S. Chadio

Reduced Sertoli cell number and altered pituitary responsiveness in male lambs undernourished in utero

The nutritional status of females during pregnancy can have profound effects on the fetus reproductive system development that could affect the reproductive potential as later as in adulthood (fetal programming). The aim of the present study was to examine the effects of maternal nutrient restriction imposed during different periods of gestation on pituitary responsiveness at different ages postnatal and on Sertoli cell number in male offspring. Pregnant ewes were fed to 100% of Metabolizable Energy and Crude Protein requirements throughout pregnancy (Control) or to 50% from 0 to 30 (R1) or from 31 to 100 days of gestation (R2). Male lambs were selected and fed to appetite throughout the study. At 2, 5.5 and 10 months of age a GnRH challenge was conducted. At slaughter (10 months) testes were removed and examined histologically. Maternal undernutrition did not affect the time of the onset of puberty, defined as the first increase in plasma testosterone concentrations > or =1 ng/ml. The LH and FSH response to GnRH challenge did not differ between groups at 2 and 5.5 months but at 10 months of age a higher (P<0.05) FSH response was found in R2 group. Testes weight did not differ between groups at slaughter. Mean Sertoli cell number was significantly lower in animals of R2 group compared with Control (P<0.01). A smaller seminiferous tubules diameter was detected in R2 group (P<0.05), while the diameter of the lumen was similar in all groups. Collectively, these results provide clear evidence for a direct effect of nutrient restriction during pregnancy on Sertoli cell number in adulthood. The lower number of Sertoli cells is the most candidate factor for the higher pituitary activity through a reduction in the suppressive effect of inhibin.

Endocrine events during the periestrous period and the subsequent estrous cycle in ewes after estrus synchronization.

The aim of the present study was to investigate the endocrinology of the periestrus period and that of the subsequent estrous cycle in ewes synchronized during the breeding season. Animals were treated for 14 days with either MAP intravaginal sponges or subcutaneous progesterone implants, followed by administration of 500 IU PMSG at the time of withdrawal. The time to estrus occurrence following progestagen withdrawal differed significantly between groups (45.3+/-2.7h for the MAP and 21.5+/-1.2h for the implant group, P<0.001). Estradiol levels around estrus did not differ between groups, but a significant difference was detected for the interval from peak estradiol to estrus, with a shorter interval for the implant group (26.7+/-0.7 and 2.7+/-0.9h, P<0.001). Progesterone implants shortened the interval from removal to LH surge, compared to the MAP group (31.2+/-4.4 and 56.5+/-3.6h, respectively, P<0.05). An earlier response was also observed for the interval from estradiol peak to LH peak in the implant group (12.1+/-3.3 and 37+/-2h, respectively, P<0.005), but no difference was observed for the interval from estrus to LH surge. Progesterone levels, particularly during the Days 6 to 10 of the subsequent estrous cycle were significantly higher (P<0.05) in the implant group. It is concluded that the kind of progesterone treatment may affect the time of estrus and the LH peak as well as the progesterone levels of the subsequent cycle.

Selenoenzyme activities in selenium- and iodine-deficient sheep

This study was conducted to evaluate the effects of single and combined deficiencies of selenium and iodine on selenoenzyme activities in sheep. Twenty-four male lambs were assigned to one of four semisynthetic diets: combined deficient A (Se−I), Se-deficient B (Se−I+), I-deficient C (Se+I−), and basal diet D (Se+I+). Thyroid hormones (T3, T4), thyroid stimulating hormone (TSH), and inorganic iodine (PII) were determined in plasma. Selenium and glutathione peroxidase activity (GSH-Px) were determined in erythrocytes, and tissue samples, including the thyroid, liver, kidney, and brain, were taken for selenoenzyme analysis. Plasma T3, T4, and TSH concentrations were similar in all groups. Type I deiodinase (ID-I) activity in liver and kidney remained unchanged in Se or I deficiency. In contrast, hepatic ID-I activity was increased by 70% in combined Se-I deficiency. Thyroidal cystolic GSH-Px (c-GSH-Px) and phospholipid GSH-Px (ph-GSH-Px) activities remained constant in both Se-deficient groups, whereas thyroidal c-GSH-Px activity increased (57%) in I deficiency. Type II deiodinase (ID-II) activity was not detectable in the cerebrum and cerebellum, whereas cerebellum Type III deiodinase (ID-III) activity was decreased in I deficiency and combined Se-I deficiencies. The results of the present study support a sensitive interaction between Se and I deficiencies in sheep thyroid and brain. Furthermore, the lack of thyroidal ID-I activity, the presservation of the thyroidal antioxidant enzymes, and the increases in hepatic ID-I indicate that a compensatory mechanism(s) works toward retaining plasma T3 levels, mostly by de novo synthesis of T3 and peripheral deiodination of T4 in Se- and I-deficient sheep.

Studies on stress responses and recovery from removal in gilthead sea bream Sparus aurata (L.) using recirculated seawater system

The effects of serial cohort-removal stress on physiological responses in immature specimens of the euryhaline species, the gilthead sea bream Sparus aurata, were investigated (trial 1). In addition, physiological responses during recovery in tanks of 175 l (10.5 kg/m3) after a single (trial 2) or serial (trial 3) cohort-removal from a holding tank of 1 m3 (14 kg/m3) were examined. All trials were performed in a recirculated seawater system. Serial cohort-removal for 90 min, combined with a continuous pursuing (trial 1), caused a significant increase of plasma cortisol, glucose, osmolality, Na+, Cl− and pCO2, and a significant reduction of pH, K+ and HCO3− in the remaining fish of the holding tank. These alterations in most of the plasma parameters studied were progressive for 45–60 min and then remained almost constant. When undisturbed fish were netted and transferred (trial 2), the levels of plasma cortisol, glucose, osmolality, Cl− and Na+ initially increased, exhibiting maximum elevations at 40 min and recovering within 2 h. At the end of a serial cohort-removal after 15 min, without chasing the fish (trial 3), the levels of plasma cortisol, glucose, Na+, Cl− and K+ did not significantly differ from the control levels. However, during recovery from netting and transfer of fish disturbed by this serial cohort-removal, the levels of plasma cortisol and glucose recovered after 5 h. It is indicated that serial cohort-removal, depending on its duration, may increase the alterations in stress responses, especially the secondary ones, and prolong the extent of cortisol and glucose elevations. It was concluded, that serial cohort-removal of gilthead sea bream should be mild and short-term and could be repeated the same day allowing, however, a sufficient period for cortisol and glucose recovery.

Pituitary responsiveness to GnRH in lambs undernourished during fetal life

Abstract A study was conducted to investigate the effect of undernutrition in utero on pituitary responsiveness to GnRH stimulation in lambs after birth. Thirty-four lambs were used which were born to ewes fed 110% of the energy maintenance plus two embryos requirements during pregnancy (control, C) or 90% of the maintenance with no additional allowances for embryo growth (restricted, R) from 30 day of pregnancy to lambing. A GnRH stimulation test was performed on all lambs at 55 days of age. The average energy consumed daily by each ewe in the R group was only the 60% of that consumed by the ewes in the C group. Following injection of GnRH, peak LH values were observed within 15 min in both groups. Animals in Group C (n = 19) showed a significantly greater LH response than animals in Group R (n = 15) at 15 min and at 30 min post-injection (43.3 vs. 33.9 and 39.0 vs. 32.2 ng ml−1, respectively). The significant treatment × time interaction found revealed that the rate of increase of LH concentration above the basal value within the first 15 min after GnRH administration was higher in C than in R lambs, while the rate of decrease from 30 to 120 min was lower in R than in C lambs. It was concluded that the timing as well as the magnitude of maternal undernutrition may be significant factors affecting the subsequent reproductive potential of the progeny in sheep by reducing pituitary activity.

Effect of selenium supplementation on thyroid hormone levels and selenoenzyme activities in growing lambs

The aim of the present study was to evaluate the effects of selenium supplementation on thyroid hormone metabolism and selenoenzyme activities in lambs. Twelve 20-d-old male lambs were assigned to one of two diets: A (0.11 ppm Se) and B (supplemented with 0.2 ppm selenium as sodium selenite). Blood samples were collected weekly for the determination of T3, T4, and selenium levels. The response to thyrotropin-releasing hormone (TRH) challenge was estimated at the 11th and 20th wk. Animals were slaughtered at wk 20 and tissues were collected for enzyme determination. Plasma selenium concentration was significantly higher in supplemented lambs (p<0.001). Plasma T3 and T4 levels remained similar in both groups. Type I deiodinase activity (ID-I) was decreased in the liver (p<0.05) and increased in the pituitary (p<0.01) of supplemented animals. No ID-I activity was detected in the thyroid. Pituitary type II deiodinase activity (ID-II) remained unchanged. The response to TRH challenge did not differ between the two groups for both challenges, but in group B, the second TRH challenge (20th wk) resulted in a significantly higher T3 response compared to the first one (11th wk) (p<0.05). In conclusion, the lack of effects of Se supplementation on thyroid hormone metabolism demonstrates that enzyme activity is homeostatically controlled and selenium is incorporated in that order to ensure the maintenance of thyroid hormone homeostasis.

Growth and physiological changes in scaled carp and blue tilapia under behavioral stress in mono- and polyculture rearing using a recirculated water system

Growth performance, carcass composition, liver and blood parameters ofscaled carp (C), Cyprinus carpio, and blue tilapia (T),Oreochromis aureus, reared for eight weeks in twomonoculture (100%C and 100%T) and two polyculture (60%C–40%T and40%C-60%T) conditions were investigated. In polyculture 40%C–60%T bothspecies achieved the highest levels of specific growth rate and the lowestlevels of food conversion ratio and carcass lipid content. In addition, theyexhibited the highest values of plasma pO2 and pH and the lowestvalues of plasma pCO2, cholesterol and albumin, although thedifferences among treatments were not significant in the case of tilapia.Tilapia showed significantly lower plasma Cl− levels than underthe other conditions. Carp in monoculture and tilapia in polyculture60%C–40%T had the lowest levels of specific growth rate and significantlyhigher levels of liver lipids and plasma triglycerides than in the other groups.In addition, carp in monoculture exhibited a significantly higher haematocritthan in polyculture. No significant variations among treatments were observedconcerning plasma cortisol, glucose, osmolality, Na+, K+,HCO3− andHCO3−/H2CO3 in either species.The combination of scaled carp and blue tilapia, in which blue tilapia were themain species, proved to be the best for both species. It was suggested thatgrowth and physiological changes under mono- and polyculture rearing, in anintensive system, seem to be as a result of a different state of stress relatedto fish behavior.

Progesterone levels throughout progestagen treatment influence the establishment of pregnacy in the goat

Abstract Estrus synchronization was induced in Saanen goats during the breeding season by insertion of intravaginal sponges (60 mg medroxyprogesterone acetate) for 17 d followed by intramuscular injection of 500 IU PMSG 2 d before sponge withdrawal. Artificial insemination was performed at 24 and 48 h after sponge removal. Serum progesterone levels were measured throughout the treatment period and the subsequent estrous cycle. Mean progesterone concentrations were significantly different during the period with the progestagen treatment between animals that conceived (Group 1) and those that failed to conceive (Group 2, 3.7 ± 0.3 and 2.02 ± 0.2 ng/ml,respectively, mean ± SEM; P

Early pregnancy diagnosis in swine by direct radioimmunoassay for progesterone in blood spotted on filter paper

A direct radioimmunoassay method for the measurement of progesterone in blood dried on filter paper has been developed for the early pregnancy diagnosis in sows, as well as for monitoring progesterone levels during the oestrous cycle. Pregnancy diagnosis was performed with 95 sows on Days 17-22 after artificial insemination (AI). The cut-off value for pregnancy diagnosis of 7.5 ng/ml was calculated (mean+/-2S.D.) from the progesterone concentrations measured on the same days from non-inseminated animals. There were 85 cases considered pregnant on the basis of progesterone concentration, leaving 10 animals non-pregnant. The accuracy for the positive cases was 98.8%. Two of the 10 sows considered as negative subsequently farrowed, giving an accuracy of 80%. The overall accuracy of the method was 96.8%. The blood-spot assay may be a useful tool for early pregnancy diagnosis in swine, with respect to sampling, simplicity, speed and accuracy.

Effects of Gestational Maternal Undernutrition on Growth, Carcass Composition and Meat Quality of Rabbit Offspring

An experiment was conducted in order to evaluate the effects of gestational undernutrition of rabbit does on growth, carcass composition and meat quality of the offsprings. Thirty primiparous non lactating rabbit does were artificially inseminated and randomly divided in three treatment groups: Control (C; fed to 100% of maintenance requirements throughout gestation, n = 10), early undernourished (EU; fed to 50% of maintenance requirements during days 7–19 of gestation, n = 10) and late undernourished (LU; fed to 50% of maintenance requirements during days 20-27 of gestation, n = 10). During the 4th week of the gestation period, LU does significantly lost weight compared to C and EU groups (P<0.05). At kindling, C does produced litters with higher proportions of stillborn kits (P<0.05) while the total litter size (alive and stillborn kits) was not different among groups (10.7, 12.8 and 12.7 kits in C, EU and LU groups, respectively). Kit birth weight tended to be lower in the LU group. During fattening, body weight and feed intake were not different among offsprings of the three experimental groups. Moreover, the maternal undernutrition did not have any impact on carcass composition of the offsprings in terms of carcass parts and internal organs weights as well as meat quality of L. lumborum muscle (pH24, colour, water holding capacity and shear values) at slaughter (70 days of age). Therefore, it can be concluded that the gestational undernutrition of the mother does not have detrimental effects on the productive and quality traits of the offsprings.