Impacts of organic manganese supplementation on blood mineral,biochemical, and hematology in Afshari Ewes and their newborn lambs in the transition period

ObjectiveMaternal mineral status, including manganese (Mn), is critical for fetal growth as well as the health of the newborn lamb. Consequently, it is essential to supply minerals at sufficient levels for the pregnant animal to achieve the development of the embryo and fetus during gestation.MethodsThe current research was conducted to investigate the impact of organic Mn supplementation on blood biochemical, other mineral and, hematology in Afshari ewes and their newborn lambs in the transition period. Twenty-four ewes were randomly divided into three groups with eight replications. The control group was fed with a diet without organic Mn. The other groups were fed a diet supplemented with 40 (recommended by the NRC) and 80 (twice-recommended by the NRC) mg/kg of DM organic Mn.ResultsIn this study, the consumption of organic Mn caused a significant increase in ewes and lambs plasma Mn concentration. Moreover, in the groups mentioned, levels of glucose, insulin, and superoxide dismutase were significantly increased in both ewes and lambs. Concentrations of total protein and albumin were higher in ewes fed whit organic Mn. In both ewes and newborn lambs, the levels of red blood cells, hemoglobin, hematocrit, mean corpuscular hemoglobin, and mean corpuscular concentration in groups fed with organic Mn raised.ConclusionIn general, the nutrition of organic Mn, improved factors of blood biochemical and hematology in ewes and their newborn lambs, and since the twice-recommended NRC level did not cause poisoning, it was recommended to supplement the diet with 80 mg of organic Mn per kg of DM.     

Mob size of single-bearing or twin-bearing Merino ewes at lambing may not influence lamb survival when feed-on-offer is high

Limited research has suggested that higher lambing densities increase interference from foreign ewes at lambing which disrupts the ewe-lamb bond and compromises lamb survival. This may be particularly evident in mobs of twin-bearing ewes compared to single-bearing ewes because a greater number of lambs are born per day. Therefore, we hypothesised that; (i) decreasing the mob size of ewes at lambing has a greater impact on the survival of twin-born lambs than single-born lambs; (ii) the relationship between mob size and lamb survival can be explained by differences in the rate of interaction with foreign ewes and lambs at lambing; and (iii) ewes will utilise a limited area of the paddock at lambing and thus lambing density will be defined by the distribution of ewes in the paddock rather than the paddock area. Merino ewes were allocated into a 2×2 factorial combination of ewe pregnancy status (single- or twin-bearing) and mob size (high (n=130 ewes) or low (n=50 ewes)) on day 140 from the start of joining. Each treatment had two replicates excepting the low mob size for twins which had a third replicate. Ewes lambed at a stocking rate of 11 ewes/ha. Feed-on-offer during lambing exceeded 2400 kg dry matter (DM)/ha. Ewe-lamb behaviour was observed and dead lambs were autopsied over 11 days during the peak of lambing. The distribution of ewes in each paddock was recorded every 2 h during daylight hours by counting the number of ewes occupying 2500 m² grids. The proportion of ewes and their newborn progeny which interacted with foreign ewes at lambing did not differ between the high and low mob sizes for single- (24.9% v. 20.8%) or twin-bearing ewes (14.3% v. 19.6%; P=0.74). Similarly, interaction with foreign lambs did not differ between the high and low mob sizes for single- (14.5% v. 25.2%) and twin-bearing ewes (34.5% v. 26.4%; P=0.44). The distribution of ewes within the paddock did not differ between treatments (P=0.95). On average, single-bearing ewes which lambed at the high and low mob sizes occupied 34% and 36% of the paddock during daylight hours, and the corresponding values for twin-bearing ewes were 40% and 43%. Survival of twin-born lambs was lower than single-born lambs (75.3% v. 87.9%; P<0.01), however, lamb survival was not influenced by mob size regardless of birth type. These results suggest that higher mob sizes may not compromise lamb survival when feed-on-offer during lambing exceeds 2400 kg DM/ha.     

Spatial relationships between ewes and lambs

The spatial relationships between Merino ewes and their lambs was examined when lambs were 6–16 weeks old. In the first experiment, more than 50% of 6-week-old lambs were found in peer groups, with group size varying from 2 to 16 for the 31 lambs. Thereafter, both the percentage of lambs in peer groups and peer-group size declined progressively. The association in peer groups was strongest when the lambs were grazing. When they were lying, standing or walking they also associated together, but did so in close proximity to ewes.In a second experiment, spatial relationships of 15 ewes and their lambs were studied when the flock was grazing and the lambs were 12–16 weeks old. The strongest association, as measured by first and second nearest neighbours or by individuals within a 10-m radius, was between ewes and their offspring. However, some ewes and some lambs also showed significant preferences for the company of other individuals of their peer groups. Individual ewes and lambs differed in gregariousness, as measured by the numbers of sheep found within a 10-m radius of them.     

Genital stimulation facilitates maternal behavior in estrous ewes

Only a small proportion of ewes at estrus have been found to respond maternally to newborn lambs, and this low maternal responsiveness may be partially attributable to the absence of the genital stimulation which occurs at parturition. Therefore, the effect of artificial genital stimulation on maternal behavior of estrous ewes was investigated. Estrus was synchronized in 33 ewes by placement and withdrawal of progestin-saturated vaginal sponges. Estrous ewes were divided into two groups, a control group and a group receiving 5 min of artificial genital stimulation, and observed following presentation of newborn lambs. Significantly more stimulated ewes licked the lamb and emitted low-pitched bleats in a 30-min test. When genital stimulation was subsequently administered to control ewes, more of them also became maternal so that the two groups were no longer significantly different. These results indicate that absence of genital stimulation is one of the factors contributing to the low maternal responsiveness of estrous ewes. They also demonstrate for the first time that artificial genital stimulation is effective in eliciting maternal behavior in nonpregnant ewes even at physiological concentrations of estradiol.     

Incorporation of acetate into fatty acids and lecithin by lung slices from fetal and newborn lambs

Incorporation of acetate-1-(14)C into phospholipids and fatty acids by lung slices from fetal and newborn lambs and from ewes was studied in vitro. The distribution of radioactivity in the fatty acids of neutral lipids, phospholipids, and lecithin was determined. Acetate-1-(14)C was incorporated into myristic, palmitic, and C(18) fatty acids. Of the lecithin fatty acids, myristic and palmitic were the major radioactive fatty acids. The results indicate that the lung of fetal lambs is able to synthesize lecithin containing saturated fatty acids, a major constituent of pulmonary surfactant. A marked increase in the rate of acetate incorporation into lecithin was observed during maturation, and these rates were higher than those obtained in the ewes. A possible relationship between developmental changes in lecithin biosynthesis and pulmonary surfactant is discussed.     

Echinococcus granulosus in sheep: transfer from ewe to lamb of 'Arc 5' antibodies and oncosphere-killing activity, but not protection.

Fourteen ewes were orally dosed with 2000 E. granulosus eggs at 2 weeks of age, were mated at 19 months, and produced lambs when the cysts were 2 years old. One week after parturition, all 14 ewes had 'Arc 5' antibodies in their serum, as did 11/14 of their lambs. Fourteen uninfected ewes were immunized three times before parturition with E. granulosus eggs injected intramuscularly. Cysts grew at the first, or first and second site, but not the third, indicating that the ewes were immune prior to parturition. Most sera from these ewes and their lambs, and from 14 control ewes and their lambs, produced precipitin arcs with hydatid cyst fluid, but no 'Arc 5'. All lambs were challenged with 500 eggs 2 weeks after birth. At necropsy, cyst numbers within groups ranged from 3 to > 200, but there was no significant difference between the three groups of lambs. The immunized ewes did not pass a protection to their lambs that was effective when the lambs were challenged. 'Arc 5' antibodies were induced by prolonged infection with cysts, and were not seen in the sera of ewes immunized with eggs, although the eggs developed into cysts at the injection sites. 'Arc 5' antibodies did not protect lambs against infection, and were not correlated with protection in ewes. Subcutaneous injection of oncospheres into four ewes from each group at the time of lamb challenge showed that the immunized ewes were immune to this method of challenge, but the infected and control ewes were not.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ewe and lamb contact at lambing is influenced by both shelter type and birth number

A significant number of lambs born each year in Australia die within 72 h of birth. Periods of high wind, combined with rain and low temperatures can lead to marked increases in the mortality level. Under these climatic conditions mortality levels may be reduced with the provision of shelter. This study used contact loggers to compare interactions between ewes with twin lambs across two shelter types (Hessian and shrubs), while also comparing ewes with single and twin lambs in a single shelter type (Hessian). The contact loggers record the time of the initial contact (within approximately 4 to 5 m) between collared animals and the duration of each contact. Contact levels between ewes immediately after lambing were only 10% of the initial levels (1 h/day). For single-born lambs, lambs averaged 11 h contact per day with their mother, while for twinborn lambs, each lamb averaged 9.25 h/day with its mother and 14.7 h/day with its sibling. The level of contact between ewes and each of their offspring in the Hessian was 24% lower (P < 0.05) for ewes with twin lambs than with singles. For ewes with twin lambs the level of contact was 17% lower (P < 0.05) in the Hessian shelter compared with shrub shelter. We conclude that shelter type and birth number can affect the level of contact between ewes and their offspring.     

Iodine nutrition in ewes. 2. Effects of low to high iodine intake by ewes on the I content of biological fluids and plasma immunoglobulins G in newborn lambs

1. In two experiments samples of blood and organs were taken from newborn and young lambs born to five groups of ewes that received different dietary iodine (I) levels. Dietary I contents (mg/kg dry matter [DM]) in pregnancy and lactation, respectively, were: Experiment 1--0.36 and 0.26 for group C, 2.01 and 1.94 for group D; Experiment 2--0.13 and 0.12 for group A, 0.22 and 0.20 for group B, 10.77 and 8.88 for group E. 2. I intake of ewes had no effect on birthweight, body weight gain, or mortality between birth and wk 2 of life. No difference between the groups was recorded in the weights of brain, heart, lungs, and liver of lambs killed at birth. However, the weight of both the thyroid lobes in lambs from group E was lower than that of the other groups. The I content of the thyroid lobes of lambs from group A was 30-40% lower than that of the other groups. 3. The plasma inorganic iodine (PII) of lambs from birth to d42 of life was affected by ewe I intake, except for groups A and B, during the first 16 h of life. The PII of lambs increased with the I intake via milk in each group. The ratio of PII of lambs at birth/PII of ewes at d7 prepartum was 3.77, 2.96, 1.68, 1.39 and 8.62, respectively, for groups A, B, C, D and E. 4. The high I intake by group E ewes induced a higher plasma T4 concentration in lambs at birth. The decrease in plasma immunoglobulins G (IgG) recorded for the lambs in this group might be explained by this increase in plasma concentration.     

The effect of experience on twin-care in New Zealand Romney sheep

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.     

Distance recognition in ewes and lambs kept permanently indoors or at pasture

We tested the ability of Merino and Merino × Romanov ewes and lambs to recognise each other at a distance when given the choice between an alien partner and their own. Two groups of animals were studied. In the first group, multiparous ewes and their lambs were housed permanently indoors at a stocking-rate of 1 ewe/2 m². In the second group, ewes and lambs were run permanently outside in a paddock at a stocking rate of 1 ewe/500 m². Of animals living outside, 87% of ewes recognised their own lamb (100% of multiparous dams versus 84% of primiparous ones, P = 0.02). This differed significantly from a random choice. By contrast, the proportion of correct choices by ewes living inside (all multiparous) was significantly lower (64%) and did not differ from a random choice at the 5% level. Lambs reared outside recognised their dam in 95% of cases, versus 72% in lambs reared indoors (P = 0.01). Both frequencies differed significantly from a choice at random. It is concluded that the environmental conditions in which ewes and lambs are maintained can influence their ability to select their partners at a distance with the help of auditory and visual cues.     

Sister-chromatid exchange (SCE) analysis in mothers exposed to DNA-damaging agents and their newborn infants

The incidence of SCE in the lymphocytes of mothers and their newborn infants was determined. A detailed antenatal history of parental habits such as smoking, alcohol consumption and possible exposure to DNA-damaging agents was documented. The results showed that the SCE rate in the newborn is significantly less than that of their mothers. Mothers who consumed alcohol, but not cigarette smokers, had a significantly increased SCE rate compared to control mothers. However, these maternal habits did not affect the SCE rate of their infants. Neonates with neural tube defects showed a significantly increased SCE rate compared to normal babies.     

Mother–young bonding in prolific D’man and Romanov sheep

The effect of prolificacy on mother–young mutual recognition is still largely unknown in sheep. The aim of the present study was to investigate the ability of prolific ewes to develop an exclusive bond with their neonate and to recognize each other from alien subjects. Observations were performed on 11 D’man and 16 Romanov ewes with, respectively, 19 and 37 of their lambs. Maternal selectivity was tested at 24 h postpartum during two consecutive periods of 3 min. All mothers accepted their own lambs at suckling, while 21 out of 27 (78%) rejected the alien, thus displaying mostly selective nursing. To assess mother–young recognition, a two-choice test was performed at 36 h postpartum. Ewes clearly preferred their own lambs to an alien lamb and behavioral differences were not found between mothers of small (singletons and twins) and large litters (triplets and quadruplets). Romanov ewes reached their own lambsmore rapidly and spent more time near them than D’man ewes. Lambs from small litters, in particular light lambs, clearly preferred their mothers to an alien dam; however, both light and heavy lambs in large litters did not discriminate between the two stimulus ewes. D’man lambs clearly preferred their mothers to an alien dam; in contrast, such a preference was not as clearly demonstrated in Romanov lambs.     

The effect of prenatal photoperiodic history on the postnatal endocrine status of female lambs

Postnatal photoperiodic experience plays a pivotal role in determining the timing of ovarian activity in female lambs. This study examines whether a photoperiodic history gained while in utero is able to influence this timing.Pregnant Soay ewes were maintained in either long days (n = 7, 18 h light : 6 h dark; group PLD) or short days (n = 12, y h light : 18 h dark; group PSD) from 25 days of gestation. At birth, female lambs (n = 8 per group) were transferred to long days for 10 weeks, and then placed under short days until the end of the experiment at 38 weeks of age. Blood samples were collected from lambs on the day of birth and three times weekly for the duration of the study and the resulting plasma assayed for progesterone and prolactin.Although both gestational photoperiods produced, at best, abbreviated periods of ovarian activity, lambs born to ewes which experienced long days during gestation (group PLD) exhibited elevated plasma progesterone concentrations significantly earlier (P < 0.05) than lambs born to ewes exposed to short days during gestation (group PSD) (mean ± SEM, 193 ± 17 versus 244 ± 14 days for PLD and PSD groups, respectively. Plasma prolactin concentrations in newborn lambs born between late December and early April were not affected by the ambient photoperiod, but reflected the artificial daylength experienced by their mothers during gestation. Lambs born to ewes maintained under long days during gestation (group PLD) had significantly higher prolactin concentrations on the day of birth than lambs born to ewes maintained under short days during gestation (group PSD) (45 ± 5.4 ng/ml versus 7 ± 3.7 ng/ml respectively, P < 0.001). The mean birth weight, rate of live weight gain and live body weight of lambs at the end of the experiment did not vary significantly between treatment groups. These results suggest that the ovine foetus is sensitive to photoperiodic information prior to birth, and develops a photoperiodic history which, under the present experimental conditions, modulates the subsequent endocrine status of the neonatal lamb.     

Behavior of parturient ewes in group-lambing pens with and without cubicles

Maternal behavior was examined in 301 multiparous ewes (2–6 years of age) that were of predominantly Suffolk or Targhee breeding. The ewes gave birth in either a normal lambing pen (control) or in a similar pen modified by the addition of 8 cubicles (cubicles). Approximately 100 ewes were present in each pen at a time, creating a density of 1 ewe m^?2.Within the cubicle treatment, comparisons were made between the ewes which gave birth inside a cubicle (CUB-I, n = 64) and those that gave birth outside the cubicles (CUB-O, n = 92). CUB-I ewes spent less time moving about (P<0.01), travelled less distance (P<0.001), investigated fewer potential birth-sites (P<0.001) and spent more time in the cubicles (P<0.001) during the 60 min prior to giving birth than did CUB-O ewes. After giving birth, CUB-I ewes remained close to their lambs, which always remained in the cubicles. This resulted in CUB-I ewes and their lambs remaining closer to each other and to the birth-site than CUB-O ewes and lambs (P<0.001). CUB-I ewes were rarely interfered with by other ewes (17 vs. 82% interference for CUB-I and CUB-O ewes, respectively) and had fewer (0) lambs separated or stolen from them than did CUB-O ewes (13 of 144 lambs).In comparing the cubicle system and the control pen, it was found that interference with ewes and lambs was less in the cubicle treatment (P<0.01). In the cubicle system, there tended to be fewer lambs separated from their dams (5.4 vs. 9.6%) and less stealing of lambs (3.1 vs. 5.2%) compared to the control pen. It is concluded that the use of cubicles under these conditions reduces the incidence of poor maternal behavior in ewes.     

The effects of pasture availability for twin- and triplet-bearing ewes in mid and late pregnancy on ewe and lamb behaviour 12 to 24 h after birth

This experiment was conducted to evaluate the effect of offering ewes two different feeding levels, during mid and late pregnancy, on ewe and lamb behaviour 12 to 24 h after birth. Romney ewes, bearing twin (n = 80) or triplet foetuses (n = 56), were allocated to a pasture sward height of 2 or 4 cm between 70 and 107 days of pregnancy. In late pregnancy (day 107 to 147), half of the ewes were reallocated the alternate sward height, which produced four treatments: 2-2, 2-4, 4-2 and 4-4. Ewes were weighed on days 65, 92, 107 and 130 of pregnancy and lamb live weights were recorded 12 to 24 h after birth. Twelve to 24 h after birth the maternal behaviour score (MBS) of the ewes were determined, whilst their lambs were tagged. After the lambs were released, the behaviour of each ewe and her lambs was observed for 5 min. Ewe treatment and litter size had no effect on ewe MBS. However, as MBS increased (ewes stayed closer to lambs during tagging), ewes bleated less in a high-pitch and were quicker to make contact with their lamb. During the observation period, ewes in the 4-4 treatment had a greater percentage of their bleats in a low pitch (P < 0.05) than ewes in the 2-2 and 4-2 treatment (61.3% v. 41.3% and 38.8% low bleats, respectively) and more lambs born to 4-4 ewes (95%) bleated than lambs born to 2-2 ewes (84%; P < 0.05). However, lambs born to ewes in the 2-2 treatment bleated earlier than lambs in all other treatments (P < 0.05). Lambs born to 4-4 ewes were less likely (P < 0.05) to move towards their dam in order to make contact than lambs born to 2-2 or 4-2 ewes (3.1% v. 16.9% and 16.7%, respectively). These findings suggest that under the conditions of the present study, ewe nutrition had little effect on maternal behaviour. However, lambs born to ewes offered 2 cm pasture sward heights during mid and/or late pregnancy (2-2, 2-4 and 4-2 treatments) displayed behaviour that demonstrated greater 'need' whereas lambs born to ewes offered 4 cm during mid and late pregnancy sought less attention from their dam.     

Plasma and urinary clearance rates of atrial natriuretic factor during ontogeny in sheep

The present study was designed to determine the plasma clearance rate of atrial natriuretic factor (ANF) during development in chronically-instrumented fetal, newborn and adult non-pregnant sheep. To determine the contribution of the kidney in the metabolism of ANF, urinary clearance of ANF was also measured. Intravenous infusion of ANF (0.025 and 0.1 microgram.min-1.kg-1) produced a significant decrease in mean arterial blood pressure in newborn lambs and in adult non-pregnant sheep. Estimated plasma ANF clearance rate for the 0.025 and 0.1 microgram.min-1.kg-1 ANF infusion rate were respectively 177 +/- 55 and 155 +/- 34 ml.min-1.kg-1 in fetuses, 138 +/- 26 and 97 +/- 13 ml.min-1.kg-1 in newborn lambs and, 148 +/- 33 and 103 +/- 25 ml.min-1.kg-1 in adult nonpregnant ewes. Fetal, newborn and adult ANF plasma clearance rates during high ANF infusion rate (0.1 microgram.min-1.kg-1) were not significantly different. Low or high ANF infusion rate was not associated with significant changes in urinary ANF concentration or urinary ANF excretion rate. Taken together, the present study demonstrates that ANF plasma clearance rate is similar in fetal, newborn and adult non-pregnant sheep and that the excretory function of the kidney contributes only minimally to ANF plasma clearance rate.     

Reciprocal Allogrooming in Wild Impala Lambs

Adult impala engage in a form of reciprocal allogrooming distinguished by a high degree of reciprocity and ***lack of influence of dominance or relatedness on partner preference or distribution of grooming between partners. A previous study on reciprocal allogrooming of captive newborn impala lambs in a zoological park found that the allogrooming emerged as early as the first week after birth and was identical in structure and reciprocity to allogrooming in adults. Because these findings of apparently unique allogrooming behavior of newborn impala could have been a reflection of the effects of being born and raised in a small, stable captive herd, it was necessary to investigate reciprocal allogrooming in newborn impala in the wild. The emergence, reciprocity, rate, and partner distribution of reciprocal allogrooming in wild newborn impala were observed at two study sites: a national park in Zimbabwe and a game farm in South Africa. Maternal one-way grooming between mother and newborn emerged as distinct from reciprocal allogrooming and rapidly declined after week 1 postpartum. Reciprocal allogrooming by lambs was first seen between 5 and 8 d postpartum, and as soon as the behavior occurred it was the same basic pattern as seen in adult impala. The reciprocity index for lambs was near 0.5, indicating that lambs delivered as much grooming during an encounter as the partner. Lambs were grooming frequently with non-mother adults and other lambs by week 1 or 2; by week 3 and onward the allogrooming rate of lambs was more than twice that of their mothers, as predicted by the body size principle of the programmed grooming model. The strong predisposition of neonatal impala lambs to deliver reciprocal allogrooming as early as the first or second week postpartum would appear to reflect a genetically acquired adaptation to the threat of tick infestation in their natural habitat.     

Effects of retention of fetal membranes on subsequent reproductive performance of dairy ewes

Seventy-one pairs of ewes with or without retention of fetal membranes in the previous lambing season, were included in a cohort study of 25 flocks in southern Greece; in 27 pairs regulation of the breeding cycle was applied, whilst in the other 44 pairs natural mating took place. The following measures of reproductive performance were calculated: cycling rate, mating rate, return-to-estrus rate, abortion rate, lambing rate, total lambs born per ewe, liveborn lambs per ewe, stillbirth rate, lamb-bodyweight per ewe; furthermore, the incidence risk of retention of fetal membranes during the lambing examined in this study was also calculated. No statistically significant differences were observed in the reproductive performance among ewes that had or had not retained their fetal membranes during the previous lambing, whether the breeding cycle was regulated or not. The incidence risk of retention of fetal membranes among ewes that had not retained its placenta in the previous lambing was 1.6%, whilst that among ewes that had retained its placenta in the previous lactation was 0%. It is concluded that retention of fetal membranes did not appear to adversely affect subsequent reproductive performance of ewes.     

Role of the vomeronasal organ in neonatal offspring recognition in sheep

Twenty-five pregnant Dorsett ewes were randomly divided into three groups to test if ewes use their vomeronasal organs for offspring recognition during nursing. One group of eight ewes (procaine) were made anosmic by irrigation of the nasal olfactory apparatus with a zinc sulphate procaine solution. The second group of nine ewes (cauterized) had their vomeronasal organs rendered nonfunctional by cauterization of the nasoincisive duct. The third group of eight ewes were the controls. Parturition was synchronized in all ewes with betamethasone on Day 145 of gestation. Maternal responsiveness was tested two separate times with 1- to 2-day-old alien lambs. Each alien lamb trial was conducted 24 h apart. Cauterized ewes allowed alien lambs to suckle and they were unable to distinguish alien lambs from their own lambs, whereas the ewes in both groups with functional vomeronasal organs (procaine and control) violently rejected any alien lamb's attempt to suckle. Thus, female sheep use their vomeronasal organs for neonatal offspring recognition.     

Rank Acquisition Through Birth Order in Mouflon Sheep (Ovis gmelini) Ewes

The relationship between mothers' and daughters' dominance ranks was studied in a captive herd of mouflon sheep ( Ovis gmelini ), including nine adult ewes and their daughters, observed as lambs and yearlings. We found a positive correlation between the ranks of mothers and those of their yearling daughters, even though every mother dominated all the yearlings. We then tested the hypothesis that daughters from subordinate ewes became subordinate within their own age class because, as lambs, they had received more aggression from the other ewes in the herd. Recorded data were inconsistent with the hypothesis, even showing a trend for female lambs to receive aggression more frequently when born from dominant ewes. We also tested the hypothesis that resemblance between mothers' and daughters' ranks was due to inheritance of aggressiveness. No significant correlation was found between mothers' and daughters' aggressiveness, so the hypothesis was not supported. Finally, we found a significant concordance between mothers' ranks, daughters' ranks, and daughters' birth dates. Earlier-born daughters became dominant over later-born ones, probably because of larger body size and more advanced social behaviour. The age of most of the mothers was undetermined, but in mouflon sheep, older ewes generally dominate younger ewes and are known to lamb earlier during the birth season. Accordingly, it is suggested that dominant ewes have daughters dominant in their own age class, because (1) age influences the parturition date during the birth season, and (2) age strongly influences rank, even in individuals born during the same lambing season.