Artificial Rearing Research Articles

Calcein Mark Retention in Chinook Salmon and Steelhead Fry in Artificial and Natural Rearing Environments

AbstractHatchery Chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss fry were marked with calcein dye to determine its efficacy for identifying fish after release into the stream environment. The effects of the dye treatment on growth and survival of marked fish and the retention of the marks over time were evaluated in the presence and absence of sunlight. Minimal differences in growth were observed between marked and unmarked Chinook salmon, and there was no difference in the total length of marked and unmarked steelhead at the conclusion of the study. Calcein marking had no effect on survival of Chinook salmon or steelhead fry during the 8‐week experiment. The calcein mark rapidly lost its intensity over time in Chinook salmon and steelhead. Steelhead fry were marked and reared in three light treatments to directly evaluate whether sunlight exposure affected calcein retention. After 28 d, steelhead exposed to sunlight had no visible calcein marks, whereas those held in covered tanks had 100% mark retention. Chinook salmon fry were monitored in stream habitats after release into the stream environment. No marks were visible 8 months after release. These observations demonstrate reduced calcein mark retention in fish exposed to natural sunlight. Calcein mark retention differed between Chinook salmon and steelhead. Because externally visible calcein marks have a finite life span in the presence of sunlight, calcein use in long‐term fish‐marking projects will be limited.

Impact of Artificial Rearing Systems on the Developmental and Reproductive Fitness of the Predatory Bug,Orius laevigatus

This study investigated the effect of several substrate types and moisture sources on the developmental and reproductive fitness of the zoophytophagous predator Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) when fed a factitious prey (i.e. unnatural prey) Ephestia kuehniella (Zeller) eggs, or a meridic artificial diet based on hen's egg yolk. O. laevigatus is known to feed on plants as an alternative food source and to oviposit in plants. E. kuehniella eggs were superior to the artificial diet. Supplementary feeding on plant materials did not compensate for the nutritional shortcomings of the artificial diet. Survival rates showed that oviposition substrates such as bean pods or lipophilic surfaces such as wax paper and plastic were more suitable for rearing O. laevigatus than household paper. The use of green bean pods as a plant substrate did not have a beneficial effect on O. laevigatus. The results indicated that O. laevigatus can successfully complete its nymphal development and realize its full reproductive potential in the absence of plant material. However, plant materials would still be required for oviposition, unless a reliable and cost-effective artificial oviposition substrate were made available. The omission of plant materials from the rearing procedures may reduce production cost of this species and other heteropteran predators.

Assessment of proteolysis and lipolysis in cheeses made using artisanal lamb rennet paste

AbstractRennet paste contains chymosin and pepsin as major enzymatic coagulant, and lipolytic enzymes such as pre-gastric lipase (PGL) and gastric lipase (GL), able to release free fatty acids during cheese ripening. Main factors influencing rennet paste features are diet (milk feeding, weaning) and slaughter age. Little is known about the effects of probiotic addition to milk substitute on the microbial and enzyme feature of rennet, and thus on the characteristics of cheese. In the present study the effects of different rennet pastes on the Pecorino foggiano cheese in terms of proteolytic and lipolytic characteristics were investigated. Twenty-four lambs were divided into six groups of four according to a 3x2 factorial design with lambs being subjected to three different feeding systems: mother suckling (MS), artificial rearing (AR), and artificial rearing with Lactobacillus acidophilus (Strain DSM 20079; DSMZ, Braunshweig-Germany; cells were suspended in milk replacer at the concentration of 7log 10 cfu...

Dietary Lactosucrose Affects Calcium Content in Scales of Juvenile Red Sea Bream Pagrus major under Artificial Rearing

Some dietary oligosaccharides increase bone calcium content, often depending on hind- gut fermentation of the saccharide in mammals. Dietary lactosucrose, an indigestible and ferment- able oligosaccharides, also stimulates osteogenesis in mammals. This sugar is also fermented by gut microbes of a teleost, red sea bream Pagrus major. However, we do not know the effect of this sugar on the calcium metabolism of teleosts. If dietary lactosucrose affects calcium metabolism in the fish, calcium content in the bone or scales should be modified by this saccharide. Therefore, we tested the effect of dietary lactosucrose on calcium content of vertebrae and scales in red sea bream under artificial rearing for four months. Since the lactosucrose product we added to the diet included 57% lactosucrose and 20% lactose, we added a lactose-fed group to elucidate the influence of lactosucrose by itself. Fish fed lactosucrose had lower body weight gain than those fed control or lactose diet. Fish fed lactosucrose had greater calcium content in scales than did control fish. However, fish fed lactose had greater vertebral calcium and indifferent scale calcium when com pared with control fish. The above results suggest that dietary lactosucrose, but not the associated lactose, increased calcium concentration in scales. It is likely that indigestible and fermentable sac harides such as lactosucrose increase calcium retention in the hard tissue not only in mammals but also in marine teleosts.

Observations of Oocyte Final Maturation and Eggs on Patin Pangasius hypophthalmus under Artificial Rearing Conditions

Observations of Oocyte Final Maturation and Eggs on Patin Pangasius hypophthalmus under Artificial Rearing Conditions

Observations of Oocyte Final Maturation and Eggs on African Catfish Clarias gariepinus under Artificial Rearing Conditions.

Observations of Oocyte Final Maturation and Eggs on African Catfish Clarias gariepinus under Artificial Rearing Conditions.

Effect of Complete Maternal and Littermate Deprivation on Morphine-Induced Fos-Immunoreactivity in the Adult Male Rat Brain

Previous research has demonstrated that rats reared in isolation from their dam and littermates show altered behavioral responsiveness to both natural and drug-mediated rewards. This study examined the effects of complete maternal deprivation through the use of artificial rearing on neural activation after acute morphine exposure in adulthood. Male rats were either artificially reared (AR) or maternally reared (MR) from postnatal day 5 to 21. In adulthood (4 mo old), rats received a single injection of morphine sulfate (10 mg/kg) or equivolume saline 2 h before perfusion and brain extraction. Neural activation was quantified using Fos immunohistochemistry. Analyses of several brain regions revealed a consistent pattern of differences between AR and MR rats. Specifically, relative to MR rats, AR rats showed significantly greater morphine-induced Fos-immunoreactivity in brain regions associated with the mesocorticolimbic "reward" pathway. These results support the hypothesis that functional activity in reward neurocircuitry can be altered by early life experience.

Motherless rats show deficits in maternal behavior towards fostered pups

Complete maternal deprivation in rats, through artificial rearing (AR), produces deficits in subsequent maternal behavior of the offspring. These deficits are partially reversed when isolated pups are provided with additional tactile stimulation designed to simulate maternal licking (e.g., Gonzalez et al. [2001] Developmental Psychobiology, 38, 11-32). These findings highlight the importance of the early maternal environment in subsequent development. However, given the possibility that prenatal environments may differ between AR and maternally reared (MR) offspring, the deficits in the behavior of AR mothers may be driven by the characteristics of their pups derived from the effects of an altered prenatal environment. Hence differences in the neonatal pups of AR mothers may produce the alterations in the AR maternal behavior. To rule out this possibility, we employed a fostering paradigm where AR and MR mothers received cross-fostered mother-reared pups. AR mothers showed the same level of deficits in maternal behavior towards MR foster pups as they do with their own pups and these deficits were partially reversed with additional tactile stimulation. Hence, maternal behavior deficits reported in mothers who had been reared in isolation are due primarily to the direct effects of the earlier experience on mechanisms regulating their maternal behavior and not to the effects on their offspring.

Effect of restricted suckling on milk yield, composition and flow, udder health, and postpartum anoestrus in grazing Holstein cows

The effect of restricted suckling on milk yield and composition, udder health, and postpartum anoestrus in dairy cows in pasture-based systems, was studied in 32 Holstein multiparous cows and their calves. At calving, each cow–calf pair was randomly assigned to one of two treatments: restricted suckling (RS) of the cows by her own or another calf, twice daily for 30 min or artificial rearing (AR) of the calves with milk obtained from the bulk tank, offered twice a day in buckets. Treatments were applied until week 8 after calving. The diet of the cows consisted of direct grazing in improved pastures, corn silage and a commercial concentrate which was offered at milking. Milk production and composition, udder health, body condition score of the cows, body weight and milk intake of the calves were measured weekly, and the first postpartum ovulation was determined three times a week by ovarian ultrasonography. Cows with RS management had a lower machine-milked milk yield (17.9 vs. 24.8 kg/d), a lower fat percentage (3.21 vs. 4.11%) and 4% fat-corrected milk yield (16.2 vs. 25.7 kg/d), and also a lower average milk flow (1.35 vs. 1.76 kg/min) than cows in the AR treatment. There was no effect of treatment on milk protein percentage or udder health as measured by milk electrical conductivity. The interval from calving to first postpartum ovulation was shorter in the AR cows than in the RS cows (18.5 vs. 21.8 days). The RS calves consumed more milk (7.2 vs. 5.4 kg/d), gained more body weight (0.813 vs. 0.656 kg/d), and had a higher body weight at weaning (84.3 vs. 73.3 kg) than AR calves. Restricted suckling of grazing dairy cows had a negative effect on machine-milked milk yield, fat percentage and 4% fat-corrected milk yield, but had no effect on udder health or on improved weight gain and body weight at weaning of the calves.

Artificial Rearing of Rat Pups Reveals the Beneficial Effects of Mother Care on Neonatal Inflammation and Adult Sensitivity to Pain

Repeated pain during brain development can have long-term consequences in both humans and animals. We previously showed that maternal care provided to pups experiencing pain reduced adult pain sensitivity. This study tested whether sensory stimulation was responsible for this effect. Rat pups were either mother-reared controls (MR-CON) or artificially reared (AR) with minimal (AR-MIN) or maximal (AR-MAX) stimulation provided daily. In each rearing condition, pups were either uninjected or injected from postnatal day (PND) 4 to 14 with saline (0.9%) or formalin (0.2-0.4%). Pain behavior and paw inflammation were scored. Thermal sensitivity and responses to formalin were tested in adulthood (PND 70). AR neonates, irrespective of sensory stimulation received, exhibited a pain response (p < 0.001), even with a mild formalin dose. Maternal rearing reduced inflammation during the second week of life compared with AR pups (p < 0.05). Early pain exposure did not modify adult pain sensitivity. However, rearing altered adult pain sensitivity such that uninjected MR-CON rats had lower pain sensitivities than uninjected AR rats (p < 0.05). This suggests that the beneficial effects of maternal rearing can be obliterated if additional stimulation/stress occurs during the early neonatal period. In addition, this suggests that optimal level of maternal stimulation exists that determines adult pain sensitivity.

Artificial Rearing of Infant Mice Leads to n‐3 Fatty Acid Deficiency in Cardiac, Neural and Peripheral Tissues

The ability to control the fatty acid content of the diet during early development is a crucial requirement for a one-generation model of docosahexaenoic acid (DHA; 22:6n3) deficiency. A hand feeding method using artificial rearing (AR) together with sterile, artificial milk was employed for feeding mice from postnatal day 2-15. The pups were fed an n-3 fatty acid adequate (3% alpha-linolenic acid (LNA; 18:3n3) + 1% 22:6n3) or a deficient diet (0.06% 18:3n3) with linoleic acid (LA; 18:2n6) as the only dietary source of essential fatty acids by AR along with a dam-reared control group (3.1% 18:3n3). The results indicate that restriction of n-3 fatty acid intake during postnatal development leads to markedly lower levels of brain, retinal, liver, plasma and heart 22:6n3 at 20 weeks of age with replacement by docosapentaenoic acid (DPAn6; 22:5n6), arachidonic acid (ARA; 20:4n6) and docosatetraenoic acid (DTA; 22:4n6). A detailed analysis of phospholipid classes of heart tissue indicated that phosphatidylethanolamine, phosphatidylcholine and cardiolipin were the major repositories of 22:6n3, reaching 40, 29 and 15%, respectively. A novel heart cardiolipin species containing four 22:6n3 moieties is described. This is the first report of the application of artificially rearing to mouse pup nutrition; this technique will facilitate dietary studies of knockout animals as well as the study of essential fatty acid (EFA) functions in the cardiovascular, neural and other organ systems.

Effect of artificial vs. natural rearing on milk yield, kid growth and cost in Payoya autochthonous dairy goats

Seventy full lactations of Payoya dairy goats were used to study the effect of two different kid-rearing systems, natural or artificial, on milk yield, composition, hygiene-sanitary quality, kid growth and rearing cost. Two animal groups were established, one with goats under natural rearing (NS) and the other under artificial rearing (AR). In the NS group, the kids had free access to goat milk 18–20 h a day and were suckled up to 5 weeks of age and then the dams were milked twice daily. Dams in the AR were separated from their kids at 48 h post-partum; then, kids were reared artificially, and the dams were milked twice daily. The number of animals used in each type of rearing system was 35 (23 goats giving birth to twins and 12 goats giving birth to a single kid). Each week during suckling phase the volume of milk produced was measured, and individual samples were taken. From 5th week and until 210 days lactation, test-day yields recorded at intervals of 30 ± 3 days were obtained. The chemical composition of the milk, the bacteriology, and the somatic cell count was analyzed. The kids of both sexes were assigned to two groups, natural suckling (NS, n = 58) and ad libitum artificial rearing (AR, n = 58). Within each treatment, two groups of kids were formed depending on prolificacy: first group with kids from single birth ( n = 12) and the second with twin kids ( n = 46). Birth weight and weight every week upto the 4th week of life were recorded. During the 5 weeks of lactation the total milk yield per goat was higher for the NS group (140.2 L vs. 95.4 L; P < 0.001), although the total amount of marketable milk was greater for the AR group, with a difference of some 21 L ( P < 0.05). Throughout the entire lactation the milk yield was higher in the group of natural rearing (total yield of 508 L vs. 400 L; P < 0.05). Although a significant effect of prolificacy was found during suckling phase ( P < 0.001), during 30 weeks of lactation this factor did not affect milk yield ( P > 0.05). For the milk composition and hygiene-sanitary quality there were no effects on the type of rearing system or the type of birth ( P > 0.05). No significant effect was observed either for the feeding system or the sex or the prolificacy on the live weight of the kids at 28 days and the postnatal growth rate from birth to 28 days ( P > 0.05). Natural rearing system had higher cost per kid comparing with artificial rearing system (€18.63/kid vs. €14.70/kid, respectively). However, when comparing total incomes during a full lactation, goats with natural rearing system had a higher income because of increment of total milk production (€29.95/kid).

GREATER CORTICAL THICKNESS IN PATIENTS WITH FIRST-EPISODE SCHIZOPHRENIA WHO ARE RESPONSIVE TO ATYPICAL ANTIPSYCHOTICS

Dopamine systems can be altered by experiences such as early life adversity. The intensity of these effects seems to vary as a function of interactions between genetic and environmental influences. In a series of experiments we have investigated the effects of genetic variants and early life adversity on several biobehavioral outcomes. Here we investigated the presence of single nucleotide polymorphisms (SNPs) in the gene coding for dopamine D2 receptors (DRD2) and the interaction between these variants with early life adversity on the expression of D2 receptors in the striatum. Time-mated pregnant female rats underwent restraint stress (gestational days 10–21) or were left undisturbed. Following parturition rat pups were maternally reared (MR) or artificially reared (AR). Subsequent to adult behavioral testing, rats were genotyped and their brains were processed (autoradiography) for D2 receptor expression. We found three variants in the DRD2 gene and these variants interacted with early adversity to affect D2 receptor expression in the nucleus accumbens. Specifically, artificially reared rats with AG DRD2 variant showed significantly higher D2 expression compared to mother reared rats with the AG DRD2 variant as well as the artificially reared rats with a GG DRD2 variant. These findings show that adult D2 expression is significantly influenced by the interaction of DRD2 SNPs and early developmental factors. These finding may explain why there are significant individual differences in the impact of early life adversity on dopamine-dependent processes and disorder vulnerabilities.

The effects of early isolation on sexual behavior and c‐fos expression in naïve male long‐evans rats

Previous findings have demonstrated that the maternal environment is important for the development of male sexual behavior. The present study examined the effects of complete early life isolation and replacement 'stroking' stimulation on male sexual behavior and neural activation as seen by Fos immunoreactivity (Fos-IR). Animals were either artificially reared (AR) with minimal (AR-MIN) or maximal (AR-MAX) body simulation, or maternally reared (MR). In adulthood, animals were either given an exposure to an estrous female (EXP) or left undisturbed (NoEXP). No significant effects of early development were found in sexual behavior; however differences in activation in response to this exposure were observed. AR-MIN animals showed lower Fos-IR in the medial preoptic area and the ventromedial hypothalamus compared to MR animals. AR-MAX animals were not significantly different from either condition. These findings demonstrate that although there are no differences in the quality of the first copulatory exposure between AR and MR animals, the brain's response to this exposure differs in sites within the brain that subserve sexual behavior.

Effect of suckling (‘restricted suckling’) on dairy cows’ udder health and milk let-down and their calves’ weight gain, feed intake and behaviour

The aim of this study was to evaluate the effects of restricted suckling (RS) in Holstein cattle on the weight gain, health and behaviour of calves and on udder health and milk let-down in cows compared to artificial rearing (AR). The study was conducted in Mexico. The 27 cows with calves were assigned to one of the two treatments and studied until weaning 8 weeks postpartum. Cows were milked three times daily. RS calves were allowed to suckle for 30 min 2 h after morning and afternoon milking, whereas AR calves were fed milk from buckets through a floating nipple at the same time. During suckling/milk feeding, the AR calves performed more oral behaviours such as ‘cross-suck’ and ‘lick object’ than RS calves. The RS calves spent a longer time suckling on the front teats than the rear teats. During observations of general behaviour when calves were not milk fed, AR calves displayed more often ‘cross-suck’, ‘lick object’, ‘eat concentrate’, ‘eat hay’ and ‘ruminate’ than RS calves. Milk consumption (286 kg) over 8 weeks in both groups and live weight gain (LWG) were similar in RS (26.2 ± 3.9 kg) and AR calves (26.1 ± 1.4 kg), but the individual variation in LWG was higher in RS calves. The milk suckled by RS calves contained more fat and metabolisable energy (ME) per kg than the parlour milk fed to AR calves (6.1% vs. 4.2% and 3.5 MJ/kg vs. 2.9 MJ/kg) whereas AR calves ingested more than fourfold as much concentrate as RS calves (21.6 kg vs. 4.8 kg), which resulted in similar total ME intake in treatments. The California Mastitis Test scores revealed a tendency to improved udder health in RS cows compared to AR cows. The average time to milk let-down was similar in treatments. In conclusion, the RS system with the Holstein dairy cattle reduced ‘cross-sucking’ and ‘licking objects’ in the calves and tended to improve udder health in the cows, compared to the AR system.

コアホウドリの人工飼育実験

コアホウドリの人工飼育実験

Experience-dependent cell survival in the maternal rat brain.

Postpartum maternal experience produces long-lasting changes in maternal behavior in the mother rat, which can be altered by early-life isolation. Postpartum experience also affects the regulation of adult neurogenesis in the neural circuit underlying maternal behavior, in a region-specific manner. Female rats were reared either with their mothers (MR) or in isolation in an artificial rearing (AR) paradigm. In adulthood, rats were mated and separated from their pups at birth. The following day, dams were injected with a mitotic marker and either allowed to interact with pups (maternal experience) or left alone. Results show that MR rats that acquire a later maternal experience show increases in cell survival in parts of the excitatory limb of the maternal neural network (bed nucleus of the stria terminalis and nucleus accumbens), but no changes in the inhibitory limb (amygdala). In comparison to AR inexperienced rats, AR maternally experienced rats show no increases in cell survival in the excitatory limb, but a striking reduction in cell survival in the inhibitory limb. The results suggest that early preweaning maternal isolation alters the structural plasticity that occurs following a postpartum maternal experience.

Prenatal restraint stress and motherless rearing disrupts expression of plasticity markers and stress-induced corticosterone release in adult female Sprague–Dawley rats

This study investigated the effects of prenatal stress and complete maternal deprivation, using the artificial rearing (AR) paradigm, on the expression of neural plasticity markers and hypothalamic–pituitary–adrenal (HPA) axis responsivity to stress. Rats were exposed to stress during gestation (day 10–21) and postnatally were either artificially reared (AR) or mother reared (MR). AR involves complete separation of the pup from both the dam and the litter throughout the pre-weaning period. In adulthood, we measured levels of corticosterone (CORT) in response to restraint stress. Also, we examined the expression of synaptophysin (SYN) and brain-derived neurotrophic factor (BDNF) in the medial prefrontal cortex (MPFC) and the nucleus accumbens (Nacc), areas of the brain that mediate behavioral activation and attention, among other behaviors. Earlier work on the same rats indicated that these behavioral endpoints, such as locomotor activity and sensorimotor gating, are affected by our prenatal and postnatal manipulations. Prenatal stress decreased CORT at 20 and 90 min post-stressor in MR, but not in AR, animals. Also, in comparison to MR groups, AR decreased SYN and BDNF expression in the MPFC and Nacc. Additional somatosensory ‘licking-like’ stroking stimulation partially reversed the effects of AR. Prenatal stress did not have a robust main effect but affected the impact of the postnatal rearing condition on SYN expression and stress-induced CORT. These results suggest that both prenatal and postnatal adversities have an influence on HPA axis responsivity and alter the expression of plasticity related neuronal proteins.

Maternal isolation alters the expression of neural proteins during development: ‘Stroking’ stimulation reverses these effects

Rat pups reared apart from their siblings, mother, and nest environment in the ‘pup-in-a-cup’ regime show many alterations in behavior reminiscent of the Institutional Inattention/Overactivity Syndrome that characterizes children whose first few months are spent in institutions. In this report, we compare mother-reared (MR) and artificially reared (AR) male rats in concentrations and distributions of brain proteins that are involved in normal brain development. When assessed during the juvenile period and in adulthood, AR animals showed elevations in Neu-N (a neuronal marker) and in S-100 (an astrocyte marker) but reductions in synaptophysin (synapse protein), N-CAM (cell-adhesion molecule), GAP-43 (axon elongation protein), and BDNF (brain derived neurotrophic factor) in comparison to MR controls in many brain sites involved in attention, impulsivity, activity, and social behavior. Daily ‘licking-like’ stimulation provided to AR animals (AR-MAX) throughout early development that reverses many of the behavioral deficits, also reverses many of the isolation effects on brain proteins. Study 2 showed that elevations in the number of neurons in combination with decreases in functionality are associated with a reduction in neuronal pruning and apoptosis during the very early post-partum period in AR animals and their reversal through daily ‘licking-like’ stimulation.

Docosahexaenoic acid and n-6 docosapentaenoic acid supplementation alter rat skeletal muscle fatty acid composition

BackgroundDocosahexaenoic acid (22:6n-3, DHA) and n-6 docosapentaenoic acid (22:5n-6, DPAn-6) are highly unsaturated fatty acids (HUFA, ≥ 20 carbons, ≥ 3 double bonds) that differ by a single carbon-carbon double bond at the Δ19 position. Membrane 22:6n-3 may support skeletal muscle function through optimal ion pump activity of sarcoplasmic reticulum and electron transport in the mitochondria. Typically n-3 fatty acid deficient feeding trials utilize linoleic acid (18:2n-6, LA) as a comparison group, possibly introducing a lower level of HUFA in addition to n-3 fatty acid deficiency. The use of 22:5n-6 as a dietary control is ideal for determining specific requirements for 22:6n-3 in various physiological processes. The incorporation of dietary 22:5n-6 into rat skeletal muscles has not been demonstrated previously. A one generation, artificial rearing model was utilized to supply 22:6n-3 and/or 22:5n-6 to rats from d2 after birth to adulthood. An n-3 fatty acid deficient, artificial milk with 18:2n-6 was supplemented with 22:6n-3 and/or 22:5n-6 resulting in four artificially reared (AR) dietary groups; AR-LA, AR-DHA, AR-DPAn-6, AR-DHA+DPAn-6. A dam reared group (DAM) was included as an additional control. Animals were sacrificed at 15 wks and soleus, white gastrocnemius and red gastrocnemius muscles were collected for fatty acid analyses.ResultsIn all muscles of the DAM group, the concentration of 22:5n-6 was significantly lower than 22:6n-3 concentrations. While 22:5n-6 was elevated in the AR-LA group and the AR-DPAn-6 group, 20:4n-6 tended to be higher in the AR-LA muscles and not in the AR-DPAn-6 muscles. The AR-DHA+DPAn-6 had a slight, but non-significant increase in 22:5n-6 content. In the red gastrocnemius of the AR-DPAn-6 group, 22:5n-6 levels (8.1 ± 2.8 wt. %) did not reciprocally replace the 22:6n-3 levels observed in AR-DHA reared rats (12.2 ± 2.3 wt. %) suggesting a specific preference/requirement for 22:6n-3 in red gastrocnemius.ConclusionDietary 22:5n-6 is incorporated into skeletal muscles and appears to largely compete with 22:6n-3 for incorporation into lipids. In contrast, 18:2n-6 feeding tends to result in elevations of 20:4n-6 and restrained increases of 22:5n-6. As such, 22:5n-6 dietary comparison groups may be useful in elucidating specific requirements for 22:6n-3 to support optimal health and disease prevention.