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PubMed2000

Antimicrobial susceptibilities of enterococci isolated from faeces of broiler and layer chickens.

Enterococci were isolated from faecal droppings of chickens in broiler and layer farms and the susceptibilities to nine therapeutic antimicrobial agents and six growth-promoting antibiotics were determined by the agar dilution method. Resistance to therapeutic antimicrobial agents such as ampicillin, clindamycin, erythromycin, streptomycin, tetracycline or tylosin was more frequent in enterococcal isolates from broiler farms than in those from layer farms. Resistance to ofloxacin was rare, occurring in only one (0.7%) of the Enterococcus faecium isolates from broiler farms. Resistance to growth-promoting antibiotics such as avilamycin, salinomycin and virginiamycin was common among isolates from broiler farms. Of the E. faecium isolates from broiler farms, 12.4% were resistant to avilamycin and 27.4% were resistant to virginiamycin. Resistance to salinomycin was detected in all enterococcal species, ranging from 12.4% of E. faecium isolates to 50% of E. hirae isolates.

Animal Husbandry↗

PubMed2001

Effect of energy source and xylanase addition on energy metabolism, performance, chemical body composition and total body electrical conductivity (TOBEC) of broilers.

Three diets containing either no supplemented fat (LF), 12% soybean oil (SO) or 12% coconut oil (CO) were fed to broilers to examine energy utilization in two experiments. Heat production and energy retained as fat and protein were measured in the first experiment using a respiration technique in combination with C- and N-balance and controlled (pair-fed) feeding conditions. Growth performance, carcass composition, chemical body composition and total body electrical conductivity (TOBEC) were evaluated in a second experiment under ad libitum feeding conditions (from hatching to day 35). Moreover, each of the three diet types was tested with or without the addition of a xylanase-containing enzyme preparation in the growth experiment. Energy utilization (experiment 1), expressed as the ratio between total retained energy and metabolizable energy intake, amounted to 0.33, 0.36 and 0.39 in LF-, SO- and CO-fed groups, respectively. Applying ad libitum feeding conditions in the second experiment caused a significant reduction in feed intake and weight gain in broilers fed the CO-diet. The feed-to-gain ratio was significantly lower in birds given the fat-supplemented diets. The highest degree of fatness as indicated by the highest percentage of abdominal and visceral fat and by highest total fat content was found in birds fed the CO-diet. The higher the body protein content and the lower the body fat content, the higher the TOBEC value should be. This was confirmed when LF-fed broilers were compared to their CO-fed counterparts. However, fat type seemed to be related to TOBEC values since SO-fed broilers had similar TOBEC values as CO-fed birds, whereas chemical body composition was comparable to LF-fed broilers. Xylanase addition significantly increased weight gain up to 21 days of age and decreased the feed-to-gain ratio slightly, whereas none of the other parameters were influenced by this treatment. An interaction between energy source and enzyme supplementation was not observed. It is concluded that feeding of coconut oil was most effective in terms of energy retention, but failed to induce an adequate performance under ad libitum feeding conditions due to a reduced voluntary feed intake. TOBEC measurements in relation to chemical body composition were rather inconclusive.

Animals↗

PubMed2001

Ameliorative effects of dietary clinoptilolite on pathological changes in broiler chickens during aflatoxicosis.

The amelioration of aflatoxicosis in broiler chickens was examined by feeding two concentrations of natural zeolite (clinoptilolite). Clinoptilolite (ClI), incorporated into the diet at 1.5 and 2.5 per cent, was evaluated for the ability to reduce the deleterious effects of 2.5 mg total aflatoxin (AF) kg(-1)diet on growing broiler chicks from 1 to 21 days of age. A total of 360 broiler chicks were divided into six treatment groups [Control, AF, CLI (1.5 per cent), AF plus CLI (1.5 per cent), CLI (2.5 per cent), and AF plus CLI (2.5 per cent)] each consisting of 60 chicks. Compared to controls, the AF consuming chicks showed increases in the relative weights of liver and kidney; and gross-histopathologic hepatic lesions such as paleness, friability, diffuse hydropic degeneration and/or fatty change, bile-duct hyperplasia and periportal fibrosis. Glumerular hypertrophy, increases in the number of mesengial cells and hydropic degeneration of tubuler epithelium in kidneys of chicks fed diet AF alone were also observed. Atrophy and lymphoid depletion were seen in the thymuses and bursa of Fabricius from the chicks fed AF alone. The additions of CLI (1.5 and 2.5 per cent) to the AF -containing diet moderately (significantly in some cases) decreased the number of affected broilers and/or the severity of lesions. The addition of CLI to the AF-free diet did not produce any significant changes compared with the controls. These results suggest that CLI was effective for the protection of AF-toxication in broilers and it could contribute to a solution of the AF problem in poultry production.

Aflatoxins↗

PubMed1985

The rate of degradation of myofibrillar proteins of skeletal muscle in broiler and layer chickens estimated by N tau-methylhistidine in excreta.

After N tau-methylhistidine (N tau-MH) distribution among the various organs or the tissues was determined in male broiler chickens of 15 d of age, the rates of degradation of myofibrillar proteins in male layer and broiler chickens at different stages of growth were determined by means of N tau-MH. About 75 and 8% of the total N tau-MH in the tissues occurred respectively in skeletal muscle and stomach, and most of the remainder in the intestine and the skin. The rates of degradation of myofibrillar proteins in the male layer and broiler chickens of 21, 42 and 63 d of age were calculated to be 6.1, 4.5 and 2.4%/d (layer) and 5.0, 2.8 and 0.9%/d (broiler) respectively. These calculations involve the assumption that 80% of the total excreted N tau-MH was derived from skeletal muscle. The results strongly indicate that the rapid growth of the broiler chicken is facilitated by the reduced rate of protein degradation.

Animals↗

PubMed2001

Effects of conjugated linoleic acid on growth performance, feed conversion efficiency, and subsequent carcass quality in broiler chickens.

The effect of dietary conjugated linoleic acid isomers (CLA) on growth performance, carcass composition, fatty acid composition of adipose and muscle tissues, and serum lipoproteins was investigated in broiler chickens. A total of 160 (eighty male and eighty female) chickens were allocated to four dietary treatments (0.0, 0.5, 1.0, and 1.5 % CLA) and fed a standard starter diet from 8 to 21 d, and a grower-finisher diet from 22-42 d. When determined for the total period 8-42 d, feed intake and body weight gains of broiler chickens were significantly reduced (from 3.31 to 3.12 kg and from 1615 to 1435 g respectively; P < 0.05), particularly at the 1.5 % dietary CLA level. Feed conversion efficiency and carcass yield values showed no significant effects of dietary CLA. Abdominal fat deposition was significantly reduced (from 2.68 to 1.78 %; P < 0.05), the relative proportion of breast muscles was unaffected, and that of leg muscles significantly increased (from 19.0 to 20.6 %; P < 0.05). The concentration of CLA isomers (% of total methyl esters of fatty acids) increased linearly in tissue samples from broilers fed 0.5, 1.0, and 1.5 % dietary CLA. The relative proportions of saturated fatty acids (16:0, 18:0) were significantly (P < 0.01) increased, and those of monounsaturated (16:1, 18:1) and polyunsaturated fatty acids (18:2, 20:4 in muscle tissues) significantly (P < 0.05) reduced. Total serum cholesterol concentrations reached a maximum in broilers fed 1.0 % CLA and then decreased slightly (from 141.73 to 136.47 mg/dl; P < 0.01). The same was true also for HDL-cholesterol (from 113.58 to 109.97 mg/dl; The HDL cholesterol:total cholesterol ratio and serum triacylglycerol concentration was unaffected. In conclusion, feeding CLA to broiler chickens resulted in substantial incorporation of CLA isomers into their tissue lipids, thus providing a potential CLA-rich source for human consumption.

Abdomen↗

PubMed2003

Safety assessment of Bt 176 maize in broiler nutrition: degradation of maize-DNA and its metabolic fate.

Insect resistant Bt 176 maize has been developed by genetic modification to resist European borer infection. In the present investigation, the experiment was conducted to determine the effect of feeding a new hybrid of Bt 176 maize (NX 6262- Bt 176) on general health condition and performance of broiler chickens. Maize grains and diets were subjected to proximate analysis. Amino and fatty acids investigation were applied for both maize grains before used. To evaluate the degradation of NX 6262- Bt 176 maize DNA and its metabolic fate in broiler blood, muscles and organs. One-day-old male broilers were fed ad libitum on either an experimental diet containing NX 6262- Bt 176 or a control diet containing the non-modified maize grains for 35 days. Feed consumption and body weight were recorded weekly during the experimental period. All chickens were subjected to nutritional evaluation period at day 20 of age for 5 successive days, to calculate the percentage of apparent digestible nutrients in both diets. At day 35 samples were collected at several intervals after feed withdrawal. Prior to slaughter blood samples were collected from all birds by heart puncture to prevent DNA cross contamination. Samples from pectoral and thigh muscles, liver, spleen, kidney, heart muscle, bursa and thymus glands were collected. Digesta from different sections of the gastrointestinal tract (GIT) were collected as well. Packed cell volume (PCV) and some serum parameters were investigated. There were no significant differences between control and experimental group concerning chemical composition of feeds, apparent digestible nutrients, and all performance parameters measured (P > 0.05). Furthermore, there were no differences in the PCV and the analysed serum parameters between the control and experimental group. The results of maize DNA digestibility showed that the new variety takes the normal physiological passage along broiler GIT similar to the conventional line. In addition, Bt 176 maize DNA appears to be partially degraded in different parts of GIT comparable to the DNA of the control maize line. Results of the metabolic fate of maize DNA in broiler blood, muscles and organs indicated that only short DNA fragments (199 bp) derived from the plant chloroplast gene could be detected in the blood, skeletal muscles, liver, spleen and kidney, which disappeared after prolongation the fasting time. In heart muscle, bursa of Fabricius and thymus, no plant chloroplast DNA was found. Bt gene specific constructs from Bt 176 maize were not detected in any investigated blood or tissue samples.

Animal Feed↗

PubMed2000

The metabolic use of energy from dietary fat in broilers is affected by fatty acid saturation.

1. Two experiments were performed to evaluate the effect of dietary fat on performance and fat and protein accretion in broiler chickens according to the degree of saturation. 2. The first experiment was designed to test 2 sources of dietary fat and 3 levels of dietary energy using a factorial (2x3) experimental design. The foods were formulated to maintain a constant ratio of energy to protein (and other nutrients). There were no significant differences in weight gain, intake, final body weight or food to gain ratio between broilers fed on diets differing solely in the degree of fat saturation. Broilers fed on diets containing animal fat showed higher whole-body fat retention (P=0.02) and lower protein accretion (P=0.03) than those fed on diets containing vegetable oils. 3. In the second experiment, only 1 concentration of fat (tallow, lard or sunflower oil) was incorporated into the experimental diets, providing different energy to protein ratios. The carcase protein content was not affected by dietary fat source, while total fat accretion (P=0.01) and energy retention (P=0.14) were highest in broilers fed on a diet containing tallow. 4. The findings suggest that the degree of saturation of dietary fats affects their metabolic use and fat accumulation in broiler chickens.

Animal Feed↗

PubMed2001

The effects of dietary L-carnitine supplementation on the performance, organ weights and circulating hormone and metabolite concentrations of broiler chickens reared under a normal or low temperature schedule.

1. The present study examined the effects of the addition of 100 mg/kg L-carnitine to the basal starter (containing 17.8 mg/kg L-carnitine) and finisher (containing 22.9 mg/kg L-carnitine) diets on performance, organ weights and plasma hormone and metabolite concentrations of male and female broiler chickens. The broiler chickens were reared either in a room with a normal temperature (NT) program or with a low temperature (LT) program (rapid decrease from 28 degrees C to 20 degrees C at 14 d of age). 2. Broiler chickens reared under the LT schedule consumed more food and attained a greater body weight at 42 d of age than their counterparts reared under NT schedule, without any difference in food efficiency or abdominal fat content. Dietary L-carnitine supplementation had no significant effects on any of these production parameters, except for a reduction in the abdominal fat content of female NT chickens. However, the LT schedule and dietary L-carnitine supplementation greatly increased absolute and proportional heart weights. The elevated heart weights were not due to right ventricle hypertrophy. 3. Both the LT program and L-carnitine supplementation increased circulating plasma triiodothyronine concentrations. There were also some transient effects of both experimental variables on plasma growth hormone, glucose and triglyceride concentrations. 4. L-carnitine did not improve broiler performance. However, this result does not mean that L-carnitine supplementation cannot have beneficial effects in other circumstances. In view of the elevated proportional heart weights, it can also be argued that L-carnitine is a potential agent for reducing the incidence of metabolic diseases in broiler chickens.

Adipose Tissue↗

PubMed2003

The effect of short-term fasting on performance traits and rectal temperature of broilers during the summer season.

1. The present study was conducted to determine if detrimental effects of high temperature on broiler performance could be overcome by short-term fasting and to examine the effect of food withdrawal on the responses of two commercial strains (S1 and S2). 2. An experimental design was used with three feeding groups and two strains. Birds in the control (C) group were fed ad libitum during the experimental period (0 to 6 weeks), while feed was withdrawn in the other groups between 10:00 and 16:00 h during weeks 5 and 6 (F1) or week 6 (F2), respectively. After standard brooding for the first 3 weeks temperature and humidity varied according to outside climate between 4 and 6 weeks of age. 3. Feeding strategy significantly affected body weight at week 6 (BW6) and daily weight gain during week 6 (DWG5-6). F2 gave the best results in BW6 and DWG5-6. Strain effect was significant on DWG4-5 and DWG5-6; S1 had higher DWG4-5 and S2 gained more at the last stage. S1C broilers had greater BW6 than S2C but the S2 strain gave a better response to short-term fasting compared with S1 and this resulted in significant strain by feeding interaction effect on BW6 and DWG5-6. 4. It was shown that short-term fasting was an effective method for controlling rectal temperature (RT) of broilers at 5 and 6 weeks of age. 5. Total food consumption (FCO-6), food conversion ratio (FCRO-6), mortality, and carcase characteristics were not affected by short-term fasting in the experimental conditions. 6. In conclusion, it can be recommended that broiler producers may practise 6 h of fasting during the hot period of the day without any adverse effect on slaughter weight and FCR when the birds are close to the average slaughter weight and a heat wave is expected. Strain differences in RT measurements also indicate the importance of choosing strains to be used in hot and warm climate conditions with attention to the thermoregulation ability of broilers.

Animal Feed↗

PubMed2005

Use of Trichosporon mycotoxinivorans to suppress the effects of ochratoxicosis on the immune system of broiler chicks.

(1) The objective of this study was to determine whether the dietary inclusion of Trichosporon mycotoxinivorans (TRM) could suppress the detrimental effects of ochratoxin A (OTA) on the immune system of broiler chicks. (2) Six experimental treatments were tested in 300 1-d-old broiler chicks. Treatments included addition to a standard broiler ration of neither OTA nor TRM (Diet 1), OTA alone (500 microg/kg), OTA plus TRM at three inclusion rates (10(4) CFU/g of feed, 10(5) CFU/g, 10(6) CFU/g) and TRM alone at 10(5) CFU/g of feed. The ration was fed to chicks for 42 d. (3) Blood samples were collected at d 10, 20, 30 and 40 and macrophages and heterophils were isolated. The following variables were determined in macrophages and heterophils activated by phorbol myristate acetate (65 microM): cell viability, total cell-associated urokinase-plasminogen activator (u-PA), membrane-bound u-PA, free u-PA binding sites and superoxide production. (4) There was a decrease in the viability of macrophages and heterophils from chicks receiving OTA-contaminated feed compared to the viability of cells from control birds at d 40. Dietary TRM completely blocked the effect of OTA on cell viability; all three inclusion rates were equally effective. There was a decrease in total cell-associated and membrane-bound u-PA in macrophages and heterophils of chicks receiving OTA-contaminated feed compared to the corresponding values in control birds for heterophils at d 30 and 40 and for the macrophages at d 40. (5) Similarly, dietary TRM abolished the effect of OTA on total cell-associated and membrane-bound u-PA activity. All three inclusion rates of yeast were equally effective. Heterophils, but not macrophages, isolated from chicks receiving OTA-contaminated diet produced less superoxide anion compared to all other diet groups at d 30 and 40. (6) The immune system is a primary target of OTA toxicity in broilers: several functional properties of macrophages and heterophils were depressed in chicks fed OTA-contaminated feed. There was a delay of 30d before the immunosuppressive effect became apparent. The dietary inclusion of TRM completely blocked the detrimental effects of OTA on several immune properties in broilers.

Animal Feed↗

PubMed2004

Dietary isoleucine responses in male broiler chickens.

1. Three experiments were conducted to measure growth and carcase responses of growing and finishing broilers fed on test diets formulated to be deficient in isoleucine (Ile). 2. Dose titration methodology was used to measure growth and carcase responses of growing and finishing broilers to graduations of Ile in three additional experiments. 3. The experiments were conducted from d 18 to 30, 30 to 42, and 42 to 56. 4. Broilers given Ile-deficient test diets had poorer weight gain, feed conversion and carcase responses than broilers fed on Ile test diets containing a surfeit of Ile. Adding supplemental Ile to the test diet resulted in equivalent growth and carcase responses to those of broilers fed on the control diet with equal Ile from intact protein sources. 5. Recommended total Ile needs varied between 6.7 and 7.1 g/kg from d 18 to 30, 6.4 to 6.6 g/kg from d 30 to 42, and 5.5 to 6.6 g/kg from d 42 to 56.

Animal Feed↗

PubMed2004

Differences in catecholamine metabolism and behaviour in neonatal broiler and layer chicks.

1. To clarify the difference in behavioural activities and catecholamine metabolism between layer and broiler-type chicks two experiments were conducted. 2. In experiment 1, 1-d-old male layer and broiler chicks were placed in an open-field area and their responses were investigated for 10 min. The responses of the two strains were remarkably different, with broilers being less active than layers. Vocalisations rapidly decreased in broilers whereas those of layers remained elevated during the 10 min. 3. In experiment 2, 1-d-old chicks of both strains were killed and brain catecholamine concentrations were determined in three parts of the brain: telencephalon, optic lobe and brain stem. 4. In the whole brain, dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) were significantly higher in broilers. However, the values for norepinephrine (NE), epinephrine (E) and 4-hydroxy-3-methoxyphenylacetic acid (HVA) were similar between strains. The ratios of metabolite/precursor were also calculated: HVA/DOPAC was higher in layers, while NE/DA, E/NE and DOPAC/DA were not significantly different between strains. 5. These results suggest that behavioural activities differ greatly, while there are some differences in catecholamine metabolism between the two strains.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2004

Breast blisters in groups of slow-growing broilers in relation to strain and the availability and use of perches.

1. The relationship between perching behaviour, availability of perches and the incidence and severity of breast blisters in broilers was investigated together with a comparison between two slow-growing broiler strains. 2. Sixteen single strain groups (n = 60) of Labresse and i657 broilers were subjected throughout the experiment to one of three perch availabilities: 15 cm per bird (Labresse and i657), 7.5 cm per bird (i657 only), and 0 cm per bird (i657 only) with 4 replicates per treatment. The birds were housed indoors from one day old, and at 43 d of age 52 birds from each group were moved to outdoor housing facilities with access to grass-covered outdoor areas until slaughter at 84 d of age. 3. The use of perches was monitored via video recordings throughout the experimental period. The severity of breast blisters was recorded on a scale from 0 to 2 at slaughter. 4. Groups of i657 with 15 cm perch per bird used these more than groups with 7.5 cm perch per bird (19% vs 8% of birds perching at midnight). A positive association between access to perches and severe breast blisters (score 2) was found in the groups of i657, with odds ratios of 3.1 and 3.4 for 7.5 and 15.0 cm per bird, respectively, relative to the no-perch treatment. 5. Labresse were more likely to develop breast blisters than i657 (odds ratio 3.5), but used the perches less (0.1 vs 9.5 birds perching at midnight) and weighed less (2011 g vs 2246 g) than i657. 6. Males had a higher incidence of breast blisters than females (odds ratio 12.2), and this was most prominent in the Labresse strain (odds ratio 40.0). 7. In some broiler strains access to perches may be associated with an increase in the occurrence of severe breast blisters, but strain and sex of broiler chickens appear to have a much larger influence than access to perches on the incidence of breast blisters.

Animals↗

PubMed2005

Dietary balanced protein in broiler chickens. 1. A flexible and practical tool to predict dose-response curves.

An empirical model of exponential form was developed, different versions of which can be used to predict growth rate, feed conversion and carcase and breast meat yield of broiler chickens as a function of dietary balanced protein (DBP) content. The model was developed to support decision-making by nutritionists. The model helps in determining DBP contents that maximise profit. The model avoids the practical disadvantages of existing methods. In contrast with mechanistic models, only data that are generally known by broiler nutritionists are required as input. Compared with predictions derived from one or a few feeding trials, the model predictions are more accurate (because the model was derived from many data-sets) and more flexible (because a description of the type of broiler was included as input for the model). Broiler response studies from the literature and the Nutreco Poultry and Rabbit Research Centre (27 data-sets in total) were used in the model development to select significant variables, to quantify the parameters and to evaluate the accuracy of the predictions. Input variables were DBP content, maximum performance level, age, year (indicating genetic potential) and sex. The model, including the assumption that the shape of the dose-response curves to DBP content is independent of broiler and feed characteristics, gave an accurate simulation of growth rate, feed conversion and breast meat for nearly all data-sets. Effects of DBP content on carcase yield were relatively small, except for carcases without skin and skin fat.

Animal Feed↗

PubMed2006

Thermoregulatory capacity and muscle membrane integrity are compromised in broilers compared with layers at the same age or body weight.

1. The effects of acute heat stress (2 h at 32 degrees C and 75% RH) on body temperature and indices of respiratory thermoregulation and skeletal muscle function were examined in two divergently selected male grandparent lines of broiler and layer-type chickens at two ages (35 and 63 d), or at a similar body weight (approximately 2.2 kg). 2. The two chicken lines exhibited markedly different baseline blood acid-base and skeletal muscle characteristics. At the same age or live weight, birds from the broiler line had significantly higher venous blood carbon dioxide tensions associated with lower blood pH. Plasma creatine kinase (CK) activities reflecting muscle membrane damage were also greatly elevated in the broiler line. 3. Exposure to acute heat stress caused an increase in deep body temperature, panting-induced acid-base disturbances and elevated plasma CK activity in both lines of chicken, an effect that increased with age. The extent of disturbances in acid-base regulation and heat-stress-induced myopathy were more pronounced in the broiler than the layer line at the same age or similar live weights. 4. It is suggested that genetic selection for high muscle growth in broiler lines has compromised their capacity to respond to an acute thermal challenge, leading to detrimental consequences for muscle function. This reduction in heat tolerance may have important implications for bird welfare and subsequent meat quality.

Aging↗

PubMed2006

Dietary cholecalciferol and phosphorus influence intestinal mucosa phytase activity in broiler chicks.

1. The role of cholecalciferol and phosphorus in the regulation of intestinal mucosa phytase was investigated in broiler chicks. 2. A total of 144 7-d-old male broiler chicks were grouped by weight into 6 blocks of 4 cages with 6 broiler chicks per cage. Four maize-soybean meal-based mash diets were randomly assigned to cages within each block. The 4 diets consisted of cholecalciferol at 0 or 75 microg/kg and total phosphorus at 3.6 or 7.0 g/kg in a 2 x 2 factorial arrangement. The birds were given the experimental diets for 12 d under conditions which excluded ultraviolet light. 3. Broiler chicks fed on diets with the higher concentration of cholecalciferol had higher Vmax and Km of the mucosa phytase, weight gain, feed intake, feed efficiency and percentage tibia ash, higher ileal digestibility of dry matter, energy, phosphorus (P) and calcium (Ca), and increased retention of dry matter, nitrogen, P, Ca and energy. 4. Broiler chicks receiving diets with the higher P concentration showed lower Vmax and Km of the intestinal mucosa phytase but greater weight gain, feed intake, feed efficiency and percentage tibia ash, higher ileal digestibility of dry matter, energy, P and nitrogen, and increased retention of dry matter, energy, nitrogen and Ca. 5. In conclusion, both dietary P and cholecalciferol influenced the activity of intestinal mucosa phytase.

6-Phytase↗

PubMed1987

Contribution of lipoprotein lipase to differences in fatness between broiler and layer-strain chickens.

The growth of abdominal fat in chickens from broiler and layer-strains up to 10 weeks of age was measured and compared with changes in plasma very low density lipoprotein (VLDL) concentration and tissue lipoprotein lipase activities. The growth of abdominal fat in broilers was much more rapid than in layer-strain chickens. Plasma VLDL concentrations in the two strains were similar up to 5 weeks of age but thereafter concentrations tended to be higher in broilers. Plasma VLDL concentrations in both strains were much lower than those necessary for maximum lipoprotein lipase activity. The lipoprotein lipase activity of abdominal fat increased much more rapidly in broilers than in layer-strain chickens. In both strains the pattern of its increase relative to body weight was similar to that of abdominal fat. Differences in the lipoprotein lipase activity of abdominal fat between strains were attributed to differences in both activity/adipocyte and number of adipocytes. They were reduced or abolished if activity was expressed relative to tissue weight, or to its content of DNA or protein. The results strongly suggest that the greater lipoprotein lipase activity of the abdominal fat pad in broilers is an important factor in its rapid growth.

Adipose Tissue↗

PubMed1990

Potential of chemical regulation of food intake and body weight of broiler breeder chicks.

1. Two experiments were performed to evaluate the potential of phenylpropanolamine hydrochloride and monensin sodium as appetite- and weight-control agents for Indian River broiler breeder chicks. 2. In experiment 1, a total of 300 day-old sexed broiler breeder chicks were individually weighed and placed in battery cages. They were randomly assigned to 5 dietary treatments, namely 0, 50, 100, 200 and 400 mg/kg of phenylpropanolamine hydrochloride added to a maize-soyabean meal basal diet. 3. In experiment 2, a total of 400 day-old sexed broiler breeder chicks were randomly assigned to 10 dietary treatments which were a combination of two concentrations of dietary crude protein (200 and 150 g/kg) and 5 different concentrations of added drugs in the diet, namely 0, 500 and 800 mg/kg of phenylpropanolamine hydrochloride and 200 and 300 mg/kg of monensin sodium. 4. Food consumption and body weight gain were significantly reduced by feeding diets containing the drugs but mortality was not significantly affected. Birds showed evidence of increased tolerance, with age, to phenylpropanolamine but not to monensin. 5. Monensin sodium, at high inclusion rates, was found to be a more potent and effective appetite- and growth-depressing agent for broiler breeder chicks than phenylpropanolamine and may have application in broiler breeder production using an ad libitum feeding programme.

Animal Feed↗