Biological characteristics for assessing low phosphorus intake in growing swine

A total of 195 swine from 18 to 35 kg were used to evaluate various biological responses of growing swine fed low P diets at different Ca:P ratios. Three replicates of a randomized complete-block design in a 3 X 3 factorial arrangement of treatments were used. Total dietary P levels of .12, .31 and .50% were fed in 1:1, 1.5:1 or 3:1 Ca:P ratios. Diets were formulated using corn starch, dextrin and soy protein concentrate, with monosodium phosphate and limestone used to supply appropriate dietary treatment levels of Ca and P. Gain and feed performance were generally influenced by both Ca:P ratio and dietary P level. Serum inorganic P decreased linearly as Ca:P ratio widened and increased linearly as dietary P increased. Serum Ca concentrations responded inversely to serum inorganic P in response to both Ca:P ratio and dietary P level. Serum alkaline phosphatase was not affected by Ca:P ratio, but declined quadratically with increasing dietary P level. Bone bending moment was influenced by both dietary P level and Ca:P ratio. Bone component weights (ash, organic matrix), percentage bone ash and net accretion of bone ash and organic component weights were not influenced by Ca:P ratio but increased linearly as dietary P level increased. These results suggest that bone component weights, net ash accretion and percentage bone ash were more sensitive criteria than bone bending moment or serum alkaline phosphatase, which in turn were more sensitive than serum inorganic P, Ca, Mg and growth performance characteristics in response to dietary P level.     

Characterization of a repetitive DNA probe for Babesia bigemina

A plasmid (p16) containing a Babesia bigemina DNA insert was selected and labeled with 32P. This probe was evaluated for specificity and sensitivity by dot blot hybridization. The probe was specific and hybridized with only Babesia bigemina DNA, and not DNA from Babesia bovis, bovine leukocyte, Trypanosoma brucei or Anaplasma marginale. The DNA probe detected as little as 10 pg of Babesia bigemina DNA. The probe hybridized with Babesia bigemina isolates from Mexico, the Caribbean region and Kenya. Genomic Babesia bigemina DNA of a Kenyan isolate was digested with restriction endonucleases, and the fragments were separated by gel electrophoresis and Southern blotted. The filter was hybridized with labeled p16 and each endonuclease digestion produced at least 16 resolvable DNA fragments. The inserted Babesia bigemina DNA was approximately 6.3 kb in size. A partial restriction map was constructed. A simple whole blood dot blot procedure was utilized to evaluate the sensitivity of the DNA probe. This probe would detect as few as 150 Babesia bigemina infected erythrocytes contained in a 1-microliter sample. The DNA probe has the potential to be a very sensitive and specific diagnostic tool.     

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)     

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.     

Comparison of three enzyme-linked immunosorbant assays with the indirect immunofluorescent antibody test for the diagnosis of canine infection with Ehrlichia canis

The aim of this study was to compare three different enzyme-linked immunosorbant assays (recombinant major antigenic protein 2 (rMAP2)-ELISA, the Immunocomb (Biogal, Israel) and the Snap 3Dx assay (IDEXX Laboratories Inc., USA)) with the indirect immunofluorescent antibody test in detecting anti-Ehrlichia canis immunoglobulin-G (IgG) antibodies. Samples tested were collected from dogs suspected to be naturally infected with E. canis and from experimentally infected dogs.When qualitative results (positive/negative) were compared, there was an overall agreement of 81% (54/67) between the indirect immunofluorescence antibody (IFA) test and the rMAP2-ELISA. An overall agreement of 94% (63/67) was found between the IFA test and the Immunocomb, and an overall agreement of 91% (61/67) was found between the IFA test and the Snap 3Dx assay. In 50 of 67 (74.6%) samples tested, complete agreement in the qualitative results was found in all four tests. Sixteen of 17 samples with disagreement in the qualitative results were found to have IFA titers of 1:320 or less. The sensitivities and specificities of the tests were found to be 0.71 and 0.85 for the rMAP2-ELISA, 0.86 and 0.98 for the Immunocomb, and 0.71 and 1.00 for the Snap 3Dx assay.The tests performed in this study were found to be highly specific in detecting E. canis antibodies. Their sensitivity was found to be low with sera having IFA titers of < or =1:320, while high with sera having titers greater than 1:320. Repeating the serological tests 1-2 weeks after the first antibody assay may overcome the sensitivity problem with titers of < or =1:320.     

Effect of feed intake during late development on pubertal onset and resulting body composition in crossbred gilts.

A total of 105 nonboar-exposed, F2 ([Landrace x Yorkshire] x Duroc) gilts were used in two replicates of a randomized complete block experiment to evaluate the effect of dietary feed intake on pubertal onset and subsequent body composition. Feed intakes were established at 50% of ad libitum (AL-50), 75% of ad libitum (AL-75), or at ad libitum (AL-100) levels from 4.5 to 9 mo of age. A corn-soybean meal diet fed to all gilts was formulated to meet or exceed nutrient requirements except for energy. Puberty was measured by two methods: 1) monitored once daily by back pressure applied by the herdsman or 2) from elevated plasma progesterone concentrations. Body composition was evaluated by the deuterium oxide method after plasma progesterone concentrations were elevated. Daily feed intake for the experimental period averaged 1.6, 2.3, and 3.2 kg, and the BW of gilts at 8 mo of age were 111, 131, and 154 kg for the AL-50, AL-75, and AL-100 groups, respectively. Body weight, backfat thickness, and body fat content increased linearly (P < .01) as feed intake increased, but age at puberty was not severely influenced. A minimum body fat content or percentage did not seem to initiate pubertal onset. There was a trend for a lower percentage of the AL-50 gilts to ovulate (P = .08) than those fed the AL-75 and AL-100 intakes. An inverse relationship resulted between the percentage of gilts that ovulated to the percentage that showed behavioral estrus.(ABSTRACT TRUNCATED AT 250 WORDS)     

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)