Ampicillin tolerance and content in the mammary gland of lactating cows and sheep

Experiments were carried out with lactating cows and ewes consisting in the intramammary application of ampicillin-trihydrate with the use of syringe cannules, and with paraffin and vaselin as constituents. Cows were treated with 10 cm3 (500,000 IU) (in the respective quarter of the udder), and ewes--with one half of the syringe content. The milk of the treated animals was sampled prior to manipulation, at the 24th, the 48th, 72nd and 96th hour in order to follow up the time during which the antibiotic was retained in the milk as well as the changes in the cell content and the hydrogen ion concentration. It was found that ampicillin persisted in milk up to the 48th hour in therapeutic concentrations. At the 96th hour the milk proved free of the antibiotic in both cows and ewes and could be offered for consumption or technologic processing.     

Effect of oestradiol on ovarian oxytocin secretion rate and luteolysis in the ewe after ovarian auto-transplantation

The release of ovarian oxytocin and uterine prostaglandin (PG)F2alpha in response to an oestradiol stimulus was investigated. On Day 15 post-oestrus, ten ewes with ovarian auto-transplants (n=5 per group) received an intra-muscular injection of either oestradiol benzoate (50 microg) or vehicle. Blood samples were collected from the ovarian and jugular veins at 30 and 0 min before, and at 15-min intervals up to 540 min after, injection. The secretion rate of ovarian progesterone remained elevated in four of five treated ewes and in all control ewes, indicating the presence of a functional corpus luteum. Peripheral oestradiol concentrations were significantly (P < 0.001) higher in treated than in control ewes. The number of ewes that released pulses of ovarian oxytocin > or =240 min following oestradiol benzoate injection was significantly (P < 0 05) greater than that in control ewes. Mean amplitude and area under both ovarian-vein oxytocin and jugular-vein 15 keto-13,14 dihydro prostaglandin F2alpha (PGFM) pulses were significantly increased in the treated ewes. These findings demonstrate that the administration of exogenous oestrogen provides a positive stimulus for the release of ovarian oxytocin and uterine PGF2alpha in the ovarian auto-transplanted ewe.     

Effects of calcitonin on the secretion of pancreatic juice induced by dopamine, secretin and pancreozymin

Non-lactating, multiparous ewes were immunized either by subcutaneous infection with live Staphylococcus aureus (seventeen ewes) or by intramuscular injections of a killed S. aureus-oil adjuvant vaccine (seventeen ewes). Polymorphs which were subsequently collected from the mammary glands of the animals were used in in vitro phagocytosis assays against Pseudomonas sp. or S. aureus. There was no difference between polymorphs from the two groups of ewes in their ability to phagocytose Pseudomonas organisms. Polymorphs from the infected ewes showed significant phagocytic superiority over cells from ewes given the killed vaccine when S. aureus was the target organism. This phagocytic superiority could be abrogated by removal of cytophilic immunoglobulin from polymorphs and restored by replacement of cytophilic immunoglobulin. It was shown by staining polymorphs with FITC-conjugated anti-immunoglobulin sera that cytophilic immunoglobulin on the surface of polymorphs belonged to the IgG2 class of immunoglobulins. When 'neutral' polymorphs (from non-immunized ewes) were coated with IgG2 purified from the sera of infected ewes, they exhibited enhanced phagocytosis of staphylococci compared with 'neutral' polymorphs carying IgG2 from the sera of ewes given the killed vaccine.     

Net flux of glucose, lactate, volatile fatty acids, and nitrogen metabolites across the portal-drained viscera and liver of pregnant ewes

Our objective for this study was to determine the pattern of nutrient flux across the portal-drained viscera (PDV) and liver in ewes with varying numbers of fetuses. Catheters were placed in the hepatic portal vein, a branch of the hepatic vein, a mesenteric vein, and the abdominal aorta of ewes. Blood flow and net nutrient release across the PDV and liver were determined before exposure to rams. Ewes were then mated, which resulted in two ewes not pregnant and in six ewes with single and 11 ewes with twin lambs. Additional measurements were taken 103, 82, 61, 39, 19, and 6 d before parturition. Net PDV glucose release did not differ from zero (-.4 +/- 8.4 mmol/h; P = .58). In ewes with singles, premating net hepatic glucose release was 34.4 +/- 2.4 mmol/h, and 19 d before parturition it was 46.2 +/- 3.8 mmol/h. In ewes with twins, premating net hepatic glucose release was 36.8 +/- 2.7 mmol/h, and 19 d before parturition it was 47.4 +/- 2.8 mmol/h. Net PDV lactate release did not differ with litter size (P = .58) or days from parturition (P = .14; 9.7 +/- 4.6 mmol/h). Net lactate uptake by the liver increased in pregnant ewes as the pregnancy progressed (P < .001). The hepatic extraction ratio for lactate increased in late pregnancy (P = .02). Net PDV and hepatic release of acetate and propionate were not different with litter size or days from parturition. Hepatic extraction ratios of VFA did not differ with litter size or day from parturition. The patterns of change in hepatic metabolite fluxes are similar to the patterns of change in gravid uterus metabolite uptake. Hepatic lactate uptake seems to be regulated during pregnancy.     

Effect of prepartum bovine somatotropin in primigravid ewes on mammogenesis, milk production, and hormone concentrations

Twenty-five primigravid ewes were used to investigate the effect of bST, between 97 and 124 d of gestation, on mammogenesis and subsequent milk production. Five ewes (reference group) were slaughtered at 96 d of gestation, and the remaining ewes were injected daily with saline (control group: n = 10) or .1 mg/kg of BW of bST (bST group: n = 10). Following bST treatment, 5 control and 5 bST group ewes were slaughtered (slaughter group). The remaining ewes were slaughtered after lambing and being milked for 8 wk (production group). Weekly blood samples were obtained from both slaughter and production group ewes. Slaughter group ewes were also subjected to 8-h serial blood sampling at 98 d (period 1) and 123 d (period 2) of gestation. Milk production was 42% higher in ewes treated prepartum with bST than in those treated with saline. Results suggest that the increase in milk was due to an increase in mammary parenchymal cell number rather than to an increase in cellular activity. The high rate of [3H]thymidine incorporation into parenchymal tissue in reference group ewes suggests that the increase in parenchyma during the second trimester of gestation is due to cellular hyperplasia but that cellular hypertrophy may be more important during the last trimester. Plasma IGF-I concentrations were significantly higher during bST treatment and remained elevated between daily injections; the increase was greatest in period 2.     

Endocrine and reproductive function in ewes exposed to the organochlorine pesticides lindane or pentachlorophenol

The effects of lindane (LIN, gamma-hexachlorocyclohexane) and pentachlorophenol (PCP) on reproduction and general endocrine function were examined in breeding ewes as a model for wild and domestic ungulates, which may be exposed to low levels of pesticides that are potential endocrine-disrupting chemicals. Ewes (n = 13/group) were fed either a control untreated diet (CON), or a diet treated with LIN (1 mg/kg/d) or PCP (1 mg/kg/d) during the 5 wk prior to mating and throughout pregnancy and lactation. Mating response, ovulation rate, follicle and corpus luteum size, gestation length, pregnancy rate, lambing rate, and lamb birth weight were recorded. After weaning, 6 ewes from each group were bled at 15-min intervals for 8 h during the day and night and for 1 h before and 5 h after i.v. administration of gonadotropin-releasing hormone, thyroid-stimulating hormone (TSH), and adrenocorticotropin, to measure serum concentrations of luteinizing hormone, follicle-stimulating hormone, thyroxine (T4), and cortisol. Ewes were then killed and endocrine tissues examined histologically. Pregnancy rate as a result of matings taking place at the synchronized estrus was significantly decreased by the lindane treatment However, PCP and lindane did not markedly affect any other aspect of reproductive function studied. In PCP-treated ewes, serum concentrations of T4 were significantly reduced compared to control ewes during the day and night; however, the T4 response to TSH was not altered by PCP treatment. No other measured endocrine parameters were consistently affected by lindane or PCP. Thyroid follicle size was significantly increased in the LIN and PCP ewes compared to the control ewes. Low serum concentrations of T4 in the PCP ewes may have resulted in increased TSH secretion and increased thyroid follicle size. In conclusion, although pesticide treatments had no serious adverse effects on reproductive function in breeding ewes, PCP reduced T4 concentration, which in the long term could influence reproductive and general performance.     

Sexual dimorphism of circulating somatotropin, insulin-like growth factor I and II, insulin-like growth factor binding proteins, and insulin: relationships to growth rate and carcass characteristics in growing lambs

The effects of sex and age on patterns of circulating somatotropin (ST) concentration and plasma IGF-I, IGF-II, insulin, and IGF binding protein-3 (IGFBP-3) were studied in ram, wether, and ewe lambs (n = 7 or 8) sampled at mean ages of 81 (I1) and 158 d (I2). Between 81 and 158 d of age, rams grew more rapidly than wethers (P < .01), and wethers grew more rapidly than ewes (P < .01). The sex differences in growth were reflected in empty body weight at slaughter: rams > wethers > ewes (P < .05). Mean plasma ST concentrations, ST pulse amplitude, and integrated plasma ST concentrations were greater (P < .05) in rams than in ewes at I1 and I2. Characteristics of the ST plasma profile in wethers were generally intermediate between those of rams and ewes. The interpulse interval was greater in ewes than in wethers at I2. The IGF-I and IGFBP-3 concentrations were greater in rams than in ewes at both sampling times. Plasma IGF-II was greater in ewes than in rams at I2. Mean plasma ST was approximately two thirds less at I2 than at I1 regardless of sex. Mean plasma ST and IGF-I at both ages were positively correlated with growth. Mean plasma ST at I2 was negatively correlated with fatness at slaughter. Sex and age significantly affected patterns of circulating ST and concentrations of IGF-I and IGFBP-3 in prepubertal growing lambs, under conditions for which growth rates and composition were also sexually dimorphic.     

Influence of maternal bodyweight on size, conformation and survival of newborn lambs

Although body condition score was not significantly different between light (<55 kg, n = 6) and heavy (> or =60 kg, n = 7) ewes at mating, it declined between Day 30 and Day 90 of gestation in light but not heavy ewes, and remained lower up to term. All ewes bore twins, delivered near term (Days 144-146) by Caesarean section. One lamb was immediately placed into a warm (30 degrees C; WD) and its twin into a cool (15 degrees C; CD) ambient temperature, and tissues were sampled at 0.5 h or 6 h. All CD lambs born to light ewes exhibited hypothermia and/or respiratory failure and did not survive longer than 30 min; these symptoms were not observed in their WD twins or any lamb born to heavy ewes. Total lamb birth weight, placental weight and fetal cotyledonary weight were lower with light than with heavy ewes. Lambs born to light ewes had less perirenal adipose tissue and smaller liver, heart, kidneys, brain, adrenals and thyroid, although their heart, brain and pancreas represented a larger proportion of total bodyweight; pancreas weight was similar to that in lambs born to heavy ewes. Hence, maternal bodyweight critically influences placental weight and lamb size and survival after birth.     

Effects of exogenous recombinant ovine interferon tau on circulating concentrations of progesterone, cortisol, luteinizing hormone, and antiviral activity; interestrous interval; rectal temperature; and uterine response to oxytocin in cyclic ewes

Interferon tau (IFN tau) is the conceptus-produced antiluteolytic signal in ruminants. Three experiments examined the effects of s.c. administration of recombinant ovine (ro)IFN tau on interestrous interval (IEI), oxytocin (OT)-induced uterine prostaglandin F2alpha metabolite (PGFM) production, rectal temperature (RT), respiration rate (RR), and plasma concentrations of progesterone, cortisol, LH, and antiviral activity (AVA) in plasma and uterine flushings. In experiment I, 20 ewes were treated s.c. with either 0, 1, 2, or 4 mg/day roIFN tau (0.7 x 10(8) U/mg; 5 ewes/dosage) from Days 11 to 15 of the estrous cycle (estrus = Day 0) and were challenged with OT (30 IU) on Day 15. Jugular blood samples were collected at -10, 0, 10, 20, 30, 40, 50, and 60 min relative to the OT challenge and assayed for PGFM. Recombinant oIFN tau increased IEI (16.7, 18.7, and 22.6 +/- 0.6 days for 0, 2, and 4 mg roIFN tau, respectively, p < 0.01). Recombinant oIFN tau did not affect peak PGFM response to OT (2309 +/- 172 pg/ml; p > 0.1). However, the 4 mg/day dosage delayed the time to peak PGFM (32.4 vs. 47.5 +/- 3.4 min; p < 0.01, 0 vs. 4 mg) and resulted in approximately 200% higher concentrations of PGFM at 60 min post-OT (0 vs. 4 mg/day, p < 0.07). Experiment II was similar to experiment I, except that only the 0- and 4-mg/day dosages of roIFN tau were administered. Ewes were hysterectomized on Day 16, and assay of uterine flushes detected no AVA from ewes treated with either 0 or 4 mg/day roIFN tau. In experiment III, 20 ewes were treated s.c. with either 0, 2, 4, or 6 mg roIFN tau on Day 12. Blood samples, RT, and RR were obtained at frequent intervals for 24 h, and plasma was assayed for progesterone, cortisol, LH, and AVA. Plasma AVA, which increased in a dose-dependent manner, was detectable within 60 min and remained elevated at 24 h compared to control values. RT (elevated 0.5-1.0 degrees C), RR, and cortisol increased in response to all dosages of roIFN tau, with peak values occurring 150-180 min postinjection. For all dosages of roIFN tau, plasma progesterone declined from 120 to 360 min posttreatment and then returned to pretreatment values by 24 h (p < 0.01) as compared to controls. Overall, exogenous roIFN tau altered uterine PGFM response to OT from a pulse to a gradual and sustained elevation and extended IEI with only a transient decline in progesterone and mild hyperthermia, effects that are not expected to compromise pregnancy.     

Pregnancy increases soluble and particulate guanylate cyclases and decreases the clearance receptor of natriuretic peptides in ovine uterine, but not systemic, arteries

Pregnancy increases uterine blood flow by 30- to 50-fold and uterine production of cGMP by 38-fold. Moreover, cGMP causes potent vasodilatation. We hypothesized that pregnancy up-regulates soluble and particulate guanylate cyclases (sGC and pGC) in ovine uterine arteries. Activities of sGC and pGC were compared by measuring cGMP production (37 C; 10 min) by uterine arteries from nonpregnant (n = 5) and pregnant (n = 4, 120 +/- 2 days' gestation; term = 145 +/- 3 days; mean +/- SE) ewes after sodium nitroprusside (100 microM), atrial natriuretic peptide (1 microM), or C-type natriuretic peptide (CNP; 1 microM) treatment. The protein and/or messenger RNA expressions of sGC beta1-subunit, pGC-A, pGC-B, the clearance receptor of natriuretic peptide (CR), and CNP were investigated in uterine and systemic (renal and/or omental) arteries from nonpregnant (n = 29) and pregnant (n = 21; 125 +/- 2 days' gestation) ewes. The potencies of uterine arterial GC activities were sGC > pGC-A > pGC-B. Activities as well as protein expression of sGC, pGC-A, and pGC-B in pregnant uterine arteries were increased 48-128% above those in nonpregnant controls concomitant with a 34% down-regulation of CR protein expression; systemic arterial protein expressions were unaltered. These changes in uterine arterial GC-B and CR were confirmed using RT-PCR. Immunohistochemical staining of CNP in uterine, but not systemic, arterial endothelium from pregnant ewes was much stronger than that from nonpregnant ewes. Thus, two distinct GC pathways are present in ovine uterine artery, and both may be specifically upregulated during pregnancy and so contribute to the tremendous local increase in cGMP production during pregnancy.     

Estradiol-17 beta and progesterone increase ovine uterine suppressor cell activity

We evaluated the regulation of ovine uterine (UT) suppressor cell activity by progesterone (P4), estradiol-17 beta (E2), and P4 + E2 in ovariectomized (OVX) ewes. Following 14 d of steroid injections, endometrial cells (designated as UT cells) were recovered postmortem, and unfractionated and fractionated cells were assessed for suppression of autologous phytohemagglutinin (PHA)-treated peripheral blood lymphocytes (PBL). Supernatants from cultured UT cells were also assessed for suppressor activity. In other experiments, UT cells recovered from nontreated OVX ewes were cocultured with PHA-treated PBL and varying concentrations (1 x 10(-11) to 1 x 10(-5) M) of each steroid preparation. Supernatants from separate cultures that contained UT cells and steroids were evaluated for suppressor activity. Uterine cells from control and steroid-treated ewes suppressed proliferative responses of PHA-treated PBL; however, suppressor activity of UT cells was greater (P < .05) for E2-treated than for control and P4-treated ewes. Uterine suppressor cells from steroid-treated ewes sedimented in Percoll within a density range of 1.002 to 1.056 g/mL. Uterine cells from all ewes released suppressor factor(s) into the culture medium; however, the activity of the supernatant from the cultured cells was not increased for the steroid-treated ewes. For cocultures that contained steroids and cultures that contained supernatant, suppressor activity of the UT cells was increased by specific concentrations of each steroid preparation. These findings demonstrate that reproductive steroids augment ovine UT suppressor cell activity.     

High prolificacy in Belle-Ile sheep (Brittany, France): major effects of a putative single gene and the Awh colour gene on ovulation rate and litter size

Ovulation rate (OR) and litter size (LS) were recorded in 72 ewes from a traditional sheep population native to Belle-Ile en Mer, France (BI) from 1986 to 1996. Mean, range and repeatability of OR were: 2.54 +/- 1.1 (n = 494), 1-8 and 0.8, respectively, whereas, for LS, they were: 2.23 +/- 1.0 (n = 146), 1-7 and 0.2, respectively. OR is significantly influenced by age, number of OR, maximum OR in the dam (< or = 3 versus > 3), sire and colour of the fleece (white versus black pattern). OR was also recorded in Charmoise ewes (CH), their F1 progenies with four BI rams and BI ram x F1 backcross ewes (BC). OR range and OR mean in CH ewes, four F1 progenies and BC ewes were: 1-2 and 1.2, 1-2 and 1.2, 1-2 and 1.3, 1-3 and 1.9, 1-4 and 2.3, 1-6 and 2.8, respectively. OR repeatability in CH, F1 and BC were 0.16, 0.45 and 0.71, respectively. The large variation in ovulation rate and litter size combined with high repeatabilities, the familial transmission of a high ovulation rate and the observations in F1 and BC support the hypothesis of a single gene with a large mean effect on ovulation rate and litter size segregating in the population.     

Relationships among ewe milk production and ewe and lamb forage intake in Suffolk and Targhee ewes nursing single or twin lambs

Suffolk and Targhee ewes (30 each) with single or twin lambs were used in four periods beginning in late gestation and continuing through weaning to evaluate breed differences in milk production, lamb BW, and DMI by ewes and lambs. In Periods 1 (late gestation) and 2 (early lactation), ewes (Period 1) and ewes with lambs (Period 2) were individually penned, fed .45 kg of barley x ewe(-1) x d(-1) and allowed ad libitum access to chopped alfalfa. Ewes and lambs grazed native range in Periods 3 and 4. Grazed forage DMI was estimated using chromic oxide. Estimates of milk production were obtained by handmilking. Average lamb age was 4, 45, and 73 d at the beginning of Periods 2, 3, and 4, respectively. Milk production tended (P = .20) to be greater for Suffolk than for Targhee ewes. Targhee ewes produced 85% more (P = .001) wool than Suffolk ewes. From 33 d prepartum to 89 d postpartum, Suffolk ewes consistently weighed more (P = .001) than Targhee ewes. Suffolk ewe BW loss (-.15 kg/d) was greater (P = .01) than Targhee ewe BW loss (-.02 kg/d) from 33 d prepartum to 6 d postpartum. From 6 to 89 d postpartum BW gain did not differ (P = .69; .05 kg/d) between breeds. From birth to 89 d postpartum, Suffolk lambs consistently weighed more than Targhee lambs (P = .003). From birth to 89 d postpartum, ADG was greater for Suffolk than for Targhee lambs (P = .006). Targhee ewes consumed 25% more (P = .01) feed over the course of the study than did Suffolk ewes. Grazed forage DMI by Targhee lambs was 26% greater (P = .01) than DMI by Suffolk lambs. When meat production is the primary income from sheep, one potential advantage of Suffolks compared with Targhees is more rapid gain with less feed intake.     

Reproductive wastage in the androstenedione-immune ewe

An experiment was carried out using 320 adult Merino ewes to examine the effects of immunization against an androstenedione human serum albumin conjugate (Fecundin) on ovulation rate, fertilization rate and embryo viability at days 2, 9 and 13-14 after fertilization. The ovulation rate of immunized ewes (2.19 +/- 0.06) was greater (P < 0.001) than that of control ewes (1.43 +/- 0.04). The recovery rate of embryos or of unfertilized oocytes on day 2 was reduced in immunized ewes, but fertilization rate of recovered oocytes was unaffected by immunization. The mean number of normal embryos per ewe pregnant (prolificacy) was higher and the proportion of ewes pregnant (fertility) was lower in immunized than in the control ewes. The distribution of the number of cells per embryo showed no differences in developmental age over the period of sampling, the majority of embryos at this time being at the two- to four-cell stage of development. At day 9 of pregnancy, blastocyst recovery rates were lower in immunized than in control ewes. About 90% of blastocysts recovered were developing normally in control ewes compared with 64% in immunized ewes. The majority of blastocysts recovered on day 9 had hatched from the zona pellucida prior to recovery (mean values were 94.2% and 87.8% for control and immunized groups, respectively). In control ewes single blastocysts were larger than twin blastocysts, but for the immunized ewes this difference was not significant. Both single blastocysts (P < 0.01) and twin blastocysts (P < 0.05) from immunized ewes were smaller than those from control ewes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oropharyngeal airway dimensions and functional-orthopedic treatment in skeletal Class II cases

Lambs sucking non-immunised ewes or ewes immunised 4-5 weeks before lambing with live attenuated, aromatic-dependent (aroA) Salmonella typhimurium (strain CS 332) were challenged orally at either 2, 4 or 7 days of age with virulent S. typhimurium (strain CS 94) at doses ranging from 10(9) to 10(13) colony forming units. No lambs displayed signs of clinical salmonellosis and all survived challenge but those sucking immunised ewes had organisms of the challenge strain in their faeces for much shorter periods of time than lambs of the control ewes. High titres of specific antibodies were measured in colostrum and milk of immunised ewes in comparison with very low titres measured in samples from control ewes; these differences were reflected by the titres of antibodies in the sera of corresponding lambs. At 2 days after lambing, the major antibody isotype in the colostrum of immunised ewes and sera of their lambs was IgM whereas at 7 days IgG1 was the predominant isotype. While it was clear that vaccination of pregnant ewes with the live attenuated vaccination conferred protection against experimentally-induced salmonellosis in their lambs, considerable protection was observed in control lambs in spite of there being very low titres of antibodies in the mammary secretion of their dams. The latter observation could be related to the presence of contain non-antibody potent bactericidal factors previously described in colostrum and milk.     

Lifetime lamb and wool production of targhee or Finn-Dorset-Targhee ewes managed as farm or range flock: II. Cumulative lamb and wool production

Cumulative lifetime (five lamb crops) lamb production and wool production of 681 ewes were evaluated in this study. Lamb production and wool production from each ewe at the end of age 2, 3, 4, 5, and 6 yr were added to the previous year's production and analyzed within age of ewe. If a ewe failed to lamb, died, or was culled, it received a zero for that year and subsequent years. Main effects in the model included ewe breed and management system. Per ewe entering the study, Finn-Dorset-Targhee (FDT) ewes had a higher (P < .01) number of lambs born (7.42 vs 5.70), number of lambs weaned (5.39 vs 4.48), and total lamb weight weaned (131.7 vs 110.5 kg) than did Targhee ewes. Targhee ewes produced more (P < .01) wool (16.1 vs 13.6 kg) than FDT ewes. Range flock ewes had a higher number of lambs born (6.74 vs 6.38; P < .05), number of lambs weaned (5.39 vs 4.48; P < .01), and total lamb weight weaned (135.8 vs 106.5 kg; P < .01) than did farm flock ewes. Farm flock ewes produced more (P < .01) wool (15.2 vs 14.5 kg). A second analysis based on only those ewes retained at the start of each subsequent breeding season showed FDT ewes had a higher (P < .01) number of lambs born (9.96 vs 8.11), number of lambs weaned (7.61 vs 6.57), and total lamb weight weaned (183.8 vs 165.7 kg) after five lamb crops. Targhee ewes produced more (P < .01) wool (22.5 vs 17.6 kg). Farm flock ewes had a higher (P < .10) number of lambs born (9.18 vs 8.89) and produced more (P < .01) wool (21.1 vs 19.0 kg) than range flock ewes. Range flock ewes weaned more (P < .05) lambs (7.27 vs 6.92) and had more (P < .01) total lamb weight weaned (184.3 vs 165.2 kg) than farm flock ewes.     

Experimental infection of pregnant ewes with Chlamydia pecorum

Pregnant ewes were infected in midpregnancy with three isolates of Chlamydia pecorum derived from the feces of healthy lambs from three different farms. Oral infection, alone or together with Fasciola hepatica, did not result in tissue invasion, since all placental and fecal samples were negative for chlamydiae. Intravenous infection resulted in placental infection in 16 of 18 ewes in that chlamydiae were cultured from placentas or vaginal swabs. Two ewes bore dead lambs after a shortened gestation time. The chlamydiae isolated were all C. pecorum. There were no significant differences between the weights of the lambs from the infected groups and those from uninfected control ewes. Most ewes showed no serological evidence of infection by the complement fixation test; therefore, it is unlikely that the enteric subtype of C. pecorum is responsible for the cross-reactions sometimes seen in flocks being tested for C. psittaci infection.     

Body condition at parturition and postpartum weight gain influence luteal activity and concentrations of glucose, insulin, and nonesterified fatty acids in plasma of primiparous beef cows

Effects of body condition score (BCS) at parturition and postpartum weight gain on luteal activity and concentrations of glucose, insulin, and NEFA in plasma were evaluated during the breeding season in 242 primiparous beef cows over 3 yr (Y) at three locations (L). At approximately 90 d prepartum, cows were blocked by breed, expected calving date, and BCS and randomly assigned to diets so that cows would calve in BCS of 4, 5, or 6. At calving, cows were blocked by breed, calving date, and BCS and randomly allotted to gain .45 (M) or .90 (H) kg/d, from parturition to the start of breeding (postpartum nutrition; PPN). During the 60-d breeding season, weekly blood samples were obtained from cows, and progesterone, insulin, glucose, and NEFA were quantified. Progesterone concentrations greater than 1 ng/mL for more than 1 wk indicated luteal activity. To determine the possible value of blood constituents as predictors of luteal activity, categorical data analyses were performed. Cows with greater BCS at parturition had greater concentrations of glucose during breeding (P < .07). Similarly, PPN influenced glucose at the beginning of breeding, but the differences were minimal after d 28 (PPN x day; P <.001). Cows with greater BCS at parturition and M-PPN had greater concentrations of insulin during the breeding season (BCS x PPN; P < .02). Cows with a BCS of 6 at parturition had the lowest concentrations of NEFA; however, cows on H-PPN had greater concentrations of NEFA (BCS x PPN; P < .03). Location, BCS, PPN, and day affected luteal activity (P < .002). Location differences in luteal activity were associated with the interval from calving to the start of breeding. In general, a greater percentage of cows with BCS of 5 or 6 at calving had luteal activity by the end of the breeding season. Concentrations of metabolites in blood during breeding were not predictive of luteal activity. We conclude that BCS at parturition and postpartum nutrition influence concentrations of glucose, insulin, and NEFA in blood and the onset of luteal activity in primiparous beef cows.     

Asparaginylendopeptidase: an enzyme probably responsible to post-translational proteolysis and transpeptidation of proconcanavalin A

Nineteen ewes were injected subcutaneously with the agent of enzootic ovine abortion, Chlamydia psittaci serovar 1, at 50 days gestation. Placental and fetal tissues were examined at 15 days postinfection and thereafter at ten day intervals. Placental infection was detected at 15 days postinfection. Only postinoculation sera collected from postinfected ewes contained antibodies reactive to C. psittaci. Five (26%) chlamydial infected ewes experienced inapparent fetal loss before day 105 of gestation. This finding is significant since C. psittaci infection in sheep is commonly associated with abortion and not infertility.     

In vivo phosphorylation of phosphofructokinase from the bivalve mollusk Mytilus galloprovincialis

The objective of this study was to determine whether progesterone prevents the stimulatory effects of oestradiol on GnRH receptor gene expression. In Expt 1, ewes were treated during the luteal phase (days 10-12 of the oestrous cycle) with either one or five subcutaneous implants containing oestradiol (n = 6 per group). Control ewes received no treatment (n = 6). Anterior pituitary glands were collected 16 h after treatment with oestradiol. Steady-state amounts of GnRH receptor mRNA were similar among all three treatment groups despite increased circulating concentrations of oestradiol in implanted ewes at the time of pituitary collection (4.3 +/- 0.6 and 24.7 +/- 2.6 pg ml-1 in ewes treated with one or five implants, respectively, compared with 0.5 pg ml-1 in controls). Experiment 2 was designed to determine whether progesterone was the ovarian factor preventing the stimulatory effects of oestradiol on expression of the GnRH receptor gene in Expt 1. Twenty-five ewes were ovariectomized on day 6 or day 7 of the oestrous cycle and assigned to one of five treatment groups (n = 5 per group). Control ewes received no further treatment. Endogenous luteal phase concentrations of progesterone were replaced in three groups of ewes at the time of ovariectomy via intravaginal implants. Three days after ovariectomy, one group of progesterone-treated ewes received one oestradiol implant, while another group of progesterone-treated ewes received five oestradiol implants. An additional group was treated with five oestradiol implants only, and anterior pituitary glands were collected from all ewes 16 h later. Compared with untreated ovariectomized ewes, treatment with progesterone alone did not affect amounts of GnRH receptor mRNA. In ewes treated with progesterone and either one or five oestradiol implants, steady-state amounts of GnRH receptor mRNA were increased twofold (P < 0.01). Treatment with oestradiol in the absence of progesterone increased amounts of GnRH receptor mRNA threefold (P < 0.001). These results provide evidence that the stimulatory effects of oestradiol on the expression of the GnRH receptor gene are prevented during the natural luteal phase in ewes. However, progesterone does not appear to act independently to mediate this effect.