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1.
At lambing, ewes (Ovis aries) tend to isolate themselves from the flock and this is believed to be beneficial to the early relationship with their young. Later, they return to the flock and lambs progressively interact with other conspecifics. This study focused on the importance of isolation and socio-spatial factors on maternal recognition in lambs. All the ewes gave birth in individual 2 m2 pens and lambs were able to interact freely with their mothers. A first experiment investigated the role of isolation: INT1 lambs could progressively interact with other mothers and young in a pen which was increased in surface area from birth to 24 h (0–6 h: 1 ewe, 1 litter, 2 m2; 6–12 h: 2 ewes, 2 litters, 4 m2; 12–24 h: 4 ewes, 4 litters, 8 m2); ISO lambs remained in small pens (2 m2) and only with their mothers for 24 h. The lambs were submitted to a 5 min choice test between their own mothers and an alien ewe. At 12 h INT1 lambs, unlike ISO lambs, showed a clear preference for their mothers. ISO lambs still did not show any maternal preference at 24 h. The second experiment investigated the relative importance of social interactions while keeping the same space allowance for the two groups: INT2 lambs as described for INT1 in Experiment 1, and SPA lambs that remained isolated from the flock with their mothers but had the same increase in pen surface area as INT2 lambs. Both INT2 and SPA lambs displayed a preference for their own mothers at 12 h but INT2 lambs did so more rapidly. Our data also suggest that INT1 and INT2 lambs chose their own mothers at a distance. These results demonstrate that progressively increasing social interactions with flock members other than the mother facilitates the establishment of a preference for the mother in lambs. Increasing space allowance only also seems to have facilitating effects. This suggests that a rich socio-spatial environment from birth has beneficial effects on the development of filial bonding.  相似文献   

2.
The effect of cervical vagus nerve stimulation, gastric distension and CCK-8S administration was studied on the activity of 120 neurons located in the nucleus tractus solitarius (NTS) of anesthetized newborn lambs. One hundred cells responded to the three different inputs.The distribution of the cells in the NTS was from 3 mm rostral to 3 mm caudal to the obex, the major responsive cells being located at the level of the obex. Neurons were either excited or inhibited by gastric distension and CCK-8S, and the responses to these two stimuli were always in the same direction. A small number of cells responded to gastric distension and CCK-8S but not to vagus nerve stimulation.Injection of the CCK-A receptor antagonist 2-NAP abolished both the responses to CCK-8S and to gastric distension. The results are consistent with the idea that CCK-8S acts directly on vagal mechanoreceptive endings in the gastric corpus close to duodenum.These results from lambs may reflect the pathway by which gastric distension and peripheral CCK-8S modulate NTS cells activity during colostrum ingestion, which could in turn activate structures related to learning and memory processes involved in the development of mother preference.  相似文献   

3.
We investigated whether kids were able to discriminate their own mother from an alien one in a two-choice test on the day of birth when they had access to acoustic, visual and olfactory cues from their mother, and whether this discrimination depended on the selective maternal behaviour of the mother (i.e. exclusive nursing of own kids). When given the choice between their own mother and an alien equivalent dam, 8-h-old kids did not show a significant preference for their dam, whereas 12- and 24-h-old kids did. When given the choice between their own and an alien mother that were both non-selective because they had been rendered peripherally anosmic by irrigation of the nostrils with zinc sulphate, 12-h-old kids did not show a significant preference for their mother. These results are similar to those reported in sheep and may suggest that the contrast of behaviour between their own and an alien mother existing in normosmic does is important for discrimination of dams by kids at this age. Finally, testing 8-h-old kids in a smaller enclosure resulted in some improvement of their performance, although they still failed to display a significant preference for their mother. On the whole, kids are able to discriminate between their own and an alien mother goat as early as previously reported in lambs. The impairment of this ability when mothers are anosmic and not selective suggests that acceptance behaviours displayed by the mother may serve as one of the cues orientating the choice of the kid when given the choice between intact mothers. Finally, the present results do not suggest the existence of fundamental differences in the establishment of a preference for the mother between lambs, which are followers, and kids, which are hiders.  相似文献   

4.
Undernutrition restricted to the time around conception in sheep alters endocrine and metabolic responses in the offspring. Studies in rats suggest that such an early insult can also alter the behaviour of the offspring. We studied the effects of mild maternal periconceptional undernutrition (10–15% body weight reduction) on the lamb's response to separation from and reunion with the mother, and on the ewe–lamb bond, evaluated as the preference for each other over an alien ewe/lamb in a test enclosure, at 24 h, 1 and 4 weeks of age. Lamb birth weight was not affected by maternal nutrition. Maternal periconceptional undernutrition did not affect the lambs’ responses to separation and reunion (number of vocalisations, times to leave pen and achieve proximity with ewes) or the bond between ewes and lambs (percentage of time spent near their own dam/lamb). However, there were effects of sex, litter size and time on lambs’ responses to separation and reunion and on the ewe–lamb bond. Female lambs vocalised more during separation (P ≤ 0.01) and left the holding pen faster than males (P ≤ 0.05), and twins vocalised more than singletons (P ≤ 0.05). The time to leave the holding pen, achieve proximity with the ewes and number of vocalisations decreased with increasing postnatal age of the lamb (all P ≤ 0.001). Ewes showed a stronger preference for the lamb at 24 h and 1 week than at 4 weeks postpartum (P ≤ 0.001), whereas lambs followed an opposite trend, showing a lower preference for the mother at 24 h and 1 week and increased preference at 4 weeks of age (P ≤ 0.001). We conclude that periconceptional undernutrition does not affect offspring response to separation from the mother or the bond between ewes and lambs, but that these behaviours are affected by sex and litter size for up to 4 weeks after birth.  相似文献   

5.
We examined the respiratory effects of a patent ductus arteriosus in 29 premature lambs (131-135 days gestational age) after infiltrating the ductal wall with formaldehyde solution (Formalin) and placing a snare around the ductus to regulate its patency. The lambs were given sheep surfactant, paralyzed, and mechanically ventilated at birth. We first compared 8 lambs with open ductus and 13 lambs with closed ductus during the 12 h after birth. Although lambs with open ductus had greater pulmonary blood flow (301 +/- 36 vs. 188 +/- 11 ml.min-1.kg-1, mean +/- SE, at 12 h of age) and mean pulmonary arterial (44 +/- 3 vs. 33 +/- 2 mmHg) and left ventricular end-diastolic (6 +/- 0.6 vs 4 +/- 0.7 mmHg) pressures, we found no differences in dynamic respiratory compliance (Cdyn = 0.55 +/- 0.07 vs. 0.55 +/- 0.03 ml.cmH2O-1.kg-1), midtidal volume resistance (62 +/- 5 X 10(-3) vs. 62 +/- 7 X 10(-3) cmH2O.ml-1.s), or functional residual capacity (FRC = 27 +/- 3 vs. 26 +/- 2 ml.kg-1). Alveolar-arterial PO2 difference was lower in the lambs with open ductus (238 +/- 65 vs. 362 +/- 37 Torr). Next, we challenged eight lambs with two separate saline infusions (50 ml.kg-1 over 3 min), each given with the ductus alternately closed or open. When the ductus was closed, FRC was unchanged, but Cdyn increased by 18% immediately after the infusion. When the ductus was open, FRC decreased by 16% and Cdyn decreased by 12%. We conclude that the premature lamb is surprisingly resistant to changes in respiratory function from ductal patency during the immediate neonatal period.  相似文献   

6.
Behaviour of ewes at lambing was observed in a flock of N.Z. Romney sheep composed of selected (or “elite”) ewes that had produced litters of 2 or more lambs at least twice previously, and 2-year-old ewes that had produced 0, 1 or 2 lambs at 12 months of age. The observations concentrated on twin-bearing ewes.Only 6% of twin-bearing elite ewes became separated from a twin compared with 16% of primiparous ewes. Conflicts between elite and younger ewes over ownership of twin lambs were won by elite ewes in 6 of 7 cases, and elite ewes gathered their twin lambs together more quickly after artificial separation than primiparous ewes.Irrespective of litter size, primiparous ewes remained within 20 m of their birth-site for a mean of 11 h compared with 7 h for elite ewes, and the incidence of separation from a twin in primiparous ewes was higher with ewes that moved from the birth-site within 6 h of birth than in those that remained for more than 6 h. Also, primiparous ewes appeared more reluctant than elite ewes to leave one twin to recover the other that had been deliberately separated.The behaviour towards twins in the small number of 2-year-old ewes that had produced twins at 12 months of age was similar to that of the elite ewes in several respects, but contrasted with behaviour of primiparous mothers of the same age. This indicates that twin care improved with experience rather than age. The behaviour towards twins in 2-year-old ewes that had previously produced a single only tended to fall between that of primiparous ewes and ewes that had produced twins when 12 months old.  相似文献   

7.
ABSTRACT

In domestic sheep Ovis aries, the mother and the young display a preferential bond for each other that relies on multimodal inter-individual recognition. Lambs show a preference for their own dam shortly after birth, and this is important for their survival. The role of acoustic cues in this early preference for the mother is not clear. The aim of the present work was to analyze the timing of acoustic recognition of the mother and to identify the physical parameters used in the recognition of maternal bleats by the lamb.

In a first study, we investigated the ability of lambs to discriminate between the bleats of their own mother and an alien equivalent mother in a two-choice test. Both ewes were hidden behind a canvas sheet and lambs were not allowed to approach the dams closer than 1 m, thus preventing visual as well as olfactory perception. Tests were conducted 12 hr, 24 hr or 48 hr after birth (n=19 or 20/group). An indication of vocal discrimination was already present at 24 hr and at 48 hr lambs spent significantly more time near their mother than near the alien dam.

In a second step, we investigated which physical parameters of the bleats were important for recognition. For this, we conducted playback experiments with modified bleats at two weeks postpartum. Ours results show that lambs pay attention to a combination of various time, energy and frequency parameters: timbre (distribution of energy within the spectrum), amplitude and frequency modulations appear to be the most important parameters encoding the individual signature.

We conclude that vocal recognition between the ewe and her lamb plays an important role in the display of preferential mother-young bond from very early on. Our studies also demonstrate that the encoding of the individual signature is not limited to the frequency domain but rather involves a multiparametric encoding process.  相似文献   

8.
Familial correlations were studied in a sample of 618 sibships from a western neighborhood of Jerusalem, whose height (H) and weight (W) were measured longitudinally at the same age, from birth to 3 years of age. Covariate adjustments were applied to correct for change in mean of H and W with the sex of child and age of mother and for the effect of origin, education, and socioeconomic status of the mother, parity, and calendar year at birth. The highest sibling correlations were observed at birth or 1 month later (r = 0.45-0.46). Pooled sibling correlations were lower 6 months later (r = 0.33; r = 0.26 for H and W, respectively) and tended to increase again 12-18 months after birth. A clear trend of decline in sib-sib correlation for H and W measured 3 and 12 months after birth with increased spacing between siblings was observed. Our data provide evidence for transient environmental factors as possible sources of the observed temporal variation in sibling correlation for height and weight.  相似文献   

9.
Lung protein leaks in ventilated lambs: effects of gestational age   总被引:3,自引:0,他引:3  
To study the protein permeability properties of the ventilated premature lung, we delivered groups of eight lambs at 122 and 135 days gestational age and ventilated the lambs equivalently. The lambs at 122 days gestational age had been treated with natural sheep surfactant at birth, and both groups of lambs had similar pH and blood gas values to 3 h of age. Three groups of lambs at 146 days gestational age also were studied for comparison; four lambs were ventilated to normalized PCO2 values, four lambs were ventilated equivalently to the premature lambs with supplemental CO2 used to normalize PCO2 values, and four lambs were treated with natural surfactant and ventilated similarly to the preterm lambs. The percent recovery into an alveolar wash and lung tissue of 131I-albumin given by intravascular injection and of 125I-albumin given into the airways was measured in each animal after killing at 3 h of age. Full-term lambs had a small bidirectional leak of albumin to and from the alveoli and lung tissue. The recovery of intravascular 131I-albumin in the alveolar wash was 5.8- and 4.1-fold higher in lambs at 122 and 135 days gestational age, respectively, than in full-term lambs. The loss of 125I-albumin from the airways and alveoli also increased as gestational age decreased. The bidirectional flux of albumin to and from the alveoli increased as gestational age decreased in the prematurely delivered and ventilated lambs.  相似文献   

10.
Gonadotropins, prolactin (PRL), testosterone (T), delta 4-androstenedione, dehydroepiandrosterone sulfate and cortisol (F) levels were determined from 14 days before birth to term in 3 female and 3 male ovine fetuses with a chronically implanted venous catheter, and in the same animals from birth to 72 h of age. In both sexes, plasma gonadotropins and androgens were low throughout the period of study while plasma F increased with gestational age. After birth, plasma gonadotropins and PRL tended to increase progressively with time while PRL concentrations were significantly higher in female than in male lambs. F and T concentrations decreased significantly within the first 12 and 6 h of postnatal life. Higher T values were again observed at 36 h in male lambs. These data indicate that the fetal hypothalamic-pituitary-gonadal axis is relatively quiescent in the last 14 days of gestation but is activated within the first 72 h after birth.  相似文献   

11.
Twelve sets of twin lambs were delivered prematurely by cesarean section at 133-136 days gestational age and ventilated for 3 h with either high-frequency oscillation (HFO) or conventional mechanical ventilation (CMV). Blood gases and pH values were monitored at 30-min intervals, and ventilator settings were adjusted to maintain CO2 partial pressure (PCO2) values within the normal range. There were no differences in the sequential blood gas or pH values between the HFO or CMV lambs. Mean airway pressures (MAP) between 8.0 and 20.4 cmH2O were required, indicating lung disease of variable severity in the lambs. The bidirectional protein leak from the vascular space to the airways and alveoli and vice versa was measured with radiolabeled albumins given by intravascular injection and with fetal lung fluid at birth. The albumin leaks in both directions increased as MAP required to normalize PCO2 increased, but the degree of leak was independent of type of ventilation. Pathological findings of epithelial necrosis and hyaline membranes occurred to a similar extent in lung sections from both groups of lambs. In the HFO animals less phosphatidylcholine in the alveolar wash and more of a tracer dose of radiolabeled natural surfactant that had been given at birth became tissue associated. These results indicate a decrease in the initial secretion of surfactant and/or a stimulation of reuptake in the HFO animals. HFO did not protect the immature lung from the development of large protein leaks or the pathological changes of the respiratory distress syndrome.  相似文献   

12.
The aim of the present study was to estimate the onset of sexual maturity of F(2) lambs born to crossbred ewes (East-Friesian x Black-Head Pleven breeds) x East-Friesian rams based on measurments of plasma FSH, LH and 17beta-estradiol levels during postnatal development. The hormonal levels were measured by radioimmunoassay in blood samples taken from 107 ewe lambs at the age of 0 to 10 days, 1, 2, 3, 4, 5, 5.5, 6 months and at 1 year from anestrous ewes (birth - Day 0). Starting at a baseline concentration during Days 0-10, FSH rose to a peak at Month 2 and declined after Month 3 to levels equivalent to those seen in yearling, sexually mature ewes. Mean LH concentrations rose from baseline to the highest level in samples taken at 5.5 months and stabilized at 6 months to the level seen in yearling ewes. The preovulatory LH peak was recorded in 5.5 month-old lambs. Neither FSH nor LH declined to baseline concentrations in lambs after the initial 10 days of life. 17beta-estradiol fluctuated, showing an initial rise in samples taken between Days 0-10 and Month 2, followed by insignificant variations between different ages and were near to those in yearling ewes. The data suggest that the sexual maturity in lambs is attained at 5.5-6 months of age. The findings allow us to suggest that these crossbred ewes might be fertilized at an earlier age (11-12 months) if they had reached the neccessary body development (body weight: 75-80% of that of adult ewes). They also might be included earlier in estrous synchronization programs in order to give birth to 3 lambs in 2 years.  相似文献   

13.
Ovarian follicles during infancy in Romanov and Ile-de-France ewe lambs   总被引:1,自引:0,他引:1  
The ovaries of new born lambs (15 Ile-de-France and 19 Romanov, 34 ovaries) and of 4-week-old lambs (6 Ile-de-France and 12 Romanov, 18 ovaries) were examined histologically to compare ovarian follicular development in infant lambs of breeds differing in their prolificacy. Breed was the major factor affecting follicular population at birth. Ile-de-France lambs had a higher total number of growing follicles (P less than 0.001), and more preantral (P less than 0.001) and antral (P less than 0.005) follicles than did Romanov lambs. Furthermore, the size of the largest follicles was also reduced in Romanov compared to Ile-de-France lambs. At 4 weeks of age, most of the features of the ovarian follicular population except the mean size of the third largest follicle were similar between the two breeds. However, atresia of antral follicles had appeared only in Ile-de-France and not in Romanov lambs. When a challenge with exogenous gonadotrophins (1000 i.u. PMSG followed by 1500 i.u. hCG) was attempted, ovulation was triggered in 2/6 and 0/12 Ile-de-France and Romanov lambs respectively. Massive follicular development was noted in 3/6 Ile-de-France lambs but in none of 12 Romanov lambs. Retardation of follicular development together with retardation in the establishment of ovarian sensitivity to gonadotrophins are therefore features typical of the ovaries of Romanov lambs compared to Ile-de-France lambs during the post-natal period.  相似文献   

14.
Stimulation by naloxone, an opioid antagonist, of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion was examined in spring-born crossbred ram lambs raised under natural photoperiod. Vehicle (n = 6) or 1 mg naloxone/kg vehicle (n = 6) was injected (i.m.) 3 times at 2-h intervals at 5, 10 and 15 weeks of age and 4 times at 2-h intervals at 20, 25, 30 and 35 weeks of age. Blood samples were taken every 12 min for 6 h at 5, 10 and 15 weeks of age and for 8 h at 20, 25, 30 and 35 weeks of age. Naloxone had no effect on age at sexual maturity (controls 239 +/- 23 days; naloxone 232 +/- 33 days). The only significant (P less than 0.05) effect of naloxone on FSH was a greater pulse amplitude in 10-week-old treated lambs than in control lambs. Naloxone treatment resulted in greater LH pulse amplitude at 5 and 10 weeks of age (P less than 0.05), lower basal serum concentration of LH at 10 weeks of age (P less than 0.05), greater LH pulse frequency at 25 weeks of age (P less than 0.05), and greater mean serum concentrations of LH, basal LH and LH pulse amplitude at 35 weeks of age (P less than 0.01) than in the controls. In both groups of lambs, mean and basal FSH, and LH and FSH pulse amplitude were highest at 5 weeks of age and fell with age. LH pulse amplitude was lowest at 35 weeks of age (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

15.
The objectives of this study were to determine the effects of buserelin or saline treatment on ovarian function (Experiment 1), plasma PGFM concentrations and oxytocin stimulated prostaglandin F(2alpha) (PGF(2alpha)) release (Experiment 2) in ewe lambs and ewes. Welsh Halfbred ewes (n=26) and ewe lambs (n=24) were mated to vasectomised rams at synchronised oestrus and on Day 12 post-mating each animal was injected intramuscularly either normal saline or 4 microg buserelin. In Experiment 1, plasma progesterone and oestradiol concentrations were determined in samples collected by jugular venepuncture 1h before and at 0, 2, 4, 6, 8, 24, 48 and 72 h after treatment (n=7 per treatment group). Progesterone concentrations increased (P<0.05) from 2 to 8h after buserelin treatment and returned to basal levels after 72 h, whereas oestradiol concentrations were maximal at 2h post-treatment and returned to basal levels after 24h (P<0.05). Oestradiol concentrations were lower (P<0.05) in buserelin-treated animals than controls at 72 h post-treatment. Basal and post-treatment progesterone concentrations were greater (P<0.05) in ewes than in ewe lambs but oestradiol levels were similar for both age groups. Ovulation rate, determined by laparoscopy on Day 14, was similar for both age groups (ewes 1.1; ewe lambs 1.0). Buserelin treatment induced accessory corpora lutea in ewes (4/7; 57%) but not in ewe lambs (0/7; 0%). In the Experiment 2, plasma PGFM concentrations were determined in samples collected at 20-min intervals for 6h on Day 14 and at 20-min intervals for 1h before and at 10-min intervals for 1h and then at 20-min intervals for a further 3h period after an intravenous injection of oxytocin (1IU/kg body weight) on Day 15 post-oestrus. In this experiment there were five ewe lambs and six ewes per treatment group. There was no effect of buserelin treatment or age on basal PGFM concentrations on either Day 14 or 15. Although peak PGFM concentrations tended to be lower in buserelin-treated animals, the difference was not significant (P>0.05). However, peak duration following oxytocin challenge on Day 15 post-mating was shorter (P<0.05) in control ewes compared with control ewe lambs. In conclusion, buserelin treatment given on Day 12 post-oestrus enhances luteal function more in ewes than ewe lambs and after a transitory increase, reduces oestradiol concentrations in both ewes and ewe lambs. However, buserelin treatment does not significantly attenuate the luteolytic signal.  相似文献   

16.
A study was made on protein metabolism and hormonal changes following birth in newborn lambs fed amino acids alone or in combination with lactose. Eight newborn lambs taken from their mother immediately after birth were fed hourly for 8 h, either with a solution of peptides and free amino acids obtained by mild hydrolysis of whey proteins (4 lambs; diet AP) or with the same solution + lactose (4 lambs; diet APL). L-[4,5-3H] leucine was continuously perfused into a jugular vein for 6 h when the lambs were 2 h 30 min old. Plasma glucose and insulin levels increased after birth in APL lambs whereas they decreased in the AP; these differences were significantly different. Plasma cortisol levels remained unchanged throughout the experiment. Free essential amino acid levels did not vary when lambs were older than 4.5 h; they depended on the corresponding amino acid intakes. Plasma free threonine, valine, isoleucine, leucine, tyrosine and lysine were lower in APL than in AP lambs. The plasma leucine irreversible loss and leucine oxidation were higher in AP than in APL lambs. The plasma flux of leucine from whole body protein breakdown was lower in APL than in AP lambs inasmuch as the plasma flux of dietary leucine may be estimated by the amounts of leucine ingested in both cases. No significant difference was found for the fractional synthesis rates of tissue proteins such as liver, skin, skeletal muscle, lung, brain and whole body. These rates for skin, muscle and whole body were close to those previously measured in colostrum fed lambs. The increase in whole body protein accretion resulting from lactose feeding in combination with amino acids seemed to result from a decreased protein breakdown that could be mediated by the insulin response.  相似文献   

17.
《Small Ruminant Research》2009,85(1-3):35-40
The effects of follicular aspiration for oocyte retrieval on the attainment of puberty and growth rate were studied in winter-born (9 treated and 6 control) and autumn-born (5 treated and 5 control) ewe lambs. In the treated animals (i.e. in which follicular aspiration was performed after ovarian stimulation), laparoscopic oocyte pick-up (OPU) was performed at the age of 12–13, 16–17 and 20–21 weeks. From the 8th until the 57th week of age, serum progesterone concentration was determined in blood samples collected at weekly or bi-weekly intervals. Serum oestradiol concentration was measured in blood samples collected prior to each FSH administration at OPU, and 2 and 24 h thereafter. All lambs were weighed at birth, the 6th and 8th week of age and thereafter at monthly intervals until the 34th (winter-born) or 52nd (autumn-born) week of age. Radiographic images of the right antebrachium and completion of skeletal maturation (radius) were used to assess the growth rate. Serum oestradiol concentration increased in response to FSH administration, but decreased to normal basal values 24 h after OPU. Autumn-born ewe lambs attained puberty at a later stage, compared to the winter-born animals. In most OPU-treated winter-born lambs, the first luteal phase was of short duration. This was not observed in winter-born controls, nor in any of the autumn-born lambs. No differences were detected regarding the age at the onset of puberty between treated and control animals. From the 13th to the 26th week of age, winter-born treated lambs were lighter than the controls (27.3 ± 1.6 vs 34.3 ± 1.9 kg at 26 weeks of age, respectively). From the 16th to 34th week of age, radius length differed between the treated and control winter-born lambs, but not between autumn-born lambs. Ossification of the radial growth plate was not complete until the 34th (winter-born labs) or the 52nd (autumn-born lambs) week of age. It is postulated that repeated OPU can be safely applied to prepubertal lambs, with no consequences on the time to onset of puberty, whilst the growth rate of donor animals is also not affected.  相似文献   

18.
In two trials, lambs were trickle infected with 400 or 1000 infective larvae of Haemonchus contortus (HcL(3)), twice weekly for 4 weeks from the day of birth. Following anthelminthic treatment at 6 weeks (Trial 1) or 7 weeks of age (Trial 2), lambs were challenged 1 week later with a trickle infection totalling 5000 (Trial 1) or 10000 HcL(3) (Trial 2). In both cases, significant protection (P<0.05) ranging from 42 to 79% was achieved against egg and worm counts. Serum antibody responses as well as abomasal lymph node cell proliferation and production of interferon-gamma or interleukin (IL)-5 did not differ significantly between immunised and control lambs. The results are consistent with earlier findings that neonatal lambs can generate protective immunity against Trichostrongylus colubriformis, but the underlying mechanism(s) remain to be determined.  相似文献   

19.
The rate of reproductive development in juvenile male Siberian hamsters is strongly influenced by daylength (photoperiod). Recent studies indicate that reception of photoperiodic cues begins during fetal life. The present experiments yielded a further demonstration that developing male Siberian hamsters receive information about the photoperiod to which their mother is exposed during pregnancy. The possibility that photoperiodic information is transmitted from mother to young after birth was investigated by cross-fostering young gestated on 12L and 16L to mothers from the other photoperiod. Litters were cross-fostered on the day of birth and then were transferred, along with their foster mothers, to 14L. We found no influence of the mother after birth, indicating that transmission of photoperiodic information from mother to young must occur during gestation. To determine if the pineal gland of the mother is required for this response, adult females were pinealectomized or sham-operated and paired with intact males in 12L, 14L, or 16L. After parturition parents and offspring were exposed to 14L. The influence of prenatal photoperiod on postnatal testicular development in 14L was blocked by pinealectomy of the mother. Postnatal testicular development was retarded in offspring that experienced a photoperiod transfer from either 15L to 14L or 8L to 12L at birth. In contrast, the inhibitory effect of a transfer from 16L to 14L at birth was abolished when juvenile males were exposed to a single long photoperiod (16.3 h light) at age 17-21 days and then were returned to 14L.  相似文献   

20.
The present study was conducted to evaluate the effects of FecB genotypes on body weight, average daily gain (ADG), ewe's productivity efficiency (EPE) and litter size in FecB introgressed GarolexMalpura (GM) crossbred sheep. A total of 235 GM lambs were selected randomly and screened for FecB mutation using forced RFLP-PCR. The majority (69.8%) of GM individuals were carriers (BB and B+) for the FecB mutation and frequency of the FecB allele was about 0.40. The FecB genotypes were significantly (P<0.01) associated with the lamb's body weights from birth to 12 months of age. The generation wise (F(1), F(2) and F(3)), lamb's body weight did not differ significantly at birth, 6 and 12 months of the age, while it differed significantly (P<0.05) at 3 and 9 months of age. The ADG1 (0-3 months) was significantly associated (P<0.05), but not the ADG2 (3-6 months) and ADG3 (6-12 months) between genotypes. Type of birth and sex significantly (P<0.01) affected the body weight from birth to 12 months of age; and body weight of single born lambs was significantly higher (P<0.01) than that of twins and triplets from birth to 12 months of age. Type of birth significantly (P<0.01) affected the ADG1, but had no significant effect on ADG2 and ADG3. Year of birth did not affect the birth and weaning weights, but it significantly affected (P<0.01) the body weight and ADG's after weaning ages. The EPE was affected significantly (P<0.01) by the FecB genotypes at birth, 3 and 12 months of age. The EPE of B+ and BB ewes were 7.86 kg (36.9%) and 2.32 kg (10.9%) higher as compared to ++ ewes at 12 months of age, respectively. The mean litter size of BB ewes (2.17+/-0.24) was significantly higher (P<0.01) than that of B+ ewes (1.73+/-0.04) and ++ ewes (1.03+/-0.23). The present study indicated that the body weight and ADG of carrier lambs (BB and B+) was comparatively lower than that of non-carriers (++), while EPE of B+ ewes was comparatively higher than that of BB and ++ ewes. Further, it is interesting to note that heterozygous and homozygous state of individuals increased 0.70 and 1.14 extra lambs as compared to non-carriers (++), respectively.  相似文献   

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