Postnatal growth and development of the hairy-footed gerbil,Gerbillurus paebae exilis

The growth and development of six litters (21 pups) of captive Gerbillurus paeba exilis are described. Growth is slow with mean adult mass (32,4 g) being reached after 102 days, although the youngest sexually mature male and female were 63 days and 84 days old respectively. Physical development is also comparatively slow and weaning is completed after 30 days. Mass, tail length and hindfoot measurements were subject to much less error than head/body length data. Mass values of wild and captive gerbils are compared where possible. Two ‘critical periods’ in development were pin-pointed, i.e., (i) Day 12, when all the motor abilities developed rapidly, and (ii) Day 17, when the eyes opened and social behaviour followed. Behavioural development was divided into four periods: neonatal, transitional, socializing and juvenile.     

Behavioural Studies on Some Rhodesian Rodents

Field studies (Lake Kariba shoreline and Salisbury) and experiments with a captive colony of 12 species of Rhodesian rodents were undertaken for a period of three years. Comparative behavioural data are presented here with special reference to den and nest behaviour, group and territorial behaviour, reproductive and juvenile behaviour, and activity pattern. No species was found to be truly gregarious except Dendromus mesomelas, but Praomys (Mastomys) natalensis, Lemniscomys griselda, Tatera leucogaster, and Aethomys chrysophilus were found to tolerate crowded conditions in captivity. Nipple dragging of young was found in both species of Aethomys and in Acomys, with the remainder observed to utilise mouth carrying behaviour. It was noted that especially in Rhabdomys and Praomys (Mastomysj, and also in Lemniscomys, young have a strong tendency to scatter in all directions from a disturbed nest, even before their eyes open. The significance of nipple dragging, scattering and crowding behaviour and correlation to survival and tendency to irrupt are discussed. All species were found to be nocturnal (usually with irregular sub cycles of activity) except Rhabdomys (largely diurnal), Lemniscomys (diurnal/crepuscular) and Otomys (nocturnal/crepuscular).     

Observations on the post-natal development of the tiny musk shrew,Crocidura bicolor

Crocidura bicolor is the smallest of southern Africa's Crocidura shrews and little is known of its biology. A female, captured in the Kruger National Park, was observed giving birth to two young. The post-natal development of the young reported here was slower than the two previously published Incidences. Suggested reasons for the discrepancies are the differential diets of the mothers, their geographical origins and the smaller size of this female.     

Nest-building and activity patterns in four sympatric rodent species

Activity pattern and nest-building in four rodent species, Aethomys chrysophilus, Praomys natalensis, Otomys angoniensis and Lemniscomys griselda, collected from a single area, were studied in the laboratory. Activity: Praomys and Aethomys were active primarily during the dark phase of a 12L:12D light regime while Lemniscomys was active primarily during the light phase. Otomys was individually variable and could not be classified as either nocturnal or diurnal. Nest-building: Each species handled grass in a species-specific manner to the extent to which the leaves were cut into pieces and split lengthwise. These rodents can be placed in the sequence Praomys, Aethomys, Otomys, Lemniscomys with regard both to the extent of this cutting and splitting and to the completeness of the resulting nest with Lemniscomys using the smallest pieces to produce the best, often spherical, nest. It is suggested that these differences may be correlated with a combination of factors including body mass, time of activity, nest location and extent of sociality, which in turn are correlated with the species’ thermal requirements.     

Suckling behaviour in captive Dendrohyrax arboreus (Mammalia: Hyracoidea)

The suckling behaviour in four consecutive litters of a captive female Dendrohyrax arboreus is described. The young showed teat constancy which was established by day four of age without aggressive interactions, and maintained until weaning in all multiple litters. A preference for the more productive inguinal teats was apparent. Frequency of suckling bouts decreased with time but their duration increased. Most suckling occurred shortly after dawn and before dusk. The female showed decreasing maternal care in each successive litter.     

Water nipples or water bowls for weaned piglets: Effect on water intake,performance, and plasma osmolality

Abstract

Twelve litters were offered nipple drinkers (NIPPLE treatment) as the only source of water after weaning at 32–35 days of age, and 12 litters were offered water from a water bowl (BOWL treatment). Water usage was measured using water meters and blood samples were taken from four randomly selected piglets from each of eight. The water intake was similar in the two treatments for days 1–3 and days 4–7, but significantly higher in the NIPPLE treatment for days 8–14 (P<0.05). Daily gain was higher (P<0.05) in the NIPPLE treatment. The water quality was much better in the NIPPLE treatment, especially on days 7 and 9. Plasma osmolality was higher in the NIPPLE treatment at day 1, but at day 5 osmolality was highest in the BOWL treatment. We conclude that water supply from nipple drinkers is a better alternative for weaned piglets because of higher water intake, better water quality, and improved daily gain.     

Evaluation of the efficacy of oxfendazole against larval and adult Toxocara canis in unweaned dogs

The efficacy of oxfendazole given at a dose-rate of 10 mg kg^-1 for 3 consecutive days against adult and larval Toxocara canis was determined in four litters of naturally infected unweaned greyhound pups. Comparison of the worm-burdens of four pups treated on days 30–32 post partum with four matched litter-mate untreated controls gave an apparent efficacy value of 98-5 per cent, the numbers of adult T. canis at post mortem examination being 3 and 202, respectively. A similar comparison involving 10 pups treated on the 5th to 7th days of life, when the T. canis would have been in various stages of larval development, gave an overall efficacy value of 75.8 per cent, with worm-counts of 1,325 and 321 for control and treatment groups. However, a greater reduction (84.1–91.7 per cent) was observed in worms achieving a length of 40 mm by the time of post mortem examination (Day 21 post partum) than in shorter worms. In the latter case, no demonstrable anthelmintic activity was detected.     

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. II. Post-weaning diarrhoea

This study comprised 48,931 litters in 89 sow herds. During the study (1976-82) weaning age decreased from approx. 42 days to approx. 30 days. The mean incidence of post-weaning diarrhoea was 6.0% of litters weaned, with little variation by year but with considerable variation among herds. Within the individual herd increased incidence occurred over limited periods, probably associated with specific infections. Litters with diarrhoea during the suckling period had increased risk of post-weaning diarrhoea. The incidence of post-weaning diarrhoea increased with litter size at weaning. Thus, a litter of 11-12 piglets at weaning had 1.2 times higher risk than litters with 8-10 piglets. In contrast to pre-weaning diarrhoea, there was no association between parity of the sow and diarrhoea in the litter after weaning. Litters weaned below 2 weeks of age had a 2-fold risk of developing diarrhoea after weaning and a 2.4-fold higher mortality rate than did litters weaned at 6-7 weeks. Similarly, litters weaned at an individual piglet weight below 3 kg bodyweight had a 3-fold higher risk of developing diarrhoea after weaning and a 5-fold higher mortality rate than did pigs from litters weaned at a bodyweight of 7-8 kg. The incidence of post-weaning diarrhoea decreased with increasing herd size. Piglets from litters with post-weaning diarrhoea had reduced weight gains after weaning and were 2.3 days older at 25 kg bodyweight than piglets from non-diarrhoeic litters. Likewise, diarrhoea after weaning was associated with an increased incidence of diseases of the skin and respiratory tract. Thus the risk of contracting respiratory disease was 4 times greater in diarrhoeic litters.     

Ecological Observations on the Lorisoid Primates of African Lowland Forest

Desmodillus auricularis was kept in observation cages and subjected to an increased number of light-hours. The animal is nocturnal and its activity rhythm was adjusted using a red light to simulate darkness during the day. Three litters were produced from one pair and observations were made on twelve other litters born in the laboratory from pregnant field-trapped specimens. The breeding season appears to be all year. Litter size varied from one to five with a mean of 3,25. The gestation period was twenty-one days and gestation of a post-partum pregnancy was thirty-five days. The young were not attached to the nipple except when suckling. Behaviour is discussed with special reference to individual behaviour and parent-young relationship. Much of the general behaviour-pattern appears to be typical of most desert-adapted rodents. Hoarding and sandbathing were exhibited.     

Mammals of the Kammanassie Mountains,Southern Cape Province

The mammal fauna of the Kammanassie Mountain State Forest Reserve and Mountain Catchment Area was censused in the high-rainfall southeastern sector and low-rainfall northwestern sector from 2-12 February, 1979. Collecting yielded 287 specimens of 17 species of small mammals, while the presence of a further 16 species of larger mammals was confirmed. Mean trapping success was low (2,0%) which reflects the low density of most species. Of the 10 species of small mammals collected in the southeastern sector Acomys subspinosus and Otomys irroratus were abundant, while Rhabdomys pumilio, Praomys verreauxi and Myosorex varius were common; the other five species collected were rare. In the northwestern sector the species composition and relative density of each differed. Here Aethomys namaquensis was abundant, R. pumilio common, and five other species (including A. subspinosus and O. irroratus) rare. Few carnivores occur. Stomach samples of collected specimens yielded information on feeding habits; species vary considerably in their diet. Twenty-four species of both large and small mammals occur in the southeastern part, and 25 in the northwestern sector; 17 species are common to both.     

Anuran Ecology in Relation Particularly to Oviposition and Development out of Water

This paper is a contribution to the poorly known subject of wild rodent behaviour. Observations were conducted in the field and laboratory on the vlei rat, Otomys irroratus, as part of a comprehensive study of its ecology and life history.

Individual behaviour, social behaviour, and post natal development are described and discussed. It was found that the vlei rat is very shy and retiring in captivity. It can be considered as crepuscular, but activity tests conducted in the field and laboratory indicated some activity throughout the day and night.

Interactions of adults were tested and they were found to be very antisocial, with intrasexual aggression occurring when caged. Complex threat and communication patterns exist, a feature of asocial behaviour. Mating failed to occur in captivity, probably also a result of their antisocial nature.

Marking behaviour is very distinctive in this species and, combined with urination and possibly defecation, would appear to be useful in delimiting territories. It is concluded from their social habits, marking behaviour, and considerable overlap of home ranges that in nature their interactions with conspecifics are represented by a dominance hierarchy.

Several litters of young were reared. They are very precocial at birth and development proceeds rapidly. At birth the incisors are erupted, enabling them to cling firmly to the nipples of the mother. Most adult behaviour patterns are developed before weaning at 13 days.     

Fish-Induced Anemia in Rats

The described feeding experiment on rats comprised three groups, each consisting of 9 females. The control group was fed a commercial pellet diet fortified with brewer’s yeast and whole milk. Groups II and III were fed pasty fish diets which contained 90.5 % of undehydrated raw or boiled coalfish. The feeding experiment started when the rats were 34 days old. The rats were mated three times during the experiment.Undiversified feeding with a raw coalfish diet to rat females during gestation and lactation, and to their litters during weaning and after-weaning, resulted in evident anemic symptoms in the young animals. If boiled fish substituted the raw fish, the anemic symptoms were reduced, but not eliminated.Repeated gestation periods of mother animals, fed fish diets, did not result in increased anemic symptoms in their litters. Nor did the repeated gestation periods result in anemic mother animals.The anemic young rats, when continously fed the same fish diets, gradually improved their health state. The resulting adult animals were non-anemic and appeared normal as to growth and development.     

Canine Isosporosis – Epidemiology of Field and Experimental Infections

Isospora spp. are the causative agents of canine isosporosis. Of the 3590 diagnostic samples from Austrian dogs (≤2 years old), 8.7% contained Isospora oocysts, 78% of which from dogs up to 4 months of age. Non‐haemorrhagic and haemorrhagic diarrhoea were significantly more prevalent in Isospora‐infected animals than in coccidia‐negative ones. Twelve of 15 litters from a large commercial dog breeding unit (examined from the third to the 10th week of life) also excreted Isospora (average prevalence: 36.4%) in intensities from 333 to 35 000 oocysts per gram of faeces (opg). In experimental trials 26 3‐week‐old Beagle puppies were infected with low (600–6000), medium (10 000) or high (20 000) dose of Isospora ohioensis‐group or Isospora canis field isolates. Additionally 21 puppies were infected as above and treated with a symmetrical triazintrione. Parasitological and clinical parameters were examined. The two Isospora species differed significantly concerning intensity and duration of excretion. The pre‐patent period was 6–7 days for I. ohioensis and 10–12 days for I. canis. The latter species showed significantly longer excretion and higher opg. This was not influenced by simultaneous infections with both species. Individual patterns of faecal consistency were very variable, irrespective of the infection dose. Treatment significantly reduced both the intensity and the duration of oocysts excretion as well as diarrhoea in comparison with the infected, untreated group and thus proved to be effective against coccidiosis in experimental infections.     

DNA barcoding for identification of cryptic species in the field and existing museum collections: a case study of Aethomys and Micaelamys (Rodentia: Muridae)

DNA barcoding has been proposed as a method for species identification. However, this method has been criticised for its over-reliance on a single mitochondrial gene. In this study, four mitochondrial gene regions and one nuclear gene region were used to investigate their different abilities to identify tissue associated with museum specimens of Aethomys chrysophilus, Aethomys ineptus and Micaelamys namaquensis. Aethomys chrysophilus and the more recently elevated A. ineptus are indistinguishable on morphological grounds; however, their ranges are largely parapatric with only one syntopic locality currently known. All of the mitochondrial gene regions were able to separate M. namaquensis from A. chrysophilus and A. ineptus, but they varied in their abilities to resolve differences between A. chrysophilus and A. ineptus. The sequence results identified a specimen from KwaZulu-Natal that was misclassified and should have been identified as A. ineptus. Seven specimens that had not been reclassified following the elevation of A. ineptus to species level were identified as A. ineptus. Individuals of A. chrysophilus from Malawi could not be classified as either A. chrysophilus or A. ineptus, and may be a hybrid or a new, distinct species. This study indicates that DNA barcoding may be used to separate M. namaquensis from A. chrysophilus and A. ineptus, and although it was not able to separate A. chrysophilus and A. ineptus, it did indicate specimens from Malawi may be a new cryptic species.     

Toltrazuril and sulphonamide treatment against naturally Isospora suis infected suckling piglets: Is there an actual profit?

A study was carried out to assess the efficacy and the economic profit of prophylactic treatment against Isopsora suis with toltrazuril or with a sulfamethazine/trimethoprim combination in piglets from an intensive pig farm. Thirty-one litters were included in study. Eight litters were treated once with toltrazuril (20 mg/kg b.w.) at 3 days of age (Toltra group); 8 litters were treated with the sulphonamide combination (sodium sulfamethazine 35 mg and trimethoprim 7 mg/kg b.w.) for 3 consecutive days starting at 3 days of age (Sulfa group), and 15 litters were untreated (control group). Counts of oocyst per gram on pooled feces sampled from each litter were carried out on Days 7, 14, 21 and 28 and diarrhea was registered daily from pooled samples. Piglets were weighed on Days 1, 7 and 28 and mean weight gain (WG) and daily weight gain (DWG) were evaluated. The economic profit of treatment was evaluated comparing the WG of piglets of each treatment group from the day of birth to Day 28. On Days 14, 21 and 28, toltrazuril showed a better efficacy in controlling fecal oocyst output, diarrhea and weight gain compared with sulphamidic treatment (P < 0.001). The budgeting analysis showed a return of economic benefit of € 0.915 per toltrazuril-treated piglets and an additional cost of € 1.155 per sulphonamide-treated piglets.     

Breeding season and breeding potential of the greater cane rat (Thryonomys swinderianus) in captivity in South Africa

The cane rat, Thryonomys swinderianus, is an aseasonal breeder. It has a very low fecundity rate with an average litter size of 2.9 (range 1-5), producing a maximum of two litters per annum. The low annual fecundity is the direct result of the extended gestation period of the cane rat which exceeds 150 days in duration.     

Intermittent suckling: effects on piglet and sow performance before and after weaning

An experiment was conducted to study effects of intermittent suckling on creep feed intake and weight gain of litters. Loss of weight and backfat during lactation, as well as reproductive performance, were also measured. Batches of multiparous sows (Parity 1 to 12, 4.1 on average) were either suckled intermittently (IS, eight batches; n = 50) or continuously (control, eight batches; n = 62). Litters were weaned at 27 +/- 2 d of age, on average. Litter size (11.1 +/- 0.2 piglets, on average) was standardized within a batch within 3 d of birth. All litters had free access to creep feed and water from 1 wk of age onward. In the IS group, litters were separated from the sow for a period of 12 h/d (0930 to 2130), starting 11 d before weaning. Rectal ultrasonography was applied at d 3 after weaning to check the ovaries for follicle development or presence of corpora lutea. Creep feed intake by the litters during lactation was higher in IS litters than in control litters (686 +/- 57 vs. 314 +/- 42 g/piglet, P < 0.01). The distribution of creep feed intake shifted from a skewed one, with a majority of litters consuming less than 250 g/piglet in control litters, to a normal distribution, with an average creep feed intake of 500 to 750 g/piglet in IS litters. During the 7 d after weaning, creep feed intake in IS litters was also higher (281 +/- 15 vs. 204 +/- 9 g-piglet(-1) x d(-1), P < 0.01). The ADG of piglets during lactation was negatively affected by IS, resulting in lower weight at weaning (7,229 +/- 140 vs. 7,893 +/- 145 g/piglet, P < 0.05). During the 7 d after weaning, however, ADG was higher in IS litters (255 +/- 10 vs. 177 +/- 8 g-piglet-1 x d(-1), P < 0.01), and 7 d after weaning, the weights of the litters were similar (9,011 +/- 167 vs. 9,132 +/- 164 g/ piglet, P = 0.81). The IS litters that consumed little or no feed during lactation had an ADG after lactation that was higher than in control litters, with comparable creep feed intake during lactation: 204 vs. 136 g/d. Body weight loss by the sows during lactation was lower in IS sows (-10 +/- 2 vs. -16 +/- 1 kg, P < 0.05). A higher percentage of IS sows ovulated during lactation (22 vs. 3%, P < 0.01), and weaning-to-ovulation interval (excluding sows with lactational ovulation) was shorter in IS sows (4.7 +/- 0.2 vs. 5.3 +/- 0.2 d, P < 0.05). We conclude that IS increased creep feed intake during lactation, and that IS increased ADG after weaning, despite lower weaning weights. Ovulation during lactation was induced in 22% of the IS sows.     

The Duration of Farrowing in Relation to the Reproductive Performance of Yorkshire Sows

Records for 212 attended farrowings by 38 Yorkshire sows were examined. Eighty per cent of the farrowings were less than six hours, 18 per cent between six and 12 hours and two per cent between 12 and 17 hours duration. There appeared to be no marked relationship between the duration of farrowing and the size of litter.

In spite of a higher stillbirth rate in males, there were more male (52.3 per cent) than female piglets born alive. As the time taken to farrow increased from within 1-3 hours to more than eight hours, the percentage of stillborn piglets and the percentage of litters with stillbirths increased to 10.5 from 2.4 and to 61.1 from 18.2 per cent respectively.

Twenty-nine per cent of the litters were farrowed on the 114th day of gestation. As the gestation period lengthened to 117 days or more, from 113 days or less, there were corresponding increases in the duration of farrowing and the incidence of stillbirths, and a decrease in litter size.

A need to investigate the use of hormones to control parturition in sows was suggested.

     

Stereological analysis of Wistar rat testis during early post-natal development

Quantitative analysis of testis structure was performed during early post-natal development in Wistar rats. For this purpose, at 1, 7, 14, 21, 28, 35, 42, 60 and 90 days after birth, weights and volumes of testes were recorded and fixed in Bouin's solution. For stereological studies, 5-μm paraffin sections were stained with haematoxylin-eosin. Relative and then absolute volumes of seminiferous tubules, germinal epithelium, seminiferous tubuli lumina and interstitial tissue were estimated by point-counting method. The results showed that weight and volume of testis in rats increase 75- and 86.28-fold during post-natal development, respectively. The greatest growth rate (2.96-fold) of testis was observed between days 35 and 42. Also, diameter of seminiferous tubules increased significantly (P<0.001) between different ages and represented 5.55-fold increase during post-natal development. The percentage volume of tubular tissue increased 1.4-fold between birth and 90 days of age. Interstitial tissue formed 36.68±0.90% of testicular parenchyma at birth. This percentage decreased progressively during post-natal development until 90 (9.00±0.55%) days of age. Lumen of seminiferous tubules was recognized at day 28, and its relative volume increased with age. This study provides systematic data on the stereological characteristics of developing Wistar rat testis.     

Is Tryptophan ‘more’ Essential than Other Essential Aminoacids in Development? A Morphologic Study

An ontogenetic study was designed on developing rats in uterus of mothers tryptophan deprived at day 1 (exp. 1) and day 14.5 (exp. 2) of conception to verify the supposed determining role of the serotoninergic system (SS) in sexual differentiation in mammals. Tryptophan-free feeding was pursued uninterruptedly in the litter after birth, during lactation and post-natal development. Tryptophan-free pregnant rats were obtained by exclusion of tryptophan sources from chow. In both exp. 1 and exp. 2, the litter showed at birth a significant physical under evolution that worsened, during post-natal development, to a much more marked dwarfism in exp. 1 pups. Growth hormone concentrations in both sexes of dwarf rats were lower than that in the control rats. At 30 days post-natal age, whereas exp. 1 female rats showed a right-timed onset of puberty, no descensus of testes could be observed in male rats of same experiment. Dwarf male rats showed an evident hypotrophy of the whole reproductive apparatus. In histological examination of testes, neither spermatogenesis nor Leydig cells have been observed. Moreover, dwarf female rats showed a pronounced hypotrophy of reproductive organs, but a normal puberal status pattern was evident. In exp. 2, litters showed a less pronounced dwarfism, but a normal right-timed onset of puberty in both male and female rats. Data indicate that role of tryptophan in physical and sexual maturation in both male and female rats is essential.