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Biomedical subjects

S Leeson

Publications and source records attributed to S Leeson.

At least 37 records · Page 2Linked to original sources
PubMed2004

Muscle (pectoralis major) protein turnover in young broiler chickens fed graded levels of lysine and crude protein.

An evaluation of muscle (pectoralis major) protein turnover using the phenylalanine flood dose technique was assessed in broiler chicks fed graded dietary lysine levels with CP at 170, 210, 250, and 290 g/kg diet. Chicks at 21 d old were injected with 1 mL/100 g BW of a phenylalanine solution (120 micromol L-[ring-2H5)]-phenylalanine). Muscle protein gain was assessed in chicks at 19 and 23 d of age. No differences were found in weight gain at lysine levels higher than 1.22% of the diet. Dietary lysine levels affected fractional synthesis rate (FSR, %/ d) of muscle with 170 and 210 g of CP/kg diet but not with 250 and 290 g of CP/kg. However, there was increasing FSR with increasing diet lysine levels at 290 g of CP/ kg. Breast muscle protein deposition (absolute growth rate, AGR, mg/d) reached a plateau with 1.22% dietary lysine at CP levels of 170,210, and 290 g/kg diet, confirming the observation on gross muscle weight. In terms of absolute synthesis rate/AGR with minimal absolute breakdown rate (ABR), the diet containing 210 g of CP/kg with 1.22% lysine was the most appropriate for chicks to 21 d. Levels of lysine influenced protein synthesis more so than protein degradation. These data suggest that both protein synthesis and breakdown increase at levels of dietary lysine and CP above those required for maximizing growth.

Animal Feed↗
PubMed2004

The inadequate smear: does it matter?

The objective of this study was to quantify the incidence of underlying cervical intraepithelial neoplasia (CIN) among women referred for colposcopy with three consecutive inadequate smears. The design was a retrospective cohort study analysing data from a regional colposcopy database at Cervical Screening Wales. Women who were referred to all the colposcopy clinics in Wales with three consecutive inadequate smears, the third inadequate smear being taken between 1 April 2001 and 31 March 2002 constituted the study population. The results of the fourth smear taken at the colposcopy clinic after three consecutive inadequate smears, the worst biopsy results from any of the subsequent colposcopies and the relationship between the result of the fourth smear taken at colposcopy clinic and any histology result were the main outcome measures. The accuracy of the colposcopic opinion was also examined. Of the 433 women identified as having been referred because of three consecutive inadequate smears, 302 were linked to either a subsequent smear and/or a biopsy result. An adequate smear result was available for 85% of these women when the smear was taken in the colposcopy clinic; 77% were reported as negative and 8% were abnormal. Of the 347 women seen in the colposcopy clinic, high-grade CIN was seen in 3% and low-grade lesion in 8%. The sensitivity and specificity of the fourth inadequate smear test in predicting underlying CIN were 15% and 84% respectively, with a positive predictive value of 8%. The sensitivity and specificity of colposcopy in predicting histological CIN among patients with three inadequate smears was 70% and 49%, respectively, and the positive predictive value was 44%. This study raises the question as to whether three consecutive inadequate smears should be considered as an indication for colposcopy, or merely for a further smear to be taken in circumstances where there is a greater likelihood getting an adequate result.

Adult↗
PubMed2003

Effect of hens fed dietary flaxseed with and without a fatty liver supplement on hepatic, plasma and production characteristics relevant to fatty liver haemorrhagic syndrome in laying hens.

1. Two long-term experiments were conducted with Single Comb White Leghorn (SCWL) hens (line UCD-003) predisposed to fatty liver haemorrhagic syndrome (FLHS). The first investigated the effect of adding a fatty liver supplement to the diet of laying hens prior to the onset of lay, and continuing either until peak production or throughout 39 weeks into lay. The second experiment, lasting 9 months into lay, investigated the effect of adding a fatty liver supplement, with or without 100 g/kg dietary ground flaxseed, to the diet. Body weight, feed intake, plasma triglycerides (in experiment 2) and egg production were measured throughout the experiment. Liver weight, liver fat content, liver malondialdehyde (MDA) content and liver haemorrhage score and fatty acid content of liver fat (in experiment 2) were measured at the end of each experiment. 2. In experiment 1, hens given diets containing the fatty liver supplement had higher egg production and eggshell strength, but there was no difference in liver parameters including MDA content or haemorrhage score compared with controls. 3. At the end of experiment 2, hens on 100 g/kg flaxseed diets had lower body weight, liver weight, liver dry matter and fat content, and plasma triglyceride concentrations than hens given the control diets. 4. Liver haemorrhage score was positively correlated with liver weight, but not with liver fat content, plasma triglyceride concentration or liver MDA content. This suggests that reducing the liver lipid content or feeding fatty liver supplements may not be as effective in controlling FLHS as controlling the size of the liver.

Animal Feed↗
PubMed2003

Long-term effects of feeding flaxseed on performance and egg fatty acid composition of brown and white hens.

Two hundred fifty-six 18-wk-old Shaver White and ISA-Brown pullets were fed commercial diets containing either 0 or 10% flaxseed in order to study the long-term effects of feeding flaxseed on hen performance and egg production parameters. Performance was monitored over 10 consecutive 28-d periods. Flaxseed was introduced gradually at 28 wk of age and was maintained until hens were 53 wk of age, when flaxseed was gradually eliminated from the diet. Feed intake was less (P < 0.05) for hens fed flaxseed compared to those consuming the control diet. Flax-fed hens were also lighter (P < 0.05) compared to the control birds. Egg production, egg weight, shell weight, albumen height, and shell thickness were not significantly (P > 0.05) different for hens consuming 0 and 10% flaxseed; however, yolk weight was reduced (P < 0.05) in hens fed flaxseed. Both strains of birds fed flaxseed deposited significantly more n-3 fatty acids into their eggs. Sampling of livers at the end of the trial showed that hens fed flaxseed had a higher (P < 0.05) incidence of liver hemorrhages.

Aging↗
PubMed2002

Quantitative and qualitative feed restriction on growth characteristics of male broiler chickens.

Four experiments were conducted to evaluate the quantitative and qualitative feed restriction on the performance of male broiler chickens. In the first experiment, broilers fed identical pelleted diets were feed-restricted from 5 to 42 d by giving 95, 90, or 85% of the feed consumed ad libitum by control birds the previous day. In a second experiment, broilers were fed pellet or mash diets from 1 to 7 wk. In Experiments 3 and 4, broilers were feed-restricted to 90% of the ad libitum intake of a control group during different intervals. Results from Experiment 1 indicated that live body weight at 42 d was significantly different between unrestricted and restricted broilers (P < 0.01). A reduction in mortality was noted when feed intake was reduced (P < 0.05). In the second experiment, broilers fed mash had lower body weights and breast meat yields at 42 and 49 d (P < 0.05). Cumulative mortality at 42 and 49 d was reduced in broilers fed mash (P < 0.05). Results from Experiment 3 indicated that body weight and mortality were not significantly different (P > 0.05) at 42 d across treatments. There was a significant (P < 0.01) linear improvement on feed conversion at 42 d due to duration of feed restriction. Breast meat yield at 42 d was less in broilers subjected to mild feed restriction (P > 0.05) (Experiments 3 and 4). Broilers appeared able to recover from mild feed restriction, and there was always an associated reduction in mortality.

Animal Feed↗
PubMed2001

Lidocaine selectively blocks abnormal impulses arising from noninactivating Na channels.

Abnormal, repetitive impulse firing arising from incomplete inactivation of Na+ channels may be involved in several diseases of muscle and nerve, including familial myotonias and neuropathic pain syndromes. Systemic local anesthetics have been shown to have clinical efficacy against myotonias and some forms of neuropathic pain, so we sought to develop an in vitro model to examine the cellular basis for these drugs' effects. In frog sciatic nerves, studied in vitro by the sucrose-gap method, peptide alpha-toxins from sea anemone (ATXII) or scorpion (LQIIa) venom, which inhibit Na+ channel inactivation, induced repetitively firing compound action potentials (CAPs) superimposed on a plateau depolarization lasting several seconds. The initial spike of the CAP was unaffected, but the plateau and repetitive firing were strongly suppressed by 5-30 microM lidocaine. Lidocaine caused a rapid, concentration-dependent decay of the plateau, quantitatively consistent with blockade of open Na(+) channels. Early and late repetitive firing were equally suppressed by lidocaine with IC50 = 10 microM. After washout of lidocaine and LQIIa, the plateau and repetitive firing remained for > 1 h, showing that lidocaine had not caused dissociation of channel-bound alpha-toxin. These findings indicate that therapeutic concentrations of lidocaine can reverse the "abnormal" features of action potentials caused by non-inactivating Na+ channels without affecting the normal spike component.

Anesthetics, Local↗
PubMed2001

Developing a cancer genetics service in Wales: opinions of gynaecologists on the management of women at risk of familial ovarian cancer.

In Wales, a cancer genetics service has been developing since 1998. Gynaecologists play an integral role in the management of women with a family history of ovarian cancer and we were interested in investigating referral practice and management for relatives of patients with ovarian cancer among gynaecologists in Wales. In 1999, a postal questionnaire was sent to all gynaecologists. The response rate was 51%. The questionnaire contained structured questions about current provision and a number of hypothetical scenarios to explore referral patterns to the cancer genetics service. The results of this study showed that referrals varied widely among specialists, as did the numbers who required onward referral to cancer genetics. The offer of screening to women at high risk of ovarian cancer was consistent, although there were variations in how often it was offered and the age at which it was offered. Most gynaecologists were easily able to establish when it was appropriate to refer onwards to cancer genetics, differentiating between women at high or low risk. There was some confusion about women at moderate risk of ovarian cancer. This study demonstrated the need for clear referral guidelines in Wales. Guidelines have since been distributed to all general practitioners and specialists; however, continued monitoring and further evaluation of referral practices will be necessary.

Family↗
PubMed2001

Performance of broilers fed limited quantities of feed or nutrients during seven to fourteen days of age.

Three experiments were conducted with male broilers to study the effects of early life undernutrition. In all studies, treatments were represented by three or four replicate floor pens, each containing 30 to 40 birds. In Experiment 1, broilers were fed at 0.75 kcal ME/gBW0.67 for 4 d, 1.5 kcal ME/gBW0.67 for 5 d or 2.25 kcal ME/gBW0.67 for 6 d, all imposed beginning at 6 d of age. Birds were smaller following feed restriction (P < 0.01) although growth compensation occurred, and at 49 d all restricted birds were heavier (P < 0.01) than full-fed control birds. Improved growth was associated with improved feed conversion (P < 0.01), although carcass composition was unchanged. In a second study, birds were fed at 0.75 kcal ME/gBW0.67 for 3, 4, or 5 d, starting at either 4, 7, or 10 d of age. When feed restriction was applied early, or for shorter periods of time, growth compensation occurred (P > 0.05). With other more severe feed restriction, birds were smaller (P < 0.05) at 49 d compared to controls. Feed conversion was improved following prior feed restriction (P < 0.01, 0 to 49 d). In a third trial, broilers were fed a starter diet diluted with 50% oat hulls. Birds failed to consume enough of this diluted feed, and so were initially smaller. However 49-d weight was not affected (P > 0.05). When periods of 24-h feed withdrawal were imposed in conjunction with the diluted diets, birds were underweight at 49 d. It is concluded that physical feed restriction at 0.75 to 1.5 kcal ME/gBW0.67 imposed for 3 to 4 d in the second week of life currently presents the best option as a means of controlling broiler growth so as to improve feed efficiency.

Adaptation, Physiological↗
PubMed2000

Effects of menhaden oil and flaxseed in broiler diets on sensory quality and lipid composition of poultry meat.

1. Three hundred and thirty 1-d-old male broiler chicks from a commercial strain were allocated to 11 dietary treatments comprising combinations of flaxseed at 100 g/kg and menhaden oil (MO) at 7.5 or 15 g/kg. Birds were given the experimental diets 7 or 14 d prior to slaughter. Carcase omega-3 fatty acid profiles and sensory evaluations of different cooked meat portions were carried out. 2. Linolenic acid was preferentially deposited in dark meat and long chain omega-3 fatty acids in white meat. Breast meat sensory quality was not affected in birds given 100 g/kg flaxseed for 14 d (treatment 3), 7.5 g/kg MO for 14 d (treatment 5) or 100 g/kg flaxseed +0.75 g/kg MO for 7 d (treatment 6). In contrast, thigh meat sensory quality decreased in treatments 5 and 6. 3. Feeding flaxseed and MO to birds for just 7 d prior to slaughter resulted in significant omega-3 meat enrichment depending on their dietary concentrations. The linolenic acid and long chain omega-3 fatty acids showed preferential deposition in dark and white meat, respectively, which may affect the sensory quality of various portions differently.

Animal Feed↗
PubMed2000

Effect of dietary flaxseed, flax oil and n-3 fatty acid supplement on hepatic and plasma characteristics relevant to fatty liver haemorrhagic syndrome in laying hens.

1. Two experiments were carried out to investigate the effect of dietary flaxseed, flax oil and n-3 fatty acid supplementation (Dry n-3) on hepatic fat content, plasma triglycerides, hepatic haemorrhage score, egg production, food intake and body weight in an inbred line of Single Comb White Leghorns (UCD-003) predisposed to fatty liver haemorrhagic syndrome (FLHS) and normal SCWL hens. 2. Feeding diets containing 100 g/kg ground flaxseed, 40 g/kg flax oil, or 100 g/kg Dry n-3 reduced body weight and significantly reduced hepatic fat content compared to feeding the control diet with animal and vegetable oil as a fat source. 3. Hepatic malondialdehyde, an indicator of lipid peroxidation within the liver, was not significantly affected by dietary treatment. 4. Normal SCWL hens tended to have higher egg production, greater body weight, greater food intake and higher blood triglyceride concentrations than UCD-003 hens, although the strain effects were not significant. Liver weight as a percent of body weight was significantly lower in normal SCWL hens. Treatments by strain interactions were not found. 5. The result suggested that dietary flaxseed, flax oil and Dry n-3 decrease hepatic fat content and reduce body weight, 2 of the predisposing factors believed to contribute to FLHS onset. However, haemorrhages were still apparent in both strains regardless of treatment, indicating that other unknown underlying mechanisms may also be responsible for FLHS.

Animal Feed↗
PubMed2000

Endogenous gut nitrogen losses in growing pigs are not caused by increased protein synthesis rates in the small intestine.

The purpose of this study was to establish, using a flooding dose of L-[ring 2, 6-(3)H] phenylalanine, whether feeding pigs diets that induce high endogenous gut nitrogen losses (ENL) also increases protein synthesis rates in (PSR) the visceral organs. Twelve 18-kg Yorkshire barrows with catheters in the right and left jugular veins were fed for 3 wk either casein-cornstarch- (CC) or barley-canola meal- (BCM) based diets formulated to a similar digestible energy /crude protein ratio and designed to induce either low or high ENL, respectively. Pigs were infused with 10 mL/kg body weight of a 150 mmol. L(-1) phenylalanine solution containing 230 MBq. L(-1) labeled phenylalanine for 12 min and killed 20 min later. Plasma phenylalanine specific radioactivity (SRA) rose to a plateau value within 3 min of starting the infusion and did not change (P > 0.10) thereafter. Fractional rates of protein synthesis (K(s), %/d) based on SRA in plasma- or intracellular-free phenylalanine did not differ (P > 0.10) in all tissues except pancreas (P < 0.05). Diet affected K(s )in liver (P < 0.01) and colon (P < 0.05) but not in pancreas, duodenum, jejunum and cecum. Based on plasma-free phenylalanine SRA, liver K(s)were 85.4 +/- 11.0 vs. 60.5 +/- 5.2 (mean +/- SEM) in CC- and BCM-fed pigs, respectively; these values were 82.3 +/- 4.7 vs. 98.2 +/- 5.8 in the colon. The absolute amount of protein synthesis (g.d(-1)) was higher in the liver (P < 0.05) and pancreas (P < 0. 05) of the CC pigs compared to BCM pigs. No dietary effects were observed in all other organs (P > 0.10). The present results suggest that feeding growing pigs a BCM diet that induces high ENL does not affect PSR in the small intestine of growing pigs from which >50% of ENL originates.

Animals↗
PubMed2000

Effect of feeding hens regular or deodorized menhaden oil on production parameters, yolk fatty acid profile, and sensory quality of eggs.

An experiment was conducted to investigate whether feeding menhaden oil (MO) to hens affects egg weight, and whether using deodorized MO (DMO) could ameliorate decreased sensory quality of eggs (characteristic for hens fed high fish oil diets). Two-hundred twenty-four Single Comb White Leghorn hens were allocated to seven dietary treatments comprising either no fish oil, DMO, or regular MO (RMO) at 2, 4, and 6% in commercial-type diets from 19 to 55 wk of age. The data collected were analyzed in four experimental periods (i.e., 0, 2, 6, and 9 mo after feeding MO diets). The sensory evaluation of 2-wk stored eggs from hens fed the 2% RMO, 2% DMO, and control diets was undertaken. Egg weight decreased linearly with increasing MO in all periods tested (P < 0.05). The panelist's scores of aroma, taste, flavor, and acceptability of eggs from hens fed diets containing 2% of either RMO or DMO were lower (P < 0.05) than for control eggs. Greater aftertaste and off-flavors in these eggs were also detected. No differences in sensory quality (P > 0.05) for eggs from hens fed RMO vs. DMO were found. These results suggest that the deodorization of MO does not ameliorate the impaired sensory quality of eggs characteristic of hens fed MO.

Animal Feed↗
PubMed2000

Studies on the metabolizable energy content of ground full-fat flaxseed fed in mash, pellet, and crumbled diets assayed with birds of different ages.

Four experiments were carried out to determine the AMEn of ground flaxseed in chickens of different ages and to study the effect of feeding flaxseed in pelleted or crumbled diets on flaxseed AMEn. A corn-soybean meal basal diet was prepared, in which the energy-yielding ingredients were substituted with ground flaxseed at 5, 10, 15, or 20%. Experiments 1, 2, and 3 consisted of these five dietary treatments replicated six times using 9-d-, 6-wk-, and 79-wk-old birds, respectively. A total collection procedure was used to measure diet AMEn, and linear regression analyses were used to calculate the AMEn value of flaxseed for birds at different ages. Experiment 4 involved birds fed either a basal or a 10% ground flaxseed diet prepared as mash, pellets, or crumbles. The flaxseed AMEn values obtained with 9-d- and 6-wk-old chickens were 2,118 and 2,055 kcal/kg, respectively. These values contrast with those of Experiments 3 and 4, in which mature roosters were fed mash diets with AMEn values of 3,560 and 3,654 kcal/kg, respectively. In Experiment 4, a significant improvement in flaxseed AMEn was observed when diets were pelleted or crumbled (4,578 and 4,277 kcal/kg, respectively). We concluded that the difference in AMEn of flaxseed observed in young birds vs. that found in mature birds was likely due to a greater tolerance of the latter to flaxseed, with less evidence of diarrhea. Feeding flaxseed in pellet or crumbled diets can significantly increase AMEn value.

Animal Feed↗
PubMed2000

The effect of intermittent lighting on metabolizable energy intake and heat production of male broilers.

Experiments were conducted to compare the effects of an intermittent lighting (IL) schedule with repeated cycles of 1 h light and 2 h darkness with a continuous lighting (CL) schedule on the performance, ME intake, and heat production of male broiler chickens. Body weight gain and feed intake were temporarily reduced after the changing from CL to IL; however, they were significantly higher in IL vs CL chickens during the subsequent period of 3 to 6 wk of age. The IL chickens exhibited a higher ME intake at 6 and 8 wk of age than did CL chickens. Total heat production in IL chickens was higher than for CL chickens, although heat production during the dark period was less than that during the light period for IL chickens. The higher feed intake observed in IL chickens appears to explain the superior body weight gain in IL broilers in simple terms.

Animals↗
PubMed2000

Effect of dietary lipase enzyme on gut morphology, gastric motility, and long-term performance of broiler chicks.

Three experiments were conducted to test a previously described anorexic effect of graded dietary supplements of Pancreatic lipase enzyme on gut structure, gastric motility, and long-term performance of broiler chicks. In Experiment 1, dietary Pancreatic enzyme was used at graded levels of 0, 0.214, 0.429, 0.643, 0.857, and 1.071% to test the effect of this enzyme on gut structure, whereas Experiment 2 was designed to test its effect at 0, 0.268, 0.536, 0.804, 1.071, and 1.339% on gastric motility. The histological examination of the small intestine and a cineradiographic study of birds fed diets supplemented with lipase enzyme failed to detect any difference in gut structure, and there was no apparent adverse effect on gastric motility. Experiment 3 was conducted to test the effect of graded supplements of Pancreatic enzyme on performance of 300 male broiler chicks raised for 6 wk to determine whether the enzyme had any long-term effect on performance characteristics, especially feed intake. Only starter diets (0 to 21 d) were supplemented with 0, 0.375, 0.750, or 1.125% enzyme, and each diet was represented by three replicate pens of 25 male chicks each. Subsequent diets did not contain any enzyme. During the first 3 wk, increased dietary concentration of lipase enzyme caused a linear reduction of feed intake and body weight gain (P < 0.01). At 21 d the percentage weight of the liver was significantly greater with 1.125% enzyme (P < 0.01). However, added enzyme had no effect on 21 to 42 d or 1 to 42 d growth or feed intake (P > 0.05) or on the size of any internal organs examined at 42 d. Pancreatic enzyme has previously been shown to improve fat digestion and increase diet AMEn for young chicks fed animal-vegetable blended fats. These positive effects, however, are associated with marked anorexia, and from the present study, it seems that this effect was not related to physical changes in gut histology or in prolonged digesta transit time.

Animal Nutritional Physiological Phenomena↗
PubMed1999

The effect of dietary supplementation with 1,25-dihydroxycholecalciferol or vitamin C on the characteristics of the tibia of older laying hens.

Seventy-two-week-old Leghorn hens were fed a conventional corn-soybean meal diet, or comparable diets either devoid of all supplemental vitamins, or with additions of 5 microg/kg 1,25-dihydroxycholecalciferol [1,25(OH)2D3], or 100 ppm vitamin C. The diets were fed for up to 30 d, with periodic observation on bone characteristics of selected birds. With a vitamin-deficient diet it took 30 d to realize significant reductions (P < 0.05) in bone breaking strength and these birds had less bone ash as early as 15 d (P < 0.05), although bone calcium content was not affected. Adding 1,25(OH)2D3 to the diet caused an increase in bone breaking strength after 15 d (P < 0.05) in the vitamin-deficient birds, although no difference was seen after 30 d. This increase in bone strength was associated with increase in bone cross-sectional area. Vitamin C generally had little effect on bone characteristics of the bird. These results suggest that there is little bone remodeling of older laying hens in response to short-term feeding of 1,25(OH)2D3 or vitamin C.

Animals↗
PubMed1999

Evaluation of dietary supplements of lipase, detergent, and crude porcine pancreas on fat utilization by young broiler chicks.

The purpose of Experiment 1 was to improve the digestibility of fat through the use of supplemental lipase enzymes. A 2 x 3 factorial arrangement of treatments involving two levels of animal-vegetable blend fat (AV) (4 and 8%) and three enzyme treatments, namely none; Pancreatic, 0.714%; and Pancreatin, 0.714%, were randomly allocated within a battery brooder. There was an increase in diet ME and apparent fat digestibility when Pancreatic and Pancreatin enzymes were used (P < 0.01). However, both enzymes caused lower feed intake and lower BW gain (P < 0.01). In Experiment 2, Pancreatic enzyme was used at graded levels of 0, 0.214, 0.429, 0.643, 0.857, and 1.071%, involving 4% dietary AV fat. The ME values were greater as the enzyme level increased (P < 0.01). However, as found in Experiment 1 lower feed intake and BW gain were observed with all enzyme levels compared with the control group. There was a linear effect on feed intake and BW gain (P < 0.01) and a quadratic effect on apparent fat digestibility (P < 0.05) and feed utilization (P < 0.01). Experiment 3 was designed to test the effect of Pancreatic enzyme at 0 or 1.339% in combination with two levels of detergent, namely 0 and 10% (with 4% added AV). The detergent used consisted of a mixture of 95% Span 60 and 5% Tween 60. In general, there was no significant effect of detergent (P > 0.05). Experiment 4 was conducted to test the effect of supplementation of graded levels of ground crude porcine pancreas at 0, 0.321, 0.535, 0.750, 0.964, 1.178, or 1.392% of the diet on performance of male broiler chicks to confirm the anorexic effect caused by supplementing with Pancreatic enzyme. In general, there was no significant effect of feeding crude porcine pancreas on the performance of male broiler chicks (P > 0.05). In these studies, lipase enzymes improved fat digestion, although it is suspected that associated reduced feed intake may be associated with contaminants such as cholecystokinin hormone.

Animals↗