Long-haul transport and lack of preconditioning increases fecal shedding of Escherichia coli and Escherichia coli O157:H7 by calves.

The effects of weaning and transport on fecal shedding of Escherichia coli and on E. coli O157:H7 were investigated using 80 Angus and 94 Charolais range steer calves blocked by breed and assigned to four treatments. The calves were or were not preconditioned before transport on commercial cattle liner to the feedlot via long (15 h) or short (3 h) hauling duration, yielding preconditioned long haul (P-L; n = 44), preconditioned short haul (P-S; n = 44), nonpreconditioned long haul (NP-L; n = 43), and nonpreconditioned short haul (NP-S; n = 43). Preconditioned calves were vaccinated and weaned 29 and 13 days, respectively, before transport. Nonpreconditioned calves were weaned 1 day before long or short hauling, penned for 24 h and hauled again for 2 h, and vaccinated on arrival at the feedlot. Fecal samples were collected from calves while on pasture, at weaning, at loading for transport, on arrival at the feedlot, twice in the first week, and on days 7, 14, 21, and 28 for enumeration of total E. coli (biotype 1) and detection of E. coli O157:H7. No calves were positive for E. coli O157:H7 before transport. Following transport, more (P < 0.005) NP-L calves (6 of 43) tested positive for E. coli O157:H7 than did P-L (1 of 44), NP-S (1 of 43), or P-S (0 of 44) calves, and on days 0, 1, 7, and 21, their levels of shedding of E. coli were higher (P < 0.005). The calves' susceptibility to infection from the environment (possibly the holding facilities or feedlot pens) was likely elevated by the stresses of weaning, transport, and relocation. Lack of preconditioning and long periods of transport (NP-L) increased fecal shedding of E. coli and E. coli O157:H7. Preconditioning may serve to reduce E. coli O157:H7 shedding by range calves on arrival at the feedlot.

Blood and serum components and organ weights in steers, bulls and zeranol-implanted bulls.

To investigate certain physiological aspects of the mode of action of zeranol or Ralgro on growth, behavior and carcass quality of young bulls, concentrations of 19 blood components and weights of eight organs were determined. Experimental animals consisted of 36 untreated steers, 36 untreated bulls, 36 bulls implanted with zeranol at 3 mo of age and subsequently at 5, 8 and 10 mo and 36 bulls implanted with zeranol at 6 mo of age and subsequently at 9 and 11 mo. In addition, half of the animals in each group were subjected to moderate pre-slaughter stress (mixing and trucking 160 km); the other half was subjected to minimum pre-slaughter stress (no mixing and 4 km transport). Concentrations of cortisol, urea nitrogen and albumin in serum were higher (P less than .01) and those of glutamic oxaloacetic transaminase (GOT), lactate dehydrogenase (LDH), alkaline phosphatase (AP) and creatinine were lower (P less than .05) in steers than in intact males. Concentrations of GOT, LDH, and creatinine were higher (P less than .05) in implanted than those in control males. Pre-slaughter stress had a significant effect on several traits measured in blood or serum. Thyroid glands were smaller (P less than .01) in steers than in control and implanted males. Testes were smaller (P less than .01) in the zeranol-implanted than in untreated males. Results indicate that zeranol had only a minor effect on the 19 blood components studied, but it did reduce testicle size. Castration had a major impact on several of the blood components. Pre-slaughter management had a significant effect on several blood components.

Fetal-maternal transfer of [H3]-6 beta-hydroxycortisol in the pregnant ewe.

Distribution and fetomaternal transfer of 6 beta-hydroxycortisol (6 beta-OHF) was studied using serial sampling following injection of tritium labelled 6 beta-OHF into various fluid compartments in the chronically cannulated unaesthesized pregnant ewe. There was a rapid transfer of 6 beta-OHF from the fetal circulation into amniotic fluid and maternal blood. In contrast, the maternal----fetal transfer of this steroid metabolite was considerably less. The sequence of appearance of 6 beta-OHF in fetal blood and amniotic fluid following injection into maternal blood suggests that this steroid is first transferred across the placenta to fetal blood before gaining entry into the amniotic fluid space. The half-lives of 6 beta-OHF after initial equilibration in maternal plasma, fetal plasma and amniotic fluid were 2.0 h, 5.1 h and 8.9 h respectively. The amniotic sac appears to contain a relatively static pool of 6 beta-OHF and may act as a "trap" for 6 beta-OHF in the ovine conceptus.

Induction of oestrus and fertility in the anoestrous ewe with hormones and controlled lighting and temperature.

A programme consisting of 14 daily injections of progesterone (10 mg) followed by single injection of PMSG (500 i.u.) and oestradiol- 17 beta (30 micrograms), along with controlled temperature (18-20 degrees C) and lighting (10 h light/24 h), was applied to 60 anoestrous ewes between late May and early August to induce reproductive activity. Breeding started within 24 h of the oestradiol injection and 80.0% of the ewes conceived at the induced oestrus. Dorset ewes had higher conception (95.2 versus 71.8%) and prolificacy (1.74 versus 1.52 fetuses/ewe) rates than did crossbred Suffolk ewes. Plasma progesterone concentrations during progesterone administration were significantly higher than those found during anoestrus and were generally lower in ewes which did not conceive than in those which did. The plasma progesterone data indicated that ovulation had occurred in most of the ewes which were not pregnant at 90-100 days and that many may have been pregnant initially but then lost the conceptus.

Fetal-maternal distribution of ovine alpha-fetoprotein.

The concentration of ovine alpha-fetoprotein (AFP) was determined in sheep fetal, maternal, and neonatal sera and amniotic fluid by radioimmunoassay. The fetal serum AFP concentration was highest during the first third of pregnancy and continued to decline with fetal and neonatal development. Total fetal synthesis of AFP was highest during the late middle and early latter third of pregnancy. Amniotic fluid AFP concentration was highest during the early middle third of pregnancy. Maternal serum AFP was not elevated above nonpregnant control levels during the first two-thirds of pregnancy, but instead showed a tendency to be elevated only during the last third of pregnancy. The fetal physiological distributions of ovine and human AFP in fetal serum and amniotic fluid appear to be similar, whereas in maternal serum the pattern of AFP levels differs in the two species as a function of gestational age.

The effects of NA872 on pulmonary maturation in the fetal lamb and rabbit.

The effect of fetal administration of NA872, metabolite VIII of Bisolvon, on the lecithin/sphingomyelin (L/S) ratio of ovine tracheal fluid and of its administration to the pregnant doe on the fetal rabbit pulmonary pressure-volume relationship was determined. Intravenous administration of NA872 in the long-term cannulated lamb fetus in a dose of 4 mg. per day from either 120 to 125 or 125 to 130 days of gestation produced a significant increase in the L/S ratio. Administration of 4 mg. per kilogram per day to the pregnant doe on days 21 to 24 of gestation resulted in significant enhancement of lung maturation in the 25 day fetal rabbit lung as judged from the pressure-volume relationship; a smaller dose, or the same total dose given over shorter time periods, had no significant effect in the 25 day rabbit fetus. Similarly, 8 mg. per kilogram given to the doe on days 26 and 27 produced no over-all significant effect on the 28 day rabbit fetus, although a seasonal effect was found at this age.

Glucose metabolism and lipid mobilization by adipocytes from mice selected for growth.

1. Experiments were conducted to compare the abilities of epididymal adipocytes from mice selected for growth (line G) and from unselected mice (line C) to: (a) incorporate glucose, (b) respond to insulin, and (c) mobilize lipids, and to relate these abilities to the food intake of the donors.2. During the 3-week pre-experimental period, line G mice gained body weight 78% faster and ate 35% more food than line C mice; both lines had similar intakes per unit of metabolic body size.3. Line G epididymal fat pads weighed 227% more than those of line C and contained adipocytes which were 38% larger; it was estimated that they contained approximately 65% more cells.4. The basal rate of glucose incorporated into lipids (per unit protein) was highest in line C adipocytes, whereas the basal rates of glucose oxidation to CO(2) and the total glucose incorporation (uptake) were similar for adipocytes from both lines.5. Insulin (1000 muu./ml.) caused adipocytes from both lines of mice to increase significantly the incorporation of glucose into CO(2) and lipids; the largest elevation occurred when the incubation medium contained 0.1 mg glucose/ml. At this concentration of glucose, the minimum effective dose (MED) of insulin to produce a significant increase in glucose oxidation was similar for both lines. However, the MED of insulin necessary to significantly increase glucose incorporation into lipids and into the sum of CO(2) and lipids was highest in the larger, line G adipocytes. Furthermore, the magnitude of the insulin-induced increase in glucose incorporation was much less for line G than for the line C adipocytes.6. Epinephrine significantly elevated the rates of NEFA and glycerol release and NEFA re-esterification. The highest rates of NEFA and glycerol release occurred in line C adipocytes, whereas the highest rate of NEFA re-esterification occurred in the line G adipocytes.7. Glucose had no effect on NEFA release but significantly elevated the rates of glycerol release (in most instances) and NEFA re-esterification.8. The larger number of adipocytes in line-G adipose tissue allows for more total incorporation of glucose and a greater overall release of glycerol by this tissue. Consequently, a greater reduction of glucose concentration and a larger elevation of glycerol concentration in the blood can occur; either of these could be the feed-back signal which resulted in the larger long-term food intake by the line G mice.

Correlation of food intake in lambs with adipocyte glucose metabolism and NEFA release.

1. Experiments were conducted with lambs to determine the correlation between food intake, rate of glucose incorporation into CO(2) and lipids, and rate of lipid mobilization by their isolated omental adipocytes.2. During the interval between weaning and slaughter average daily dry matter (ADDM) intakes of the individual lambs were significantly correlated with average daily gains; however, the ratio of ADDM intake to body wt.((3/4)) was similar in all individuals.3. The average size of adipocytes for each lamb, as determined by lipid: protein ratios, was not significantly correlated with food intake.4. Oxidation of glucose to CO(2) and the total measured glucose incorporation by the adipocytes were significantly and negatively correlated with lamb ADDM intakes at low levels of glucose (0.1 mg/ml.), whereas rates of lipogenesis from glucose were similar for all intake levels.5. Insulin-induced increases in glucose utilization were positively and significantly correlated with ADDM intakes to the extent that insulin had over twice the effect on the adipocytes from high-intake lambs as it had on those from low-intake lambs. The minimum effective dose of insulin necessary to significantly increase glucose utilization by the adipocytes was also positively and significantly correlated with the ADDM intakes of the lambs.6. Basal NEFA release rates were higher for adipocytes from low-intake lambs. Epinephrine significantly increased NEFA release rates, independent of lamb intakes.7. A larger number of adipocytes in the high-intake lambs means that they would have a greater total potential to lower blood glucose, particularly when they are under the effects of normal circulating levels of insulin. The amount of glucose removed from the glucose pool could be the feed-back signal which results in a high long-term food intake.