Born Lambs Research Articles

Effects of certain environmental factors on growth performances of Kivircik lambs

Determining the growth performance of lambs is essential for producers to supply the lamb meat with the features demanded by the market as soon as possible. Therefore, the study aimed to determine the effect of year, birth type and sex of lamb on body weight and various body measurements of Kivircik lambs. Live weights of 612 Kivircik lambs (299 males and 313 females) were used in the study, which were born in 2014, 2015 and 2016. Body measurements of 47 male lambs and 50 female lambs, randomly selected from 508 lambs born in 2014 and 2016, were used in the study.
 Birth year had significant effect on both live weights and body measurements of lambs in various growth periods. Single born and male lambs are significantly superior in both live weight and body measurements over female and twin born lambs. This situation results in being preferred for both meat production and breeding purposes more than their opponents. In order to have a more productive herd structure, female and twin lambs should be reared according to their needs for a better growth performance.
 Rump height of single born lambs and chest depth of male lambs were higher than their counterparts throughout the study. Therefore, these two body measurements can be used as reliable parameters for investigation of growth performance of Kivircik lambs.

Histological Features of the Vomeronasal Organ in New Born Lambs (Ovis aries)

Background: vomernasal organ is an auxiliary olfactory organ which located at the base of nasal septumcomposed of olfactory epithelium and being enclosed by cartilaginous capsule. The current study was aimedto investigate the histological structure of vomernasal organ in new born lamb.Methods: six heads of new born lamb were used for this study. The nasal cavity including the hard palatewas sward up into four transvers sections. The sections were processed with paraffin embedding techniqueand tissue sections were stained with H&E stain.Conclusions: The rostral and middle portions of vomeronasals duct had medial and lateral walls with crescentshape lumen and enclosed completely by hyaline cartilage. The medial wall was lined with still diffentiatingneuro-epithelium, possessed many of intra epithelial capillaries and composed of supporting, bipolar neuron& basal cells. The lateral wall was lined with differentiating respiratory epithelium. The lamina propriasubmucosa beneath both neuro and respiratory epithelia composed of ruminant of embryonic mesenchymaltissue contained newly formed glands, blood vessels and nerves. A significant (p<0.05) difference wasrecoded between the diameters of the rostral, middle portions and caudal portion of both gender and therewere no differences between genders. The epithelial height of the neuro epithelia of the middle portion inboth gender had significant value (p<0.05) in compare with epithelia of other portions.

Phenotypic factors associated with lamb live weight and carcass composition measurements in an Irish multi-breed sheep population.

Understanding the phenotypic factors that affect lamb live weight and carcass composition is imperative to generating accurate genetic evaluations and further enables implementation of functional management strategies. This study investigated phenotypic factors affecting live weight across the growing season and traits associated with carcass composition in lambs from a multibreed sheep population. Four live weight traits and two carcass composition traits were considered for analysis namely; birth, preweaning, weaning, and postweaning weight, and ultrasound muscle depth and fat depth. A total of 427,927 records from 159,492 lambs collected from 775 flocks between the years 2016 and 2019, inclusive were available from the Irish national sheep database. Factors associated with live weight and carcass composition were determined using linear mixed models. The heaviest birth, preweaning, and weaning weights were associated with single born lambs (P < 0.001), however by postweaning, there was no difference observed in the weights of single and twin born lambs (P > 0.01). Breed class affected lamb live weight and carcass composition with terminal lambs weighing heaviest and having greater muscle depth than all other breed classes investigated (P < 0.001). Lambs born to first parity dams were consistently lighter, regardless of time of weighing (P < 0.001), while dams lambing for the first time as ewe lambs produced lighter lambs than those lambing for the first time as hoggets (P < 0.001). Greater heterosis coefficients (i.e., >90% and ≤100%) resulted in heavier lambs at weaning compared with lambs with lower levels of heterosis coefficients (P < 0.001). A heterosis coefficient class <10% resulted in lambs with greater muscle depth while recombination loss of <10% increased ultrasound fat depth (P < 0.001). Results from this study highlight the impact of multiple animal level factors on lamb live weight and carcass composition which will enable more accurate bio-economic models and genetic evaluations going forward.

Reproductive response to male joining with ewes with different allelic variants of the MTNR1A gene

The aims were to evaluate the reproductive response to ram placement with Sarda ewes with different allelic variants at position g.15099485 A > G of the MTNR1 A gene. Ram placements occurred between the early and late spring and there was analysis of whether this polymorphism is associated with other nucleotide substitutions. In each of the eight farms where the study was conducted (named F1-F8), 150 ewes (50 with A/A, A/G and G/G genotypes) were selected. In each group of 150 ewes, eight males were joined with ewes on the following dates: 25 March (T1) for F1-F2, 15 April (T2) for F3-F4, 5 May (T3) for F5-F6, and 1 June (T4) for F7-F8. The lambing dates and number of new born lambs were recorded until 220 days after joining rams with ewes. The ewes with G/G or A/G genotypes had a greater fertility rate compared with those with A/A in T1, T2 (P < 0.01), and in T3 and T4 (P < 0.05). The duration of time in days from the time of ram joining with ewes to lambing was less in the ewes with G/G and A/G compared with those with A/A (P < 0.01). The g.15099485A>G variation was always associated with that at position g.15099391G>A. Results indicate there is a positive effect of the g.15099485A>G variant on reproduction when males were joined with ewes in March or April. The association that was ascertained in this study between the g.15099391G>A and g.15099485A>G polymorphisms for the MTNR1 A gene, could provide new insights to clarify the mechanism of action of melatonin.

The sucking behaviour and milk intake of one- to three-week-old triplet lambs during natural and competitive suckling situations

Within triplet litters, light-born lambs are at greater risk of dying than heavier lambs in the first week of life. However, the implications of within-litter differences in sucking behaviour for milk intake and growth beyond the first week are unclear. We hypothesized that within litter, triplets born lightest would still be lightest at one to three weeks of age, that these lambs would have lower milk intake than heavier lambs, and that differences among lamb ranks (heaviest, medium, or lightest-born in litter) would be exacerbated in a competitive situation. Triplets in 10 litters were ranked according to birth weight and their sucking behaviour measured in two situations when they were 8–17 days old. In the morning session, undisturbed behaviour was recorded for 100min, after which the lambs were separated from the ewe for four hours. They were then returned to the ewe and competitive sucking behaviour was recorded for 15 min. Measures of live weight and abdominal girth were taken before and after each observation period to estimate milk intake. At 8–17 days of age, the lightest-born lambs were still lightest but the medium and heavy born lambs no longer differed in live weight (P=0.002). During the undisturbed period, heavy-born lambs sucked less often (P=0.026) and for less time overall (P=0.007) but gained similar live weight to their lighter siblings (P=0.299), indicating that they were more efficient at extracting milk. In the competitive session, light-born lambs tended to gain less live weight (P=0.086) and competed with the medium-born lambs for the teat not preferred by the heavy lambs (P=0.0005). These observations indicate that heavy-born lambs are efficient feeders, that medium-born lambs work harder to achieve the same milk intake, and that light-born lambs achieve lower milk intakes, contributing to their persistently lower weight. Thus, management strategies such as fostering or supplemental feeding should be focussed on the lightest-born triplets.

Body size estimation of new born lambs using image processing and its effect on the genetic gain of a simulated population

In this study the possibility of body size estimation of new born lambs using image processing and its effect on the genetic gain of a simulated population has been investigated. The body size of 158 new born lambs of Zandi sheep was evaluated via appraisal method, digital image processing and metric methods. The correlation coefficients between metric lamb size with quantities were calculated from image processing method and appraisal method were 0.88 and 0.48, respectively (P < 0.01). In the next step, two populations were randomly simulated using R2.15 programming environment, and two different scenarios based on two lamb size measurement methods were studied. In the first scenario, it was assumed that the animal body size is determined using image processing technique in continuous values, while in the second scenario it was assumed that the body size is determined via appraisal method in discrete values. As results, the accuracies of breeding value estimations in the first and second scenario were 0.89 and 0.78, and the genetic trends were 0.46 and 0.28, respectively (P < 0.01). The results showed that determination of lamb size based on proposed image processing method is feasible, and replacement of this new method instead of human appraisal method could increase the genetic gain in the breeding herds.

Associations between housing and management factors and reproductive performance in 327 Norwegian sheep flocks.

BackgroundHousing sheep in insulated, warm buildings, which is common in Norway, involves high buildings costs, but has not been reported to improve health and performance. Few studies have dealt with the association between housing and management and reproductive performance.Data on housing and management during the indoor period from a questionnaire were merged with herd level data from the Norwegian Sheep Recording System, and the material included 327 sheep flocks. Associations between housing and management factors and reproductive performance were analyzed by means of multivariate regression models and grouped logistic regression.ResultsThere was no difference in reproductive performance between warm and cold housing. Number of live born lambs born per pregnant ewe was highest in flocks with 10 or less ewes per pen, and lowest in flocks with more than 40 ewes per pen. Rate of barren ewes was lowest, and number of lambs per ewe at the end of the indoor period was highest in flocks where the sheep were regrouped according to number of foetuses (lambs) identified by scanning. A higher total number of lambs born per pregnant ewe and lambs per ewe at the end of the indoor period were found where other available housing facilities or outdoor areas were used in addition to the main housing unit in the lambing season. The rate of stillbirths was lowest on farms where sheep was the only animal production. None of the factors evaluated had any significant association with mortality of live born lambs in the indoor period. Lowest number of lambs per ewe at the end of the indoor period was found on farms where other family members/hired labour were caretakers as compared with the farmer or spouse/cohabitant, and highest numbers were found where caretakers were older than 60 years of age. Reproductive performance was lower in the Spæl Breed than the Norwegian White Sheep.ConclusionHousing systems per se are of minor importance, whereas management practices in the indoor period should be expected to improve reproductive performance.

Maternal influence on feeding site selection of male and female lambs

We conducted an experiment to determine whether early-life social learning of feeding site selection in lambs was sex-specific. Sixteen ewes and their new born lambs were used in a controlled experiment. Eight ewe–lamb pairs included a male lamb and the remaining eight a female lamb. All pairs were individually exposed to an experimental arena containing a safe and unsafe artificial feeding site (SFS, UFS) each consisting of nine bowls which contained either ground Bermuda grass hay (SFS) or ground alfalfa hay (UFS). The bowls in UFS were surrounded by bright orange traffic cones (visual cues). Half the ewes were trained with controlled electric shock to avoid UFS. Thus, pairs were randomly assigned to: (1) shock aversion training (SAT) to mothers of male lambs (MS); (2) SAT to mothers of female lambs (FS); (3) no aversion training (NAT, control) to mothers of male lambs (MC); and (4) NAT (control) to mothers of female lambs (FC). None of the lambs were subjected to SAT. During training, testing, extinction, and retraining ewe–lamb pairs were exposed to the arena together. Ewes were then removed from the experiment and two additional extinction phases were conducted with weaned lambs alone. Fear conditioning elicited UFS avoidance of both the trained ewes (means±s.e.m. % times observed in UFS during testing phase: FC=95.3±1.70; MC=94.4±4.87; FS=1.6±1.63; MS=0 ±0; P<0.01) and their naïve lambs (FC=83.8±6.07%; MC=76.6±6.56%; FS=30.4±7.90%; MS=33.9±9.23%; P<0.01). UFS avoidance in lambs occurred regardless of sex and tended to persist after weaning (% times observed in UFS during 1st post-weaning extinction phase: FC=92.6±4.50%; MC=89.8±6.09%; FS=45.1±10.57%; MS=43.5±10.42%; P=0.06). Fear conditioning in mothers appeared to alter sex-related differences in mother–infant behavioral synchrony by increasing and decreasing feeding synchrony of male and female lambs, respectively (FC: r=0.52, P<0.01; MC: r=−0.02, P=0.86; FS: r=0.14, P=0.26; MS: r=0.46, P<0.01). During the extinction phase mothers of ram lambs were observed feeding more often (FC=85.0±2.33%; MC=92.7±1.45%; FS=47.3±8.81%; MS=72±5.68%; P=0.02) and standing less often than ewes with daughters (FC=7.3±2.40%; MC=2.7±0.83%; FS=39.3±9.04%; MS=18.0±5.29%; P=0.06). This study suggests that social conditioning at an early age could be a viable tool to induce learning of feeding site avoidance in female and male lambs alike.

Non-Linear Regression Models to Predict the Lamb and Sheep Weight Growth

The study of living organism growth is the hot issue now a days in biological sciences. In thi s research, we explore the descriptive analysis of Lamb and Sheep weight growth in Pakistan. Also the non- linear regression models are identified on the basis of model selection criteria's for lamb and sheep weight growth prediction. From the analysis, we have found that for commercial sheep, spring born lambs and twin born lambs, the best model is the Von Bertalanffy model. While for predicting the weight of male commercial sheep, autumn born and single born lambs, the best model is the Brody model.

EFFECT OF ESTIMATED BY-PASS PROTEIN LEVEL IN CONCENTRATED RATIONS ON PERFORMANCE OF LACTATING AWASSI EWES PRE -WEANING

This study was conducted in Al-Rashidiya animal breeding station, using 6 ewes (2-6 yrs old) with average body weight of 42.7 kg with their single new born lambs, the ewes divided into 3 groups just after 4th week of birth. Ewes and their lambs. The ewes were paired randomly into three groups in cross over design with three periods each of 17 days , to investigate the effect of metabolizable protein: metabolizable energy in the rations (gm MP : ME MJ ). Three rations were used , the first consist mainly of barley, yellow corn, soybean meal and wheat bran(control R1 ).While the second ration R2 barley and wheat bran and third ration R3 also soybean meal were treated with acidic formaldehyde (9L/ton), the rations were iso calories and iso nitrogen but differ in MP : ME ratio which were 6.61 , 8.87 and 9.98 gm MP : MJ ME respectively . Results showed that feeding ewes on rations R2 and R3 significant (p

Familial episodic ataxia in lambs

HISTORY: A similar episodic neurological disorder occurred in new born lambs on two unrelated properties involving disparate breeds of sheep. Because of the number of lambs born, cross-breeding and the fact it occurred in some mating groups and not others, a dominant mode of inheritance was, initially and separately, suspected in each case. The sires of affected lambs were apparently normal. Whereas one was New Zealand Romney, the other was a composite breed with East Friesian genetics, but both rams originated from the same source property. To investigate the pathogenesis of the disorder these two rams were acquired and mated with unrelated sheep, under experimental conditions in a more controlled environment. CLINICAL FINDINGS: A proportion of lambs born to both sires exhibited a similar neurological disorder. Some lambs were noted to be abnormal at birth, both on home properties and in the experimental flock. They tended to adopt a head and neck extended posture and were slow to get to their feet and suckle when they then became more or less normal. When forced to move, they and other more robust lambs elicited an asymmetric gait, base-wide extensor hypertonia (hypometria) of thoracic limbs and flexor hypertonia (hypermetria) of pelvic limbs. In some there was nystagmus. After several metres of asymmetric ataxic gait they would fall to one side, sometimes adopting a sitting position. Recovery usually occurred in one to several minutes. As lambs aged, it became more difficult to elicit the episodes of dysfunction and by 6 months of age they appeared normal. DIAGNOSIS: The disorder was diagnosed as a dominant familial episodic cerebellovestibular ataxia inherited as a dominant trait, with incomplete penetration of observed clinical signs and variable expressivity. CLINICAL RELEVANCE: A proportion of affected lambs are likely to die in the neonatal period so the specific nature of the disorder may go unrecognised. Because of incomplete penetrance and varying expressivity, many of the lambs carrying this mutation will survive without showing clinical signs and may enter breeding flocks, where the disorder may be perpetuated and contribute to neonatal deaths.

Anti-acrosin antibodies in sera, colostrum and genital organs of vaccinated ewes: estimation and correlation with fertility.

Three ewes were vaccinated with boar sperm acrosin. Despite the presence of antiacrosin antibodies which crossreact with ram acrosin in the sera of the immunized sheep, no significant reduction in fertility was observed. Incubation of ejaculated or capacitated boar spermatozoa with anti-acrosin serum or IgG did not reduce the halos of digestion in the gelatinolysis test. However, an unexplained decrease of the forward progression and number of lytically active spermatozoa was observed after this treatment. We found antiacrosin antibodies and determined their titers in the sera of the vaccinated ewes, in colostrum and in aqueous extracts of cervix, uterus, oviduct and ovary. No antiacrosin antibodies could be detected in the sera of new born lambs. The immunoglobulins IgA, IgG and IgM were isolated from the sera of the ewes. The acrosin-specific antibodies belonged exclusively to the IgG class. In genital extracts the amount of IgG, IgA and IgM was determined. IgG was found in higher amount in every extract. IgA is present in similar amount only in the cervix, in the other parts only in traces. In all extracts IgM is found in a very low level. The specificity of the antibodies for acrosin was proven by active enzyme staining of the precipitin lines obtained by immunodiffusion.

Acute decrease of coronary flow after indomethacin delivery in newborn lambs

To document the effects of indomethacin (IND) on coronary flow. We studied nine premature lambs during the first day of life. The gestational age varied between 132 and 134 days (term 145 days) and weight 3.1-4.7 kg. Coronary flow velocities were recorded with an intracoronary Doppler guide wire in the proximal left anterior descending coronary artery (LAD). Average peak flow velocity was measured before, during and after an intravenous IND injection of 0.2 mg per kilogram of body weight. IND increased systemic blood pressure (p < 0.05) and rate pressure product (RPP; p < 0.05) indicating that IND increased cardiac workload. IND decreased coronary average peak flow velocity in all lambs (p < 0.05). The maximal fall in coronary velocity appeared after 3 min (range 1-7 min) and was regained 10 min (range 4-53 min) after the drug delivery. The maximal reduction of coronary average peak flow velocity was 52% (median 26). The recovery time was directly related to the maximal reduction of the coronary average peak flow velocity (R = 0.91, R(2) 0.84, p < 0.002). Coronary flow velocity decreased markedly in premature born lambs given a bolus dose of IND.

Cortical Excitatory Amino Acid Release and Cell Function during Hypotension in Near-Term Born Lambs

Background: Energy failure due to insufficient cerebral O₂-supply leads to excess accumulation of calcium ions in presynaptic neurons, followed by excess release of excitatory amino acids, which are potent neurotoxins, into the synaptic cleft. Aim:To investigate whether electrocortical brain activity (ECBA) can provide an adequate measure for excitatory amino acid release due to hemorrhagic hypotension. Methods: Ten near-term lambs were delivered at 127 days of gestation (term: 147 days). After a stabilization period, hypotension was induced by stepwise withdrawal of blood. Cerebral microdialysis was used to measure the concentrations of glutamate and aspartate. Results:During hypotension, mean arterial blood pressure, cerebral O₂-supply and ECBA decreased and the extracellular concentration of glutamate increased significantly. ECBA was significantly related to glutamate (R²: 0.67, p < 0.001) and aspartate (R²: 0.57, p < 0.001) concentrations. Conclusion:The extracellular release of glutamate and aspartate in the cerebral cortex increases after hemorrhagic hypotension in near-term born lambs. The extracellular overflow of glutamate and aspartate were significantly inversely related to ECBA.

Cerebral Cortical Tissue Damage After Hemorrhagic Hypotension in Near-Term Born Lambs

Hypotension reduces cerebral O(2) supply, which may result in brain cell damage and loss of brain cell function in the near-term neonate. The aim is to elucidate 1) to what extent the functional disturbance of the cerebral cortex, as measured with electrocortical brain activity (ECBA), is related to cerebral cortical tissue damage, as estimated by MAP2; and 2) whether there is a relationship between the glutamate, nitric oxide (NO), cGMP pathway and the development of cerebral cortical tissue damage after hemorrhagic hypotension. Seven lambs were delivered at 131 d of gestation. Hypotension was induced by withdrawal of blood until mean arterial blood pressure was reduced to 30% of normotension. Cerebral O(2) supply, consumption, and ECBA were calculated in normotensive conditions and after 2.5 h of hypotension. Concentrations of glutamate and aspartate in cerebrospinal fluid (CSF), NO(2) and NO(3) (NOx) in plasma, and cGMP in cortical brain tissue were determined in both conditions. CSF and brain tissue from siblings were used to determine normotensive values. Cortical neuronal damage was detected after 2.5 h of hypotension. ECBA was negatively related to the severity of the cortical damage. ECBA was related to respectively glutamate, NOx, and cGMP concentrations. In conclusion, cortical neuronal damage is detected after 2.5 h of hemorrhagic hypotension in the near-term born lamb. The damage is reflected by a reduction of ECBA. The glutamate, NOx, cGMP pathway is likely to be involved in the pathogenesis of cerebral cortical damage.

THE IMPORTANCE OF MOTHER CARE AND COLOSTRUM ON GROWTH RATES AND BODY MEASURMENTS IN AWASSI LAMBS

The growth and development in two groups of Aw-ssi lambs were followed from birth until weaning time. The first group did not received colostrum milk and divided in two equal sub group , the first was fed cow milk artificially, while the second sub group kept under mother care. Lambs in the control group (group 2) received colostrum and kept with their mother through - out the experimental period. &#x0D; Results indicated that lamb mortality was 20% in the first group while it was only 5 % in the control group. Average monthly body waight, body measurements and , weight at weaning time for lamb of the control group exceeded that of the first group and the differences were significant. &#x0D; Results also indicated that the second -sub-group showed better performance than the first sub-group although both of them received no colostrum , thus indicate the importance of mother care in the surviving of new born lambs

Welfare of the neonate lamb immediately after tail-docking

Tail docking of new born lambs is a routine practice in the United Kingdom. It has been used as a strategy to reduce the impact of myriasis (blowfly strike). There is only a limited period of time after birth (up to seven days) during which lambs can be docked without the use of anaethesia. Tail docking may have a detrimental effect on the ewe-lamb bond if the process leads to significant and sustained pain. French, Wall and Morgan (1994) suggested lambs suffer acute pain immediately after the procedure of docking but this potential disturbance of normal behaviour during the first few days of life did not seem to affect the long-term performance of lambs. The study reported in this paper considers the effect of tail docking on the behaviour of lambs during the first 90 minutes after docking and on lamb performance to slaughter.

Comparison of native and subunit antigens as ELISA reagents for the detection of antibodies against scabby mouth virus

A simple ELISA test to detect antibodies against scabby mouth virus (SMV) has been developed. Native whole virions and subunits of SMV generated by boiling the virus in the presence of sodium dodecyl sulphate (SDS) detergent and β-mercaptoethanol were compared as ELISA assay reagents using naive and hyperimmune sera from sheep and rabbits. Approximately 2 × 10 4 intact virus particles per microtiter well were required to generate a positive to negative signal of 0.8:0.3 ELISA O.D. units when the serum was used at a dilution of 1 100 . In contrast, total subunit antigen generated by disrupting and coupling of 250–500 virions per well provided a signal ratio of 1.58:0.3 ELISA O.D. units at a serum dilution of 1 250 . Total subunit antigens were therefore 400 times more economical to use than intact virions. In addition, subunit antigens could be readily bound to microtiter plates without the need for removal of the SDS. Secondly, it was not necessary to block non-specific binding sites on the plate with blockers such as gelatin and skim-milk, thereby shortening the time needed to complete the ELISA assay. The total subunit antigen ELISA test was used to detect seroconversion in new born lambs where there was an occurrence of SMV infection in housed sheep. Three bleeds were taken at fortnightly intervals and the ELISA results showed that 9 out of 15 lambs were seropositive for all bleed points. Four of the lambs showed a sequential rise in titer while only one lamb failed to seroconvert. The subunit ELISA test can therefore provide a very economical and sensitive test for the detection of antibody reactivity against SMV.

Lesions in finished early born lambs in southwest England and their relationship with age at slaughter

During a 2 year prospective study of 4413 early born housed lambs, from three flocks in southwest England, 3910 (88.6%) lambs were finished and 3718 (95.1%) of these were observed at the abattoir. The identity, age, carcase and pluck abnormalities and dead weight, conformation and fat classification of each lamb were recorded. Up to 20% of lambs had at least one abnormality. Pneumonia was the most frequent lesion observed with 10–15% of the lung tissue affected in the majority of lambs. Pleurisy, pericarditis and Cysticercus ovis infection were also observed in thoracic organs. In the carcase bruising, pleurisy, arthritis and C. ovis were the most frequent causes of rejection. Livers with haemorrhagic tracts thought to be related to parasite migration were observed. Prevalent lesions at slaughter of arthritis, pleurisy and pneumonia were associated with an increase in days to slaughter. The rejections and reduced growth rate were estimated to have cost the farmers £600–1500 per annum.

Cerebral function analysis during deep hypothermia and total circulatory arrest in infant lambs.

Deep hypothermia with total circulatory arrest is an important technique in the surgical treatment of complex congenital heart defects. However, the clinical use of this technique has been accompanied by occasional postoperative neurological abnormalities. Twenty new born lambs (four groups of five) were subjected to deep hypothermia (15 degrees C) and circulatory arrest for 30 min, 45 min, 60 min and 90 min respectively. Their brain electrical response was monitored by means of the Cerebral Function Analysing Monitor (CFAM), which produces a detailed analysis of the electroencephalogram amplitude and analyses the frequency of the waveforms into standard, beta, alpha, theta, and delta bands. After induction of circulatory arrest both the voltage and frequency recordings became isoelectric within 30-180 seconds and remained flat for the duration of the arrest. During the rewarming phase of the latency of time to initial appearance of electrical activity and continuous CFAM recording showed a good correlation with the duration of arrest and also a significant increase (p less than or equal to 0.001) when the circulatory arrest was maintained beyond 45 min. These findings suggest an increasing risk of neurologic damage when the arrest period is longer than 45 min.