Estradiol and progesterone concentrations resulting from the administration of an exogenous hormone regimen in diestrous embryo transfer recipients

Estradiol and progesterone concentrations were evaluated from diestrous embryo transfer recipient mares (5 to 14 days post-ovulation) which were treated with an exogenous hormone regimen. Upon detection of the donor mare's ovulation (0 hours), 10 mg PGF_2α was given to the recipient mare; at 12, 24 and 36 hours 20 mg estradiol cypionate; at 48 hours, 500 mg progesterone in oil and then 22 mg altrenogest at 60, 72 and 96 hours. Altrenogest (22 mg/day) was continued until end of the trial (detection of a fetal heart beat). Embryos were transferred non-surgically 6 or 7 days after the start of treatment.Plasma samples were evaluated over three periods; period 1-between recipient mare ovulation and prior to PGF_2α period 2-between PGF and embryo transfer and period 3-post-transfer. During periods 2 and 3, estradiol was higher (P<.05) for mares which were 10 to 14 days post-ovulation (late diestrous) as compared to mares which were 5 to 9 days post ovulation (mid-diestrous) when treatment began. Progesterone concentrations were higher (P<.05) for the mid-diestrous mares in the same periods. The pregnancy rate was higher for the late diestrous mares than the mid-diestrous mares (58% (7/12) vs 10% (1/10)). However, no difference (P>.05) was detected in estradiol or progesterone in the late diestrous mares which were pregnant or open. During period 2, estradiol was higher (P<.05) in the pregnant than open mares. Whereas, during period 3, progesterone was higher (P<.05) in the open mares.These data suggest that estradiol is important for the establishment of pregnancy in the mare. Furthermore, hormone treatment developed in this study appears to have some potential in synchronization of diestrus mares to be used as embryo recipients.     

Reversibility of furazolidone-induced cardiotoxicosis in ducklings

Furazolidone cardiotoxicosis was induced in 2 groups (FZ and FZ-CR groups) of newly hatched male Pekin ducklings (100/group) by feeding a ration containing 650 mg of furazolidone/kg of feed (ppm) for 28 days. A third group (control ration, CR group; n = 100) was fed the same ration without furazolidone. On day 28, the control ration was initiated for the FZ-CR group initially given the furazolidone-containing ration, to allow recovery from the effects of the drug, whereas ducklings of the FZ group continued to consume the furazolidone-containing ration. Biweekly, beginning with week 4, ducklings were euthanatized to assess severity of gross lesions and to obtain sections of myocardium for histologic and ultrastructural examination. Clinical evidence (increased weight gain, increased feed consumption, decreased mortality, reduced prevalence of palpable ascites) of regression of cardiotoxicosis of ducklings of the FZ-CR group was nearly complete by day 56 (28 days after cessation of furazolidone intake). Likewise, regression of gross lesions, as measured by overall prevalence of gross lesions, left ventricular volume, and ascites prevalence and severity, were also essentially complete by day 56. Myofibrillar lysis was not seen in sections from the heart (examined ultrastructurally) obtained from ducklings of the CR group that were euthanatized on day 28, 56, or 98. Myofibrillar lysis was detected in all ducklings (4/4) fed furazolidone (FZ and FZ-CR groups) and euthanatized on day 28. Myofibrillar lysis was not seen in the heart of ducklings of the FZ-CR group that were euthanatized on day 56 or 98. Myofibrillar lysis was detected in the heart from all ducklings of the FZ group that were euthanatized on day 56.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lysine and methionine transport by bovine jejunal and ileal brush border membrane vesicles

Lysine (LYS) and methionine (MET) transport were studied using brush border membrane vesicles from bovine jejunal and ileal tissues. Total transport of LYS and MET was divided into mediated and diffusion components. Mediated uptake was further divided into sodium (Na)-dependent and Na-independent systems. Total LYS and MET uptake by ileal brush border (BB) vesicles tended to be higher than that by jejunal BB vesicles at all concentrations evaluated but differences were significant (P less than .05) at 2.5 and 7.5 mM for LYS and 5, 12.5 and 15 mM for MET. The greater capacity of ileal BB vesicles appeared to be due to the Na-dependent component of LYS uptake and the diffusion component of MET uptake. Transporters had less affinity but higher capacity than for LYS transport in both ileal and jejunal tissue. Methionine transport was greater (P less than .05) than LYS transport in both ileal and jejunal BB vesicles when the initial amino acid concentration was 7.5 mM. But when the initial amino acid concentration was 1.25 mM, MET uptake was greater (P less than .13) than LYS uptake in jejunal, but not in ileal, BB vesicles. The relative contribution of mediated and diffusion uptake systems to total MET and LYS uptake was found to be dependent on substrate concentration. Both intestinal site and substrate concentration influenced the contributions of Na-dependent, Na-independent and diffusion systems to total methionine and lysine uptake.     

Intestinal acid flow, dry matter, starch and protein digestibility and amino acid absorption in beef cattle fed a high-concentrate diet with defluorinated rock phosphate, limestone or magnesium oxide

Five Angus heifers (285 kg) with duodenal and ileal cannulas were used to study the effects of feeding mineral acid neutralizers on digesta and fecal pH, intestinal acid flow, DM, starch and CP digestion and amino acid absorption in cattle fed a high-concentrate diet (7.5 kg/d). The experimental design was a 5 x 5 latin square. Treatments included control diet alone or control diet with the addition of 1.60% defluorinated rock phosphate-medium (DRP-M, 77% greater than 150 mu but less than 1,180 mu), 1.60% defluorinated rock phosphate-coarse (DRP-C, 85% greater than 850 mu but less than 1,700 mu), 1.28% limestone (92% greater than 150 mu but less than 850 mu) or .50% MgO, (81% greater than 250 mu but less than 1,180 mu), as an as-fed basis. Ileal pH was increased (P less than .05) from 7.49 to 7.85 by MgO. Fecal pH was increased (P less than .05) in this order: MgO (7.18) greater than DRP-M (6.86) = limestone (6.86) = DRP-C (6.75) greater than control (6.54). Liquid flow to the duodenum was increased (P less than .05) an average of 19.7% by the mineral treatments. Duodenal acid concentrations (mEq/liter) were greatest (P less than .05) for DRP-M (65.4) and DRP-C (64.0) vs limestone (55.5) and MgO (54.4). Acid flow to the intestine was increased (P less than .05) to 4.02, 4.53 and 4.82 Eq/d for animals fed limestone, DRP-M and DRP-C, respectively, from 3.51 Eq/d for control animals. Total tract DM, starch and CP digestibilities were similar (P greater than .10) among treatments. Limestone and DRP-M increased (P less than .10) the partial digestibility of most amino acids by about 6.8%. Mineral treatments did not increase total tract digestion of starch or CP. However, cattle fed DRP-M and limestone may have used protein more efficiently.     

Simultaneous isolation and characterization of brush border and basolateral membrane vesicles from bovine small intestine

Purified brush border and basolateral membranes were isolated from homogenized intestinal enterocytes of Holstein steers by divalent cation precipitation followed by differential and sucrose density gradient centrifugation. Alkaline phosphatase and Na/K adenosine triphosphatase served as marker enzymes for the brush border and basolateral membranes, respectively. The brush border and basolateral membrane fractions were enriched 5.1- and 10.1-fold, respectively, over the cellular homogenate. Electron micrographs, obtained with transmission electron microscopy, confirmed the vesicular nature of the membranes and revealed that basolateral membrane vesicles generally were smaller and more irregular in shape than brush border membrane vesicles. The vesicular nature of isolated membrane preparations was confirmed with osmotic activity experiments. Enrichment of brush border and basolateral membrane fractions compared to the initial homogenate and the vesicular configuration of both preparations indicate that the isolated brush border and basolateral membrane preparations were suitable models for evaluating nutrient transport properties of bovine small intestine. The number of transport experiments possible per animal using the membrane vesicle technique is many times more efficient than some other in vitro techniques (i.e., intestinal rings or everted sacs).     

Cystic testicular degeneration in furazolidone toxicosis of sexually immature ducks

Cystic testicular tubular dilatation was seen in ducklings fed a ration containing furazolidone at 250, 400, 550, or 700 ppm for 28 days. Gross evidence of cystic testicular dilatation was observed at necropsy in 16% (32/203) of the ducklings that survived to the end of the study. Gross testicular lesions consisted of various degrees of enlargement with increased translucency in moderately to severely enlarged testicles. Histological evidence of cystic testicular dilatation was present in 45% (41/91) of the testicles examined. Histologically, the tubules were in various states of dilatation with attenuation of the seminiferous epithelium proportional to the severity of dilatation. In the most severely affected testicles, tubules were greatly dilated, distorted, and fluid-filled, with extensively flattened epithelium visible on the inner margin of the tubule as a thin rim of cytoplasm with a protuberant nucleus. Interstitial tissues were compressed to thin septa between the dilated tubules.     

Stage 4 sleep: influence of time course variables

Age, length of prior wakefulness, length of time asleep, and a circadian influence all affect stage 4 sleep. The amount of stage 4 sleep decreases as subject's age increases and as time asleep increases. Longer periods of wakefulness before sleep result in greater amounts of stage 4 sleep in the first 3 hours of sleep. Sleep periods that begin at times other than the regular onset time tend to produce less stage 4 sleep; this decrease suggests a circadian effect.