for each of the lysine sources tested and the dependent variable of average daily gain or gain/feed. Response to the supplemental protein sources was linear. Gain and gain/feed were maximized when soybean meal fortified the basal diet. The data indicate that in weanling pigs to 17 kg body weight, lysine utilization from protein sources is not seriously affected by feeding the source in combination.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of swine weaning age on body fat and lipogenic activity in liver and adipose tissue.

Two experiments were conducted to evaluate the effects of weaning swine at 2 or 5 wk of age on postweaning performance and fat metabolism. In the first experiment, 52 pigs were weaned at 2 or 5 wk of age with body weights determined from birth to 8 wk. The early weaned group was fed a 20% protein corn-soybean meal-oat diet containing 25% dried whey from 2 to 5 wk while both groups were fed a 20% protein cereal grain-based diet from 5 to 8 wk of age. In a second experiment, a total of 90 pigs weaned at similar ages and fed the same diet sequences were killed at weekly intervals from 2 to 8 wk of age to evaluate body fat content and lipogenesis in liver and adipose tissue. Lipogenic capacity was measured by incorporation of acetate-1 14C into the total lipid fraction in liver slices and adipose tissue minces or by monitoring liver ATP citrate lyase activity. The results demonstrate that pigs weaned at 2 wk experience a slower postweaning growth rate with lower empty body weights than those either concurrently nursing the dam or weaned at 5 wk of age. Both groups had similar body weights from 6 to 8 wk of age. The body fat content of nursing pigs increased from 2 to 5 wk of age. Pigs weaned at 2 wk lost approximately 25% of their body fat the first week postweaning while later-weaned pigs did not lose body fat postweaning. Body fat composition of both groups was similar by 8 wk of age. Lipogenic activity was higher in liver than in adipose tissue from 2 to 5 wk of age and remained relatively constant throughout the trial. Adipose tissue lipogenic activity was lower in the nursing pig but increased dramatically at 5 wk in the early-weaned group and 7 wk of age in the late weaned group. These results suggest that weaning age can affect postweaning body fat composition and that adipose contributes a greater lipogenic capacity than liver tissue as the pig matures.

An evaluation of various biological characteristics in assessing low phosphorus intake in weanling swine.

A total of 204 weanling pigs were utilized in an experiment of 3 X 3 factorial design (in three replicates) to evaluate the effects of feeding low P diets for a 35 d period on various growth, serum and bone measurement characteristics. Total dietary P levels of .23, .35 and .55% were fed in a Ca:P ratio of 1:1, 1.5:1 or 3:1. The basal diet was formulated using cornstarch, dextrin and soy protein concentrate with monosodium phosphate and limestone used to supply appropriate dietary levels of Ca and P. Growth, serum minerals and serum alkaline phosphatase were evaluated at 21 and 35 d of the trial. At the end of the experiment six pigs/treatment group were killed and bones were collected for various measurement criteria. Daily gain, feed intake and feed conversion were not affected by Ca:P ratio, but there was an increased gain and feed intake response to dietary P level. Serum inorganic P decreased with increasing dietary Ca:P ratio and also increased linearly as dietary P level increased. Serum alkaline phosphatase activity was not influenced by dietary Ca:P ratio, but did decrease as dietary P level increased. Bone bending moment increased quadratically as Ca:P ratio increased, but also increased linearly with dietary P level. Percentage bone ash, bone ash and organic matrix weights and the accretion of both the mineral and matrix components were not affected by Ca:P ratio, but each was influenced as dietary P increased. These data suggest that percentage bone ash, bone component weights and accretion measurement characteristics were more sensitive indicators of dietary P levels than bone bending moment, serum alkaline phosphatase and serum P, which in turn were superior to serum Ca, Mg and growth performance.

Amino acid supplementation of low-protein diets for swine: effects of gestation treatment on reproductive performance of gilts and sows.

The effect of lysine and tryptophan addition to an all-corn diet fortified with vitamins and minerals fed to gestating gilts and sows was studied in a series of five trials. The experiments were designed to establish the effect of the addition of the two amino acids on: 1) N balance, 2) reproductive performance over two consecutive parities and 3) the immune response of the gestating gilt and transfer of immune proteins to the nursing pig. Nitrogen retention by gravid gilts fed an all-corn gestation diet increased (P less than .05) in response to lysine addition, but was not affected by subsequent addition of tryptophan. Daily N retention of gravid gilts fed the corn or corn and amino acid-supplemented diets was lower than that of gilts fed a 12% crude protein (CP) diet. Reproductive performance for two parities, as evaluated by gestation and lactation weight gain and, number and weight of pigs at birth and at 28 d was similar among treatments. Evaluation of the amino acid status of gestating gilts by measurement of the development of specific antibody response to sheep red blood cells and bovine serum albumin showed a trend for improved antibody development in gilts fed corn diets supplemented with both lysine and tryptophan and in the passive immunity of their offspring. Total whey protein and globulin content of 0-h colostrum was not affected by dietary treatment. The lack of a depression in reproductive performance of gilts fed an all-corn diet could be because of compensatory N retention. During the 4 to 5 d before parturition, all gilts were fed the 12% protein control diet. Gilts that were fed a corn diet from d 1 to 108 of gestation retained 40% more (P less than .01) N from d 109 to 114 of gestation than gilts that had been fed the 12% protein diet throughout gestation.