Rat weaning age

Rodent Breeding and Weaning - Institutional Animal Care

  1. Therefore, the pups may be not ready for weaning at 21 days of age. Delaying weaning until 28 days of age may be an acceptable alternative. However, this must be approved in the IACUC protocol. If a strain requires delayed weaning, the male should be removed prior to parturition, (i.e. when the female is visibly pregnant at ~14 days gestation)
  2. Baby Rat Growth: Birth to Weaning - Rat Guide Read More. 1 / 1. Favorite See All. Gitterle-p1. gallery baby rat growth from rat guide baby rat growth photos. Powered by SmugMug Owner Log In.
  3. At approximately two weeks of age the pup's eyes are opening and it is beginning to eat bits of the mother's food. By three weeks the babies are eating anything they can get ahold of and playing wildly. At four weeks they are completely weaned. The developmental photos can show you what to expect as your babies grow

Baby Rat Growth: Birth to Weaning - Rat Guide - JoinRat

  1. Separating By Health, Safety, & Natural Weaning Male rats should be separated from female rats no later than 6 weeks old. While the risk of pregnancy is very low, the risk of pregnancy is dangerous for such a young female rat. In addition, the male kits could impregnate their mother
  2. Breeding Age of Rats; Weaning Mice. Breeding Age of Rats. Laurel Summerfield, Burke, VA Q I had my first litter of nine baby rats, but I was worried that mom was not taking care of them properly because she was so stressed about being totally confined after semi-freedom. Well, she settled down completely and they all survived
  3. Weaning Age at weaning: mice & rats: 21 days can be up to 28 d if approved in protocol, or clinical reason Genotyping: up to 5mm tail; or use ear punch/notch recommend tail snip <17 days > 17d use anesthetic Separate before puberty: avoid accidental pregnancies Avoid overcrowding: limit = 1 litter/cage weight limitations: Guid
  4. Mom is in the process of weaning them. 29 Days. 30 Days. 31 Days. 32 Days. 33 Days. 34 Days. 35 Days (5 weeks). They are continuing to grow very quickly and you will start to notice a size difference between males and females. 36 Days. 37 Days. 38 Days. 39 Days. 40 Days. 41 Days. 42 Days (6 weeks)
  5. Although female rats do not experience actual menopause, their reproductive ability can begin to subside anywhere between 9-12 months of age according to some studies 2, but it's typically more common for it to occur between 15 and 18 months of age
  6. Female rats produce up to 12 litters per year! Plus, these females can begin to bear children as early as when they're 5 weeks old. Amazingly, rats only need to gestate for 21-23 days before they're ready to birth 6-12 newborn baby rats. As they get older, breeding does slow down

Birth to Weaning - Rat Guid

  1. Weaning Should Be Done Firstly, it's important to note that rats only start to wean at around the age of 4 weeks old. That is until that age - a rat should never be separated from its mother except in an emergency situation because it needs its mother's milk to survive
  2. To evaluate the effects of weaning age on morphological changes that occur in the intestines of rats, we assessed intestinal histomorphometry and somatic growth in 21-days-old pups and 90-days-old mature rats that had been weaned early (day 16), normally (day 21), or late (day 26)
  3. 5.5.2. Generally, laboratory rats are weaned between 21 and 23 days of age. Most strains are weaned when they are 21 days old. 5.5.3. Weaning age may vary depending on weanling size and maturity, some strains benefit from being weaned later. When pups are to be weaned after 21 days of age, the female must be separated fro
  4. Periderm seals of ears and eyelids vanish; active feeding begins within next 3 days and weaning after 1 week (total weaning age, 45-48 days for rats and mice) Reference: Witschi E. Rat Development. In: Growth Including Reproduction and Morphological Development
  5. The usual litter size is 8 to 18 pups. Baby rats are born deaf and blind. The cage should be kept in a quiet place and the litter should not be disturbed for at least 7 days after birth, especially if this is the female's first litter. Weaning occurs about 21 days after birth
  6. imize adverse events associated with housing newly weaned animals. 307.2 Training Requirement

A. Age of Pups at Weaning Weaning age for rat pups is routinely 21 days of age. In the case of some inbred, genetically modified or mutant strains, it may be advantageous to allow the pups to remain with the female for 28 days Breeding trios (one male, two females) in a 100 sq. in. cage (standard rat cage). If post-partum estrus is used in standard mouse cages, the first litter must be weaned by 21 days of age to prevent the presence of two litters in a cage, i.e. no extended weaning is allowed if post-partum estrus is used Weaning age for rat pups is routinely 21 days of age. In the case of some inbred, genetically modified or mutant strains, it may be advantageous to allow the pups to remain with the female for 28 days. This must be approved in the protocol, or on a case-by-case basis by the facility veterinarian

A rat mot. At what age to properly wean and separate babies from their mom is always a topic with a ton of different opinions on! This is just alittle bit of info on when and more importantly why I do what I do. When to wean and why? First lets discuss what weaning means. In my opinion weaning should be done naturally whenever possible At age 90 days, and the next generation the litter size of early-weaned rats was bigger than those weaned on days 26 or 21. Conclusions: Early weaning significantly enhances the testes' size, vasculature, and seminiferous tubular walls, and enhances the liter size compared to late weaning Here you can see what your baby rats should look like as they age from birth to five weeks of age: Birth to Weaning - Rat Guide (Weeks One through Four) Baby Rat Development - AFRMA (10 hrs, 36 hours, 5 days, 11 days, 14 days, 2.5 weeks, 4 weeks, 6 weeks) Pictures of the Pinkies - Rattie World O' Comfort (Several photographs every day, Days 1-24

When Can Baby Rats be Weaned and Leave Their Mother for

According to the American Medical Association, the a verag e age of menopause in women is. 51 years (51 × 365 = 18615 days), [33] and female. rats enter menopause betw een the ages of 15 and. 20. i. Adult Rat: Any rat that is of weaning age or older and able to eat solid food and drink from the water source. ii. Rat Pup: Any neonatal or young rat up to 24 days of age. iii. Breeder Cage: Any cage that contains one male with one female, a female with a litter, or any cage where pups may reasonably expected to be born. iv In rats. Rats that are raised in a laboratory, or are bred for selling purposes, are usually weaned at the age of 3 weeks. If the pups were left with their mother then weaning would not occur until they were older. This can have some health and behavioral benefits in the rats One of the most important events in the early stage of life is weaning, and we recently reported that precocious weaning augments anxiety and aggressiveness in rats and mice. In the present study, we investigated the autonomic responses to stress in two groups of rats: the early-weaned group (weaned at 16 days of age), and the normally weaned.

Development of place navigation in rats from weaning to puberty. Schenk F. Young hooded rats were trained to escape onto a hidden platform after swimming in a pool of opaque water. Subjects 21, 28, 35, 42, and 64 days of age on the first training day were given 28 trials on 5 consecutive days The Laboratory Rat: Relating Its Age with Human's. Pallav Sengupta. ABSTRACT. By late 18. th. or early 19 century, albino rats became the most commonly used experimental animals in numerous biomedical researches, as they have been recognized as the preeminent model mammalian system. But, the precise correlation between age of laboratory rats. Young rats received from their 38th day of age a low-protein diet containing either casein 8 and brewer's yeast 3 per cent. or brewer's yeast 18 per cent. as source of protein. Littermates were weaned at different ages, i.e., 17, 19 or 20 and 25 days. The difference in survival time between rats weaned at 17 and those at 19 days was not significant, but rats weaned at 25 days survived.. But, this is actually the normal age mom will start to wean them herself without human intervention. Rats naturally wean between 3 and 4 weeks on their own. you could leave them there a few more days, so that they get a few extra days of nursing, but you could take them now if you truly wanted to only be used in altricial pre-weaning rodents (e.g. mice and rats, NOT guinea pigs) after the digits are no longer webbed and before they reach eight (8) days of age. Every reasonable effort should be made to minimize pain or distress, including limiting the number of digits clipped to one digit per rodent

Raising a Baby Mouse 6/10 Dehydration, Bloat - YouTube

AFRMA - Breeding & Stuff - Breeding Age of Rats; Weaning Mic

Ten rats were operated on while the other six served as controls. After surgery all were mated at 8-10 weeks of age. Gestational length was taken as 22 days. Rats were manually restrained for abdominal ultrasonography and were scanned daily from day 7 until day 19 or 20 post-mating followed by immediate euthanasia Cardiovascular Research Sciencedirect. Sprague Dawley Rat. High Fat T Increases Pain Behaviors In Rats With Or Without. Increased susceptibility of post weaning rats on high fat t to rat weight age chart buna digitalfuturesconsortium lifetime essment of tary nucleotides consumption in sprague sd an weights of sprague dawley rats and age table If male rats are handled by humans every day from day 1 to day 21 (weaning), puberty is delayed by 2.6 days (from age 42.0 to 44.6 days), probably by delaying the LH peak, which in turn delays the androgen peak (Korenbrot et al. 1977). Puberty: females: defined here as the time of vaginal opening (VO), also called vaginal patency Average and Range of Weights (g) of Commonly Used Strains of Mice*. Strain. Sex. 21 DAYS. 42 DAYS. 56 DAYS. 84 DAYS. MICE

(PDF) Post-Weaning Changes in the Digestive Physiology and

3 rats 400-499grams c) 4 rats 300-399grams d) 5 rats 200-299grams e) 6 rats 100-199grams f) 10 rats <100 grams g) 2 adult rats with 1 litter of pups until weaning age . 4) Maximum rat housing densities for Techniplast double decker cage 155 sq in bottom, 125 sq in. upper deck totaling 280 sq in a) 2 rats > 500 grams * b) 3 rats 400-499grams c Giovanne B. Diniz, Paulo L. Candido, Marianne O. Klein, Renato D. Alvisi, Françoise Presse, Jean-Louis Nahon, Luciano F. Felicio, Jackson C. Bittencourt, The weaning period promotes alterations in the orexin neuronal population of rats in a suckling-dependent manner, Brain Structure and Function, 10.1007/s00429-018-1723-0, 223, 8, (3739-3755.

IGS refers to CD rats bred using the CRL International Genetic Standard system. Color Breeding Age, Males (wks) Breeding Age, Females (wks) Mating Ratio Estrous Cycle (Days) Gestation (Days) Average Litter Size: 1st litter Average Litter Size: 2nd litter Birth Weight (gm) Weaning Weight, Males (gm) Weaning Weight, Females (gm) Weaning Age (days Weaning Mice and Rat Pups. When weaning pups into a clean cage, always place feed pellets that have been moistened with water on the cage floor to help initiate the weaning process. Even if the cage is to be placed on a rack with auto-watering attached, it is essential that the cage also is provided a water bottle Rats have a large horseshoe-shaped Harderian gland deep within the orbit. Secretions from the gland contain varying amount a reddish-brown porphyrin pigment depending on the physiologic state, age, strain and sex of the rat. The amount of secretions increases during stress and appears as 'red crusts' around the eyes and nostrils Newborns weigh an average of 5 grams and are milk-fed until weaning occurs at 3 to 4 weeks, and the young then leave the nest. ( Barnett, 1963 ; Calhoun, 1962 ; Parker, 1990 ) Often, the litters of numerous females will occupy the same nest, and all the young are cared for by the adults, regardless of who the true mothers are Breeding Age of Rats; Weaning Mice. Breeding Age of Rats. Laurel Summerfield, Burke, VA Q I had my first litter of nine baby rats, but I was worried that mom was not taking care of them properly because she was so stressed about being totally confined after semi-freedom

Rodent biology

Baby rat stages are Pinkies, Fuzzies, Crawlers, Hoppers and then at weaning age i call them littles. Many people call baby rats, kittens, puppies, Rittens or ratlettes. Some babies will start trying to drink the Mothers milk, even while she is still giving birth 7. Weaning. Gestation for mice and rats is approximately 21 days. The young are weaned at 21-28 days of age. Both mice and rats can breed as early as 8 weeks of age, thus it is imperative that the pups are separated by gender at an early age 3) Wean date - 21 days after date of birth 4) Include how many pups are weaned 5) If PACUC has given approval for extended weaning up to 28 days the cage card must be labeled with that information. Again, you must have PACUC approval to extend the weaning age past 21 days. If a secon There was essentially no difference in birth or weaning weight. But rat-tail calves gained 0.22 lb/day less from weaning to 12-months of age, 0.24 lb/day less from 12 months to slaughter at about 16 months, and were 79 lb lighter at slaughter, though they were fed for 13 more days Four litters were weaned at 21 days-of-age, and 4 at 30 days-of-age. After weaning, rats from half of each litter were allocated to individual cages in the rat colony. The other half of the litter was raised in same-sex sibling groups, 4-5 juveniles in each cage, so that weaning age was compared between litters whilst rearing condition was a.

Norway Rat Biology and Public Health SignificanceGambian pouched rat | The VALiens

AFRMA - Baby Rat Development from Birth to 6 week

Rosen et al. (1987) examined the effect of the age at first mating on litter size and weaning weight of Wistar rats. Maternal ages of 70 or 105 days resulted in larger litters and higher weaned weights, but also increased pup mortality, compared to dams bred at 35 days of age Lifespan. 2 to 5 years though some giant kangaroo rats have been known to live for over 9 years. Weight. 4.5 ounces. Height. 2 to 4 inches at the shoulder. Length. As long as 14 inches, with an 8-inch tail and 6-inch body. Males are larger than females Weaning. Weaning is another factor in determining when a pup can leave the litter. Most pups begin the gradual switch from their mother's milk to solid food anywhere from 3-to-5-weeks-old. The tiny Sprague Dawley pups are born naked, blind, and entirely dependent on their mother for survival. However, the first couple weeks of a rat's life are full of changes. The pup's eyes begin to open around 2 weeks and they begin to eat an adult rat's diet at around 3 weeks of age. By 4 weeks they are completely independent

Breeding Age - Rat Guid

Common Mistakes with Weaning-Age Baby Squirrels. Giving nuts, seeds, and fruits as the first solid food. Introduce blocks first, then veggies. Weaning off formula too soon. Keep the baby on formula until at least 14-16 weeks old. Allowing household pets near the baby. Your dog or cat will kill a baby squirrel in a second weaned rat, wean, rodent, rat, feeder, snake. Weaned Rats - Organically grown on site at our farm! Rats are available in a wide variety of sizes from pinky to jumbo adult and are a main staple feeder for carnivorous reptiles such as snakes and monitors Hence, the present study validated the effect of a bioactive flavanoid, fisetin, on MeHg developmental neurotoxicity outcomes in rat offspring at postnatal weaning age. Pregnant Wistar rats were simultaneously given MeHg (1.5 mg/kg b.w.) and two doses of fisetin (10 and 50 mg/kg b.w. in two separate groups) orally from gestational day (GD) 5.

Baby-led weaning. Baby-led weaning means giving your baby only finger foods and letting them feed themselves from the start instead of feeding them puréed or mashed food on a spoon. Some parents prefer baby-led weaning to spoon feeding, while others do a combination of both. There's no right or wrong way Rats pupsopened their eyes after 18 days ofage as they started to become less dependent on the dam rat. Atthetimeofkilling, milkwaspresentinthegut ofthese pups, but decreased in volume andconsist-ency by days 20-22. Byday 22, formed faeces was present in the distal small intestine and large intestine. BODYWEIGHTANDINTESTINALLENGT My co-workers and I (Galef, 1971; suggests that these bacteria may also be Galef & Clark, 1972) hav03previously found transmitted from dam to young without ex- that age of onset of weaning in rats is af- plicit ingestion of excreta by the infant Social Transmission of Food Preferences: An Adaptation for Weaning in Rats Bennett G. Galef, Jr. McMaster University, Hamilton Ontario, Canada Comparison of the extent of social influence on the feeding site selection of adult and weanling domesticated rats revealed that social interaction is a far more potent factor in determining the diet selection of weanlings than of adults

During weaning, autistic-like rats only exhibited obvious repetitive stereotyped behaviors, but the autistic-like behaviors were fully apparent upon sexual maturation. Significant differences were observed between the gut microbiota of autistic-like and healthy rats across both age groups weaning age on morphological changes that occur in rats' intestines, we assessed intestinal histomorphometry and somatic growth in 21 days old pups and 90 days old mature rats that had been weaned early (d16), normally (d21), or late (d26). Early weaning resulted in deeper crypts, lower villous/crypt ratio and a smaller villous area on day 21 Growth phenotype according to weaning age.Length and body mass index (BMI) of rats of F1 generation according to weaning age day (d) 16, 21 or 26: Males (A, C) and females (B, D) were measured for crown-tale length (A, B) and weight to give the BMI (g/cm2; C, D) from age d19 to 90.Statistically significant differences between d16 and d26 rats are indicated by (&) for P <0.02, (*) for P <0.001. • Requests for delayed weaning protocols must be pre-approved by the IACUC with specification of the actual weaning ages. Additionally, cages should be properly labeled by the PI to identify the group of rats approved for delayed weaning, with the approved weaning age stated on the label The effect of the weaning diet on the subsequent colonic metabolism of bran and pectin in the adult rat has been investigated. Feeding a fibre-reduced diet on its own or supplemented with bran (WB) and pectin (P) from weaning (fibre-reduced (weaning)) was compared with introducing the same diet to age-matched rats reared on a standard laboratory diet from weaning (fibre-reduced (6 weeks))

The obese-prone rats displayed higher NPY expression than the lean-prone rats at pre-weaning and weaning, and the expression levels did not differ by age. In contrast, POMC expression exhibited significant age-by-genotype differences This study describes a rat model of perinatal exposure to an HP diet during periods of gestation and lactation and after weaning up to 6 wk of age. The effects of the diets were sequentially characterized during the 3 periods. This study aims to represent reference data to test other experimental conditions Update: mother mice will continue to nurse their babies until they are three to four weeks old. It is best to continue offering formula every two to three ho.. Mating age: 6-8 weeks of age Gestation: ~19-21 days Wean age: ~21 days; up to 28 days if preferred Litter size: 2-12 pups; highly strain-dependent Replace breeders: ~7-8 months of age (several mutant strains have considerably shorter windows of optimal breeding performance) How to select appropriate breeding scheme

Baby Rats - A Guide To Baby Rat Care, Behavior and Developmen

-reach maturity at 6-8 wks of age-not bred until about 3 months of age-continuously polyestrus, spontaneous ovulators-male pheromones can cause the whitten effect -rats are born altricial, like mice-usually weaning happens at 21 Its metabolism is extremely low. The naked mole rat can live without oxygen for 18 minutes and live happily in an atmosphere of 80 percent carbon dioxide and 20 percent oxygen. It does this by accessing stores of fructose in its vital organs, including its brain. The naked mole rat is the only mammal that can do this The KO mice all died at 2-3 weeks (Aqeilan et al.2008), whereas a considerable number of the lde/lde rats survived after weaning (21 days of age) and died before maturation (Suzuki et al.2007). Postnatal earlier lethality in the KO mice seems to be related to their severely reduced serum levels of total protein,.

The Best Age To Get A Pet Rat (And Why) - Animal Knowho

Effect of weaning age on the small intestine mucosa of rat

2. The subchronic and chronic body weights are the time -weighted average (TWA) body weights for laboratory mammals over the period from weaning to 90 days (subchronic) and from weaning to 730 days postweaning (chronic). 3 From weaning to sexual maturity at around age 56-60 days, the rates at which young male rats pin each other to the ground become progressively asymmetrical -- eventually, one animal pinned the other on average 70% of the time, and his pins lasted longer too (Panksepp 1981) Rats are lively and intelligent creatures that can grow into great pets with the proper care and handling. At birth, baby rats, also called kittens, are only about 1 1 ⁄ 2 in (3.8 cm) long and are hairless, blind and deaf. They need to stay with their mother, who will nurse and care for them, for 4-5 weeks. After weaning, they require good nutrition, socialization, proper housing. A rat should be spayed or neutered at around three months of age. X Research source Spaying a female rat comes with several benefits, including a decreased chance of developing several types of tumors (breast, uterine, pituitary), and the prevention of pyometra (bacterial infection of the uterus). [27

Rats must be observed daily by trained personnel, with minimal disruption to the animals. Section 3.2 Personnel, p.23 4. PROCUREMENT Guideline 10: The health status of the incoming rats should be reviewed before the animals are shipped. Section 4.5 Reception of Rats at an Institution, p.27 5. BREEDING Guideline 11 Changes in breast-feeding patterns leading to eventual weaning often begin naturally at age 6 months, when solid foods are typically introduced. Some children begin to seek other forms of nutrition and comfort at around age 1. By this age, children typically eat a variety of solid foods and are able to drink from a cup Rat Reproduction . by Debbie The Rat Lady Ducommun . updated 12/27/13. Rats are very easy to breed. In fact, many people end up with unplanned baby rats! Rats can reach sexual maturity at 5 weeks of age, so the sexes should be separated at this age 3.1.2 Juvenile stock rats may be housed in groups of up to 12 rats (preferably as litter mates) until approaching sexual maturity (around 50 days of age) ( Lawlor 1987). 3.1.3 Ideally rat groups should be made up of litter mates of the same sex

• Weaning age. In a mouse husbandry context, weaning refers to removing a pup from its home pen (rather than to the time a pup stops nursing and starts eating solid food). Generally, laboratory mice are weaned between 18 and 28 days of age (Table 1). Weaning age depends on weanling size and maturity Weaning Investigators who choose to manage their own breeding colonies are responsible for timely weaning. Rats are generally weaned at 21 days of age. At 23 days of age, the PI will be notified if litters have not been weaned. The following day, these rats will be weaned by DCM for a $50.00 fee. Should delayed weaning Rats. Size: Rats are medium-sized to large rodents. However, rats may grow to be as long as 40 cm or more and weigh considerably more than mice. Color: Their coats are white, gray, brown or black in color and are often soiled enough to leave grease marks on touched surfaces. Head: The snout of the rat is more blunt than that of the mouse All Answers (35) Mice are considered infants from birth to 21 days of age. At that age they are weaned (prevented from nursing)—their mothers are removed from the cages. Mice are considered. How much adult rat terriers are fed depends on their age, size, build, activity level, and metabolism. Make sure to buy high-quality foods because the quality of dog food does make a big difference. Rat terriers owners should know that ratties have a tendency to be territorial with their food around other people and pets

process ensures timed-pregnant rats bear litters within a 24-hour window of your desired gestational age. When your research demands versatility and consistency, turn to the Sprague . Dawley ® outbred rat model. It is the most widely used rat model for biomedical research. Sprague . Dawley ® Rat. Regardless of the health . standard selected. Conventional rats directly after weaning and up to 30 days of age are less susceptible to experimental infection by strain Ny-1R than are older rats regardless of the test diet. The relationship between host age and susceptibility to infection is also demonstrable in ex-germfree rats fed a high-sucose diet a. As a method of identification of small rodents (mice and rats), toe clipping is best performed on neonates 5-7 days of age. Mice (not rats) may be toe-clipped up to 13 days of age. b. Written justification for toe-clipping must be approved by the IACUC before the procedure can be performed. The number of toes that will be clipped per anima

Rat Development Stages - Embryolog

Breeding and Reproduction of Rats - All Other Pets - Merck

Rodent Breeding: Rats Research Suppor

The study subjects were F 1 generation weaning rat pups of pregnant Wistar rats (Rattus norvergicus). Female Albino rats of the Wistar strain of 12-14 weeks of age and 180-200 g weight obtained from the Central Animal House, Dr. ALMPGIBMS, University of Madras, Taramani campus, Chennai-113, Tamil Nadu, India, were used for the study At the start of the study, i.e., weaning age of rats, basal glucose was 77 - 82 mg/dl both the groups. There was little change of fasting blood glucose in the ND-fed groups, however, almost a linear increase in fasting blood glucose was observed in HFD-fed groups. The value 103 ± 2.4 mg/dl crossed at 4-month and reached 108 ± 3.9 mg/dl at 6.

Rats as Pets - What to Know [Pros, Cons, Fact, CareRat Development - Embryology

Age of Weaning. 22 to 25 days. Lifespan. 2 to 5 years. Although some huge kangaroo rats have been recognized to live for over 9 years. Amazing Facts about the Kangaroo Rat. Kangaroo Rat Behavior. All kangaroo rats construct tunnels in soft or sandy soil. The tunnel system is quite intricate, and contains various living, sleeping, and food. mammals encounter a significant change in the composition of their diet at the time of weaning, coinciding with alterations in their digestive functions. Rat pups start to chew a solid diet at 15 days of postnatal age, and the gradual change from an exclusively milk diet to a solid diet rich in carbohydrates begins at 17 days of age ().In addition to the changes in the proportions of nutrients.

In rapidly growing juvenile rats, fatty rats are as insulin sensitive as lean rats at 4 wk of age but become increasingly insulin resistant as they became obese. During the suckling to weaning transition, fatty rats are insulin resistant at 2 wk of age, when they are exclusively suckling; they are also insulin resistant at 3 wk of age, when. Although the weaning age of 18 days was younger than the conventional 21-day weaning, rat weanling weights were comparable to a 21-day-old rat (≥40 g) (; see Fig 2C). Once weaned, offspring were weighed, housed with littermates, with no more than 4 siblings per cage, and given ad libitum access to food and water eight months (O'Riain M. J., 1996) or until two years of age according to Jarvis (1991a). After weaning, juveniles are rather roughly supervised by older siblings in a crèche-like environment. Stankowich & Sherman (2002) suggested that pup shoving by adult Naked Mole-Rats contributes to an adaptive alertness and defensiveness in adult behavior The present study examines sex differences in cortical thickness and in the dendritic tree of the monocular (Oc1M) and binocular (Oc1B) subfields in littermate male and female pairs of Long-Evans rats at weaning age (25 days.) From Nissl-stained tissue, it was found that the whole cortex and layer II-IV of Oc1B was thicker in males than females The present research was chiefly designed to determine the effect of the treatment of estrogenic agonist, estradiol benzoate (EB), or antiandrogenic compound, flutamide (Flu), at the weaning age on the expression of connexin (Cx) isoforms in the caudal epididymis of adult male rat.Animals were subcutaneously administrated with a single shot of either EB at a low-dose (0.015 µg of EB/kg body.

The study design incorporated 200 rats (100 Sprague Dawley and 100 athymic nude) that were maintained under SPF conditions (either isolator or barrier housing) before being euthanased at 3, 6, 12, 18 or 24 weeks of age. Two additional groups of 10 rats were housed within external facilities and euthanased at 12 weeks of age. Durin Protein-energy malnutrition affects children during their vulnerable age of development. Nutritionally balanced weaning foods are the key to attain optimal physical and mental development of the children. In this study, the biological value of proteins in cereal-legume weaning foods was investigated using rat bioassay The study design incorporated 200 rats (100 Sprague Dawley and 100 athymic nude) that were maintained under SPF conditions (either isolator or barrier housing) before being euthanased at 3, 6, 12, 18 or 24 weeks of age. Two additional groups of 10 rats were housed within external facilities and euthanased at 12 weeks of age