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At least 73 records · Page 4Linked to original sources
PubMed1991

The effect of genetic selection for milk yield on the response to growth hormone secretagogues in immature cattle.

Eighty 4-month-old calves of both sexes and of two selected lines differing by 70 kg in their predicted total yield of milk fat and protein were injected intravenously with three of four GH secretagogues: these were, per kg liveweight; (i) 0.2 micrograms human GH-releasing factor (1-29) (GRF), (ii) 0.2 micrograms TRH, (iii) a combination of (i) and (ii), and (iv) 0.1 g arginine hydrochloride. The response of GH was measured for 2 h following administration. Geometric mean concentration of the 5-, 10-, 15-, and 20-min samples following GRF, TRH and their combination were 29.3, 19.5 and 156 micrograms/l compared with baseline means of 6.5, 10.0 and 12.6 micrograms/l respectively, and for arginine (in which the mean response included the 30-min instead of the 5-min sample) 14.6 micrograms/l compared with a baseline of 8.31 micrograms/l. The line selected for greater yield responded more to each secretagogue by 1.53-fold following GRF (P less than 0.01), 1.34-fold following TRH (P less than 0.05), 1.11-fold following the combination (P greater than 0.01) and 1.26-fold following arginine (P less than 0.1). Females responded 2.3-fold more than males following GRF administration (P less than 0.001), only 1.2-fold more following TRH (P greater than 0.1), but less (0.63-fold) than males when GRF was combined with TRH (P less than 0.05). For all secretagogues the concentration of GH before administration was important in determining the size of response (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Genetic selection for diabetogenic traits in Yucatan miniature swine.

Yucatan miniature pigs have been selectively bred for reduced and increased glucose clearance during an intravenous glucose tolerance test. Pigs with low glucose clearance rates (low K) have been selected through the F-5 generation. They have a significantly reduced rate of glucose clearance and a blunted peripheral IRI increase in response to the challenge. Through the F-5 generation, heritability of glucose tolerance is estimated at 0.26. Sporadic fasting blood glucoses in excess of 100 mg/dl are seen in later generations of this group. High glucose clearance pigs (high K) have been selected through the F-4 generation. They have significantly increased rates of glucose clearance and a greater increase in peripheral IRI than the low K animals. The estimated heritability for high K through the F-4 generation is 0.31. No evidence of fasting hypo- or hyperglycemia has been seen in the high K animals.

Animals↗
PubMedDate not supplied

[Patterns of maternal behavior of rats genetically selected for opposite coping styles].

Maternal behavior of Koltushi High- and Low-avoidance (KHA and KLA) rats strains was assessed over the prewealing period (days 6-21). Ten litters of each strain were observed during the light phase of the light/dark cycle. In a series of experiments, rat pups were taken from the maternal nest and placed into the opposite corner of the cage. The following parameters of the maternal behavior were recorded: the latency of the first contact with the pups, pup licking, latency of carrying/retrieval of the first pup back to the nest, time of returning to the nest of the whole litter, and mother's spontaneous behavior (grooming and locomotion time) over the course of 10 min of observation. KLA mothers stayed with their pups and took care of them more frequently than KHA mothers during the light phase of the circadian cycle. Time of self-grooming was significantly higher in KHA rats. The highest levels of self-grooming of mothers was registered on the first day of testing. The latency of the first coming to pups after their removal from the nest was lower in KHA rats, but they needed more time to returned all pups to the nest. The experimental evidence suggests that the KHA but not KLA rats with the active coping style and higher stress reactivity display disorders in maternal behavior in a novel situation.

Adaptation, Psychological↗
PubMed1978

An improved procedure for genetic selection against hip dysplasia in dogs.

Rapid weight gain can educe hip dysplasia of dogs with normal hip joints. It is proposed that progeny whose parents have "excellent genotypes" would not be susceptible to this stress and would develop normal hip joints. The method for reducing the incidence of hip dysplasia in dogs would be to use stress to identify carriers (parents) and potential carriers (progeny), and select for breeding only dogs with proved genotypic value and those progeny with the best hip joint conformation.

Animals↗
PubMed1984

Genetic selection for tolerance to niclosamide and copper in Biomphalara glabrata (Mollusca: Pulmonata).

Successive generations of the PR-79 and M-line laboratory stocks of Biomphalaria glabrata were exposed in the LC90 of niclosamide or copper sulfate. Survivors from each generation produced the succeeding generation by self fertilization. The PR-79 stock showed no evidence of tolerance to either molluscicide following five generations of selection. On the other hand, M-line F5 snails demonstrated approximately two-fold higher tolerance to both molluscicides than did non-selected M-line snails.

Animals↗
PubMed1981

Genetic selection for small body size in Yucatan miniature pigs.

Yucatan miniature swine exhibiting smaller than average size and weight were selected as foundation stock for a miniaturization program. The F1 progeny from four matings of parent stock were evaluated based on weight through 24 months of age. Those animals with a mature weight at least 20% below the average of the population were selected as breeding stock for the succeeding generations. The selected F1 boars, when compared in size to the mean weight of unselected adult boars, were significantly lighter (p less than 0.01). Selected F1 sows were significantly lighter (p less than 0.001) compared to unselected sows of a comparable age.

Animals↗
PubMed1994

[The oxytocinergic neurosecretory system in genetically selected rats differing by their emotionality. Morphometric research].

The rats selectively bred for rapid (KHA) and slow (KLA) acquisition of the avoidance response were subjected to inescapable shock (IS). Synthesis and secretion of oxytocin (OT) were higher in intact KLA rats as compared to KHA ones. Preliminary exposure to IS resulted in opposite changes of the OT synthesis and secretion. The findings suggest a dependence of the stress-reactivity of the OT-ergic system on the copying of the behaviour strategy.

Animals↗
PubMedDate not supplied

[Genetic selection of mice for quantitative responsiveness of lymphocytes to phytohemagglutinin].

A two-way selection was performed in mice according to the quantitative response of small lymphocytes to the mitogenic activity of phytohaemagglutinin (PHA). The response of inguinal lymph node cells of each mouse to an optimal dose of PHA was measured by 3H-thymidine incorporation using a micro-plate method. Starting from four outbred mouse strains we mated on the one hand mice getting the best response and on the other hand mice getting the poorest response. A progressive separation of the two lines was observed. At the 7th generation a 3-fold difference was found between the two lines. A similar interline difference was observed when concanavalin A (ConA) was used as mitogen. The separation of the two lines was also evident when spleen cells or thymus cells were cultured with PHA or ConA.

Animals↗
PubMed1981

Ontogeny and interdependence of genetically selected behaviors in rats: avoidance response and open field.

Ontogeny and interdependence of genetically selected avoidance and open-field behaviors were investigated in six genetic lines, involving 1,018 animals, and three developmental models (longitudinal, cross sectional, and generational). In selected lines, behaviors varied with age, depending upon the genetic selection; in the control (random bred) line, no such effects were found. Between the lines selected for high (RHA) and low (RLA) rates of two-way-active avoidance, ontogenetic differences in the selected behavior emerged as the animals grew older, whereas between the lines selected for high (MR) and low (MNR) frequency of open-field defecation, the differences in the selected behavior were present at all stages of development. In unconditioned escape response to footshock, which shows an inverse relation to avoidance response in the RHA and RLA lines, and in general activity (number of sections crossed in an open field), which shows inverse relation to defecation in the MNR and MR lines, the differences were present at all stages. The relation between avoidance response and open-field defecation (emotional reactivity) was not linear but suggestive of curvilinear inverted-U-function.

Aging↗