Plasma progesterone concentrations during pregnancy and pseudopregnancy and onset of ovarian activityPost partum in indigenous goats in Zimbabwe

Summary Eight pregnant does were housed individually and fed a hay and concentrate diet throughout pregnancy and lactation. The mean gestation period was 146·7±3·0 days, with a twinning rate of 75 per cent. Mean body condition scores improved from 2·4±0·2 to 2·8±0·2 over the first 80 days of gestation and were maintained at 2·8 until 45 days before kidding. From then until kidding, mean scores fell to 2·2±0·2. Plasma progesterone concentrations during pregnancy rose significantly from 3·91±0·51 ng/ml on day 40 to 5·96±0·51 ng/ml on day 60 (P<0·05) and remained high until 5 days before kidding. Three pseudopregnant does had similar progesterone profiles to pregnant does over the first 80 days, but the rise around day 35 to 40 was not significant and progesterone concentrations returned gradually to basal levels after day 100. The same 8 does, together with an additional 4 does which had been brought inside 60 to 70 days before kidding, were used to study onset of ovarian activitypost partum. The twinning percentage was 83 per cent. Mean body condition score at parturition was 2·2±0·1. By day 35post partum, mean condition scores had fallen to 1·9±0·1, and mean weights from 36·9±1·9 kg at kidding to 32·1±2·0 kg. Ovarian cyclicity was resumed just before mean scores and weights started to improve. The mean interval from kidding to onset of oestrous cycles was 97·3±9·5 days. This coincided with mean time to weaning which was 99·5±5·5 days. It is suggested that suckling and body condition regulate the length of post-partum anoestrus in this species. Season may also play a regulatory role, since does kidding in April to June (n=6) were anoestrus for 82·7±15·0 days compared to 112±7·3 days for does kidding in October to February (n=6), although the difference was not significant.

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Resumen Se, estabularon individualmente ocho cabras pre?adas, dándoles heno y concentrados tanto durante la pre?ez, como durante la lactación. El promedio de gestación fue 146·7±3·0 días, con una tasa gemelar de 75 por ciento. La media de condición corporal, mejoró de 2·4±0·2 a 2·8±0·2 durante los primeros 80 dias de gestación y se mantuvo en 2·8 hasta el día 45 antes del parto, cayendo a 2·2±0·2 de ahí en adelante. La concentración de progesterona en el plasma durante la pre?ez, subió significativamente de 3·91±0·51 ng/ml el día 40 a 5·96±0·51 ng/ml el día 60 (P<0·05), permaneciendo alta hasta 5 días antes del parto. Tres cabras pseudopre?adas tuvieron niveles de progesterona similares a aquellos de las cabras pre?adas, durante los primeros 80 días, pero el aumento alrededor del día 35 a 40 no fue significativo y los niveles de progesterona retornaron gradualmente a los niveles basales, después del día 100. Las mismas 8 cabras, junto con 4 adicionales, que habían sido traídas 60 y 70 días antes del parto, fueron utilizadas para estudiar el inicio pos-parto de la actividad ovárica. El porcentaje gemelar fue de 83 por ciento. La condición corporal media al parto fue de 2·2±0·1. Para el día 35 pos-parto, la condición corporal media había caído a 1·9±0·1; los pesos medios de 36·9±1·9 al parto, cayeron a 32·1±2·0 kg. La ciclicidad ovárica se reanudó un poco después de que la condición corporal y los pesos mejoraron. El intervalo promedio desde el parto hasta el comienzo de los ciclos estrales fue de 97·3±9·5 días. Se sugiere que el amamantamiento y la condición corporal regulan la aparición del estro pos-parto en ésta especie. La estación de parición pueda que juegue un papel importante, debido, a que las cabras que parieron entre abril y junio (n=6), estuvieron en anestro por 82·7±15·0 días, en comparación a 112±7·3 días para las cabras que parieron entre octubre y febrero (n=6), aunque la diferencia no fue estadísticamente significativa.

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Résumé Huit chèvres gestantes ont été gardées à l'étable individuellement et nourries pendant toute la durée de la gestation et de la lactation avec une ration de foin et de concentré. La période moyenne de gestation a été de 146,7±3,0 jours avec un taux de gémellité de 75 p. 100. L'indice de l'état général mesuré avec une échelle de points est passé de 2,4±0,2 à 2,8±0,2 pendant les 80 premiers jours de la gestation et s'est maintenu à 2,8 jusqu'au 45e jour avant la mise bas. De cette date à la mise bas, l'indice corporel est tombé à 2,2±0,2. Les concentrations plasmatiques en progestérone ont augmenté au cours de la gestation de fa?on significative, passant de 3,91±0,51 ng/ml au quarantième jour à 5,96±0,51 ng/ml au soixantième jour (P<0,05). Elles sont restées élevées jusqu'au cinquième jour avant la mise bas. Trois chèvres pseudogestantes avaient des profils de progestéronémie identiques à ceux des gestantes au cours des 80 premiers jours, mais l'élévation aux environs des jours 35 à 40 n'était pas significative et les concentrations sont retombées progressivement aux niveaux de base après le 100e jour. Les mêmes huit femelles, ainsi que quatre autres qui avaient été introduits en plus 60 à 70 jours avant la mise bas, ont été utilisées pour étudier le début de l'activité ovariennepost partum. Le taux de gémellité était de 83 p. 100. L'indice moyen de la condition corporelle au moment de la parturition était de 2,2±0,1. Au 35e jourpost partum cet indice moyen était tombé à 1,9±0,1 et les poids moyens étaient passés de 36,9±1,9 kg à la mise bas à 32,1±2,0 kg. La cyclicité ovarienne avait repris juste avant la reprise des indices moyens et des poids. L'intervalle moyen depuis la mise bas jusqu'au début de l'oestrus était de 97,3±9,5 jours, ce qui co?ncidait avec le temps moyen du sevrage soit 99,5±5,5 jours. L'auteur suggère que la tétée et la condition physique agissent comme des régulateurs de l'anoestrus post partum pour cette espèce. La saison peut également jouer un r?le régulateur, étant donné que les chèvres qui ont mis bas entre avril et juin (n=6) étaient en anoestrus pendant 82,7±15,0 jours, donnée à comparer à 112±7,3 jours pour celles qui ont mis bas d'octobre à février (n=6), quoique la différence ne f?t pas significative.

     

Ultrastructural features of the uterus in the sexually immature ostrich (Struthio camelus) during periods of ovarian inactivity and activity

The ultrastructure of the surface epithelium and tubular glands of the uterus in the immature ostrich is described. In ostriches with inactive ovaries the uterus is lined by a non-ciliated simple columnar epithelium, with basally located heterochromatic nuclei. Scanning electron microscopy revealed that these non-ciliated cells have a dense microvillous cover. A simple columnar to pseudostratified columnar epithelium, comprised of non-ciliated and ciliated cells, lines the uterus in birds with active ovaries. The ciliated cells possess a wide luminal region, which contains a nucleus and various organelles. An accumulation of secretory granules was observed in the apical regions of the non-ciliated cells, as well as in a few ciliated cells. In addition to non-ciliated and ciliated cells, a cell type with rarefied cytoplasm was also identified. These cells appear to correspond to calcium secreting cells identified in other avian species. The results of this study indicate that, although uterine differentiation is present in immature ostriches with active ovaries, the production of secretory product appears to occur mainly in non-ciliated epithelial cells.     

Effect of short-term hypothermia on lipid peroxidation and antioxidant enzyme activity in rats

This experiment was carried out to determine the effect of short-term hypothermia on blood malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glucose-6-phosphate dehydrogenase (G-6-PD) concentrations in rats. Twenty Sprague-Dawley rats were used weighing 180-200 g and on average 3.5 months old. They were randomly divided into two experimental groups: control (without cooling) and hypothermic (with cooling). The rats of the hypothermic group were cooled by immersion into cold water (10-12 degrees C), and the control rats were immersed into water of body temperature (37 degrees C) up to the neck without using any anaesthetic or tranquilizer for 3 min Rectal body temperatures of both groups were measured and blood samples to analyse MDA, GSH, SOD, GSH, GSH-Px and G-6-PD were collected immediately after the treatment. It was found that the MDA level was higher and the GSH and G-6-PD levels were lower in the hypothermic group than those in the controls. There was no difference between the control or hypothermic group regarding SOD or GSH-Px levels. It is concluded that acute hypothermia increased the lipid peroxidation and decreased the GSH and G-6-PD levels in rats.     

Enzyme activity in bovine cervical mucus during spontaneous and induced estrus

The purpose of the present research was to compare the enzyme activity of alkaline phosphatase (ALP), lactate dehydrogenase (LDH), α-amylase, α-manosidase, β-N-acetyloglucosaminidase, β-glucuronidase, and β-galactosidase in the cervical mucus of cows during spontaneous and induced estrus. Friesian cows (n = 106) were assigned to 4 groups: 1) no treatment; 2) progesterone releasing intervaginal device (PRID) for 12 days plus pregnant mare serum gonadotrophin (PMSG) at the removal of the PRID; 3) PGF2α2 doses 11 days apart; and 4) PRID for 7 days plus PGF2α 1 dose, 24 hours before removal of the PRID. Fourteen cows were excluded from the trial because of an inadequate quantity of cervical mucus collected or a lost PRID. The cows from the 3 induced estrus groups were artificially inseminated (AI) twice, while those with spontaneous estrus received only a single AI. Cervical mucus samples were collected from all cows 5 to 30 min before the first AI. The results are summarized as follows: 1) ALP and α-amylase activity for spontaneous estrus were similar to those for induced estrus; 2) LDH activity levels during spontaneous estrus were significantly lower (P < 0.001) than that in the P4 and P4+PGF2α induced estrus groups; and 3) glycosidases' activity was significantly lower (P < 0.001) in the spontaneous estrus group than that in the induced estrous groups. In conclusion, the activity of most enzymes in the cervical mucus of cows, in the present study, was significantly different between the spontaneous and the induced estrus groups.     

Acetylcholinesterase activity and lipid peroxidation in the brain and spinal cord of rats infected with Trypanosoma evansi

Neurological and locomotor clinical signs are described in animals infected with Trypanosoma evansi. These disturbances may be related to changes in the amount of acetylcholine (neurotransmitter) in the synaptic cleft. Therefore, changes in acetylcholinesterase (AChE) activity and lipid peroxidation in brain and spinal cord of T. evansi-infected rats were investigated. Each rat was intraperitoneally infected with 10(6) trypomastigotes kept in fresh (group A; n=13) and cryopreserved blood (group B; n=13). Thirteen served as uninfected (not-infected; group C). In days 4 and 30 post-infection (PI) the rats were anesthetized and subsequently decapitated to obtain the brain and the spinal cord (between vertebrae L1 and S2). The brain was removed and dissected (cerebellum, cerebral cortex, striatum and hippocampus) to measure the activity of AChE and lipid peroxidation, determined by TBARS levels. To verify if T. evansi was present in the central nervous system (CNS), brain structures of three rats of each group were processed by PCR T. evansi-specific. AChE activity was significantly increased in all brain structures and decrease in spinal cord in infected rats in 4 PI (P<0.05). The levels of TBARS were decreased in the brain structures, differently from spinal cord, which showed increased lipid peroxidation in 4 PI. The AChE activity in striatum, cerebral cortex, hippocampus and spinal cord reduced concomitantly with the increase of the enzyme in cerebellum of the infected rats (P<0.05), and the TBARS levels increased in cerebellum, striatum and spinal cord of infected rats compared to non-infected animals in 30 PI. The PCR was positive for T. evansi in all structures of the brain, confirming the presence of the parasite in the CNS. Based on the results, we conclude that the changes in AChE activity and lipid peroxidation in the CNS are induced by infection with T. evansi, suggesting that the parasite interferes with the cholinergic neurotransmission in this experimental condition.     

Nutritional anestrus in beef cows: body weight change, body condition, luteinizing hormone in serum and ovarian activity

Multiparous Hereford cows (n = 22) with moderate to good body condition scores (BCS) were randomly allotted to maintenance (M) or restricted (R) diets under drylot conditions. Cows on M diets received adequate feed to maintain initial BW, whereas R cows were fed to lose 1% of their initial BW weekly until luteal activity ceased. When most of the R cows became anestrous, their diet was increased to allow BW gain and resumption of ovarian cyclicity. Body weights and BCS were recorded weekly and luteal activity was assessed by weekly determination of progesterone in plasma. Concentrations of LH in serum were quantified in weekly samples and in samples obtained frequently at four selected times. Restricted cows had reduced BW (P less than .01) by 5 wk and reduced BCS (P less than .01) by 15 wk compared with M cows. Luteal activity ceased after 26 +/- 1 wk of reduced nutrient intake in 91% of the R cows; R cows had lost 24.0 +/- .9% of their initial BW and had a BCS of 3.5 +/- .3. Lack of luteal activity was associated with absence of behavioral estrus. Estrous cycles resumed 9 +/- 2 wk after the diet of R cows was increased, at which time R cows weighed 12 +/- 3% less than at the start of the experiment and had a BCS of 4.6 +/- .2. Concentrations of LH in serum samples obtained weekly were reduced (P less than .01) in R cows compared with M cows. In addition, LH pulse frequency was reduced (P less than .05) when R cows were initiating anestrus.(ABSTRACT TRUNCATED AT 250 WORDS)     

The correlation between serum selenium and blood selenium in cattle.

The selenium (Se) concentration of paired blood and serum samples from cattle was determined by 2 methods: 1) atomic absorption spectroscopy using hydride generation (HG-AAS), and 2) inductively coupled argon plasma emission spectroscopy using hydride generation (ICP). Samples from 327 cattle were analyzed by HG-AAS, and samples from 344 cattle were analyzed by ICP. The data were examined by linear regression analysis, and the technique of inverse prediction was utilized to determine prediction intervals for estimating blood Se concentration from known serum Se concentration. The correlation coefficients, by simple linear regression of serum Se on blood Se, were 0.79 (r2 = 0.62) and 0.88 (r2 = 0.77) for the HG-AAS data and the ICP data, respectively. For the HG-AAS data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. For the ICP data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. The prediction intervals were quite wide, and the accuracy of estimating blood Se from a known serum Se was not useful for diagnostic purposes. The use of serum Se concentration to assess nutritional status of cattle with respect to Se does not appear to be appropriate.     

Effect of timing and size of photoperiod change on plasma FSH concentration and the correlation between FSH and age at first egg in pullets.

1. ISA Brown pullets were transferred at 6, 9, 12, 15, 18 or 20.3 weeks of age from an 8 h photoperiod to an 8, 10, 13 or 16 h photoperiod. Plasma follicle stimulating hormone (FSH) concentration was measured at transfer at 7 and 14 d afterwards, and age at first egg (AFE) was recorded. 2. Plasma FSH concentration in pullets reared on constant 8 h photoperiods generally increased with age but with a trough at 12 weeks. Plasma FSH increased during the first 14 d of photostimulation to a significantly higher concentration, compared with constant 8 h controls, when the photoperiod was increased to 13 or 16 h at 9, 12 or 15 weeks; but for the increase from 8 h to 10 h photoperiods FSH was only significantly higher than controls when the change was made at 12 weeks. 3. The change in plasma FSH concentration 14 d after photostimulation was significantly correlated with mean AFE (reported in Lewis et al., 1997) and appears to be a better predictor of gonadal development than concurrent changes in plasma LH concentration previously reported (Lewis et al., 1994).     

Pattern of change in the concentration of milk acetone and its association with ovarian activity for pasture-based cows in early lactation

The variation in milk acetone concentration between cows and the resumption of ovarian activity was determined in 68 Holstein–Friesian cows grazing pasture. Cows calved in two groups approximately three weeks apart and were assessed over the first 60 d of lactation.

The largest coefficient of variation (152%) for milk acetone concentration between cows was found in the first week of lactation. This variability in milk acetone concentration was largely explained by a consistent cyclic pattern, in relation to the day of the study, with regular peaks at 21–26 d intervals. These peaks were synchronised between cows, and cows in the second group synchronised with cows in the first group.

Milk acetone peaks greater than 0.4 mmol/L were associated with a significant drop in milk yield, possibly due to energy deprivation around this time. In this respect, liveweight change over the first 60 d of lactation was significantly negatively correlated (r = − 0.29, p < 0.05) with the mean milk acetone concentration taken over the same period. However, there was no significant relationship (p > 0.05) between mean or maximal milk acetone concentration and the resumption of ovarian activity for the cows that resumed ovarian activity in the first 9-weeks post-partum.

The results of this study suggest that the use of milk acetone as a practical indicator of energy balance is limited due to its variability over time. Milk acetone concentration may be useful in experimental situations or when regular milk samples can be obtained in the field, such as in-line analysis. There is a need to undertake more research to elucidate the implications of the cyclic pattern of acetone concentration in milk on reproductive performance.     

Interrelationships between athyreotic and manganese-deficient states in rats.

Possible interrelationships of manganese-deficient and hypothyroid (thiouracil treatment) states in rats were examined. Clinical signs, necropsy changes, and plasma thyroxine concentrations were determined in control rats (group A), thiouracil-treated (hypothyroid) rats (group B), rats given manganese-deficient feed (group C), and rats given thiouracil and manganese-deficient feed (group D). Clinical signs observed included a hyperemic condition of the ears in group C and D rats that was considerably more severe in the latter group. One rat from group D also had middle ear changes, as reflected by a tilting of the head. Fluid intake was severely reduced in group D rats near the end of the 60-day experimental period and resulted in marked dehydration. Pathologic change (fatty liver) was observed at necropsy in only 1 rat from group D. Thiouracil treatment of rats reduced plasma thyroxine concentration to 48 to 68% of base line from experimental days 20 to 60. The same thiouracil treatment combined with feeding a manganese-deficient ration significantly reduced plasma thyroxine concentrations to 37% of base line at day 20 and 5% of base line at day 40; the concentration at day 60 was 76% of base line, apparently approaching normal because of concentration of the plasma (and thyroxine) in the dehydrated rats. Mean adrenal gland weight was significantly less than normal in group D rats, whereas mean thyroid gland weight in this group was increased, although less than that of group B rats treated with thiouracil only. Thus, clinical signs of deficiency were enhanced when athyreotic and manganese-deficient states were combined, and plasma thyroxine concentrations were markedly decreased, giving added meaning to the need for awareness of hormonal and trace mineral status of animals.     

Interrelationships between athyroetic and copper-deficient states in rats.

Possible interrelationships of copper-deficient (copper-deficient ration) and hypothyroid (thiouracil treatment) states in rats were examined. Clinical signs, necropsy changes, and thyroxine concentrations were determined in 6 groups of rats treated as follows: group A--nontreated control; group B--thiouracil treated; group C--fed copper-deficient ration; group D--thiouracil treated and fed copper-deficient ration; group E--thyroid-stimulating hormone (TSH) treated; and group F--TSH treated and fed copper-deficient ration. Clinical signs occurred first and were most severe in the thiouracil-treated rats fed copper-deficient ration and included conformational changes and slower maturation, weakening of ear cartilage, middle ear changes (reflected by tilting of heads), and alopecia. Fatty infiltration of hepatic tissue was found in all rats fed copper-deficient rations, and considerable fluid retention occurred in rats fed copper-deficient ration and subjected to daily TSH treatment. Adrenal gland weights were 81% of control values (adjusted for body weight) in thiouracil-treated rats fed copper-deficient ration, and hypophysis weights were 114 and 154% of control values in thiouracil-treated rats and thiouracil-treated rats fed copper-deficient ration, respectively. Thyroid gland weights were 281% of control values in both thiouracil-treated rats and thiouracil-treated rats fed copper-deficient ration. Plasma thyroxine concentrations were markedly reduced (9% of control value) in thiouracil-treated rats fed copper-deficient ration. Thus, copper-deficient and hypothyroid states were considerably enhanced when the 2 existed concurrently, giving added meaning and necessity to close surveillance of trace mineral concentrations and thyroid gland status.     

小鼠胚胎附植前后瘦素与脂肪细胞变化的相关性试验

1994年,Zhang Y等[1]首次克隆到肥胖基因(obese gene,Ob),并发现其编码产物为多功能分泌型蛋白质激素-瘦素(leptin).leptin由167个氨基酸构成,在分泌入血的过程中去除21个氨基酸组成的N端信号肽形成功能型瘦素.