Free-choice Method Research Articles

The Effect of Free Choice Whole Grain Wheat on Turkey Performance, Caecal Health and Foot Pad Dermatitis

This study was conducted to determine the effect of inclusion of whole grain wheat by a free choice method in the diet of turkey poults on bird performance, caecal health and foot pad dermatitis. A total of 192, four week old, as hatched, commercial line turkeys. Birds were blocked by live weight and then randomly allocated to one of two dietary treatments or whole grain wheat with starter pellet control (CON) treatment. Turkeys were offered their respective treatments for the duration of the study. Feed offered and refused and body weights were determined weekly. Turkeys were fed whole grain wheat (WGW) as free choice, it was observed that intake of WGW was much more variable in birds offered free choice WGW, although mean intake of WGW was greater. Bird performance was better if WGW was not fed. The weight of the (crop, gizzard, liver, pancreas and caecum) were not effect by treatment. Digesta pH was affected by treatment (P=0.045) gizzard digesta pH being lower when birds were offered WGW at 28-48 d old. Cecal content pH, cecal visual appearance scores, cecal content visual appearance scores, foot pad dermatitis were not affected by the WGW to the diet.

Cellular, Behavioral, and Locomotor Effects of Oral Nicotine in Male Rats with Bilateral Lesions in the Ventrolateral Striatum Induced with 6-OHDA

Objective: Parkinson's disease is a progressive neurodegenerative disease having a spectrum of non-motor to motor symptoms. Unrelated to motor symptoms of sensory, autonomic, and neuropsychiatric symptoms often appear early in the course of the disease. It is a remarkable observation that patients in the premotor phase can easily quit smoking without help. This study was intended to investigate the interrelation between nicotine and the partial loss of dopaminergic innervation in the ventrolateral striatum induced by 6-OHDA. 
 Methods: We used an experimental premotor parkinsonism model. The oral nicotine preference of rats was investigated with the two-bottle free choice method. The behaviors related to locomotor activity and emotional state were evaluated with a locomotor activity test, elevated plus maze, and forced swimming test. Histopathological evaluation was performed in the striatum by staining techniques using hematoxylin+eosin (H&E) and immunohistochemistry markers (caspase-3, and MAP-2).
 Results: Bilateral 6-OHDA lesions did not lead to a significant alteration in the total locomotor activity or nicotine preference. Nicotine increased horizontal but decreased vertical movements in addition to increasing anxiolytic but also depressive effects in the OHDA lesion group. The number of apoptotic cells was significantly lower in the lesion group receiving nicotine compared to those not receiving nicotine.
 Conclusion: Our experimental study points to the role of oral nicotine in male rats with bilateral striatal 6-OHDA lesions in the ventrolateral striatum. Further studies are needed to understand the relationship between loss of dopaminergic innervation in the striatum and nicotine consumption.

Varietal susceptibility of certain broad bean seeds to infestation with Callosobruchus maculatus (F.) and Callosobruchus chinensis (L.) (Coleoptera: Bruchidae)

Seeds susceptibility of eight broad bean varieties to Callosobruchus maculatus (F.) and Callosobruchus chinensis (L.) infestation were studied for the first time in free- and no-choice methods in the laboratory of Plant Protection Department, Faculty of Agriculture, Zagazig University. The relation between certain seed physical characteristics and some biological and and infestation parameters of both insects in the two studied methods were evaluated. None of these varieties were resistant to both insects, showing various levels of susceptibility. Biological and infestation parameters were significantly different among varieties except the developmental period. In free- choice method, Giza 3 was the most susceptible variety to both insects, since produced the highest progeny of 246.67 and 75.67 adults and susceptibility index (SI) of 10.25 and 7.42, respectively, while the least susceptible variety was Giza 716. In no– choice method, Nubaria 5 and Sakha 1 were the most susceptible varieties to C. chinensis, while Nubaria 3 and Giza 3 to C. maculatus. Differences between physical characters of varieties were significant. Seed hardness were correlated negatively and seed coat thickness positively with laid eggs, progeny and (SI) of both insects in free-choice method. Also seed coat thickness correlated positively with weight loss and seed damage (%) of C. chinensis and negatively of C. maculatus. To reduce seed losses the cultivation of the least susceptible variety (Giza 716) is encouraged and considered for breeding purposes to avoid insecticide usage.

Variations of Brain Functional Connectivity in Alcohol-Preferring and Non-Preferring Rats with Consecutive Alcohol Training or Acute Alcohol Administration.

Alcohol addiction is regarded as a series of dynamic changes to neural circuitries. A comparison of the global network during different stages of alcohol addiction could provide an efficient way to understand the neurobiological basis of addiction. Two animal models (P-rats screened from an alcohol preference family, and NP-rats screened from an alcohol non-preference family) were trained for alcohol preference with a two-bottle free choice method for 4 weeks. To examine the changes in the neural response to alcohol during the development of alcohol preference and acute stimulation, different trials were studied with resting-state fMRI methods during different periods of alcohol preference. The correlation coefficients of 28 regions in the whole brain were calculated, and the results were compared for alcohol preference related to the genetic background/training association. The variety of coherence patterns was highly related to the state and development of alcohol preference. We observed significant special brain connectivity changes during alcohol preference in P-rats. The comparison between the P- and NP-rats highlighted the role of genetic background in alcohol preference. The results of this study support the alterations of the neural network connection during the formation of alcohol preference and confirm that alcohol preference is highly related to the genetic background. This study could provide an effective approach for understanding the neurobiological basis of alcohol addiction.

Evaluasi Pola Konsumsi dan Cerminan Mikroflora Ayam Petelur Fase II dengan Pemberian Pakan Free Feeding Choiche

Penelitian ini bertujuan untuk mengetahui pengaruh pemberian pakan secara free feeding choice terhadap pola konsumsi dan cerminan mikroflora usus ayam petelur fase produksi ke-II. Penelitian dilaksanakan pada bulan Juni – Juli 2020 di kandang ayam petelur di Dusun Sidoharjo, Desa Sumbung, Kecamatan Cepogo, Kabupaten Boyolali. Materi yang digunakan yaitu 30 ekor ayam petelur Lohman Brown umur 52 minggu. Bahan yang digunakan dalam penelitian ini yaitu jagung, bekatul dan konsentrat layer khusus. Analisis data dilakukan secara kuantitatif dengan pembacaan grafik data yang diperoleh. Hasil penelitian menunjukkan bahwa ayam petelur fase II lebih menyukai pakan jagung dibandingkan dengan bekatul dan konsentrat. Konsumsi jagung yang tinggi mencapai 80 gr/ekor/hari. Rataan konsumsi pakan total cenderung rendah yaitu hanya 109 gr/ekor/hari. Penambahan jagung rata-rata sebesar 61 gr/ekor/hari sedangkan penambahan konsentrat rata-rata sebesar 28 gr/ekor/hari. Kondisi mikroflora usus halus dan usus besar didominasi oleh bakteri gram positif jenis Bacillus dan terdapat pula bakteri jenis Diplobacillus, Streptobacillus dan Streptococcus. Kesimpulan dari penelitian ini yaitu pemberian pakan menggunakan metode Free Feeding Choice mampu meningkatkan kesehatan saluran pencernaan serta meningkatkan HDP ayam petelur.

Active immunization against serum alcohol dehydrogenase normalizes brain dopamine metabolism disturbed during chronic alcohol consumption.

Chronic ethanol consumption in high doses is associated with constitutively elevated activity of the serum alcohol dehydrogenase I (ADH I) isoform, which demonstrates a high affinity not only for ethanol but also for a number of bioamine metabolites. Such excessive ADH activity is probably associated with disruptions in the metabolism of neurotransmitters (dopamine, serotonin, and norepinephrine) and subsequent long-term changes in the activity of their receptors. Ultimately, a stable depressive-like condition contributes to the development of patients' craving for ethanol intake, frequent disruptions during therapy, and low efficacy of treatment. We applied active immunization against ADH to investigate its efficacy in the reduction of excessive serum ADH activity and regulation of ethanol consumption by chronically ethanol-fed Wistar rats (15% ethanol, 4 months, free-choice method), and we analyzed its ability to influence the levels of bioamines in the brain. Immunization (2 injections, 2-week intervals) was performed using a combination of recombinant horse ADH isozyme as an antigen and 2% aluminum hydroxide-based adjuvant. The efficacy of immunization was demonstrated by the production of high titers of ADH-specific antibodies, which was consistent with the significantly reduced ADH activity in the serum of chronically ethanol-fed rats. On the 26th day after the first vaccine injection, we registered significantly lower levels of alcohol consumption compared to ethanol-fed control animals, and the difference reached 16% on the 49th day of the experiment. These observations were accompanied by data that showed reduced levels of ethanol preference in immunized rats. Chronic alcohol drinking led to a decrease in dopamine and DOPAL (a direct dopamine metabolite and a high-affinity ADH substrate) levels in the striatum,while immunization neutralized this effect. Additionally, we observed that inhibition of serum ADH activity caused a decrease in peak dopamine levels during acute alcohol intake in chronically ethanol-fed rats during ethanol withdrawal that was associated with reduced tyrosine hydroxylase activity in the striatum. The obtained data suggest a significant contribution of ADH to the changes in neurotransmitter systems during chronic alcohol consumption and make available new prospects for developing innovative strategies for treatment of excessive alcohol intake.

Effects of endophytic Beauveria bassiana (Ascomycota: Hypocreales) on biological, reproductive parameters and food preference of the soybean pest Helicoverpa gelotopoeon

ObjectivesWe studied Beauveria bassiana ability to endophytic colonize soybean and its effects on some biological and reproductive parameters and on the food preference of Helicoverpa gelotopoeon, a polyphagous plague of several agronomic crops. MethodsA suspension of 1 × 108 conidia ml−1 of B. bassiana (LPSC 1098), was inoculated in soybean plants using the leaf spraying method. H. gelotopoeon survival, developement, fecundity and fertility were registered to evaluate fungal effect. Also, food preference was determined by the free-choice method. ResultsB. bassiana as an endophyte adversely affected the duration of the larval stages (L1, L2, L3, L4) and of the adult stages, as well as the total duration of the life cycle. Furthermore, the oviposition period, fecundity and fertility of H. gelotopoeon decreased. This is the first report of decreased consumption of soybean leaves by H. gelotopoeon due to endophytic B. bassiana. ConclusionsThis investigation shows that endophytic fungi could be considered as useful microorganisms for the integrated pest management.

Tingkah Laku Makan Sapi Peranakan Ongole yang Diberi Pakan Berbasis Jerami Padi Amoniasi Dengan Metode Pemberian yang Berbeda

(Feeding behavior of local cattle fed based ammoniation rice straw with different feeding method)ABSTRACT. The objective of this study was to determine the effect of feeding methods on feeding behavior include the frequency and duration of eating time, the frequency and the duration of rumination for one day, night and daytime. The study used twenty of local cattle feeder males (Peranakan Ongole) with an age range of 1.5 – 2 years old and initial weight were 200-273 kg. They were fed randomly with four feeding methods of top concentrate, component feeding, total mixed ration (TMR) and free choice. Thus, completely randomized design was used for this study. Data length of eating and rumination time was analyzed using analysis of variance and continuities by honestly significant difference test (HSD). The frequency of eating and rumination were analyzed using Chi square. The results showed that the treatments affect significantly (P 0.05) on spent of eating night; rumination daytime and night spent, but had no effect (P0,05) on spent of eating one day, spent of eating daytime and spent of rumination for one day. Rumination frequency one day, daytime, and night were not affected (P 0.05) by feeding method. Night rumination of feeder cattle groups fed with TMR method were longer ( P 0.05 ) compared to feeder cattle groups fed with Component Feeding and Free Choice method, but it was similar ( P 0.05 ) to feeder cattle groups fed with Top Concentrate. Between the groups feeder cattle fed with Component feeding and Free Choice were not significantly different ( P 0.05 ).

Behavioral Characteristics of Ovariectomied Wistar Rats Trained in a Maze. Effect of Mental Stress and Castration for Infradian Rhythms

Four psychotypes differing by cognitive activity and psychoemotional reactions were distinguished in a population of orchiectomied Wistar rats and in a population of intact animals on the model of a complex cognitive test combined with the free choice method. With similar parameters of cognitive activity, the psychotypes of castrated rats were inferior to those of intact animals by the number of psychoemotional reactions and levels of locomotor activity. Infradian rhythms of spontaneous locomotor activity with a 4-day period were detected in intact and castrated rats. These rhythms did not change under the effect of mental stress, associated with food-getting behavior training, and did not depend on testosterone level.

FOOD PREFERENCE OF Microcerotermes diversus Silv. (ISOPTERA, TERMITIDAE) TO THE WOODS OF SOME FOREST TREES*

The result of feeding preference study of the termite Microcerotermes diversus Silv to the different species of wood tested ( Platanus orientals , Populus nigra , Cupresses sempervirens , Salix acmophylla ,, Pinus brutia and Eccalyptus camaledulensis ). Under both artificial and natural infection conditions. The insect preferred the wood of Platanus, Salix and Populus trees; the general mean of weight loss for wood during the period of experiment were: 65.95, 55.77, 26.35 and 37.85, 23.16, 37.74 gr. respectively, on the other hands Pinus and Cupressus wood showed loss preferred by the termite and gave 2.42, 2.89 gr. For natural infection and 4.95, 6.11 gr. for artificial infection respectively. The results obtained from study for wood preference and the free choice method emphasized the previous results.

Effects of fenfluramine, 8-OH-DPAT, and tryptophan-enriched diet on the high-ethanol intake by rats bred for susceptibility to stress

The swim-test susceptible (SUS) line of rats has been bred in our laboratory for the characteristic of reduced motor activity in the swim test following exposure to an acute stressor. Testing of multiple generations of SUS rats has also revealed that they consume large amounts of ethanol voluntarily. As reported for lines of rats that show a propensity for high-ethanol intake, the SUS rats show evidence of low serotonergic function. Because serotonergic function has often been shown to be involved in the regulation of alcohol consumption, here we examined the effects of manipulations of serotonin transmission on intake of ethanol by SUS rats. Fenfluramine, a serotonin-releasing drug, was injected at various doses (0.625, 1.25, 2.5, and 5.0 mg/kg) twice per day and ethanol intake was measured using a two-bottle free-choice method. The 8-OH-DPAT, a 5‑HT 1A agonist, was injected at various doses (0.03125, 0.0625, 0.125, 0.25, 0.5, and 1.0 mg/kg) before a 1-h session of exposure to ethanol (single-bottle test, water available the other 23 h per day). A diet enriched with 3% tryptophan (TRP), the amino acid precursor for serotonin synthesis, was administered in a restricted feeding schedule (5 h per day) with ethanol intake measured the last 4 h. Fenfluramine decreased ethanol intake at all doses tested. The 8-OH-DPAT increased ethanol intake at lower doses, presumably acting at autoreceptors, which inhibit serotonergic neurons, and decreased intake at higher doses, presumably acting at postsynaptic 5-HT 1A receptors. TRP-enriched diet also significantly decreased ethanol intake. Food and water intake were less or unaffected by these three manipulations. With all three manipulations, ethanol intake remained suppressed one or more days after the day of tests that decreased ethanol intake. These data suggest that SUS rats, like many other lines/strains of rodents that consume large amounts of alcohol, show an inverse relationship between serotonin transmission and voluntary intake of ethanol.

Availability Influences Initial and Continued Ingestion of Nicotine by Adolescent Female Rats

Background: The availability of tobacco products is associated with the likelihood that adolescents will begin using tobacco. Yet the relationship between nicotine availability and voluntary consumption has not been tested experimentally in developing rats. Method: The impact of environmental availability on adolescent female rats’ initial reaction to and continued ingestion of a novel solution (nicotine or control) was compared using a standard 2-bottle free-choice method and a multiple-bottle method. Results: Manipulating the ratio of bottles containing novel solution to water directly influenced the amount of both nicotine and control solutions consumed. Although subtle differences emerged in intake patterns with prolonged exposure, overall intake patterns were remarkably similar for nicotine and control solutions. Conclusion: The intake of oral nicotine was directly influenced by the availability of nicotine solution relative to water. The results indicate that simply providing the right environment is sufficient, and perhaps necessary, to increase rats’ voluntary consumption of a nicotine solution without relying on deprivation or sweetening of the solution. That overall intake patterns were comparable for nicotine and control solutions suggests that this may be a general principle of rodent behavior rather than an effect specific to nicotine.

Laboratory Evaluation of Dimethyl Phthalate against Anopheles stephensi and Culex pipiens

Two repellents includes Iranian and Merck dimethyl phthalate (DMP) were evaluated against Anopheles stephensi and Culex pipiens, using American Society for Testing and Material (ASTM) standard ED 951-83 procedure, a free choice method based on the variable dose-fixed time. Also a modified of ASTM method we used for determination of effective dosages of the repellents. In ASTM method there were no significant differences between the two repellents (Iranian and Merck's DMP) as indicated by the ED50 and ED95 values (p > 0.05). But, there were significant differences in repellent sensitivity between An. stephensi and Cx. pipiens at the ED95 level. In modified ASTM method there were no significant differences between the two repellents against An. stephensi, as indicated by the ED50 values (p > 0.05). But, there are significant differences between the two repellents against Cx. pipence based on ED50 value. Results of this study showed that the Iranian synthesized DMP has necessary potential and specificity to compare with Merck manufactured product.

Controlled Free Choice Method: A Proposal for a New Undergraduate Major Selection Policy at King Fahd University of Petroleum & Minerals

The prevalent undergraduate major selection at King Fahd University of Petroleum & Minerals (KFUPM) mostly depends on the student's choice regardless of academic abilities and qualifications. Owing to the adoption of this Free Choice Method (FCM), the number of students will continue to grow and external pressures at the national level may force the university to expand the admission intake every year, making it very difficult to expand and cut back programs as before. The accumulated effects threaten inefficiencies such as underutilization of some departments and majors. To address the immediate and subsequent negative impacts of FCM, this research proposes a Controlled Free Choice Method (CFCM) to ensure proper utilization of existing resources, reflect national needs in determining departmental capacities and stimulate student performance. The CFCM is based on student performance and preferences plus a cutoff GPA obtained in the orientation level in specific courses or all courses for each department. Under this procedure, departmental capacity will be determined prior to intake, thus maintaining the proactive nature of this approach. Finally, the CFCM is evaluated with respect to the limited scale responses of individual departments and colleges.

Intake of ethanol and reinforcing fluids in rats bred for susceptibility to stress

Rats have been selectively bred in our laboratory based on how swim-test behavior is affected by stress. Following exposure to an acute stressor, active swim-test behavior is reduced in the swim-test susceptible (SUS) line but is not reduced in the swim-test resistant (RES) line. Earlier findings indicate that SUS rats have reduced central serotonin and dopamine levels relative to normal, random-bred (i.e., nonselected [NS]) rats and RES rats, suggesting that SUS rats might respond differently to reinforcing substances, particularly ethanol. We report here comparison of SUS, NS, and RES rats regarding consumption of ethanol. Also examined was consumption of saccharin, sucrose, and quinine. Testing involved a two-bottle, free-choice method of measuring intake of substances in a home cage. Intake of each substance was tested across a range of concentrations. The results indicate that the SUS rats, tested across 14 generations, consume markedly more ethanol than the other two lines; in fact, SUS rats consume amounts similar to that ingested by lines/strains of rats bred specifically for ethanol intake. Similar to other alcohol-preferring rats, SUS rats show an increased affinity for saccharin solutions and a marked increase in their total daily fluid intake when a sweet-tasting saccharin or sucrose solution is available. These results indicate that a propensity to drink alcohol occurs in a line of rats that were selectively bred, not for alcohol intake, but for vulnerability to stress.

The use of dried bakery products in a free-choice feeding method for small-scale broiler production

Waste material from bakeries is an unconventional energy feed source which is available in sufficient quantities for use in small-scale broiler production in South Africa. Small-scale broiler producers do not have access to the computer programs required to balance home-mixed rations. This investigation confirms that the use of dried bakery products (DBP) in a 2-stage, free-choice method can be used to compensate for this lack. A total of 570 day-old male broiler chickens was assigned to 3 feeding treatments: the control group was fed a 2-stage feeding programme using standard commercial starter and grower rations. The 2nd group received a commercial starter ration up to Day 7 and was thereafter given a choice of a commercial starter ration with normal salt content (0.35%) and DBP. The 3rd group was fed a commercial starter ration up to Day 7, then offered a choice of commercial starter ration with a lower salt content (0.1%) and DBP. The low salt alternative was used to test whether the higher salt percentage in DBP influenced the choice of feed by the birds. It was found that the control group consumed significantly more feed (P < 0.05) and was significantly heavier (P < 0.05) than the experimental groups. However, there was no significant difference between the 2 experimental groups, which indicated that salt content did not play a role in the choice of ration. Feed consumption by both experimental groups was about one-third less than the control group, but the profit margin, as calculated using gross margin analysis, was approximately 15 % higher. It was therefore concluded that dried bakery products can be profitably incorporated as an energy feed source, using the free-choice feeding method, in small-scale broiler enterprises.

The use of dried bakery products in a free-choice feeding method for small-scale broiler production

Waste material from bakeries is an unconventional energy feed source which is available in sufficient quantities for use in small-scale broiler production in South Africa. Small-scale broiler producers do not have access to the computer programs required to balance home-mixed rations. This investigation confirms that the use of dried bakery products (DBP) in a 2-stage, free-choice method can be used to compensate for this lack. A total of 570 day-old male broiler chickens was assigned to 3 feeding treatments : the control group was fed a 2-stage feeding programme using standard commercial starter and grower rations. The 2nd group received a commercial starter ration up to Day 7 and was thereafter given a choice of a commercial starter ration with normal salt content (0.35 %) and DBP. The 3rd group was fed a commercial starter ration up to Day 7, then offered a choice of commercial starter ration with a lower salt content (0.1 %) and DBP. The low salt alternative was used to test whether the higher salt percentage in DBP influenced the choice of feed by the birds. It was found that the control group consumed significantly more feed P 0.05) and was significantly heavier (P 0.05) than the experimental groups. However, there was no significant difference between the 2 experimental groups, which indicated that salt content did not play a role in the choice of ration. Feed consumption by both experimental groups was about one-third less than the control group, but the profit margin, as calculated using gross margin analysis, was approximately 15 % higher. It was therefore concluded that dried bakery products can be profitably incorporated as an energy feed source, using the free-choice feeding method, in small-scale broiler enterprises.

Self-Administration of both Ethanol and Nicotine in Rats

Self-administration of either nicotine (NIC) or ethanol (ETH) has been extensively studied. This study addressed for the first time the self-administration of both substances when offered together. Male and female rats of different ages were offered NIC and ETH using the two- or three-bottle free-choice method. When NIC and ETH were offered together at different concentrations to young male rats (about 45 days old), intake of NIC increased with increasing NIC concentrations, and intake of ETH increased with decreasing ETH concentrations, but these effects were independent of the presence of the second drug. These rats also consumed the same amounts of NIC or ETH regardless of whether offered individually or together. A prior choice of only NIC or ETH did not affect a subsequent intake of both drugs offered together. A choice of both drugs for 24 h for several days followed by a choice for only 2 h for several days showed the same intake of NIC but a decreased intake of ETH for the shorter period. Young female rats (about 45 days old) and older male rats (about 75 days old) consumed the same amounts of NIC but less ETH than did the young male rats. These results show that young male rats voluntarily consume NIC and ETH independently of each other and that preexposure to one drug does not affect the subsequent intake of both drugs in combination. The data also suggest that these drugs act on different reward centers which have to be ‘satisfied’ independently of each other.

Effects of malnutrition during early lactation on development and feeding behavior under the self-selection paradigm

Selection of food can be affected by several factors, and with the method of self-selection, qualitative changes in nutritional balance may be detected. The goal of the present study was to evaluate feeding preferences in weaning rats using three macronutrients (protein, carbohydrate, and fat), through a free-choice method, evaluating the alteration in their feeding patterns as compared with the previous nutritional status during the early lactation period. We analyzed the effects of protein restriction during lactation over the nitrogen balance after the weaning. The dams were assigned to one of two diet conditions (nourished or malnourished). At weaning, two pups from each litter were housed individually in metabolic cages, and they were maintained on self-selection under a free-choice paradigm and were provided with separate sources of macronutrients. The parameter for evaluating the nutritional effectiveness of the diets was nitrogen balance. We observed that protein intake tended to increase and consumption of carbohydrate and fat tended to decrease progressively during the 3 wk of experiment. In selecting their own food, growing rats and malnourished rats consumed a larger amount of protein than the other rats. Nourished rats selecting their diet had a larger nitrogen balance than nourished rats receiving a composed diet; no nitrogen balance difference was found between the self-selecting groups. Rats can choose an adaptive form when recovering from protein malnutrition.

Determinants of the Voluntary Consumption of Nicotine by Rats

The 2-bottle free-choice method was used to study the voluntary consumption of nicotine by rats. Rats consumed nicotine voluntarily at different, albeit quite consistent, amounts. Voluntary intakes were higher in younger than older rats, but were not affected by gender. A previously forced nicotine intake had no effect on a subsequent voluntary intake of nicotine in older but increased it in younger rats. Forced exposure to nicotine of pregnant and lactating rats did not increase the voluntary intake by their offsprings. Established free-choice drinking patterns of nicotine were not affected by a temporary forced intake of this substance. The 2-bottle choice proved to be a reliable method to study the voluntary intake of nicotine, and results suggest that nicotine is not ‘addictive’ per se, but that its use is apparently determined by the response of an individual rat to this substance.