Failure of conservative treatment for lumbar spinal stenosis in elderly patients.

Spinal stenosis syndrome affects mainly patients at their 5th-6th decades of life. There is a strong debate in the literature whether patients with spinal stenosis should be operated or treated conservatively. Our aim was to evaluate patients with lumbar spinal stenosis who were treated conservatively. All patients over 65 years of age who were handled conservatively in the private clinic of the senior author due to spinal stenosis syndrome were evaluated. There were 21 males and 15 females aged between 65 and 88 years. Intermittent claudication was the dominant clinical presentation. The radiological examination showed a frequent narrowing at the level L4-L5. All patients had a severe stenosis of less than 10mm diameter of the spinal canal. All patients underwent a conservative therapy which included physical therapy with ultrasound waves, short waves, and flexion exercises. All patients were offered to undergo an epidural or nerve root injection. Twenty-four patients agreed also to have one of these procedures to relieve their symptoms. All patients were followed between 6 and 10 months after the initial diagnosis. We used the Oswestry index category for evaluation. In all parameters the conservative treatment failed to improve the symptoms in the vast majority of patients. None of the patients was very satisfied with the results of conservative treatment while 33 patients (92%) were not so satisfied or unsatisfied with the results. We conclude that conservative treatment for lumbar spinal stenosis is not a success for elderly patients. These patients should be convinced to undergo operative treatment.

Endocrine alterations associated with extended time interval between estrus and ovulation in high-yield dairy cows.

Short fertile half-lives of the male and female gametes in the female tract necessitate accurate timing of artificial insemination. We examined the possible association between extension of the estrus to ovulation (E-O) interval and alterations in concentrations of estradiol, progesterone, and the preovulatory LH surge before estrus and ovulation. High-yielding Holstein cows (n = 74 from a total of 106) were synchronized and were examined around the time of the subsequent estrus. They were observed continuously for estrual behavior. Blood samples were collected before and after estrus, and ultrasound checks for ovulation were made every 4 h. About three-quarters of the cows exhibited short (but normal) E-O intervals of 22 to 25 h (25%) or normal intervals of 25 to 30 h (47%); 17% of them displayed a long (but normal) E-O interval of 31 to 35 h, and about 10% exhibited a very long E-O interval of 35 to 50 h. Extended E-O interval comprised estrus-to-LH surge and LH surge-to-ovulation intervals that were both longer than normal. Pronounced changes in hormonal concentrations were noted before ovulation in the very long E-O interval group of cows: progesterone and estradiol concentrations were reduced, and the preovulatory LH peak surge was markedly less than in the other 3 groups. Postovulation progesterone concentrations during the midluteal phase were lesser in the very long and the long E-O interval groups compared with those in the short and normal interval groups. Season, parity, milk yield, and body condition did not affect the estrus to LH surge, LH surge to ovulation, and E-O intervals. The results indicate an association between preovulatory-reduced estradiol concentrations and a small preovulatory LH surge, on the one hand, and an extended E-O interval, on the other hand. Delayed ovulation could cause nonoptimal timing of AI, a less than normal preovulatory LH surge that may be associated with suboptimal maturation of the oocyte before ovulation, or reduced progesterone concentrations before and after ovulation. All may be factors associated with poor fertility in cows with a very long E-O interval.

Pulsed radiofrequency in the treatment of patients with chronic neuropathic spinal pain.

In recent years there has been debate among spinal surgeons, neurosurgeons and pain physicians regarding the efficacy of radiofrequency (RF) ablation when treating patients with a neuropathic pain source. It is usually considered as a treatment option after conservative treatment has failed. Twenty-eight patients with a minimal follow-up of 1 year were examined in our institution after they had undergone pulsed radiofrequency (PRF) procedures due to neuropathic spinal pain. Nineteen patients (68 %) reported long-term pain relief (more than 1 year) which was defined as a reduction of the visual analogue score by at least 30 %. No complications were found in this study except for mild discomfort in the treated area which spontaneously resolved up to 3 weeks after the procedure. We concluded that PRF is a safe and an effective procedure for patients who suffer from chronic neuropathic pain from spinal origin. It should be tried after conservative treatment has failed.

Decompression surgery for lumbar spinal stenosis in the elderly: preoperative expectations and postoperative satisfaction.

STUDY DESIGN: Retrospective cohort examination. OBJECTIVES: Data on expectations and satisfaction rates in elderly patients operated for lumbar spinal stenosis (LSS) are limited. The present study aimed to investigate these issues as well as the factors that might affect them. SETTING: A university affiliated hospital. PATIENTS AND METHODS: A follow-up study of 367 consecutive patients aged 65 years and older (mean age 71.4 years), who underwent surgery for degenerative LSS between 1990 and 2000. Data collection included patients' preoperative expectation, demographic data, body mass index, operative risk, duration of symptoms, clinical presentation and patients' satisfaction on follow-up, pain level, activities of daily living level and walking ability. Data were recorded before operation and on follow-up. Preoperative and follow-up data were analyzed by univariate and multivariable models. RESULTS: The response rate on follow-up was 81% (298 patients). A logistic regression analysis showed that advanced age, male gender and high education level were independently associated with positive expectations, while a great number of covariates were associated with patients' satisfaction. High patients' expectations were positively interrelated with satisfaction (r=0.332, P<0.001). CONCLUSIONS: In the elderly, preoperative expectations reasonably predict their postoperative satisfaction rate. It is suggested that a greater effort should be made to narrow the gaps between expectations and satisfaction, perhaps by providing more accurate preoperative information data regarding the outcomes of planned surgery.

The effect of insoles on the incidence and severity of low back pain among workers whose job involves long-distance walking.

The prevalence and incidence of low back pain in general society is high. Workers whose job involves walking long distances have an even higher tendency to suffer from low back pain. A positive effect of insoles in reducing low back pain was found in professional sports players. This was not examined on people whose job involves walking long distances. In this double blind prospective study we examined the effectiveness of insoles constructed in a computerized method to placebo insoles in 58 employees whose work entailed extensive walking and who suffered from low back pain. The evaluation was performed by the MILLION questionnaire, which is considered as a valid questionnaire for evaluation of low back pain. We calculated the differences of the pain intensity before and after the intervention, in the employees using the insoles manufactured by computer in comparison to the users of the placebo insoles. In each group, the analysis was performed in comparison to the baseline. A total of 81% of the employees preferred the real insoles as effective and comfortable in comparison to 19% of the users of the placebo insoles (P<0.05). The results of this study indicate a substantial improvement in the low back pain after the use of the true insoles. The average pain intensity according to the MILLION questionnaire before the use of the insoles was 5.46. However, after the use of the real insoles and the placebo insoles, the average pain intensity decreased to 3.96 and 5.11, respectively. The difference of the average pain intensity at the start of the study and after the use of the real insoles was significant: -1.49 (P=0.0001), whereas this difference after the use of the placebo insoles was not significant: -0.31 (P=0.1189). The reported severity of pain also decreased significantly: a level 5 pain and above was reported by 77% of the subjects at the start of the study. After the use of the real insoles only 37.9% of the subjects reported a similar degree of pain severity, and 50% of the subjects did so after the use of the placebo insoles (P< 0.05). We did not find a link between low back pain and other variables such as gender, age, number of offspring, work seniority, smoking, previous use of insoles and previous medication. This study demonstrates that the low back pain decreased significantly after the use of real insoles compared to placebo ones.

Percutaneous posterior lumbar interbody fusion using the B-twin expandable spinal spacer.

Sixty-two suitable subjects (mean age: 49.3 years) underwent percutaneous posterior lumbar interbody fusion (PPLIF) using the B-Twin expandable spinal spacer (B-Twin ESS) and were followed thereafter for 2 years or longer. The clinical outcome was expressed by the change in pain intensity as scored on a visual analogue scale and the change in degree of disability as scored by the Oswestry Disability Index. The results were compared with those of a previous trial of PLIF using the B-Twin ESS in which the latter was introduced via the open surgical approach (OPLIF). Mean duration of operation was 103 minutes. Blood loss was negligible. No operative difficulties or complications were encountered. No participant was lost to follow-up. Disc space height had increased by a mean of 10 %. At that time there were no radiographic signs of non-union in any patient. The mean pain intensity and disability scores decreased by 66 % and 61 %, respectively, as compared to those on admission. The clinical outcome of the percutaneous method was comparable to that of the open procedure using the B-Twin ESS; however, the results can be interpreted as favoring the former in the context of minimal invasiveness. Should this outcome be validated in further trials, the technique may be adopted in selective cases.

Does obesity affect the results of lumbar decompressive spinal surgery in the elderly?

The prevalence of obesity among the population is increasing, including in many elderly people. The purpose of this study was to evaluate whether lumbar spinal surgery in elderly patients with different body mass indices influences pain, satisfaction rate, and activities of daily living. Two hundred ninety-eight elderly patients (older than 65 years), 153 women and 145 men, who had decompressive laminectomy, discectomy, or combinations of these procedures during 1990 to 2000 were followed up. Indications for surgery included limitation in doing activities of daily living, severe pain, or both. The patients were classified into one of four categories in terms of their body mass index. The operative parameters, pain reduction, satisfaction rate, and activities of daily living using the Barthel index were assessed. The more obese patients were younger, tended to be female, and were more symptomatic. All four groups of patients had reduction in pain, improvement in activities of daily living, and were satisfied with the operation. Our data suggest that it is reasonable to operate on patients who are elderly and obese and who have lumbar symptoms, with the appropriate indications.

Operative treatment for hip fractures in patients 100 years of age and older: is it justified?

OBJECTIVES: To evaluate a unique group of elderly patients over 100 years of age who had hip fractures. DESIGN: Retrospective database analysis. SETTINGS: Academic teaching hospital. PATIENTS: All patients who had hip fractures between January 1990 and December 2001 and were over 100 years old were included. INTERVENTION: In this study, we evaluated the age, gender, type of fracture, type of treatment, background disease, rehabilitation, and time until death of all patients over 100 years, whether treated operatively or nonoperatively. RESULTS: Twenty-three patients (17 females and 6 males) were identified with ages ranging from 100 to 107 (mean: 101.8). The group had 4 subcapital and 19 pertrochanteric fractures and between 1 and 4 major background diseases. Four patients were treated nonoperatively (1 due to major pneumonia and 3 refused the operative procedure). Three of those 4 patients died in the same month of admission, and 1 patient died during the second month. Among the 19 patients who underwent operation, 17 patients have died, living between 0 and 78 months (mean: 13.8) postoperatively. Two are still alive (21 and 45 months) after the operation. Eight patients died prior to 6 months, and 11 lived more than a year after the operation. A comparison between these 2 groups showed greater major background disease in the patients who died prior to 6 months (P < 0.05). CONCLUSIONS: Most hip fractures in patients over 100 years of age are pertrochanteric. Patients with 2 or more major background diseases have an increased risk for dying in the first 6 months after the operation. Most patients having operations in this age group had a postoperative reduction in mobility status and in performing basic activities of daily living.

[Relief of chronic cervical pain after selective blockade of zygapophyseal joint].

Osteoarthrosis of the zygapophyseal joint (Z-joint) is a potential cause of chronic cervical pain. The diagnosis of thirty patients, with pain of more than 12 months duration and with no history of trauma, was confirmed with intra-articular fluoroscopy-guided infiltration of anesthetic. The patients were subsequently treated with intra-articular corticosteroids (Depo-Medrol 40 mg). Visual Analogue Scale was used for evaluation purposes. The mean time for relapse of 50 percent of the pre-injection level of pain was 12.47 +/- 1.89 weeks, significantly longer than 3 days as reported in patients similarly treated following whiplash neck injury. At this point selective blockade of Z-joints may be offered as an adjunct for diagnostic and therapeutic purposes for patients with chronic neck pain due to facet osteoarthrosis in the ambulatory setup.

Rehabilitation after knee immobilization in octogenarians with patellar fractures.

Between January 1990 and December 1999, 14 octogenarians (8 women and 6 men) underwent surgery for comminuted patellar fracture. Average patient age was 83 years (range: 80-88 years). Follow-up ranged from 1-8 years (mean: 3.5 years). Ten of 14 patients were totally independent, whereas 4 patients used a cane for mobilization. Twelve patients had background diseases. Patients underwent operative treatment with tension band wires followed by cast immobilization (knee in approximately 10 degrees of flexion) for 6 weeks. Immediate full weight bearing was initiated in all patients, and intense rehabilitation was performed after cast removal to increase range of motion. Complete union was noted for all fractures. All patients but 1 had an active extension lag of 10 degrees-20 degrees before physiotherapy and maximum flexion was 70 degrees. After physiotherapy, 4 patients regained full active extension and all patients achieved >100 degrees of flexion. Twelve of 14 patients returned to their pre-injury functional level. A slight deterioration was noted in 2 patients. Although knee immobilization may cause severe limitation in range of motion, its use in elderly patients followed by intense rehabilitation is advocated and showed good results.

Reinnervation of the neurogenic bladder in the late period of the spinal cord trauma.

STUDY DESIGN: Intercostal nerve to spinal nerve root anastomosis in chronic spine-injured patients. OBJECTIVES: To analyze the effectiveness of neurogenic bladder reinnervation in spinal cord-injured patients through artificial creation of sprouting (intercostal nerve to spinal nerve root anastomosis). SETTING: Center of Neurosurgery, Moscow, Russia. Operations were performed by Professor A Livshits. (At present, Professor A Livshits is working at the Spinal Care Unit, Meir General Hospital, Kfar Saba, Israel.) METHODS: A total of 11 patients with spinal cord injury of the L1 level were operated on in the late (chronic) stage. The neurological status and urodynamics were investigated before and 12 months after operation. A laminectomy from T11 to L3 was performed. Next, a neurolysis of the 11th and 12th intercostal nerves was carried out, at a distance of 20-21 cm, and transferred to the vertebral canal. The S2-S3 roots were then cut in their proximal portion and anastomosed end-to-end to the intercostal nerves. The results of urodynamic studies were calculated by the Wilcoxon signed rank test for comparison before and 12 months after operation. RESULTS OF URODYNAMIC STUDIES: Bladder capacity (ml) before operation - 489+/-79, after operation - 350+/-39, urine volume (ml) before - 18.2+/-17, after - 306.4+/-39.8, residual urine (ml) before - 459+/-99.4, after - 50+/-11.8. Detrusor tone (rel. units) before - 0.6+/-1.5, after 1.2+/-0.2; voiding pressure (cmH(2)O) before - 4.4+/-5.2, after - 30.5+/-4.9. Force of detrusor contraction before - 5+/-5.8, after - 32.8+/-5.5. Sphincter resistance (cmH(2)O) before - 6.5+/-3.8, after - 21.1+/-4.2. Significant improvements in bladder function were observed during the 10th to 12th postoperative months. Restoration of reflex voiding occurred in all patients; in eight of the 11 paresthesic in the groin and scrotum and reappearance of the bulbocavernous, anal and cremasteric reflexes were noted. CONCLUSION: These results suggest that a restitutive process occurs in the bladder under novel conditions of its nerve supply provided by the intercostal nerve and by new connections established between it and the bladder nerves. Spinal cord lesions that might benefit from nerve crossover surgery would be located at the conus, so functional intercostal nerves could be connected to sacral roots to bypass the injury in an attempt to restore central connections to the bladder.

The role of radiofrequency in the treatment of mechanical pain of spinal origin.

Radiofrequency (RF) ablation is a method that has been gaining popularity over the past few years among spinal surgeons. It has a role when dealing with pain of spinal origin, either mechanical or neuropathic, after conservative treatment has failed. In the present study, 122 patients with a minimal follow up of 1 year were examined at our institution after having undergone RF heat lesion of the medial branch for mechanical spinal pain (low back pain, thoracic pain or cervical pain). They were followed up 1, 3, 6 and 12 months after treatment. Twenty-two of them were additionally followed up at 18 months. After 1 month, 91 patients (75%) were satisfied with the results. After 3 months, 87 patients (71%) had significant pain relief, while in 35 patients (29%) there was no improvement. After 6 months of follow-up, 80 patients (66%) had pain relief and in 42 patients (34%) there was no effect. At 12-months follow-up, 77 patients (63%) showed good results and 45 patients (37%) had no effect. In the case of the 22 patients who were followed for 18 months, all showed significant pain relief. Minor complications occurred in 27 patients (22%), who had transient discomfort and burning pain. We concluded that RF is a safe and partially effective procedure for mechanical back pain.

Effects of GnRH administered to cows at the onset of estrus on timing of ovulation, endocrine responses, and conception.

Two experiments examined effects of GnRH administered within 3 h after onset of estrus (OE) on ovulation and conception in dairy cows. In experiment 1, 46 cows received either saline, 250 microg of GnRH, or 10 microg of the GnRH analogue, Buserelin. Cows were observed for estrus, blood samples were collected, and ovulations were monitored by ultrasound. In controls, 76% of cows had intervals from estrus to ovulation of < or = 30 h and 24% had intervals > 30 h. Treatment with either GnRH or GnRH analogue (data combined) increased magnitude of LH surges and decreased intervals from estrus to LH surge or to ovulation. Treated cows all ovulated < or = 30 h after OE. Among control cows, plasma estradiol concentrations before estrus correlated positively with amplitudes of LH surges. Higher plasma progesterone was observed in the subsequent estrous cycle in GnRH-treated cows compared to control cows with delayed ovulations. Experiment 2 included 152 primiparous and 211 multiparous cows in summer and winter. Injection of GnRH analogue at OE increased conception rates (CR) from 41.3 to 55.5% across seasons. In summer, GnRH treatment increased CR from 35.1 to 51.6%. Across seasons, GnRH increased CR from 36.0 to 61.5% in cows with lower body condition at insemination and GnRH increased CR (63.2 vs. 42.2%) in primiparous cows compared to controls. Use of GnRH eliminated differences in CR for cows inseminated early or late relative to OE and increased CR in cows having postpartum reproductive disorders. In conclusion, GnRH at onset of estrus increased LH surges, prevented delayed ovulation, and may increase subsequent progesterone concentrations. Treatments with GnRH increased conception in primiparous cows, during summer, and in cows with lower body condition.

Harvesting bone graft from the posterior iliac crest by less traumatic, midline approach.

Complications of the donor site after the harvest of corticocancellous bone graft from the posterior iliac crest are very common. The most common are chronic donor site pain, tenderness, and sensory disturbances. This study investigates the results of the midline, lumbar fascia splitting approach for harvesting bone graft in lower lumbar spine fusion and compares them with the classic separate incision approach. A retrospective study of 107 patients compares two groups. The first group of 56 patients (35 males and 21 females with an average age of 41.8 years) had bone graft taken by splitting the two layers of the lumbar fascia down to their attachment to the iliac crest. The second group of 51 patients (29 males and 22 females with an average age of 43.7 years) had a separate incision over the iliac crest. In the first group, 82.1% had no tenderness, 8.9% mild, 7.1% moderate, and only 1.8% severe tenderness over the donor site. In the second group, 45.1% had no tenderness, 21.6% mild, 17.6% moderate, and 15.7% severe tenderness over the donor site. Five patients of the separate incision group (9.8%) had a lump in the donor site compared with none in the "same incision" group. Sensory disturbances over the donor site were found in 5.4% of the first group and in 21.6% of the second group. Harvesting bone graft from the posterior iliac crest for lower lumbar spine fusion through a midline, fascia splitting approach was found superior to the traditional, separate incision approach.

Seasonal differences in progesterone production by luteinized bovine thecal and granulosa cells.

This study examined seasonal differences in progesterone (P4) production by granulosa cells (GC) and thecal cells (TC) that were luteinized in vitro during the winter or the summer; it also compared plasma P4 concentrations of lactating dairy cows in the two seasons. First-wave dominant follicles obtained from Holstein cows were dissected on day 6 of the cycle, GC and TC were separated, enzymatically dispersed, and cultured for 9 days in media containing 1% fetal calf serum, forskolin (10 micromol/mL) and insulin (2 microg/mL), to induce cell luteinization. All experimental procedures were identical and characteristics of the follicles were similar in the two seasons. During 9 days of culture, P4 production by luteinized GC was higher in winter than in summer, but the difference only tended to be significant. In contrast, luteinized TC produced three times as much P4 in winter as in summer (324 versus 100 ng/10(5)cells). In the in vivo experiment, P4 concentrations in plasma collected during entire estrous cycles in winter and summer were compared. The cows were, on average, at 70 days postpartum and yielded similar amounts of milk. Concentrations of progesterone in plasma were significantly higher in winter than in summer; during the mid-luteal phase the difference between the two seasons was 1.5 ng/mL. These results indicate that chronic effects of heat-stress are possibly carried over from an impaired follicle to an impaired corpus luteum (CL), and that luteinized TC are more susceptible to heat-stress than luteinized GC.

Delayed effect of low progesterone concentrations on bovine uterine PGF(2alpha) secretion in the subsequent oestrous cycle.

Low progesterone concentrations during the bovine oestrous cycle induce enhanced responsiveness to oxytocin challenge late in the luteal phase of the same cycle. The delayed effect of low progesterone concentrations during one oestrous cycle on uterine PGF(2alpha) secretion after oxytocin challenge on day 15 or 16 of the subsequent cycle was studied by measuring the concentrations of the major PGF(2alpha) metabolite (13,14-dihydro-15-keto PGF(2alpha); PGFM) in plasma. Two experiments were conducted, differing in the type of progesterone treatment and in the shape of the low progesterone concentration curves. In Expt 1, progesterone supplementation with intravaginal progesterone inserts, with or without an active corpus luteum, was used to obtain high, or low and constant plasma progesterone concentrations, respectively. In Expt 2, untreated cows, representing high progesterone treatment, were compared with cows that had low but increasing plasma progesterone concentrations that were achieved by manipulating endogenous progesterone secretion of the corpus luteum. Neither experiment revealed any differences in plasma progesterone concentrations between the high and low progesterone groups in the subsequent oestrous cycle. In both experiments, both groups had similar basal concentrations of PGFM on day 15 (Expt 1) or 16 (Expt 2) of the subsequent oestrous cycle, 18 days after progesterone treatments had ended. In both experiments, the increases in PGFM concentrations in the low progesterone groups after an oxytocin challenge were markedly higher than in the high progesterone groups. These results indicate that low progesterone concentrations during an oestrous cycle have a delayed stimulatory effect on uterine responsiveness to oxytocin during the late luteal phase of the subsequent cycle. This resulting increase in PGF(2alpha) secretion may interfere with luteal maintenance during the early stages of pregnancy.

Effects of somatotropin and dietary calcium soaps of fatty acids in early lactation on milk production, dry matter intake, and energy balance of high-yielding dairy cows.

We allocated 39 high-yielding individually fed cows to three treatments: control, calcium soaps of fatty acids (CSFA) fed at 2.2% dry matter, and 500 mg of Zn-sometribove (bST) injected every 14 d from 10 to 150 d in milk (DIM). Production of fat corrected milk was increased by 3.0 kg/d in the CSFA group and by 5.4 kg/d in the bST group. Energy balance was negative during the first 28 to 34 DIM in control and CSFA cows and during 59 DIM in bST-treated cows; minimum body weight, minimum body condition score, and DMI peak were reached 25-28 d later in the bST group. Dry matter intake (DMI) was significantly increased by bST, and during the first 3 wk of treatment the increase in DMI of the bST cows was 46% more than that of the controls. DMI was significantly correlated throughout the experimental periods with calculated energy expenditure in the control and CSFA groups, but only during 54 DIM in the bST group. Furthermore, commencement of the DMI decrease was correlated with the beginning of the decrease in milk production. Gross feed efficiency was significantly higher in the bST group than in the other groups. We concluded that treating high-yielding cows with bST early in lactation increased milk production at the expense of an extensive period of negative energy balance and body weight and body condition decreases despite an increase in DMI after bST treatment.

Two methods of inducing low plasma progesterone concentrations have different effects on dominant follicles in cows.

The effects of two methods of inducing low progesterone concentrations on the shape of the plasma progesterone curve and on follicular characteristics in lactating cows were studied. A low ascending progesterone curve was elicited by three PGF2alpha injections on d 3 to 4 of the estrous cycle; a low constant curve by induction of corpus luteum regression on d 6 and insertion of two progesterone-containing intravaginal devices from d 6 to 15 of the cycle. Plasma progesterone concentration was highest in the untreated control group, intermediate in low ascending group, and lowest in the low constant group. On d 15, both control and low ascending groups had one large healthy and one large atretic follicle, suggesting a turnover of follicular waves; in the low constant group, the presence of only one very large healthy follicle indicated follicular persistence. Estradiol concentration in the follicular fluid and its production by granulosa cells were highest in the low constant, intermediate in the low ascending, and lowest in the control group. Androstenedione concentration in the follicular fluid and its production by theca cells were higher in the low constant than in the low ascending and control groups. The results indicate that the low ascending progesterone curve affected follicular development and steroidogenesis differently from the low constant curve. We suggest that the low ascending curve mimics the effects of naturally occurring low plasma progesterone concentrations better, and it might, therefore, be used as a model for studying the effects of low plasma progesterone on fertility.

Effect of calcium soaps of fatty acids and administration of somatotropin on milk production, preovulatory follicular development, and plasma and follicular fluid lipid composition in high yielding dairy cows.

The effect of fat and bovine somatotropin (bST) on preovulatory follicular hormones and lipids was evaluated by feeding cows for 150 d from parturition a control diet, a control diet plus 0.55 kg/d of calcium soaps of fatty acids, or a control diet with 500 mg of bST injected every 14 d. Fourteen days after a synchronized or natural estrus, cows were injected with a PGF2 alpha analogue; 48 h later, follicular fluid from all ovarian follicles > 8 mm was aspirated. Cows fed fat or injected with bST produced more milk and milk solids than did control cows, and cows on the bST treatment lost more body condition after calving than did cows on the other treatments. Both treatments changed the proportion of estradiol-active follicles (> 400 ng of estradiol/ml of follicular fluid) and the correlation between follicular fluid estradiol concentration and the total number large follicles per cow. In follicles aspirated between 60 and 90 DIM the percentage of estradiol-active follicles was 67, 40, and 0 for cows on the control, calcium soaps of fatty acids, and bST treatments, respectively. After 90 DIM, no differences existed between treatments in the percentage of estradiol-active follicles. Estradiol concentration in follicular fluid was correlated with DIM at follicle aspiration (r = 0.51). The proportion of oleic acid in free fatty acids in plasma at 50 DIM was lower in control cows and was lower in follicular fluid of estradiol-active follicles. Both calcium soaps of fatty acids and bST had a considerable effect on follicular development and activity and the composition of fatty acids in follicles.

The effect of enhanced milk yield of dairy cows by frequent milking or suckling on intake and digestibility of the diet.

Groups of 9 or 10 cows were assigned to one of three treatments 1) machine-milking three times daily, 2) machine-milking six times daily, and 3) suckling three times daily in addition to machine-milking three times daily. Treatments were conducted during the first 6 wk postpartum. During wk 5, digestibility of the diet was estimated by the indigestible neutral detergent fiber method. During wk 6, milk yield and dry matter intake (DMI) were recorded daily, and plasma concentrations of glucose, nonesterified fatty acids, urea, protein, growth hormone, insulin, insulin-like growth factor I, oxytocin, and prolactin were determined. Milk yields were 38.5, 46.8, and 52.7 kg/d, and DMI were 18.1, 21.2, and 17.2, for cows on treatments 1, 2, and 3, respectively. Plasma glucose concentrations decreased, and plasma nonesterified fatty acid concentrations increased, for cows on treatments 2 and 3 compared with cows on treatment 1. Digestibility of dry matter was 57.5, 60.5, and 60.6%; of organic matter was 62.6, 64.6, and 66.8%; and of crude protein was 59.3, 62.7, and 64.6% for cows on treatments 1, 2, and 3, respectively. Concentrations of all assayed hormones, except insulin, increased moderately for cows on treatment 2 compared with cows on treatment 1 and increased dramatically for cows on treatment 3. Insulin concentrations followed the opposite trend. The DMI were positively related to milk yields and negatively related to oxytocin concentrations. Digestibility was negatively related to plasma glucose concentrations in a nonlinear pattern. The possible involvement of hormones in improvement of digestibility is discussed.